Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Fri Jul 19 2024 Valid 191630Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR WESTERN KANSAS INTO SOUTHWEST NEBRASKA AND EXTREME EASTERN COLORADO... ...SUMMARY... Scattered to numerous severe gusts (60-75 mph) are possible this afternoon into tonight across portions of the central Great Plains. ...Central/southern Great Plains... Visible-satellite imagery late this morning shows several clusters of sub-severe thunderstorms over central/northern NE into SD ahead of a southeastward-migrating mid-level shortwave impulse. The disturbance is evident in water-vapor imagery and approaching the Black Hills vicinity. The mid- to upper-level anticyclone over the Great Basin/Desert Southwest will move little during the period, and aid in allowing the aforementioned disturbance to move southeastward into eastern NE/western IA later tonight. Morning surface analysis places a moist axis from western KS northward into west-central NE and SD with lower 60s deg F surface dewpoints. This adequately moist airmass will become moderately unstable by mid afternoon across southwest NE southward into extreme eastern CO and western KS (2000-2500 J/kg MLCAPE). It seems plausible a southward-moving cluster will emerge from the midday ongoing thunderstorm activity over central NE and move into a boundary layer featuring steep 0-3 km lapse rates. Veering flow with height will support 35-45 kt effective shear and promote storm organization. Large hail and severe gusts will be possible with the stronger storms over mainly parts of NE and SD. As additional storms develop, a coalescing into one or more clusters will likely evolve by late afternoon over the central Great Plains. Additionally, scattered storm development is expected near/east of the Front Range with coverage forecast to increase as storms move into a more moist environment over eastern CO. Upscale growth into one or more linear clusters is expected before an MCS evolves (perhaps from a merging of thunderstorm clusters) over western KS by this evening. Severe gusts will be the primary hazard later this afternoon through the late evening. As storms move farther southwest into central KS and parts of northwest OK/TX Panhandle later this evening, weaker instability and greater CINH will likely lead to a gradual decrease in storm intensity and severe risk. ..Smith/Squitieri.. 07/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Fri Jul 19 2024 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHWESTERN/SOUTH-CENTRAL NEBRASKA ACROSS WESTERN KANSAS AND EXTREME EASTERN COLORADO... ...SUMMARY... The most favorable corridor for damaging thunderstorm gusts (some potentially exceeding 70 mph) will be late this afternoon and evening from parts of southwestern/south-central Nebraska across western Kansas and extreme eastern Colorado. ...Synopsis... A large anticyclone in mid/upper levels -- initially centered over north-central/northeastern AZ -- is forecast to retrograde northwestward over more of the Great Basin today. This will result in northwesterly flow over the northern Great Plains, and substantially northerly mid/upper flow over most of the rest of the Plains States, in conjunction with the persistent eastern CONUS longwave trough. Within that regime, a shortwave trough now located over eastern MT is expected to move southeastward to southern SD and northern NE by 00Z. Overnight, this feature may phase with another, weaker trough to its east, as well as take on convectively generated vorticity, and move over eastern NE/IA and vicinity. At the surface, a weak, slow-moving frontal zone (cold or warm on various mesoscale segments) was analyzed at 11Z from the Hampton Roads area across northern parts of GA/AL/MS/LA, becoming diffuse over central/north TX. Richest maritime/tropical moisture was (and will remain) confined along and south of that boundary through the period. However, a corridor of relatively maximized moisture, with dewpoints upper 50s to low 60s F -- was analyzed from the central Dakotas to western/central NE and western KS, with some eastward shifting/erosion possible on the west side today as heating/mixing occur. A lee trough should remain over the High Plains from eastern MT to the western NE Panhandle and eastern CO, to eastern NM. A trough now over parts of central SD into northwestern NE, to a low at the intersection of the troughs near BFF, potentially will become better defined and shifting southeast amid mass response to the approaching perturbation aloft. ...Central/southern Great Plains... Isolated to scattered thunderstorms are expected to develop this afternoon over both the Front Range/Foothills corridor of CO and southeastern WY, and near a surface trough across northern/central NE. Damaging gusts and large hail will be possible with early-stage activity over NE, with gusts the more probable hazard in the CO convection. Activity should evolve upscale in both areas, moving southeastward over CO and generally southward with some westward backbuilding over central NE to western KS. An MCS with organizing cold pool appears increasingly probable, with