Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge axis will situate itself across the Pacific Northwest coast on D2/Tuesday. A surface anticyclone will continue on a southward track into central Rockies/High Plains along with the continued presence of a thermally induced pressure trough across the Oregon coast and northern California. The surface pressure pattern will continue to favor offshore flow across Oregon coast, with more of an easterly component than Monday. ...Western Oregon... Hot/dry conditions will be prevalent on Tuesday as strong heating occurs underneath the upper-level ridge. Easterly downslope flow off the Cascades will help reduce afternoon RH values to potentially below 20% in some locations, but more broadly 25-35%. Wind speed still appears to be the limiting factor to a greater threat for fire spread. However, a probable location for locally elevated concerns will be northern portions of the Willamette Valley where terrain-enhanced flow out of the Columbia Gorge will bring potential for 15-20 mph winds. Elsewhere within western Oregon, 10-15 mph are more likely. ..Wendt.. 08/26/2019 ...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 0149 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge axis will situate itself across the Pacific Northwest coast on D2/Tuesday. A surface anticyclone will continue on a southward track into central Rockies/High Plains along with the continued presence of a thermally induced pressure trough across the Oregon coast and northern California. The surface pressure pattern will continue to favor offshore flow across Oregon coast, with more of an easterly component than Monday. ...Western Oregon... Hot/dry conditions will be prevalent on Tuesday as strong heating occurs underneath the upper-level ridge. Easterly downslope flow off the Cascades will help reduce afternoon RH values to potentially below 20% in some locations, but more broadly 25-35%. Wind speed still appears to be the limiting factor to a greater threat for fire spread. However, a probable location for locally elevated concerns will be northern portions of the Willamette Valley where terrain-enhanced flow out of the Columbia Gorge will bring potential for 15-20 mph winds. Elsewhere within western Oregon, 10-15 mph are more likely. ..Wendt.. 08/26/2019 ...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 0149 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge axis will situate itself across the Pacific Northwest coast on D2/Tuesday. A surface anticyclone will continue on a southward track into central Rockies/High Plains along with the continued presence of a thermally induced pressure trough across the Oregon coast and northern California. The surface pressure pattern will continue to favor offshore flow across Oregon coast, with more of an easterly component than Monday. ...Western Oregon... Hot/dry conditions will be prevalent on Tuesday as strong heating occurs underneath the upper-level ridge. Easterly downslope flow off the Cascades will help reduce afternoon RH values to potentially below 20% in some locations, but more broadly 25-35%. Wind speed still appears to be the limiting factor to a greater threat for fire spread. However, a probable location for locally elevated concerns will be northern portions of the Willamette Valley where terrain-enhanced flow out of the Columbia Gorge will bring potential for 15-20 mph winds. Elsewhere within western Oregon, 10-15 mph are more likely. ..Wendt.. 08/26/2019 ...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 0149 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... ...Synopsis... The upper-level ridge axis will situate itself across the Pacific Northwest coast on D2/Tuesday. A surface anticyclone will continue on a southward track into central Rockies/High Plains along with the continued presence of a thermally induced pressure trough across the Oregon coast and northern California. The surface pressure pattern will continue to favor offshore flow across Oregon coast, with more of an easterly component than Monday. ...Western Oregon... Hot/dry conditions will be prevalent on Tuesday as strong heating occurs underneath the upper-level ridge. Easterly downslope flow off the Cascades will help reduce afternoon RH values to potentially below 20% in some locations, but more broadly 25-35%. Wind speed still appears to be the limiting factor to a greater threat for fire spread. However, a probable location for locally elevated concerns will be northern portions of the Willamette Valley where terrain-enhanced flow out of the Columbia Gorge will bring potential for 15-20 mph winds. Elsewhere within western Oregon, 10-15 mph are more likely. ..Wendt.. 08/26/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0621 Status Updates
STATUS REPORT ON WW 621 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 N LBF TO 30 SE MHN TO 35 E MHN TO 45 WNW MHN TO 55 WNW VTN. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1861 ..GLEASON..08/26/19 ATTN...WFO...LBF... STATUS REPORT FOR WS 621 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS NEC009-015-017-031-041-071-089-103-113-115-149-171-183-260740- NE . NEBRASKA COUNTIES INCLUDED ARE BLAINE BOYD BROWN CHERRY CUSTER GARFIELD HOLT KEYA PAHA LOGAN LOUP ROCK THOMAS WHEELER 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 0620 Status Updates
