Severe Storms

MD 1926 CONCERNING SEVERE POTENTIAL...TORNADO WATCH LIKELY FOR SC GRAND STRAND AND SOUTHERN COASTAL NC
Mesoscale Discussion 1926 NWS Storm Prediction Center Norman OK 0216 AM CDT Thu Sep 05 2019 Areas affected...SC Grand Strand and southern coastal NC Concerning...Severe potential...Tornado Watch likely Valid 050716Z - 050915Z Probability of Watch Issuance...80 percent SUMMARY...A tornado watch will likely be needed before 5am EDT as supercells, located within an outer band of Hurricane Dorian, move to the near-coastal waters of Long Bay and the NC/SC coastal plain. DISCUSSION...Radar mosaic imagery shows an outer convective band arcing from near Myrtle Beach east over the Gulf Stream as Hurricane Dorian moves towards the Carolina coast. Several weak/transient circulations associated with miniature supercells have been noted within this convective band during the past 1-2 hours. The distance between the circulations and the coastline has steadily decreased with 30nm currently between the coast and the leading supercells. Subjective surface analysis places a maritime warm front arcing north and northeastward along the immediate shelf waters with surface dewpoints in the lower 70s degree F west and middle-upper 70s F east. The boundary is likely to slowly overspread the Cape Lookout and Cape Fear areas before dawn. The 06z MHX raob showed only 200 J/kg MLCAPE but was located on the relatively drier/less unstable side of the boundary. RAP forecast soundings for the coastal area of the NC/SC border indicate MLCAPE will increase into the 500-1000 J/kg over the next 1-2 hours as richer low-level moisture infiltrates the immediate coast. The KLTX VAD shows around 400 m2/s^2 0-1km SRH when inputting observed storm motions. All of the above factors will likely contribute to a risk for supercell tornadoes beginning near the coast of the NC/SC border and gradually spreading northward past Cape Fear early this morning. ..Smith/Grams.. 09/05/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MHX...ILM... LAT...LON 33537911 33887902 34577809 34627760 33857690 33167780 33207864 33537911 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0119 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... Winds will remain light across the western CONUS on Friday which will limit the overall threat for large fire spread. An upper-level trough will move from the Pacific Northwest into the northern Rockies with thunderstorm activity expected. However increasing moisture associated with this trough will lead to more wet storm modes and should limit the threat for additional fire starts. ..Bentley.. 09/05/2019 ...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 0119 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... Winds will remain light across the western CONUS on Friday which will limit the overall threat for large fire spread. An upper-level trough will move from the Pacific Northwest into the northern Rockies with thunderstorm activity expected. However increasing moisture associated with this trough will lead to more wet storm modes and should limit the threat for additional fire starts. ..Bentley.. 09/05/2019 ...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 0119 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... Winds will remain light across the western CONUS on Friday which will limit the overall threat for large fire spread. An upper-level trough will move from the Pacific Northwest into the northern Rockies with thunderstorm activity expected. However increasing moisture associated with this trough will lead to more wet storm modes and should limit the threat for additional fire starts. ..Bentley.. 09/05/2019 ...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 0119 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...NO CRITICAL AREAS... ...Synopsis... Winds will remain light across the western CONUS on Friday which will limit the overall threat for large fire spread. An upper-level trough will move from the Pacific Northwest into the northern Rockies with thunderstorm activity expected. However increasing moisture associated with this trough will lead to more wet storm modes and should limit the threat for additional fire starts. ..Bentley.. 09/05/2019 ...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 0118 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...Synopsis... A potent upper-level trough is moving into the Pacific Northwest this morning with numerous lightning being observed in northern California. Some of these storms are expected to continue into the morning hours today before a brief lull is likely during late morning and early afternoon. Additional thunderstorms are expected during the afternoon as surface temperatures warm. PWAT values across much of the Northwest will be in the 0.75" range which, combined with storm speeds around 30 mph, will support a threat for dry thunderstorms. Otherwise, light winds are expected across much of the dry portions in the western CONUS which will limit the threat for large fire spread. ..Bentley.. 