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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Thu May 23 2024 Valid 231300Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across a broad swath of the Great Plains this afternoon into tonight, with a few tornadoes and isolated very large hail. A concentration of severe winds -- some 75 mph or more -- is expected across a portion of the central Plains this evening into tonight. ...Synopsis... In mid/upper levels, a progressive flow belt will cover much of the CONUS, to the southeast through southwest of a persistent, somewhat flattened, quasistationary cyclone over the Canadian Prairie Provinces. This cyclone is loosely attached to another that is located over northern ON, and forecast to devolve into an open-wave trough as it moves into western/southern QC by 12Z tomorrow. The southern part of a preceding vorticity lobe will brush the St. Lawrence Valley and northern New England through 00Z. Meanwhile, another mid/upper low -- now over the northern Rockies -- should become part of a strong, open-wave trough by 00Z from eastern MT to eastern UT. This trough should pivot eastward to the Dakotas and NE by 12Z. To its south, a series of low-amplitude perturbations and vorticity lobes (some convectively generated/ enhanced) occupied the extensive west-southwest flow field from the Desert Southwest to the Appalachians. One of these -- now over southern OK and north TX -- is influencing ongoing convection from southeastern OK across AR -- and will move across the Mid-South and Tennessee Valley regions into tonight. Behind it, similar perturbations are apparent in moisture-channel imagery over Chihuahua, and over southeastern AZ/southwestern NM. These should reach central and northwest TX by 00Z. At the surface, 11Z analysis showed a low over east-central/ southeastern WY near TOR, with synoptic warm front over northern SD and southern MN. As the shortwave trough approaches, the low should deepen sharply and move to near PIR by 00Z, with cold front over western NE and northeastern CO. By 12Z, the low should reach eastern ND, with the cold front to northwestern IA, southeastern NE, south-central KS, and the TX South Plains. A warm to quasistationary front was drawn across the Red River region of TX/ OK, to the lower/middle Ohio Valley, becoming a cold front over parts of PA/upstate NY. This boundary will move eastward through the northern Appalachians, New England and much of the Mid-Atlantic through the period, while diffusely shifting northward amid areas of convection over the Mid-South and southern Plains. A dryline -- initially analyzed from the Big Bend region of TX across extreme eastern NM -- will develop northward over western parts of KS/NE today while the airmass to the east moistens. This boundary also will shift eastward into the eastern TX Panhandle near the OK border, as well as northwest/west-central TX through the afternoon. ...Central/northern Plains... Scattered thunderstorms are expected this afternoon and evening along parts of the warm and cold front near the surface low, with supercells possible in the first 2-3 hours. Damaging gusts, large to very large hail and a few tornadoes are possible. With relatively strong deep-layer and frontal forcing superimposed ahead of the progressive Rockies shortwave trough, an organized band of strong-severe thunderstorms should evolve along/ahead of the cold front and move southeastward across parts of the Dakotas and NE, eventually backbuilding into northern KS tonight as the cold front overtakes the dryline. This will cause the severe threat to transition more toward wind, with a swath of significant wind (65+ kt) potentially accompanying the QLCS. A few tornadoes also are possible with embedded mesocirculations near its edge. Though not optimally moist for the time of year, a corridor of 50s to low 60s surface dewpoints should become common this afternoon between the warm and cold fronts, combining with diurnal heating and steep midlevel lapse rates to support 1500-3000 J/kg MLCAPE. 45-55 kt effective-shear magnitudes should be common, with larger values possible near the warm front and low (but also, weaker instability). This will support both early supercells and persistence of the upscale MCS into parts of the central Plains and lower Missouri Valley regions. The southern end of well-organized, severe-wind potential over KS may be limited by residual outflow air advecting into the area from the south, while the eastern/northern ends are more uncertain. Although no change was made to the area of greatest wind probabilities this cycle, some reshaping of the "enhanced" area may be needed through the day as informed by 12Z and later guidance, as well as mesoscale analytic trends. However, with longer persistence of the MCS possible across IA/MO tonight, parts of the "slight" and "marginal" equivalent probabilities have been expanded eastward. ...Southern Plains... The width of the convectively undisturbed warm sector ahead of the southern Plains dryline is still uncertain, as considerable variability exists in progs for upscale growth of convection now manifest as a small but growing cluster over the Edwards Plateau/Hill Country/Concho Valley regions. This activity may produce sporadic large hail and damaging wind as well, through the remainder of the morning, as it proceeds across portions of central TX, with wind potential conditionally increasing where aggregation of cold pools can drive strongest forward propagation. Outflow and related theta-e deficits from any resulting complex will be advected northward into north TX and OK, with ambient theta-e decreasing northward into KS. Still, a corridor of favorable moisture should advect around the west (back) side of any such cold pool today and support isolated to widely scattered dryline development from northwest TX into parts of western OK/KS. Any sustained convection arising from that process may become supercellular, with all severe modes possible, and very large/ damaging hail a strong possibility. The least-modified air by earlier activity will have surface dewpoints in the upper 60s to low 70s F beneath EML-related steep lapse rates, fostering 3000-4000 J/kg MLCAPE. Long low-level hodographs will favor splitting storms, especially in the first couple hours after initiation, with some LLJ-aided enlargement possible in the 00-03Z time frame before parcels begin to stabilize unfavorably near the surface. ...Mid-South to Mid-Atlantic and New England... Isolated to scattered thunderstorms -- sometimes in small bands or clusters -- will persist through this afternoon along/ahead of the front from the Northeast to the lower Mississippi Valley. Areas of relative concentration within this belt will depend strongly on mesoscale boundary interactions ahead of the front (outflow and differential heating, as well as a prefrontal surface trough in the Northeast). Midlevel lapse rates, intensity of diurnal heating, and boundary-layer moisture each should generally decrease with northeastward extent. This should contribute to peak/preconvective MLCAPE in the 2000-3000 J/kg range around the lower/middle Mississippi and lower Ohio Valleys to 500-1500 J/kg over parts of the Mid-Atlantic and Northeast. Somewhat favorable deep shear amidst nearly unidirectional