Severe Storms

No watches are valid as of Wed Sep 4 15:21:01 UTC 2019.

MD 1924 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF CENTRAL/EASTERN NY...VT...NH...WESTERN ME...MA...CT...AND FAR NORTHEAST PA
Mesoscale Discussion 1924 NWS Storm Prediction Center Norman OK 1019 AM CDT Wed Sep 04 2019 Areas affected...Portions of Central/Eastern NY...VT...NH...Western ME...MA...CT...and Far Northeast PA Concerning...Severe potential...Watch likely Valid 041519Z - 041715Z Probability of Watch Issuance...80 percent SUMMARY...Increasing thunderstorm coverage is anticipated over the next several hours. Damaging wind gusts are the primary severe threat but a couple tornadoes are also possible. A watch will eventually be needed for portions of the region. DISCUSSION...Recent surface analysis places a cold front from SLK (in far northern NY) southwestward across central NY to just east of BFD (in far north-central PA). Radar trends have shown gradually increasing intensity of the cells along the front in south-central NY as they move into a diurnally destabilizing and modestly buoyant air mass downstream. Ongoing moisture advection has lead to an 2-4 degree increase in dewpoints downstream across the Hudson Valley and this general trends is expected to continue, leading to air-mass destabilization ahead of the front as far north as northeast NY, VT, NH, and western ME. At the same time, strengthening large-scale forcing for ascent attendant to the shortwave trough moving into the Northeast will augment the frontal forcing already occurring. The combination of this increased forcing for ascent and air-mass destabilization is expected to result in expanding thunderstorm coverage over the next few hours. Even with the modest buoyancy, strong vertical shear will provide a kinematic environment supportive of organized storms. Primary threat will be damaging wind gusts associated with bowing line segments. However, given the southerly flow across southeastern NY and southern New England, some tornado threat also exists, especially with any more discrete cells ahead of the front. A watch will likely be needed by early afternoon, particularly over eastern NY and New England. ..Mosier/Guyer.. 09/04/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...CTP... LAT...LON 41747693 42387681 43827469 44847352 44597056 42547148 41537287 41317494 41747693 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Sep 04 2019 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST AND COASTAL SC... ...SUMMARY... Scattered damaging winds and a couple tornadoes are possible through about 8 PM EDT across parts of the Mid-Atlantic States and New England. A few tornadoes may occur along the coast of South Carolina, mainly tonight through early morning Thursday. ...Mid-Atlantic States and New England... A shortwave trough from southwest QC to the Lower Great Lakes will progress east with trailing portion shifting across New England this evening. Attendant surface cold front will reach the Champlain and Hudson Valleys by afternoon with trailing portion arcing southwest across the central Appalachians. Ongoing convection within the warm conveyor just ahead of the front should persist east, with additional development expected in its immediate wake along the front by midday. Mid 60s to low 70s surface dew points are prevalent from CT/RI southwest into the Mid-Atlantic States. As a plume of steeper mid-level lapse rates sampled by the 12Z Pittsburgh sounding spreads east, MLCAPE of 750-1500 J/kg should develop amid pockets of greater insolation in the lee of the Appalachians. Strong 700-500 mb southwesterlies will prevail from PA/NJ northeastward, with more modest flow to the southwest. This setup should favor multiple clusters/line segments with embedded supercell structures, most likely from eastern PA/NJ into southwest ME. Damaging winds will probably be the main threat given the strength of the low/mid-level flow, but isolated marginally severe hail could also occur. A couple tornadoes are possible, centered on the corridor with the greatest combination of moderate low-level SRH and buoyancy from southeast NY to NH. ...SC Coast and vicinity... Hurricane Dorian is expected to continue slowly north off the FL/GA coast and approach coastal SC by 12Z Thursday. The overall tornado threat is expected to remain limited through this afternoon along the GA/SC coast. Greater potential for a few tornadoes should develop this evening into the overnight across coastal SC as low-level northeasterlies substantially strengthen and hodographs enlarge within the favored northeast quadrant. This may yield a few low-topped supercells within one or more outer bands that approach the immediate coast of SC into far southern NC. ...Deep South TX... TC Fernand will continue west across far northeast Mexico. Moderate low-level easterly flow will support adequate SRH for perhaps a brief tornado and/or isolated thunderstorm wind damage with scattered convection that persists from the northwest Gulf across Deep South TX. This flow should subside during the evening, limiting the severe storm risk tonight. ...Red River Valley of the North.. A low-amplitude shortwave trough near the BC/AB/MT border will move east along the international border towards the Lake of the Woods region by 12Z Thursday. 