Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CDT Sat Mar 23 2024 Valid 231630Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EARLY THIS AFTERNOON OVER THE SOUTHERN TIP OF FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur early this afternoon across parts of south Florida and the Keys. ...South FL... A surface cold front continues to sag southward across the southern tip of FL into the Keys. Scattered strong thunderstorms are occurring along/ahead of the front, in a very moist/unstable and moderately sheared environment. The threat of a strong wind gust or brief spin up will persist for another 1-2 hours before the front moves through, veering low-level winds and stabilizing the air mass. Elsewhere across the CONUS, no severe storm activity is expected today. ..Hart/Thornton.. 03/23/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CDT Sat Mar 23 2024 Valid 231630Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EARLY THIS AFTERNOON OVER THE SOUTHERN TIP OF FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur early this afternoon across parts of south Florida and the Keys. ...South FL... A surface cold front continues to sag southward across the southern tip of FL into the Keys. Scattered strong thunderstorms are occurring along/ahead of the front, in a very moist/unstable and moderately sheared environment. The threat of a strong wind gust or brief spin up will persist for another 1-2 hours before the front moves through, veering low-level winds and stabilizing the air mass. Elsewhere across the CONUS, no severe storm activity is expected today. ..Hart/Thornton.. 03/23/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CDT Sat Mar 23 2024 Valid 231630Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EARLY THIS AFTERNOON OVER THE SOUTHERN TIP OF FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur early this afternoon across parts of south Florida and the Keys. ...South FL... A surface cold front continues to sag southward across the southern tip of FL into the Keys. Scattered strong thunderstorms are occurring along/ahead of the front, in a very moist/unstable and moderately sheared environment. The threat of a strong wind gust or brief spin up will persist for another 1-2 hours before the front moves through, veering low-level winds and stabilizing the air mass. Elsewhere across the CONUS, no severe storm activity is expected today. ..Hart/Thornton.. 03/23/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CDT Sat Mar 23 2024 Valid 231630Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EARLY THIS AFTERNOON OVER THE SOUTHERN TIP OF FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur early this afternoon across parts of south Florida and the Keys. ...South FL... A surface cold front continues to sag southward across the southern tip of FL into the Keys. Scattered strong thunderstorms are occurring along/ahead of the front, in a very moist/unstable and moderately sheared environment. The threat of a strong wind gust or brief spin up will persist for another 1-2 hours before the front moves through, veering low-level winds and stabilizing the air mass. Elsewhere across the CONUS, no severe storm activity is expected today. ..Hart/Thornton.. 03/23/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CDT Sat Mar 23 2024 Valid 231630Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EARLY THIS AFTERNOON OVER THE SOUTHERN TIP OF FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur early this afternoon across parts of south Florida and the Keys. ...South FL... A surface cold front continues to sag southward across the southern tip of FL into the Keys. Scattered strong thunderstorms are occurring along/ahead of the front, in a very moist/unstable and moderately sheared environment. The threat of a strong wind gust or brief spin up will persist for another 1-2 hours before the front moves through, veering low-level winds and stabilizing the air mass. Elsewhere across the CONUS, no severe storm activity is expected today. ..Hart/Thornton.. 03/23/2024 Read more

MD 0287 CONCERNING WINTER MIXED PRECIPITATION FOR PARTS OF NEW ENGLAND AND EAST-CENTRAL NY
Mesoscale Discussion 0287 NWS Storm Prediction Center Norman OK 0729 AM CDT Sat Mar 23 2024 Areas affected...Parts of New England and east-central NY Concerning...Winter mixed precipitation Valid 231229Z - 231630Z SUMMARY...A mix of heavy snow, sleet, and freezing rain will gradually shift east-northeast from east-central New York across parts of New England into early afternoon. Snowfall rates of 1-2 in/hr will persist within the heavy snow band, with liquid-equivalent rates of 0.05-0.15 in/hr common in mixed precip. DISCUSSION...A long-lived/well-developed swath of winter mixed precipitation is ongoing within a strong low-level warm theta-e advection regime across the Northeast. A band of heavy snow with rates likely near 2 in/hr is ongoing from roughly the Glens Falls, NY to Augusta, ME corridor per latest surface observations and radar imagery. This heavy snow band should pivot northeast in tandem with the shift in 850-mb frontogenesis through early afternoon. This will also yield a pivot from the ongoing west/east-orientation of the transition zone to sleet and freezing rain. As a result, southern portions of VT/NH/ME will transition to mixed precip by midday. Meanwhile, the heavy snow arc will shift more into northern parts of VT/NH to central ME. ..Grams.. 03/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CAR...GYX...BOX...BTV...ALY... LAT...LON 44027378 44377330 44987215 45297144 45517076 45737053 45857031 45866979 45446915 44586925 43986966 43477055 43157093 42997117 42757178 42687257 42707327 42767397 43227425 44027378 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...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 1031 AM CDT Sat Mar 23 2024 Valid 231700Z - 241200Z No changes, please see previous discussion. ..Nauslar.. 03/23/2024 .PREV DISCUSSION... /ISSUED 0122 AM CDT Sat Mar 23 2024/ ...Synopsis... Surface cyclone development will occur along the High Plains today with the approach and amplification of a mid-level trough across the Southwest. Return flow across Far West Texas will be dry, given low-level airmass trajectories originating from the Chihahuan Desert. Latest guidance consensus suggests that 15+ mph sustained southerly winds, coinciding with 15 percent RH atop modestly receptive fuels, will promote some potential for wildfire spread. As such, Elevated highlights have been maintained across Far West Texas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ...Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ...South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ...Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ..Edwards/Grams.. 03/23/2024 Read more

MD 0286 CONCERNING WINTER MIXED PRECIPITATION FOR PARTS OF NY INTO NEW ENGLAND
Mesoscale Discussion 0286 NWS Storm Prediction Center Norman OK 0227 AM CDT Sat Mar 23 2024 Areas affected...Parts of NY into New England Concerning...Winter mixed precipitation Valid 230727Z - 231130Z SUMMARY...A mix of heavy snow, sleet, and freezing rain will continue to spread east-northeast from parts of southern/eastern New York into New England through sunrise. Heavy snow rates of 1-1.5 in/hr will be most probable in a band along the northern periphery of the mixed transition zone. DISCUSSION...An extensive swath of mixed winter precip is ongoing across southern to eastern NY into parts of southern VT/NH. This has been aided by strong low-level warm theta-e advection amid a 50-60 kt low-level jet per ENX/BGM VWP data. Low-level warming has again been faster up the Hudson Valley than indicated by evening model guidance with prior 1"/hr snowfall rates at ALB transitioning to mixed freezing rain/sleet during the past hour. Based on recent radar trends, this mixed phase should be the dominant precip type as it gradually expands east-northeast into parts of MA and southern VT/NH in the next few hours. Precipitation rates from 0.04-0.12 in/hr should be expected based on upstream measurements/guidance. Heavier snowfall rates should still occur just to the north-northeast of the transition zone, with rates of 1-1.5 in/hr becoming increasingly probable across parts of northern VT/NH into a part of southwest ME through sunrise. ..Grams.. 03/23/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...ALY...BGM... LAT...LON 43177514 44237427 44687330 44847126 44877067 44687024 44487007 44227007 43847030 43227079 42497163 42167269 41957319 41907382 41937419 42737528 43177514 Read more