Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1026 AM CST Tue Feb 27 2024 Valid 271630Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PORTIONS OF THE LOWER AND MIDDLE OHIO VALLEY...AND ACROSS A SMALL PART OF NORTHERN ILLINOIS AND SOUTHEAST WISCONSIN... ...SUMMARY... Severe thunderstorms, associated with large hail, damaging gusts, and tornadoes, some of which may be significant, will be possible from late this afternoon into the overnight, across portions of the Ohio Valley and southern Great Lakes. ...OH Valley... A fast-moving southern-stream shortwave trough over the central Plains will track eastward today and begin affecting parts of MO by late afternoon or early evening. Most 12z guidance suggests that at least isolated thunderstorm development will begin around/after dusk as the large-scale forcing overspreads the northern extent of moist/unstable air mass from southwest MO into southern IL. These storms will intensify and track eastward overnight roughly along the OH river, moving into parts of OH/WV/PA by early morning Wednesday. Initial storms may be discrete, with sufficient vertical shear for supercells structures capable of all severe hazards. As the night progresses, activity will likely evolve into fast-moving bowing structures with an enhanced risk of damaging wind gusts and a few tornadoes. A strong tornado or two cannot be ruled out. Have added an ENH risk area for this scenario overnight. ...IL/WI... A compact surface low is forecast to deepen across eastern IA this afternoon, with a narrow warm sector pulling northward into much of northern IL. Strong forcing near the low and along the associated warm front will lead to intense thunderstorms across portions of northern IL after 22z. Forecast soundings show steep low and mid level lapse rates and sufficient CAPE, along with strong low and deep layer shear profiles. This will be conducive to supercell structures capable of very large hail and damaging winds. There remains uncertainty whether these storms will be in the warm-sector, or will be undercut by nearby cold air. Have upgraded a small part of this area to ENH risk for hail, but there is also concern for tornadoes if the activity remains surface-based. ..Hart/Bentley.. 02/27/2024 Read more

MD 0159 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL AND EASTERN KENTUCKY...NORTHERN TENNESSEE
Mesoscale Discussion 0159 NWS Storm Prediction Center Norman OK 0542 AM CST Tue Feb 27 2024 Areas affected...Central and Eastern Kentucky...Northern Tennessee Concerning...Severe potential...Watch unlikely Valid 271142Z - 271415Z Probability of Watch Issuance...20 percent SUMMARY...A threat for marginally severe hail may develop over parts of central and eastern Kentucky this morning. The magnitude of the hail threat should remain too small for weather watch issuance. DISCUSSION...The latest water vapor imagery shows a patch of maximized mid-level moisture associated with a shortwave trough, located across the Ohio and Tennessee Valleys. Scattered thunderstorms are ongoing with this area ahead of the shortwave trough over far southern Indiana, central Kentucky and middle Tennessee. Mesoscale analysis in central Kentucky has MUCAPE approaching 1000 J/kg, with 700-500 mb lapse rates in the 7 to 7.5 C/km range. In addition, RAP forecast soundings in central Kentucky have a steep temperature inversion from the surface to 850 mb, with effective shear near 50 knots. This suggests some potential for a couple elevated rotating storms capable of marginally severe hail. The threat should continue into the mid to late morning as scattered strong thunderstorms move eastward into eastern Kentucky. ..Broyles/Goss.. 02/27/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RLX...MRX...JKL...ILN...LMK...OHX... LAT...LON 37038276 36568302 36288350 36188420 36158519 36378584 36848613 37508617 38078599 38438545 38508451 38398340 38228295 37858265 37038276 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Tue Feb 27 2024 Valid 271300Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST VICINITY... ...SUMMARY... Scattered strong to severe thunderstorms, associated with large hail (some 2 inches diameter), damaging gusts, and a few tornadoes will be possible from late this afternoon into the evening and overnight, from parts of the mid Mississippi Valley to the Ohio Valley and southern Great Lakes. ...Synopsis... A progressive upper trough over the western U.S. this morning is forecast to advance steadily eastward into/across the Plains this afternoon and evening, and then onward toward the Mid and Upper Mississippi Valley overnight. In tandem with the advance of this feature, a strengthening surface cold front currently stretching from the Upper Mississippi Valley to northeastern Colorado will