Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN DAKOTAS INTO NORTHWESTERN MINNESOTA... ...SUMMARY... Scattered severe storms may develop across the northern Plains area on Sunday, with more isolated severe potential southwestward into the southern Rockies on Sunday. A couple of strong/marginally severe storms may also occur across the Lower Great Lakes/Upper Ohio Valley vicinity. ...Synopsis... A progressing western U.S. upper trough is forecast to gradually weaken, as it impinges on a persistent central U.S. ridge. The result will be that the trough gets shunted northeastward toward Montana/Wyoming with time. Meanwhile, weak upper troughing will persist over the Northeast. At the surface, a cold front will progress eastward across the Canadian Prairie, and the north-central U.S. with time. By the end of the period, the front should stretch from Minnesota southwestward to northeastern Colorado. ...Northern Plains southwestward to the Four Corners region... As the western U.S. trough advances eastward, large-scale ascent will support scattered thunderstorm development across the Intermountain Region, within a diurnally destabilizing airmass. While CAPE will remain limited, moderate southwesterly flow aloft ahead of the trough will allow some storm organization/longevity at time. This, combined with a deep mixed layer providing support for enhanced downdrafts with the stronger cells, will result in risk for locally severe wind gusts. More substantial severe risk could evolve across portions of the north-central states, where much greater instability will evolve. Though the airmass should remain capped in most areas, ascent may be sufficient to support local cap breaches by late afternoon to allow isolated storm development. If storms develop, upscale growth near convective outflows would be expected, possibly resulting in evening/overnight MCS development. Large hail would be possible with the initial storms, though with locally damaging gusts likely to be the dominant risk. Still, given the capping that is anticipated, and questions whether ascent will be sufficient to allow storm development, will maintain only conditional 15%/SLGT risk at this time. ...Lower Great Lakes/Upper Ohio Valley area... On the western fringe of the northeastern U.S. trough, moderate northwesterly flow aloft may combine with modest afternoon destabilization to support isolated storm development. Assuming this occurs, a few strong gusts would be possible as storms would move rather quickly southeastward. The main question remains the degree of destabilization which may occur, and thus will introduce only 5%/MRGL risk at this time. ..Goss.. 08/24/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN DAKOTAS INTO NORTHWESTERN MINNESOTA... ...SUMMARY... Scattered severe storms may develop across the northern Plains area on Sunday, with more isolated severe potential southwestward into the southern Rockies on Sunday. A couple of strong/marginally severe storms may also occur across the Lower Great Lakes/Upper Ohio Valley vicinity. ...Synopsis... A progressing western U.S. upper trough is forecast to gradually weaken, as it impinges on a persistent central U.S. ridge. The result will be that the trough gets shunted northeastward toward Montana/Wyoming with time. Meanwhile, weak upper troughing will persist over the Northeast. At the surface, a cold front will progress eastward across the Canadian Prairie, and the north-central U.S. with time. By the end of the period, the front should stretch from Minnesota southwestward to northeastern Colorado. ...Northern Plains southwestward to the Four Corners region... As the western U.S. trough advances eastward, large-scale ascent will support scattered thunderstorm development across the Intermountain Region, within a diurnally destabilizing airmass. While CAPE will remain limited, moderate southwesterly flow aloft ahead of the trough will allow some storm organization/longevity at time. This, combined with a deep mixed layer providing support for enhanced downdrafts with the stronger cells, will result in risk for locally severe wind gusts. More substantial severe risk could evolve across portions of the north-central states, where much greater instability will evolve. Though the airmass should remain capped in most areas, ascent may be sufficient to support local cap breaches by late afternoon to allow isolated storm development. If storms develop, upscale growth near convective outflows would be expected, possibly resulting in evening/overnight MCS development. Large hail would be possible with the initial storms, though with locally damaging gusts likely to be the dominant risk. Still, given the capping that is anticipated, and questions whether ascent will be sufficient to allow storm development, will maintain only conditional 15%/SLGT risk at this time. ...Lower Great Lakes/Upper Ohio Valley area... On the western fringe of the northeastern U.S. trough, moderate northwesterly