STATUS REPORT ON WW 620 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 WNW VTN TO 30 N PIR. WW 620 WILL BE ALLOWED TO EXPIRE AT 260700Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1861 ..GLEASON..08/26/19 ATTN...WFO...UNR... STATUS REPORT FOR WS 620 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-095-121-123-260700- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MELLETTE TODD TRIPP 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 0620 Status Updates
STATUS REPORT ON WW 620 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 WNW VTN TO 30 N PIR. WW 620 WILL BE ALLOWED TO EXPIRE AT 260700Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1861 ..GLEASON..08/26/19 ATTN...WFO...UNR... STATUS REPORT FOR WS 620 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-095-121-123-260700- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MELLETTE TODD TRIPP 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 0620 Status Updates
STATUS REPORT ON WW 620 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 WNW VTN TO 30 N PIR. WW 620 WILL BE ALLOWED TO EXPIRE AT 260700Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1861 ..GLEASON..08/26/19 ATTN...WFO...UNR... STATUS REPORT FOR WS 620 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-095-121-123-260700- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MELLETTE TODD TRIPP 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 0620 Status Updates
STATUS REPORT ON WW 620 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 WNW VTN TO 30 N PIR. WW 620 WILL BE ALLOWED TO EXPIRE AT 260700Z. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 1861 ..GLEASON..08/26/19 ATTN...WFO...UNR... STATUS REPORT FOR WS 620 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS SDC007-055-071-095-121-123-260700- SD . SOUTH DAKOTA COUNTIES INCLUDED ARE BENNETT HAAKON JACKSON MELLETTE TODD TRIPP 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

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0112 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... A broad upper-level trough will continue to move east through the central Rockies today, with remnant enhanced mid-level flow along the back edge of this feature. An upper-level ridge will again build across the Pacific Northwest coast. At the surface, an anticyclone will build within the northern Rockies as a thermally induced pressure trough sets up across northern California into parts of the Oregon coast. While fire weather concerns will be greatly reduced from Sunday, a few areas of locally elevated conditions are probable. ...Southwestern Wyoming and Central Utah... With some stronger northwesterly flow aloft, areas of southwestern Wyoming and within the lee of the Wasatch range may experience 15-20 mph winds, with potentially higher gusts, during the afternoon. These conditions, however, are not expected to be widespread or long-lasting as surface pressure gradient remains weak under the influence of the anticyclone. ...Willamette Valley Vicinity... The surface pressure pattern will favor offshore flow across much of the Oregon coast, particularly during the evening and overnight hours. Guidance differs on how low the RH will fall (most likely 25-35%), but there is ample agreement that sustained 15 mph winds will be localized in nature. Dry offshore flow may also occur in southwestern Oregon, but confidence in even locally elevated conditions is less farther south. ..Wendt.. 08/26/2019 ...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 0112 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... A broad upper-level trough will continue to move east through the central Rockies today, with remnant enhanced mid-level flow along the back edge of this feature. An upper-level ridge will again build across the Pacific Northwest coast. At the surface, an anticyclone will build within the northern Rockies as a thermally induced pressure trough sets up across northern California into parts of the Oregon coast. While fire weather concerns will be greatly reduced from Sunday, a few areas of locally elevated conditions are probable. ...Southwestern Wyoming and Central Utah... With some stronger northwesterly flow aloft, areas of southwestern Wyoming and within the lee of the Wasatch range may experience 15-20 mph winds, with potentially higher gusts, during the afternoon. These conditions, however, are not expected to be widespread or long-lasting as surface pressure gradient remains weak under the influence of the anticyclone. ...Willamette Valley Vicinity... The surface pressure pattern will favor offshore flow across much of the Oregon coast, particularly during the evening and overnight hours. Guidance differs on how low the RH will fall (most likely 25-35%), but there is ample agreement that sustained 15 mph winds will be localized in nature. Dry offshore flow may also occur in southwestern Oregon, but confidence in even locally elevated conditions is less farther south. ..Wendt.. 08/26/2019 ...