one or more associated swaths of severe gusts expected. The best-organized and most-intense severe-wind potential may begin sooner and farther north, and conditionally may persist farther south before overnight weakening, than depicted in the "enhanced"/ 30%-wind area. However, a preponderance of guidance -- reasonably, given the overall pattern and placement of the moisture/instability corridor -- has settled on the area from southwestern NE southward across western KS to near the OK Panhandle as a most-probable corridor for severe gusts. At least isolated significant-severe (65+ kt) gusts also may be observed. Enough vertical shear will be present to support supercell potential with any relatively discrete convection in the early stages, as strong veering with height contributes to 30-45-kt effective-shear magnitudes, despite lacking stronger midlevel winds. Activity over CO will be in weaker (but still sufficient) low-level moisture and higher-based. However, even near the moist axis over central NE and western KS, a deeply well-mixed boundary layer will support wind potential. Strong surface heating should help to boost MLCAPE to 2000-2500 J/kg over much of central/west-central NE, and 1500-2000 J/kg over western KS. Activity moving into eastern NE into central KS will encounter weaker instability and greater CINH, limiting eastward extent of the severe threat, while nocturnal cooling and related stabilization will decrease the threat southward into northwestern OK and the Panhandles. How far the severe-gust threat penetrates into that stabilizing air will depend largely on strength of cold-pool-driven forced ascent and associated downdraft production, driven by low-predictability internal dynamics of the complex. ..Edwards/Broyles.. 07/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Fri Jul 19 2024 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHWESTERN/SOUTH-CENTRAL NEBRASKA ACROSS WESTERN KANSAS AND EXTREME EASTERN COLORADO... ...SUMMARY... The most favorable corridor for damaging thunderstorm gusts (some potentially exceeding 70 mph) will be late this afternoon and evening from parts of southwestern/south-central Nebraska across western Kansas and extreme eastern Colorado. ...Synopsis... A large anticyclone in mid/upper levels -- initially centered over north-central/northeastern AZ -- is forecast to retrograde northwestward over more of the Great Basin today. This will result in northwesterly flow over the northern Great Plains, and substantially northerly mid/upper flow over most of the rest of the Plains States, in conjunction with the persistent eastern CONUS longwave trough. Within that regime, a shortwave trough now located over eastern MT is expected to move southeastward to southern SD and northern NE by 00Z. Overnight, this feature may phase with another, weaker trough to its east, as well as take on convectively generated vorticity, and move over eastern NE/IA and vicinity. At the surface, a weak, slow-moving frontal zone (cold or warm on various mesoscale segments) was analyzed at 11Z from the Hampton Roads area across northern parts of GA/AL/MS/LA, becoming diffuse over central/north TX. Richest maritime/tropical moisture was (and will remain) confined along and south of that boundary through the period. However, a corridor of relatively maximized moisture, with dewpoints upper 50s to low 60s F -- was analyzed from the central Dakotas to western/central NE and western KS, with some eastward shifting/erosion possible on the west side today as heating/mixing occur. A lee trough should remain over the High Plains from eastern MT to the western NE Panhandle and eastern CO, to eastern NM. A trough now over parts of central SD into northwestern NE, to a low at the intersection of the troughs near BFF, potentially will become better defined and shifting southeast amid mass response to the approaching perturbation aloft. ...Central/southern Great Plains... Isolated to scattered thunderstorms are expected to develop this afternoon over both the Front Range/Foothills corridor of CO and southeastern WY, and near a surface trough across northern/central NE. Damaging gusts and large hail will be possible with early-stage activity over NE, with gusts the more probable hazard in the CO convection. Activity should evolve upscale in both areas, moving southeastward over CO and generally southward with some westward backbuilding over central NE to western KS. An MCS with organizing cold pool appears increasingly probable, with one or more associated swaths of severe gusts expected. The best-organized and most-intense severe-wind potential may begin sooner and farther north, and conditionally may persist farther south before overnight weakening, than depicted in the "enhanced"/ 30%-wind area. However, a preponderance of guidance -- reasonably, given the overall pattern and placement of the moisture/instability corridor -- has settled on the area from southwestern NE southward across western KS to near the OK Panhandle as a most-probable corridor for severe gusts. At least isolated significant-severe (65+ kt) gusts also may be observed. Enough