Severe Storms

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Sun Sep 01 2019 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN ILLINOIS...EASTERN WISCONSIN...AND PARTS OF LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are possible across the western and central Great Lakes on Tuesday. ...Synopsis... A mid-level trough and associated speed max will move from the Upper Midwest eastward across the Great Lakes and into southeastern Canada on Tuesday into Tuesday night. A mid-level anticyclone will remain situated over the Four Corners while Hurricane Dorian slowly approaches the Southeast United States. In the low levels, a cold front is forecast to move southeast across the Midwest and into the lower Great Lakes. ...Great Lakes... Ongoing storms are likely in the morning across the Upper Midwest as a southwesterly LLJ and warm advection regime promote moisture transport and ascent in portions of MN/WI and the western U.P. of MI. A severe risk may accompany this activity mainly in the form of isolated damaging gusts. The northeastern extent of an elevated mixed layer with associated capping will probably overspread parts of the middle MS Valley during the day. Isolated diurnal storms are possible along the front with a hail/wind risk. Farther northeast, the magnitude of destabilization is highly dependent on the convective evolution of a possible MCS moving through the western Great Lakes during the morning. Wind fields will likely strengthen across the destabilizing warm sector during the day which will favor organized storm structures including the possibility for supercells and bowing segments. Refinements in severe probabilities will likely be needed due to mesoscale dependencies influencing the severe thunderstorm outlook. ...FL Peninsula (Hurricane Dorian)... Uncertainty remains regarding the eventual track of Hurricane Dorian as it moves into the Gulf Stream waters east of the FL Peninsula Monday night into Tuesday morning. If the northeast quadrant were to overspread the FL Peninsula on Tuesday and/or Tuesday night, then a risk for potential tornadoes would include those areas. At this time, uncertainty is too high to include low-severe probabilities. Please refer to the National Hurricane Center for the latest guidance regarding the forecast track of Hurricane Dorian. ..Smith.. 09/01/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Sun Sep 01 2019 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHERN ILLINOIS...EASTERN WISCONSIN...AND PARTS OF LOWER MICHIGAN... ...SUMMARY... Severe thunderstorms are possible across the western and central Great Lakes on Tuesday. ...Synopsis... A mid-level trough and associated speed max will move from the Upper Midwest eastward across the Great Lakes and into southeastern Canada on Tuesday into Tuesday night. A mid-level anticyclone will remain situated over the Four Corners while Hurricane Dorian slowly approaches the Southeast United States. In the low levels, a cold front is forecast to move southeast across the Midwest and into the lower Great Lakes. ...Great Lakes... Ongoing storms are likely in the morning across the Upper Midwest as a southwesterly LLJ and warm advection regime promote moisture transport and ascent in portions of MN/WI and the western U.P. of MI. A severe risk may accompany this activity mainly in the form of isolated damaging gusts. The northeastern extent of an elevated mixed layer with associated capping will probably overspread parts of the middle MS Valley during the day. Isolated diurnal storms are possible along the front with a hail/wind risk. Farther northeast, the magnitude of destabilization is highly dependent on the convective evolution of a possible MCS moving through the western Great Lakes during the morning. Wind fields will likely strengthen across the destabilizing warm sector during the day which will favor organized storm structures including the possibility for supercells and bowing segments. Refinements in severe probabilities will likely be needed due to mesoscale dependencies influencing the severe thunderstorm outlook. ...FL Peninsula (Hurricane Dorian)... Uncertainty remains regarding the eventual track of Hurricane Dorian as it moves into the Gulf Stream waters east of the FL Peninsula Monday night into Tuesday morning. If the northeast quadrant were to overspread the FL Peninsula on Tuesday and/or Tuesday night, then a risk for potential tornadoes would include those areas. At this time, uncertainty is too high to include low-severe probabilities. Please refer to the National Hurricane Center for the latest guidance regarding the forecast track of Hurricane Dorian. ..Smith.. 09/01/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0125 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PARTS OF EASTERN IDAHO... ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ..Squitieri.. 09/01/2019 ...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 0125 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PARTS OF EASTERN IDAHO... ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ..Squitieri.. 09/01/2019 ...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 0125 AM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PARTS OF EASTERN IDAHO... ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ..Squitieri.. 09/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 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