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 0112 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... A broad upper-level trough will continue to move east through the central Rockies today, with remnant enhanced mid-level flow along the back edge of this feature. An upper-level ridge will again build across the Pacific Northwest coast. At the surface, an anticyclone will build within the northern Rockies as a thermally induced pressure trough sets up across northern California into parts of the Oregon coast. While fire weather concerns will be greatly reduced from Sunday, a few areas of locally elevated conditions are probable. ...Southwestern Wyoming and Central Utah... With some stronger northwesterly flow aloft, areas of southwestern Wyoming and within the lee of the Wasatch range may experience 15-20 mph winds, with potentially higher gusts, during the afternoon. These conditions, however, are not expected to be widespread or long-lasting as surface pressure gradient remains weak under the influence of the anticyclone. ...Willamette Valley Vicinity... The surface pressure pattern will favor offshore flow across much of the Oregon coast, particularly during the evening and overnight hours. Guidance differs on how low the RH will fall (most likely 25-35%), but there is ample agreement that sustained 15 mph winds will be localized in nature. Dry offshore flow may also occur in southwestern Oregon, but confidence in even locally elevated conditions is less farther south. ..Wendt.. 08/26/2019 ...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 0112 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... A broad upper-level trough will continue to move east through the central Rockies today, with remnant enhanced mid-level flow along the back edge of this feature. An upper-level ridge will again build across the Pacific Northwest coast. At the surface, an anticyclone will build within the northern Rockies as a thermally induced pressure trough sets up across northern California into parts of the Oregon coast. While fire weather concerns will be greatly reduced from Sunday, a few areas of locally elevated conditions are probable. ...Southwestern Wyoming and Central Utah... With some stronger northwesterly flow aloft, areas of southwestern Wyoming and within the lee of the Wasatch range may experience 15-20 mph winds, with potentially higher gusts, during the afternoon. These conditions, however, are not expected to be widespread or long-lasting as surface pressure gradient remains weak under the influence of the anticyclone. ...Willamette Valley Vicinity... The surface pressure pattern will favor offshore flow across much of the Oregon coast, particularly during the evening and overnight hours. Guidance differs on how low the RH will fall (most likely 25-35%), but there is ample agreement that sustained 15 mph winds will be localized in nature. Dry offshore flow may also occur in southwestern Oregon, but confidence in even locally elevated conditions is less farther south. ..Wendt.. 08/26/2019 ...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 1246 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST TEXAS/SOUTHWEST OKLAHOMA SOUTHEASTWARD INTO WESTERN LOUISIANA... ...SUMMARY... Isolated severe thunderstorms are possible from northwest Texas/southwest Oklahoma southeastward into western Louisiana on Tuesday. ...Synopsis... Maturing mid-latitude cyclone, centered near the southern Manitoba/Ontario border early Tuesday morning, is expected continue eastward into far northwest Ontario. Expansive cyclonic flow throughout the base of this system (and attendant enhanced westerly flow aloft) will also progress eastward over the upper/middle MS Valleys into the OH Valley. Surface low attendant to this upper system is expected to be centered over northwestern Ontario Tuesday morning. A cold front will extend southeastward from this low into the Upper Great Lakes then southwestward through the middle MS Valley into southwest TX. Northern/eastern portion of this front will remain progressive, continuing eastward through the OH Valley and Lower Great Lakes. Southern/western portion of this front will be less progressive with outflow from an MCS likely becoming the effective boundary across southern OK/northern TX. ...Far Northwest TX/Southeast OK into Western LA... Showers and thunderstorm will likely be ongoing at the beginning of the period as a decaying MCS moves into the region. Isolated damaging wind gusts are possible with the strongest cells along the outflow boundary. Warm and moist conditions are anticipated south of the composite outflow boundary Tuesday afternoon. Mid-level temperatures will be relatively warm, but the warm and moist low-levels will likely result in an erosion of any convective inhibition. Convergence along the boundary will then lead to thunderstorm development. However, given the mesoscale nature of this boundary, its location is hard to ascertain with much confidence at this point. Most of the convection-allowing guidance suggests a more southerly boundary location during the afternoon and the 5% threat area was adjusted accordingly. The lack of stronger vertical shear suggests minimal storm organization and a predominantly multicellular mode. Even so, strong water-loaded downbursts are possible