MD 2095 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN NEW YORK...WESTERN PENNSYLVANIA...SOUTHEASTERN OHIO...MUCH OF WEST VIRGINIA...WESTERN VIRGINIA...AND THE WESTERN MARYLAND PANHANDLE
Mesoscale Discussion 2095 NWS Storm Prediction Center Norman OK 0137 PM CDT Sat Sep 21 2024 Areas affected...western New York...western Pennsylvania...southeastern Ohio...much of West Virginia...western Virginia...and the western Maryland Panhandle Concerning...Severe potential...Watch unlikely Valid 211837Z - 212100Z Probability of Watch Issuance...20 percent SUMMARY...A few strong thunderstorms briefly reaching marginal severe levels can be expected through this afternoon. Marginal hail and tree damage can be expected locally. However, the very isolated/marginal nature of the risk currently expected should preclude the need for WW consideration. DISCUSSION...A weak cool front will continue moving southeastward across the Mid and Upper Ohio Valley area and into the central Appalachians today, as a vort max near Lake Huron shifts across the Lower Great Lakes toward the Chesapeake Bay area this afternoon and tonight. Ahead of the front, a modestly moist boundary layer (low 60s dewpoints) combined with warm-sector heating is resulting in around 1000 J/kg mixed-layer CAPE across much of the area, though into the 1500 to 2000 J/kg range over the middle Ohio Valley portion of the region. This destabilization is fueling a gradual increase in convective coverage and intensity near and ahead of the front -- from southeastern Ohio to southwestern New York. Though low-level flow remains weak, moderate mid-level northwesterlies are contributing to an environment amply sheared to support organized updrafts. As such, locally strong/briefly vigorous updrafts will likely be associated with marginal severe potential into early evening -- with risk spreading gradually eastward/southeastward with time. ..Goss/Guyer.. 09/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BGM...BUF...CTP...LWX...RNK...PBZ...RLX... LAT...LON 39598204 39888105 40368027 40797954 41487892 42507897 42717843 42207672 41327693 38777771 37647890 37308026 38618177 39598204 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0207 PM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... No change is needed to the ongoing forecast. Please see below for additional details. ..Marsh.. 09/21/2024 .PREV DISCUSSION... /ISSUED 0158 AM CDT Sat Sep 21 2024/ ...Synopsis... No fire weather concerns are expected on Sunday. A cool post-frontal air mass is expected across the Plains with potential for widespread precipitation. Dry conditions will continue across the southwestern US. As the upper low moves eastward across the Rockies, winds will also decrease with cooler temperatures expected across the region which will aid in keeping fire weather concerns low. ...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 0207 PM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... No change is needed to the ongoing forecast. Please see below for additional details. ..Marsh.. 09/21/2024 .PREV DISCUSSION... /ISSUED 0158 AM CDT Sat Sep 21 2024/ ...Synopsis... No fire weather concerns are expected on Sunday. A cool post-frontal air mass is expected across the Plains with potential for widespread precipitation. Dry conditions will continue across the southwestern US. As the upper low moves eastward across the Rockies, winds will also decrease with cooler temperatures expected across the region which will aid in keeping fire weather concerns low. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WEST TEXAS TO SOUTHERN MISSOURI... ...SUMMARY... Isolated severe thunderstorms are possible on Sunday from west Texas to central/southern Missouri. ...Synopsis... A filling mid-level low will move toward the central High Plains on Sunday afternoon/evening. Moderate mid-level flow will maintain southeast of this low and overspread the Oklahoma/southern Kansas vicinity. At the surface, a cold front will extend from southern Michigan across Illinois and Missouri and into Oklahoma and Texas. ...Southern Missouri across Oklahoma and into West Texas... Thunderstorms will likely be ongoing along and ahead of the surface front across the TX Panhandle and into Oklahoma and from central Kansas, across Missouri, and to southern Illinois Sunday morning. A seasonally moist airmass featuring upper 60s to perhaps low 70s dewpoints will exist ahead of the surface front Sunday afternoon/evening. Surface heating ahead of the front should result in moderate instability amid a marginally sheared airmass. A few stronger/organized storms are possible with a primary threat of damaging wind gusts, especially where any clustering or line segments can develop. Some large hail is also possible, where a few supercells are possible across northwest Texas and West Texas. The severe threat will be primarily diurnally driven with minimal severe concerns after 1-3 UTC. ..Bentley.. 