wind profiles will support potential for occasional damaging to isolated severe gusts throughout the Atlantic Coast States part of the corridor. A patchy distribution of marginal severe (hail and wind), with some mesobeta-scale concentrations possible, is expected across the remainder of the "marginal risk" swath. ..Edwards/Goss.. 05/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Thu May 23 2024 Valid 231300Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across a broad swath of the Great Plains this afternoon into tonight, with a few tornadoes and isolated very large hail. A concentration of severe winds -- some 75 mph or more -- is expected across a portion of the central Plains this evening into tonight. ...Synopsis... In mid/upper levels, a progressive flow belt will cover much of the CONUS, to the southeast through southwest of a persistent, somewhat flattened, quasistationary cyclone over the Canadian Prairie Provinces. This cyclone is loosely attached to another that is located over northern ON, and forecast to devolve into an open-wave trough as it moves into western/southern QC by 12Z tomorrow. The southern part of a preceding vorticity lobe will brush the St. Lawrence Valley and northern New England through 00Z. Meanwhile, another mid/upper low -- now over the northern Rockies -- should become part of a strong, open-wave trough by 00Z from eastern MT to eastern UT. This trough should pivot eastward to the Dakotas and NE by 12Z. To its south, a series of low-amplitude perturbations and vorticity lobes (some convectively generated/ enhanced) occupied the extensive west-southwest flow field from the Desert Southwest to the Appalachians. One of these -- now over southern OK and north TX -- is influencing ongoing convection from southeastern OK across AR -- and will move across the Mid-South and Tennessee Valley regions into tonight. Behind it, similar perturbations are apparent in moisture-channel imagery over Chihuahua, and over southeastern AZ/southwestern NM. These should reach central and northwest TX by 00Z. At the surface, 11Z analysis showed a low over east-central/ southeastern WY near TOR, with synoptic warm front over northern SD and southern MN. As the shortwave trough approaches, the low should deepen sharply and move to near PIR by 00Z, with cold front over western NE and northeastern CO. By 12Z, the low should reach eastern ND, with the cold front to northwestern IA, southeastern NE, south-central KS, and the TX South Plains. A warm to quasistationary front was drawn across the Red River region of TX/ OK, to the lower/middle Ohio Valley, becoming a cold front over parts of PA/upstate NY. This boundary will move eastward through the northern Appalachians, New England and much of the Mid-Atlantic through the period, while diffusely shifting northward amid areas of convection over the Mid-South and southern Plains. A dryline -- initially analyzed from the Big Bend region of TX across extreme eastern NM -- will develop northward over western parts of KS/NE today while the airmass to the east moistens. This boundary also will shift eastward into the eastern TX Panhandle near the OK border, as well as northwest/west-central TX through the afternoon. ...Central/northern Plains... Scattered thunderstorms are expected this afternoon and evening along parts of the warm and cold front near the surface low, with supercells possible in the first 2-3 hours. Damaging gusts, large to very large hail and a few tornadoes are possible. With relatively strong deep-layer and frontal forcing superimposed ahead of the progressive Rockies shortwave trough, an organized band of strong-severe thunderstorms should evolve along/ahead of the cold front and move southeastward across parts of the Dakotas and NE, eventually backbuilding into northern KS tonight as the cold front overtakes the dryline. This will cause the severe threat to transition more toward wind, with a swath of significant wind (65+ kt) potentially accompanying the QLCS. A few tornadoes also are possible with embedded mesocirculations near its edge. Though not optimally moist for the time of year, a corridor of 50s to low 60s surface dewpoints should become common this afternoon between the warm and cold fronts, combining with diurnal heating and steep midlevel lapse rates to support 1500-3000 J/kg MLCAPE. 45-55 kt effective-shear magnitudes should be common, with larger values possible near the warm front and low (but also, weaker instability). This will support both early supercells and persistence of the upscale MCS into parts of the central Plains and lower Missouri Valley regions. The southern end of well-organized, severe-wind potential over KS may be limited by residual outflow air advecting into the area from the south, while the eastern/northern ends are more uncertain. Although no change was made to the area of greatest wind probabilities this cycle, some reshaping of the "enhanced" area may be needed through the day as informed by 12Z and later guidance, as well as mesoscale analytic trends. However, with longer persistence of the MCS possible across IA/MO tonight, parts of the "slight" and "marginal" equivalent probabilities have been expanded eastward. ...Southern Plains... The width of the convectively undisturbed warm sector ahead of the southern Plains dryline is still uncertain, as considerable variability exists in progs for upscale growth of convection now manifest as a small but growing cluster over the Edwards Plateau/Hill Country/Concho Valley regions. This activity may produce sporadic large hail and damaging wind as well, through the remainder of the morning, as it proceeds across portions of central TX, with wind potential conditionally increasing where aggregation of cold pools can drive strongest forward propagation. Outflow and related theta-e deficits from any resulting complex will be advected northward into north TX and OK, with ambient theta-e decreasing northward into KS. Still, a corridor of favorable moisture should advect around the west (back) side of any such cold pool today and support isolated to widely scattered dryline development from northwest TX into parts of western OK/KS. Any sustained convection arising from that process may become supercellular, with all severe modes possible, and very large/ damaging hail a strong possibility. The least-modified air by earlier activity will have surface dewpoints in the upper 60s to low 70s F beneath EML-related steep lapse rates, fostering 3000-4000 J/kg MLCAPE. Long low-level hodographs will favor splitting storms, especially in the first couple hours after initiation, with some LLJ-aided enlargement possible in the 00-03Z time frame before parcels begin to stabilize unfavorably near the surface. ...Mid-South to Mid-Atlantic and New England... Isolated to scattered thunderstorms -- sometimes in small bands or clusters -- will persist through this afternoon along/ahead of the front from the Northeast to the lower Mississippi Valley. Areas of relative concentration within this belt will depend strongly on mesoscale boundary interactions ahead of the front (outflow and differential heating, as well as a prefrontal surface trough in the Northeast). Midlevel lapse rates, intensity of diurnal heating, and boundary-layer moisture each should generally