Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN MO...CENTRAL/EASTERN IA...SOUTHEAST MN...CENTRAL/SOUTHERN WI...NORTHWEST IL... ...SUMMARY... Severe storms will be possible across the upper Mississippi Valley and upper Midwest on Saturday. Damaging wind, isolated hail, and a tornado or two are all possible. ...East-central Great Plains into the upper Midwest... The Slight Risk has been shifted southward, based on the latest guidance regarding the likely position of the primary surface boundary during the afternoon and evening. A convectively enhanced shortwave trough is forecast to move across the upper Midwest on Saturday. In the wake of morning convection, moderate to locally strong buoyancy is expected to develop from eastern KS/southeast NE northeastward into parts of southern WI/northern IL, along/south of an outflow-reinforced front. Scattered thunderstorms are expected to develop along the front by late afternoon and spread eastward into the evening. Effective shear generally in the 30-40 kt range will support a few organized cells/clusters. Relatively strong heating and large PW will support strong/damaging gusts as the most likely hazard. Warm temperatures aloft and weak midlevel lapse rates should limit the hail threat, though isolated hail cannot be ruled out if any supercells can be sustained. A tornado or two will also be possible, in the presence of moderate low-level southwesterly flow and modestly enhanced SRH. Farther east, intensification of morning convection and/or afternoon redevelopment will be possible across parts of lower MI. While instability will be weaker compared to areas father west, somewhat enhanced low/midlevel flow will support a threat for isolated damaging wind and possibly a brief tornado. ...Parts of the Northeast... Widely scattered thunderstorms will be possible across parts of the Northeast during the afternoon and evening, within a warm, moderately unstable, and weakly capped environment along/south of a cold front draped across parts of New England. Modest midlevel west-southwesterly flow could support a few weakly organized cells/clusters capable of locally damaging wind. ...Parts of ND... A mid/upper-level shortwave trough is forecast to move across parts of SK/MB on Saturday, with some influence of this shortwave expected to extend into parts of ND. Isolated to widely scattered thunderstorm development will be possible during the afternoon/evening, with moderate buoyancy and sufficient deep-layer shear supporting potential for a few organized storms capable of isolated hail and strong/severe gusts. ..Dean.. 06/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN MO...CENTRAL/EASTERN IA...SOUTHEAST MN...CENTRAL/SOUTHERN WI...NORTHWEST IL... ...SUMMARY... Severe storms will be possible across the upper Mississippi Valley and upper Midwest on Saturday. Damaging wind, isolated hail, and a tornado or two are all possible. ...East-central Great Plains into the upper Midwest... The Slight Risk has been shifted southward, based on the latest guidance regarding the likely position of the primary surface boundary during the afternoon and evening. A convectively enhanced shortwave trough is forecast to move across the upper Midwest on Saturday. In the wake of morning convection, moderate to locally strong buoyancy is expected to develop from eastern KS/southeast NE northeastward into parts of southern WI/northern IL, along/south of an outflow-reinforced front. Scattered thunderstorms are expected to develop along the front by late afternoon and spread eastward into the evening. Effective shear generally in the 30-40 kt range will support a few organized cells/clusters. Relatively strong heating and large PW will support strong/damaging gusts as the most likely hazard. Warm temperatures aloft and weak midlevel lapse rates should limit the hail threat, though isolated hail cannot be ruled out if any supercells can be sustained. A tornado or two will also be possible, in the presence of moderate low-level southwesterly flow and modestly enhanced SRH. Farther east, intensification of morning convection and/or afternoon redevelopment will be possible across parts of lower MI. While instability will be weaker compared to areas father west, somewhat enhanced low/midlevel flow will support a threat for isolated damaging wind and possibly a brief tornado. ...Parts of the Northeast... Widely scattered thunderstorms will be possible across parts of the Northeast during the afternoon and evening, within a warm, moderately unstable, and weakly capped environment along/south of a cold front draped across parts of New England. Modest midlevel west-southwesterly flow could support a few weakly organized cells/clusters capable of locally damaging wind. ...Parts of ND... A mid/upper-level shortwave trough is forecast to move across parts of SK/MB on Saturday, with some influence of this shortwave expected to extend into parts of ND. Isolated to widely scattered thunderstorm development will be possible during the afternoon/evening, with moderate buoyancy and sufficient deep-layer shear supporting potential for a few organized storms capable of isolated hail and strong/severe gusts. ..Dean.. 06/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN MO...CENTRAL/EASTERN IA...SOUTHEAST MN...CENTRAL/SOUTHERN WI...NORTHWEST IL... ...SUMMARY... Severe