Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0747 AM CDT Tue Sep 17 2019 Valid 171300Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING ACROSS THE NORTHERN HIGH PLAINS...AND TONIGHT FOR MN AND VICINITY... ...SUMMARY... A few severe storms with damaging winds and large hail are expected across the northern high Plains area this afternoon/evening, and overnight across Minnesota and vicinity. ...Northern High Plains this afternoon/evening... A midlevel shortwave trough over the northern Great Basin will eject northeastward to ND tonight. Surface cyclogenesis is expected near the northwest ND/northeast MT/SK border by this evening, and this cyclone will move northeastward into southern MB overnight. Strong forcing for ascent will accompany the cyclone (within the left-exit region of the mid-upper jet), but lingering convective inhibition and only modest low-level moisture/buoyancy will tend to limit storm coverage/intensity. Still, there will be enough downdraft and momentum transfer potential to support at least isolated severe/damaging winds from eastern WY/western SD this afternoon into western ND this evening. ...MN area today into tonight... A cluster of thunderstorms is ongoing this morning across central MN, in a zone of focused low-level warm advection associated with a compact midlevel shortwave trough. This zone of ascent will spread northeastward toward the MN Arrowhead by early afternoon. Though the convection will be slightly elevated this morning, there will be some potential for a strong storm or two with hail by early afternoon along the southern flank of the convective cluster. There will be no clear focus for additional thunderstorm development this afternoon across MN, in the wake of the ejecting shortwave trough. East of the surface cold front moving across the Dakotas tonight, a low-level jet will strengthen to 50 kt from NE to MN. This will occur along the low-level moist axis, where moderate buoyancy will persist well into the overnight hours. A pre-frontal, mixed-mode band of slightly elevated storms is expected to form tonight near the SD/MN border and spread northeastward and eastward overnight. The increasing low-level flow and MUCAPE near 2000 J/kg will support a threat for at least isolated damaging winds and marginally severe hail. ...TX coastal plain through early Wednesday... A weak tropical low south of Matagorda will drift northward to the Fort Bend/western Harris County area by 12z Wednesday. There is some potential for strengthening with this system prior to moving inland, though wind fields are not expected to become strong enough to support a threat for supercells/tornadoes. Otherwise, training convection and very heavy rainfall will be the main concern. ..Thompson/Kerr.. 09/17/2019 Read more

No watches are valid as of Tue Sep 17 12:54:02 UTC 2019.

No Mesoscale Discussions are in effect as of Tue Sep 17 12:54:02 UTC 2019.

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0342 AM CDT Tue Sep 17 2019 Valid 201200Z - 251200Z ...DISCUSSION... A shortwave trough is forecast to move from the Great Basin or Four Corners area northeastward into the Northern Plains on Friday/D4, with a cold front progressing across the region. MUCAPE in excess of 2000 J/kg is likely ahead of the front, over the eastern Dakotas, northern NE and into western MN. Storms will become widespread during the day with little if any capping. Steep lapse rates aloft and increasing mean winds through a deep layer will support areas of damaging winds and hail, with mixed storm modes expected. For Saturday/D5, models suggest low predictability with the evolution of the northern Plains/Great Lakes trough, but severe storms cannot be ruled out on Saturday for parts of the region. An antecedent high over the East will likely mitigate storm potential as the upper trough continues into the Northeast during the D6-D8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0342 AM CDT Tue Sep 17 2019 Valid 201200Z - 251200Z ...DISCUSSION... A shortwave trough is forecast to move from the Great Basin or Four Corners area northeastward into the Northern Plains on Friday/D4, with a cold front progressing across the region. MUCAPE in excess of 2000 J/kg is likely ahead of the front, over the eastern Dakotas, northern NE and into western MN. Storms will become widespread during the day with little if any capping. Steep lapse rates aloft and increasing mean winds through a deep layer will support areas of damaging winds and hail, with mixed storm modes expected. For Saturday/D5, models suggest low predictability with the evolution of the northern Plains/Great Lakes trough, but severe storms cannot be ruled out on Saturday for parts of the region. An antecedent high over the East will likely mitigate storm potential as the upper trough continues into the Northeast during the D6-D8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0342 AM CDT Tue Sep 17 2019 Valid 201200Z - 251200Z ...DISCUSSION... A shortwave trough is forecast to move from the Great Basin or Four Corners area northeastward into the Northern Plains on Friday/D4, with a cold front progressing across the region. MUCAPE in excess of 2000 J/kg is likely ahead of the front, over the eastern Dakotas, northern NE and into western MN. Storms will become widespread during the day with little if any capping. Steep