09/05/2019 ...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 0118 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...Synopsis... A potent upper-level trough is moving into the Pacific Northwest this morning with numerous lightning being observed in northern California. Some of these storms are expected to continue into the morning hours today before a brief lull is likely during late morning and early afternoon. Additional thunderstorms are expected during the afternoon as surface temperatures warm. PWAT values across much of the Northwest will be in the 0.75" range which, combined with storm speeds around 30 mph, will support a threat for dry thunderstorms. Otherwise, light winds are expected across much of the dry portions in the western CONUS which will limit the threat for large fire spread. ..Bentley.. 09/05/2019 ...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 0118 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...Synopsis... A potent upper-level trough is moving into the Pacific Northwest this morning with numerous lightning being observed in northern California. Some of these storms are expected to continue into the morning hours today before a brief lull is likely during late morning and early afternoon. Additional thunderstorms are expected during the afternoon as surface temperatures warm. PWAT values across much of the Northwest will be in the 0.75" range which, combined with storm speeds around 30 mph, will support a threat for dry thunderstorms. Otherwise, light winds are expected across much of the dry portions in the western CONUS which will limit the threat for large fire spread. ..Bentley.. 09/05/2019 ...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 0118 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...Synopsis... A potent upper-level trough is moving into the Pacific Northwest this morning with numerous lightning being observed in northern California. Some of these storms are expected to continue into the morning hours today before a brief lull is likely during late morning and early afternoon. Additional thunderstorms are expected during the afternoon as surface temperatures warm. PWAT values across much of the Northwest will be in the 0.75" range which, combined with storm speeds around 30 mph, will support a threat for dry thunderstorms. Otherwise, light winds are expected across much of the dry portions in the western CONUS which will limit the threat for large fire spread. ..Bentley.. 09/05/2019 ...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 1225 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHERN ROCKIES... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts will be possible over a portion of the northern Rockies Friday. ...Northern Rockies region... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Boundary layer dewpoints generally in the 40s to low 50s F will support 500-1000 J/kg MLCAPE where sufficient heating of the surface layer occurs. Vertical wind profiles accompanying the upper trough with 30-35 kt effective bulk shear will generally promote multicells. Widely scattered high-based storms will likely develop over the mountains and spread east into a portion of the High Plains. Inverted-V thermodynamic profiles suggest few of the storms might produce locally strong wind gusts from mid afternoon through mid evening. ...North Carolina Coast... The center of Hurricane Dorian is forecast by the National Hurricane center to be over the NC outer banks early Friday, but will continue northeast away from shore during the day. Therefore, the more favorable quadrant for isolated tornadoes should remain offshore with minimal threat inland. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: 5% - Marginal Hail: <5% - None ..Dial.. 09/05/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHERN ROCKIES... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts will be possible over a portion of the northern Rockies Friday. ...Northern Rockies region... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Boundary layer dewpoints generally in the 40s to low 50s F will support 500-1000 J/kg MLCAPE where sufficient heating of the surface layer occurs. Vertical wind profiles accompanying the upper trough with 30-35 kt effective bulk shear will generally promote multicells. Widely scattered high-based storms will likely develop over the mountains and spread east into a portion of the High Plains. Inverted-V thermodynamic profiles suggest few of the storms might produce locally strong wind gusts from mid afternoon through mid evening. ...North Carolina Coast... The center of Hurricane Dorian is forecast by the National Hurricane center to be over the NC outer banks early Friday, but will continue northeast away from shore during the day. Therefore, the more favorable quadrant for isolated tornadoes should remain offshore with minimal threat inland. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: 5% - Marginal Hail: <5% - None ..Dial.. 09/05/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHERN ROCKIES... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts will be possible over a portion of the northern Rockies Friday. ...Northern Rockies region... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Boundary layer dewpoints generally in the 40s to low 50s F will support 500-1000 J/kg MLCAPE where sufficient heating of the surface layer occurs. Vertical wind profiles accompanying the upper trough with 30-35 kt effective bulk shear will generally promote multicells. Widely scattered high-based storms will likely develop over the mountains and spread east into a portion of the High Plains. Inverted-V thermodynamic profiles suggest few of the storms might produce locally strong wind gusts from mid afternoon through mid evening. ...North Carolina Coast... The center of Hurricane Dorian is forecast by the National Hurricane center to be over the NC outer banks early Friday, but will continue northeast away from shore during the day. Therefore, the more favorable quadrant for isolated tornadoes should remain offshore with minimal threat inland. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: 5% - Marginal Hail: <5% - None ..Dial.. 09/05/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Thu Sep 05 2019 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHERN ROCKIES... ...SUMMARY... A few thunderstorms capable of isolated strong wind gusts will be possible over a portion of the northern Rockies Friday. ...Northern Rockies region... A shortwave trough will suppress the northern periphery of an upper ridge and continue through the northern Rockies Friday. Boundary layer dewpoints generally in the 40s to low 50s F will support 500-1000 J/kg MLCAPE where sufficient heating of the surface layer occurs. Vertical wind profiles accompanying the upper trough with 30-35 kt effective bulk shear will generally promote multicells. Widely scattered high-based storms will likely develop over the mountains and spread east into a portion of the High Plains. Inverted-V thermodynamic profiles suggest few of the storms might produce locally strong wind gusts from mid afternoon through mid evening. ...North Carolina Coast... The center of Hurricane Dorian is forecast by the National Hurricane center to be over the NC outer banks early Friday, but will continue northeast away from shore during the day. Therefore, the more favorable quadrant for isolated tornadoes should remain offshore with minimal threat inland. ...MAXIMUM RISK BY HAZARD... Tornado: <2% - None Wind: 5% - Marginal Hail: <5% - None ..Dial.. 09/05/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY THROUGH TONIGHT ACROSS PARTS OF THE COASTAL CAROLINAS... ...SUMMARY... Some risk for a couple of tornadoes could develop across parts of the coastal Carolinas today through tonight in association with Hurricane Dorian. A couple of strong thunderstorms may also impact parts of the Upper Midwest, and portions of western and central Oregon, accompanied by at least some risk for severe hail and wind. ...Synopsis... The stronger westerlies will remain confined to the northern tier of the U.S. and Canada through this period. Models suggest that some amplification within this regime is possible across the northeast Pacific through the Canadian Rockies, with short wave ridging building inland of the British Columbia coast, downstream of a significant progressive short wave trough over the northeast Pacific. Preceding the latter feature, a weaker short wave is forecast to advance inland of the northern California and Oregon coast, while subtropical ridging (centered near/east of the Colorado Rockies) otherwise maintains a prominent influence across much of the remainder of the West/Rockies and Plains. Downstream of the ridging, the most prominent impulse within the westerlies appears likely to continue rapidly progressing through larger-scale mid/upper troughing, across Quebec/Newfoundland and Labrador and the Canadian Maritimes. Meanwhile, within much weaker troughing at lower latitudes, Hurricane Dorian is expected to, at least initially, continue a slow northeastward