flow aloft may combine with modest afternoon destabilization to support isolated storm development. Assuming this occurs, a few strong gusts would be possible as storms would move rather quickly southeastward. The main question remains the degree of destabilization which may occur, and thus will introduce only 5%/MRGL risk at this time. ..Goss.. 08/24/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN DAKOTAS INTO NORTHWESTERN MINNESOTA... ...SUMMARY... Scattered severe storms may develop across the northern Plains area on Sunday, with more isolated severe potential southwestward into the southern Rockies on Sunday. A couple of strong/marginally severe storms may also occur across the Lower Great Lakes/Upper Ohio Valley vicinity. ...Synopsis... A progressing western U.S. upper trough is forecast to gradually weaken, as it impinges on a persistent central U.S. ridge. The result will be that the trough gets shunted northeastward toward Montana/Wyoming with time. Meanwhile, weak upper troughing will persist over the Northeast. At the surface, a cold front will progress eastward across the Canadian Prairie, and the north-central U.S. with time. By the end of the period, the front should stretch from Minnesota southwestward to northeastern Colorado. ...Northern Plains southwestward to the Four Corners region... As the western U.S. trough advances eastward, large-scale ascent will support scattered thunderstorm development across the Intermountain Region, within a diurnally destabilizing airmass. While CAPE will remain limited, moderate southwesterly flow aloft ahead of the trough will allow some storm organization/longevity at time. This, combined with a deep mixed layer providing support for enhanced downdrafts with the stronger cells, will result in risk for locally severe wind gusts. More substantial severe risk could evolve across portions of the north-central states, where much greater instability will evolve. Though the airmass should remain capped in most areas, ascent may be sufficient to support local cap breaches by late afternoon to allow isolated storm development. If storms develop, upscale growth near convective outflows would be expected, possibly resulting in evening/overnight MCS development. Large hail would be possible with the initial storms, though with locally damaging gusts likely to be the dominant risk. Still, given the capping that is anticipated, and questions whether ascent will be sufficient to allow storm development, will maintain only conditional 15%/SLGT risk at this time. ...Lower Great Lakes/Upper Ohio Valley area... On the western fringe of the northeastern U.S. trough, moderate northwesterly flow aloft may combine with modest afternoon destabilization to support isolated storm development. Assuming this occurs, a few strong gusts would be possible as storms would move rather quickly southeastward. The main question remains the degree of destabilization which may occur, and thus will introduce only 5%/MRGL risk at this time. ..Goss.. 08/24/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Fri Aug 23 2024 Valid 240100Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A SMALL PART OF NORTHWEST/NORTH-CENTRAL MT... ...SUMMARY... A threat for severe gusts will continue across parts of Montana through mid evening. Other strong to severe storms remain possible across eastern Utah and western Colorado, and also across the central High Plains. ...Montana... Scattered thunderstorms with a history of producing measured severe gusts are quickly moving northward across northwest MT early this evening, and will soon move across the international border. Farther east, a storm cluster across central MT may continue to pose a threat of severe gusts as it moves through a relatively warm and well-mixed environment. A separate cluster of storms across northeast MT may continue to pose a short-term threat of isolated hail and severe gusts, before increasing MLCINH reduces convective potential later tonight. ...Central High Plains into western MO... A small outflow-driven cluster of storms is moving across parts of the central High Plains early this evening. A short-term threat for isolated severe gusts and hail may spread eastward through mid evening, as the cluster moves through a moderately unstable and marginally sheared environment. Increasing MLCINH with time may eventually result in a weakening trend, though stronger elevated convection may persist through the night as the remnant cluster moves eastward. Some increase in elevated storms will also be possible near the end of the period across western MO, within a low-level warm-advection regime. Moderate MUCAPE could support a few stronger storms with small hail and gusty winds, but severe potential prior to 12Z within this regime appears relatively limited. ...Eastern UT into western CO... A couple stronger storms may persist through at least part of the evening from eastern UT into western CO, where MLCAPE in excess of 500 J/kg