decrease with northeastward extent. This should contribute to peak/preconvective MLCAPE in the 2000-3000 J/kg range around the lower/middle Mississippi and lower Ohio Valleys to 500-1500 J/kg over parts of the Mid-Atlantic and Northeast. Somewhat favorable deep shear amidst nearly unidirectional wind profiles will support potential for occasional damaging to isolated severe gusts throughout the Atlantic Coast States part of the corridor. A patchy distribution of marginal severe (hail and wind), with some mesobeta-scale concentrations possible, is expected across the remainder of the "marginal risk" swath. ..Edwards/Goss.. 05/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Thu May 23 2024 Valid 231300Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across a broad swath of the Great Plains this afternoon into tonight, with a few tornadoes and isolated very large hail. A concentration of severe winds -- some 75 mph or more -- is expected across a portion of the central Plains this evening into tonight. ...Synopsis... In mid/upper levels, a progressive flow belt will cover much of the CONUS, to the southeast through southwest of a persistent, somewhat flattened, quasistationary cyclone over the Canadian Prairie Provinces. This cyclone is loosely attached to another that is located over northern ON, and forecast to devolve into an open-wave trough as it moves into western/southern QC by 12Z tomorrow. The southern part of a preceding vorticity lobe will brush the St. Lawrence Valley and northern New England through 00Z. Meanwhile, another mid/upper low -- now over the northern Rockies -- should become part of a strong, open-wave trough by 00Z from eastern MT to eastern UT. This trough should pivot eastward to the Dakotas and NE by 12Z. To its south, a series of low-amplitude perturbations and vorticity lobes (some convectively generated/ enhanced) occupied the extensive west-southwest flow field from the Desert Southwest to the Appalachians. One of these -- now over southern OK and north TX -- is influencing ongoing convection from southeastern OK across AR -- and will move across the Mid-South and Tennessee Valley regions into tonight. Behind it, similar perturbations are apparent in moisture-channel imagery over Chihuahua, and over southeastern AZ/southwestern NM. These should reach central and northwest TX by 00Z. At the surface, 11Z analysis showed a low over east-central/ southeastern WY near TOR, with synoptic warm front over northern SD and southern MN. As the shortwave trough approaches, the low should deepen sharply and move to near PIR by 00Z, with cold front over western NE and northeastern CO. By 12Z, the low should reach eastern ND, with the cold front to northwestern IA, southeastern NE, south-central KS, and the TX South Plains. A warm to quasistationary front was drawn across the Red River region of TX/ OK, to the lower/middle Ohio Valley, becoming a cold front over parts of PA/upstate NY. This boundary will move eastward through the northern Appalachians, New England and much of the Mid-Atlantic through the period, while diffusely shifting northward amid areas of convection over the Mid-South and southern Plains. A dryline -- initially analyzed from the Big Bend region of TX across extreme eastern NM -- will develop northward over western parts of KS/NE today while the airmass to the east moistens. This boundary also will shift eastward into the eastern TX Panhandle near the OK border, as well as northwest/west-central TX through the afternoon. ...Central/northern Plains... Scattered thunderstorms are expected this afternoon and evening along parts of the warm and cold front near the surface low, with supercells possible in the first 2-3 hours. Damaging gusts, large to very large hail and a few tornadoes are possible. With relatively strong deep-layer and frontal forcing superimposed ahead of the progressive Rockies shortwave trough, an organized band of strong-severe thunderstorms should evolve along/ahead of the cold front and move southeastward across parts of the Dakotas and NE, eventually backbuilding into northern KS tonight as the cold front overtakes the dryline. This will cause the severe threat to transition more toward wind, with a swath of significant wind (65+ kt) potentially accompanying the QLCS. A few tornadoes also are possible with embedded mesocirculations near its edge. Though not optimally moist for the time of year, a corridor of 50s to low 60s surface dewpoints should become common this afternoon between the warm and cold fronts, combining with diurnal heating and steep midlevel lapse rates to support 1500-3000 J/kg MLCAPE. 45-55 kt effective-shear magnitudes should be common, with larger values possible near the warm front and low (but also, weaker instability). This will support both early supercells and persistence of the upscale MCS into parts of the central Plains and lower Missouri Valley regions. The southern end of well-organized, severe-wind potential over KS may be limited by residual outflow air advecting into the area from the south, while the eastern/northern ends are more uncertain. Although no change was made to the area of greatest wind probabilities this cycle, some reshaping of the "enhanced" area may be needed through the day as informed by 12Z and later guidance, as well as mesoscale analytic trends. However, with longer persistence of the MCS possible across IA/MO tonight, parts of the "slight" and "marginal" equivalent probabilities have been expanded eastward. ...Southern Plains... The width of the convectively undisturbed warm sector ahead of the southern Plains dryline is still uncertain, as considerable variability exists in progs for upscale growth of convection now manifest as a small but growing cluster over the Edwards Plateau/Hill Country/Concho Valley regions. This activity may produce sporadic large hail and damaging wind as well, through the remainder of the morning, as it proceeds across portions of central TX, with wind potential conditionally increasing where aggregation of cold pools can drive strongest forward propagation. Outflow and related theta-e deficits from any resulting complex will be advected northward into north TX and OK, with ambient theta-e decreasing northward into KS. Still, a corridor of favorable moisture should advect around the west (back) side of any such cold pool today and support isolated to widely scattered dryline development from northwest TX into parts of western OK/KS. Any sustained convection arising from that process may become supercellular, with all severe modes possible, and very large/ damaging hail a strong possibility. The least-modified air by earlier activity will have surface dewpoints in the upper 60s to low 70s F beneath EML-related steep lapse rates, fostering 3000-4000 J/kg MLCAPE. Long low-level hodographs will favor splitting storms, especially in the first couple hours after initiation, with some LLJ-aided enlargement possible in the 00-03Z time frame before parcels begin to stabilize unfavorably near the surface. ...Mid-South to Mid-Atlantic and New England... Isolated to scattered thunderstorms -- sometimes in small bands or clusters -- will persist through this afternoon along/ahead of the front from the Northeast to the lower Mississippi Valley. Areas of relative concentration