migration near the Carolina coast. However, by tonight, an acceleration toward the North Carolina Outer Banks vicinity is forecast, as at least one short wave impulse within the westerlies digs across the Canadian/U.S. border through the Upper Midwest/Great Lakes region. Seasonably moist air has largely become confined to portions of the Southwest, Deep South Texas, and Southeast coastal areas, to the north and west of Dorian, and in the wake of an initial surface front which has advanced off the New England and northern Mid Atlantic coast, as well as into the lower Ohio/lower and middle Missouri Valleys. Considerable further drying into and through the Southeast and Gulf Coast appears likely today through tonight, in the wake of Dorian. However, substantive northward moisture return does appear possible ahead of the troughing advancing inland of the Pacific coast. ...Carolina coastal areas... Potential for convection capable of producing tornadoes will largely hinge on the inland advection of tropical boundary layer moisture, now present offshore, as evolving clockwise curved low-level hodographs become characterized by strong to extreme shear in the right front quadrant (with respect to storm motion) of Dorian. Based on the most probable track of the low-level cyclonic circulation center, this may come close to coastal areas, but could remain mostly offshore through this period. There may be some window of opportunity for increasing potential for tornadoes near northeastern South Carolina and southern North Carolina coastal areas this morning into midday, then mainly near the North Carolina Outer Banks vicinity later today through tonight, as the hurricane turns northeastward and roughly parallels the coast. ...Upper Midwest... Scattered thunderstorm development, in the presence of steep lower/mid tropospheric lapse rates and strong vertical shear within the convective layer, may pose a risk for marginally severe hail and wind. This will largely be focused along a zone of enhanced lower/mid tropospheric warm advection, associated with a couple of digging shortwaves within increasingly northwesterly mid-level flow. ...Near/east of the Oregon Cascades... Stronger mid/upper forcing for ascent associated with the inland progressing short wave, in combination with strengthening southwesterly mid-level flow (30-40 kt around 500 mb), deep boundary layer mixing and destabilization aided by mid-level moistening, may provide support for scattered afternoon storms which could pose a risk for marginally severe hail and strong wind gusts. ..Kerr/Bentley.. 09/05/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY THROUGH TONIGHT ACROSS PARTS OF THE COASTAL CAROLINAS... ...SUMMARY... Some risk for a couple of tornadoes could develop across parts of the coastal Carolinas today through tonight in association with Hurricane Dorian. A couple of strong thunderstorms may also impact parts of the Upper Midwest, and portions of western and central Oregon, accompanied by at least some risk for severe hail and wind. ...Synopsis... The stronger westerlies will remain confined to the northern tier of the U.S. and Canada through this period. Models suggest that some amplification within this regime is possible across the northeast Pacific through the Canadian Rockies, with short wave ridging building inland of the British Columbia coast, downstream of a significant progressive short wave trough over the northeast Pacific. Preceding the latter feature, a weaker short wave is forecast to advance inland of the northern California and Oregon coast, while subtropical ridging (centered near/east of the Colorado Rockies) otherwise maintains a prominent influence across much of the remainder of the West/Rockies and Plains. Downstream of the ridging, the most prominent impulse within the westerlies appears likely to continue rapidly progressing through larger-scale mid/upper troughing, across Quebec/Newfoundland and Labrador and the Canadian Maritimes. Meanwhile, within much weaker troughing at lower latitudes, Hurricane Dorian is expected to, at least initially, continue a slow northeastward migration near the Carolina coast. However, by tonight, an acceleration toward the North Carolina Outer Banks vicinity is forecast, as at least one short wave impulse within the westerlies digs across the Canadian/U.S. border through the Upper Midwest/Great Lakes region. Seasonably moist air has largely become confined to portions of the Southwest, Deep South Texas, and Southeast coastal areas, to the north and west of Dorian, and in the wake of an initial surface front which has advanced off the New England and northern Mid Atlantic coast, as well as into the lower Ohio/lower and middle Missouri Valleys. Considerable