Severe Storms

MD 2087 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTH-CENTRAL OKLAHOMA INTO EASTERN KANSAS
Mesoscale Discussion 2087 NWS Storm Prediction Center Norman OK 0317 PM CDT Thu Sep 19 2024 Areas affected...North-central Oklahoma into eastern Kansas Concerning...Severe potential...Watch possible Valid 192017Z - 192215Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorm development is anticipated by around 4-6 PM CDT across northern Oklahoma into southern/southeast Kansas. This activity may pose a severe hail/wind threat as it spreads into eastern Kansas this evening. Watch issuance may be needed later this afternoon/evening to address this concern. DISCUSSION...GOES visible imagery over the past 30 minutes has shown a steady uptick in cumulus development along a diffuse surface trough/cold front from southern KS into the eastern TX Panhandle. The 18 UTC sounding from TOP shows a stout cap remains in place across east/northeast KS, but hot temperatures across OK/southern KS in the upper 90s to low 100s are actively mixing out lingering inhibition (as evidenced by the recent deep convection along I-40 in western OK). This trend appears to be faster than depicted by recent CAM solutions, suggesting that robust initiation may occur in the coming hours across southern KS. As storms develop, they will mature in an environment characterized by MLCAPE values between 1500-2500 J/kg and 30-40 knots of effective bulk shear (based on the recent TOP sounding and latest mesosnalysis estimates). Deep-layer shear vectors largely orthogonal to the front should favor discrete cells initially with a large hail threat (most likely hail size between 1.0 to 1.75 inches), but increasing storm coverage through early evening should promote clustering with an increasing potential for severe winds (50-70 mph) as activity spreads into eastern KS. While timing remains somewhat uncertain, watch issuance may be needed late this afternoon/early evening across this region. ..Moore/Gleason.. 09/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SGF...EAX...TSA...TOP...ICT...OUN... LAT...LON 36889803 37859703 37989695 38609644 38919624 39169606 39279587 39419560 39449536 39439512 39379492 39269480 39169465 38909455 38549456 38059462 37689482 37319511 37029559 36819600 36699632 36439778 36399808 36449827 36579835 36669827 36889803 Read more

WW 0678 Status Updates
STATUS FOR WATCH 0678 HAS NOT BEEN ISSUED YET Read more

WW 0677 Status Updates
STATUS REPORT ON WW 677 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..09/19/24 ATTN...WFO...DMX...ARX...MPX... STATUS REPORT FOR WS 677 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC033-037-063-067-081-089-109-131-147-189-191-195-192140- IA . IOWA COUNTIES INCLUDED ARE CERRO GORDO CHICKASAW EMMET FLOYD HANCOCK HOWARD KOSSUTH MITCHELL PALO ALTO WINNEBAGO WINNESHIEK WORTH MNC003-013-019-025-037-039-043-045-047-049-053-055-059-079-091- 099-103-109-123-131-139-143-147-157-161-163-169-192140- MN . MINNESOTA COUNTIES INCLUDED ARE ANOKA BLUE EARTH CARVER CHISAGO DAKOTA DODGE FARIBAULT FILLMORE FREEBORN GOODHUE HENNEPIN HOUSTON ISANTI LE SUEUR MARTIN MOWER NICOLLET OLMSTED RAMSEY RICE SCOTT SIBLEY STEELE WABASHA WASECA WASHINGTON WINONA Read more

WW 0677 Status Updates
STATUS REPORT ON WW 677 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..09/19/24 ATTN...WFO...DMX...ARX...MPX... STATUS REPORT FOR WS 677 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC033-037-063-067-081-089-109-131-147-189-191-195-192140- IA . IOWA COUNTIES INCLUDED ARE CERRO GORDO CHICKASAW EMMET FLOYD HANCOCK HOWARD KOSSUTH MITCHELL PALO ALTO WINNEBAGO WINNESHIEK WORTH MNC003-013-019-025-037-039-043-045-047-049-053-055-059-079-091- 099-103-109-123-131-139-143-147-157-161-163-169-192140- MN . MINNESOTA COUNTIES INCLUDED ARE ANOKA BLUE EARTH CARVER CHISAGO DAKOTA DODGE FARIBAULT FILLMORE FREEBORN GOODHUE HENNEPIN HOUSTON ISANTI LE SUEUR MARTIN MOWER NICOLLET OLMSTED RAMSEY RICE SCOTT SIBLEY STEELE WABASHA WASECA WASHINGTON WINONA Read more