within this belt will depend strongly on mesoscale boundary interactions ahead of the front (outflow and differential heating, as well as a prefrontal surface trough in the Northeast). Midlevel lapse rates, intensity of diurnal heating, and boundary-layer moisture each should generally decrease with northeastward extent. This should contribute to peak/preconvective MLCAPE in the 2000-3000 J/kg range around the lower/middle Mississippi and lower Ohio Valleys to 500-1500 J/kg over parts of the Mid-Atlantic and Northeast. Somewhat favorable deep shear amidst nearly unidirectional wind profiles will support potential for occasional damaging to isolated severe gusts throughout the Atlantic Coast States part of the corridor. A patchy distribution of marginal severe (hail and wind), with some mesobeta-scale concentrations possible, is expected across the remainder of the "marginal risk" swath. ..Edwards/Goss.. 05/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Thu May 23 2024 Valid 231300Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across a broad swath of the Great Plains this afternoon into tonight, with a few tornadoes and isolated very large hail. A concentration of severe winds -- some 75 mph or more -- is expected across a portion of the central Plains this evening into tonight. ...Synopsis... In mid/upper levels, a progressive flow belt will cover much of the CONUS, to the southeast through southwest of a persistent, somewhat flattened, quasistationary cyclone over the Canadian Prairie Provinces. This cyclone is loosely attached to another that is located over northern ON, and forecast to devolve into an open-wave trough as it moves into western/southern QC by 12Z tomorrow. The southern part of a preceding vorticity lobe will brush the St. Lawrence Valley and northern New England through 00Z. Meanwhile, another mid/upper low -- now over the northern Rockies -- should become part of a strong, open-wave trough by 00Z from eastern MT to eastern UT. This trough should pivot eastward to the Dakotas and NE by 12Z. To its south, a series of low-amplitude perturbations and vorticity lobes (some convectively generated/ enhanced) occupied the extensive west-southwest flow field from the Desert Southwest to the Appalachians. One of these -- now over southern OK and north TX -- is influencing ongoing convection from southeastern OK across AR -- and will move across the Mid-South and Tennessee Valley regions into tonight. Behind it, similar perturbations are apparent in moisture-channel imagery over Chihuahua, and over southeastern AZ/southwestern NM. These should reach central and northwest TX by 00Z. At the surface, 11Z analysis showed a low over east-central/ southeastern WY near TOR, with synoptic warm front over northern SD and southern MN. As the shortwave trough approaches, the low should deepen sharply and move to near PIR by 00Z, with cold front over western NE and northeastern CO. By 12Z, the low should reach eastern ND, with the cold front to northwestern IA, southeastern NE, south-central KS, and the TX South Plains. A warm to quasistationary front was drawn across the Red River region of TX/ OK, to the lower/middle Ohio Valley, becoming a cold front over parts of PA/upstate NY. This boundary will move eastward through the northern Appalachians, New England and much of the Mid-Atlantic through the period, while diffusely shifting northward amid areas of convection over the Mid-South and southern Plains. A dryline -- initially analyzed from the Big Bend region of TX across extreme eastern NM -- will develop northward over western parts of KS/NE today while the airmass to the east moistens. This boundary also will shift eastward into the eastern TX Panhandle near the OK border, as well as northwest/west-central TX through the afternoon. ...Central/northern Plains... Scattered thunderstorms are expected this afternoon and evening along parts of the warm and cold front near the surface low, with supercells possible in the first 2-3 hours. Damaging gusts, large to very large hail and a few tornadoes are possible. With relatively strong deep-layer and frontal forcing superimposed ahead of the progressive Rockies shortwave trough, an organized band of strong-severe thunderstorms should evolve along/ahead of the cold front and move southeastward across parts of the Dakotas and NE, eventually backbuilding into northern KS tonight as the cold front overtakes the dryline. This will cause the severe threat to transition more toward wind, with a swath of significant wind (65+ kt) potentially accompanying the QLCS. A few tornadoes also are possible with embedded mesocirculations near its edge. Though not optimally moist for the time of year, a corridor of 50s to low 60s surface dewpoints should become common this afternoon between the warm and cold fronts, combining with diurnal heating and steep midlevel lapse rates to support 1500-3000 J/kg MLCAPE. 45-55 kt effective-shear magnitudes should be common, with larger values possible near the warm front and low (but also, weaker instability). This will support both early supercells and persistence of the upscale MCS into parts of the central Plains and lower Missouri Valley regions. The southern end of well-organized, severe-wind potential over KS may be limited by residual outflow air advecting into the area from the south, while the eastern/northern ends are more uncertain. Although no change was made to the area of greatest wind probabilities this cycle, some reshaping of the "enhanced" area may be needed through the day as informed by 12Z and later guidance, as well as mesoscale analytic trends. However, with longer persistence of the MCS possible across IA/MO tonight, parts of the "slight" and "marginal" equivalent probabilities have been expanded eastward. ...Southern Plains... The width of the convectively undisturbed warm sector ahead of the southern Plains dryline is still uncertain, as considerable variability exists in progs for upscale growth of convection now manifest as a small but growing cluster over the Edwards Plateau/Hill Country/Concho Valley regions. This activity may produce sporadic large hail and damaging wind as well, through the remainder of the morning, as it proceeds across portions of central TX, with wind potential conditionally increasing where aggregation of cold pools can drive strongest forward propagation. Outflow and related theta-e deficits from any resulting complex will be advected northward into north TX and OK, with ambient theta-e decreasing northward into KS. Still, a corridor of favorable moisture should advect around the west (back) side of any such cold pool today and support isolated to widely scattered dryline development from northwest TX into parts of western OK/KS. Any sustained convection arising from that process may become supercellular, with all severe modes possible, and very large/ damaging hail a strong possibility. The least-modified air by earlier activity will have surface dewpoints in the upper 60s to low 70s F beneath EML-related steep lapse rates, fostering 3000-4000 J/kg MLCAPE. Long low-level hodographs will favor splitting storms, especially in the first couple hours after initiation, with some LLJ-aided enlargement possible in the 00-03Z time frame before parcels begin to stabilize unfavorably