09/21/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Sat Sep 21 2024 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHERN HIGH PLAINS.... ...SUMMARY... Scattered severe storms capable of all hazards are possible this afternoon and evening across portions of the southern High Plains. ...Southern High Plains... A potent upper low and associated 65-75 kt mid-level jet max centered over AZ are expected to quickly move eastward, overspreading the southern Rockies/High Plains this afternoon and evening. At the surface, sustained southerly flow ahead of a deepening surface low and trailing cold front over western NM will support moderate destabilization (MLCAPE 1500-2000 J/kg) with afternoon heating and continued low-level upslope. As the mid-level system approaches, mid-level height falls and flow aloft will intensify, elongating low and mid-level hodographs, allowing for convective development/organization in the form of supercells. One source of continued uncertainty is the ongoing elevated convection and cloud debris centered north of a diffuse surface boundary stretching from central NM to the western TX Panhandle. So far, this boundary has been slowly lifting north with pronounced low-level theta-e advection taking place to the south. As deep-layer ascent intensifies through the late morning, continued convective development to the north may support reinforcement and stalling of the boundary. The northward extent of destabilization remains unclear, though this boundary could serve as a focus for renewed development of more robust convection expected later this afternoon. Most CAM guidance shows scattered thunderstorms initiating off the higher terrain of eastern NM, or ahead of the cold front farther west by early this afternoon. These storms should quickly mature with supportive thermodynamics and kinematics, eventually spreading eastward into the TX Panhandle. The risk for large to very large hail/severe gusts will likely accompany the stronger supercells, and a threat for a couple tornadoes may be realized later this afternoon/early evening from eastern NM into parts of adjacent west TX, especially near the boundary where low-level shear may be locally enhanced. ...Upper Midwest and MO Valley... A second upper low near the international border is forecast to quickly move eastward reaching the western Great Lakes by early this evening. Weak ascent is expected ahead of a surging cold front and diffuse wave cyclone across the northern MO valley and southern MN. Surface moistening with a warm front lifting north near the IA/MN border may act as a focus for more robust convective development along the cold front late this afternoon. Increasingly orthogonal deep-layer flow and steeping low/mid-level lapse rates could support a mix of supercells and multi-cell clusters. A few of the stronger storms may pose some hail/wind threat, which should peak in intensity during the early evening. However, somewhat limited heating and the lack of broader forcing for ascent suggests storm coverage should remain isolated. ...Western PA into the Mid Atlantic... Short-wave troughing across the upper OH Valley within mid-level northwesterly flow is expected to support isolated to widely scattered thunderstorms across western PA/VA later this afternoon. Model forecast soundings with moderate buoyancy and modest deep-layer shear would imply some of the stronger storms being capable of an isolated risk for wind damage (50-60 mph) and perhaps some hail. This activity will likely diminish by early evening coincident with nocturnal cooling. ..Lyons/Goss.. 09/21/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Sat Sep 21 2024 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHERN HIGH PLAINS.... ...SUMMARY... Scattered severe storms capable of all hazards are possible this afternoon and evening across portions of the southern High Plains. ...Southern High Plains... A potent upper low and associated 65-75 kt mid-level jet max centered over AZ are expected to quickly move eastward, overspreading the southern Rockies/High Plains this afternoon and evening. At the surface, sustained southerly flow ahead of a deepening surface low and trailing cold front over western NM will support moderate destabilization (MLCAPE 1500-2000 J/kg) with afternoon heating and continued low-level upslope. As the mid-level system approaches, mid-level height falls and flow aloft will intensify, elongating low and mid-level hodographs, allowing for convective development/organization in the form of supercells. One source of continued uncertainty is the ongoing elevated convection and cloud debris centered north of a diffuse surface boundary stretching from central NM to the western TX