vertical shear will be present to support supercell potential with any relatively discrete convection in the early stages, as strong veering with height contributes to 30-45-kt effective-shear magnitudes, despite lacking stronger midlevel winds. Activity over CO will be in weaker (but still sufficient) low-level moisture and higher-based. However, even near the moist axis over central NE and western KS, a deeply well-mixed boundary layer will support wind potential. Strong surface heating should help to boost MLCAPE to 2000-2500 J/kg over much of central/west-central NE, and 1500-2000 J/kg over western KS. Activity moving into eastern NE into central KS will encounter weaker instability and greater CINH, limiting eastward extent of the severe threat, while nocturnal cooling and related stabilization will decrease the threat southward into northwestern OK and the Panhandles. How far the severe-gust threat penetrates into that stabilizing air will depend largely on strength of cold-pool-driven forced ascent and associated downdraft production, driven by low-predictability internal dynamics of the complex. ..Edwards/Broyles.. 07/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Fri Jul 19 2024 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHWESTERN/SOUTH-CENTRAL NEBRASKA ACROSS WESTERN KANSAS AND EXTREME EASTERN COLORADO... ...SUMMARY... The most favorable corridor for damaging thunderstorm gusts (some potentially exceeding 70 mph) will be late this afternoon and evening from parts of southwestern/south-central Nebraska across western Kansas and extreme eastern Colorado. ...Synopsis... A large anticyclone in mid/upper levels -- initially centered over north-central/northeastern AZ -- is forecast to retrograde northwestward over more of the Great Basin today. This will result in northwesterly flow over the northern Great Plains, and substantially northerly mid/upper flow over most of the rest of the Plains States, in conjunction with the persistent eastern CONUS longwave trough. Within that regime, a shortwave trough now located over eastern MT is expected to move southeastward to southern SD and northern NE by 00Z. Overnight, this feature may phase with another, weaker trough to its east, as well as take on convectively generated vorticity, and move over eastern NE/IA and vicinity. At the surface, a weak, slow-moving frontal zone (cold or warm on various mesoscale segments) was analyzed at 11Z from the Hampton Roads area across northern parts of GA/AL/MS/LA, becoming diffuse over central/north TX. Richest maritime/tropical moisture was (and will remain) confined along and south of that boundary through the period. However, a corridor of relatively maximized moisture, with dewpoints upper 50s to low 60s F -- was analyzed from the central Dakotas to western/central NE and western KS, with some eastward shifting/erosion possible on the west side today as heating/mixing occur. A lee trough should remain over the High Plains from eastern MT to the western NE Panhandle and eastern CO, to eastern NM. A trough now over parts of central SD into northwestern NE, to a low at the intersection of the troughs near BFF, potentially will become better defined and shifting southeast amid mass response to the approaching perturbation aloft. ...Central/southern Great Plains... Isolated to scattered thunderstorms are expected to develop this afternoon over both the Front Range/Foothills corridor of CO and southeastern WY, and near a surface trough across northern/central NE. Damaging gusts and large hail will be possible with early-stage activity over NE, with gusts the more probable hazard in the CO convection. Activity should evolve upscale in both areas, moving southeastward over CO and generally southward with some westward backbuilding over central NE to western KS. An MCS with organizing cold pool appears increasingly probable, with one or more associated swaths of severe gusts expected. The best-organized and most-intense severe-wind potential may begin sooner and farther north, and conditionally may persist farther south before overnight weakening, than depicted in the "enhanced"/ 30%-wind area. However, a preponderance of guidance -- reasonably, given the overall pattern and placement of the moisture/instability corridor -- has settled on the area from southwestern NE southward across western KS to near the OK Panhandle as a most-probable corridor for severe gusts. At least isolated significant-severe (65+ kt) gusts also may be observed. Enough vertical shear will be present to support supercell potential with any relatively discrete convection in the early stages, as strong veering with height contributes to 30-45-kt effective-shear magnitudes, despite lacking stronger midlevel winds. Activity over CO will be in weaker (but still sufficient) low-level moisture and higher-based. However, even near the moist axis over central NE and western KS, a deeply well-mixed boundary layer will support wind potential. Strong surface heating should help to boost MLCAPE to 2000-2500 J/kg over much of central/west-central NE, and 1500-2000 J/kg over western KS. Activity moving into eastern NE into central KS will encounter weaker instability and greater CINH, limiting eastward extent of the severe threat, while nocturnal cooling and related stabilization will decrease the threat southward into northwestern OK and the Panhandles. How far the severe-gust threat penetrates into that stabilizing air will depend largely on strength of cold-pool-driven forced ascent and associated downdraft production, driven by low-predictability internal dynamics of the complex. ..Edwards/Broyles.. 