storms will be possible across the upper Mississippi Valley and upper Midwest on Saturday. Damaging wind, isolated hail, and a tornado or two are all possible. ...East-central Great Plains into the upper Midwest... The Slight Risk has been shifted southward, based on the latest guidance regarding the likely position of the primary surface boundary during the afternoon and evening. A convectively enhanced shortwave trough is forecast to move across the upper Midwest on Saturday. In the wake of morning convection, moderate to locally strong buoyancy is expected to develop from eastern KS/southeast NE northeastward into parts of southern WI/northern IL, along/south of an outflow-reinforced front. Scattered thunderstorms are expected to develop along the front by late afternoon and spread eastward into the evening. Effective shear generally in the 30-40 kt range will support a few organized cells/clusters. Relatively strong heating and large PW will support strong/damaging gusts as the most likely hazard. Warm temperatures aloft and weak midlevel lapse rates should limit the hail threat, though isolated hail cannot be ruled out if any supercells can be sustained. A tornado or two will also be possible, in the presence of moderate low-level southwesterly flow and modestly enhanced SRH. Farther east, intensification of morning convection and/or afternoon redevelopment will be possible across parts of lower MI. While instability will be weaker compared to areas father west, somewhat enhanced low/midlevel flow will support a threat for isolated damaging wind and possibly a brief tornado. ...Parts of the Northeast... Widely scattered thunderstorms will be possible across parts of the Northeast during the afternoon and evening, within a warm, moderately unstable, and weakly capped environment along/south of a cold front draped across parts of New England. Modest midlevel west-southwesterly flow could support a few weakly organized cells/clusters capable of locally damaging wind. ...Parts of ND... A mid/upper-level shortwave trough is forecast to move across parts of SK/MB on Saturday, with some influence of this shortwave expected to extend into parts of ND. Isolated to widely scattered thunderstorm development will be possible during the afternoon/evening, with moderate buoyancy and sufficient deep-layer shear supporting potential for a few organized storms capable of isolated hail and strong/severe gusts. ..Dean.. 06/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN MO...CENTRAL/EASTERN IA...SOUTHEAST MN...CENTRAL/SOUTHERN WI...NORTHWEST IL... ...SUMMARY... Severe storms will be possible across the upper Mississippi Valley and upper Midwest on Saturday. Damaging wind, isolated hail, and a tornado or two are all possible. ...East-central Great Plains into the upper Midwest... The Slight Risk has been shifted southward, based on the latest guidance regarding the likely position of the primary surface boundary during the afternoon and evening. A convectively enhanced shortwave trough is forecast to move across the upper Midwest on Saturday. In the wake of morning convection, moderate to locally strong buoyancy is expected to develop from eastern KS/southeast NE northeastward into parts of southern WI/northern IL, along/south of an outflow-reinforced front. Scattered thunderstorms are expected to develop along the front by late afternoon and spread eastward into the evening. Effective shear generally in the 30-40 kt range will support a few organized cells/clusters. Relatively strong heating and large PW will support strong/damaging gusts as the most likely hazard. Warm temperatures aloft and weak midlevel lapse rates should limit the hail threat, though isolated hail cannot be ruled out if any supercells can be sustained. A tornado or two will also be possible, in the presence of moderate low-level southwesterly flow and modestly enhanced SRH. Farther east, intensification of morning convection and/or afternoon redevelopment will be possible across parts of lower MI. While instability will be weaker compared to areas father west, somewhat enhanced low/midlevel flow will support a threat for isolated damaging wind and possibly a brief tornado. ...Parts of the Northeast... Widely scattered thunderstorms will be possible across parts of the Northeast during the afternoon and evening, within a warm, moderately unstable, and weakly capped environment along/south of a cold front draped across parts of New England. Modest midlevel west-southwesterly flow could support a few weakly organized cells/clusters capable of locally damaging wind. ...Parts of ND... A mid/upper-level shortwave trough is forecast to move across parts of SK/MB on Saturday, with some influence of this shortwave expected to extend into parts of ND. Isolated to widely scattered thunderstorm development will be possible during the afternoon/evening, with moderate buoyancy and sufficient deep-layer shear supporting potential for a few organized storms capable of isolated hail and strong/severe gusts. ..Dean.. 06/21/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... For Saturday, upper-level ridging will gradually shift westward and the strongest mid-level winds will stay within the northern half of the CONUS. An upper-level shortwave will approach the Northwest late in the period. Surface winds will again be generally light across the Great Basin into the Northwest. While brief and locally elevated conditions may occur, highlights do not appear necessary at this time. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... For Saturday, upper-level ridging will gradually shift westward and the strongest mid-level winds will stay within the northern half of the CONUS. An upper-level shortwave will approach the Northwest late in the period. Surface winds will again be generally light across the Great Basin into the Northwest. While brief and locally elevated conditions may occur, highlights do not appear necessary at this time. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... For Saturday, upper-level ridging will gradually shift westward and the strongest mid-level winds will stay within the northern half of the CONUS. An upper-level shortwave will approach the Northwest late in the period. Surface winds will again be generally light across the Great Basin into the Northwest. While brief and locally elevated conditions may occur, highlights do not appear necessary at this time. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... For Saturday, upper-level ridging will gradually shift westward and the strongest mid-level winds will stay within the northern half of the CONUS. An upper-level shortwave will approach the Northwest late in the period. Surface winds will again be generally light across the Great Basin into the Northwest. While brief and locally elevated conditions may occur, highlights do not appear necessary at this time. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Though the upper-level trough across the West will be losing amplitude today, some mid-level flow enhancement will remain across the parts of the southern Great Basin. Mid-level moisture will also continue to push northwestward. Locally dry and breezy conditions appear probable in parts of western Arizona into southern Nevada and southwest Utah. Absent any stronger synoptic features, duration of any elevated conditions should be rather brief. Thunderstorms are likely across the Southwest into the Great Basin. This activity should produce wetting rains. Along the periphery of the moisture plume, some drier thunderstorms are possible. However, initiation and coverage in northern Nevada/southern Idaho are much too uncertain for any highlights. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Though the upper-level trough across the West will be losing amplitude today, some mid-level flow enhancement will remain across the parts of the southern Great Basin. Mid-level moisture will also continue to push northwestward. Locally dry and breezy conditions appear probable in parts of western Arizona into southern Nevada and southwest Utah. Absent any stronger synoptic features, duration of any elevated conditions should be rather brief. Thunderstorms are likely across the Southwest into the Great Basin. This activity should produce wetting rains. Along the periphery of the moisture plume, some drier thunderstorms are possible. However, initiation and coverage in northern Nevada/southern Idaho are much too uncertain for any highlights. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Though the upper-level trough across the West will be losing amplitude today, some mid-level flow enhancement will remain across the parts of the southern Great Basin. Mid-level moisture will also continue to push northwestward. Locally dry and breezy conditions appear probable in parts of western Arizona into southern Nevada and southwest Utah. Absent any stronger synoptic features, duration of any elevated conditions should be rather brief. Thunderstorms are likely across the Southwest into the Great Basin. This activity should produce wetting rains. Along the periphery of the moisture plume, some drier thunderstorms are possible. However, initiation and coverage in northern Nevada/southern Idaho are much too uncertain for any highlights. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Though the upper-level trough across the West will be losing amplitude today, some mid-level flow enhancement will remain across the parts of the southern Great Basin. Mid-level moisture will also continue to push northwestward. Locally dry and breezy conditions appear probable in parts of western Arizona into southern Nevada and southwest Utah. Absent any stronger synoptic features, duration of any elevated conditions should be rather brief. Thunderstorms are likely across the Southwest into the Great Basin. This activity should produce wetting rains. Along the periphery of the moisture plume, some drier thunderstorms are possible. However, initiation and coverage in northern Nevada/southern Idaho are much too uncertain for any highlights. ..Wendt.. 