WW 0677 Status Updates
STATUS REPORT ON WW 677 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..KERR..09/19/24 ATTN...WFO...DMX...ARX...MPX... STATUS REPORT FOR WS 677 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC033-037-063-067-081-089-109-131-147-189-191-195-192140- IA . IOWA COUNTIES INCLUDED ARE CERRO GORDO CHICKASAW EMMET FLOYD HANCOCK HOWARD KOSSUTH MITCHELL PALO ALTO WINNEBAGO WINNESHIEK WORTH MNC003-013-019-025-037-039-043-045-047-049-053-055-059-079-091- 099-103-109-123-131-139-143-147-157-161-163-169-192140- MN . MINNESOTA COUNTIES INCLUDED ARE ANOKA BLUE EARTH CARVER CHISAGO DAKOTA DODGE FARIBAULT FILLMORE FREEBORN GOODHUE HENNEPIN HOUSTON ISANTI LE SUEUR MARTIN MOWER NICOLLET OLMSTED RAMSEY RICE SCOTT SIBLEY STEELE WABASHA WASECA WASHINGTON WINONA Read more

MD 2086 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PARTS OF EAST CENTRAL AND SOUTHEASTERN MINNESOTA...ADJACENT NORTHERN IOWA AND WEST CENTRAL WISCONSIN
Mesoscale Discussion 2086 NWS Storm Prediction Center Norman OK 0126 PM CDT Thu Sep 19 2024 Areas affected...parts of east central and southeastern Minnesota...adjacent northern Iowa and west central Wisconsin Concerning...Severe potential...Watch likely Valid 191826Z - 192030Z Probability of Watch Issuance...80 percent SUMMARY...Strong thunderstorm development appears increasingly likely through 3-5 PM CDT, near/northwest of the Greater Minneapolis area into areas southwest of Mankato. This probably will include the evolution of at least widely scattered supercells posing a risk for severe hail, with largest hailstones perhaps exceeding 2 inches in diameter. DISCUSSION...To the southeast of an occluded lower/mid-tropospheric cyclone, now beginning to redevelop eastward across southern Manitoba, moderately strong destabilization is ongoing. This is generally focused ahead of a residual wind shift, within a plume of higher low-level moisture content which is being maintained beneath a tongue of cool mid-level air. CAPE (up to 1500-2000 J/kg) appears maximized within a rather narrow corridor beneath steep mid-level lapse rates which roughly coincide with 500 mb temperatures around -13 to -14 C. This is forecast to continue slowly shifting across the central through eastern Minnesota vicinity through mid to late afternoon. A relative warm layer around or just below the 700 mb level is tending to suppress boundary-layer based thunderstorm initiation along the potential instability axis. However, model output is suggestive that forcing for ascent in the left exit region of an approaching jet streak, near the southern periphery of the cyclonic mid/upper flow, will contribute to thunderstorm development across southern Minnesota and adjacent northern Iowa by 20-22Z. In the presence of at least strong deep-layer shear, it appears that this will probably include widely scattered to scattered supercells, initially generally west of the Minneapolis through Mankato vicinities. These probably will pose a risk for severe hail, with largest stones perhaps exceeding 2 inches in diameter. ..Kerr/Gleason.. 09/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...ARX...MPX...DMX...FSD... LAT...LON 44949418 45939279 45289127 43599265 43039368 43259525 44949418 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Thu Sep 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST INTO EASTERN KANSAS...WESTERN MISSOURI...AND FAR NORTHEAST OKLAHOMA... ...SUMMARY... Scattered severe thunderstorms are possible this afternoon and evening across central/eastern Minnesota, Iowa, and western Wisconsin. A couple of tornadoes, large hail, and damaging winds may occur across this region. Farther south, an area of locally severe wind gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and northeast Oklahoma. ...20Z Update... The 18Z observed Minneapolis sounding showed steep mid-level lapse rates in addition to a long and predominantly straight hodograph. The expectation remains that a few supercells may initially develop from north-central Iowa into east-central Minnesota over the next 2-3 hours. These storms would pose the greatest risk for large/very-large hail. Given weak low-level shear evident on area VAD data in combination with linear forcing from the cold front, upscale growth should still occur quickly with a transition to more of a damaging wind threat. As this is in line with the thinking of the previous forecast, no changes have been made other than minor changes to the general thunderstorm area. See the previous discussion for further details. ..Wendt.. 