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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sat Nov 18 2023 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are unlikely through tonight. ...Synopsis... A substantial pattern change is underway in mid/upper levels, related to the progressive nature of high-amplitude synoptic troughing now found over eastern North America and just off the Pacific Coast. A strong shortwave trough -- apparent in moisture- channel imagery just offshore from Cape Mendocino -- will move slowly inland today and either dissipate or be absorbed by an even stronger and amplifying upstream perturbation, now located about 500-600 nm west of the WA/OR coastline. By 12Z tomorrow, this should result in a negatively tilted trough and prominent 500-mb vorticity banner from just west of Vancouver Island southeastward across central OR to near LAS. Preceding corridors of large-scale ascent (DCVA aloft and/or low-level warm advection), amidst modest low/middle-level moisture inland, will support a large, irregular area of isolated thunder potential over the West. A southern-stream belt of enhanced and difluent cyclonic flow -- containing a few low-amplitude shortwaves -- will spread southeast of the trough across AZ and NM, reaching the southern Plains by 12Z. In the low levels, offshore flow will continue across at least the eastern 1/2-2/3 of the Gulf through the period, following the cold- frontal passage related to the current Eastern mid/upper trough. While surface onshore flow will occur by the end of the period over the Texas Coast, short marine trajectories will allow little time for substantial modification. Still, enough moist advection will occur above the surface to support elevated thunderstorms developing eastward from NM across portions of the south-central Plains tonight. There, increasing (but still marginal) return moisture will be superimposed with coupled ascent from low-level warm advection and mid/upper lift, located leftward of the cyclonically curved jet max aloft. ..Inland northern CA... Isolated shallow, but perhaps at least briefly rotating, cells may occur this afternoon over the Sacramento Valley. Such activity would follow closely behind earlier precip/convection now progged to greatly limit diurnal destabilization (MLCAPE 200 J/kg or less in forecast soundings, with weak low-level lapse rates). Though any associated severe threat still appears strongly conditional, veering flow with height (as already evident in the 12Z OAK RAOB) and up to about 75-125 J/kg of 500-m SRH appear possible over the area into late afternoon. If greater destabilization potential becomes apparent, informed by 12Z and later guidance and mesoscale trends, marginal unconditional tornado probabilities may be needed in a succeeding outlook. ..Edwards/Leitman.. 11/18/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sat Nov 18 2023 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are unlikely through tonight. ...Synopsis... A substantial pattern change is underway in mid/upper levels, related to the progressive nature of high-amplitude synoptic troughing now found over eastern North America and just off the Pacific Coast. A strong shortwave trough -- apparent in moisture- channel imagery just offshore from Cape Mendocino -- will move slowly inland today and either dissipate or be absorbed by an even stronger and amplifying upstream perturbation, now located about 500-600 nm west of the WA/OR coastline. By 12Z tomorrow, this should result in a negatively tilted trough and prominent 500-mb vorticity banner from just west of Vancouver Island southeastward across central OR to near LAS. Preceding corridors of large-scale ascent (DCVA aloft and/or low-level warm advection), amidst modest low/middle-level moisture inland, will support a large, irregular area of isolated thunder potential over the West. A southern-stream belt of enhanced and difluent cyclonic flow -- containing a few low-amplitude shortwaves -- will spread southeast of the trough across AZ and NM, reaching the southern Plains by 12Z. In the low levels, offshore flow will continue across at least the eastern 1/2-2/3 of the Gulf through the period, following the cold- frontal passage related to the current Eastern mid/upper trough. While surface onshore flow will occur by the end of the period over the Texas Coast, short marine trajectories will allow little time for substantial modification. Still, enough moist advection will occur above the surface to support elevated thunderstorms developing eastward from NM across portions of the south-central Plains tonight. There, increasing (but still marginal) return moisture will be superimposed with coupled ascent from low-level warm advection and mid/upper lift, located leftward of the cyclonically curved jet max aloft. ..Inland northern CA... Isolated shallow, but perhaps at least briefly rotating, cells may occur this afternoon over the Sacramento Valley. Such activity would follow closely behind earlier precip/convection now progged to greatly limit diurnal destabilization (MLCAPE 200 J/kg or less in forecast soundings, with weak low-level lapse rates). Though any associated severe threat still appears strongly conditional, veering flow with height (as already evident in the 12Z OAK RAOB) and up to about 75-125 J/kg of 500-m SRH appear possible over the area into late afternoon. If greater destabilization potential becomes apparent, informed by 12Z and later guidance and mesoscale trends, marginal unconditional tornado probabilities may be needed in a succeeding outlook. ..Edwards/Leitman.. 