Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS EASTWARD TO THE MID-ATLANTIC... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into the Ohio and Tennessee Valleys. Other strong to severe storms are possible over the Upper Mississippi Valley and the central High Plains. ...Mid-Atlantic/Ohio and Tennessee Valleys... A subtle cyclonic mid-level flow pattern will be in place on Tuesday from the north-central states eastward into the Northeast. At the surface, a cold front will advance southward into the Mid-Atlantic extending west-southwestward into the mid Mississippi Valley. A surface low along the front will move eastward across the central Appalachians. Surface dewpoints ahead of the front should be in the lower 70s contributing to a corridor of moderate instability by afternoon. Scattered thunderstorms are forecast to develop along the front during the afternoon from southern Ohio eastward across the Virginias into Maryland. Cells may tend to organize into lines and MCS development will be possible from late afternoon into the early evening. NAM forecast soundings along the front from West Virginia into northern Virginia and southern Maryland suggest that MLCAPE values could reach 2500 J/kg at peak heating. Winds are veered to the southwest at the surface with about 30 kt of westerly flow in the mid-levels. This combined with steep lapse rates in the lowest 3 km AGL will be favorable for damaging wind gusts associated with line segments. If a cold pool can develop with a larger-scale line segment, then numerous damaging wind gusts will be possible from eastern West Virginia eastward to Delaware and southern New Jersey. ...Upper Mississippi Valley... A minor shortwave trough will move east-southeastward into the Upper Mississippi Valley on Tuesday. At the surface, a low will track southeastward from central Minnesota to near Minneapolis and then along the Mississippi River. Ahead of the surface low track, an axis of maximized low-level moisture will exist with surface dewpoints in the mid 60s F. In response to surface heating, a pocket of moderate instability may develop by afternoon. Convection is forecast to initiate ahead of the shortwave trough and move southeastward across eastern Minnesota and western Wisconsin during the mid to late afternoon. MLCAPE values in the 1000 to 2000 J/kg combined with 0-6 km shear of 35 to 45 kt may be favorable for an isolated severe threat with hail and strong gusty winds possible. Poor lapse rates should keep any threat marginal. ...Central Plains... A low-amplitude upper-level ridge will move across the western U.S. on Tuesday as west to northwest mid-level flow remains over the central High Plains. At the surface, a mesolow is forecast to develop in southeastern Colorado ahead of a front, moving southward into northeastern Colorado. Convection appears likely to initiate along the front during the late afternoon with thunderstorms moving southeastward into western Kansas by early evening. Strong directional shear profiles along with steep lapse rates may be enough for hail in the stronger cores. A few marginally severe wind gusts will also be possible. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Broyles.. 08/12/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS EASTWARD TO THE MID-ATLANTIC... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into the Ohio and Tennessee Valleys. Other strong to severe storms are possible over the Upper Mississippi Valley and the central High Plains. ...Mid-Atlantic/Ohio and Tennessee Valleys... A subtle cyclonic mid-level flow pattern will be in place on Tuesday from the north-central states eastward into the Northeast. At the surface, a cold front will advance southward into the Mid-Atlantic extending west-southwestward into the mid Mississippi Valley. A surface low along the front will move eastward across the central Appalachians. Surface dewpoints ahead of the front should be in the lower 70s contributing to a corridor of moderate instability by afternoon. Scattered thunderstorms are forecast to develop along the front during the afternoon from southern Ohio eastward across the Virginias into Maryland. Cells may tend to organize into lines and MCS development will be possible from late afternoon into the early evening. NAM forecast soundings along the front from West Virginia into northern Virginia and southern Maryland suggest that MLCAPE values could reach 2500 J/kg at peak heating. Winds are veered to the southwest at the surface with about 30 kt of westerly flow in the mid-levels. This combined with steep lapse rates in the lowest 3 km AGL will be favorable for damaging wind gusts associated with line segments. If a cold pool can develop with a larger-scale line segment, then numerous damaging wind gusts will be possible from eastern West Virginia eastward to Delaware and southern New Jersey. ...Upper