Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sun Aug 25 2019 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A THE CENTRAL DAKOTAS INTO EXTREME NORTHERN NEBRASKA... ...SUMMARY... Thunderstorms with isolated large hail and a few damaging gusts are expected mainly over the central Dakotas this afternoon/evening into northern Nebraska overnight. ...Discussion... Primary change to this outlook has been to continue to trim the eastern bound of the SLGT across ND primarily due to thermodynamic concerns related to the widespread stratus that has been slow to erode. Have also dropped the MRGL risk area over the lower MS Valley region, as much of the airmass is in the process of being overturned by numerous multicell storms. Otherwise, expect storms to develop along the pre-frontal trough over the Dakotas this afternoon. Here, the atmosphere has become moderately unstable (1500-2000 J/kg MLCAPE), and vertical wind profiles with 30-40 kt effective bulk shear should support a few supercell structures, but eventually evolving into multicell line segments. Reference SWOMCD 1857 for more details. ..Dial.. 08/25/2019 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Aug 25 2019/ ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sun Aug 25 2019 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A THE CENTRAL DAKOTAS INTO EXTREME NORTHERN NEBRASKA... ...SUMMARY... Thunderstorms with isolated large hail and a few damaging gusts are expected mainly over the central Dakotas this afternoon/evening into northern Nebraska overnight. ...Discussion... Primary change to this outlook has been to continue to trim the eastern bound of the SLGT across ND primarily due to thermodynamic concerns related to the widespread stratus that has been slow to erode. Have also dropped the MRGL risk area over the lower MS Valley region, as much of the airmass is in the process of being overturned by numerous multicell storms. Otherwise, expect storms to develop along the pre-frontal trough over the Dakotas this afternoon. Here, the atmosphere has become moderately unstable (1500-2000 J/kg MLCAPE), and vertical wind profiles with 30-40 kt effective bulk shear should support a few supercell structures, but eventually evolving into multicell line segments. Reference SWOMCD 1857 for more details. ..Dial.. 08/25/2019 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Aug 25 2019/ ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sun Aug 25 2019 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A THE CENTRAL DAKOTAS INTO EXTREME NORTHERN NEBRASKA... ...SUMMARY... Thunderstorms with isolated large hail and a few damaging gusts are expected mainly over the central Dakotas this afternoon/evening into northern Nebraska overnight. ...Discussion... Primary change to this outlook has been to continue to trim the eastern bound of the SLGT across ND primarily due to thermodynamic concerns related to the widespread stratus that has been slow to erode. Have also dropped the MRGL risk area over the lower MS Valley region, as much of the airmass is in the process of being overturned by numerous multicell storms. Otherwise, expect storms to develop along the pre-frontal trough over the Dakotas this afternoon. Here, the atmosphere has become moderately unstable (1500-2000 J/kg MLCAPE), and vertical wind profiles with 30-40 kt effective bulk shear should support a few supercell structures, but eventually evolving into multicell line segments. Reference SWOMCD 1857 for more details. ..Dial.. 08/25/2019 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Aug 25 2019/ ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sun Aug 25 2019 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A THE CENTRAL DAKOTAS INTO EXTREME NORTHERN NEBRASKA... ...SUMMARY... Thunderstorms with isolated large hail and a few damaging gusts are expected mainly over the central Dakotas this afternoon/evening into northern Nebraska overnight. ...Discussion... Primary change to this outlook has been to continue to trim the eastern bound of the SLGT across ND primarily due to thermodynamic concerns related to the widespread stratus that has been slow to erode. Have also dropped the MRGL risk area over the lower MS Valley region, as much of the airmass is in the process of being overturned by numerous multicell storms. Otherwise, expect storms to develop along the pre-frontal trough over the Dakotas this afternoon. Here, the atmosphere has become moderately unstable (1500-2000 J/kg MLCAPE), and vertical wind profiles with 30-40 kt effective bulk shear should support a few supercell structures, but eventually evolving into multicell line segments. Reference SWOMCD 1857 for more details. ..Dial.. 08/25/2019 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Aug 25 2019/ ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. Read more

MD 1857 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF NORTH DAKOTA AND SOUTH DAKOTA