07/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Fri Jul 19 2024 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHWESTERN/SOUTH-CENTRAL NEBRASKA ACROSS WESTERN KANSAS AND EXTREME EASTERN COLORADO... ...SUMMARY... The most favorable corridor for damaging thunderstorm gusts (some potentially exceeding 70 mph) will be late this afternoon and evening from parts of southwestern/south-central Nebraska across western Kansas and extreme eastern Colorado. ...Synopsis... A large anticyclone in mid/upper levels -- initially centered over north-central/northeastern AZ -- is forecast to retrograde northwestward over more of the Great Basin today. This will result in northwesterly flow over the northern Great Plains, and substantially northerly mid/upper flow over most of the rest of the Plains States, in conjunction with the persistent eastern CONUS longwave trough. Within that regime, a shortwave trough now located over eastern MT is expected to move southeastward to southern SD and northern NE by 00Z. Overnight, this feature may phase with another, weaker trough to its east, as well as take on convectively generated vorticity, and move over eastern NE/IA and vicinity. At the surface, a weak, slow-moving frontal zone (cold or warm on various mesoscale segments) was analyzed at 11Z from the Hampton Roads area across northern parts of GA/AL/MS/LA, becoming diffuse over central/north TX. Richest maritime/tropical moisture was (and will remain) confined along and south of that boundary through the period. However, a corridor of relatively maximized moisture, with dewpoints upper 50s to low 60s F -- was analyzed from the central Dakotas to western/central NE and western KS, with some eastward shifting/erosion possible on the west side today as heating/mixing occur. A lee trough should remain over the High Plains from eastern MT to the western NE Panhandle and eastern CO, to eastern NM. A trough now over parts of central SD into northwestern NE, to a low at the intersection of the troughs near BFF, potentially will become better defined and shifting southeast amid mass response to the approaching perturbation aloft. ...Central/southern Great Plains... Isolated to scattered thunderstorms are expected to develop this afternoon over both the Front Range/Foothills corridor of CO and southeastern WY, and near a surface trough across northern/central NE. Damaging gusts and large hail will be possible with early-stage activity over NE, with gusts the more probable hazard in the CO convection. Activity should evolve upscale in both areas, moving southeastward over CO and generally southward with some westward backbuilding over central NE to western KS. An MCS with organizing cold pool appears increasingly probable, with one or more associated swaths of severe gusts expected. The best-organized and most-intense severe-wind potential may begin sooner and farther north, and conditionally may persist farther south before overnight weakening, than depicted in the "enhanced"/ 30%-wind area. However, a preponderance of guidance -- reasonably, given the overall pattern and placement of the moisture/instability corridor -- has settled on the area from southwestern NE southward across western KS to near the OK Panhandle as a most-probable corridor for severe gusts. At least isolated significant-severe (65+ kt) gusts also may be observed. Enough vertical shear will be present to support supercell potential with any relatively discrete convection in the early stages, as strong veering with height contributes to 30-45-kt effective-shear magnitudes, despite lacking stronger midlevel winds. Activity over CO will be in weaker (but still sufficient) low-level moisture and higher-based. However, even near the moist axis over central NE and western KS, a deeply well-mixed boundary layer will support wind potential. Strong surface heating should help to boost MLCAPE to 2000-2500 J/kg over much of central/west-central NE, and 1500-2000 J/kg over western KS. Activity moving into eastern NE into central KS will encounter weaker instability and greater CINH, limiting eastward extent of the severe threat, while nocturnal cooling and related stabilization will decrease the threat southward into northwestern OK and the Panhandles. How far the severe-gust threat penetrates into that stabilizing air will depend largely on strength of cold-pool-driven forced ascent and associated downdraft production, driven by low-predictability internal dynamics of the complex. ..Edwards/Broyles.. 