Mississippi Valley... A minor shortwave trough will move east-southeastward into the Upper Mississippi Valley on Tuesday. At the surface, a low will track southeastward from central Minnesota to near Minneapolis and then along the Mississippi River. Ahead of the surface low track, an axis of maximized low-level moisture will exist with surface dewpoints in the mid 60s F. In response to surface heating, a pocket of moderate instability may develop by afternoon. Convection is forecast to initiate ahead of the shortwave trough and move southeastward across eastern Minnesota and western Wisconsin during the mid to late afternoon. MLCAPE values in the 1000 to 2000 J/kg combined with 0-6 km shear of 35 to 45 kt may be favorable for an isolated severe threat with hail and strong gusty winds possible. Poor lapse rates should keep any threat marginal. ...Central Plains... A low-amplitude upper-level ridge will move across the western U.S. on Tuesday as west to northwest mid-level flow remains over the central High Plains. At the surface, a mesolow is forecast to develop in southeastern Colorado ahead of a front, moving southward into northeastern Colorado. Convection appears likely to initiate along the front during the late afternoon with thunderstorms moving southeastward into western Kansas by early evening. Strong directional shear profiles along with steep lapse rates may be enough for hail in the stronger cores. A few marginally severe wind gusts will also be possible. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Broyles.. 08/12/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS EASTWARD TO THE MID-ATLANTIC... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into the Ohio and Tennessee Valleys. Other strong to severe storms are possible over the Upper Mississippi Valley and the central High Plains. ...Mid-Atlantic/Ohio and Tennessee Valleys... A subtle cyclonic mid-level flow pattern will be in place on Tuesday from the north-central states eastward into the Northeast. At the surface, a cold front will advance southward into the Mid-Atlantic extending west-southwestward into the mid Mississippi Valley. A surface low along the front will move eastward across the central Appalachians. Surface dewpoints ahead of the front should be in the lower 70s contributing to a corridor of moderate instability by afternoon. Scattered thunderstorms are forecast to develop along the front during the afternoon from southern Ohio eastward across the Virginias into Maryland. Cells may tend to organize into lines and MCS development will be possible from late afternoon into the early evening. NAM forecast soundings along the front from West Virginia into northern Virginia and southern Maryland suggest that MLCAPE values could reach 2500 J/kg at peak heating. Winds are veered to the southwest at the surface with about 30 kt of westerly flow in the mid-levels. This combined with steep lapse rates in the lowest 3 km AGL will be favorable for damaging wind gusts associated with line segments. If a cold pool can develop with a larger-scale line segment, then numerous damaging wind gusts will be possible from eastern West Virginia eastward to Delaware and southern New Jersey. ...Upper Mississippi Valley... A minor shortwave trough will move east-southeastward into the Upper Mississippi Valley on Tuesday. At the surface, a low will track southeastward from central Minnesota to near Minneapolis and then along the Mississippi River. Ahead of the surface low track, an axis of maximized low-level moisture will exist with surface dewpoints in the mid 60s F. In response to surface heating, a pocket of moderate instability may develop by afternoon. Convection is forecast to initiate ahead of the shortwave trough and move southeastward across eastern Minnesota and western Wisconsin during the mid to late afternoon. MLCAPE values in the 1000 to 2000 J/kg combined with 0-6 km shear of 35 to 45 kt may be favorable for an isolated severe threat with hail and strong gusty winds possible. Poor lapse rates should keep any threat marginal. ...Central Plains... A low-amplitude upper-level ridge will move across the western U.S. on Tuesday as west to northwest mid-level flow remains over the central High Plains. At the surface, a mesolow is forecast to develop in southeastern Colorado ahead of a front, moving southward into northeastern Colorado. Convection appears likely to initiate along the front during the late afternoon with thunderstorms moving southeastward into western Kansas by early evening. Strong directional shear profiles along with steep lapse rates may be enough for hail in the stronger cores. A few marginally severe wind gusts will also be possible. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Broyles.. 