Severe Storms

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL NORTH DAKOTA SOUTHEASTWARD ACROSS MINNESOTA AND INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest Monday and Monday night. ...Upper Midwest... An intensifying mid-level shortwave trough will move quickly from the southern Canadian Rockies east-southeastward to the Red River during the period. In the low levels, a warm front will advance northeastward through parts of the Dakotas and southern MN and a cold front will sweep eastward across the Dakotas during the latter half of the period. A cluster of showers/thunderstorms is possible during the morning associated with warm advection over the mid Missouri Valley. As forcing for ascent increases during the afternoon, storm development will become likely in areas initially farther northwest near a surface low forecast to develop east near the international border. A very unstable airmass is progged by models by late afternoon over the warm sector (3000+ J/kg MLCAPE) with strong effective shear. Details concerning the convective evolution of a cluster of storms evolving into a possible bow are unclear at this time. If confidence increases in later outlook updates, a significant-wind highlight may be included, in addition to higher wind probabilities. Upscale growth is likely by the evening into the overnight with storms moving southeast in the vicinity of the warm front into southeast MN/WI late. ...Southern New England vicinity... A mid-level trough initially extending from James Bay southward into the southern Appalachians will move east and deamplify and eventually reach the New England coast by daybreak Tuesday. A belt of moderate southwesterly flow moving through the base of the trough will encompass the Northeast into northern portions of the Mid-Atlantic states. Widespread clouds and scattered showers/thunderstorms are forecast to be ongoing Monday morning over the Adirondacks and northern New England. This area of convection and related cloud debris is forecast to move east during the day. Forecast models indicate a possibility for pockets of diurnal heating over southern New England with stronger heating/destabilization forecast farther south across PA/NJ. With at least weak destabilization forecast (250-500 J/kg MLCAPE) across southern New England and shear supportive of some storm organization, the favorable timing of peak heating will support storm intensification primarily during the 2pm-8pm EDT period. As a result, included a relatively confined area of 5-percent severe probabilities (due to wind) across southern New England extending into portions of PA/NJ. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Smith.. 09/01/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL NORTH DAKOTA SOUTHEASTWARD ACROSS MINNESOTA AND INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest Monday and Monday night. ...Upper Midwest... An intensifying mid-level shortwave trough will move quickly from the southern Canadian Rockies east-southeastward to the Red River during the period. In the low levels, a warm front will advance northeastward through parts of the Dakotas and southern MN and a cold front will sweep eastward across the Dakotas during the latter half of the period. A cluster of showers/thunderstorms is possible during the morning associated with warm advection over the mid Missouri Valley. As forcing for ascent increases during the afternoon, storm development will become likely in areas initially farther northwest near a surface low forecast to develop east near the international border. A very unstable airmass is progged by models by late afternoon over the warm sector (3000+ J/kg MLCAPE) with strong effective shear. Details concerning the convective evolution of a cluster of storms evolving into a possible bow are unclear at this time. If confidence increases in later outlook updates, a significant-wind highlight may be included, in addition to higher wind probabilities. Upscale growth is likely by the evening into the overnight with storms moving southeast in the vicinity of the warm front into southeast MN/WI late. ...Southern New England vicinity... A mid-level trough initially extending from James Bay southward into the southern Appalachians will move east and deamplify and eventually reach the New England coast by daybreak Tuesday. A belt of moderate southwesterly flow moving through the base of the trough will encompass the Northeast into northern portions of the Mid-Atlantic states. Widespread clouds and scattered showers/thunderstorms are forecast to be ongoing Monday morning over the Adirondacks and northern New England. This area of convection and related cloud debris is forecast to move east during the day. Forecast models indicate a possibility for pockets of diurnal heating over southern New England with stronger heating/destabilization forecast farther south across PA/NJ. With at least weak destabilization forecast (250-500 J/kg MLCAPE) across southern New England and shear supportive of some storm organization, the favorable timing of peak heating will support storm intensification primarily during the 2pm-8pm EDT period. As a result, included a relatively confined area of 5-percent severe probabilities (due to wind) across southern New England extending into portions of PA/NJ. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Smith.. 