700-mb warm advection will strengthen across northeast ND into northwest MN tonight. A cluster of elevated storms may evolve southeast from southeast SK/southwest MB overnight. Thin buoyancy will be a limiting factor, but robust speed shear within the cloud-bearing layer could support a few instances of marginally severe hail. ..Grams/Smith.. 09/04/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Sep 04 2019 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST AND COASTAL SC... ...SUMMARY... Scattered damaging winds and a couple tornadoes are possible through about 8 PM EDT across parts of the Mid-Atlantic States and New England. A few tornadoes may occur along the coast of South Carolina, mainly tonight through early morning Thursday. ...Mid-Atlantic States and New England... A shortwave trough from southwest QC to the Lower Great Lakes will progress east with trailing portion shifting across New England this evening. Attendant surface cold front will reach the Champlain and Hudson Valleys by afternoon with trailing portion arcing southwest across the central Appalachians. Ongoing convection within the warm conveyor just ahead of the front should persist east, with additional development expected in its immediate wake along the front by midday. Mid 60s to low 70s surface dew points are prevalent from CT/RI southwest into the Mid-Atlantic States. As a plume of steeper mid-level lapse rates sampled by the 12Z Pittsburgh sounding spreads east, MLCAPE of 750-1500 J/kg should develop amid pockets of greater insolation in the lee of the Appalachians. Strong 700-500 mb southwesterlies will prevail from PA/NJ northeastward, with more modest flow to the southwest. This setup should favor multiple clusters/line segments with embedded supercell structures, most likely from eastern PA/NJ into southwest ME. Damaging winds will probably be the main threat given the strength of the low/mid-level flow, but isolated marginally severe hail could also occur. A couple tornadoes are possible, centered on the corridor with the greatest combination of moderate low-level SRH and buoyancy from southeast NY to NH. ...SC Coast and vicinity... Hurricane Dorian is expected to continue slowly north off the FL/GA coast and approach coastal SC by 12Z Thursday. The overall tornado threat is expected to remain limited through this afternoon along the GA/SC coast. Greater potential for a few tornadoes should develop this evening into the overnight across coastal SC as low-level northeasterlies substantially strengthen and hodographs enlarge within the favored northeast quadrant. This may yield a few low-topped supercells within one or more outer bands that approach the immediate coast of SC into far southern NC. ...Deep South TX... TC Fernand will continue west across far northeast Mexico. Moderate low-level easterly flow will support adequate SRH for perhaps a brief tornado and/or isolated thunderstorm wind damage with scattered convection that persists from the northwest Gulf across Deep South TX. This flow should subside during the evening, limiting the severe storm risk tonight. ...Red River Valley of the North.. A low-amplitude shortwave trough near the BC/AB/MT border will move east along the international border towards the Lake of the Woods region by 12Z Thursday. 700-mb warm advection will strengthen across northeast ND into northwest MN tonight. A cluster of elevated storms may evolve southeast from southeast SK/southwest MB overnight. Thin buoyancy will be a limiting factor, but robust speed shear within the cloud-bearing layer could support a few instances of marginally severe hail. ..Grams/Smith.. 09/04/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Sep 04 2019 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST AND COASTAL SC... ...SUMMARY... Scattered damaging winds and a couple tornadoes are possible through about 8 PM EDT across parts of the Mid-Atlantic States and New England. A few tornadoes may occur along the coast of South Carolina, mainly tonight through early morning Thursday. ...Mid-Atlantic States and New England... A shortwave trough from southwest QC to the Lower Great Lakes will progress east with trailing portion shifting across New England this evening. Attendant surface cold front will reach the Champlain and Hudson Valleys by afternoon with trailing portion arcing southwest across the central Appalachians. Ongoing convection within the warm conveyor just ahead of the front should persist east, with additional development expected in its immediate wake along the front by midday. Mid 60s to low 70s surface dew points are prevalent from CT/RI southwest into the Mid-Atlantic States. As a plume of steeper mid-level lapse rates sampled by the 12Z Pittsburgh sounding spreads east, MLCAPE of 750-1500 J/kg should develop amid pockets of greater insolation in the lee of the Appalachians. Strong 700-500 mb southwesterlies will prevail from PA/NJ northeastward, with more modest flow to the southwest. This setup should favor multiple clusters/line segments with embedded supercell structures, most likely from eastern PA/NJ into southwest ME. Damaging winds will probably be the main threat given the strength of the low/mid-level flow, but isolated marginally severe hail could also occur. A couple tornadoes are possible, centered on