08/12/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL APPALACHIANS EASTWARD TO THE MID-ATLANTIC... ...SUMMARY... Severe storms are expected Tuesday afternoon and early evening over the Middle Atlantic into the Ohio and Tennessee Valleys. Other strong to severe storms are possible over the Upper Mississippi Valley and the central High Plains. ...Mid-Atlantic/Ohio and Tennessee Valleys... A subtle cyclonic mid-level flow pattern will be in place on Tuesday from the north-central states eastward into the Northeast. At the surface, a cold front will advance southward into the Mid-Atlantic extending west-southwestward into the mid Mississippi Valley. A surface low along the front will move eastward across the central Appalachians. Surface dewpoints ahead of the front should be in the lower 70s contributing to a corridor of moderate instability by afternoon. Scattered thunderstorms are forecast to develop along the front during the afternoon from southern Ohio eastward across the Virginias into Maryland. Cells may tend to organize into lines and MCS development will be possible from late afternoon into the early evening. NAM forecast soundings along the front from West Virginia into northern Virginia and southern Maryland suggest that MLCAPE values could reach 2500 J/kg at peak heating. Winds are veered to the southwest at the surface with about 30 kt of westerly flow in the mid-levels. This combined with steep lapse rates in the lowest 3 km AGL will be favorable for damaging wind gusts associated with line segments. If a cold pool can develop with a larger-scale line segment, then numerous damaging wind gusts will be possible from eastern West Virginia eastward to Delaware and southern New Jersey. ...Upper Mississippi Valley... A minor shortwave trough will move east-southeastward into the Upper Mississippi Valley on Tuesday. At the surface, a low will track southeastward from central Minnesota to near Minneapolis and then along the Mississippi River. Ahead of the surface low track, an axis of maximized low-level moisture will exist with surface dewpoints in the mid 60s F. In response to surface heating, a pocket of moderate instability may develop by afternoon. Convection is forecast to initiate ahead of the shortwave trough and move southeastward across eastern Minnesota and western Wisconsin during the mid to late afternoon. MLCAPE values in the 1000 to 2000 J/kg combined with 0-6 km shear of 35 to 45 kt may be favorable for an isolated severe threat with hail and strong gusty winds possible. Poor lapse rates should keep any threat marginal. ...Central Plains... A low-amplitude upper-level ridge will move across the western U.S. on Tuesday as west to northwest mid-level flow remains over the central High Plains. At the surface, a mesolow is forecast to develop in southeastern Colorado ahead of a front, moving southward into northeastern Colorado. Convection appears likely to initiate along the front during the late afternoon with thunderstorms moving southeastward into western Kansas by early evening. Strong directional shear profiles along with steep lapse rates may be enough for hail in the stronger cores. A few marginally severe wind gusts will also be possible. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 30% - Enhanced Hail: 15% - Slight ..Broyles.. 08/12/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 12 2019 Valid 121630Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST IA TO WEST-CENTRAL IN... ...SUMMARY... A few tornadoes, a couple possibly strong, and significant damaging winds will be likely across southeast Iowa through central Illinois, mainly this evening. ...IA/IL/IN... An upgrade to Moderate Risk for tornado and/or wind may become necessary in later outlooks today. A leading MCV is tracking east into eastern IA with a lingering surface cyclone centered over west-central IA. This latter feature should move east into northern IL through this evening. Diffuse convective outflow from remnant leading MCS over southern IL has been shunted across southeast to northwest MO. Nevertheless, air mass recovery is underway north of the boundary into extreme southern IA and west-central IL. Further erosion of the prior cold pool amid cloud breaks should yield at least weak to moderate surface-based buoyancy by late afternoon in IA to northern IL. More robust destabilization is expected farther south where greater unimpeded insolation occurs while a plume of 77-81 F surface dew points is advected north from the Mid-South. Despite relatively warm mid-level temperatures, the very rich boundary-layer moisture and surface heating should yield a plume of large buoyancy with MLCAPE likely reaching 3000-4000 J/kg across much of MO into central/southern IL. Renewed thunderstorm development is probable towards late afternoon near the surface cyclone in southeast IA and during the early evening to the southeast in central IL within a corridor of strengthening low-level warm advection. The initial storms will likely be supercells capable of producing all hazards, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front. Hodographs aloft should tend to favor relatively quick upscale growth, but even semi-discrete supercells will pose a risk for at least a few tornadoes, a couple of which be may strong. A forward-propagating MCS should eventually evolve along the MLCAPE gradient from central IL into central IN where severe wind gusts will remain a threat before weakening overnight. ...TX Panhandle to southern KS/northern OK... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...ME... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts and marginally severe hail. ...Dakotas... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Grams/Dean.. 08/12/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 12 2019 Valid 121630Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST IA TO WEST-CENTRAL IN... ...SUMMARY... A few tornadoes, a couple possibly strong, and significant damaging winds will be likely across southeast Iowa through central Illinois, mainly this evening. ...IA/IL/IN... An upgrade to Moderate Risk for tornado and/or wind may become necessary in later outlooks today. A leading MCV is tracking east into eastern IA with a lingering surface cyclone centered over west-central IA. This latter feature should move east into northern IL through this evening. Diffuse convective outflow from remnant leading MCS over southern IL has been shunted across southeast to northwest MO. Nevertheless, air mass recovery is underway north of the boundary into extreme southern IA and west-central IL. Further erosion of the prior cold pool amid cloud breaks should yield at least weak to moderate surface-based buoyancy by late afternoon in IA to northern IL. More robust destabilization is expected farther south where greater unimpeded insolation occurs while a plume of 77-81 F surface dew points is advected north from the Mid-South. Despite relatively warm mid-level temperatures, the very rich boundary-layer moisture and surface heating should yield a plume of large buoyancy with MLCAPE likely reaching 3000-4000 J/kg across much of MO into central/southern IL. Renewed thunderstorm development is probable towards late afternoon near the surface cyclone in southeast IA and during the early evening to the southeast in central IL within a corridor of strengthening low-level warm advection. The initial storms will likely be supercells capable of producing all hazards, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front. Hodographs aloft should tend to favor relatively quick upscale growth, but even semi-discrete supercells will pose a risk for at least a few tornadoes, a couple of which be may strong. A forward-propagating MCS should eventually evolve along the MLCAPE gradient from central IL into central IN where severe wind gusts will remain a threat before weakening overnight. ...TX Panhandle to southern KS/northern OK... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...ME... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts and marginally severe hail. ...Dakotas... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Grams/Dean.. 08/12/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 12 2019 Valid 121630Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST IA TO WEST-CENTRAL IN... ...SUMMARY... A few tornadoes, a couple possibly strong, and significant damaging winds will be likely across southeast Iowa through central Illinois, mainly this evening. ...IA/IL/IN... An upgrade to Moderate Risk for tornado and/or wind may become necessary in later outlooks today. A leading MCV is tracking east into eastern IA with a lingering surface cyclone centered over west-central IA. This latter feature should move east into northern IL through this evening. Diffuse convective outflow from remnant leading MCS over southern IL has been shunted across southeast to northwest MO. Nevertheless, air mass recovery is underway north of the boundary into extreme southern IA and west-central IL. Further erosion of the prior cold pool amid cloud breaks should yield at least weak to moderate surface-based buoyancy by late afternoon in IA to northern IL. More robust destabilization is expected farther south where greater unimpeded insolation occurs while a plume of 77-81 F surface dew points is advected north from the Mid-South. Despite relatively warm mid-level temperatures, the very rich boundary-layer moisture and surface heating should yield a plume of large buoyancy with MLCAPE likely reaching 3000-4000 J/kg across much of MO into central/southern IL. Renewed thunderstorm development is probable towards late afternoon near the surface cyclone in southeast IA and during the early evening to the southeast in central IL within a corridor of strengthening low-level warm advection. The initial storms will likely be supercells capable of producing all hazards, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front. Hodographs aloft should tend to favor relatively quick upscale growth, but even semi-discrete supercells will pose a risk for at least a few tornadoes, a couple of which be may strong. A forward-propagating MCS should eventually evolve along the MLCAPE gradient from central IL into central IN where severe wind gusts will remain a threat before weakening overnight. ...TX Panhandle to southern KS/northern OK... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...ME... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts and marginally severe hail. ...Dakotas... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Grams/Dean.. 08/12/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 12 2019 Valid 121630Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST IA TO WEST-CENTRAL IN... ...SUMMARY... A few tornadoes, a couple possibly strong, and significant damaging winds will be likely across southeast Iowa through central Illinois, mainly this evening. ...IA/IL/IN... An upgrade to Moderate Risk for tornado and/or wind may become necessary in later outlooks today. A leading MCV is tracking east into eastern IA with a lingering surface cyclone centered over west-central IA. This latter feature should move east into northern IL through this evening. Diffuse convective outflow from remnant leading MCS over southern IL has been shunted across southeast to northwest MO. Nevertheless, air mass recovery is underway north of the boundary into extreme southern IA and west-central IL. Further erosion of the prior cold pool amid cloud breaks should yield at least weak to moderate surface-based buoyancy by late afternoon in IA to northern IL. More robust destabilization is expected farther south where greater unimpeded insolation occurs while a plume of 77-81 F surface dew points is advected north from the Mid-South. Despite relatively warm mid-level temperatures, the very rich boundary-layer moisture and surface heating should yield a plume of large buoyancy with MLCAPE likely reaching 3000-4000 J/kg across much of MO into central/southern IL. Renewed thunderstorm development is probable towards late afternoon near the surface cyclone in southeast IA and during the early evening to the southeast in central IL within a corridor of strengthening low-level warm advection. The initial storms will likely be supercells capable of producing all hazards, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front. Hodographs aloft should tend to favor relatively quick upscale growth, but even semi-discrete supercells will pose a risk for at least a few tornadoes, a couple of which be may strong. A forward-propagating MCS should eventually evolve along the MLCAPE gradient from central IL into central IN where severe wind gusts will remain a threat before weakening overnight. ...TX Panhandle to southern KS/northern OK... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...ME... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts and marginally severe hail. ...Dakotas... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Grams/Dean.. 08/12/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 12 2019 Valid 121630Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST IA TO WEST-CENTRAL IN... ...SUMMARY... A few tornadoes, a couple possibly strong, and significant damaging winds will be likely across southeast Iowa through central Illinois, mainly this evening. ...IA/IL/IN... An upgrade to Moderate Risk for tornado and/or wind may become necessary in later outlooks today. A leading MCV is tracking east into eastern IA with a lingering surface cyclone centered over west-central IA. This latter feature should move east into northern IL through this evening. Diffuse convective outflow from remnant leading MCS over southern IL has been shunted across southeast to northwest MO. Nevertheless, air mass recovery is underway north of the boundary into extreme southern IA and west-central IL. Further erosion of the prior cold pool amid cloud breaks should yield at least weak to moderate surface-based buoyancy by late afternoon in IA to northern IL. More robust destabilization is expected farther south where greater unimpeded insolation occurs while a plume of 77-81 F surface dew points is advected north from the Mid-South. Despite relatively warm mid-level temperatures, the very rich boundary-layer moisture and surface heating should yield a plume of large buoyancy with MLCAPE likely reaching 3000-4000 J/kg across much of MO into central/southern IL. Renewed thunderstorm development is probable towards late afternoon near the surface cyclone in southeast IA and during the early evening to the southeast in central IL within a corridor of strengthening low-level warm advection. The initial storms will likely be supercells capable of producing all hazards, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front. Hodographs aloft should tend to favor relatively quick upscale growth, but even semi-discrete supercells will pose a risk for at least a few tornadoes, a couple of which be may strong. A forward-propagating MCS should eventually evolve along the MLCAPE gradient from central IL into central IN where severe wind gusts will remain a threat before weakening overnight. ...TX Panhandle to southern KS/northern OK... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...ME... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts and marginally severe hail. ...Dakotas... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Grams/Dean.. 08/12/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1114 AM CDT Mon Aug 12 2019 Valid 121700Z - 131200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes made. Please see below for details. ..Squitieri.. 08/12/2019 .PREV DISCUSSION... /ISSUED 0712 AM CDT Mon Aug 12 2019/ ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ...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 1114 AM CDT Mon Aug 12 2019 Valid 121700Z - 131200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes made. Please see below for details. ..Squitieri.. 08/12/2019 .PREV DISCUSSION... /ISSUED 0712 AM CDT Mon Aug 12 2019/ ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ...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 1114 AM CDT Mon Aug 12 2019 Valid 121700Z - 131200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes made. Please see below for details. ..Squitieri.. 08/12/2019 .PREV DISCUSSION... /ISSUED 0712 AM CDT Mon Aug 12 2019/ ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ...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 1114 AM CDT Mon Aug 12 2019 Valid 121700Z - 131200Z ...NO CRITICAL AREAS... The previous forecast remains on track, with no changes made. Please see below for details. ..Squitieri.. 08/12/2019 .PREV DISCUSSION... /ISSUED 0712 AM CDT Mon Aug 12 2019/ ...Synopsis... Fire weather concerns will be minimal today. A mid-level trough over the northern Rockies will weaken and eject, leaving behind weaker and more zonally oriented mid-level flow across the CONUS. Mid-level flow will become minimal across dry areas of the western U.S. Outside of areas of locally elevated fire weather in Wyoming and vicinity, the quiet overall pattern indicates that no highlights will be needed for this outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 AM CDT Mon Aug 12 2019 Valid 121300Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM SOUTHEAST IA INTO CENTRAL IL... ...SUMMARY... Severe thunderstorms are likely today over the middle Mississippi Valley to the Ohio Valley. Damaging gusts are the primary risk but a few tornadoes are possible. ...IA/IL this afternoon/evening... A well-defined MCV is moving eastward over western IA this morning, per reflectivity mosaics and VWP observations of 50-60 kt midlevel flow at OAX/DMX. The associated MCS and low-level cold pool have weakened since 09z, though convective outflow appears to extend farther south into KS/MO than most model guidance. Thus, recovery of the boundary layer into IA is a primary concern for this afternoon. Assuming surface heating in cloud breaks by early-mid afternoon and erosion of the morning cold pool, boundary-layer dewpoints in the low-mid 70s will contribute to MLCAPE in excess of 2000 J/kg east of the surface low and south of the warm front in IA. Renewed thunderstorm development is probable by mid afternoon near the surface low, with storms expected to subsequently move/develop east-southeastward along the warm front into IL by this evening. The initial storms will likely be supercells capable of producing tornadoes and damaging winds, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front, along the north edge of the unstable warm sector. Upscale growth into a cluster is expected by this evening from southeast IA/northeast MO into northwest and central IL, where damaging winds will become the more prominent threat into tonight. The MCV/cyclone will begin to move east of the surface warm sector late tonight, which should result in gradual weakening of the storms across IN. The northward extent and magnitude of the severe/tornado threat this afternoon will depend heavily on the degree of recovery from the ongoing/weakening MCS, which is still a bit uncertain. ...TX Panhandle this afternoon to southeast KS tonight... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle today, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...Maine this afternoon... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts. ...Dakotas this afternoon/evening... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Thompson/Kerr.. 08/12/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 AM CDT Mon Aug 12 2019 Valid 121300Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM SOUTHEAST IA INTO CENTRAL IL... ...SUMMARY... Severe thunderstorms are likely today over the middle Mississippi Valley to the Ohio Valley. Damaging gusts are the primary risk but a few tornadoes are possible. ...IA/IL this afternoon/evening... A well-defined MCV is moving eastward over western IA this morning, per reflectivity mosaics and VWP observations of 50-60 kt midlevel flow at OAX/DMX. The associated MCS and low-level cold pool have weakened since 09z, though convective outflow appears to extend farther south into KS/MO than most model guidance. Thus, recovery of the boundary layer into IA is a primary concern for this afternoon. Assuming surface heating in cloud breaks by early-mid afternoon and erosion of the morning cold pool, boundary-layer dewpoints in the low-mid 70s will contribute to MLCAPE in excess of 2000 J/kg east of the surface low and south of the warm front in IA. Renewed thunderstorm development is probable by mid afternoon near the surface low, with storms expected to subsequently move/develop east-southeastward along the warm front into IL by this evening. The initial storms will likely be supercells capable of producing tornadoes and damaging winds, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front, along the north edge of the unstable warm sector. Upscale growth into a cluster is expected by this evening from southeast IA/northeast MO into northwest and central IL, where damaging winds will become the more prominent threat into tonight. The MCV/cyclone will begin to move east of the surface warm sector late tonight, which should result in gradual weakening of the storms across IN. The northward extent and magnitude of the severe/tornado threat this afternoon will depend heavily on the degree of recovery from the ongoing/weakening MCS, which is still a bit uncertain. ...TX Panhandle this afternoon to southeast KS tonight... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle today, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...Maine this afternoon... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts. ...Dakotas this afternoon/evening... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Thompson/Kerr.. 08/12/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 AM CDT Mon Aug 12 2019 Valid 121300Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM SOUTHEAST IA INTO CENTRAL IL... ...SUMMARY... Severe thunderstorms are likely today over the middle Mississippi Valley to the Ohio Valley. Damaging gusts are the primary risk but a few tornadoes are possible. ...IA/IL this afternoon/evening... A well-defined MCV is moving eastward over western IA this morning, per reflectivity mosaics and VWP observations of 50-60 kt midlevel flow at OAX/DMX. The associated MCS and low-level cold pool have weakened since 09z, though convective outflow appears to extend farther south into KS/MO than most model guidance. Thus, recovery of the boundary layer into IA is a primary concern for this afternoon. Assuming surface heating in cloud breaks by early-mid afternoon and erosion of the morning cold pool, boundary-layer dewpoints in the low-mid 70s will contribute to MLCAPE in excess of 2000 J/kg east of the surface low and south of the warm front in IA. Renewed thunderstorm development is probable by mid afternoon near the surface low, with storms expected to subsequently move/develop east-southeastward along the warm front into IL by this evening. The initial storms will likely be supercells capable of producing tornadoes and damaging winds, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front, along the north edge of the unstable warm sector. Upscale growth into a cluster is expected by this evening from southeast IA/northeast MO into northwest and central IL, where damaging winds will become the more prominent threat into tonight. The MCV/cyclone will begin to move east of the surface warm sector late tonight, which should result in gradual weakening of the storms across IN. The northward extent and magnitude of the severe/tornado threat this afternoon will depend heavily on the degree of recovery from the ongoing/weakening MCS, which is still a bit uncertain. ...TX Panhandle this afternoon to southeast KS tonight... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle today, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...Maine this afternoon... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts. ...Dakotas this afternoon/evening... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Thompson/Kerr.. 08/12/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 AM CDT Mon Aug 12 2019 Valid 121300Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM SOUTHEAST IA INTO CENTRAL IL... ...SUMMARY... Severe thunderstorms are likely today over the middle Mississippi Valley to the Ohio Valley. Damaging gusts are the primary risk but a few tornadoes are possible. ...IA/IL this afternoon/evening... A well-defined MCV is moving eastward over western IA this morning, per reflectivity mosaics and VWP observations of 50-60 kt midlevel flow at OAX/DMX. The associated MCS and low-level cold pool have weakened since 09z, though convective outflow appears to extend farther south into KS/MO than most model guidance. Thus, recovery of the boundary layer into IA is a primary concern for this afternoon. Assuming surface heating in cloud breaks by early-mid afternoon and erosion of the morning cold pool, boundary-layer dewpoints in the low-mid 70s will contribute to MLCAPE in excess of 2000 J/kg east of the surface low and south of the warm front in IA. Renewed thunderstorm development is probable by mid afternoon near the surface low, with storms expected to subsequently move/develop east-southeastward along the warm front into IL by this evening. The initial storms will likely be supercells capable of producing tornadoes and damaging winds, given the enhanced low-level shear/hodograph curvature near the cyclone/warm front, along the north edge of the unstable warm sector. Upscale growth into a cluster is expected by this evening from southeast IA/northeast MO into northwest and central IL, where damaging winds will become the more prominent threat into tonight. The MCV/cyclone will begin to move east of the surface warm sector late tonight, which should result in gradual weakening of the storms across IN. The northward extent and magnitude of the severe/tornado threat this afternoon will depend heavily on the degree of recovery from the ongoing/weakening MCS, which is still a bit uncertain. ...TX Panhandle this afternoon to southeast KS tonight... A remnant midlevel trough will drift slowly east-northeastward over the TX Panhandle today, as a weak cold front moves slowly southeastward from KS/CO. Surface heating and deep mixing will result in inverted-v profiles along and south of the front, and will support the potential for isolated strong downburst winds. Convection will tend to develop east-northeastward tonight along the front, with strong downdrafts still possible in an environment of lingering large CAPE/DCAPE. ...Maine this afternoon... A midlevel trough over James Bay will pivot east-southeastward to Maine overnight. In advance of this trough, a weak pre-frontal trough at the surface and band of weak ascent will provide a focus for thunderstorm development this afternoon. Though moisture and lapse rates will be modest, increasing deep-layer westerly shear and surface heating on the south edge of the thicker clouds could support storms capable of producing isolated damaging gusts. ...Dakotas this afternoon/evening... Widespread clouds and rain are spreading slowly eastward across the eastern Dakotas in association with a couple of diffuse MCVs from overnight convection. A little clearing of clouds and surface heating will be possible from west to east this afternoon, in advance of a larger-scale trough moving east-southeastward from MT to ND. Isolated thunderstorm development and a low-end severe threat will be possible this afternoon if sufficient near-surface destabilization occurs, given enough vertical shear for organized storms. ..Thompson/Kerr.. 08/12/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0712 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... Weak, quasi-zonal mid-level flow will continue across the northern tier of the CONUS D2/Tuesday. Flow at the surface and aloft will be minimal across dry areas of the West outside of localized, terrain-favored areas. With the lack of major synoptic features traversing the West, fire weather conditions will be minimal. No highlights will be introduced for this outlook. ..Cook.. 08/12/2019 ...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 0712 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... Weak, quasi-zonal mid-level flow will continue across the northern tier of the CONUS D2/Tuesday. Flow at the surface and aloft will be minimal across dry areas of the West outside of localized, terrain-favored areas. With the lack of major synoptic features traversing the West, fire weather conditions will be minimal. No highlights will be introduced for this outlook. ..Cook.. 08/12/2019 ...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 0712 AM CDT Mon Aug 12 2019 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... Weak, quasi-zonal mid-level flow will continue across the northern tier of the CONUS D2/Tuesday. Flow at the surface and aloft will be minimal across dry areas of the West outside of localized, terrain-favored areas. With the lack of major synoptic features traversing the West, fire weather conditions will be minimal. No highlights will be introduced for this outlook. ..Cook.. 08/12/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more