and favorable deep-layer shear may support transient supercell structures capable of isolated hail and strong/severe gusts. ..Dean.. 08/24/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Fri Aug 23 2024 Valid 240100Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A SMALL PART OF NORTHWEST/NORTH-CENTRAL MT... ...SUMMARY... A threat for severe gusts will continue across parts of Montana through mid evening. Other strong to severe storms remain possible across eastern Utah and western Colorado, and also across the central High Plains. ...Montana... Scattered thunderstorms with a history of producing measured severe gusts are quickly moving northward across northwest MT early this evening, and will soon move across the international border. Farther east, a storm cluster across central MT may continue to pose a threat of severe gusts as it moves through a relatively warm and well-mixed environment. A separate cluster of storms across northeast MT may continue to pose a short-term threat of isolated hail and severe gusts, before increasing MLCINH reduces convective potential later tonight. ...Central High Plains into western MO... A small outflow-driven cluster of storms is moving across parts of the central High Plains early this evening. A short-term threat for isolated severe gusts and hail may spread eastward through mid evening, as the cluster moves through a moderately unstable and marginally sheared environment. Increasing MLCINH with time may eventually result in a weakening trend, though stronger elevated convection may persist through the night as the remnant cluster moves eastward. Some increase in elevated storms will also be possible near the end of the period across western MO, within a low-level warm-advection regime. Moderate MUCAPE could support a few stronger storms with small hail and gusty winds, but severe potential prior to 12Z within this regime appears relatively limited. ...Eastern UT into western CO... A couple stronger storms may persist through at least part of the evening from eastern UT into western CO, where MLCAPE in excess of 500 J/kg and favorable deep-layer shear may support transient supercell structures capable of isolated hail and strong/severe gusts. ..Dean.. 08/24/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 PM CDT Fri Aug 23 2024 Valid 240100Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A SMALL PART OF NORTHWEST/NORTH-CENTRAL MT... ...SUMMARY... A threat for severe gusts will continue across parts of Montana through mid evening. Other strong to severe storms remain possible across eastern Utah and western Colorado, and also across the central High Plains. ...Montana... Scattered thunderstorms with a history of producing measured severe gusts are quickly moving northward across northwest MT early this evening, and will soon move across the international border. Farther east, a storm cluster across central MT may continue to pose a threat of severe gusts as it moves through a relatively warm and well-mixed environment. A separate cluster of storms across northeast MT may continue to pose a short-term threat of isolated hail and severe gusts, before increasing MLCINH reduces convective potential later tonight. ...Central High Plains into western MO... A small outflow-driven cluster of storms is moving across parts of the central High Plains early this evening. A short-term threat for isolated severe gusts and hail may spread eastward through mid evening, as the cluster moves through a moderately unstable and marginally sheared environment. Increasing MLCINH with time may eventually result in a weakening trend, though stronger elevated convection may persist through the night as the remnant cluster moves eastward. Some increase in elevated storms will also be possible near the end of the period across western MO, within a low-level warm-advection regime. Moderate MUCAPE could support a few stronger storms with small hail and gusty winds, but severe potential prior to 12Z within this regime appears relatively limited. ...Eastern UT into western CO... A couple stronger storms may persist through at least part of the evening from eastern UT into western CO, where MLCAPE in excess of 500 J/kg and favorable deep-layer shear may support transient supercell structures capable of isolated hail and strong/severe gusts. ..Dean.. 08/24/2024 Read more

MD 1983 CONCERNING SEVERE THUNDERSTORM WATCH 645... FOR WESTERN MONTANA