Mesoscale Discussion 1857 NWS Storm Prediction Center Norman OK 0250 PM CDT Sun Aug 25 2019 Areas affected...portions of North Dakota and South Dakota Concerning...Severe potential...Watch likely Valid 251950Z - 252145Z Probability of Watch Issuance...80 percent SUMMARY...Observational trends and model guidance suggest that a Severe Thunderstorm Watch will be needed by around 21Z or so. DISCUSSION...Latest objective analyses and satellite imagery suggests a destabilizing atmosphere especially across western portions of the discussion area, with insolation now yielding towering cumulus near/east of ISN through west of BIS. Warming surface temperatures (into the 80s F) was contributing to MUCAPE values around 2000-3000 J/kg amidst steep (7-8C/km) mid-level lapse rates and modest (30-40 kt) deep shear. Meanwhile, a weak mid-level shortwave trough over eastern Montana was approaching the region from the west, which should provide additional ascent/cooling aloft and further aid in convective initiation. The region also resides beneath the exit region of a gradually strengthening mid-level jet that should impinge on the region through tonight. Latest thinking is that storms will continue to increase in coverage and intensity over the course of the afternoon and will likely grow upscale into a mix of cells and clusters as cold pools mature amidst modest low-level shear. Severe hail and damaging wind gusts will be the most probable threats with this activity. The threat will be widespread enough to necessitate a WW issuance, and this will be coordinated with affected WFOs during the 20-21Z window. ..Cook/Thompson.. 08/25/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS...UNR... LAT...LON 48930223 49150150 49080000 48469939 46859919 44819915 43639967 43260028 43250116 43330191 43710260 44790309 45810302 47560273 48930223 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... Locally elevated conditions remain possible across southern Wyoming into portions of eastern Utah and western Colorado. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 25 2019/ ...Synopsis... Broad upper-level cyclonic flow will shift eastward into the northern Plains/upper-Midwest during the D2/Monday period. At the surface, high pressure will build into parts of the Pacific Northwest and northern Rockies with a thermally-induced pressure trough present across northern California. With mid-level winds waning across areas of dry fuels, as well as a generally weak surface pressure gradient across the northwestern quarter of the CONUS, fire weather concerns will be reduced below elevated levels in most locations. Locally elevated conditions will be most likely in portions of southern Wyoming and perhaps the Snake River Valley where some residual mid-level flow will exist. However, conditions are expected to be relatively brief and occur over areas with a general lack of fuels. With higher pressure over Montana and a pressure trough along the Oregon coast, portions of the Willamette Valley will see easterly downslope flow during the evening/overnight. RH values may dip to 30-35%. Based on available guidance, winds do not appear likely reach the sustained 15 mph threshold except on a localized basis. ...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 0218 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... Locally elevated conditions remain possible across southern Wyoming into portions of eastern Utah and western Colorado. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 25 2019/ ...Synopsis... Broad upper-level cyclonic flow will shift eastward into the northern Plains/upper-Midwest during the D2/Monday period. At the surface, high pressure will build into parts of the Pacific Northwest and northern Rockies with a thermally-induced pressure trough present across northern California. With mid-level winds waning across areas of dry fuels, as well as a generally weak surface pressure gradient across the northwestern quarter of the CONUS, fire weather concerns will be reduced below elevated levels in most locations. Locally elevated conditions will be most likely in portions of southern Wyoming and perhaps the Snake River Valley where some residual mid-level flow will exist. However, conditions are expected to be relatively brief and occur over areas with a general lack of fuels. With higher pressure over Montana and a pressure trough along the Oregon coast, portions of the Willamette Valley will see easterly downslope flow during the evening/overnight. RH values may dip to 30-35%. Based on available guidance, winds do not appear likely reach the sustained 15 mph threshold except on a localized basis. ...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 0218 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... Locally elevated conditions remain possible across southern Wyoming into portions of eastern Utah and western Colorado. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 25 2019/ ...Synopsis... Broad upper-level cyclonic flow will shift eastward into the northern Plains/upper-Midwest during the D2/Monday period. At the surface, high pressure will build into parts of the Pacific Northwest and northern Rockies with a thermally-induced pressure trough present across northern California. With mid-level winds waning across areas of dry fuels, as well as a generally weak surface pressure gradient across the northwestern quarter of the CONUS, fire weather concerns will be reduced below elevated levels in most locations. Locally elevated conditions will be most likely in portions of southern Wyoming and perhaps the Snake River Valley where some residual mid-level flow will exist. However, conditions are expected to be relatively brief and occur over areas with a general lack of fuels. With higher pressure over Montana and a pressure trough along the Oregon coast, portions of the Willamette Valley will see easterly downslope flow during the evening/overnight. RH values may dip to 30-35%. Based on available guidance, winds do not appear likely reach the sustained 15 mph threshold except on a localized basis. ...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 0218 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... Locally elevated conditions remain possible across southern Wyoming into portions of eastern Utah and western Colorado. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 25 2019/ ...Synopsis... Broad upper-level cyclonic flow will shift eastward into the northern Plains/upper-Midwest during the D2/Monday period. At the surface, high pressure will build into parts of the Pacific Northwest and northern Rockies with a thermally-induced pressure trough present across northern California. With mid-level winds waning across areas of dry fuels, as well as a generally weak surface pressure gradient across the northwestern quarter of the CONUS, fire weather concerns will be reduced below elevated levels in most locations. Locally elevated conditions will be most likely in portions of southern Wyoming and perhaps the Snake River Valley where some residual mid-level flow will exist. However, conditions are expected to be relatively brief and occur over areas with a general lack of fuels. With higher pressure over Montana and a pressure trough along the Oregon coast, portions of the Willamette Valley will see easterly downslope flow during the evening/overnight. RH values may dip to 30-35%. Based on available guidance, winds do not appear likely reach the sustained 15 mph threshold except on a localized basis. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OKLAHOMA...EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms are expected Monday afternoon and evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail and damaging winds should be the main threats, though a few tornadoes are also possible. ...Synopsis... A broad low-amplitude upper trough now situated from southwestern Canada into the northern Rockies is forecast to undergo significant amplification as it moves through the northern Plains and upper MS Valley region Monday. This feature will be accompanied by a cold front that should extend from MN, eastern KS, northwest OK into the TX Panhandle by late tomorrow afternoon. A warm front will advance northward reaching northern MO early in the period. ...Middle MS Valley region through eastern Kansas and Oklahoma... Ascent with a leading vorticity maximum embedded within the amplifying upper trough will likely contribute to a few storms early in the period, mainly from eastern NE into IA. A few instances of hail and locally strong wind gusts cannot be ruled out with this activity. South of the early storms, the moistening warm sector will become strongly unstable with low to mid 70s F dewpoints beneath 7-7.5 C/km mid-level lapse rates, and diabatic warming of the boundary layer contributing to 3000-4000 J/kg MLCAPE. Wind profiles will strengthen in association with the amplifying trough with 35-45 kt effective bulk shear. Storms are expected to redevelop along the cold front, initially over northeast KS into northwest MO and move east through MO. A broken band of storms with mixed modes including supercells and line segments appears likely with large hail and damaging wind. A few tornadoes may be possible especially over northern MO where remnant boundary from early activity might augment 0-2 km storm relative helicity. Backbuilding into OK is expected as the front continues south during the evening. Though wind profiles will be weaker with southwestern extent into OK, the thermodynamic environment with strong instability and steep lapse rates will support a risk for large hail and downburst winds. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 30% - Enhanced ..Dial.. 08/25/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OKLAHOMA...EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms are expected Monday afternoon and evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail and damaging winds should be the main threats, though a few tornadoes are also possible. ...Synopsis... A broad low-amplitude upper trough now situated from southwestern Canada into the northern Rockies is forecast to undergo significant amplification as it moves through the northern Plains and upper MS Valley region Monday. This feature will be accompanied by a cold front that should extend from MN, eastern KS, northwest OK into the TX Panhandle by late tomorrow afternoon. A warm front will advance northward reaching northern MO early in the period. ...Middle MS Valley region through eastern Kansas and Oklahoma... Ascent with a leading vorticity maximum embedded within the amplifying upper trough will likely contribute to a few storms early in the period, mainly from eastern NE into IA. A few instances of hail and locally strong wind gusts cannot be ruled out with this activity. South of the early storms, the moistening warm sector will become strongly unstable with low to mid 70s F dewpoints beneath 7-7.5 C/km mid-level lapse rates, and diabatic warming of the boundary layer contributing to 3000-4000 J/kg MLCAPE. Wind profiles will strengthen in association with the amplifying trough with 35-45 kt effective bulk shear. Storms are expected to redevelop along the cold front, initially over northeast KS into northwest MO and move east through MO. A broken band of storms with mixed modes including supercells and line segments appears likely with large hail and damaging wind. A few tornadoes may be possible especially over northern MO where remnant boundary from early activity might augment 0-2 km storm relative helicity. Backbuilding into OK is expected as the front continues south during the evening. Though wind profiles will be weaker with southwestern extent into OK, the thermodynamic environment with strong instability and steep lapse rates will support a risk for large hail and downburst winds. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 30% - Enhanced ..Dial.. 08/25/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OKLAHOMA...EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms are expected Monday afternoon and evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail and damaging winds should be the main threats, though a few tornadoes are also possible. ...Synopsis... A broad low-amplitude upper trough now situated from southwestern Canada into the northern Rockies is forecast to undergo significant amplification as it moves through the northern Plains and upper MS Valley region Monday. This feature will be accompanied by a cold front that should extend from MN, eastern KS, northwest OK into the TX Panhandle by late tomorrow afternoon. A warm front will advance northward reaching northern MO early in the period. ...Middle MS Valley region through eastern Kansas and Oklahoma... Ascent with a leading vorticity maximum embedded within the amplifying upper trough will likely contribute to a few storms early in the period, mainly from eastern NE into IA. A few instances of hail and locally strong wind gusts cannot be ruled out with this activity. South of the early storms, the moistening warm sector will become strongly unstable with low to mid 70s F dewpoints beneath 7-7.5 C/km mid-level lapse rates, and diabatic warming of the boundary layer contributing to 3000-4000 J/kg MLCAPE. Wind profiles will strengthen in association with the amplifying trough with 35-45 kt effective bulk shear. Storms are expected to redevelop along the cold front, initially over northeast KS into northwest MO and move east through MO. A broken band of storms with mixed modes including supercells and line segments appears likely with large hail and damaging wind. A few tornadoes may be possible especially over northern MO where remnant boundary from early activity might augment 0-2 km storm relative helicity. Backbuilding into OK is expected as the front continues south during the evening. Though wind profiles will be weaker with southwestern extent into OK, the thermodynamic environment with strong instability and steep lapse rates will support a risk for large hail and downburst winds. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 30% - Enhanced ..Dial.. 08/25/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Aug 25 2019 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OKLAHOMA...EASTERN KANSAS INTO MISSOURI... ...SUMMARY... Severe thunderstorms are expected Monday afternoon and evening from the Middle Mississippi Valley region into eastern Kansas and Oklahoma. Large hail and damaging winds should be the main threats, though a few tornadoes are also possible. ...Synopsis... A broad low-amplitude upper trough now situated from southwestern Canada into the northern Rockies is forecast to undergo significant amplification as it moves through the northern Plains and upper MS Valley region Monday. This feature will be accompanied by a cold front that should extend from MN, eastern KS, northwest OK into the TX Panhandle by late tomorrow afternoon. A warm front will advance northward reaching northern MO early in the period. ...Middle MS Valley region through eastern Kansas and Oklahoma... Ascent with a leading vorticity maximum embedded within the amplifying upper trough will likely contribute to a few storms early in the period, mainly from eastern NE into IA. A few instances of hail and locally strong wind