07/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Fri Jul 19 2024 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHWESTERN/SOUTH-CENTRAL NEBRASKA ACROSS WESTERN KANSAS AND EXTREME EASTERN COLORADO... ...SUMMARY... The most favorable corridor for damaging thunderstorm gusts (some potentially exceeding 70 mph) will be late this afternoon and evening from parts of southwestern/south-central Nebraska across western Kansas and extreme eastern Colorado. ...Synopsis... A large anticyclone in mid/upper levels -- initially centered over north-central/northeastern AZ -- is forecast to retrograde northwestward over more of the Great Basin today. This will result in northwesterly flow over the northern Great Plains, and substantially northerly mid/upper flow over most of the rest of the Plains States, in conjunction with the persistent eastern CONUS longwave trough. Within that regime, a shortwave trough now located over eastern MT is expected to move southeastward to southern SD and northern NE by 00Z. Overnight, this feature may phase with another, weaker trough to its east, as well as take on convectively generated vorticity, and move over eastern NE/IA and vicinity. At the surface, a weak, slow-moving frontal zone (cold or warm on various mesoscale segments) was analyzed at 11Z from the Hampton Roads area across northern parts of GA/AL/MS/LA, becoming diffuse over central/north TX. Richest maritime/tropical moisture was (and will remain) confined along and south of that boundary through the period. However, a corridor of relatively maximized moisture, with dewpoints upper 50s to low 60s F -- was analyzed from the central Dakotas to western/central NE and western KS, with some eastward shifting/erosion possible on the west side today as heating/mixing occur. A lee trough should remain over the High Plains from eastern MT to the western NE Panhandle and eastern CO, to eastern NM. A trough now over parts of central SD into northwestern NE, to a low at the intersection of the troughs near BFF, potentially will become better defined and shifting southeast amid mass response to the approaching perturbation aloft. ...Central/southern Great Plains... Isolated to scattered thunderstorms are expected to develop this afternoon over both the Front Range/Foothills corridor of CO and southeastern WY, and near a surface trough across northern/central NE. Damaging gusts and large hail will be possible with early-stage activity over NE, with gusts the more probable hazard in the CO convection. Activity should evolve upscale in both areas, moving southeastward over CO and generally southward with some westward backbuilding over central NE to western KS. An MCS with organizing cold pool appears increasingly probable, with one or more associated swaths of severe gusts expected. The best-organized and most-intense severe-wind potential may begin sooner and farther north, and conditionally may persist farther south before overnight weakening, than depicted in the "enhanced"/ 30%-wind area. However, a preponderance of guidance -- reasonably, given the overall pattern and placement of the moisture/instability corridor -- has settled on the area from southwestern NE southward across western KS to near the OK Panhandle as a most-probable corridor for severe gusts. At least isolated significant-severe (65+ kt) gusts also may be observed. Enough vertical shear will be present to support supercell potential with any relatively discrete convection in the early stages, as strong veering with height contributes to 30-45-kt effective-shear magnitudes, despite lacking stronger midlevel winds. Activity over CO will be in weaker (but still sufficient) low-level moisture and higher-based. However, even near the moist axis over central NE and western KS, a deeply well-mixed boundary layer will support wind potential. Strong surface heating should help to boost MLCAPE to 2000-2500 J/kg over much of central/west-central NE, and 1500-2000 J/kg over western KS. Activity moving into eastern NE into central KS will encounter weaker instability and greater CINH, limiting eastward extent of the severe threat, while nocturnal cooling and related stabilization will decrease the threat southward into northwestern OK and the Panhandles. How far the severe-gust threat penetrates into that stabilizing air will depend largely on strength of cold-pool-driven forced ascent and associated downdraft production, driven by low-predictability internal dynamics of the complex. ..Edwards/Broyles.. 