09/19/2024 .PREV DISCUSSION... /ISSUED 1126 AM CDT Thu Sep 19 2024/ ...Minnesota/Wisconsin/Iowa... Widely spaced and mainly elevated thunderstorms ongoing late this morning across parts of IA into eastern MN and western WI should continue to diminish in coverage over the next couple of hours. In their wake, daytime heating of a seasonably moist low-level airmass (surface dewpoints generally in the 60s) and somewhat steep mid-level lapse rates will contribute to at least moderate instability by mid afternoon along/ahead of a cold front extending north to south from western MN into eastern NE and western IA. An upper low over northern ND and southeast SK/southwest MB will continue to advance slowly northeastward across south-central Canada through the period. A belt of 35-50 kt mid-level west-southwesterly winds on the southern periphery of the upper low will spread eastward from the northern Plains into the Upper Midwest through this evening. A veering/strengthening wind profile with height through mid levels will support around 30-40 kt of deep-layer shear across the warm sector. This shear will be sufficient for organized thunderstorms, including the potential for a few supercells. Current expectations are that scattered thunderstorms will develop by mid to late afternoon across central/eastern MN into northern/central IA along or just ahead of the eastward-advancing cold front. A rather favorable thermodynamic environment will foster robust updrafts, and any initial supercells should pose a threat for large to very large hail (around 1.5-2.5 inches in diameter). But, a fairly quick transition to more linear structures should occur given the presence of the cold front, with a potentially greater damaging wind threat evolving with eastward extent through the evening before convection eventually weakens. South-southwesterly low-level flow and related shear ahead of the front is not forecast to be overly strong by most guidance this afternoon. But, some threat for a couple of tornadoes remains apparent, especially with any sustained supercells across east-central/southern MN into northern IA late this afternoon/early evening. ...Eastern Kansas into Missouri and Northeast Oklahoma... An upper ridge, with rather warm mid-level temperatures, will remain centered over the southern Plains today. The surface cold front is forecast to continue moving east-southeastward across the mid MO Valley and central Plains through late this afternoon. A surface trough extending southward from this front across the southern High Plains should also mix eastward through peak daytime heating. Given weak large-scale ascent and rather warm mid-level temperatures across this area, there is still a fair amount of uncertainty regarding how many additional thunderstorms will develop later today, notwithstanding the ongoing (mainly elevated) convection over eastern KS and far northwest MO. Still, other surface-based thunderstorms may develop later this afternoon along/near the front/dryline intersection in south-central KS/north-central OK, and along the cold front in eastern KS. While low/mid-level flow should remain fairly modest, steepened low-level lapse rates and moderate instability should support a risk for mainly severe/damaging downdrafts as convection spreads east-southeastward into western MO and northeast OK through this evening. Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Thu Sep 19 2024 Valid 211200Z - 271200Z Multiple mid-level troughs will traverse the Intermountain West and eject into the central and northern Mississippi Valley through the middle of next week, encouraging surface high pressure and cooler air to gradually overspread much of the CONUS. Appreciable rainfall accumulations are likely across the southern Plains into the Ohio Valley through next week, which should help dampen very dry fuels across these regions. Approaching cooler temperatures or meaningful rainfall accumulations over much of the CONUS suggests that quiescent fire weather conditions should prevail for this upcoming week. Locally dry and breezy conditions may occur over portions of the Interior West or High Plains, but such conditions appear too localized to warrant critical probabilities this outlook. ..Squitieri.. 09/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Thu Sep 19 2024 Valid 211200Z - 271200Z Multiple mid-level troughs will traverse the Intermountain West and eject into the central and northern Mississippi Valley through the middle of next week, encouraging surface high pressure and cooler air to gradually overspread much of the CONUS. Appreciable rainfall accumulations are likely across the southern Plains into the Ohio Valley through next week, which should help dampen very dry fuels across these regions. Approaching cooler temperatures or meaningful rainfall accumulations over much of the CONUS suggests that quiescent fire weather conditions should prevail for this upcoming week. Locally dry and breezy conditions may occur over portions of the Interior West or High Plains, but such conditions appear too localized to warrant critical probabilities this outlook. ..Squitieri.. 09/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more