09/01/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL NORTH DAKOTA SOUTHEASTWARD ACROSS MINNESOTA AND INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected across portions of the Upper Midwest Monday and Monday night. ...Upper Midwest... An intensifying mid-level shortwave trough will move quickly from the southern Canadian Rockies east-southeastward to the Red River during the period. In the low levels, a warm front will advance northeastward through parts of the Dakotas and southern MN and a cold front will sweep eastward across the Dakotas during the latter half of the period. A cluster of showers/thunderstorms is possible during the morning associated with warm advection over the mid Missouri Valley. As forcing for ascent increases during the afternoon, storm development will become likely in areas initially farther northwest near a surface low forecast to develop east near the international border. A very unstable airmass is progged by models by late afternoon over the warm sector (3000+ J/kg MLCAPE) with strong effective shear. Details concerning the convective evolution of a cluster of storms evolving into a possible bow are unclear at this time. If confidence increases in later outlook updates, a significant-wind highlight may be included, in addition to higher wind probabilities. Upscale growth is likely by the evening into the overnight with storms moving southeast in the vicinity of the warm front into southeast MN/WI late. ...Southern New England vicinity... A mid-level trough initially extending from James Bay southward into the southern Appalachians will move east and deamplify and eventually reach the New England coast by daybreak Tuesday. A belt of moderate southwesterly flow moving through the base of the trough will encompass the Northeast into northern portions of the Mid-Atlantic states. Widespread clouds and scattered showers/thunderstorms are forecast to be ongoing Monday morning over the Adirondacks and northern New England. This area of convection and related cloud debris is forecast to move east during the day. Forecast models indicate a possibility for pockets of diurnal heating over southern New England with stronger heating/destabilization forecast farther south across PA/NJ. With at least weak destabilization forecast (250-500 J/kg MLCAPE) across southern New England and shear supportive of some storm organization, the favorable timing of peak heating will support storm intensification primarily during the 2pm-8pm EDT period. As a result, included a relatively confined area of 5-percent severe probabilities (due to wind) across southern New England extending into portions of PA/NJ. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% - Slight ..Smith.. 09/01/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OH VALLEY...NORTHERN/CENTRAL PLAINS...AND SOUTHERN/CENTRAL AZ... ...SUMMARY... Isolated severe storms may occur mainly this afternoon across parts of the Ohio Valley, this evening/tonight across portions of the northern/central Plains, and this afternoon/evening over parts of southern/central Arizona. ...Ohio Valley... Within broadly cyclonic flow over eastern Canada and the Great Lakes, a weak shortwave trough will move across parts of the OH Valley today. Modest ascent associated with this feature should encourage at least scattered storm development by the afternoon from eastern IN into northern KY and OH. This convection should then spread eastward across parts of WV into western PA through the early evening. Even though mid-level lapse rates will remain modest, diurnal heating will contribute to around 1000-2000 J/kg of MLCAPE across most of this region by this afternoon. A veering wind profile in low levels combined with around 20-30 kt of mid-level west-southwesterly flow may support occasional storm organization. Small multicells/clusters capable of producing isolated strong to damaging winds appear to be the main threat. This risk should quickly diminish with eastward extent into PA by late evening as instability wanes. ...Northern/Central Plains... Upper ridging will remain prominent across much of the northern/central Plains through the period. An upper trough/low over BC will move eastward into AB and gradually erode the upper ridge over the northern Rockies and vicinity late tonight. At the surface, a low will develop eastward across central/eastern MT from this evening through early Monday morning. An EML with steep mid-level lapse rates will gradually overspread much of the northern/central Plains though tonight. Greater low-level moisture will likely remain confined along/south of a surface boundary that will be located near the SD/NE border through this evening. Considerable uncertainty remains regarding possible convective initiation during the day, as subsidence associated with the upper ridge will probably tend to limit overall storm coverage across the northern/central Plains. A southerly low-level jet should strengthen to around 30-40 kt across western KS into central NE in the 00-06Z time frame. Warm air advection and related lift may support at least isolated storm development this evening across parts of western/central NE and vicinity. Although any storms that develop will probably be slightly elevated, steep mid-level lapse rates and rich low-level moisture will result in strong MUCAPE across this area, potentially in excess of 3000 J/kg. Around 35-45 kt of effective bulk shear will likely promote rotating updrafts with these storms, and isolated large hail may occur with any elevated supercells that form initially. Farther north, a strengthening south-southwesterly low-level jet late in the period (06-12Z) may encourage isolated convection to develop over northeastern MT/southern SK and subsequently spread southeastward along an instability gradient into parts of western/central ND early Monday morning. Overall coverage still remains uncertain, but there appears to be enough of a convective precipitation signal in short-term guidance to support inclusion of 5% probabilities for isolated instances of large hail occurring with elevated strong to severe storms given the strong shear that will be present. ...Southern/Central Arizona... An upper high will remain centered over the Four Corners region today. Orographic lift should be the main driver of isolated to widely scattered convection that should develop by early afternoon across the higher terrain of western NM and southern/central AZ. However, unlike the past couple of days, around 20 kt of easterly flow at 500 mb may prove sufficient to move these storms off the higher terrain and into lower elevations of southern/central AZ through the evening. A deeply mixed boundary layer is expected to be in place across this area, which will encourage strong/gusty downdraft winds potentially producing isolated damage. Marginally severe hail may also occur with more discrete initial development. These storms should move westward through the evening posing mainly a wind threat before eventually weakening as convective inhibition slowly increases. ...Florida... Strong low-level shear and outer rain bands associated with Hurricane Dorian are forecast to remain generally offshore and to the east of the southern/central FL Peninsula through the period. See the latest advisories from the National Hurricane Center for more information on other hazards associated with Hurricane Dorian. ..Gleason/Squitieri.. 