further drying into and through the Southeast and Gulf Coast appears likely today through tonight, in the wake of Dorian. However, substantive northward moisture return does appear possible ahead of the troughing advancing inland of the Pacific coast. ...Carolina coastal areas... Potential for convection capable of producing tornadoes will largely hinge on the inland advection of tropical boundary layer moisture, now present offshore, as evolving clockwise curved low-level hodographs become characterized by strong to extreme shear in the right front quadrant (with respect to storm motion) of Dorian. Based on the most probable track of the low-level cyclonic circulation center, this may come close to coastal areas, but could remain mostly offshore through this period. There may be some window of opportunity for increasing potential for tornadoes near northeastern South Carolina and southern North Carolina coastal areas this morning into midday, then mainly near the North Carolina Outer Banks vicinity later today through tonight, as the hurricane turns northeastward and roughly parallels the coast. ...Upper Midwest... Scattered thunderstorm development, in the presence of steep lower/mid tropospheric lapse rates and strong vertical shear within the convective layer, may pose a risk for marginally severe hail and wind. This will largely be focused along a zone of enhanced lower/mid tropospheric warm advection, associated with a couple of digging shortwaves within increasingly northwesterly mid-level flow. ...Near/east of the Oregon Cascades... Stronger mid/upper forcing for ascent associated with the inland progressing short wave, in combination with strengthening southwesterly mid-level flow (30-40 kt around 500 mb), deep boundary layer mixing and destabilization aided by mid-level moistening, may provide support for scattered afternoon storms which could pose a risk for marginally severe hail and strong wind gusts. ..Kerr/Bentley.. 09/05/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY THROUGH TONIGHT ACROSS PARTS OF THE COASTAL CAROLINAS... ...SUMMARY... Some risk for a couple of tornadoes could develop across parts of the coastal Carolinas today through tonight in association with Hurricane Dorian. A couple of strong thunderstorms may also impact parts of the Upper Midwest, and portions of western and central Oregon, accompanied by at least some risk for severe hail and wind. ...Synopsis... The stronger westerlies will remain confined to the northern tier of the U.S. and Canada through this period. Models suggest that some amplification within this regime is possible across the northeast Pacific through the Canadian Rockies, with short wave ridging building inland of the British Columbia coast, downstream of a significant progressive short wave trough over the northeast Pacific. Preceding the latter feature, a weaker short wave is forecast to advance inland of the northern California and Oregon coast, while subtropical ridging (centered near/east of the Colorado Rockies) otherwise maintains a prominent influence across much of the remainder of the West/Rockies and Plains. Downstream of the ridging, the most prominent impulse within the westerlies appears likely to continue rapidly progressing through larger-scale mid/upper troughing, across Quebec/Newfoundland and Labrador and the Canadian Maritimes. Meanwhile, within much weaker troughing at lower latitudes, Hurricane Dorian is expected to, at least initially, continue a slow northeastward migration near the Carolina coast. However, by tonight, an acceleration toward the North Carolina Outer Banks vicinity is forecast, as at least one short wave impulse within the westerlies digs across the Canadian/U.S. border through the Upper Midwest/Great Lakes region. Seasonably moist air has largely become confined to portions of the Southwest, Deep South Texas, and Southeast coastal areas, to the north and west of Dorian, and in the wake of an initial surface front which has advanced off the New England and northern Mid Atlantic coast, as well as into the lower Ohio/lower and middle Missouri Valleys. Considerable further drying into and through the Southeast and Gulf Coast appears likely today through tonight, in the wake of Dorian. However, substantive northward moisture return does appear possible ahead of the troughing advancing inland of the Pacific coast. ...Carolina coastal areas... Potential for convection capable of producing tornadoes will largely hinge on the inland advection of tropical boundary layer moisture, now present offshore, as evolving clockwise curved low-level hodographs become characterized by strong to extreme shear in the right front quadrant (with respect to storm motion) of