07/19/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Fri Jul 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... The overall pattern will not change much during the Day 4-8 period. An upper ridge over the western states will gradually shift east into the Plains around Days 7-8/Thu-Fri. Meanwhile, a mean upper trough will persist across the eastern U.S., with some eastward progression of an embedded shortwave trough from the upper Great Lakes toward the Northeast around mid to late week. Mid/upper flow will remain modest. Given an overall stagnant upper pattern, a somewhat nondescript surface pattern lacking any appreciable cyclogenesis is forecast. While a typically moist and unstable summertime airmass will be in place east of the Rockies, severe-thunderstorm chances appear low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Fri Jul 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... The overall pattern will not change much during the Day 4-8 period. An upper ridge over the western states will gradually shift east into the Plains around Days 7-8/Thu-Fri. Meanwhile, a mean upper trough will persist across the eastern U.S., with some eastward progression of an embedded shortwave trough from the upper Great Lakes toward the Northeast around mid to late week. Mid/upper flow will remain modest. Given an overall stagnant upper pattern, a somewhat nondescript surface pattern lacking any appreciable cyclogenesis is forecast. While a typically moist and unstable summertime airmass will be in place east of the Rockies, severe-thunderstorm chances appear low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Fri Jul 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... The overall pattern will not change much during the Day 4-8 period. An upper ridge over the western states will gradually shift east into the Plains around Days 7-8/Thu-Fri. Meanwhile, a mean upper trough will persist across the eastern U.S., with some eastward progression of an embedded shortwave trough from the upper Great Lakes toward the Northeast around mid to late week. Mid/upper flow will remain modest. Given an overall stagnant upper pattern, a somewhat nondescript surface pattern lacking any appreciable cyclogenesis is forecast. While a typically moist and unstable summertime airmass will be in place east of the Rockies, severe-thunderstorm chances appear low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Fri Jul 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... The overall pattern will not change much during the Day 4-8 period. An upper ridge over the western states will gradually shift east into the Plains around Days 7-8/Thu-Fri. Meanwhile, a mean upper trough will persist across the eastern U.S., with some eastward progression of an embedded shortwave trough from the upper Great Lakes toward the Northeast around mid to late week. Mid/upper flow will remain modest. Given an overall stagnant upper pattern, a somewhat nondescript surface pattern lacking any appreciable cyclogenesis is forecast. While a typically moist and unstable summertime airmass will be in place east of the Rockies, severe-thunderstorm chances appear low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0349 AM CDT Fri Jul 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... The overall pattern will not change much during the Day 4-8 period. An upper ridge over the western states will gradually shift east into the Plains around Days 7-8/Thu-Fri. Meanwhile, a mean upper trough will persist across the eastern U.S., with some eastward progression of an embedded shortwave trough from the upper Great Lakes toward the Northeast around mid to late week. Mid/upper flow will remain modest. Given an overall stagnant upper pattern, a somewhat nondescript surface pattern lacking any appreciable cyclogenesis is forecast. While a typically moist and unstable summertime airmass will be in place east of the Rockies, severe-thunderstorm chances appear low. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Fri Jul 19 2024 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-thunderstorm potential is expected to be low on Sunday. ...Synopsis... An upper ridge will persist over the western states on Sunday. Further east, broad upper troughing will envelop the central/eastern portions of the U.S. Weak mid/upper flow also is expected, limiting vertical shear. At the surface, high pressure will generally extent east from the Great Lakes to the Northeast. A seasonally moist airmass will extend from the southern Plains through the Mid-South/Southeast and Mid-Atlantic. Scattered thunderstorm activity is expected, but organized severe potential appears low given aforementioned weak deep-layer flow/vertical shear, and a lack of any stronger large-scale ascent. ..Leitman.. 07/19/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Fri Jul 19 2024 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-thunderstorm potential is expected to be low on Sunday. ...Synopsis... An upper ridge will persist over the western states on Sunday. Further east, broad upper troughing will envelop the central/eastern portions of the U.S. Weak mid/upper flow also is expected, limiting vertical shear. At the surface, high pressure will generally extent east from the Great Lakes to the Northeast. A seasonally moist airmass will extend from the southern Plains through the Mid-South/Southeast and Mid-Atlantic. Scattered thunderstorm activity is expected, but organized severe potential appears low given aforementioned weak deep-layer flow/vertical shear, and a lack of any stronger large-scale ascent. ..Leitman.. 