near the surface. ...Mid-South to Mid-Atlantic and New England... Isolated to scattered thunderstorms -- sometimes in small bands or clusters -- will persist through this afternoon along/ahead of the front from the Northeast to the lower Mississippi Valley. Areas of relative concentration within this belt will depend strongly on mesoscale boundary interactions ahead of the front (outflow and differential heating, as well as a prefrontal surface trough in the Northeast). Midlevel lapse rates, intensity of diurnal heating, and boundary-layer moisture each should generally decrease with northeastward extent. This should contribute to peak/preconvective MLCAPE in the 2000-3000 J/kg range around the lower/middle Mississippi and lower Ohio Valleys to 500-1500 J/kg over parts of the Mid-Atlantic and Northeast. Somewhat favorable deep shear amidst nearly unidirectional wind profiles will support potential for occasional damaging to isolated severe gusts throughout the Atlantic Coast States part of the corridor. A patchy distribution of marginal severe (hail and wind), with some mesobeta-scale concentrations possible, is expected across the remainder of the "marginal risk" swath. ..Edwards/Goss.. 05/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0757 AM CDT Thu May 23 2024 Valid 231300Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms are possible across a broad swath of the Great Plains this afternoon into tonight, with a few tornadoes and isolated very large hail. A concentration of severe winds -- some 75 mph or more -- is expected across a portion of the central Plains this evening into tonight. ...Synopsis... In mid/upper levels, a progressive flow belt will cover much of the CONUS, to the southeast through southwest of a persistent, somewhat flattened, quasistationary cyclone over the Canadian Prairie Provinces. This cyclone is loosely attached to another that is located over northern ON, and forecast to devolve into an open-wave trough as it moves into western/southern QC by 12Z tomorrow. The southern part of a preceding vorticity lobe will brush the St. Lawrence Valley and northern New England through 00Z. Meanwhile, another mid/upper low -- now over the northern Rockies -- should become part of a strong, open-wave trough by 00Z from eastern MT to eastern UT. This trough should pivot eastward to the Dakotas and NE by 12Z. To its south, a series of low-amplitude perturbations and vorticity lobes (some convectively generated/ enhanced) occupied the extensive west-southwest flow field from the Desert Southwest to the Appalachians. One of these -- now over southern OK and north TX -- is influencing ongoing convection from southeastern OK across AR -- and will move across the Mid-South and Tennessee Valley regions into tonight. Behind it, similar perturbations are apparent in moisture-channel imagery over Chihuahua, and over southeastern AZ/southwestern NM. These should reach central and northwest TX by 00Z. At the surface, 11Z analysis showed a low over east-central/ southeastern WY near TOR, with synoptic warm front over northern SD and southern MN. As the shortwave trough approaches, the low should deepen sharply and move to near PIR by 00Z, with cold front over western NE and northeastern CO. By 12Z, the low should reach eastern ND, with the cold front to northwestern IA, southeastern NE, south-central KS, and the TX South Plains. A warm to quasistationary front was drawn across the Red River region of TX/ OK, to the lower/middle Ohio Valley, becoming a cold front over parts of PA/upstate NY. This boundary will move eastward through the northern Appalachians, New England and much of the Mid-Atlantic through the period, while diffusely shifting northward amid areas of convection over the Mid-South and southern Plains. A dryline -- initially analyzed from the Big Bend region of TX across extreme eastern NM -- will develop northward over western parts of KS/NE today while the airmass to the east moistens. This boundary also will shift eastward into the eastern TX Panhandle near the OK border, as well as northwest/west-central TX through the afternoon. ...Central/northern Plains... Scattered thunderstorms are expected this afternoon and evening along parts of the warm and cold front near the surface low, with supercells possible in the first 2-3 hours. Damaging gusts, large to very large hail and a few tornadoes are possible. With relatively strong deep-layer and frontal forcing superimposed ahead of the progressive Rockies shortwave trough, an organized band of strong-severe thunderstorms should evolve along/ahead of the cold front and move southeastward across parts of the Dakotas and NE, eventually backbuilding into northern KS tonight as the cold front overtakes the dryline. This will cause the severe threat to transition more toward wind, with a swath of significant wind (65+ kt) potentially accompanying the QLCS. A few tornadoes also are possible with embedded mesocirculations near its edge. Though not optimally moist for the time of year, a corridor of 50s to low 60s surface dewpoints should become common this afternoon between the warm and cold fronts, combining with diurnal heating and steep midlevel lapse rates to support 1500-3000 J/kg MLCAPE. 45-55 kt effective-shear magnitudes should be common, with larger values possible near the warm front and low (but also, weaker instability). This will support both early supercells and persistence of the upscale MCS into parts of the central Plains and lower Missouri Valley regions. The southern end of well-organized, severe-wind potential over KS may be limited by residual outflow air advecting into the area from the south, while the eastern/northern ends are more uncertain. Although no change was made to the area of greatest wind probabilities this cycle, some reshaping of the "enhanced" area may be needed through the day as informed by 12Z and later guidance, as well as mesoscale analytic trends. However, with longer persistence of the MCS possible across IA/MO tonight, parts of the "slight" and "marginal" equivalent probabilities have been expanded eastward. ...Southern Plains... The width of the convectively undisturbed warm sector ahead of the southern Plains dryline is still uncertain, as considerable variability exists in progs for upscale growth of convection now manifest as a small but growing cluster over the Edwards Plateau/Hill Country/Concho Valley regions. This activity may produce sporadic large hail and damaging wind as well, through the remainder of the morning, as it proceeds across portions of central TX, with wind potential conditionally increasing where aggregation of cold pools can drive strongest forward propagation. Outflow and related theta-e deficits from any resulting complex will be advected northward into north TX and OK, with ambient theta-e decreasing northward into KS. Still, a corridor of favorable moisture should advect around the west (back) side of any such cold pool today and support isolated to widely scattered dryline development from northwest TX into parts of western OK/KS. Any sustained convection arising from that process may become supercellular, with all severe modes possible, and very large/ damaging hail a strong possibility. The least-modified air by earlier activity will have surface dewpoints in the