09/01/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OH VALLEY...NORTHERN/CENTRAL PLAINS...AND SOUTHERN/CENTRAL AZ... ...SUMMARY... Isolated severe storms may occur mainly this afternoon across parts of the Ohio Valley, this evening/tonight across portions of the northern/central Plains, and this afternoon/evening over parts of southern/central Arizona. ...Ohio Valley... Within broadly cyclonic flow over eastern Canada and the Great Lakes, a weak shortwave trough will move across parts of the OH Valley today. Modest ascent associated with this feature should encourage at least scattered storm development by the afternoon from eastern IN into northern KY and OH. This convection should then spread eastward across parts of WV into western PA through the early evening. Even though mid-level lapse rates will remain modest, diurnal heating will contribute to around 1000-2000 J/kg of MLCAPE across most of this region by this afternoon. A veering wind profile in low levels combined with around 20-30 kt of mid-level west-southwesterly flow may support occasional storm organization. Small multicells/clusters capable of producing isolated strong to damaging winds appear to be the main threat. This risk should quickly diminish with eastward extent into PA by late evening as instability wanes. ...Northern/Central Plains... Upper ridging will remain prominent across much of the northern/central Plains through the period. An upper trough/low over BC will move eastward into AB and gradually erode the upper ridge over the northern Rockies and vicinity late tonight. At the surface, a low will develop eastward across central/eastern MT from this evening through early Monday morning. An EML with steep mid-level lapse rates will gradually overspread much of the northern/central Plains though tonight. Greater low-level moisture will likely remain confined along/south of a surface boundary that will be located near the SD/NE border through this evening. Considerable uncertainty remains regarding possible convective initiation during the day, as subsidence associated with the upper ridge will probably tend to limit overall storm coverage across the northern/central Plains. A southerly low-level jet should strengthen to around 30-40 kt across western KS into central NE in the 00-06Z time frame. Warm air advection and related lift may support at least isolated storm development this evening across parts of western/central NE and vicinity. Although any storms that develop will probably be slightly elevated, steep mid-level lapse rates and rich low-level moisture will result in strong MUCAPE across this area, potentially in excess of 3000 J/kg. Around 35-45 kt of effective bulk shear will likely promote rotating updrafts with these storms, and isolated large hail may occur with any elevated supercells that form initially. Farther north, a strengthening south-southwesterly low-level jet late in the period (06-12Z) may encourage isolated convection to develop over northeastern MT/southern SK and subsequently spread southeastward along an instability gradient into parts of western/central ND early Monday morning. Overall coverage still remains uncertain, but there appears to be enough of a convective precipitation signal in short-term guidance to support inclusion of 5% probabilities for isolated instances of large hail occurring with elevated strong to severe storms given the strong shear that will be present. ...Southern/Central Arizona... An upper high will remain centered over the Four Corners region today. Orographic lift should be the main driver of isolated to widely scattered convection that should develop by early afternoon across the higher terrain of western NM and southern/central AZ. However, unlike the past couple of days, around 20 kt of easterly flow at 500 mb may prove sufficient to move these storms off the higher terrain and into lower elevations of southern/central AZ through the evening. A deeply mixed boundary layer is expected to be in place across this area, which will encourage strong/gusty downdraft winds potentially producing isolated damage. Marginally severe hail may also occur with more discrete initial development. These storms should move westward through the evening posing mainly a wind threat before eventually weakening as convective inhibition slowly increases. ...Florida... Strong low-level shear and outer rain bands associated with Hurricane Dorian are forecast to remain generally offshore and to the east of the southern/central FL Peninsula through the period. See the latest advisories from the National Hurricane Center for more information on other hazards associated with Hurricane Dorian. ..Gleason/Squitieri.. 09/01/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OH VALLEY...NORTHERN/CENTRAL PLAINS...AND SOUTHERN/CENTRAL AZ... ...SUMMARY... Isolated severe storms may occur mainly this afternoon across parts of the Ohio Valley, this evening/tonight across portions of the northern/central Plains, and this afternoon/evening over parts of southern/central Arizona. ...Ohio Valley... Within broadly cyclonic flow over eastern Canada and the Great Lakes, a weak shortwave trough will move across parts of the OH Valley today. Modest ascent associated with this feature should encourage at least scattered storm development by the afternoon from eastern IN into northern KY and OH. This convection should then spread eastward across parts of WV into western PA through the early evening. Even though mid-level lapse rates will remain modest, diurnal heating will contribute to around 1000-2000 J/kg of MLCAPE across most of this region by this afternoon. A veering wind profile in low levels combined with around 20-30 kt of mid-level west-southwesterly flow may support occasional storm organization. Small multicells/clusters capable of producing isolated strong to damaging winds appear to be the main threat. This risk should quickly diminish with eastward extent into PA by late evening