06/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY AND OVER THE FOUR CORNERS REGION... ...SUMMARY... Scattered strong to severe storms are expected from parts of the northern High Plains into the upper Mississippi Valley on Friday. Scattered strong/severe thunderstorms are also possible in the Four Corners vicinity. A few strong storms may also be noted into parts of the lower Great Lakes to southern New England. ...Northern High Plains to the upper Mississippi Valley... Latest water-vapor imagery depicts a low-amplitude short-wave trough over eastern WA/OR. This feature is forecast to shift into the northern Rockies later today. Surface high pressure over MB/SK/Dakotas will ensure southeasterly low-level flow deep into MT ahead of the short wave. 40kt 500mb flow will develop across central MT as the ridge flattens and scattered robust convection should easily develop within a flow regime favorable for supercells. Forecast sounding for central MT exhibit favorable deep-layer shear with strong buoyancy and relatively low cloud bases. Scattered supercells should evolve by early afternoon then propagate southeast along the instability axis toward south-central MT by early evening. Very large hail, gusty winds, and even a few tornadoes can be expected. Downstream across the upper MS Valley, low-level warm advection will focus along a frontal zone that is expected to be draped across WI/southern MN into southeast SD. Latest model guidance suggests a weak short-wave trough will approach eastern SD/MN border by 22/00z. This feature should encourage some increase in the LLJ across IA into southern MN. Strong diurnal heating south of the boundary will ease CINH across the warm sector and scattered storms are expected to develop. Updrafts may initially develop along the cool side of the boundary but with time surface-based updrafts are expected. Hail, wind, and perhaps a few tornadoes can be expected with supercells near the front. ...Four Corners region... Remnants of TS Alberta are progressing west across Mexico as upper ridging builds west into the middle of the CONUS. This flow regime is creating favorable trajectories across the southwestern US for seasonally high PW plume to advance into the Four Corners region. Weak low-latitude short-wave trough over southern CA will eject across the Great Basin which will strengthen mid-level flow across southern UT into southwestern CO. Scattered supercells should develop along the southern fringe of this short wave where strong shear will support organized longer-lived updrafts. Large hail is the primary risk but some tornado risk does exist with this activity. ...Lower Great Lakes to southern New England... Strong boundary-layer heating will once again be noted across the lower Great Lakes region into portions of southern New England. It appears a zone of low-level confluence will extend across the upper OH Valley into southern New England which should help focus scattered convection by peak heating. Gusty winds will be the primary concern with the most robust updrafts. ..Darrow/Wendt.. 06/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY AND OVER THE FOUR CORNERS REGION... ...SUMMARY... Scattered strong to severe storms are expected from parts of the northern High Plains into the upper Mississippi Valley on Friday. Scattered strong/severe thunderstorms are also possible in the Four Corners vicinity. A few strong storms may also be noted into parts of the lower Great Lakes to southern New England. ...Northern High Plains to the upper Mississippi Valley... Latest water-vapor imagery depicts a low-amplitude short-wave trough over eastern WA/OR. This feature is forecast to shift into the northern Rockies later today. Surface high pressure over MB/SK/Dakotas will ensure southeasterly low-level flow deep into MT ahead of the short wave. 40kt 500mb flow will develop across central MT as the ridge flattens and scattered robust convection should easily develop within a flow regime favorable for supercells. Forecast sounding for central MT exhibit favorable deep-layer shear with strong buoyancy and relatively low cloud bases. Scattered supercells should evolve by early afternoon then propagate southeast along the instability axis toward south-central MT by early evening. Very large hail, gusty winds, and even a few tornadoes can be expected. Downstream across the upper MS Valley, low-level warm advection will focus along a frontal zone that is expected to be draped across WI/southern MN into southeast SD. Latest model guidance suggests a weak short-wave trough will approach eastern SD/MN border by 22/00z. This feature should encourage some increase in the LLJ across IA into southern MN. Strong diurnal heating south of the boundary will ease CINH across the warm sector and scattered storms are expected to develop. Updrafts may initially develop along the cool side of the boundary but with time surface-based updrafts are expected. Hail, wind, and perhaps a few tornadoes can be expected with supercells near the front. ...Four Corners region... Remnants of TS Alberta are progressing west across Mexico as upper ridging builds west into the middle of the CONUS. This flow regime is creating favorable trajectories across the southwestern US for seasonally high PW plume to advance into the Four Corners region. Weak low-latitude short-wave trough over southern CA will eject across the Great Basin which will strengthen mid-level flow across southern UT into southwestern CO. Scattered supercells should develop along the southern fringe of this short wave where strong shear will support organized longer-lived updrafts. Large hail is the primary risk but some tornado risk does exist with this activity. ...Lower Great Lakes to southern New England... Strong boundary-layer heating will once again be noted across the lower Great Lakes region into portions of southern New England. It appears a zone of low-level confluence will extend across the upper OH Valley into southern New England which should help focus scattered convection by peak heating. Gusty winds will be the primary concern with the most robust updrafts. ..Darrow/Wendt.. 