upper 60s to low 70s F beneath EML-related steep lapse rates, fostering 3000-4000 J/kg MLCAPE. Long low-level hodographs will favor splitting storms, especially in the first couple hours after initiation, with some LLJ-aided enlargement possible in the 00-03Z time frame before parcels begin to stabilize unfavorably near the surface. ...Mid-South to Mid-Atlantic and New England... Isolated to scattered thunderstorms -- sometimes in small bands or clusters -- will persist through this afternoon along/ahead of the front from the Northeast to the lower Mississippi Valley. Areas of relative concentration within this belt will depend strongly on mesoscale boundary interactions ahead of the front (outflow and differential heating, as well as a prefrontal surface trough in the Northeast). Midlevel lapse rates, intensity of diurnal heating, and boundary-layer moisture each should generally decrease with northeastward extent. This should contribute to peak/preconvective MLCAPE in the 2000-3000 J/kg range around the lower/middle Mississippi and lower Ohio Valleys to 500-1500 J/kg over parts of the Mid-Atlantic and Northeast. Somewhat favorable deep shear amidst nearly unidirectional wind profiles will support potential for occasional damaging to isolated severe gusts throughout the Atlantic Coast States part of the corridor. A patchy distribution of marginal severe (hail and wind), with some mesobeta-scale concentrations possible, is expected across the remainder of the "marginal risk" swath. ..Edwards/Goss.. 05/23/2024 Read more

000
ABPZ20 KNHC 231117
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Thu May 23 2024

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

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

$$
Forecaster Pasch

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CDT Thu May 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... ...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys... A regional severe weather episode is expected on Day 4/Sunday. Significant severe thunderstorms capable of all hazards will be possible. An upper trough will overspread the region, resulting in a corridor of strong southwesterly mid/upper flow overlapping a very moist and strongly unstable airmass. Forecast guidance depicts a 700 mb southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley vicinity. Meanwhile, a surface low near northeast KS/northwest MO at the beginning of the period will deepen as it lifts northeast toward Lake Michigan through the evening. A cold front will develop east across the region from late afternoon into the overnight hours. Ahead of the front, mid/upper 60s F dewpoints are expected. Steep midlevel lapse rates atop this moist boundary layer will support strong destabilization. Convection will likely be ongoing Sunday morning across parts of the Mid-MS/Lower MO Valley. The evolution of this activity is a bit uncertain, but may continue to develop east along a warm front draped across northern IL/IN. Additional convection is expected across the warm sector from southeast MO/northwest AR eastward into TN/KY. While storm mode/evolution remains a bit uncertain at this time (may be a mix of supercells and more linear convection), supercell wind profiles coupled with favorable thermodynamics will support all-hazards severe potential across a broad area during the day and into the nighttime hours. ...Day 5/Mon - Mid-Atlantic to the Southeast... Spread among forecast guidance increases considerably on Monday and various models evolve the central U.S. upper trough quite a bit differently. If a more progressive system prevails, favorable vertical shear and large-scale ascent will overspread parts of the Mid-Atlantic vicinity (decreasing with southward extent into the Southeast). Severe-storm potential may develop ahead of an east/southeastward-advancing cold front if this scenario unfolds. However, uncertainty precludes introduction of 15 percent severe probabilities at this time. ...Days 6-8/Tue-Thu... Forecast spread increases further late in the period. Overall severe potential appears to wane for much of the CONUS during this time, but predictability is low. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu May 23 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN KANSAS...OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Potentially significant severe thunderstorms are expected across portions of the the central and southern Plains vicinity on Saturday. All severe hazards are possible, including a couple strong tornadoes, damaging gusts and large to very large hail. ...Central/Southern Plains to the Ozarks... A potentially significant severe-weather episode is possible on Saturday, especially from near the Red River northward across much of OK and into eastern KS. All severe hazards are expected. An upper trough over the western U.S. is expected to shift east over the Plains. As this occurs, deep-layer southwesterly flow will increase over the region. A 500 mb jet around 60-70 kt is forecast along with an area of strong upper divergence. At the surface, a warm front is expected to lift quickly northward as southerly low-level flow increases in response to deepening low pressure over the southern High Plains. The warm front should impinge on southeast NE by 00z, extending east/southeast along the I-70 corridor. The warm front will continue to lift northward into IA overnight. Meanwhile, a sharpening dryline will extend southward from west-central KS to western OK and central TX. Surface dewpoints in the low 70s F will extend north into southern KS (and east across the Ozarks), with 60s F into southern NE/IA. Very steep midlevel lapse rates will also overspread the region, aiding in strong to extreme destabilization. By 21-00z large-scale ascent is expected to overspread the dryline and northward-advancing warm front. Convective coverage is a bit uncertain, but at least widely scattered storms are expected. Nevertheless, an increasing low-level jet (850 mb southwesterly winds 45-60 kt) and vertically veering wind profiles will support supercells. Given expected instability, development may be rapid and intense, with storms quickly becoming severe. Strong tornadoes, very large hail and damaging gusts are all possible, particularly from near the Red River into OK and eastern KS. It is possible with time that one or more bowing segments will develop by late evening into the overnight hours as convection spreads east into the Ozarks. Damaging wind and QLCS tornado potential will accompany this activity. ...TN Valley to the Carolinas and Virginia... Modest northwesterly flow aloft will overspread the region on Saturday. A very moist and unstable airmass will present, supporting diurnal thunderstorm activity. Deep boundary-layer mixing and effective shear around 20-30 kt amid 1500-2500 J/kg MLCAPE will support sporadic strong storms capable of locally strong gusts. ..Leitman.. 