continue plunging southeastward across the Plains through the day. A somewhat ill-defined frontal low will gradually consolidate into this evening over the northern Illinois vicinity, moving northeastward across Lower Michigan overnight. As it does, the trailing cold front will continue to surge southward/southeastward into/across the Midwest/Mid Mississippi Valley/Southern Plains overnight. By 12Z Wednesday, the front should extend from Lake Huron, south across the Middle Ohio Valley, and then southwestward across the Tennessee valley to the Texas Coastal Plain. ...The Midwest vicinity... Ahead of the advancing cold front, southerly low-level flow will continue to advect low-level moisture northward, beneath a low-level inversion/cap evident in morning RAOBs from the southern Plains into the Midwest. Evolution of this gradually moistening but capped low-level airmass will likely be a key determinant with respect to degree of convective evolution -- and the intensity thereof -- late this afternoon/and this evening. Low-level airmass concerns aside, the evolving scenario otherwise remains favorable for severe potential across the Midwest and vicinity. Steep lapse rates are evident above the low-level inversion, and increasingly strong deep-layer flow will accompany the advance of the upper system, and gradual consolidation of the surface frontal low. As such, from a broad dynamic and kinematic perspective, the pattern continues to appear favorable. Thermodynamically, there remain concerns that the boundary layer will remain somewhat cool/stable, relative to the warmer air in the roughly 900 to 800 mb layer. Further, heating/mixing will also result in mixing out, to some degree, of the shallow surface-based moisture returning northward on low-level southerly flow within the developing warm sector. With all that said, 500 to 1000 J/kg mixed-layer CAPE should characterize the boundary layer by late afternoon/early evening, as the front approaches. This will result in isolated to scattered storm development -- initially over the northern Illinois vicinity but later farther south nearer the Ohio Valley -- possibly in a somewhat bimodal manner with a relative minimum in between. Eventually, through mid to late evening, increasingly widespread storms should be expanding across the Midwest/Ohio Valley region, which will then continue eastward across the Upper Ohio Valley and toward the central Appalachians through the end of the period. Given the favorable kinematic environment, at least isolated organized/rotating storms are expected, with some upscale growth into bands possibly occurring overnight and spreading eastward with time. Along with potential for large hail -- locally near 2" in diameter, locally strong/damaging wind gusts are also expect with stronger storms/storm clusters. Additionally, a few tornadoes may also occur, though uncertainties regarding low-level moisture/instability suggest overall tornado potential should remain limited. ..Goss/Broyles.. 02/27/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Tue Feb 27 2024 Valid 011200Z - 061200Z ...DISCUSSION... Thunderstorm chances will likely continue across the Gulf Coast States/Southeast on Days 4-5/Fri-Sat as a series of weak/low-amplitude upper shortwave troughs migrate across the region. In the low-levels this area will remain under the influence of high pressure and any deeper boundary-layer moisture will remain confined to the immediate coastal areas, with limited inland destabilization. Coupled with weak vertical shear, severe storms are not anticipated. By Days 6-7/Sun-Mon, spread in medium range guidance has increased over the past 24 hours. During this time, an upper trough over the western U.S. is forecast to emerge into the central U.S. However, forecast guidance handles the eastward evolution of the trough very differently. The ECMWF progresses a much lower-amplitude trough eastward across the central Plains to the Upper Midwest, while a secondary, weaker, southern stream shortwave trough moves across TX into the Lower MS Valley. Meanwhile, the GFS maintains its solution of a deeper, more neutral to negatively tilted upper trough traversing the Plains and MS Valley. These differences in the upper pattern have large impacts on surface cyclogenesis, cold front position/timing and quality of low-level moisture return. While some severe potential may develop in this general pattern somewhere from the central/southern Plains to the Mid/Lower MS Valley, uncertainty in most favorable location and timing remains too high to include 15 percent probabilities at this time for the Days 6-7/Sun-Mon time period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Tue Feb 27 2024 Valid 011200Z - 061200Z ...DISCUSSION... Thunderstorm chances will likely