Mesoscale Discussion 1983 NWS Storm Prediction Center Norman OK 0604 PM CDT Fri Aug 23 2024 Areas affected...Western Montana Concerning...Severe Thunderstorm Watch 645... Valid 232304Z - 240100Z The severe weather threat for Severe Thunderstorm Watch 645 continues. SUMMARY...Severe wind gust potential continues with convection this evening. DISCUSSION...Satellite imagery depicts a well-defined short-wave trough, extending from northeast OR-ID-extreme western WY, lifting north across the northern Rockies. Large-scale height falls are noted ahead of this feature as 500mb flow on the order of 50kt translates across the Bitter Roots into western MT. An arcing corridor of scattered robust convection has developed ahead of the short wave, and while this activity is developing within a weak-instability airmass, severe gusts have been common. Over the next few hours it appears the primary area of concern will extend across northern portions of ww645 where instability has yet to be overturned. ..Darrow.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...RIW...TFX...PIH...MSO... LAT...LON 44641447 48961445 48961029 44651061 44641447 Read more

MD 1981 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN MONTANA
Mesoscale Discussion 1981 NWS Storm Prediction Center Norman OK 0539 PM CDT Fri Aug 23 2024 Areas affected...Eastern Montana Concerning...Severe potential...Watch unlikely Valid 232239Z - 240045Z Probability of Watch Issuance...20 percent SUMMARY...Isolated threat for wind/hail will be noted with convection this evening. Watch is not currently anticipated. DISCUSSION...Mid-level heights are being suppressed a bit over central/eastern MT along the eastern influence of a short-wave trough that is ejecting north across the northern Rockies. While large-scale influence of this feature will likely remain focused across western MT, strong boundary-layer heating has contributed to steep 0-3km lapse rates as temperature are now well into the mid 90s. Convective temperature have been breached, and negligible CINH is supported by thickening boundary-layer cu field, and isolated thunderstorms between GGW-OLF. This clustering is occurring within a zone of favorable low-level confluence, and along an instability axis where MLCAPE values are in excess of 2000 J/kg. There is some concern a few robust updrafts will evolve across eastern MT over the next few hours as surface-6km bulk shear is more than adequate for sustaining organized updrafts; however, it's not entirely clear how many storms will evolve. Another concern is any storms that linger beyond sunset will eventually be aided by a strengthening LLJ. Will continue to monitor this region, but at this time a watch is not currently anticipated. ..Darrow/Gleason.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW... LAT...LON 49010432 46200421 46210675 48800743 49010432 Read more

WW 0645 Status Updates
STATUS REPORT ON WW 645 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NNW LVM TO 25 SSW GTF TO 45 SSW CTB TO 40 SE GPI TO 35 SSW GPI. ..SPC..08/24/24 ATTN...WFO...TFX...MSO... STATUS REPORT FOR WS 645 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MTC005-013-015-027-029-035-041-045-051-053-059-073-099-101- 240140- MT . MONTANA COUNTIES INCLUDED ARE BLAINE CASCADE CHOUTEAU FERGUS FLATHEAD GLACIER HILL JUDITH BASIN LIBERTY LINCOLN MEAGHER PONDERA TETON TOOLE 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 0645 Status Updates
STATUS REPORT ON WW 645 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NNW LVM TO 25 SSW GTF TO 45 SSW CTB TO 40 SE GPI TO 35 SSW GPI. ..SPC..08/24/24 ATTN...WFO...TFX...MSO... STATUS REPORT FOR WS 645 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MTC005-013-015-027-029-035-041-045-051-053-059-073-099-101- 240140- MT . MONTANA COUNTIES INCLUDED ARE BLAINE CASCADE CHOUTEAU FERGUS FLATHEAD GLACIER HILL JUDITH BASIN LIBERTY LINCOLN MEAGHER PONDERA TETON TOOLE 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 645 SEVERE TSTM MT 232055Z - 240300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 645 NWS Storm Prediction Center Norman OK 255 PM MDT Fri Aug 23 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western and Central Montana * Effective this Friday afternoon and evening from 255 PM until 900 PM MDT. * Primary threats include... Isolated significant damaging wind gusts to 75 mph possible SUMMARY...Scattered thunderstorms will continue to develop and move north-northeastward across the region through early evening, with severe-caliber wind gusts a possibility. The severe thunderstorm watch area is approximately along and 95 statute miles east and west of a line from 25 miles north of Cut Bank MT to 40 miles south of Dillon MT. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 20030. ...Guyer Read more

MD 1982 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHEAST COLORADO...FAR SOUTHEAST WYOMING...AND WESTERN NEBRASKA