05/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu May 23 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN KANSAS...OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Potentially significant severe thunderstorms are expected across portions of the the central and southern Plains vicinity on Saturday. All severe hazards are possible, including a couple strong tornadoes, damaging gusts and large to very large hail. ...Central/Southern Plains to the Ozarks... A potentially significant severe-weather episode is possible on Saturday, especially from near the Red River northward across much of OK and into eastern KS. All severe hazards are expected. An upper trough over the western U.S. is expected to shift east over the Plains. As this occurs, deep-layer southwesterly flow will increase over the region. A 500 mb jet around 60-70 kt is forecast along with an area of strong upper divergence. At the surface, a warm front is expected to lift quickly northward as southerly low-level flow increases in response to deepening low pressure over the southern High Plains. The warm front should impinge on southeast NE by 00z, extending east/southeast along the I-70 corridor. The warm front will continue to lift northward into IA overnight. Meanwhile, a sharpening dryline will extend southward from west-central KS to western OK and central TX. Surface dewpoints in the low 70s F will extend north into southern KS (and east across the Ozarks), with 60s F into southern NE/IA. Very steep midlevel lapse rates will also overspread the region, aiding in strong to extreme destabilization. By 21-00z large-scale ascent is expected to overspread the dryline and northward-advancing warm front. Convective coverage is a bit uncertain, but at least widely scattered storms are expected. Nevertheless, an increasing low-level jet (850 mb southwesterly winds 45-60 kt) and vertically veering wind profiles will support supercells. Given expected instability, development may be rapid and intense, with storms quickly becoming severe. Strong tornadoes, very large hail and damaging gusts are all possible, particularly from near the Red River into OK and eastern KS. It is possible with time that one or more bowing segments will develop by late evening into the overnight hours as convection spreads east into the Ozarks. Damaging wind and QLCS tornado potential will accompany this activity. ...TN Valley to the Carolinas and Virginia... Modest northwesterly flow aloft will overspread the region on Saturday. A very moist and unstable airmass will present, supporting diurnal thunderstorm activity. Deep boundary-layer mixing and effective shear around 20-30 kt amid 1500-2500 J/kg MLCAPE will support sporadic strong storms capable of locally strong gusts. ..Leitman.. 05/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu May 23 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN KANSAS...OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Potentially significant severe thunderstorms are expected across portions of the the central and southern Plains vicinity on Saturday. All severe hazards are possible, including a couple strong tornadoes, damaging gusts and large to very large hail. ...Central/Southern Plains to the Ozarks... A potentially significant severe-weather episode is possible on Saturday, especially from near the Red River northward across much of OK and into eastern KS. All severe hazards are expected. An upper trough over the western U.S. is expected to shift east over the Plains. As this occurs, deep-layer southwesterly flow will increase over the region. A 500 mb jet around 60-70 kt is forecast along with an area of strong upper divergence. At the surface, a warm front is expected to lift quickly northward as southerly low-level flow increases in response to deepening low pressure over the southern High Plains. The warm front should impinge on southeast NE by 00z, extending east/southeast along the I-70 corridor. The warm front will continue to lift northward into IA overnight. Meanwhile, a sharpening dryline will extend southward from west-central KS to western OK and central TX. Surface dewpoints in the low 70s F will extend north into southern KS (and east across the Ozarks), with 60s F into southern NE/IA. Very steep midlevel lapse rates will also overspread the region, aiding in strong to extreme destabilization. By 21-00z large-scale ascent is expected to overspread the dryline and northward-advancing warm front. Convective coverage is a bit uncertain, but at least widely scattered storms are expected. Nevertheless, an increasing low-level jet (850 mb southwesterly winds 45-60 kt) and vertically veering wind profiles will support supercells. Given expected instability, development may be rapid and intense, with storms quickly becoming severe. Strong tornadoes, very large hail and damaging gusts are all possible, particularly from near the Red River into OK and eastern KS. It is possible with time that one or more bowing segments will develop by late evening into the overnight hours as convection spreads east into the Ozarks. Damaging wind and QLCS tornado potential will accompany this activity. ...TN Valley to the Carolinas and Virginia... Modest northwesterly flow aloft will overspread the region on Saturday. A very moist and unstable airmass will present, supporting diurnal thunderstorm activity. Deep boundary-layer mixing and effective shear around 20-30 kt amid 1500-2500 J/kg MLCAPE will support sporadic strong storms capable of locally strong gusts. ..Leitman.. 05/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu May 23 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN KANSAS...OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Potentially significant severe thunderstorms are expected across portions of the the central and southern Plains vicinity on Saturday. All severe hazards are possible, including a couple strong tornadoes, damaging gusts and large to very large hail. ...Central/Southern Plains to the Ozarks... A potentially significant severe-weather episode is possible on Saturday, especially from near the Red River northward across much of OK and into eastern KS. All severe hazards are expected. An upper trough over the western U.S. is expected to shift east over the Plains. As this occurs, deep-layer southwesterly flow will increase over the region. A 500 mb jet around 60-70 kt is forecast along with an area of strong upper divergence. At the surface, a warm front is expected to lift quickly northward as southerly low-level flow increases in response to deepening low pressure over the southern High Plains. The warm front should impinge on southeast NE by 00z, extending east/southeast along the I-70 corridor. The warm front will continue to lift northward into IA overnight. Meanwhile, a sharpening dryline will extend southward from west-central KS to western OK and central TX. Surface dewpoints in the low 70s F will extend north into southern KS (and east across the Ozarks), with 60s F into southern NE/IA. Very steep midlevel lapse rates will also overspread the region, aiding in strong to extreme destabilization. By 21-00z large-scale ascent is expected to overspread the dryline and northward-advancing warm front. Convective coverage is a bit uncertain, but at least widely scattered storms are expected. Nevertheless, an increasing low-level jet (850 mb southwesterly winds 45-60 kt) and vertically veering wind profiles will support supercells. Given expected instability, development may be rapid and intense, with storms quickly becoming severe. Strong tornadoes, very large hail and damaging gusts are all possible, particularly from near the Red River into OK and eastern KS. It is possible with time that one or more bowing segments will develop by late evening into the overnight hours as convection spreads east into the Ozarks. Damaging wind and QLCS tornado potential will accompany this activity. ...TN Valley to the Carolinas and Virginia... Modest northwesterly flow aloft will overspread the region on Saturday. A very moist and unstable airmass will present, supporting diurnal thunderstorm activity. Deep boundary-layer mixing and effective shear around 20-30 kt amid 1500-2500 J/kg MLCAPE will support sporadic strong storms capable of locally strong gusts. ..Leitman.. 