the corridor with the greatest combination of moderate low-level SRH and buoyancy from southeast NY to NH. ...SC Coast and vicinity... Hurricane Dorian is expected to continue slowly north off the FL/GA coast and approach coastal SC by 12Z Thursday. The overall tornado threat is expected to remain limited through this afternoon along the GA/SC coast. Greater potential for a few tornadoes should develop this evening into the overnight across coastal SC as low-level northeasterlies substantially strengthen and hodographs enlarge within the favored northeast quadrant. This may yield a few low-topped supercells within one or more outer bands that approach the immediate coast of SC into far southern NC. ...Deep South TX... TC Fernand will continue west across far northeast Mexico. Moderate low-level easterly flow will support adequate SRH for perhaps a brief tornado and/or isolated thunderstorm wind damage with scattered convection that persists from the northwest Gulf across Deep South TX. This flow should subside during the evening, limiting the severe storm risk tonight. ...Red River Valley of the North.. A low-amplitude shortwave trough near the BC/AB/MT border will move east along the international border towards the Lake of the Woods region by 12Z Thursday. 700-mb warm advection will strengthen across northeast ND into northwest MN tonight. A cluster of elevated storms may evolve southeast from southeast SK/southwest MB overnight. Thin buoyancy will be a limiting factor, but robust speed shear within the cloud-bearing layer could support a few instances of marginally severe hail. ..Grams/Smith.. 09/04/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Sep 04 2019 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST AND COASTAL SC... ...SUMMARY... Scattered damaging winds and a couple tornadoes are possible through about 8 PM EDT across parts of the Mid-Atlantic States and New England. A few tornadoes may occur along the coast of South Carolina, mainly tonight through early morning Thursday. ...Mid-Atlantic States and New England... A shortwave trough from southwest QC to the Lower Great Lakes will progress east with trailing portion shifting across New England this evening. Attendant surface cold front will reach the Champlain and Hudson Valleys by afternoon with trailing portion arcing southwest across the central Appalachians. Ongoing convection within the warm conveyor just ahead of the front should persist east, with additional development expected in its immediate wake along the front by midday. Mid 60s to low 70s surface dew points are prevalent from CT/RI southwest into the Mid-Atlantic States. As a plume of steeper mid-level lapse rates sampled by the 12Z Pittsburgh sounding spreads east, MLCAPE of 750-1500 J/kg should develop amid pockets of greater insolation in the lee of the Appalachians. Strong 700-500 mb southwesterlies will prevail from PA/NJ northeastward, with more modest flow to the southwest. This setup should favor multiple clusters/line segments with embedded supercell structures, most likely from eastern PA/NJ into southwest ME. Damaging winds will probably be the main threat given the strength of the low/mid-level flow, but isolated marginally severe hail could also occur. A couple tornadoes are possible, centered on the corridor with the greatest combination of moderate low-level SRH and buoyancy from southeast NY to NH. ...SC Coast and vicinity... Hurricane Dorian is expected to continue slowly north off the FL/GA coast and approach coastal SC by 12Z Thursday. The overall tornado threat is expected to remain limited through this afternoon along the GA/SC coast. Greater potential for a few tornadoes should develop this evening into the overnight across coastal SC as low-level northeasterlies substantially strengthen and hodographs enlarge within the favored northeast quadrant. This may yield a few low-topped supercells within one or more outer bands that approach the immediate coast of SC into far southern NC. ...Deep South TX... TC Fernand will continue west across far northeast Mexico. Moderate low-level easterly flow will support adequate SRH for perhaps a brief tornado and/or isolated thunderstorm wind damage with scattered convection that persists from the northwest Gulf across Deep South TX. This flow should subside during the evening, limiting the severe storm risk tonight. ...Red River Valley of the North.. A low-amplitude shortwave trough near the BC/AB/MT border will move east along the international border towards the Lake of the Woods region by 12Z Thursday. 700-mb warm advection will strengthen across northeast ND into northwest MN tonight. A cluster of elevated storms may evolve southeast from southeast SK/southwest MB overnight. Thin buoyancy will be a limiting factor, but robust speed shear within the cloud-bearing layer could support a few instances of marginally severe hail. ..Grams/Smith.. 