as instability wanes. ...Northern/Central Plains... Upper ridging will remain prominent across much of the northern/central Plains through the period. An upper trough/low over BC will move eastward into AB and gradually erode the upper ridge over the northern Rockies and vicinity late tonight. At the surface, a low will develop eastward across central/eastern MT from this evening through early Monday morning. An EML with steep mid-level lapse rates will gradually overspread much of the northern/central Plains though tonight. Greater low-level moisture will likely remain confined along/south of a surface boundary that will be located near the SD/NE border through this evening. Considerable uncertainty remains regarding possible convective initiation during the day, as subsidence associated with the upper ridge will probably tend to limit overall storm coverage across the northern/central Plains. A southerly low-level jet should strengthen to around 30-40 kt across western KS into central NE in the 00-06Z time frame. Warm air advection and related lift may support at least isolated storm development this evening across parts of western/central NE and vicinity. Although any storms that develop will probably be slightly elevated, steep mid-level lapse rates and rich low-level moisture will result in strong MUCAPE across this area, potentially in excess of 3000 J/kg. Around 35-45 kt of effective bulk shear will likely promote rotating updrafts with these storms, and isolated large hail may occur with any elevated supercells that form initially. Farther north, a strengthening south-southwesterly low-level jet late in the period (06-12Z) may encourage isolated convection to develop over northeastern MT/southern SK and subsequently spread southeastward along an instability gradient into parts of western/central ND early Monday morning. Overall coverage still remains uncertain, but there appears to be enough of a convective precipitation signal in short-term guidance to support inclusion of 5% probabilities for isolated instances of large hail occurring with elevated strong to severe storms given the strong shear that will be present. ...Southern/Central Arizona... An upper high will remain centered over the Four Corners region today. Orographic lift should be the main driver of isolated to widely scattered convection that should develop by early afternoon across the higher terrain of western NM and southern/central AZ. However, unlike the past couple of days, around 20 kt of easterly flow at 500 mb may prove sufficient to move these storms off the higher terrain and into lower elevations of southern/central AZ through the evening. A deeply mixed boundary layer is expected to be in place across this area, which will encourage strong/gusty downdraft winds potentially producing isolated damage. Marginally severe hail may also occur with more discrete initial development. These storms should move westward through the evening posing mainly a wind threat before eventually weakening as convective inhibition slowly increases. ...Florida... Strong low-level shear and outer rain bands associated with Hurricane Dorian are forecast to remain generally offshore and to the east of the southern/central FL Peninsula through the period. See the latest advisories from the National Hurricane Center for more information on other hazards associated with Hurricane Dorian. ..Gleason/Squitieri.. 09/01/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...Synopsis... An upper-level ridge will prevail across the western CONUS throughout the day, with an intensifying mid-level impulse beginning to crest the ridge, across the Pacific Northwest/northern Rockies regions by the end of the period. The resultant strengthening flow aloft by peak heating may be transported downward via a deep, mixed boundary layer, promoting dry and breezy conditions which may foster some threat for wildfire-spread. ...Northern Great Basin into the central Rockies... Downslope flow and boundary layer mixing of the winds aloft will result in 15-20 mph sustained west-southwesterly surface winds and 10-20% RH, from parts of the Snake River Plain into the Great Divide Basin. An elevated area has been maintained for regions where the aforementioned breezy, dry surface conditions are expected to persist for several hours during the afternoon. Fuels across this area are also quite supportive of wildfire-spread potential. Farther west-southwest into parts of the Great Basin, at least localized to briefly widespread elevated conditions may be observed, but the patchy or brief nature of such conditions precludes a delineation at this time. ...Central into southern Colorado and far northwest New Mexico... A couple of thunderstorms may initiate atop the higher terrain of the Rocky Mountains across parts of central Colorado into Northwest New Mexico during the afternoon hours. These storms may be high-based in nature, with a couple of dry strikes possible, and where fuels are marginally to modestly receptive to fire spread. The very sparse nature of dry strikes renders an isolated dry thunderstorm delineation unwarranted at this time. ..Squitieri.. 09/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...Synopsis... An upper-level ridge will prevail across the western CONUS throughout the day, with an intensifying mid-level impulse beginning to crest the ridge, across the Pacific Northwest/northern Rockies regions by the end of the period. The resultant strengthening flow aloft by peak heating may be transported downward via a deep, mixed boundary layer, promoting dry and breezy conditions which may foster some threat for wildfire-spread. ...Northern Great Basin into the central Rockies... Downslope flow and boundary layer mixing of the winds aloft will result in 15-20 mph sustained west-southwesterly surface winds and 10-20% RH, from parts of the Snake River Plain into the Great Divide Basin. An elevated area has been maintained for regions where the aforementioned breezy, dry surface conditions are expected to persist for several hours during the afternoon. Fuels across this area are also quite supportive of wildfire-spread potential. Farther west-southwest into parts of the Great Basin, at least localized to briefly widespread elevated conditions may be observed, but the patchy or brief nature of such conditions precludes a delineation at this time. ...Central into southern Colorado and far northwest New Mexico... A couple of thunderstorms may initiate atop the higher terrain of the Rocky Mountains across parts of central Colorado into Northwest New Mexico during the afternoon hours. These storms may be high-based in nature, with a couple of dry strikes possible, and where fuels are marginally to modestly receptive to fire spread. The very sparse nature of dry strikes renders an isolated dry thunderstorm delineation unwarranted at this time. ..Squitieri.. 