07/19/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Fri Jul 19 2024 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-thunderstorm potential is expected to be low on Sunday. ...Synopsis... An upper ridge will persist over the western states on Sunday. Further east, broad upper troughing will envelop the central/eastern portions of the U.S. Weak mid/upper flow also is expected, limiting vertical shear. At the surface, high pressure will generally extent east from the Great Lakes to the Northeast. A seasonally moist airmass will extend from the southern Plains through the Mid-South/Southeast and Mid-Atlantic. Scattered thunderstorm activity is expected, but organized severe potential appears low given aforementioned weak deep-layer flow/vertical shear, and a lack of any stronger large-scale ascent. ..Leitman.. 07/19/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 AM CDT Fri Jul 19 2024 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe-thunderstorm potential is expected to be low on Sunday. ...Synopsis... An upper ridge will persist over the western states on Sunday. Further east, broad upper troughing will envelop the central/eastern portions of the U.S. Weak mid/upper flow also is expected, limiting vertical shear. At the surface, high pressure will generally extent east from the Great Lakes to the Northeast. A seasonally moist airmass will extend from the southern Plains through the Mid-South/Southeast and Mid-Atlantic. Scattered thunderstorm activity is expected, but organized severe potential appears low given aforementioned weak deep-layer flow/vertical shear, and a lack of any stronger large-scale ascent. ..Leitman.. 07/19/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0205 AM CDT Fri Jul 19 2024 Valid 201200Z - 211200Z ...Synopsis... An upper ridge over the western Rockies will persist D2/Saturday as a broad Pacific trough moves onshore over the Northwest. To the east, northwesterly flow aloft will continue over the northern Rockies and Intermountain west, with seasonable monsoon moisture. Widely scattered thunderstorms appear likely through the afternoon with a risk for lightning within dry fuels. ...Northwest into the Great Basin and northern Rockies... With the approach of the West Coast trough, weak ascent will allow for isolated thunderstorm development along the higher terrain of the Sierra and Cascades by early afternoon. Initial PWAT values of 0.8 to 1 inches will favor drier storm over areas of significantly dry fuels and recent fire activity. Storm coverage may increase overnight as the upper trough continues onshore and ascent increases. While PWATs should also increase above 1 inch with onshore flow, faster storm motions will tend to limit wetting rainfall, favoring drier storms. While confidence in convective evolution toward the end of the period is lower, some guidance suggests the largest increase in storm coverage after dark may be focused west of the Cascades toward the coastal ranges of OR and northern CA. Farther east into the Great Basin and northern Rockies, confidence in dry storms is somewhat lower. Flow aloft along the eastern periphery of the ridge will be weaker with deeper monsoonal moisture in place. The combination of slower storm speeds and higher PWATs suggests storms may have greater rainfall efficiency. Still, the potential for lighting outside of the wetter cores from scattered storm coverage, and the possibility of a few drier storms, suggest some threat for lightning ignitions within mostly receptive fuels. ..Lyons.. 07/19/2024 ...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 0205 AM CDT Fri Jul 19 2024 Valid 201200Z - 211200Z ...Synopsis... An upper ridge over the western Rockies will persist D2/Saturday as a broad Pacific trough moves onshore over the Northwest. To the east, northwesterly flow aloft will continue over the northern Rockies and Intermountain west, with seasonable monsoon moisture. Widely scattered thunderstorms appear likely through the afternoon with a risk for lightning within dry fuels. ...Northwest into the Great Basin and northern Rockies... With the approach of the West Coast trough, weak ascent will allow for isolated thunderstorm development along the higher terrain of the Sierra and Cascades by early afternoon. Initial PWAT values of 0.8 to 1 inches will favor drier storm over areas of significantly dry fuels and recent fire activity. Storm coverage may increase overnight as the upper trough continues onshore and ascent increases. While PWATs should also increase above 1 inch with onshore flow, faster storm motions will tend to limit wetting rainfall, favoring drier storms. While confidence in convective evolution toward the end of the period is lower, some guidance suggests the largest increase in storm coverage after dark may be focused west of the Cascades toward the coastal ranges of OR and northern CA. Farther east into the Great Basin and northern Rockies, confidence in dry storms is somewhat lower. Flow aloft along the eastern periphery of the ridge will be weaker with deeper monsoonal moisture in place. The combination of slower storm speeds and higher PWATs suggests storms may have greater rainfall efficiency. Still, the potential for lighting outside of the wetter cores from scattered storm coverage, and the possibility of a few drier storms, suggest some threat for lightning ignitions within mostly receptive fuels. ..Lyons.. 