Panhandle. So far, this boundary has been slowly lifting north with pronounced low-level theta-e advection taking place to the south. As deep-layer ascent intensifies through the late morning, continued convective development to the north may support reinforcement and stalling of the boundary. The northward extent of destabilization remains unclear, though this boundary could serve as a focus for renewed development of more robust convection expected later this afternoon. Most CAM guidance shows scattered thunderstorms initiating off the higher terrain of eastern NM, or ahead of the cold front farther west by early this afternoon. These storms should quickly mature with supportive thermodynamics and kinematics, eventually spreading eastward into the TX Panhandle. The risk for large to very large hail/severe gusts will likely accompany the stronger supercells, and a threat for a couple tornadoes may be realized later this afternoon/early evening from eastern NM into parts of adjacent west TX, especially near the boundary where low-level shear may be locally enhanced. ...Upper Midwest and MO Valley... A second upper low near the international border is forecast to quickly move eastward reaching the western Great Lakes by early this evening. Weak ascent is expected ahead of a surging cold front and diffuse wave cyclone across the northern MO valley and southern MN. Surface moistening with a warm front lifting north near the IA/MN border may act as a focus for more robust convective development along the cold front late this afternoon. Increasingly orthogonal deep-layer flow and steeping low/mid-level lapse rates could support a mix of supercells and multi-cell clusters. A few of the stronger storms may pose some hail/wind threat, which should peak in intensity during the early evening. However, somewhat limited heating and the lack of broader forcing for ascent suggests storm coverage should remain isolated. ...Western PA into the Mid Atlantic... Short-wave troughing across the upper OH Valley within mid-level northwesterly flow is expected to support isolated to widely scattered thunderstorms across western PA/VA later this afternoon. Model forecast soundings with moderate buoyancy and modest deep-layer shear would imply some of the stronger storms being capable of an isolated risk for wind damage (50-60 mph) and perhaps some hail. This activity will likely diminish by early evening coincident with nocturnal cooling. ..Lyons/Goss.. 09/21/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Sat Sep 21 2024 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... No changes needed to the ongoing forecast. See discussion below for more details. ..Marsh.. 09/21/2024 .PREV DISCUSSION... /ISSUED 0156 AM CDT Sat Sep 21 2024/ ...Synopsis... Fire weather concerns will remain low across the CONUS today as a cold front brings cooler temperatures and increasing precipitation chances across much of the central/northern Plains. Brief periods of Elevated fire weather concerns will be possible across portions of New Mexico as enhanced mid-level flow rounds the western US upper low. In this region, relative humidity reductions to 15-20 percent will briefly overlap winds around 15-20 mph. Fuels across this region remain unsupportive of large-fire spread at this time with potential for additional rainfall from thunderstorm activity on Saturday. As such, no areas were included with this outlook. ...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 1118 AM CDT Sat Sep 21 2024 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... No changes needed to the ongoing forecast. See discussion below for more details. ..Marsh.. 09/21/2024 .PREV DISCUSSION... /ISSUED 0156 AM CDT Sat Sep 21 2024/ ...Synopsis... Fire weather concerns will remain low across the CONUS today as a cold front brings cooler temperatures and increasing precipitation chances across much of the central/northern Plains. Brief periods of Elevated fire weather concerns will be possible across portions of New Mexico as enhanced mid-level flow rounds the western US upper low. In this region, relative humidity reductions to 15-20 percent will briefly overlap winds around 15-20 mph. Fuels across this region remain unsupportive of large-fire spread at this time with potential for additional rainfall from thunderstorm activity on Saturday. As such, no areas were included with this outlook. ...