with the strongest updrafts. ...Upper Midwest... A shortwave trough embedded within the base of the larger parent mid-latitude cyclone is expected to move into the region during the afternoon. Cool mid-level temperatures and large-scale forcing for ascent associated with this trough will led to thunderstorm development. Given the weak instability, storms are generally expected to remain sub-severe with some small hail possible within the strongest updrafts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/26/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST TEXAS/SOUTHWEST OKLAHOMA SOUTHEASTWARD INTO WESTERN LOUISIANA... ...SUMMARY... Isolated severe thunderstorms are possible from northwest Texas/southwest Oklahoma southeastward into western Louisiana on Tuesday. ...Synopsis... Maturing mid-latitude cyclone, centered near the southern Manitoba/Ontario border early Tuesday morning, is expected continue eastward into far northwest Ontario. Expansive cyclonic flow throughout the base of this system (and attendant enhanced westerly flow aloft) will also progress eastward over the upper/middle MS Valleys into the OH Valley. Surface low attendant to this upper system is expected to be centered over northwestern Ontario Tuesday morning. A cold front will extend southeastward from this low into the Upper Great Lakes then southwestward through the middle MS Valley into southwest TX. Northern/eastern portion of this front will remain progressive, continuing eastward through the OH Valley and Lower Great Lakes. Southern/western portion of this front will be less progressive with outflow from an MCS likely becoming the effective boundary across southern OK/northern TX. ...Far Northwest TX/Southeast OK into Western LA... Showers and thunderstorm will likely be ongoing at the beginning of the period as a decaying MCS moves into the region. Isolated damaging wind gusts are possible with the strongest cells along the outflow boundary. Warm and moist conditions are anticipated south of the composite outflow boundary Tuesday afternoon. Mid-level temperatures will be relatively warm, but the warm and moist low-levels will likely result in an erosion of any convective inhibition. Convergence along the boundary will then lead to thunderstorm development. However, given the mesoscale nature of this boundary, its location is hard to ascertain with much confidence at this point. Most of the convection-allowing guidance suggests a more southerly boundary location during the afternoon and the 5% threat area was adjusted accordingly. The lack of stronger vertical shear suggests minimal storm organization and a predominantly multicellular mode. Even so, strong water-loaded downbursts are possible with the strongest updrafts. ...Upper Midwest... A shortwave trough embedded within the base of the larger parent mid-latitude cyclone is expected to move into the region during the afternoon. Cool mid-level temperatures and large-scale forcing for ascent associated with this trough will led to thunderstorm development. Given the weak instability, storms are generally expected to remain sub-severe with some small hail possible within the strongest updrafts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/26/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST TEXAS/SOUTHWEST OKLAHOMA SOUTHEASTWARD INTO WESTERN LOUISIANA... ...SUMMARY... Isolated severe thunderstorms are possible from northwest Texas/southwest Oklahoma southeastward into western Louisiana on Tuesday. ...Synopsis... Maturing mid-latitude cyclone, centered near the southern Manitoba/Ontario border early Tuesday morning, is expected continue eastward into far northwest Ontario. Expansive cyclonic flow throughout the base of this system (and attendant enhanced westerly flow aloft) will also progress eastward over the upper/middle MS Valleys into the OH Valley. Surface low attendant to this upper system is expected to be centered over northwestern Ontario Tuesday morning. A cold front will extend southeastward from this low into the Upper Great Lakes then southwestward through the middle MS Valley into southwest TX. Northern/eastern portion of this front will remain progressive, continuing eastward through the OH Valley and Lower Great Lakes. Southern/western portion of this front will be less progressive with outflow from an MCS likely becoming the effective boundary across southern OK/northern TX. ...Far Northwest TX/Southeast OK into Western LA... Showers and thunderstorm will likely be ongoing at the beginning of the period as a decaying MCS moves into the region. Isolated damaging wind gusts are possible with the strongest cells along the outflow boundary. Warm and moist conditions are anticipated south of the composite outflow boundary Tuesday afternoon. Mid-level temperatures will be relatively warm, but the warm and moist low-levels will likely result in an erosion of any convective inhibition. Convergence along the boundary will then lead to thunderstorm development. However, given the mesoscale nature of this boundary, its location is hard to ascertain with much confidence at this point. Most of the convection-allowing guidance suggests a more southerly boundary location during the afternoon and the 