Mesoscale Discussion 1982 NWS Storm Prediction Center Norman OK 0553 PM CDT Fri Aug 23 2024 Areas affected...Portions of northeast Colorado...far southeast Wyoming...and western Nebraska Concerning...Severe potential...Watch unlikely Valid 232253Z - 240030Z Probability of Watch Issuance...20 percent SUMMARY...Storms may consolidate into a small cluster, posing a some threat for a few damaging wind gusts. Watch issuance not anticipated at this time, though convective trends will be monitored. DISCUSSION...Convection initiating off the high terrain areas of north-central Colorado and southeastern Wyoming has drifted eastward amid marginally enhanced westerly mid-level flow. This activity is increasing in intensity as it encounters richer low-level moisture, characterized by surface dew point temperatures in the low to mid 60s F within easterly upslope flow and greater instability (MLCAPE approaching 2000 J/kg) amid increasing surface temperatures. Storm intensity is expected to continue increasing in the short term as the activity moves into more favorable airmass. The combination of speed/directional shear is yielding effective bulk shear near 35 kt across the region, which may help to promote at least transient storm organization. Recent HRRR runs suggest a cluster may emerge over the next hour or so, which could pose at least a brief damaging wind/hail threat over northeast Colorado and the Nebraska Panhandle in the short term. However, increasing convective inhibition into the evening is expected limit the eastward extent of the severe threat, as supported by recent HRRR runs. For now, watch issuance is unlikely but convective trends will be monitored. ..Karstens/Gleason.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...BOU...CYS... LAT...LON 39560340 39600417 40760458 42660391 42780226 41510116 40310139 39500263 39560340 Read more

MD 1983 CONCERNING SEVERE THUNDERSTORM WATCH 645... FOR WESTERN MONTANA
Mesoscale Discussion 1983 NWS Storm Prediction Center Norman OK 0604 PM CDT Fri Aug 23 2024 Areas affected...Western Montana Concerning...Severe Thunderstorm Watch 645... Valid 232304Z - 240100Z The severe weather threat for Severe Thunderstorm Watch 645 continues. SUMMARY...Severe wind gust potential continues with convection this evening. DISCUSSION...Satellite imagery depicts a well-defined short-wave trough, extending from northeast OR-ID-extreme western WY, lifting north across the northern Rockies. Large-scale height falls are noted ahead of this feature as 500mb flow on the order of 50kt translates across the Bitter Roots into western MT. An arcing corridor of scattered robust convection has developed ahead of the short wave, and while this activity is developing within a weak-instability airmass, severe gusts have been common. Over the next few hours it appears the primary area of concern will extend across northern portions of ww645 where instability has yet to be overturned. ..Darrow.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...RIW...TFX...PIH...MSO... LAT...LON 44641447 48961445 48961029 44651061 44641447 Read more

MD 1982 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHEAST COLORADO...FAR SOUTHEAST WYOMING...AND WESTERN NEBRASKA
Mesoscale Discussion 1982 NWS Storm Prediction Center Norman OK 0553 PM CDT Fri Aug 23 2024 Areas affected...Portions of northeast Colorado...far southeast Wyoming...and western Nebraska Concerning...Severe potential...Watch unlikely Valid 232253Z - 240030Z Probability of Watch Issuance...20 percent SUMMARY...Storms may consolidate into a small cluster, posing a some threat for a few damaging wind gusts. Watch issuance not anticipated at this time, though convective trends will be monitored. DISCUSSION...Convection initiating off the high terrain areas of north-central Colorado and southeastern Wyoming has drifted eastward amid marginally enhanced westerly mid-level flow. This activity is increasing in intensity as it encounters richer low-level moisture, characterized by surface dew point temperatures in the low to mid 60s F within easterly upslope flow and greater instability (MLCAPE approaching 2000 J/kg) amid increasing surface temperatures. Storm intensity is expected to continue increasing in the short term as the activity moves into more favorable airmass. The combination of speed/directional shear is yielding effective bulk shear near 35 kt across the region, which may help to promote at least transient storm organization. Recent HRRR runs suggest a cluster may emerge over the next hour or so, which could pose at least a brief damaging wind/hail threat over northeast Colorado and the Nebraska Panhandle in the short term. However, increasing convective inhibition into the evening is expected limit the eastward extent of the severe threat, as supported by recent HRRR runs. For now, watch issuance is unlikely but convective trends will be monitored. ..Karstens/Gleason.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...BOU...CYS... LAT...LON 39560340 39600417 40760458 42660391 42780226 41510116 40310139 39500263 39560340 Read more

MD 1981 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN MONTANA