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 0745 AM CDT Sat Sep 21 2024 Valid 211300Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Scattered severe storms capable of all hazards are possible this afternoon and evening across portions of the southern High Plains. ...Southern High Plains... Water-vapor imagery this morning shows a potent mid- to upper-level low and associated trough moving east across AZ. An associated 70-kt 500-mb speed max will round the base of the trough and move into central NM by early evening before weakening overnight as it moves into the TX Panhandle. Southerly low-level flow will maintain a fetch of seasonably rich moisture across the region today (reference 12 UTC Del Rio, TX and Midland, TX raobs; 18.3 and 14.9 g/kg lowest 100-mb mean mixing ratios, respectively). Early morning surface analysis places a cold front pushing southward over the central High Plains and this boundary will reach northeast NM and parts of the Panhandles late this afternoon/early evening. Some continuation of ongoing shower/thunderstorm activity may continue through the morning across eastern NM into the TX Panhandle, lending some uncertainty in airmass destabilization/recovery in wake of this convection. 06z model guidance (particularly the NAM) seemed to reasonably depict the low-level moisture plume emanating from the Rio Grande Valley/Edwards Plateau northwestward into the southern High Plains. Steep 700-500 mb lapse rates (7.5 to 8.0 deg C/km) sampled this morning from Albuquerque and Midland will combine with daytime heating to yield a moderately unstable airmass by afternoon across eastern NM into west TX. Increasing large-scale deep-layer ascent approaching from the west and frontal/orographic lift will likely contribute to scattered thunderstorms developing relatively early this afternoon. Forecast hodographs indicate supercells will evolve within this environment. The risk for large hail/severe gusts will likely accompany the stronger storms, and a threat for a few tornadoes may be realized later this afternoon/early evening from eastern NM into parts of adjacent west TX. ...Upper Midwest to Mid MO Valley... A northern-stream short-wave trough will continue to move eastward from southern MB/Dakotas into MN/northwest ON during the period. A surface cold front will advance into MN-western IA-southern NE by midday, before accelerating east into the Upper Great Lakes, while the trailing portion of the boundary pushes south-southeast into central KS by early to mid afternoon. This boundary will serve as the focus for potential convective development during the late afternoon, though surface heating is not expected to be particularly strong ahead of the wind shift. With the strongest forcing expected to spread across northwest ON, convection may be more isolated along the front trailing across the Upper Midwest. Even so, some hail/wind threat will exist with this activity which should peak in intensity during the early evening. ...Western PA into western VA... Weak short-wave trough will dig southeast across the upper OH Valley later this afternoon with modest mid-level northwesterly flow expected to extend across western PA/VA. This feature will encourage scattered convection later this afternoon along a frontal zone that will be draped across the Delmarva-western PA into western NY. Models suggest scattered storm coverage and forecast soundings would imply some of the stronger storms being capable of an isolated risk for wind damage (50-60 mph) and perhaps some hail. This activity will likely diminish by early evening coincident with nocturnal cooling. ..Smith/Broyles.. 09/21/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Sat Sep 21 2024 Valid 211300Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Scattered severe storms capable of all hazards are possible this afternoon and evening across portions of the southern High Plains. ...Southern High Plains... Water-vapor imagery this morning shows a potent mid- to upper-level low and associated trough moving east across AZ. An associated 70-kt 500-mb speed max will round the base of the trough and move into central NM by early evening before weakening overnight as it moves into the TX Panhandle. Southerly low-level flow will maintain a fetch of seasonably rich moisture across the region today (reference 12 UTC Del Rio, TX and Midland, TX raobs; 18.3 and 14.9 g/kg lowest 100-mb mean mixing ratios, respectively). Early morning surface analysis places a cold front pushing southward over the central High Plains and this boundary will reach northeast NM and parts of the Panhandles late this afternoon/early evening. Some continuation of ongoing shower/thunderstorm activity may continue through the morning across eastern NM into the TX Panhandle, lending some uncertainty in airmass destabilization/recovery in wake of this convection. 