5% threat area was adjusted accordingly. The lack of stronger vertical shear suggests minimal storm organization and a predominantly multicellular mode. Even so, strong water-loaded downbursts are possible with the strongest updrafts. ...Upper Midwest... A shortwave trough embedded within the base of the larger parent mid-latitude cyclone is expected to move into the region during the afternoon. Cool mid-level temperatures and large-scale forcing for ascent associated with this trough will led to thunderstorm development. Given the weak instability, storms are generally expected to remain sub-severe with some small hail possible within the strongest updrafts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/26/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Mon Aug 26 2019 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST TEXAS/SOUTHWEST OKLAHOMA SOUTHEASTWARD INTO WESTERN LOUISIANA... ...SUMMARY... Isolated severe thunderstorms are possible from northwest Texas/southwest Oklahoma southeastward into western Louisiana on Tuesday. ...Synopsis... Maturing mid-latitude cyclone, centered near the southern Manitoba/Ontario border early Tuesday morning, is expected continue eastward into far northwest Ontario. Expansive cyclonic flow throughout the base of this system (and attendant enhanced westerly flow aloft) will also progress eastward over the upper/middle MS Valleys into the OH Valley. Surface low attendant to this upper system is expected to be centered over northwestern Ontario Tuesday morning. A cold front will extend southeastward from this low into the Upper Great Lakes then southwestward through the middle MS Valley into southwest TX. Northern/eastern portion of this front will remain progressive, continuing eastward through the OH Valley and Lower Great Lakes. Southern/western portion of this front will be less progressive with outflow from an MCS likely becoming the effective boundary across southern OK/northern TX. ...Far Northwest TX/Southeast OK into Western LA... Showers and thunderstorm will likely be ongoing at the beginning of the period as a decaying MCS moves into the region. Isolated damaging wind gusts are possible with the strongest cells along the outflow boundary. Warm and moist conditions are anticipated south of the composite outflow boundary Tuesday afternoon. Mid-level temperatures will be relatively warm, but the warm and moist low-levels will likely result in an erosion of any convective inhibition. Convergence along the boundary will then lead to thunderstorm development. However, given the mesoscale nature of this boundary, its location is hard to ascertain with much confidence at this point. Most of the convection-allowing guidance suggests a more southerly boundary location during the afternoon and the 5% threat area was adjusted accordingly. The lack of stronger vertical shear suggests minimal storm organization and a predominantly multicellular mode. Even so, strong water-loaded downbursts are possible with the strongest updrafts. ...Upper Midwest... A shortwave trough embedded within the base of the larger parent mid-latitude cyclone is expected to move into the region during the afternoon. Cool mid-level temperatures and large-scale forcing for ascent associated with this trough will led to thunderstorm development. Given the weak instability, storms are generally expected to remain sub-severe with some small hail possible within the strongest updrafts. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/26/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MISSOURI SOUTHWESTWARD INTO NORTHEAST OKLAHOMA... ...SUMMARY... Severe thunderstorms are expected this afternoon through the evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail, severe gusts, and a few tornadoes are possible before the threat transitions to mainly a risk for severe gusts and wind damage tonight. ...Lower MO Valley into OK... A mid-level trough over the Upper Midwest today will evolve into a closed low near the MN/Canada border by early Tuesday. A belt of strong westerly 500mb flow will overspread the lower MO Valley during the day. A complicating factor for this forecast will involve an MCS over the north-central Plains which is forecast to move into the lower MO Valley during the morning hours. Model guidance generally depicts this scenario with some severe risk perhaps ongoing early this morning before possibly waning with the MCS dissipating over the lower MO Valley. Renewed storm development is likely by late afternoon along a cold front forecast to move southeast across the central Great Plains and lower MO Valley. The intersection of possible earlier-day outflow with the front may serve as a preferred storm initiation zone before additional storms develop along the southwest-northeast oriented boundary. The pre-convective airmass is forecast to become very unstable from central OK northeast into eastern KS and MO with MLCAPE ranging from 3000-4000 J/kg. An initial window of opportunity (2 hours) may exist for a supercell risk capable of all hazards. Precipitable water around 2 inches and large CAPE, a wind profile strengthening from the low into the midlevels (40-50kt) and weakening in the high levels, and strong agreement of convection-allowing model guidance all suggest a relatively quick transition to a linear band of storms from northern MO zippering southwest into central OK during the evening. Wind damage from severe gusts will likely become most prevalent during the cellular to squall line transition (possible HP supercells) and the initial 1-3 hours afterwards during the evening. A gradual diminishing in storm intensity and potential severe coverage is expected by late evening into the overnight as storms move to the MS river and the Ark-La-Tex. ..Smith/Wendt.. 