05/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu May 23 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN KANSAS...OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Potentially significant severe thunderstorms are expected across portions of the the central and southern Plains vicinity on Saturday. All severe hazards are possible, including a couple strong tornadoes, damaging gusts and large to very large hail. ...Central/Southern Plains to the Ozarks... A potentially significant severe-weather episode is possible on Saturday, especially from near the Red River northward across much of OK and into eastern KS. All severe hazards are expected. An upper trough over the western U.S. is expected to shift east over the Plains. As this occurs, deep-layer southwesterly flow will increase over the region. A 500 mb jet around 60-70 kt is forecast along with an area of strong upper divergence. At the surface, a warm front is expected to lift quickly northward as southerly low-level flow increases in response to deepening low pressure over the southern High Plains. The warm front should impinge on southeast NE by 00z, extending east/southeast along the I-70 corridor. The warm front will continue to lift northward into IA overnight. Meanwhile, a sharpening dryline will extend southward from west-central KS to western OK and central TX. Surface dewpoints in the low 70s F will extend north into southern KS (and east across the Ozarks), with 60s F into southern NE/IA. Very steep midlevel lapse rates will also overspread the region, aiding in strong to extreme destabilization. By 21-00z large-scale ascent is expected to overspread the dryline and northward-advancing warm front. Convective coverage is a bit uncertain, but at least widely scattered storms are expected. Nevertheless, an increasing low-level jet (850 mb southwesterly winds 45-60 kt) and vertically veering wind profiles will support supercells. Given expected instability, development may be rapid and intense, with storms quickly becoming severe. Strong tornadoes, very large hail and damaging gusts are all possible, particularly from near the Red River into OK and eastern KS. It is possible with time that one or more bowing segments will develop by late evening into the overnight hours as convection spreads east into the Ozarks. Damaging wind and QLCS tornado potential will accompany this activity. ...TN Valley to the Carolinas and Virginia... Modest northwesterly flow aloft will overspread the region on Saturday. A very moist and unstable airmass will present, supporting diurnal thunderstorm activity. Deep boundary-layer mixing and effective shear around 20-30 kt amid 1500-2500 J/kg MLCAPE will support sporadic strong storms capable of locally strong gusts. ..Leitman.. 05/23/2024 Read more

MD 0906 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTH-CENTRAL AND SOUTHEASTERN OKLAHOMA...AND INTO WESTERN ARKANSAS
Mesoscale Discussion 0906 NWS Storm Prediction Center Norman OK 0207 AM CDT Thu May 23 2024 Areas affected...south-central and southeastern Oklahoma...and into western Arkansas Concerning...Severe potential...Watch unlikely Valid 230707Z - 230900Z Probability of Watch Issuance...20 percent SUMMARY...A few strong/locally severe storms will likely persist over the next few hours. Hail in the 1" to 1.75" range, and possibly a strong/damaging gust or two, will be possible with the strongest storms. DISCUSSION...Latest radar loop shows a gradually expanding cluster of storms over south-central Oklahoma. The storms are not well-depicted by any recent CAM runs, but are occurring in tandem with a weak cyclonic mid-level circulation evident in water vapor imagery, and near the nose of an associated 40 kt southerly low-level jet. The resulting QG forcing, co-located with an axis of 1500 to 2000 J/kg slightly elevated CAPE, should allow continuance of the ongoing storms, and possibly a minor increase in storm coverage. Latest area VWP data shows weakly veering flow through the cloud-bearing layer (roughly 850mb to 150 mb), that increases with height -- particularly at mid to upper levels. The resulting effective-layer (LCL to mid-cloud depth) supports potential for organized/rotating storms. With storms slightly elevated atop a modestly stable layer, primary risk should remain large hail, though a stronger gust or two cannot be ruled out. Overall, with risk expected to remain isolated to a couple of the strongest storms, current expectations are that wW issuance should remain unnecessary. ..Goss/Edwards.. 05/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LZK...SHV...TSA...FWD...OUN... LAT...LON 34389803 34829789 35359650 35959465 35749371 35019372 34669365 34169318 33539344 33759562 34389803 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Thu May 23 2024 Valid 241200Z - 251200Z ...Synopsis... A large-scale trough will progress eastward across the central and western CONUS Friday, while a related belt of moderate westerlies aloft overspreads a dry and deeply mixed air mass over the Southwest. A mid-level shortwave trough digging near the Pacific coastline will move onshore near central CA and the Great Basin, promoting a deepening surface low just ahead of it. A tightening surface pressure gradient will yield breezy surface winds late Friday afternoon into early Friday evening, and combine with low RH across much of AZ and NM. The highest chances for a few hours of critical fire weather conditions will likely develop over northeast AZ and far western NM. However, these conditions will only overlap a small area of receptive fuels. Therefore, the Critical area has been removed for the aforementioned region. ..Barnes.. 05/23/2024 ...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 0202 AM CDT Thu May 23 2024 Valid 241200Z - 251200Z ...Synopsis... A large-scale trough will progress eastward across the central and western CONUS Friday, while a related belt of moderate westerlies aloft overspreads a dry and deeply mixed air mass over the Southwest. A mid-level shortwave trough digging near the Pacific coastline will move onshore near central CA and the Great Basin, promoting a deepening surface low just ahead of it. A tightening surface pressure gradient will yield breezy surface winds late Friday afternoon into early Friday evening, and combine with low RH across much of AZ and NM. The highest chances for a few hours of critical fire weather conditions will likely develop over northeast AZ and far western NM. However, these conditions will only overlap a small area of receptive fuels. Therefore, the Critical area has been removed for the aforementioned region. ..Barnes.. 05/23/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more