09/04/2019 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0345 AM CDT Wed Sep 04 2019 Valid 071200Z - 121200Z ...DISCUSSION... Model consensus is that upper synoptic pattern will transition to quasi-zonal day 4, but with general trend toward establishing a trough in the west day 5. A low-amplitude shortwave trough will emerge over the northern Plains day 4 (Saturday), but forcing with this feature should remain on cool side of a front that will reside across the central Plains. Storms developing in vicinity of this boundary might pose a marginal severe threat Saturday afternoon and evening. Day 5 (Sunday) upper ridging will build across the Plains, while a shortwave trough moves through the Great Basin and central Rockies. Warm advection storms may develop on the cool side of the stationary front across the central and northern Plains, but severe threat should remain limited. Severe potential might increase over the central/northern Plains day 6 (Monday) in association with an ejecting shortwave trough. However, antecedent conditions will be characterized by widespread storms developing north of a warm front which lowers confidence in destabilization potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0345 AM CDT Wed Sep 04 2019 Valid 071200Z - 121200Z ...DISCUSSION... Model consensus is that upper synoptic pattern will transition to quasi-zonal day 4, but with general trend toward establishing a trough in the west day 5. A low-amplitude shortwave trough will emerge over the northern Plains day 4 (Saturday), but forcing with this feature should remain on cool side of a front that will reside across the central Plains. Storms developing in vicinity of this boundary might pose a marginal severe threat Saturday afternoon and evening. Day 5 (Sunday) upper ridging will build across the Plains, while a shortwave trough moves through the Great Basin and central Rockies. Warm advection storms may develop on the cool side of the stationary front across the central and northern Plains, but severe threat should remain limited. Severe potential might increase over the central/northern Plains day 6 (Monday) in association with an ejecting shortwave trough. However, antecedent conditions will be characterized by widespread storms developing north of a warm front which lowers confidence in destabilization potential. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0345 AM CDT Wed Sep 04 2019 Valid 071200Z - 121200Z ...DISCUSSION... Model consensus is that upper synoptic pattern will transition to quasi-zonal day 4, but with general trend toward establishing a trough in the west day 5. A low-amplitude shortwave trough will emerge over the northern Plains day 4 (Saturday), but forcing with this feature should remain on cool side of a front that will reside across the central Plains. Storms developing in vicinity of this boundary might pose a marginal severe threat Saturday afternoon and evening. Day 5 (Sunday) upper ridging will build across the Plains, while a shortwave trough moves through the Great Basin and central Rockies. Warm advection storms may develop on the cool side of the stationary front across the central and northern Plains, but severe threat should remain limited. Severe potential might increase over the central/northern Plains day 6 (Monday) in association with an ejecting shortwave trough. However, antecedent conditions will be characterized by widespread storms developing north of a warm front which lowers confidence in destabilization potential. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0208 AM CDT Wed Sep 04 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHEAST MONTANA...NORTHEAST WYOMING AND WESTERN SOUTH DAKOTA... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts and hail will be possible from southeast Montana, northeast Wyoming into far western South Dakota Friday. ...Southeast Montana, northeast Wyoming and western South Dakota... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Downstream from this feature, a narrow corridor of low 50s F dewpoints should reside from eastern WY, southeast MT into western SD beneath steep mid-level lapse rates supporting 1500 J/kg MLCAPE. Widely scattered storms will likely develop over the higher terrain and spread east into a portion of the High Plains. The stronger winds aloft will likely remain west of the corridor of greater instability with generally weak vertical shear supportive of multicells. A few of the storms may produce locally strong wind gusts and marginally severe hail through mid evening. ...North Carolina Coast... Dorian is forecast by the National Hurricane center to be off the northern NC coast early Friday and continue northeast away from shore during the day. Therefore, the tornado threat inland should remain low. ..Dial.. 09/04/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0208 AM CDT Wed Sep 04 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTHEAST MONTANA...NORTHEAST WYOMING AND WESTERN SOUTH DAKOTA... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts and hail will be possible from southeast Montana, northeast Wyoming into far western South Dakota Friday. ...Southeast Montana, northeast Wyoming and western South Dakota... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Downstream from this feature, a narrow corridor of low 50s F dewpoints should reside from eastern WY, southeast MT into western SD beneath steep mid-level lapse rates supporting 1500 J/kg MLCAPE. Widely scattered storms will likely develop over the higher terrain and spread east into a portion of the High Plains. The stronger winds aloft will likely remain west of the corridor of greater instability with generally weak vertical shear supportive of multicells. A few of the storms may produce locally strong wind gusts and marginally severe hail through mid evening. ...North Carolina Coast... Dorian is forecast by the National Hurricane center to be off the northern NC coast early Friday and continue northeast away from shore during the day. Therefore, the tornado threat inland should remain low. ..Dial.. 09/04/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0138 AM CDT Wed Sep 04 2019 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... A mid-level ridge will remain fortified across the western CONUS, with a pronounced mid-level shortwave trough traversing the northern California/Pacific Northwest vicinity on Day 2/Thursday. Deep-layer ascent associated with the aforementioned trough will promote isolated to potentially scattered thunderstorm development throughout much of the afternoon and evening hours, with a couple of storms producing dry strikes. ...Northern California into the Pacific Northwest and northwestern Great Basin... Isolated to potentially scattered thunderstorm development is expected by mid-afternoon, as the aforementioned shortwave trough impinges on the area. While copious lightning may accompany the longer-lived, more organized storms, precipitable water values approaching 1 inch and clustering/training of stronger storm cores suggests that wetting rainfall may be abundant, despite faster storm motions and high cloud bases. An isolated dry thunderstorm delineation was withheld at this time given the amount of wetting rains possible. Nonetheless, at least a few dry strikes may occur, with potential fire starts aggravated by erratic gusty winds associated with the stronger storms. Please see the Day 2 Convective Outlook for more information regarding the severe wind threat. ..Squitieri.. 09/04/2019 ...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 0138 AM CDT Wed Sep 04 2019 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... A mid-level ridge will remain fortified across the western CONUS, with a pronounced mid-level shortwave trough traversing the northern California/Pacific Northwest vicinity on Day 2/Thursday. Deep-layer ascent associated with the aforementioned trough will promote isolated to potentially scattered thunderstorm development throughout much of the afternoon and evening hours, with a couple of storms producing dry strikes. ...Northern California into the Pacific Northwest and northwestern Great Basin... Isolated to potentially scattered thunderstorm development is expected by mid-afternoon, as the aforementioned shortwave trough impinges on the area. While copious lightning may accompany the longer-lived, more organized storms, precipitable water values approaching 1 inch and clustering/training of stronger storm cores suggests that wetting rainfall may be abundant, despite faster storm motions and high cloud bases. An isolated dry thunderstorm delineation was withheld at this time given the amount of wetting rains possible. Nonetheless, at least a few dry strikes may occur, with potential fire starts aggravated by erratic gusty winds associated with the stronger storms. Please see the Day 2 Convective Outlook for more information regarding the severe wind threat. ..Squitieri.. 09/04/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 1 NWS Storm Prediction Center Norman OK 0110 AM CDT Wed Sep 04 2019 Valid 041200Z - 051200Z CORRECTED FOR GRAPHIC ...Synopsis... A mid-level ridge will hold firm across the western CONUS. Nonetheless, a mid-level shortwave trough embedded in the larger scale flow will crest the ridge and traverse the northern Rockies, encouraging a mass response for surface dry, breezy conditions, which may be favorable for some wildfire-spread. Also, a second mid-level impulse will impinge on the California coastline, promoting deep-layer ascent across northern portions of California into the western Great Basin, where at least isolated thunderstorm potential will exist. ...Northern and central Rockies... By peak afternoon heating, the surface isallobaric response to a glancing mid-level shortwave, combined with boundary layer mixing of the stronger flow aloft to the surface, will foster 15-20 mph sustained westerly surface winds and 15-25% RH. Finer fuels have sufficiently dried across the region to support at least modest wildfire-spread potential, with an elevated area remaining in place across parts of northern Montana. At least localized elevated conditions may also occur farther south to the Montana/Idaho border, but the patchy and brief nature of these conditions precludes a delineation across this area at this time. Widespread 10-15 mph westerly winds and critically low RH are expected across portions of central into eastern Wyoming during the afternoon as well. While fuels have recently become receptive to fire spread across portions of this area, model guidance struggles to show more widespread winds exceeding 15 mph, hence no elevated delineation at this time, though trends will continue to be monitored for a possible elevated area addition in the next forecast update. ...Northern California into the western Great Basin... Storms are first expected to initiate mainly across northern Nevada by afternoon peak heating. Later, storms are expected to initiate across northern California during the evening/overnight hours. Modest storm motions and wetting rainfall may be the biggest inhibiting factors to a more robust lightning-induced fire threat. Nonetheless, precipitable water values in the 0.50-0.75 inch range will foster at least isolated dry strikes on the peripheral of updrafts atop near-critical to critically dry fuels. As such, maintaining an isolated dry thunderstorm delineation across northern California into the western Great Basin appears warranted. ..Squitieri.. 