11/18/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sat Nov 18 2023 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are unlikely through tonight. ...Synopsis... A substantial pattern change is underway in mid/upper levels, related to the progressive nature of high-amplitude synoptic troughing now found over eastern North America and just off the Pacific Coast. A strong shortwave trough -- apparent in moisture- channel imagery just offshore from Cape Mendocino -- will move slowly inland today and either dissipate or be absorbed by an even stronger and amplifying upstream perturbation, now located about 500-600 nm west of the WA/OR coastline. By 12Z tomorrow, this should result in a negatively tilted trough and prominent 500-mb vorticity banner from just west of Vancouver Island southeastward across central OR to near LAS. Preceding corridors of large-scale ascent (DCVA aloft and/or low-level warm advection), amidst modest low/middle-level moisture inland, will support a large, irregular area of isolated thunder potential over the West. A southern-stream belt of enhanced and difluent cyclonic flow -- containing a few low-amplitude shortwaves -- will spread southeast of the trough across AZ and NM, reaching the southern Plains by 12Z. In the low levels, offshore flow will continue across at least the eastern 1/2-2/3 of the Gulf through the period, following the cold- frontal passage related to the current Eastern mid/upper trough. While surface onshore flow will occur by the end of the period over the Texas Coast, short marine trajectories will allow little time for substantial modification. Still, enough moist advection will occur above the surface to support elevated thunderstorms developing eastward from NM across portions of the south-central Plains tonight. There, increasing (but still marginal) return moisture will be superimposed with coupled ascent from low-level warm advection and mid/upper lift, located leftward of the cyclonically curved jet max aloft. ..Inland northern CA... Isolated shallow, but perhaps at least briefly rotating, cells may occur this afternoon over the Sacramento Valley. Such activity would follow closely behind earlier precip/convection now progged to greatly limit diurnal destabilization (MLCAPE 200 J/kg or less in forecast soundings, with weak low-level lapse rates). Though any associated severe threat still appears strongly conditional, veering flow with height (as already evident in the 12Z OAK RAOB) and up to about 75-125 J/kg of 500-m SRH appear possible over the area into late afternoon. If greater destabilization potential becomes apparent, informed by 12Z and later guidance and mesoscale trends, marginal unconditional tornado probabilities may be needed in a succeeding outlook. ..Edwards/Leitman.. 11/18/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sat Nov 18 2023 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are unlikely through tonight. ...Synopsis... A substantial pattern change is underway in mid/upper levels, related to the progressive nature of high-amplitude synoptic troughing now found over eastern North America and just off the Pacific Coast. A strong shortwave trough -- apparent in moisture- channel imagery just offshore from Cape Mendocino -- will move slowly inland today and either dissipate or be absorbed by an even stronger and amplifying upstream perturbation, now located about 500-600 nm west of the WA/OR coastline. By 12Z tomorrow, this should result in a negatively tilted trough and prominent 500-mb vorticity banner from just west of Vancouver Island southeastward across central OR to near LAS. Preceding corridors of large-scale ascent (DCVA aloft and/or low-level warm advection), amidst modest low/middle-level moisture inland, will support a large, irregular area of isolated thunder potential over the West. A southern-stream belt of enhanced and difluent cyclonic flow -- containing a few low-amplitude shortwaves -- will spread southeast of the trough across AZ and NM, reaching the southern Plains by 12Z. In the low levels, offshore flow will continue across at least the eastern 1/2-2/3 of the Gulf through the period, following the cold- frontal passage related to the current Eastern mid/upper trough. While surface onshore flow will occur by the end of the period over the Texas Coast, short marine trajectories will allow little time for substantial modification. Still, enough moist advection will occur above the surface to support elevated thunderstorms developing eastward from NM across portions of the south-central Plains tonight. There, increasing (but still marginal) return moisture will be superimposed with coupled ascent from low-level warm advection and mid/upper lift, located leftward of the cyclonically curved jet max aloft. ..Inland northern CA... Isolated shallow, but perhaps at least briefly rotating, cells may occur this afternoon over the Sacramento Valley. Such activity would follow closely behind earlier precip/convection now progged to greatly limit diurnal destabilization (MLCAPE 200 J/kg or less in forecast soundings, with weak low-level lapse rates). Though any associated severe threat still appears strongly conditional, veering flow with height (as already evident in the 12Z OAK RAOB) and up to about 75-125 J/kg of 500-m SRH appear possible over the area into late afternoon. If greater destabilization potential becomes apparent, informed by 12Z and later guidance and mesoscale trends, marginal unconditional tornado probabilities may be needed in a succeeding outlook. ..Edwards/Leitman.. 