06z model guidance (particularly the NAM) seemed to reasonably depict the low-level moisture plume emanating from the Rio Grande Valley/Edwards Plateau northwestward into the southern High Plains. Steep 700-500 mb lapse rates (7.5 to 8.0 deg C/km) sampled this morning from Albuquerque and Midland will combine with daytime heating to yield a moderately unstable airmass by afternoon across eastern NM into west TX. Increasing large-scale deep-layer ascent approaching from the west and frontal/orographic lift will likely contribute to scattered thunderstorms developing relatively early this afternoon. Forecast hodographs indicate supercells will evolve within this environment. The risk for large hail/severe gusts will likely accompany the stronger storms, and a threat for a few tornadoes may be realized later this afternoon/early evening from eastern NM into parts of adjacent west TX. ...Upper Midwest to Mid MO Valley... A northern-stream short-wave trough will continue to move eastward from southern MB/Dakotas into MN/northwest ON during the period. A surface cold front will advance into MN-western IA-southern NE by midday, before accelerating east into the Upper Great Lakes, while the trailing portion of the boundary pushes south-southeast into central KS by early to mid afternoon. This boundary will serve as the focus for potential convective development during the late afternoon, though surface heating is not expected to be particularly strong ahead of the wind shift. With the strongest forcing expected to spread across northwest ON, convection may be more isolated along the front trailing across the Upper Midwest. Even so, some hail/wind threat will exist with this activity which should peak in intensity during the early evening. ...Western PA into western VA... Weak short-wave trough will dig southeast across the upper OH Valley later this afternoon with modest mid-level northwesterly flow expected to extend across western PA/VA. This feature will encourage scattered convection later this afternoon along a frontal zone that will be draped across the Delmarva-western PA into western NY. Models suggest scattered storm coverage and forecast soundings would imply some of the stronger storms being capable of an isolated risk for wind damage (50-60 mph) and perhaps some hail. This activity will likely diminish by early evening coincident with nocturnal cooling. ..Smith/Broyles.. 09/21/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0252 AM CDT Sat Sep 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... Forecast confidence is low during the Day 4-8 period as large spread is evident across medium range forecast guidance. Some low-end severe potential (sub-15 percent) may continue into Day 4/Tuesday over parts of the OH/TN Valleys and adjacent Appalachians as a surface cold front continue to progress east amid modest mid/upper level southwesterly flow. Thereafter, guidance suggests a cut-off upper low will develop over some part of the central section of the CONUS, though confidence is the evolution of this feature is low. Despite this uncertainty, severe potential appears low beyond Day 4/Tuesday given prior cold frontal passage and limited Gulf return flow. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... No fire weather concerns are expected on Sunday. A cool post-frontal air mass is expected across the Plains with potential for widespread precipitation. Dry conditions will continue across the southwestern US. As the upper low moves eastward across the Rockies, winds will also decrease with cooler temperatures expected across the region which will aid in keeping fire weather concerns low. ..Thornton.. 09/21/2024 ...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 0158 AM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...NO CRITICAL AREAS... ...Synopsis... No fire weather concerns are expected on Sunday. A cool post-frontal air mass is expected across the Plains with potential for widespread precipitation. Dry conditions will continue across the southwestern US. As the upper low moves eastward across the Rockies, winds will also decrease with cooler temperatures expected across the region which will aid in keeping fire weather concerns low. ..Thornton.. 09/21/2024 ...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 0156 AM CDT Sat Sep 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will remain low across the CONUS today as a cold front brings cooler temperatures and increasing precipitation chances across much of the central/northern Plains. Brief periods of Elevated fire weather concerns will be possible across portions of New Mexico as enhanced mid-level flow rounds the western US upper low. In this region, relative humidity reductions to 15-20 percent will briefly overlap winds around 15-20 mph. Fuels across this region remain unsupportive of large-fire spread at this time with potential for additional rainfall from thunderstorm activity on Saturday. As such, no areas were included with this outlook. ..Thornton.. 09/21/2024 ...