continue across the Gulf Coast States/Southeast on Days 4-5/Fri-Sat as a series of weak/low-amplitude upper shortwave troughs migrate across the region. In the low-levels this area will remain under the influence of high pressure and any deeper boundary-layer moisture will remain confined to the immediate coastal areas, with limited inland destabilization. Coupled with weak vertical shear, severe storms are not anticipated. By Days 6-7/Sun-Mon, spread in medium range guidance has increased over the past 24 hours. During this time, an upper trough over the western U.S. is forecast to emerge into the central U.S. However, forecast guidance handles the eastward evolution of the trough very differently. The ECMWF progresses a much lower-amplitude trough eastward across the central Plains to the Upper Midwest, while a secondary, weaker, southern stream shortwave trough moves across TX into the Lower MS Valley. Meanwhile, the GFS maintains its solution of a deeper, more neutral to negatively tilted upper trough traversing the Plains and MS Valley. These differences in the upper pattern have large impacts on surface cyclogenesis, cold front position/timing and quality of low-level moisture return. While some severe potential may develop in this general pattern somewhere from the central/southern Plains to the Mid/Lower MS Valley, uncertainty in most favorable location and timing remains too high to include 15 percent probabilities at this time for the Days 6-7/Sun-Mon time period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Tue Feb 27 2024 Valid 011200Z - 061200Z ...DISCUSSION... Thunderstorm chances will likely continue across the Gulf Coast States/Southeast on Days 4-5/Fri-Sat as a series of weak/low-amplitude upper shortwave troughs migrate across the region. In the low-levels this area will remain under the influence of high pressure and any deeper boundary-layer moisture will remain confined to the immediate coastal areas, with limited inland destabilization. Coupled with weak vertical shear, severe storms are not anticipated. By Days 6-7/Sun-Mon, spread in medium range guidance has increased over the past 24 hours. During this time, an upper trough over the western U.S. is forecast to emerge into the central U.S. However, forecast guidance handles the eastward evolution of the trough very differently. The ECMWF progresses a much lower-amplitude trough eastward across the central Plains to the Upper Midwest, while a secondary, weaker, southern stream shortwave trough moves across TX into the Lower MS Valley. Meanwhile, the GFS maintains its solution of a deeper, more neutral to negatively tilted upper trough traversing the Plains and MS Valley. These differences in the upper pattern have large impacts on surface cyclogenesis, cold front position/timing and quality of low-level moisture return. While some severe potential may develop in this general pattern somewhere from the central/southern Plains to the Mid/Lower MS Valley, uncertainty in most favorable location and timing remains too high to include 15 percent probabilities at this time for the Days 6-7/Sun-Mon time period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0300 AM CST Tue Feb 27 2024 Valid 011200Z - 061200Z ...DISCUSSION... Thunderstorm chances will likely continue across the Gulf Coast States/Southeast on Days 4-5/Fri-Sat as a series of weak/low-amplitude upper shortwave troughs migrate across the region. In the low-levels this area will remain under the influence of high pressure and any deeper boundary-layer moisture will remain confined to the immediate coastal areas, with limited inland destabilization. Coupled with weak vertical shear, severe storms are not anticipated. By Days 6-7/Sun-Mon, spread in medium range guidance has increased over the past 24 hours. During this time, an upper trough over the western U.S. is forecast to emerge into the central U.S. However, forecast guidance handles the eastward evolution of the trough very differently. The ECMWF progresses a much lower-amplitude trough eastward across the central Plains to the Upper Midwest, while a secondary, weaker, southern stream shortwave trough moves across TX into the Lower MS Valley. Meanwhile, the GFS maintains its solution of a deeper, more neutral to negatively tilted upper trough traversing the Plains and MS Valley. These differences in the upper pattern have large impacts on surface cyclogenesis, cold front position/timing and quality of low-level moisture return. While some severe potential may develop in this general pattern somewhere from the central/southern Plains to the Mid/Lower MS Valley, uncertainty in most favorable location and timing remains too high to include 15 percent probabilities at this time for the Days 6-7/Sun-Mon time period. Read more