11/18/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0653 AM CST Sat Nov 18 2023 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are unlikely through tonight. ...Synopsis... A substantial pattern change is underway in mid/upper levels, related to the progressive nature of high-amplitude synoptic troughing now found over eastern North America and just off the Pacific Coast. A strong shortwave trough -- apparent in moisture- channel imagery just offshore from Cape Mendocino -- will move slowly inland today and either dissipate or be absorbed by an even stronger and amplifying upstream perturbation, now located about 500-600 nm west of the WA/OR coastline. By 12Z tomorrow, this should result in a negatively tilted trough and prominent 500-mb vorticity banner from just west of Vancouver Island southeastward across central OR to near LAS. Preceding corridors of large-scale ascent (DCVA aloft and/or low-level warm advection), amidst modest low/middle-level moisture inland, will support a large, irregular area of isolated thunder potential over the West. A southern-stream belt of enhanced and difluent cyclonic flow -- containing a few low-amplitude shortwaves -- will spread southeast of the trough across AZ and NM, reaching the southern Plains by 12Z. In the low levels, offshore flow will continue across at least the eastern 1/2-2/3 of the Gulf through the period, following the cold- frontal passage related to the current Eastern mid/upper trough. While surface onshore flow will occur by the end of the period over the Texas Coast, short marine trajectories will allow little time for substantial modification. Still, enough moist advection will occur above the surface to support elevated thunderstorms developing eastward from NM across portions of the south-central Plains tonight. There, increasing (but still marginal) return moisture will be superimposed with coupled ascent from low-level warm advection and mid/upper lift, located leftward of the cyclonically curved jet max aloft. ..Inland northern CA... Isolated shallow, but perhaps at least briefly rotating, cells may occur this afternoon over the Sacramento Valley. Such activity would follow closely behind earlier precip/convection now progged to greatly limit diurnal destabilization (MLCAPE 200 J/kg or less in forecast soundings, with weak low-level lapse rates). Though any associated severe threat still appears strongly conditional, veering flow with height (as already evident in the 12Z OAK RAOB) and up to about 75-125 J/kg of 500-m SRH appear possible over the area into late afternoon. If greater destabilization potential becomes apparent, informed by 12Z and later guidance and mesoscale trends, marginal unconditional tornado probabilities may be needed in a succeeding outlook. ..Edwards/Leitman.. 11/18/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0323 AM CST Sat Nov 18 2023 Valid 211200Z - 261200Z ...DISCUSSION... ...D4/Tuesday - Parts of the Southeast/Carolinas... Considerable spread is present within extended-range guidance by D4/Tuesday with regard to the synoptic pattern. In general, the primary surface cyclone is expected move quickly northeastward from the lower/mid MS Valley toward the lower Great Lakes, as the trailing cold front moves through the Southeast. Modestly organized convection may persist along/ahead of the front through the day across parts of AL/GA, within a moist and favorably sheared environment. However, limited instability and weakening large-scale ascent in the wake of the departing cyclone may tend to the limit the coverage and magnitude of the severe threat. Tuesday night, prefrontal southerly flow will support low-level moisture return into parts of the Carolinas. This may be accompanied by increasingly favorable low-level and deep-layer shear, but most guidance suggests that instability will remain quite limited, and the potential for organized deep convection remains quite uncertain. ...D5/Wednesday and beyond... Predictability regarding the synoptic pattern becomes quite low by D5/Wednesday and beyond. The 18/00Z GFS is a notable outlier in depicting a vigorous mid/upper-level shortwave trough and surface cyclone moving through parts of the Carolinas and Mid Atlantic on Wednesday. While this scenario would potentially support some severe-thunderstorm potential, this solution has little support from other guidance at this time. Most guidance suggests limited severe-thunderstorm potential through the end of the week, in the wake of a cold-frontal intrusion into the Gulf of Mexico. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0323 AM CST Sat Nov 18 2023 Valid 211200Z - 261200Z ...DISCUSSION... ...D4/Tuesday - Parts of the Southeast/Carolinas... Considerable spread is present within extended-range guidance by D4/Tuesday with regard to the synoptic pattern. In general, the primary surface cyclone is expected move quickly northeastward from the lower/mid MS Valley toward the lower Great Lakes, as the trailing cold front moves through the Southeast. Modestly organized convection may persist along/ahead of the front through the day across parts of AL/GA, within a moist and favorably sheared environment. However, limited instability and weakening large-scale ascent in the wake of the departing cyclone may tend to the limit the coverage and magnitude of the severe threat. Tuesday night, prefrontal southerly flow will support low-level moisture return into parts of the Carolinas. This may be accompanied by increasingly favorable low-level and deep-layer shear, but most guidance suggests that instability will remain quite limited, and the potential for organized deep convection remains quite uncertain. ...D5/Wednesday and beyond... Predictability regarding the synoptic pattern becomes quite low by D5/Wednesday and beyond. The 18/00Z GFS is a notable outlier in depicting a vigorous mid/upper-level shortwave trough and surface cyclone moving through parts of the Carolinas and Mid Atlantic on Wednesday. While this scenario would potentially support some severe-thunderstorm potential, this solution has little support from other guidance at this time. Most guidance suggests limited severe-thunderstorm potential through the end of the week, in the wake of a cold-frontal intrusion into the Gulf of Mexico. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0323 AM CST Sat Nov 18 2023 Valid 211200Z - 261200Z ...DISCUSSION... ...D4/Tuesday - Parts of the Southeast/Carolinas... Considerable spread is present within extended-range guidance by D4/Tuesday with regard to the synoptic pattern. In general, the primary surface cyclone is expected move quickly northeastward from the lower/mid MS Valley toward the lower Great Lakes, as the trailing cold front moves through the Southeast. Modestly organized convection may persist along/ahead of the front through the day across parts of AL/GA, within a moist and favorably sheared environment. However, limited instability and weakening large-scale ascent in the wake of the departing cyclone may tend to the limit the coverage and magnitude of the severe threat. Tuesday night, prefrontal southerly flow will support low-level moisture return into parts of the Carolinas. This may be accompanied by increasingly favorable low-level and deep-layer shear, but most guidance suggests that instability will remain quite limited, and the potential for organized deep convection remains quite uncertain. ...D5/Wednesday and beyond... Predictability regarding the synoptic pattern becomes quite low by D5/Wednesday and beyond. The 18/00Z GFS is a notable outlier in depicting a vigorous mid/upper-level shortwave trough and surface cyclone moving through parts of the Carolinas and Mid Atlantic on Wednesday. While this scenario would potentially support some severe-thunderstorm potential, this solution has little support from other guidance at this time. Most guidance suggests limited severe-thunderstorm potential through the end of the week, in the wake of a cold-frontal intrusion into the Gulf of Mexico. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0323 AM CST Sat Nov 18 2023 Valid 211200Z - 261200Z ...DISCUSSION... ...D4/Tuesday - Parts of the Southeast/Carolinas... Considerable spread is present within extended-range guidance by D4/Tuesday with regard to the synoptic pattern. In general, the primary surface cyclone is expected move quickly northeastward from the lower/mid MS Valley toward the lower Great Lakes, as the trailing cold front moves through the Southeast. Modestly organized convection may persist along/ahead of the front through the day across parts of AL/GA, within a moist and favorably sheared environment. However, limited instability and weakening large-scale ascent in the wake of the departing cyclone may tend to the limit the coverage and magnitude of the severe threat. Tuesday night, prefrontal southerly flow will support low-level moisture return into parts of the Carolinas. This may be accompanied by increasingly favorable low-level and deep-layer shear, but most guidance suggests that instability will remain quite limited, and the potential for organized deep convection remains quite uncertain. ...D5/Wednesday and beyond... Predictability regarding the synoptic pattern becomes quite low by D5/Wednesday and beyond. The 18/00Z GFS is a notable outlier in depicting a vigorous mid/upper-level shortwave trough and surface cyclone moving through parts of the Carolinas and Mid Atlantic on Wednesday. While this scenario would potentially support some severe-thunderstorm potential, this solution has little support from other guidance at this time. Most guidance suggests limited severe-thunderstorm potential through the end of the week, in the wake of a cold-frontal intrusion into the Gulf of Mexico. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0323 AM CST Sat Nov 18 2023 Valid 211200Z - 261200Z ...DISCUSSION... ...D4/Tuesday - Parts of the Southeast/Carolinas... Considerable spread is present within extended-range guidance by D4/Tuesday with regard to the synoptic pattern. In general, the primary surface cyclone is expected move quickly northeastward from the lower/mid MS Valley toward the lower Great Lakes, as the trailing cold front moves through the Southeast. Modestly organized convection may persist along/ahead of the front through the day across parts of AL/GA, within a moist and favorably sheared environment. However, limited instability and weakening large-scale ascent in the wake of the departing cyclone may tend to the limit the coverage and magnitude of the severe threat. Tuesday night, prefrontal southerly flow will support low-level moisture return into parts of the Carolinas. This may be accompanied by increasingly favorable low-level and deep-layer shear, but most guidance suggests that instability will remain quite limited, and the potential for organized deep convection remains quite uncertain. ...D5/Wednesday and beyond... Predictability regarding the synoptic pattern becomes quite low by D5/Wednesday and beyond. The 18/00Z GFS is a notable outlier in depicting a vigorous mid/upper-level shortwave trough and surface cyclone moving through parts of the Carolinas and Mid Atlantic on Wednesday. While this scenario would potentially support some severe-thunderstorm potential, this solution has little support from other guidance at this time. Most guidance suggests limited severe-thunderstorm potential through the end of the week, in the wake of a cold-frontal intrusion into the Gulf of Mexico. Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CST Sat Nov 18 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TEXAS INTO PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST... ...SUMMARY... Severe thunderstorms will be possible Monday afternoon into Monday night from east Texas into parts of the lower Mississippi Valley and Southeast. Damaging wind and a few tornadoes are expected to be the primary hazards, though isolated hail will also be possible. ...Synopsis... A complex mid/upper-level trough is forecast to gradually shift eastward across the central CONUS on Monday. A vigorous shortwave is expected to move through the base of the trough, potentially resulting in consolidation of a mid/upper-level cyclone from eastern portions of the central Plains toward the mid-MS Valley. As this occurs, a surface cyclone initially over the southern Plains is forecast to move eastward toward the lower MS Valley. A trailing cold front will move from east TX toward the ArkLaMiss region by early Tuesday morning. ...East TX into the lower MS Valley and Southeast... Increasingly rich low-level moisture (with dewpoints into the mid/upper 60s F) is expected to advance northward during the day on Monday from east TX into the lower MS Valley, in advance of the surface low and cold front. Modest heating will support moderate buoyancy along/east of the front across east TX, where storm development is possible by late afternoon. Strengthening deep-layer shear will support supercell potential, though there may be a tendency toward more of a cluster or linear mode as storm coverage increases along/ahead of the front into the evening. Initial storm development from east TX toward the ArkLaTex will pose a threat of large hail and locally damaging gusts. With time, the hail threat may tend to decrease, but the tornado threat will increase with any persistent supercells and/or line-embedded mesovortices as low-level shear/SRH strengthens during the evening. Instability will tend to weaken with eastward extent, but any organized storm structures may continue to pose a threat of locally damaging wind and a tornado or two into the overnight, as they move through a moist and strongly sheared environment. While guidance has come into somewhat better agreement regarding the scenario described above, important differences remain with respect to the amplitude and intensity of the basal shortwave trough and attendant surface cyclone. The stronger solutions would support greater low-level mass response, and a greater tornado/wind threat compared to the weaker and less amplified solutions. A rather broad Slight Risk has been maintained with this outlook, in order to account for various plausible scenarios regarding the magnitude and favored corridor of the primary severe risk. ..Dean.. 11/18/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CST Sat Nov 18 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TEXAS INTO PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST... ...SUMMARY... Severe thunderstorms will be possible Monday afternoon into Monday night from east Texas into parts of the lower Mississippi Valley and Southeast. Damaging wind and a few tornadoes are expected to be the primary hazards, though isolated hail will also be possible. ...Synopsis... A complex mid/upper-level trough is forecast to gradually shift eastward