07/19/2024 ...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 0205 AM CDT Fri Jul 19 2024 Valid 201200Z - 211200Z ...Synopsis... An upper ridge over the western Rockies will persist D2/Saturday as a broad Pacific trough moves onshore over the Northwest. To the east, northwesterly flow aloft will continue over the northern Rockies and Intermountain west, with seasonable monsoon moisture. Widely scattered thunderstorms appear likely through the afternoon with a risk for lightning within dry fuels. ...Northwest into the Great Basin and northern Rockies... With the approach of the West Coast trough, weak ascent will allow for isolated thunderstorm development along the higher terrain of the Sierra and Cascades by early afternoon. Initial PWAT values of 0.8 to 1 inches will favor drier storm over areas of significantly dry fuels and recent fire activity. Storm coverage may increase overnight as the upper trough continues onshore and ascent increases. While PWATs should also increase above 1 inch with onshore flow, faster storm motions will tend to limit wetting rainfall, favoring drier storms. While confidence in convective evolution toward the end of the period is lower, some guidance suggests the largest increase in storm coverage after dark may be focused west of the Cascades toward the coastal ranges of OR and northern CA. Farther east into the Great Basin and northern Rockies, confidence in dry storms is somewhat lower. Flow aloft along the eastern periphery of the ridge will be weaker with deeper monsoonal moisture in place. The combination of slower storm speeds and higher PWATs suggests storms may have greater rainfall efficiency. Still, the potential for lighting outside of the wetter cores from scattered storm coverage, and the possibility of a few drier storms, suggest some threat for lightning ignitions within mostly receptive fuels. ..Lyons.. 07/19/2024 ...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 0205 AM CDT Fri Jul 19 2024 Valid 201200Z - 211200Z ...Synopsis... An upper ridge over the western Rockies will persist D2/Saturday as a broad Pacific trough moves onshore over the Northwest. To the east, northwesterly flow aloft will continue over the northern Rockies and Intermountain west, with seasonable monsoon moisture. Widely scattered thunderstorms appear likely through the afternoon with a risk for lightning within dry fuels. ...Northwest into the Great Basin and northern Rockies... With the approach of the West Coast trough, weak ascent will allow for isolated thunderstorm development along the higher terrain of the Sierra and Cascades by early afternoon. Initial PWAT values of 0.8 to 1 inches will favor drier storm over areas of significantly dry fuels and recent fire activity. Storm coverage may increase overnight as the upper trough continues onshore and ascent increases. While PWATs should also increase above 1 inch with onshore flow, faster storm motions will tend to limit wetting rainfall, favoring drier storms. While confidence in convective evolution toward the end of the period is lower, some guidance suggests the largest increase in storm coverage after dark may be focused west of the Cascades toward the coastal ranges of OR and northern CA. Farther east into the Great Basin and northern Rockies, confidence in dry storms is somewhat lower. Flow aloft along the eastern periphery of the ridge will be weaker with deeper monsoonal moisture in place. The combination of slower storm speeds and higher PWATs suggests storms may have greater rainfall efficiency. Still, the potential for lighting outside of the wetter cores from scattered storm coverage, and the possibility of a few drier storms, suggest some threat for lightning ignitions within mostly receptive fuels. ..Lyons.. 07/19/2024 ...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 0200 AM CDT Fri Jul 19 2024 Valid 191200Z - 201200Z ...Synopsis... A persistent upper ridge centered over the Great Basin will remain in place through the forecast period, as several weak mid-level perturbations round the periphery of the anticyclone over the northern Rockies and Northwest. Abundant monsoonal moisture and subtle ascent from the passing shortwave troughs will allow for scattered thunderstorm development this afternoon and evening. Isolated dry thunderstorms are possible over parts of the northern Great Basin. ...Northern Great Basin... Along the northern periphery of the ridge, a mid-level shortwave trough will pass over the Pacific Northwest, bringing subtle ascent over the northern Great Basin. PWAT values of 0.8-1 inches will allow sufficient destabilization for scattered thunderstorm coverage through the afternoon and evening. Despite somewhat slow storm speeds and several days of sporadic wetting rainfall, a deep and well-mixed boundary layer will yield poor precipitation efficiency for any thunderstorms. These mostly dry thunderstorms over receptive fuels will pose an increased risk for lightning ignitions across portions of northern NV, western ID and extreme southeast OR. ..Lyons.. 07/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more