09/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Sun Sep 01 2019 Valid 011200Z - 021200Z ...Synopsis... An upper-level ridge will prevail across the western CONUS throughout the day, with an intensifying mid-level impulse beginning to crest the ridge, across the Pacific Northwest/northern Rockies regions by the end of the period. The resultant strengthening flow aloft by peak heating may be transported downward via a deep, mixed boundary layer, promoting dry and breezy conditions which may foster some threat for wildfire-spread. ...Northern Great Basin into the central Rockies... Downslope flow and boundary layer mixing of the winds aloft will result in 15-20 mph sustained west-southwesterly surface winds and 10-20% RH, from parts of the Snake River Plain into the Great Divide Basin. An elevated area has been maintained for regions where the aforementioned breezy, dry surface conditions are expected to persist for several hours during the afternoon. Fuels across this area are also quite supportive of wildfire-spread potential. Farther west-southwest into parts of the Great Basin, at least localized to briefly widespread elevated conditions may be observed, but the patchy or brief nature of such conditions precludes a delineation at this time. ...Central into southern Colorado and far northwest New Mexico... A couple of thunderstorms may initiate atop the higher terrain of the Rocky Mountains across parts of central Colorado into Northwest New Mexico during the afternoon hours. These storms may be high-based in nature, with a couple of dry strikes possible, and where fuels are marginally to modestly receptive to fire spread. The very sparse nature of dry strikes renders an isolated dry thunderstorm delineation unwarranted at this time. ..Squitieri.. 09/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 PM CDT Sat Aug 31 2019 Valid 010100Z - 011200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through the remainder of this evening and overnight. ...01Z Update... Isolated strong to severe storms that formed earlier today along a weak surface boundary across parts of KY, WV, and far western VA will continue to weaken this evening with the loss of diurnal heating and gradual reduction in instability. While occasional strong/gusty downdraft winds may be possible for the next hour or two, overall severe potential is expected to continue decreasing. Have therefore removed 5% hail/wind probabilities from this region. Weak low-level warm advection may encourage isolated storms to form across southeastern SD and vicinity later this evening and continuing through the overnight hours. Although northwesterly winds are forecast to strengthen through mid and upper-levels, mid-level lapse rates should remain modest. This will limit MUCAPE available to any elevated convection that forms, with minimal severe hail threat anticipated. Isolated to scattered showers and storms should develop this evening and overnight across parts of the mid MS Valley into the Midwest as a weak shortwave trough moves eastward across these areas. Although some modest enhancement to the mid-level flow will exist, instability will be weak, and storms will probably remain elevated above a stable boundary layer. A robust storm that developed earlier this evening across far northern CO in a weak low-level upslope flow regime has since weakened. Upper ridging remains prominent across the Rockies, and any additional storms that form in this environment will likely weaken with southward extent as convective inhibition rapidly increases with the onset of nocturnal cooling. Elsewhere, isolated to scattered convection may continue this evening and into the overnight hours across parts of the Southeast and southern High Plains. Weak shear across these regions should greatly limit any organized severe storm potential. ..Gleason.. 09/01/2019 Read more

No watches are valid as of Sat Aug 31 23:43:02 UTC 2019.

No Mesoscale Discussions are in effect as of Sat Aug 31 23:43:02 UTC 2019.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sat Aug 31 2019 Valid 312000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN KENTUCKY INTO FAR WEST-CENTRAL VIRGINIA... ...SUMMARY... A few strong storms are possible across parts of the Ohio Valley to central Appalachians this afternoon. No significant changes were made to the previous outlook. Only isolated storms are expected along the east-west instability axis from northern KY into far western VA, aided by strong heating. 18Z soundings indicate a subsidence inversion aloft, and weak shear, with only short lived, marginal wind or hail expected. ..Jewell.. 08/31/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 31 2019/ ...Ohio Valley to central Appalachians... Robust boundary-layer heating near a weakly convergent quasi-stationary front, ahead of a decaying mid-level impulse, should aid in isolated thunderstorms forming by mid afternoon. A confined corridor of modest buoyancy should develop, characterized by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a belt of 25-30 kt 500-mb southwesterlies should support transient updraft rotation in a few cells. This may yield locally strong wind gusts along with marginally severe hail. ...Northern Nebraska to southern/eastern South Dakota... While overall forcing for ascent will be limited, sufficient moist/convergence could influence isolated thunderstorm development near a weak surface/boundary across northern Nebraska/southern South Dakota. If storms develop, a severe storm or two cannot be entirely ruled out given adequate buoyancy and moderately strong northwesterly flow aloft. Storms are a bit more likely to develop later tonight across eastern South Dakota with increasing warm advection, although hail potential will tend to be limited by modest mid-level lapse rates. Overall scenario across the region currently appears too marginal/uncertain to warrant severe probabilities. ...Southern Arizona... An isolated storm or two could develop over/near the mountains of southeast Arizona this afternoon and drift generally westward. However, storm organization should be limited by weaker mid-level winds, while the strongest updrafts should be relegated to south of the international border. As such, severe wind probabilities do not appear warranted. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sat Aug 31 2019 Valid 312000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN KENTUCKY INTO FAR WEST-CENTRAL VIRGINIA... ...SUMMARY... A few strong storms are possible across parts of the Ohio Valley to central Appalachians this afternoon. No significant changes were made to the previous outlook. Only isolated storms are expected along the east-west instability axis from northern KY into far western VA, aided by strong heating. 18Z soundings indicate a subsidence inversion aloft, and weak shear, with only short lived, marginal wind or hail expected. ..Jewell.. 08/31/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 31 2019/ ...Ohio Valley to central Appalachians... Robust boundary-layer heating near a weakly convergent quasi-stationary front, ahead of a decaying mid-level impulse, should aid in isolated thunderstorms forming by mid afternoon. A confined corridor of modest buoyancy should develop, characterized by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a belt of 25-30 kt 500-mb southwesterlies should support transient updraft rotation in a few cells. This may yield locally strong wind gusts along with marginally severe hail. ...Northern Nebraska to southern/eastern South Dakota... While overall forcing for ascent will be limited, sufficient moist/convergence could influence isolated thunderstorm development near a weak surface/boundary across northern Nebraska/southern South Dakota. If storms develop, a severe storm or two cannot be entirely ruled out given adequate buoyancy and moderately strong northwesterly flow aloft. Storms are a bit more likely to develop later tonight across eastern South Dakota with increasing warm advection, although hail potential will tend to be limited by modest mid-level lapse rates. Overall scenario across the region currently appears too marginal/uncertain to warrant severe probabilities. ...Southern Arizona... An isolated storm or two could develop over/near the mountains of southeast Arizona this afternoon and drift generally westward. However, storm organization should be limited by weaker mid-level winds, while the strongest updrafts should be relegated to south of the international border. As such, severe wind probabilities do not appear warranted. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sat Aug 31 2019 Valid 312000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN KENTUCKY INTO FAR WEST-CENTRAL VIRGINIA... ...SUMMARY... A few strong storms are possible across parts of the Ohio Valley to central Appalachians this afternoon. No significant changes were made to the previous outlook. Only isolated storms are expected along the east-west instability axis from northern KY into far western VA, aided by strong heating. 18Z soundings indicate a subsidence inversion aloft, and weak shear, with only short lived, marginal wind or hail expected. ..Jewell.. 08/31/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 31 2019/ ...Ohio Valley to central Appalachians... Robust boundary-layer heating near a weakly convergent quasi-stationary front, ahead of a decaying mid-level impulse, should aid in isolated thunderstorms forming by mid afternoon. A confined corridor of modest buoyancy should develop, characterized by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a belt of 25-30 kt 500-mb southwesterlies should support transient updraft rotation in a few cells. This may yield locally strong wind gusts along with marginally severe hail. ...Northern Nebraska to southern/eastern South Dakota... While overall forcing for ascent will be limited, sufficient moist/convergence could influence isolated thunderstorm development near a weak surface/boundary across northern Nebraska/southern South Dakota. If storms develop, a severe storm or two cannot be entirely ruled out given adequate buoyancy and moderately strong northwesterly flow aloft. Storms are a bit more likely to develop later tonight across eastern South Dakota with increasing warm advection, although hail potential will tend to be limited by modest mid-level lapse rates. Overall scenario across the region currently appears too marginal/uncertain to warrant severe probabilities. ...Southern Arizona... An isolated storm or two could develop over/near the mountains of southeast Arizona this afternoon and drift generally westward. However, storm organization should be limited by weaker mid-level winds, while the strongest updrafts should be relegated to south of the international border. As such, severe wind probabilities do not appear warranted. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sat Aug 31 2019 Valid 312000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN KENTUCKY INTO FAR WEST-CENTRAL VIRGINIA... ...SUMMARY... A few strong storms are possible across parts of the Ohio Valley to central Appalachians this afternoon. No significant changes were made to the previous outlook. Only isolated storms are expected along the east-west instability axis from northern KY into far western VA, aided by strong heating. 18Z soundings indicate a subsidence inversion aloft, and weak shear, with only short lived, marginal wind or hail expected. ..Jewell.. 