across the central CONUS on Monday. A vigorous shortwave is expected to move through the base of the trough, potentially resulting in consolidation of a mid/upper-level cyclone from eastern portions of the central Plains toward the mid-MS Valley. As this occurs, a surface cyclone initially over the southern Plains is forecast to move eastward toward the lower MS Valley. A trailing cold front will move from east TX toward the ArkLaMiss region by early Tuesday morning. ...East TX into the lower MS Valley and Southeast... Increasingly rich low-level moisture (with dewpoints into the mid/upper 60s F) is expected to advance northward during the day on Monday from east TX into the lower MS Valley, in advance of the surface low and cold front. Modest heating will support moderate buoyancy along/east of the front across east TX, where storm development is possible by late afternoon. Strengthening deep-layer shear will support supercell potential, though there may be a tendency toward more of a cluster or linear mode as storm coverage increases along/ahead of the front into the evening. Initial storm development from east TX toward the ArkLaTex will pose a threat of large hail and locally damaging gusts. With time, the hail threat may tend to decrease, but the tornado threat will increase with any persistent supercells and/or line-embedded mesovortices as low-level shear/SRH strengthens during the evening. Instability will tend to weaken with eastward extent, but any organized storm structures may continue to pose a threat of locally damaging wind and a tornado or two into the overnight, as they move through a moist and strongly sheared environment. While guidance has come into somewhat better agreement regarding the scenario described above, important differences remain with respect to the amplitude and intensity of the basal shortwave trough and attendant surface cyclone. The stronger solutions would support greater low-level mass response, and a greater tornado/wind threat compared to the weaker and less amplified solutions. A rather broad Slight Risk has been maintained with this outlook, in order to account for various plausible scenarios regarding the magnitude and favored corridor of the primary severe risk. ..Dean.. 11/18/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CST Sat Nov 18 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TEXAS INTO PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST... ...SUMMARY... Severe thunderstorms will be possible Monday afternoon into Monday night from east Texas into parts of the lower Mississippi Valley and Southeast. Damaging wind and a few tornadoes are expected to be the primary hazards, though isolated hail will also be possible. ...Synopsis... A complex mid/upper-level trough is forecast to gradually shift eastward across the central CONUS on Monday. A vigorous shortwave is expected to move through the base of the trough, potentially resulting in consolidation of a mid/upper-level cyclone from eastern portions of the central Plains toward the mid-MS Valley. As this occurs, a surface cyclone initially over the southern Plains is forecast to move eastward toward the lower MS Valley. A trailing cold front will move from east TX toward the ArkLaMiss region by early Tuesday morning. ...East TX into the lower MS Valley and Southeast... Increasingly rich low-level moisture (with dewpoints into the mid/upper 60s F) is expected to advance northward during the day on Monday from east TX into the lower MS Valley, in advance of the surface low and cold front. Modest heating will support moderate buoyancy along/east of the front across east TX, where storm development is possible by late afternoon. Strengthening deep-layer shear will support supercell potential, though there may be a tendency toward more of a cluster or linear mode as storm coverage increases along/ahead of the front into the evening. Initial storm development from east TX toward the ArkLaTex will pose a threat of large hail and locally damaging gusts. With time, the hail threat may tend to decrease, but the tornado threat will increase with any persistent supercells and/or line-embedded mesovortices as low-level shear/SRH strengthens during the evening. Instability will tend to weaken with eastward extent, but any organized storm structures may continue to pose a threat of locally damaging wind and a tornado or two into the overnight, as they move through a moist and strongly sheared environment. While guidance has come into somewhat better agreement regarding the scenario described above, important differences remain with respect to the amplitude and intensity of the basal shortwave trough and attendant surface cyclone. The stronger solutions would support greater low-level mass response, and a greater tornado/wind threat compared to the weaker and less amplified solutions. A rather broad Slight Risk has been maintained with this outlook, in order to account for various plausible scenarios regarding the magnitude and favored corridor of the primary severe risk. ..Dean.. 11/18/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CST Sat Nov 18 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TEXAS INTO PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST... ...SUMMARY... Severe thunderstorms will be possible Monday afternoon into Monday night from east Texas into parts of the lower Mississippi Valley and Southeast. Damaging wind and a few tornadoes are expected to be the primary hazards, though isolated hail will also be possible. ...Synopsis... A complex mid/upper-level trough is forecast to gradually shift eastward across the central CONUS on Monday. A vigorous shortwave is expected to move through the base of the trough, potentially resulting in consolidation of a mid/upper-level cyclone from eastern portions of the central Plains toward the mid-MS Valley. As this occurs, a surface cyclone initially over the southern Plains is forecast to move eastward toward the lower MS Valley. A trailing cold front will move from east TX toward the ArkLaMiss region by early Tuesday morning. ...East TX into the lower MS Valley and Southeast... Increasingly rich low-level moisture (with dewpoints into the mid/upper 60s F) is expected to advance northward during the day on Monday from east TX into the lower MS Valley, in advance of the surface low and cold front. Modest heating will support moderate buoyancy along/east of the front across east TX, where storm development is possible by late afternoon. Strengthening deep-layer shear will support supercell potential, though there may be a tendency toward more of a cluster or linear mode as storm coverage increases along/ahead of the front into the evening. Initial storm development from east TX toward the ArkLaTex will pose a threat of large hail and locally damaging gusts. With time, the hail threat may tend to decrease, but the tornado threat will increase with any persistent supercells and/or line-embedded mesovortices as low-level shear/SRH strengthens during the evening. Instability will tend to weaken with eastward extent, but any organized storm structures may continue to pose a threat of locally damaging wind and a tornado or two into the overnight, as they move through a moist and strongly sheared environment. While guidance has come into somewhat better agreement regarding the scenario described above, important differences remain with respect to the amplitude and intensity of the basal shortwave trough and attendant surface cyclone. The stronger solutions would support greater low-level mass response, and a greater tornado/wind threat compared to the weaker and less amplified solutions. A rather broad Slight Risk has been maintained with this outlook, in order to account for various plausible scenarios regarding the magnitude and favored corridor of the primary severe risk. ..Dean.. 11/18/2023 Read more

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CST Sat Nov 18 2023 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TEXAS INTO PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST... ...SUMMARY... Severe thunderstorms will be possible Monday afternoon into Monday night from east Texas into parts of the lower Mississippi Valley and Southeast. Damaging wind and a few tornadoes are expected to be the primary hazards, though isolated hail will also be possible. ...Synopsis... A complex mid/upper-level trough is forecast to gradually shift eastward across the central CONUS on Monday. A vigorous shortwave is expected to move through the base of the trough, potentially resulting in consolidation of a mid/upper-level cyclone from eastern portions of the central Plains toward the mid-MS Valley. As this occurs, a surface cyclone initially over the southern Plains is forecast to move eastward toward the lower MS Valley. A trailing cold front will move from east TX toward the ArkLaMiss region by early Tuesday morning. ...East TX into the lower MS Valley and Southeast... Increasingly rich low-level moisture (with dewpoints into the mid/upper 60s F) is expected to advance northward during the day on Monday from east TX into the lower MS Valley, in advance of the surface low and cold front. Modest heating will support moderate buoyancy along/east of the front across east TX, where storm development is possible by late afternoon. Strengthening deep-layer shear will support supercell potential, though there may be a tendency toward more of a cluster or linear mode as storm coverage increases along/ahead of the front into the evening. Initial storm development from east TX toward the ArkLaTex will pose a threat of large hail and locally damaging gusts. With time, the hail threat may tend to decrease, but the tornado threat will increase with any persistent supercells and/or line-embedded mesovortices as low-level shear/SRH strengthens during the evening. Instability will tend to weaken with eastward extent, but any organized storm structures may continue to pose a threat of locally damaging wind and a tornado or two into the overnight, as they move through a moist and strongly sheared environment. While guidance has come into somewhat better agreement regarding the scenario described above, important differences remain with respect to the amplitude and intensity of the basal shortwave trough and attendant surface cyclone. The stronger solutions would support greater low-level mass response, and a greater tornado/wind