09/04/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 1 NWS Storm Prediction Center Norman OK 0110 AM CDT Wed Sep 04 2019 Valid 041200Z - 051200Z CORRECTED FOR GRAPHIC ...Synopsis... A mid-level ridge will hold firm across the western CONUS. Nonetheless, a mid-level shortwave trough embedded in the larger scale flow will crest the ridge and traverse the northern Rockies, encouraging a mass response for surface dry, breezy conditions, which may be favorable for some wildfire-spread. Also, a second mid-level impulse will impinge on the California coastline, promoting deep-layer ascent across northern portions of California into the western Great Basin, where at least isolated thunderstorm potential will exist. ...Northern and central Rockies... By peak afternoon heating, the surface isallobaric response to a glancing mid-level shortwave, combined with boundary layer mixing of the stronger flow aloft to the surface, will foster 15-20 mph sustained westerly surface winds and 15-25% RH. Finer fuels have sufficiently dried across the region to support at least modest wildfire-spread potential, with an elevated area remaining in place across parts of northern Montana. At least localized elevated conditions may also occur farther south to the Montana/Idaho border, but the patchy and brief nature of these conditions precludes a delineation across this area at this time. Widespread 10-15 mph westerly winds and critically low RH are expected across portions of central into eastern Wyoming during the afternoon as well. While fuels have recently become receptive to fire spread across portions of this area, model guidance struggles to show more widespread winds exceeding 15 mph, hence no elevated delineation at this time, though trends will continue to be monitored for a possible elevated area addition in the next forecast update. ...Northern California into the western Great Basin... Storms are first expected to initiate mainly across northern Nevada by afternoon peak heating. Later, storms are expected to initiate across northern California during the evening/overnight hours. Modest storm motions and wetting rainfall may be the biggest inhibiting factors to a more robust lightning-induced fire threat. Nonetheless, precipitable water values in the 0.50-0.75 inch range will foster at least isolated dry strikes on the peripheral of updrafts atop near-critical to critically dry fuels. As such, maintaining an isolated dry thunderstorm delineation across northern California into the western Great Basin appears warranted. ..Squitieri.. 09/04/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 1 NWS Storm Prediction Center Norman OK 0110 AM CDT Wed Sep 04 2019 Valid 041200Z - 051200Z CORRECTED FOR GRAPHIC ...Synopsis... A mid-level ridge will hold firm across the western CONUS. Nonetheless, a mid-level shortwave trough embedded in the larger scale flow will crest the ridge and traverse the northern Rockies, encouraging a mass response for surface dry, breezy conditions, which may be favorable for some wildfire-spread. Also, a second mid-level impulse will impinge on the California coastline, promoting deep-layer ascent across northern portions of California into the western Great Basin, where at least isolated thunderstorm potential will exist. ...Northern and central Rockies... By peak afternoon heating, the surface isallobaric response to a glancing mid-level shortwave, combined with boundary layer mixing of the stronger flow aloft to the surface, will foster 15-20 mph sustained westerly surface winds and 15-25% RH. Finer fuels have sufficiently dried across the region to support at least modest wildfire-spread potential, with an elevated area remaining in place across parts of northern Montana. At least localized elevated conditions may also occur farther south to the Montana/Idaho border, but the patchy and brief nature of these conditions precludes a delineation across this area at this time. Widespread 10-15 mph westerly winds and critically low RH are expected across portions of central into eastern Wyoming during the afternoon as well. While fuels have recently become receptive to fire spread across portions of this area, model guidance struggles to show more widespread winds exceeding 15 mph, hence no elevated delineation at this time, though trends will continue to be monitored for a possible elevated area addition in the next forecast update. ...Northern California into the western Great Basin... Storms are first expected to initiate mainly across northern Nevada by afternoon peak heating. Later, storms are expected to initiate across northern California during the evening/overnight hours. Modest storm motions and wetting rainfall may be the biggest inhibiting factors to a more robust lightning-induced fire threat. Nonetheless, precipitable water values in the 0.50-0.75 inch range will foster at least isolated dry strikes on the peripheral of updrafts atop near-critical to critically dry fuels. As such, maintaining an isolated dry thunderstorm delineation across northern California into the western Great Basin appears warranted. ..Squitieri.. 