08/26/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MISSOURI SOUTHWESTWARD INTO NORTHEAST OKLAHOMA... ...SUMMARY... Severe thunderstorms are expected this afternoon through the evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail, severe gusts, and a few tornadoes are possible before the threat transitions to mainly a risk for severe gusts and wind damage tonight. ...Lower MO Valley into OK... A mid-level trough over the Upper Midwest today will evolve into a closed low near the MN/Canada border by early Tuesday. A belt of strong westerly 500mb flow will overspread the lower MO Valley during the day. A complicating factor for this forecast will involve an MCS over the north-central Plains which is forecast to move into the lower MO Valley during the morning hours. Model guidance generally depicts this scenario with some severe risk perhaps ongoing early this morning before possibly waning with the MCS dissipating over the lower MO Valley. Renewed storm development is likely by late afternoon along a cold front forecast to move southeast across the central Great Plains and lower MO Valley. The intersection of possible earlier-day outflow with the front may serve as a preferred storm initiation zone before additional storms develop along the southwest-northeast oriented boundary. The pre-convective airmass is forecast to become very unstable from central OK northeast into eastern KS and MO with MLCAPE ranging from 3000-4000 J/kg. An initial window of opportunity (2 hours) may exist for a supercell risk capable of all hazards. Precipitable water around 2 inches and large CAPE, a wind profile strengthening from the low into the midlevels (40-50kt) and weakening in the high levels, and strong agreement of convection-allowing model guidance all suggest a relatively quick transition to a linear band of storms from northern MO zippering southwest into central OK during the evening. Wind damage from severe gusts will likely become most prevalent during the cellular to squall line transition (possible HP supercells) and the initial 1-3 hours afterwards during the evening. A gradual diminishing in storm intensity and potential severe coverage is expected by late evening into the overnight as storms move to the MS river and the Ark-La-Tex. ..Smith/Wendt.. 08/26/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Mon Aug 26 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MISSOURI SOUTHWESTWARD INTO NORTHEAST OKLAHOMA... ...SUMMARY... Severe thunderstorms are expected this afternoon through the evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail, severe gusts, and a few tornadoes are possible before the threat transitions to mainly a risk for severe gusts and wind damage tonight. ...Lower MO Valley into OK... A mid-level trough over the Upper Midwest today will evolve into a closed low near the MN/Canada border by early Tuesday. A belt of strong westerly 500mb flow will overspread the lower MO Valley during the day. A complicating factor for this forecast will involve an MCS over the north-central Plains which is forecast to move into the lower MO Valley during the morning hours. Model guidance generally depicts this scenario with some severe risk perhaps ongoing early this morning before possibly waning with the MCS dissipating over the lower MO Valley. Renewed storm development is likely by late afternoon along a cold front forecast to move southeast across the central Great Plains and lower MO Valley. The intersection of possible earlier-day outflow with the front may serve as a preferred storm initiation zone before additional storms develop along the southwest-northeast oriented boundary. The pre-convective airmass is forecast to become very unstable from central OK northeast into eastern KS and MO with MLCAPE ranging from 3000-4000 J/kg. An initial window of opportunity (2 hours) may exist for a supercell risk capable of all hazards. Precipitable water around 2 inches and large CAPE, a wind profile strengthening from the low into the midlevels (40-50kt) and weakening in the high levels, and strong agreement of convection-allowing model guidance all suggest a relatively quick transition to a linear band of storms from northern MO zippering southwest into central OK during the evening. Wind damage from severe gusts will likely become most prevalent during the cellular to squall line transition (possible HP supercells) and the initial 1-3 hours afterwards during the evening. A gradual diminishing in storm intensity and potential severe coverage is expected by late evening into the overnight as storms move to the MS river and the Ark-La-Tex. ..Smith/Wendt.. 08/26/2019 Read more