threat compared to the weaker and less amplified solutions. A rather broad Slight Risk has been maintained with this outlook, in order to account for various plausible scenarios regarding the magnitude and favored corridor of the primary severe risk. ..Dean.. 11/18/2023 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CST Sat Nov 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level flow pattern is expected to persist D2/Sunday as an upper trough over the East Coast continues to move offshore. A broad western US trough is expected to amplify through the weekend before ejecting eastward into the central US by the end of the forecast period. Transient surface high pressure will persist over the eastern third of the country in the wake of an earlier cold front. Cooler and drier conditions are possible over parts of the central and southern Appalachians. Occasional gusty winds near the higher terrain may support brief elevated fire-weather conditions within areas of dry fuels across NC and VA. Localized dry and breezy conditions are also possible over parts of eastern NM. However, with only transient overlap of dry and breezy conditions, widespread fire-weather concerns appear low for much of the CONUS. ..Lyons.. 11/18/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CST Sat Nov 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level flow pattern is expected to persist D2/Sunday as an upper trough over the East Coast continues to move offshore. A broad western US trough is expected to amplify through the weekend before ejecting eastward into the central US by the end of the forecast period. Transient surface high pressure will persist over the eastern third of the country in the wake of an earlier cold front. Cooler and drier conditions are possible over parts of the central and southern Appalachians. Occasional gusty winds near the higher terrain may support brief elevated fire-weather conditions within areas of dry fuels across NC and VA. Localized dry and breezy conditions are also possible over parts of eastern NM. However, with only transient overlap of dry and breezy conditions, widespread fire-weather concerns appear low for much of the CONUS. ..Lyons.. 11/18/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CST Sat Nov 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level flow pattern is expected to persist D2/Sunday as an upper trough over the East Coast continues to move offshore. A broad western US trough is expected to amplify through the weekend before ejecting eastward into the central US by the end of the forecast period. Transient surface high pressure will persist over the eastern third of the country in the wake of an earlier cold front. Cooler and drier conditions are possible over parts of the central and southern Appalachians. Occasional gusty winds near the higher terrain may support brief elevated fire-weather conditions within areas of dry fuels across NC and VA. Localized dry and breezy conditions are also possible over parts of eastern NM. However, with only transient overlap of dry and breezy conditions, widespread fire-weather concerns appear low for much of the CONUS. ..Lyons.. 11/18/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CST Sat Nov 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level flow pattern is expected to persist D2/Sunday as an upper trough over the East Coast continues to move offshore. A broad western US trough is expected to amplify through the weekend before ejecting eastward into the central US by the end of the forecast period. Transient surface high pressure will persist over the eastern third of the country in the wake of an earlier cold front. Cooler and drier conditions are possible over parts of the central and southern Appalachians. Occasional gusty winds near the higher terrain may support brief elevated fire-weather conditions within areas of dry fuels across NC and VA. Localized dry and breezy conditions are also possible over parts of eastern NM. However, with only transient overlap of dry and breezy conditions, widespread fire-weather concerns appear low for much of the CONUS. ..Lyons.. 11/18/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0159 AM CST Sat Nov 18 2023 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... A progressive mid-level flow pattern is expected to persist D2/Sunday as an upper trough over the East Coast continues to move offshore. A broad western US trough is expected to amplify through the weekend before ejecting eastward into the central US by the end of the forecast period. Transient surface high pressure will persist over the eastern third of the country in the wake of an earlier cold front. Cooler and drier conditions are possible over parts of the central and southern Appalachians. Occasional gusty winds near the higher terrain may support brief elevated fire-weather conditions within areas of dry fuels across NC and VA. Localized dry and breezy conditions are also possible over parts of eastern NM. However, with only transient overlap of dry and breezy conditions, widespread fire-weather concerns appear low for much of the CONUS. ..Lyons.. 11/18/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more