09/04/2019 ...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 1229 AM CDT Wed Sep 04 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE EXTREME NORTHEAST SOUTH CAROLINA COAST THROUGH COASTAL NORTH CAROLINA... ...SUMMARY... Isolated tornadoes will be possible Thursday in association with Hurricane Dorian from northern coastal South Carolina through coastal North Carolina. Isolated downburst winds will be possible over a portion of western and central Oregon Thursday afternoon. ...Eastern Carolinas... Hurricane Dorian is forecast by the National Hurricane Center (NHC) to be located just off the central South Carolina coast Thursday morning and off southeast North Carolina coast Thursday evening. Based on this forecast, increasingly large low-level hodographs north of the center will evolve across northeast South Carolina and eastern North Carolina where very moist onshore winds will result in modest buoyancy. Mini supercells developing north of the center over the Gulf Stream and moving onshore will be capable of producing isolated tornadoes, especially along and inland of the North Carolina coast. ...Western and central Oregon... Steep mid-level lapse rates will spread across Oregon downstream from a shortwave trough that will move inland later Thursday afternoon and evening. Dewpoints will mix down into the 40s F during the day with inverted-V boundary layers and MLCAPE of 500 J/kg. Destabilization and increasing forcing for ascent downstream from the shortwave trough will support at least isolated high-based storms developing later during the afternoon and evening. Effective bulk shear will increase to 35-40 kt with approach of the trough supporting potential for a few storms to develop mid-level rotation. Isolated downburst winds and possibly hail may occur with the stronger storms. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 5% - Marginal Hail: 5% - Marginal ..Dial.. 09/04/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 AM CDT Wed Sep 04 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE EXTREME NORTHEAST SOUTH CAROLINA COAST THROUGH COASTAL NORTH CAROLINA... ...SUMMARY... Isolated tornadoes will be possible Thursday in association with Hurricane Dorian from northern coastal South Carolina through coastal North Carolina. Isolated downburst winds will be possible over a portion of western and central Oregon Thursday afternoon. ...Eastern Carolinas... Hurricane Dorian is forecast by the National Hurricane Center (NHC) to be located just off the central South Carolina coast Thursday morning and off southeast North Carolina coast Thursday evening. Based on this forecast, increasingly large low-level hodographs north of the center will evolve across northeast South Carolina and eastern North Carolina where very moist onshore winds will result in modest buoyancy. Mini supercells developing north of the center over the Gulf Stream and moving onshore will be capable of producing isolated tornadoes, especially along and inland of the North Carolina coast. ...Western and central Oregon... Steep mid-level lapse rates will spread across Oregon downstream from a shortwave trough that will move inland later Thursday afternoon and evening. Dewpoints will mix down into the 40s F during the day with inverted-V boundary layers and MLCAPE of 500 J/kg. Destabilization and increasing forcing for ascent downstream from the shortwave trough will support at least isolated high-based storms developing later during the afternoon and evening. Effective bulk shear will increase to 35-40 kt with approach of the trough supporting potential for a few storms to develop mid-level rotation. Isolated downburst winds and possibly hail may occur with the stronger storms. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 5% - Marginal Hail: 5% - Marginal ..Dial.. 09/04/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 AM CDT Wed Sep 04 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE EXTREME NORTHEAST SOUTH CAROLINA COAST THROUGH COASTAL NORTH CAROLINA... ...SUMMARY... Isolated tornadoes will be possible Thursday in association with Hurricane Dorian from northern coastal South Carolina through coastal North Carolina. Isolated downburst winds will be possible over a portion of western and central Oregon Thursday afternoon. ...Eastern Carolinas... Hurricane Dorian is forecast by the National Hurricane Center (NHC) to be located just off the central South Carolina coast Thursday morning and off southeast North Carolina coast Thursday evening. Based on this forecast, increasingly large low-level hodographs north of the center will evolve across northeast South Carolina and eastern North Carolina where very moist onshore winds will result in modest buoyancy. Mini supercells developing north of the center over the Gulf Stream and moving onshore will be capable of producing isolated tornadoes, especially along and inland of the North Carolina coast. ...Western and central Oregon... Steep mid-level lapse rates will spread across Oregon downstream from a shortwave trough that will move inland later Thursday afternoon and evening. Dewpoints will mix down into the 40s F during the day with inverted-V boundary layers and MLCAPE of 500 J/kg. Destabilization and increasing forcing for ascent downstream from the shortwave trough will support at least isolated high-based storms developing later during the afternoon and evening. Effective bulk shear will increase to 35-40 kt with approach of the trough supporting potential for a few storms to develop mid-level rotation. Isolated downburst winds and possibly hail may occur with the stronger storms. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 5% - Marginal Hail: 5% - Marginal ..Dial.. 09/04/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Wed Sep 04 2019 Valid 041200Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NEW ENGLAND AND THE MID-ATLANTIC...AND COASTAL SC... ...SUMMARY... Strong to severe thunderstorms capable of producing mainly damaging winds will be possible this afternoon across parts of the Mid-Atlantic and New England. Isolated tornadoes may occur primarily along the coast of South Carolina late tonight through early Thursday morning in association with Hurricane Dorian. ...Northeast/Mid-Atlantic... An upper trough will move eastward across the Northeast and Mid-Atlantic today. At the surface, a low will develop northeastward across Quebec through the period, with a trailing cold front shifting quickly eastward over these areas. Strong forcing for ascent associated with the upper trough along with low-level convergence along the front will likely foster robust convective development by early afternoon across NY into southern New England. 50-60 kt of mid-level southwesterly flow associated with the upper trough will overspread the warm sector, and strong shear will support organized updrafts. Generally mid 60s to lower 70s surface dewpoints should advect northeastward ahead of the front in a low-level warm air advection regime. Even though mid-level lapse rates will likely remain modest, the increasing low-level moisture and at least modest diurnal heating should promote about 1000-2000 J/kg of MLCAPE. The greatest instability should reside across the Mid-Atlantic, with gradual lessening with northeastward extent into the Northeast. By contrast, relatively stronger shear should be present farther north in New England. Regardless, there appears to be a sufficient overlap of instability and shear to support organized storms, especially from northeastern PA/northern NJ into southern New England. Given the strength of the mid-level flow and some orthogonal component to the surface front, some supercells could occur initially, with clustering potential increasing later in the afternoon. Damaging winds will probably be the main threat given the strength of the low/mid-level flow, but isolated marginally severe hail could also occur. A tornado or two cannot be ruled out, although low-level flow will have a tendency to veer to southwesterly through the afternoon, generally limiting low-level hodograph length. Farther south into southern PA/NJ and MD/DE, low-level convergence should be weaker along the front and mid-level height falls will be more subdued. Resultant overall storm coverage will probably be more isolated. Still, some threat for damaging winds should exist with any storms that can form across this area as low-level lapse rates steepen and moderate instability develops. ...Southeast Coast... Hurricane Dorian is forecast by the National Hurricane Center to continue moving north-northeastward near the coast of FL/GA/SC through the period. The overall tornado threat is expected to remain quite limited today along the east coast of FL and coastal GA as this region will remain within the western semicircle of Dorian's circulation, limiting low-level curvature and effective SRH. A somewhat greater potential for isolated tornadoes may develop late tonight into early Thursday morning across parts of coastal SC, where strengthening northeasterly low-level winds will substantially increase low-level hodographs. Low-topped supercells within one or more outer rainbands could approach the immediate coast of SC late in the period, with this isolated tornado threat likely continuing into parts of coastal NC into Day 2/Thursday. ...Deep South Texas... Tropical Storm Fernand, now over the far western Gulf of Mexico, is forecast by the National Hurricane Center to move west-northwestward across parts of northeastern Mexico through the period. Low-level shear on the northern periphery of Fernand's circulation may be sufficient to support a low risk for a brief tornado or two as low-topped cells move onshore across deep south TX. ...North Dakota/Minnesota... A low-amplitude shortwave trough now over WA/southern BC will move eastward along the international border through the period. A south-southwesterly low-level jet should strengthen across the northern/central Plains in response this evening/overnight. Elevated storms may evolve southeastward from southern MB/SK into northeastern ND and northern MN late in the period. Forecast MUCAPE appears too marginal at this time to include any probabilities for large hail, although shear is forecast to be strong across this area. ..Gleason/Squitieri.. 09/04/2019 Read more