lapse rates aloft and increasing mean winds through a deep layer will support areas of damaging winds and hail, with mixed storm modes expected. For Saturday/D5, models suggest low predictability with the evolution of the northern Plains/Great Lakes trough, but severe storms cannot be ruled out on Saturday for parts of the region. An antecedent high over the East will likely mitigate storm potential as the upper trough continues into the Northeast during the D6-D8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0342 AM CDT Tue Sep 17 2019 Valid 201200Z - 251200Z ...DISCUSSION... A shortwave trough is forecast to move from the Great Basin or Four Corners area northeastward into the Northern Plains on Friday/D4, with a cold front progressing across the region. MUCAPE in excess of 2000 J/kg is likely ahead of the front, over the eastern Dakotas, northern NE and into western MN. Storms will become widespread during the day with little if any capping. Steep lapse rates aloft and increasing mean winds through a deep layer will support areas of damaging winds and hail, with mixed storm modes expected. For Saturday/D5, models suggest low predictability with the evolution of the northern Plains/Great Lakes trough, but severe storms cannot be ruled out on Saturday for parts of the region. An antecedent high over the East will likely mitigate storm potential as the upper trough continues into the Northeast during the D6-D8 period. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 AM CDT Tue Sep 17 2019 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS... ...SUMMARY... At least isolated storms producing large hail are possible Thursday evening and overnight over the northern High Plains. ...Synopsis... An upper trough will continue to slowly move east across the Great Basin and toward the Rockies with increasing south/southwest flow aloft into the northern High Plains. Meanwhile, an upper high will remain situated over the Southeast, with a surface high over the Mid Atlantic maintaining dry conditions there. Southerly winds over the Plains will maintain 65-70 F dewpoints from TX to MN, with a tropical disturbance possibly over eastern TX. The slow-moving western trough will also create lift over the northern High Plains as a cold front encounters an unstable air mass Thursday afternoon into Friday. ...Northern High Plains... Low pressure will develop over eastern WY during the afternoon with a wind shift over eastern MT. Southeast surface winds will maintain moist and unstable conditions over the Dakotas and Nebraska during the day, with continued northwestward warm advection during the evening with a 40-50 kt low-level jet. Steepening lapse rates aloft combined with sufficient deep-layer shear will support at least isolated severe storms capable of damaging hail. Locally damaging winds cannot be ruled out, although the majority of the storms are expected overnight. ..Jewell.. 09/17/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 AM CDT Tue Sep 17 2019 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS... ...SUMMARY... At least isolated storms producing large hail are possible Thursday evening and overnight over the northern High Plains. ...Synopsis... An upper trough will continue to slowly move east across the Great Basin and toward the Rockies with increasing south/southwest flow aloft into the northern High Plains. Meanwhile, an upper high will remain situated over the Southeast, with a surface high over the Mid Atlantic maintaining dry conditions there. Southerly winds over the Plains will maintain 65-70 F dewpoints from TX to MN, with a tropical disturbance possibly over eastern TX. The slow-moving western trough will also create lift over the northern High Plains as a cold front encounters an unstable air mass Thursday afternoon into Friday. ...Northern High Plains... Low pressure will develop over eastern WY during the afternoon with a wind shift over eastern MT. Southeast surface winds will maintain moist and unstable conditions over the Dakotas and Nebraska during the day, with continued northwestward warm advection during the evening with a 40-50 kt low-level jet. Steepening lapse rates aloft combined with sufficient deep-layer shear will support at least isolated severe storms capable of damaging hail. Locally damaging winds cannot be ruled out, although the majority of the storms are expected overnight. ..Jewell.. 09/17/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0220 AM CDT Tue Sep 17 2019 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS... ...SUMMARY... At least isolated storms producing large hail are possible Thursday evening and overnight over the northern High Plains. ...Synopsis... An upper trough will continue to slowly move east across the Great Basin and toward the Rockies with increasing south/southwest flow aloft into the northern High Plains. Meanwhile, an upper high will remain situated over the Southeast, with a surface high over the Mid Atlantic maintaining dry conditions there. Southerly winds over the Plains will maintain 65-70 F dewpoints from TX to MN, with a tropical disturbance possibly over eastern TX. The slow-moving western trough will also create lift over the northern High Plains as a cold front encounters an unstable air mass Thursday afternoon into Friday. ...Northern High Plains... Low pressure will develop over eastern WY during the afternoon with a wind shift over eastern MT. Southeast surface winds will maintain moist and unstable conditions over the Dakotas and Nebraska during the day, with continued northwestward warm advection during the evening with a 40-50 kt low-level jet. Steepening lapse rates aloft combined with sufficient deep-layer shear will support at least isolated severe storms capable of damaging hail. Locally damaging winds cannot be ruled out, although the majority of the storms are expected overnight. ..Jewell.. 