08/31/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 31 2019/ ...Ohio Valley to central Appalachians... Robust boundary-layer heating near a weakly convergent quasi-stationary front, ahead of a decaying mid-level impulse, should aid in isolated thunderstorms forming by mid afternoon. A confined corridor of modest buoyancy should develop, characterized by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a belt of 25-30 kt 500-mb southwesterlies should support transient updraft rotation in a few cells. This may yield locally strong wind gusts along with marginally severe hail. ...Northern Nebraska to southern/eastern South Dakota... While overall forcing for ascent will be limited, sufficient moist/convergence could influence isolated thunderstorm development near a weak surface/boundary across northern Nebraska/southern South Dakota. If storms develop, a severe storm or two cannot be entirely ruled out given adequate buoyancy and moderately strong northwesterly flow aloft. Storms are a bit more likely to develop later tonight across eastern South Dakota with increasing warm advection, although hail potential will tend to be limited by modest mid-level lapse rates. Overall scenario across the region currently appears too marginal/uncertain to warrant severe probabilities. ...Southern Arizona... An isolated storm or two could develop over/near the mountains of southeast Arizona this afternoon and drift generally westward. However, storm organization should be limited by weaker mid-level winds, while the strongest updrafts should be relegated to south of the international border. As such, severe wind probabilities do not appear warranted. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0244 PM CDT Sat Aug 31 2019 Valid 312000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHERN KENTUCKY INTO FAR WEST-CENTRAL VIRGINIA... ...SUMMARY... A few strong storms are possible across parts of the Ohio Valley to central Appalachians this afternoon. No significant changes were made to the previous outlook. Only isolated storms are expected along the east-west instability axis from northern KY into far western VA, aided by strong heating. 18Z soundings indicate a subsidence inversion aloft, and weak shear, with only short lived, marginal wind or hail expected. ..Jewell.. 08/31/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 31 2019/ ...Ohio Valley to central Appalachians... Robust boundary-layer heating near a weakly convergent quasi-stationary front, ahead of a decaying mid-level impulse, should aid in isolated thunderstorms forming by mid afternoon. A confined corridor of modest buoyancy should develop, characterized by MLCAPE of 1000-1500 J/kg. While low-level winds will be weak, a belt of 25-30 kt 500-mb southwesterlies should support transient updraft rotation in a few cells. This may yield locally strong wind gusts along with marginally severe hail. ...Northern Nebraska to southern/eastern South Dakota... While overall forcing for ascent will be limited, sufficient moist/convergence could influence isolated thunderstorm development near a weak surface/boundary across northern Nebraska/southern South Dakota. If storms develop, a severe storm or two cannot be entirely ruled out given adequate buoyancy and moderately strong northwesterly flow aloft. Storms are a bit more likely to develop later tonight across eastern South Dakota with increasing warm advection, although hail potential will tend to be limited by modest mid-level lapse rates. Overall scenario across the region currently appears too marginal/uncertain to warrant severe probabilities. ...Southern Arizona... An isolated storm or two could develop over/near the mountains of southeast Arizona this afternoon and drift generally westward. However, storm organization should be limited by weaker mid-level winds, while the strongest updrafts should be relegated to south of the international border. As such, severe wind probabilities do not appear warranted. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0141 PM CDT Sat Aug 31 2019 Valid 011200Z - 021200Z The primary change with this forecast update was to expand the elevated fire weather area farther east across southern portions of Wyoming. While this area will be on the extreme southern periphery of the stronger mid-level flow, breezy westerly/northwesterly downslope winds amidst critically-lowered RH values and receptive fuels should foster several hours of Elevated fire weather conditions during the afternoon. While locally critically conditions are possible -- especially over the Sawtooth Mountains and Snake River plain in Idaho, the northern Wasatch Mountains in Utah, and across portions of southeast Wyoming -- the coverage of sustained wind speeds at or above 20 mph appears too limited/brief to introduce a critical fire weather area at this time. An elevated fire weather area was also considered over portions of northwest Nevada, where afternoon breeziness will overlap a large area of critical RH values (i.e., < 15%). While Vaisala National Lightning Detection Network cloud-to-ground lightning data over the past 72-hours does indicate a few flashes (and potential holdovers) occurred nearby, most of these were west of where the breezy winds are expected. Additionally, the brief/spotty nature of the threat precludes the introduction of an elevated fire weather area at this time. ..Elliott.. 08/31/2019 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Aug 31 2019/ ...Synopsis... A vigorous mid-level shortwave trough will translate across the upper-level ridge axis over the Pacific Northwest, northern Rockies, and northern Great Basin areas on Day 2/Sunday. As a result, dry and breezy surface conditions due to the mass response associated with the passing shortwave will encourage at least a few hours of wildfire-spread potential across parts of the northwest CONUS. In addition, afternoon heating atop the higher terrain of the Rockies in central Colorado may encourage the development of a few high based storms capable of very sparse, dry lightning strikes. ...Central Rockies into the Great Basin... Widespread west-southwesterly sustained surface winds exceeding 15 mph are expected by peak afternoon heating, that in tandem with 10-20% RH, will foster conditions favorable for fire-spread through at least sunset. Fuels are quite dry across much of the Great Basin into the central Rockies. Currently, an elevated delineation is in place across parts of the Snake River Plain and surrounding locations, where aforementioned stronger flow aloft/synoptic forcing will overlap most favorably with the aforementioned elevated conditions. Widespread elevated conditions may also occur across much of the central Great Basin, but given that the strongest upper-level support will likely remain north of the area, and lack of run-to-run consistency among model guidance members, an elevated delineation will be withheld at this time. ...