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SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Tue May 20 2025 Valid 201200Z - 211200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN THE MID/DEEP SOUTH TO TN VALLEY AND CUMBERLAND PLATEAU... ...SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ...Synopsis... Multiple shortwave impulses and attendant mid-level jetlets will rotate through the southern to eastern portion of the broad mid/upper trough over the central states. A belt of 60-75 kt 500-mb southwesterlies should be centered on the Ark-La-Tex to Lower OH Valley by late afternoon. This should weaken thereafter, as the next shortwave impulse strengthens flow across the central Great Plains by evening. Primary surface cyclone should initially drift east from the IA/MO border into IL through the day, before accelerating eastward across IN/OH tonight. ...Mid/Deep South to the TN/Lower OH Valleys and Cumberland Plateau... An extensive swath of convection, currently from the Mid-MS Valley to the Red River, will likely be ongoing across parts of KY to the Ark-La-Miss at 12Z. The northern portion of this convective swath is consistently progged to persist into the diurnal heating cycle, aided by low-level warm theta-e advection along with mid-level height falls, and downstream destabilization. The latter is a primary source of uncertainty given the outpacing of convection thus far relative to 00Z CAM guidance. It does appear that there should be at least modest surface-based buoyancy being maintained downstream to warrant potential for a severe-producing QLCS into the afternoon. All severe threats are possible, but damaging winds may be the predominant coverage hazard. Tornado potential should peak where the QLCS approaches the surface warm front, before an abrupt drop-off in surface-based instability to its northeast. Greater boundary-layer destabilization is expected to the west-southwest of the early-day activity with relatively rapid airmass recovery amid low 70s surface dew points. Mid-level lapse rates will initially be steep over the Mid-MS Valley, but be more muted with southern extent into the Lower MS Valley. Still, moderate to large buoyancy with MLCAPE of 2000-3000 J/kg and minimal MLCIN should be common by mid-late afternoon. During that time frame, scattered supercells will likely develop along and just ahead of the eastward-moving cold front from the Lower OH Valley to the Ark-La-Miss. The modest mid-level lapse rates will be a limiting factor, but isolated significant severe hail (up to around tennis ball-size) will be possible in the initial supercell corridor. A broad swath of 30-40 kt low-level southwesterlies should be sufficient for at least a few strong tornadoes as supercells mature, most likely from western/southern KY across TN into northern portions of MS/AL. Guidance is insistent on upscale growth by early evening though, which would yield small-scale bows and potentially multiple damaging wind swaths. Embedded supercells should still persist well into the evening as storms spread east-southeast in the Southeast and southern Appalachians. But the aforementioned relative decrease in mid-level winds and muted lapse rates lower confidence on significant severe wind and greater tornado probability highlights. ...IL/IN... Within the left-exit region of the aforementioned mid-level jetlet, a dry slot and attendant corridor of steep lapse rates will likely evolve across portions of MO to IL/IN from midday into the afternoon. To the north of this, a cluster of sustained storm development is initially anticipated towards mid-afternoon, centered on central IL ahead of the surface low. Additional storms should develop farther south in time towards the Lower OH Valley. A mix of supercells and multicell clustering is anticipated, with isolated to scattered coverage of severe and all hazards possible. ..Grams/Weinman.. 05/20/2025 Read more

977
ABPZ20 KNHC 200502
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Mon May 19 2025

For the eastern North Pacific...east of 140 degrees west longitude:

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Reinhart

000
ABPZ20 KNHC 200502
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Mon May 19 2025

For the eastern North Pacific...east of 140 degrees west longitude:

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Reinhart

MD 0895 CONCERNING TORNADO WATCH 297...298... FOR EASTERN MISSOURI...CENTRAL AND NORTHERN ARKANSAS...WESTERN ILLINOIS
Mesoscale Discussion 0895 NWS Storm Prediction Center Norman OK 1042 PM CDT Mon May 19 2025 Areas affected...Eastern Missouri...Central and Northern Arkansas...Western Illinois Concerning...Tornado Watch 297...298... Valid 200342Z - 200545Z The severe weather threat for Tornado Watch 297, 298 continues. SUMMARY...A severe threat will likely continue across parts of central and northern Arkansas into parts of eastern Missouri and southwest Illinois. A severe threat may develop over parts of eastern Arkansas. Weather watch issuance may be needed to the east of WW 297. DISCUSSION...The latest mosaic radar imagery shows a line of strong to severe storms, located from central and northern Arkansas northward into southeast Missouri. Other severe storms are located in the vicinity of St Louis. Ahead of the line, moderate instability is analyzed by the RAP, with MLCAPE estimated in the 1500 to 2000 J/kg range. In addition, the RAP has a 40 to 50 knot low-level jet located across eastern and central Arkansas, with the nose of the jet in southeast Missouri. This is creating strong low-level shear, which is sampled by the Little Rock WSR-88D VWP, which has 0-3 km storm-relative helicity near 400 m2/s2. This suggests that a tornado threat will continue late this evening, with the threat maximized with rotating cells embedded in or ahead of the line. The potential for wind damage will be concentrated along the more intense parts of the line. The severe threat will increase as the line moves eastward into eastern Arkansas, where watch issuance may be needed. ..Broyles/Gleason.. 05/20/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...MEG...LSX...LZK...SGF... LAT...LON 34419338 34309273 34359183 34589111 35229043 36138977 37748917 38648909 39198953 39299038 39179094 39019118 38809137 38379149 37929170 37169193 36589223 35759294 35069376 34699380 34419338 MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN Read more