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 0156 AM CDT Sat Sep 21 2024 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will remain low across the CONUS today as a cold front brings cooler temperatures and increasing precipitation chances across much of the central/northern Plains. Brief periods of Elevated fire weather concerns will be possible across portions of New Mexico as enhanced mid-level flow rounds the western US upper low. In this region, relative humidity reductions to 15-20 percent will briefly overlap winds around 15-20 mph. Fuels across this region remain unsupportive of large-fire spread at this time with potential for additional rainfall from thunderstorm activity on Saturday. As such, no areas were included with this outlook. ..Thornton.. 09/21/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Sat Sep 21 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OHIO VALLEY AND MID-SOUTH... ...SUMMARY... Isolated strong to severe thunderstorms are possible across the Ohio Valley and Mid-South region on Monday. ...Ohio Valley and Mid-South vicinity... An upper shortwave trough over the Mid-MS Valley will become absorbed within a larger-scale trough shifting east across the Plains on Monday. A belt of enhanced mid/upper level southwesterly flow will overspread the Ohio Valley/Mid-South vicinity through much of the period. At the surface, a cold front will develop south and east across the Ohio and the Mid/Lower MS Valley area. A seasonally moist airmass characterized by 60s F dewpoints will be in place ahead of the front. Areas of precipitation and cloud cover are likely from MO through the Ohio Valley early in the period, resulting in forecast uncertainty. Nevertheless, enhanced midlevel flow overspreading a moist airmass ahead of a cold front should support some risk for severe thunderstorms where greater destabilization occurs. Locally damaging gusts and hail appear to be the most likely concerns with the strongest convection Monday afternoon into the evening. ..Leitman.. 09/21/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0149 AM CDT Sat Sep 21 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OHIO VALLEY AND MID-SOUTH... ...SUMMARY... Isolated strong to severe thunderstorms are possible across the Ohio Valley and Mid-South region on Monday. ...Ohio Valley and Mid-South vicinity... An upper shortwave trough over the Mid-MS Valley will become absorbed within a larger-scale trough shifting east across the Plains on Monday. A belt of enhanced mid/upper level southwesterly flow will overspread the Ohio Valley/Mid-South vicinity through much of the period. At the surface, a cold front will develop south and east across the Ohio and the Mid/Lower MS Valley area. A seasonally moist airmass characterized by 60s F dewpoints will be in place ahead of the front. Areas of precipitation and cloud cover are likely from MO through the Ohio Valley early in the period, resulting in forecast uncertainty. Nevertheless, enhanced midlevel flow overspreading a moist airmass ahead of a cold front should support some risk for severe thunderstorms where greater destabilization occurs. Locally damaging gusts and hail appear to be the most likely concerns with the strongest convection Monday afternoon into the evening. ..Leitman.. 09/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1213 AM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WEST TEXAS INTO CENTRAL/SOUTHERN MISSOURI... ...SUMMARY... Isolated severe thunderstorms are possible on Sunday from west Texas to central/southern Missouri. ...Southern Plains to Mid-MS Valley... Forecast guidance has trended somewhat southward with severe potential on Sunday, and the Marginal risk (level 1 of 5) has been adjusted to reflect latest model trends. An upper shortwave trough over the central/southern Rockies Sunday morning will eject east to the mid-MS Valley by Monday morning. This will bring a belt of 40-50 kt mid/upper southwesterly flow over the region. At the surface, a cold front will develop southeast from near Lake Michigan to northwest Texas at midday to the Ohio Valley and central Texas by 12z Monday. A seasonally moist airmass will be in place ahead of the front, with surface dewpoints in the mid to upper 60s F forecast. Some uncertainty remains in where the corridor of greater strong/severe storm potential will develop, mainly driven by ongoing convection across parts of the region Sunday morning. Nevertheless, where pockets of greater heating occur, favorable vertical shear and increasing forcing from both the surface front and the ejecting midlevel wave, will support organized storm development. Damaging gusts will be the main hazard with thunderstorm clusters and line segments. However, vertical shear may be suitable for a few supercells, especially across west Texas. Isolated large hail will be possible with any more discrete cells that develop and can be maintained ahead of the front. ..Leitman.. 