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 0141 PM CDT Sat Aug 31 2019 Valid 011200Z - 021200Z The primary change with this forecast update was to expand the elevated fire weather area farther east across southern portions of Wyoming. While this area will be on the extreme southern periphery of the stronger mid-level flow, breezy westerly/northwesterly downslope winds amidst critically-lowered RH values and receptive fuels should foster several hours of Elevated fire weather conditions during the afternoon. While locally critically conditions are possible -- especially over the Sawtooth Mountains and Snake River plain in Idaho, the northern Wasatch Mountains in Utah, and across portions of southeast Wyoming -- the coverage of sustained wind speeds at or above 20 mph appears too limited/brief to introduce a critical fire weather area at this time. An elevated fire weather area was also considered over portions of northwest Nevada, where afternoon breeziness will overlap a large area of critical RH values (i.e., < 15%). While Vaisala National Lightning Detection Network cloud-to-ground lightning data over the past 72-hours does indicate a few flashes (and potential holdovers) occurred nearby, most of these were west of where the breezy winds are expected. Additionally, the brief/spotty nature of the threat precludes the introduction of an elevated fire weather area at this time. ..Elliott.. 08/31/2019 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Aug 31 2019/ ...Synopsis... A vigorous mid-level shortwave trough will translate across the upper-level ridge axis over the Pacific Northwest, northern Rockies, and northern Great Basin areas on Day 2/Sunday. As a result, dry and breezy surface conditions due to the mass response associated with the passing shortwave will encourage at least a few hours of wildfire-spread potential across parts of the northwest CONUS. In addition, afternoon heating atop the higher terrain of the Rockies in central Colorado may encourage the development of a few high based storms capable of very sparse, dry lightning strikes. ...Central Rockies into the Great Basin... Widespread west-southwesterly sustained surface winds exceeding 15 mph are expected by peak afternoon heating, that in tandem with 10-20% RH, will foster conditions favorable for fire-spread through at least sunset. Fuels are quite dry across much of the Great Basin into the central Rockies. Currently, an elevated delineation is in place across parts of the Snake River Plain and surrounding locations, where aforementioned stronger flow aloft/synoptic forcing will overlap most favorably with the aforementioned elevated conditions. Widespread elevated conditions may also occur across much of the central Great Basin, but given that the strongest upper-level support will likely remain north of the area, and lack of run-to-run consistency among model guidance members, an elevated delineation will be withheld at this time. ...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 0141 PM CDT Sat Aug 31 2019 Valid 011200Z - 021200Z The primary change with this forecast update was to expand the elevated fire weather area farther east across southern portions of Wyoming. While this area will be on the extreme southern periphery of the stronger mid-level flow, breezy westerly/northwesterly downslope winds amidst critically-lowered RH values and receptive fuels should foster several hours of Elevated fire weather conditions during the afternoon. While locally critically conditions are possible -- especially over the Sawtooth Mountains and Snake River plain in Idaho, the northern Wasatch Mountains in Utah, and across portions of southeast Wyoming -- the coverage of sustained wind speeds at or above 20 mph appears too limited/brief to introduce a critical fire weather area at this time. An elevated fire weather area was also considered over portions of northwest Nevada, where afternoon breeziness will overlap a large area of critical RH values (i.e., < 15%). While Vaisala National Lightning Detection Network cloud-to-ground lightning data over the past 72-hours does indicate a few flashes (and potential holdovers) occurred nearby, most of these were west of where the breezy winds are expected. Additionally, the brief/spotty nature of the threat precludes the introduction of an elevated fire weather area at this time. ..Elliott.. 08/31/2019 .PREV DISCUSSION... /ISSUED 0146 AM CDT Sat Aug 31 2019/ ...Synopsis... A vigorous mid-level shortwave trough will translate across the upper-level ridge axis over the Pacific Northwest, northern Rockies, and northern Great Basin areas on Day 2/Sunday. As a result, dry and breezy surface conditions due to the mass response associated with the passing shortwave will encourage at least a few hours of wildfire-spread potential across parts of the northwest CONUS. In addition, afternoon heating atop the higher terrain of the Rockies in central Colorado may encourage the development of a few high based storms capable of very sparse, dry lightning strikes. ...Central Rockies into the Great Basin... Widespread west-southwesterly sustained surface winds exceeding 15 mph are expected by peak afternoon heating, that in tandem with 10-20% RH, will foster conditions favorable for fire-spread through at least sunset. Fuels are quite dry across much of the Great Basin into the central Rockies. Currently, an elevated delineation is in place across parts of the Snake River Plain and surrounding locations, where aforementioned stronger flow aloft/synoptic forcing will overlap most favorably with the aforementioned elevated conditions. Widespread elevated conditions may also occur across much of the central Great Basin, but given that the strongest upper-level support will likely remain north of the area, and lack of run-to-run consistency among model guidance members, an elevated delineation will be withheld at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more