Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0433 PM CDT Sun Aug 24 2025 Valid 261200Z - 011200Z Upper-level troughing is likely to continue over much of the West this week but weaken from its peak this weekend. Weak upper-level troughing is forecast to develop off the West Coast through mid-week with an upper-level trough likely to approach the Northwest Day 5/Thursday. Monsoonal moisture will continue to push northward through the Northwest and the Northern Rockies by Day 5/Thursday. Daily wet thunderstorms and showers remain likely for much of the southern/central Intermountain West, with wet thunderstorms and wetting rain moving into central/north Idaho and western Montana Day 4/Wednesday - Day 5/Thursday. Drier air will begin to filter into the West behind this monsoonal surge, mostly from west to east mid to late week. Mixed wet/dry thunderstorms over receptive fuels are possible in portions of the Cascades, especially from northern Oregon northward, and northern Rockies mainly north Idaho and northwest Montana. Additionally, as drier air filters into portions of California and the Great Basin, areas will be monitored for potential introduction of dry thunderstorm probabilities. The main reason for not including probabilities at this time is the uncertainty regarding the spatial extent and magnitude of ongoing/upcoming wetting rain coupled with thunderstorm chances away from these areas. ..Nauslar.. 08/24/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2009 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN COLORADO TO SOUTHWEST KANSAS
Mesoscale Discussion 2009 NWS Storm Prediction Center Norman OK 0246 PM CDT Sun Aug 24 2025 Areas affected...Eastern Colorado to southwest Kansas Concerning...Severe potential...Watch unlikely Valid 241946Z - 242145Z Probability of Watch Issuance...20 percent SUMMARY...An isolated supercell or two appears possible this afternoon across eastern Colorado to southwest Kansas. Large hail, and perhaps a tornado, will be possible. DISCUSSION...Latest GOES imagery show steady vertical development of convective towers near the intersection of a diffuse warm front draped across eastern CO and a decaying outflow boundary from morning convection. Temperatures warming into the upper 70s and low 80s continue to erode lingering MLCIN in the vicinity of the boundary intersection, which should help increase the probability of sustained convection in the coming hours. While it remains unclear how many thunderstorms will emerge from this zone due to weak forcing for ascent, the downstream environment is becoming increasingly favorable for supercells with MLCAPE increasing to around 1500 J/kg and deep-layer wind shear on the order of 35-45 knots in the vicinity of the boundary. Additionally, backed winds on the cool side of the boundary (where temperatures are quickly recovering) may support locally-enhanced low-level SRH and/or augmented low-level vertical vorticity on the boundary itself. Consequently, it is conceivable that a supercell could propagate along the boundary to the southeast with an attendant threat for large hail (possibly as large as 2.5 inches) and perhaps a tornado. Watch issuance is not imminent due to uncertainty regarding storm coverage, but convective trends will continue to be monitored through this corridor. ..Moore/Gleason.. 08/24/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DDC...GLD...PUB...BOU... LAT...LON 38920363 39240385 39650373 39810340 39840299 39050173 38120083 37760080 37520111 37320146 37350181 37500212 38920363 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN Read more

WW 0602 Status Updates
STATUS FOR WATCH 0602 HAS NOT BEEN ISSUED YET Read more

WW 0602 Status Updates
STATUS FOR WATCH 0602 HAS NOT BEEN ISSUED YET Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Aug 24 2025 Valid 242000Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN COLORADO INTO FAR SOUTHWESTERN KANSAS AND PORTIONS OF THE OKLAHOMA PANHANDLE... ...SUMMARY... A few severe thunderstorms are expected this afternoon and evening across the southern/central High Plains spanning from eastern Colorado into western Oklahoma. Scattered strong to severe thunderstorms are also possible across portions of Pennsylvania and New York. ...20z Update... An upgrade to Slight was made with this update in eastern Colorado/western Kansas. Thermodynamics and shear profiles are favorable for supercell development. Recent development on radar suggests attempts are ongoing across portions of eastern Colorado near the Palmer Divide and near Colorado Springs. Any more discrete supercells that can be maintained will pose a risk for large hail, and as such a 15% was added with this update. See MCD#2009 for more information. ..Thornton.. 08/24/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 24 2025/ ...Southern/Central High Plains... Elevated thunderstorms are ongoing late this morning across parts of western/southern KS in a northwesterly mid-level flow regime. This activity has generally remained sub-severe, but the stronger cores could be capable of producing occasional hail as they track southeastward this afternoon given the presence of sufficient MUCAPE and deep-layer shear. Modestly enhanced mid-level flow is expected to remain over parts of the central into southern Plains today, generally from eastern WY/CO into western KS/OK and vicinity, between a mid/upper-level anticyclone over the Southwest and mid/upper-level troughing across the Upper Midwest. A surface front extends from northern CO into western KS. This boundary, along with outflow from ongoing convection, may serve as foci for robust thunderstorm development later today. There is still a fair amount of uncertainty regarding convective development and evolution this afternoon/evening across the southern/central High Plains given weak forcing aloft. Modest low-level upslope flow and orographic effects should encourage at least isolated thunderstorms to initially develop over the higher terrain of the central Rockies/Front Range, and subsequently spread southeastward into the High Plains through the evening. The front/outflow boundary draped from northeast CO into southwest KS could also serve as a forcing mechanism to aid parcels in reaching their LFCs. The environment along/south of the front should become moderately unstable with continued daytime heating, with greater low-level moisture present across western KS into the OK/TX Panhandles and western OK. Modest low-level southeasterlies should persist through much of the afternoon/evening along and near the front, which should locally enhance 0-1 km SRH. It appears possible that a supercell or two could develop near the front later today and track south-southeastward in a favorable northwesterly mid-level flow regime. Isolated large hail would probably be the main threat if a supercell can be sustained, with perhaps a tornado also possible where low-level flow can remain backed to southeasterly near the front. Some guidance suggests a cluster or two may eventually emerge this evening across eastern CO and/or southwest KS, but this potential remains highly uncertain. Mesoscale trends will be monitored for a zone of more focused severe potential and possible outlook upgrade. ...New York/Pennsylvania... An amplified upper trough/low over Ontario and extending southward into the Great Lakes/Midwest is forecast to gradually shift eastward today. A related surface cold front will also advance east-southeastward through the period across parts of the Northeast and Mid-Atlantic/OH Valley. Filtered daytime heating of a modestly moist low-level airmass ahead of the front will promote weak to locally moderate instability this afternoon, especially across parts of PA/NY. Current expectations are for thunderstorms to develop along/near the front through the afternoon across western PA/NY. While mid-level lapse rates are forecast to remain poor, which will likely limit updraft strength, sufficient deep-layer shear should be present to support some thunderstorm organization. Loosely organized clusters/cells may pose an isolated threat for damaging winds and perhaps marginally severe hail as they spread eastward across central PA and central/northern NY through early evening. This activity should weaken with eastward extent as it encounters a less unstable airmass. Read more