Dorian. Based on the most probable track of the low-level cyclonic circulation center, this may come close to coastal areas, but could remain mostly offshore through this period. There may be some window of opportunity for increasing potential for tornadoes near northeastern South Carolina and southern North Carolina coastal areas this morning into midday, then mainly near the North Carolina Outer Banks vicinity later today through tonight, as the hurricane turns northeastward and roughly parallels the coast. ...Upper Midwest... Scattered thunderstorm development, in the presence of steep lower/mid tropospheric lapse rates and strong vertical shear within the convective layer, may pose a risk for marginally severe hail and wind. This will largely be focused along a zone of enhanced lower/mid tropospheric warm advection, associated with a couple of digging shortwaves within increasingly northwesterly mid-level flow. ...Near/east of the Oregon Cascades... Stronger mid/upper forcing for ascent associated with the inland progressing short wave, in combination with strengthening southwesterly mid-level flow (30-40 kt around 500 mb), deep boundary layer mixing and destabilization aided by mid-level moistening, may provide support for scattered afternoon storms which could pose a risk for marginally severe hail and strong wind gusts. ..Kerr/Bentley.. 09/05/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Thu Sep 05 2019 Valid 051200Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY THROUGH TONIGHT ACROSS PARTS OF THE COASTAL CAROLINAS... ...SUMMARY... Some risk for a couple of tornadoes could develop across parts of the coastal Carolinas today through tonight in association with Hurricane Dorian. A couple of strong thunderstorms may also impact parts of the Upper Midwest, and portions of western and central Oregon, accompanied by at least some risk for severe hail and wind. ...Synopsis... The stronger westerlies will remain confined to the northern tier of the U.S. and Canada through this period. Models suggest that some amplification within this regime is possible across the northeast Pacific through the Canadian Rockies, with short wave ridging building inland of the British Columbia coast, downstream of a significant progressive short wave trough over the northeast Pacific. Preceding the latter feature, a weaker short wave is forecast to advance inland of the northern California and Oregon coast, while subtropical ridging (centered near/east of the Colorado Rockies) otherwise maintains a prominent influence across much of the remainder of the West/Rockies and Plains. Downstream of the ridging, the most prominent impulse within the westerlies appears likely to continue rapidly progressing through larger-scale mid/upper troughing, across Quebec/Newfoundland and Labrador and the Canadian Maritimes. Meanwhile, within much weaker troughing at lower latitudes, Hurricane Dorian is expected to, at least initially, continue a slow northeastward migration near the Carolina coast. However, by tonight, an acceleration toward the North Carolina Outer Banks vicinity is forecast, as at least one short wave impulse within the westerlies digs across the Canadian/U.S. border through the Upper Midwest/Great Lakes region. Seasonably moist air has largely become confined to portions of the Southwest, Deep South Texas, and Southeast coastal areas, to the north and west of Dorian, and in the wake of an initial surface front which has advanced off the New England and northern Mid Atlantic coast, as well as into the lower Ohio/lower and middle Missouri Valleys. Considerable further drying into and through the Southeast and Gulf Coast appears likely today through tonight, in the wake of Dorian. However, substantive northward moisture return does appear possible ahead of the troughing advancing inland of the Pacific coast. ...Carolina coastal areas... Potential for convection capable of producing tornadoes will largely hinge on the inland advection of tropical boundary layer moisture, now present offshore, as evolving clockwise curved low-level hodographs become characterized by strong to extreme shear in the right front quadrant (with respect to storm motion) of Dorian. Based on the most probable track of the low-level cyclonic circulation center, this may come close to coastal areas, but could remain mostly offshore through this period. There may be some window of opportunity for increasing potential for tornadoes near northeastern South Carolina and southern North Carolina coastal areas this morning into midday, then mainly near the North Carolina Outer Banks vicinity later today through tonight, as the hurricane turns northeastward and roughly parallels the coast. ...Upper Midwest... Scattered