09/21/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1213 AM CDT Sat Sep 21 2024 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WEST TEXAS INTO CENTRAL/SOUTHERN MISSOURI... ...SUMMARY... Isolated severe thunderstorms are possible on Sunday from west Texas to central/southern Missouri. ...Southern Plains to Mid-MS Valley... Forecast guidance has trended somewhat southward with severe potential on Sunday, and the Marginal risk (level 1 of 5) has been adjusted to reflect latest model trends. An upper shortwave trough over the central/southern Rockies Sunday morning will eject east to the mid-MS Valley by Monday morning. This will bring a belt of 40-50 kt mid/upper southwesterly flow over the region. At the surface, a cold front will develop southeast from near Lake Michigan to northwest Texas at midday to the Ohio Valley and central Texas by 12z Monday. A seasonally moist airmass will be in place ahead of the front, with surface dewpoints in the mid to upper 60s F forecast. Some uncertainty remains in where the corridor of greater strong/severe storm potential will develop, mainly driven by ongoing convection across parts of the region Sunday morning. Nevertheless, where pockets of greater heating occur, favorable vertical shear and increasing forcing from both the surface front and the ejecting midlevel wave, will support organized storm development. Damaging gusts will be the main hazard with thunderstorm clusters and line segments. However, vertical shear may be suitable for a few supercells, especially across west Texas. Isolated large hail will be possible with any more discrete cells that develop and can be maintained ahead of the front. ..Leitman.. 09/21/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Sat Sep 21 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN HIGH PLAINS... ...SUMMARY... Scattered severe storms are expected this afternoon and evening across the southern High Plains. Isolated strong to severe thunderstorms are also possible from the mid Missouri Valley to the Upper Midwest, and also from western Pennsylvania into northern/central Virginia. ...Southern High Plains... Notable upper trough has advanced into the lower CO River Valley early this morning. Strong 500mb speed max will soon round the base of the trough and eject across southern AZ into southern NM by late afternoon. This feature will greatly influence convective development/intensity across the southern High Plains by peak heating. Northern-stream short-wave trough will shift east today which will allow a sharp surface cold front to surge south across the High Plains into eastern CO by early afternoon, likely arcing across the northern TX Panhandle into northeast NM by 22/00z. Strong boundary-layer heating is expected across southern NM with more modest warming forecast within southeasterly upslope flow from the TX/NM border into the Sangre de Cristo range, just southwest of the cold front. Forecast soundings suggest convective temperatures will be breached fairly early, aided in part by frontal/orographic influences. Scattered convection will easily develop ahead of the short wave, and this activity will be strongly sheared as the speed max approaches. Supercells are expected to evolve within this environment as 0-6km shear will be on the order of 50kt, along with veering winds with height. Large hail should develop with this activity along with some risk for a few tornadoes. ...Upper Midwest to Mid MO Valley... Northern-stream short-wave trough is progressing across SK/eastern MT into the northern Plains, in line with latest model guidance. This feature is forecast to suppress the height field immediately downstream across eastern ND into northern MN, though the strongest falls will remain north of the international border. Even so, notable surface front will advance into MN-western IA-southern NE by 18z, then steadily surge east into the early evening hours. This boundary will serve as the focus for potential convective development during the late afternoon, though surface heating is not expected to be particularly strong ahead of the wind shift. With the strongest forcing expected to spread across northwest ON, convection may be more isolated along the front trailing across the Upper Midwest. Even so, some hail/wind threat will exist with this activity which should peak in intensity during the early evening. ...Western PA into western VA... Weak short-wave trough will dig southeast across the upper OH Valley later this afternoon with modest mid-level northwesterly flow expected to extend across western PA/VA. This feature will encourage scattered convection later this afternoon along a frontal zone that will be draped across the Delmarva-western PA into western NY. Convection that evolves near this wind shift will move southeast with an attendant risk for gusty winds and some hail. ..Darrow/Thornton.. 09/21/2024 Read more