09/17/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0122 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN GREAT BASIN... ...Synopsis... A large amplitude upper-level trough will move into the western CONUS on Wednesday. Strengthening mid-level flow around the base of this trough will overspread the dry airmass in the Great Basin Wednesday. Deep mixing during the afternoon will transport 20 to 25 mph winds to the surface where surface relative humidity is expected to be around 10 to 15 percent. These conditions support a critical fire weather delineation in portions of the southern Great Basin. In addition to these fire weather conditions, this strong upper-level trough will also bring significant rainfall to most of Oregon, Washington, and Idaho which should significantly reduce fire weather threat in these regions for at least a few weeks and could possibly serve as a season ending event for many areas, especially considering the significant rainfall totals across these areas during the past week. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN GREAT BASIN... ...Synopsis... A large amplitude upper-level trough will move into the western CONUS on Wednesday. Strengthening mid-level flow around the base of this trough will overspread the dry airmass in the Great Basin Wednesday. Deep mixing during the afternoon will transport 20 to 25 mph winds to the surface where surface relative humidity is expected to be around 10 to 15 percent. These conditions support a critical fire weather delineation in portions of the southern Great Basin. In addition to these fire weather conditions, this strong upper-level trough will also bring significant rainfall to most of Oregon, Washington, and Idaho which should significantly reduce fire weather threat in these regions for at least a few weeks and could possibly serve as a season ending event for many areas, especially considering the significant rainfall totals across these areas during the past week. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN GREAT BASIN... ...Synopsis... A large amplitude upper-level trough will move into the western CONUS on Wednesday. Strengthening mid-level flow around the base of this trough will overspread the dry airmass in the Great Basin Wednesday. Deep mixing during the afternoon will transport 20 to 25 mph winds to the surface where surface relative humidity is expected to be around 10 to 15 percent. These conditions support a critical fire weather delineation in portions of the southern Great Basin. In addition to these fire weather conditions, this strong upper-level trough will also bring significant rainfall to most of Oregon, Washington, and Idaho which should significantly reduce fire weather threat in these regions for at least a few weeks and could possibly serve as a season ending event for many areas, especially considering the significant rainfall totals across these areas during the past week. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SOUTHERN GREAT BASIN... ...Synopsis... A large amplitude upper-level trough will move into the western CONUS on Wednesday. Strengthening mid-level flow around the base of this trough will overspread the dry airmass in the Great Basin Wednesday. Deep mixing during the afternoon will transport 20 to 25 mph winds to the surface where surface relative humidity is expected to be around 10 to 15 percent. These conditions support a critical fire weather delineation in portions of the southern Great Basin. In addition to these fire weather conditions, this strong upper-level trough will also bring significant rainfall to most of Oregon, Washington, and Idaho which should significantly reduce fire weather threat in these regions for at least a few weeks and could possibly serve as a season ending event for many areas, especially considering the significant rainfall totals across these areas during the past week. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 171200Z - 181200Z ...Synopsis... A negatively tilted shortwave will move from northern Nevada into Wyoming today. At the surface, a cold front will move across the Great Basin and be present from southwest Wyoming southwestward into northwest Arizona by the afternoon. Deep mixing ahead of this cold front will transport stronger mid-level flow toward the surface with winds ranging from 20 to 35 mph with the strongest winds in central Wyoming. Relative humidity in this region should be in the 15 to 20 mph range. Therefore, a narrow corridor of elevated fire weather conditions are likely from northeast Arizona into central Wyoming and an elevated delineation highlights this area. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 171200Z - 181200Z ...Synopsis... A negatively tilted shortwave will move from northern Nevada into Wyoming today. At the surface, a cold front will move across the Great Basin and be present from southwest Wyoming southwestward into northwest Arizona by the afternoon. Deep mixing ahead of this cold front will transport stronger mid-level flow toward the surface with winds ranging from 20 to 35 mph with the strongest winds in central Wyoming. Relative humidity in this region should be in the 15 to 20 mph range. Therefore, a narrow corridor of elevated fire weather conditions are likely from northeast Arizona into central Wyoming and an elevated delineation highlights this area. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 171200Z - 181200Z ...Synopsis... A negatively tilted shortwave will move from northern Nevada into Wyoming today. At the surface, a cold front will move across the Great Basin and be present from southwest Wyoming southwestward into northwest Arizona by the afternoon. Deep mixing ahead of this cold front will transport stronger mid-level flow toward the surface with winds ranging from 20 to 35 mph with the strongest winds in central Wyoming. Relative humidity in this region should be in the 15 to 20 mph range. Therefore, a narrow corridor of elevated fire weather conditions are likely from northeast Arizona into central Wyoming and an elevated delineation highlights this area. ..Bentley.. 09/17/2019 ...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 0122 AM CDT Tue Sep 17 2019 Valid 171200Z - 181200Z ...Synopsis... A negatively tilted shortwave will move from northern Nevada into Wyoming today. At the surface, a cold front will move across the Great Basin and be present from southwest Wyoming southwestward into northwest Arizona by the afternoon. Deep mixing ahead of this cold front will transport stronger mid-level flow toward the surface with winds ranging from 20 to 35 mph with the strongest winds in central Wyoming. Relative humidity in this region should be in the 15 to 20 mph range. Therefore, a narrow corridor of elevated fire weather conditions are likely from northeast Arizona into central Wyoming and an elevated delineation highlights this area. ..Bentley.. 09/17/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather appears low. ...Synopsis... An upper trough will shift east across the Pacific Northwest and Great Basin, with strong upper-level southwesterlies and cooling aloft approaching the Rocky Mountains into Thursday morning. Ahead of this trough, a fast-moving, compact shortwave trough will move from MN into Ontario while an upper ridge remains over the mid and lower MS Valley. Beneath the upper ridge, a warm core disturbance is forecast to move into southeast TX, providing heavy precipitation. At the surface, a weak front will stall over the northern Plains behind the leading wave, with a moist air mass extending southwest to the Gulf of Mexico. ...Eastern NE into western WI... Storms may be ongoing Wednesday morning associated with a low-level jet and warm advection from IA into MN and northwest WI. Shear will be weak but plenty of instability will support heavy rain, gusty winds. Severe weather is not anticipated, but a locally strong wind gust or marginal hail report cannot be ruled out during the afternoon as isolated storms regenerate along the weak boundary. ...Upper TX Coast... A disturbance in the northwest Gulf of Mexico is forecast to move northwestward into southeast TX, with the primary concern very heavy rainfall. Predictability is low regarding wind fields and thus tornado risk. Should the system become stronger than currently forecast, shear profiles may necessitate low tornado probabilities in later outlooks. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 09/17/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 AM CDT Tue Sep 17 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather appears low. ...Synopsis... An upper trough will shift east across the Pacific Northwest and Great Basin, with strong upper-level southwesterlies and cooling aloft approaching the Rocky Mountains into Thursday morning. Ahead of this trough, a fast-moving, compact shortwave trough will move from MN into Ontario while an upper ridge remains over the mid and lower MS Valley. Beneath the upper ridge, a warm core disturbance is forecast to move into southeast TX, providing heavy precipitation. At the surface, a weak front will stall over the northern Plains behind the leading wave, with a moist air mass extending southwest to the Gulf of Mexico. ...Eastern NE into western WI... Storms may be ongoing Wednesday morning associated with a low-level jet and warm advection from IA into MN and northwest WI. Shear will be weak but plenty of instability will support heavy rain, gusty winds. Severe weather is not anticipated, but a locally strong wind gust or marginal hail report cannot be ruled out during the afternoon as isolated storms regenerate along the weak boundary. ...Upper TX Coast... A disturbance in the northwest Gulf of Mexico is forecast to move northwestward into southeast TX, with the primary concern very heavy rainfall. Predictability is low regarding wind fields and thus tornado risk. Should the system become stronger than currently forecast, shear profiles may necessitate low tornado probabilities in later outlooks. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: <5% - None Hail: <5% - None ..Jewell.. 09/17/2019 Read more