thunderstorm development, in the presence of steep lower/mid tropospheric lapse rates and strong vertical shear within the convective layer, may pose a risk for marginally severe hail and wind. This will largely be focused along a zone of enhanced lower/mid tropospheric warm advection, associated with a couple of digging shortwaves within increasingly northwesterly mid-level flow. ...Near/east of the Oregon Cascades... Stronger mid/upper forcing for ascent associated with the inland progressing short wave, in combination with strengthening southwesterly mid-level flow (30-40 kt around 500 mb), deep boundary layer mixing and destabilization aided by mid-level moistening, may provide support for scattered afternoon storms which could pose a risk for marginally severe hail and strong wind gusts. ..Kerr/Bentley.. 09/05/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0746 PM CDT Wed Sep 04 2019 Valid 050100Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE TONIGHT ACROSS NORTHEASTERN SOUTH CAROLINA AND SOUTHERN NORTH CAROLINA COASTAL AREAS... ...SUMMARY... The potential for a couple of tornadoes may increase late tonight near northeastern South Carolina and southern North Carolina coastal areas. ...01Z Outlook Update... ...South Atlantic Coast... At least some evaporative cooling, within steady convective precipitation to the north and west of the center of Dorian, is maintaining a relatively cool and stable (as suggested by latest observational data and objective analysis) boundary layer across much of South Carolina and Georgia coastal areas and offshore waters. Based on the expected slow north-northeastward motion of Dorian, there might not be much change overnight. However, toward 12Z, near surface flow may gradually take on a more substantive easterly component (as opposed to northeasterly) near northeastern South Carolina/southern North Carolina coastal areas, accompanied by an influx of tropical boundary layer air (including mid/upper 70s surface dew points ) which could become more conducive to tornado potential in the presence of enlarging low-level hodographs (becoming characterized by strong to extreme shear). ...Northern Plains... A low amplitude short wave trough over southern Saskatchewan is forecast to turn eastward and southeastward across into the eastern North Dakota/Minnesota international border area by daybreak. Models suggest that this may be accompanied by a zone of strengthening lower/mid tropospheric warm advection across parts of eastern North Dakota into northwestern Minnesota by 06-08Z, with CAPE for moistening parcels rooted within this layer increasing in excess of 1000 J/kg. Coupled with moderately strong, unidirectional shear within the convective layer, the environment could become conducive storms posing at least some risk for severe hail. ..Kerr.. 09/05/2019 Read more

WW 0634 Status Updates
000-050040- STATUS REPORT ON WW 634 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 S ABE TO 15 SSE EWR TO 5 SW JFK TO 25 W BDR TO 10 N BDR TO 15 WNW GON TO 20 NNE GON TO 5 WSW PVD. ..GLEASON..09/04/19 ATTN...WFO...OKX...BOX...ALY...GYX...PHI...BGM...BTV... STATUS REPORT FOR WS 634 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS CTC001-007-009-011-050040- CT . CONNECTICUT COUNTIES INCLUDED ARE FAIRFIELD MIDDLESEX NEW HAVEN NEW LONDON NJC021-023-025-050040- NJ . NEW JERSEY COUNTIES INCLUDED ARE MERCER MIDDLESEX MONMOUTH NYC059-103-050040- NY . NEW YORK COUNTIES INCLUDED ARE NASSAU SUFFOLK Read more

WW 634 SEVERE TSTM CT MA ME NH NJ NY PA RI VT CW 041650Z - 050100Z
0-050100- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 634 NWS Storm Prediction Center Norman OK 1250 PM EDT Wed Sep 4 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Connecticut Massachusetts Southern Maine New Hampshire Northern New Jersey Southern and Eastern New York Eastern Pennsylvania Rhode Island Southern Vermont Coastal Waters * Effective this Wednesday afternoon and evening from 1250 PM until 900 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Multiple corridors of intensifying thunderstorm development are expected this afternoon along and ahead of a cold front. Adequate instability along with very strong deep-layer winds will yield the potential for storms capable of damaging winds and some hail. A tornado or two cannot be ruled out mainly across southeast New York into southern New England. The severe risk will diminish from west to east across the region by early/mid-evening. The severe thunderstorm watch area is approximately along and 100 statute miles east and west of a line from 30 miles north of Laconia NH to 35 miles east southeast of Allentown PA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 28030. ...Guyer Read more