06/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY AND OVER THE FOUR CORNERS REGION... ...SUMMARY... Scattered strong to severe storms are expected from parts of the northern High Plains into the upper Mississippi Valley on Friday. Scattered strong/severe thunderstorms are also possible in the Four Corners vicinity. A few strong storms may also be noted into parts of the lower Great Lakes to southern New England. ...Northern High Plains to the upper Mississippi Valley... Latest water-vapor imagery depicts a low-amplitude short-wave trough over eastern WA/OR. This feature is forecast to shift into the northern Rockies later today. Surface high pressure over MB/SK/Dakotas will ensure southeasterly low-level flow deep into MT ahead of the short wave. 40kt 500mb flow will develop across central MT as the ridge flattens and scattered robust convection should easily develop within a flow regime favorable for supercells. Forecast sounding for central MT exhibit favorable deep-layer shear with strong buoyancy and relatively low cloud bases. Scattered supercells should evolve by early afternoon then propagate southeast along the instability axis toward south-central MT by early evening. Very large hail, gusty winds, and even a few tornadoes can be expected. Downstream across the upper MS Valley, low-level warm advection will focus along a frontal zone that is expected to be draped across WI/southern MN into southeast SD. Latest model guidance suggests a weak short-wave trough will approach eastern SD/MN border by 22/00z. This feature should encourage some increase in the LLJ across IA into southern MN. Strong diurnal heating south of the boundary will ease CINH across the warm sector and scattered storms are expected to develop. Updrafts may initially develop along the cool side of the boundary but with time surface-based updrafts are expected. Hail, wind, and perhaps a few tornadoes can be expected with supercells near the front. ...Four Corners region... Remnants of TS Alberta are progressing west across Mexico as upper ridging builds west into the middle of the CONUS. This flow regime is creating favorable trajectories across the southwestern US for seasonally high PW plume to advance into the Four Corners region. Weak low-latitude short-wave trough over southern CA will eject across the Great Basin which will strengthen mid-level flow across southern UT into southwestern CO. Scattered supercells should develop along the southern fringe of this short wave where strong shear will support organized longer-lived updrafts. Large hail is the primary risk but some tornado risk does exist with this activity. ...Lower Great Lakes to southern New England... Strong boundary-layer heating will once again be noted across the lower Great Lakes region into portions of southern New England. It appears a zone of low-level confluence will extend across the upper OH Valley into southern New England which should help focus scattered convection by peak heating. Gusty winds will be the primary concern with the most robust updrafts. ..Darrow/Wendt.. 06/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Fri Jun 21 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY AND OVER THE FOUR CORNERS REGION... ...SUMMARY... Scattered strong to severe storms are expected from parts of the northern High Plains into the upper Mississippi Valley on Friday. Scattered strong/severe thunderstorms are also possible in the Four Corners vicinity. A few strong storms may also be noted into parts of the lower Great Lakes to southern New England. ...Northern High Plains to the upper Mississippi Valley... Latest water-vapor imagery depicts a low-amplitude short-wave trough over eastern WA/OR. This feature is forecast to shift into the northern Rockies later today. Surface high pressure over MB/SK/Dakotas will ensure southeasterly low-level flow deep into MT ahead of the short wave. 40kt 500mb flow will develop across central MT as the ridge flattens and scattered robust convection should easily develop within a flow regime favorable for supercells. Forecast sounding for central MT exhibit favorable deep-layer shear with strong buoyancy and relatively low cloud bases. Scattered supercells should evolve by early afternoon then propagate southeast along the instability axis toward south-central MT by early evening. Very large hail, gusty winds, and even a few tornadoes can be expected. Downstream across the upper MS Valley, low-level warm advection will focus along a frontal zone that is expected to be draped across WI/southern MN into southeast SD. Latest model guidance suggests a weak short-wave trough will approach eastern SD/MN border by 22/00z. This feature should encourage some increase in the LLJ across IA into southern MN. Strong diurnal heating south of the boundary will ease CINH across the warm sector and scattered storms are expected to develop. Updrafts may initially develop along the cool side of the boundary but with time surface-based updrafts are expected. Hail, wind, and perhaps a few tornadoes can be expected with supercells