gusts cannot be ruled out with this activity. South of the early storms, the moistening warm sector will become strongly unstable with low to mid 70s F dewpoints beneath 7-7.5 C/km mid-level lapse rates, and diabatic warming of the boundary layer contributing to 3000-4000 J/kg MLCAPE. Wind profiles will strengthen in association with the amplifying trough with 35-45 kt effective bulk shear. Storms are expected to redevelop along the cold front, initially over northeast KS into northwest MO and move east through MO. A broken band of storms with mixed modes including supercells and line segments appears likely with large hail and damaging wind. A few tornadoes may be possible especially over northern MO where remnant boundary from early activity might augment 0-2 km storm relative helicity. Backbuilding into OK is expected as the front continues south during the evening. Though wind profiles will be weaker with southwestern extent into OK, the thermodynamic environment with strong instability and steep lapse rates will support a risk for large hail and downburst winds. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 30% - Enhanced ..Dial.. 08/25/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Sun Aug 25 2019 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM THE DAKOTAS INTO NORTHERN NE... ...SUMMARY... Thunderstorms with large hail and a few damaging gusts are expected over parts of the Dakotas this afternoon/evening into northern Nebraska overnight. ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. ..Thompson/Cook.. 08/25/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Sun Aug 25 2019 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM THE DAKOTAS INTO NORTHERN NE... ...SUMMARY... Thunderstorms with large hail and a few damaging gusts are expected over parts of the Dakotas this afternoon/evening into northern Nebraska overnight. ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. ..Thompson/Cook.. 08/25/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Sun Aug 25 2019 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM THE DAKOTAS INTO NORTHERN NE... ...SUMMARY... Thunderstorms with large hail and a few damaging gusts are expected over parts of the Dakotas this afternoon/evening into northern Nebraska overnight. ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. ..Thompson/Cook.. 08/25/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Sun Aug 25 2019 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT FROM THE DAKOTAS INTO NORTHERN NE... ...SUMMARY... Thunderstorms with large hail and a few damaging gusts are expected over parts of the Dakotas this afternoon/evening into northern Nebraska overnight. ...Dakotas to NE this afternoon into tonight... A northern stream shortwave trough will amplify over the northern High Plains through tonight. An initial surface trough/cold front across the western Dakotas will continue eastward into the eastern Dakotas and southeastward into NE by the end of the period. A narrow zone of surface heating along the surface trough and weak large-scale ascent will support thunderstorm development this afternoon/evening across the central Dakotas, and storms will subsequently spread eastward and southeastward tonight. Steep midlevel lapse rates will combine with the surface heating and boundary-layer dewpoints in the mid 60s to result in MLCAPE of 1500-2500 J/kg immediately east of the surface trough this afternoon. Deep-layer vertical shear with straight hodographs will initially favor supercells capable of producing large hail, though upscale growth into clusters/line segments with damaging winds appears probable this evening before the convection begins to spread east of the stronger buoyancy. The southern flank of the frontal convection is likely to maintain intensity the longest, potentially developing southward into NE in conjunction with the surface triple point and warm advection on the nose of 30-40 kt nocturnal low-level jet. Other more isolated storms will be possible later this evening from the Big Horns into southwestern SD, in the immediate post-frontal upslope flow regime. Deep-layer vertical shear will be favorable for supercells, though limited moisture/buoyancy should tend to temper the hail/wind threat somewhat. ...OK/AR/MO this afternoon... A convectively enhanced midlevel trough is moving eastward over eastern KS and northeastern OK as of mid morning. Vertical shear will be strongest to the west of the trough in conjunction with the stronger northwesterly midlevel flow. However, storm initiation beyond ongoing convection in the warm advection zone near I-35 along the KS/OK border is unlikely given the expected onset of subsidence in the wake of the midlevel trough. Some destabilization is expected south through east of the convective outflow, though clouds are relatively widespread and will likely continue to slow surface heating. Overall, it appears that a marginal threat for damaging wind is the primary concern with multicell clusters along the outflow boundary this afternoon from southern MO into northwestern AR and southeastern OK. ..Thompson/Cook.. 08/25/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1031 AM CDT Sun Aug 25 2019 Valid 251700Z - 261200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHEAST NEVADA...SOUTHERN IDAHO...NORTHERN UTAH...SOUTHERN WYOMING...NORTHWEST COLORADO... The critical areas were joined and minor modifications were made elsewhere based on latest guidance and observations. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0109 AM CDT Sun Aug 25 2019/ ...Synopsis... A strong mid-level jet will push into the central Rockies today, on the back side of a broad upper-level trough along the Canadian border. At the surface, a cold front will move across the Intermountain West. Boundary-layer mixing of stronger flow aloft along with a more stout surface pressure gradient than recent days will lead to critical fire weather conditions across portions of both the northern Great Basin and central Rockies. Winds of 20-25 mph will be common across the highlighted critical area. Potential for 25+ mph sustained winds, and higher gusts, will be maximized underneath the mid-level jet core in the Snake River Valley and southern Wyoming. Elevated conditions will occur surrounding the critical area as winds in these locations will either be lighter (15-20 mph) and/or fuels will be slightly less receptive to fire spread. All areas that have been highlighted can expect 10-15% RH during the afternoon. Only minor changes have been made from the previous forecast on account of the latest guidance. The critical area in northeast Nevada was expanded slightly westward and the elevated area was expanded to include more of central Colorado. ...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 1031 AM CDT Sun Aug 25 2019 Valid 251700Z - 261200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHEAST NEVADA...SOUTHERN IDAHO...NORTHERN UTAH...SOUTHERN WYOMING...NORTHWEST COLORADO... The critical areas were joined and minor modifications were made elsewhere based on latest guidance and observations. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0109 AM CDT Sun Aug 25 2019/ ...Synopsis... A strong mid-level jet will push into the central Rockies today, on the back side of a broad upper-level trough along the Canadian border. At the surface, a cold front will move across the Intermountain West. Boundary-layer mixing of stronger flow aloft along with a more stout surface pressure gradient than recent days will lead to critical fire weather conditions across portions of both the northern Great Basin and central Rockies. Winds of 20-25 mph will be common across the highlighted critical area. Potential for 25+ mph sustained winds, and higher gusts, will be maximized underneath the mid-level jet core in the Snake River Valley and southern Wyoming. Elevated conditions will occur surrounding the critical area as winds in these locations will either be lighter (15-20 mph) and/or fuels will be slightly less receptive to fire spread. All areas that have been highlighted can expect 10-15% RH during the afternoon. Only minor changes have been made from the previous forecast on account of the latest guidance. The critical area in northeast Nevada was expanded slightly westward and the elevated area was expanded to include more of central Colorado. ...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 1031 AM CDT Sun Aug 25 2019 Valid 251700Z - 261200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHEAST NEVADA...SOUTHERN IDAHO...NORTHERN UTAH...SOUTHERN WYOMING...NORTHWEST COLORADO... The critical areas were joined and minor modifications were made elsewhere based on latest guidance and observations. The forecast remains on track, and please see the discussion below for more details. ..Nauslar.. 08/25/2019 .PREV DISCUSSION... /ISSUED 0109 AM CDT Sun Aug 25 2019/ ...Synopsis... A strong mid-level jet will push into the central Rockies today, on the back side of a broad upper-level trough along the Canadian border. At the surface, a cold front will move across the Intermountain West. Boundary-layer mixing of stronger flow aloft along with a more stout surface pressure gradient than recent days will lead to critical fire weather conditions across portions of both the northern Great Basin and central Rockies. Winds of 20-25 mph will be common across the highlighted critical area. Potential for 25+ mph sustained winds, and higher gusts, will be maximized underneath the mid-level jet core in the Snake River Valley and southern Wyoming. Elevated conditions will occur surrounding the critical area as winds in these locations will either be lighter (15-20 mph) and/or fuels will be slightly less receptive to fire spread. All areas that have been highlighted can expect 10-15% RH during the afternoon. Only minor changes have been made from the previous forecast on account of the latest guidance. The critical area in northeast Nevada was expanded slightly westward and the elevated area was expanded to include more of central Colorado. ...Please see www.spc.noaa.gov/fire for graphic product... Read more