Mesoscale Discussion 1981 NWS Storm Prediction Center Norman OK 0539 PM CDT Fri Aug 23 2024 Areas affected...Eastern Montana Concerning...Severe potential...Watch unlikely Valid 232239Z - 240045Z Probability of Watch Issuance...20 percent SUMMARY...Isolated threat for wind/hail will be noted with convection this evening. Watch is not currently anticipated. DISCUSSION...Mid-level heights are being suppressed a bit over central/eastern MT along the eastern influence of a short-wave trough that is ejecting north across the northern Rockies. While large-scale influence of this feature will likely remain focused across western MT, strong boundary-layer heating has contributed to steep 0-3km lapse rates as temperature are now well into the mid 90s. Convective temperature have been breached, and negligible CINH is supported by thickening boundary-layer cu field, and isolated thunderstorms between GGW-OLF. This clustering is occurring within a zone of favorable low-level confluence, and along an instability axis where MLCAPE values are in excess of 2000 J/kg. There is some concern a few robust updrafts will evolve across eastern MT over the next few hours as surface-6km bulk shear is more than adequate for sustaining organized updrafts; however, it's not entirely clear how many storms will evolve. Another concern is any storms that linger beyond sunset will eventually be aided by a strengthening LLJ. Will continue to monitor this region, but at this time a watch is not currently anticipated. ..Darrow/Gleason.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW... LAT...LON 49010432 46200421 46210675 48800743 49010432 Read more

MD 1980 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN KANSAS...FAR EASTERN COLORADO...THE OK/TX PANHANDLES AND NORTHWEST OKLAHOMA
Mesoscale Discussion 1980 NWS Storm Prediction Center Norman OK 0515 PM CDT Fri Aug 23 2024 Areas affected...Western Kansas...far Eastern Colorado...the OK/TX Panhandles and Northwest Oklahoma Concerning...Severe potential...Watch unlikely Valid 232215Z - 232345Z Probability of Watch Issuance...5 percent SUMMARY...A few damaging wind gusts and severe hail possible with the strongest cells into the evening. DISCUSSION...Visible satellite shows an uptick in convective development across the region as peak heating has allowed surface temperatures to rise into the upper 90s and low 100s F, eclipsing convective temperatures. Southeasterly low-level flow has ushered in ample moisture, with surface dew point temperatures in the mid 60s F. This combination is yielding MLCAPE of 1500-2000 J/kg in areas downstream of northeastward-moving developing convection. Marginally enhanced west-southwesterly mid-level flow is resulting in upwards of 30-35 kt of effective bulk shear that increases with northward extent. The ongoing convective activity is expected to continue through the evening. Steep low-level lapse rates should promote a few damaging wind gusts with the strongest cells, along with some severe hail. However, convective inhibition increases with eastward extent. This along with a gradual loss of peak heating should limit storm organization and severe coverage, though convective trends will be monitored. ..Karstens/Gleason.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OUN...DDC...GLD...AMA...PUB... LAT...LON 37850262 38460262 39060157 38740052 38059986 37289892 36619843 35889873 36140010 36860156 37850262 Read more

MD 1979 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHERN/EASTERN UTAH INTO FAR WESTERN COLORADO
Mesoscale Discussion 1979 NWS Storm Prediction Center Norman OK 0353 PM CDT Fri Aug 23 2024 Areas affected...Portions of southern/eastern Utah into far western Colorado Concerning...Severe potential...Watch unlikely Valid 232053Z - 232300Z Probability of Watch Issuance...20 percent SUMMARY...Scattered storms, some capable of severe winds and large hail, will occur this afternoon. A watch is not currently anticipated. DISCUSSION...Early cloud cover within the Colorado Plateau has kept temperatures in the mid/upper 70s F thus far. Even so, colder air aloft has promoted around 1000 J/kg MLCAPE in southeastern Utah. Convection has shown signs of deepening on MRMS CAPPI imagery. Some further intensification of this activity is possible as temperatures will still rise this afternoon. Moderate mid-level flow on the eastern flank of the upper low will foster 45-50 kts of effective shear and at least marginal supercell structures. Storms will be capable of severe wind gusts and possibly large hail. ..Wendt/Guyer.. 08/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GJT...FGZ...SLC... LAT...LON 37461224 38391155 39331063 39590951 39220889 38200878 37400900 36991014 36741130 36771203 36981233 37461224 Read more

WW 0645 Status Updates
STATUS REPORT ON WW 645 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..SPC..08/23/24 ATTN...WFO...TFX...MSO... STATUS REPORT FOR WS 645 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MTC001-005-007-013-015-023-027-029-031-035-039-041-043-045-047- 049-051-053-057-059-061-063-073-077-081-089-093-099-101- 232340- MT . MONTANA COUNTIES INCLUDED ARE BEAVERHEAD BLAINE BROADWATER CASCADE CHOUTEAU DEER LODGE FERGUS FLATHEAD GALLATIN GLACIER GRANITE HILL JEFFERSON JUDITH BASIN LAKE LEWIS AND CLARK LIBERTY LINCOLN MADISON MEAGHER MINERAL MISSOULA PONDERA POWELL RAVALLI SANDERS SILVER BOW TETON TOOLE 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