near the front. ...Four Corners region... Remnants of TS Alberta are progressing west across Mexico as upper ridging builds west into the middle of the CONUS. This flow regime is creating favorable trajectories across the southwestern US for seasonally high PW plume to advance into the Four Corners region. Weak low-latitude short-wave trough over southern CA will eject across the Great Basin which will strengthen mid-level flow across southern UT into southwestern CO. Scattered supercells should develop along the southern fringe of this short wave where strong shear will support organized longer-lived updrafts. Large hail is the primary risk but some tornado risk does exist with this activity. ...Lower Great Lakes to southern New England... Strong boundary-layer heating will once again be noted across the lower Great Lakes region into portions of southern New England. It appears a zone of low-level confluence will extend across the upper OH Valley into southern New England which should help focus scattered convection by peak heating. Gusty winds will be the primary concern with the most robust updrafts. ..Darrow/Wendt.. 06/21/2024 Read more

MD 1351 CONCERNING SEVERE THUNDERSTORM WATCH 440... FOR NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA
Mesoscale Discussion 1351 NWS Storm Prediction Center Norman OK 1137 PM CDT Thu Jun 20 2024 Areas affected...northeastern Nebraska...southeastern South Dakota Concerning...Severe Thunderstorm Watch 440... Valid 210437Z - 210600Z The severe weather threat for Severe Thunderstorm Watch 440 continues. SUMMARY...While thunderstorm development is likely to continue across the region overnight, the risk for severe weather is expected to remain limited and a new severe weather watch is not currently anticipated. DISCUSSION...With the approach of the weakening upstream cluster of storms and associated cold pool, the persistent, quasi-stationary supercell near O'Neill has finally accelerated northward and weakened to the north of the surface warm front. Stronger lingering convection within the cluster has been aided by lift along the leading edge of the eastward advancing cold pool, near where it intersects the warm front. However, it appears that this activity will weaken further as it progresses eastward, with renewed convective development possible in its wake, as the nose of a 30-40 kt southerly 850 mb jet remains focused near the O'Neill vicinity. In the presence of modest shear, the newer convective development may grow upscale and organize above the trailing convective outflow overnight. However, with updraft inflow likely to be characterized by rather modest to weak instability, the risk for convection to produce severe hail and wind seems likely to remain low. ..Kerr.. 06/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FSD...OAX...LBF... LAT...LON 43309900 43719740 43479615 42419614 42389724 42179877 42539883 42939888 43309900 Read more

WW 0440 Status Updates
STATUS REPORT ON WW 440 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 5 S BUB TO 45 SE 9V9. REMAINING VALID PORTION OF WW 440 MAY BE ALLOWED TO EXPIRE AT 21/05Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1351. ..KERR..06/21/24 ATTN...WFO...LBF...UNR...FSD... STATUS REPORT FOR WS 440 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC015-071-089-183-210500- NE . NEBRASKA COUNTIES INCLUDED ARE BOYD GARFIELD HOLT WHEELER SDC023-043-210500- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CHARLES MIX DOUGLAS THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 440 SEVERE TSTM NE SD 202155Z - 210500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 440 NWS Storm Prediction Center Norman OK 455 PM CDT Thu Jun 20 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northern Nebraska Extreme southern South Dakota * Effective this Thursday afternoon from 455 PM until Midnight CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 3.5 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...An isolated supercell should persist along a warm front over the northern Sandhills, offering all severe hazards, including a localized tornado threat. In the broader picture, a clustering of severe thunderstorms in the Nebraska Panhandle should move into and across the watch later this evening, posing mainly a hail and severe-wind threat. Isolate severe hail also is possible with later development north of the front. The severe thunderstorm watch area is approximately along and 55 statute miles north and south of a line from 50 miles west of Mullen NE to 15 miles east northeast of Oneill NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 438...WW 439... AVIATION...A few severe thunderstorms with hail surface and aloft to 3.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 26025. ...Edwards Read more

WW 0440 Status Updates
STATUS REPORT ON WW 440 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NW BBW TO 30 ESE ANW TO 40 SSW 9V9. ..KERR..06/21/24 ATTN...WFO...LBF...UNR...FSD... STATUS REPORT FOR WS 440 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC015-071-089-103-115-149-183-210440- NE . NEBRASKA COUNTIES INCLUDED ARE BOYD GARFIELD HOLT KEYA PAHA LOUP ROCK WHEELER SDC023-043-053-210440- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE CHARLES MIX DOUGLAS GREGORY THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more