Severe Storms

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Sat Aug 24 2024 Valid 271200Z - 011200Z ...DISCUSSION... Within the faster belt of upper flow across the northern U.S., substantial differences in timing of the disturbances in the flow are manifest from the very start of the medium-range period. On Tuesday/Day 4, an energetic short-wave trough should be crossing the north-central U.S., headed toward the Upper Mississippi Valley/southern Ontario, while an upstream trough crosses western Canada and the Pacific Northwest, and a downstream one crosses northern Quebec. However, noted differences in both timing and orientation of these features is immediately apparent. The north-central U.S. feature -- the one associated with Day-4 severe risk over the Great Lakes region -- is roughly 12 hours slower, and evolves to a more negatively tilted configuration in the ECMWF, as compared to the GFS. This results in fairly substantial differences in the surface pattern as well, prohibiting any forecast of the specifics regarding the severe-weather potential on Tuesday. Still, severe-weather risk is apparent despite east-west geographical uncertainties. Thus, will introduce an elongated 15% area across the Upper Midwest and Great Lakes region, given likelihood for existence of a favorably unstable/amply sheared environment in the vicinity of a surface front likely to stretch east-northeastward to west-southwestward across this region. Damaging winds and hail would likely be the primary risks. By Day 5, differences continue to amplify. Risk for severe weather may evolve across portions of the Northeast (favored by the GFS), and/or parts of the Midwest/Ohio Valley (favored by the ECMWF). However, the differences are substantial enough amongst the models to preclude an areal highlight at this time. Meanwhile farther west, an upper low/trough is forecast to be moving across the northwestern U.S. and Canadian Prairie early in the day, but location/timing, and intensity differences with this feature are pronounced. While some severe risk may evolve across parts of the north-central U.S. ahead of this feature and an associated cold front, the differences preclude any areal outlines at this time. Predictability issues persist through the remainder of the period, with model solutions diverging steadily through the upcoming Labor Day weekend. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Sat Aug 24 2024 Valid 271200Z - 011200Z ...DISCUSSION... Within the faster belt of upper flow across the northern U.S., substantial differences in timing of the disturbances in the flow are manifest from the very start of the medium-range period. On Tuesday/Day 4, an energetic short-wave trough should be crossing the north-central U.S., headed toward the Upper Mississippi Valley/southern Ontario, while an upstream trough crosses western Canada and the Pacific Northwest, and a downstream one crosses northern Quebec. However, noted differences in both timing and orientation of these features is immediately apparent. The north-central U.S. feature -- the one associated with Day-4 severe risk over the Great Lakes region -- is roughly 12 hours slower, and evolves to a more negatively tilted configuration in the ECMWF, as compared to the GFS. This results in fairly substantial differences in the surface pattern as well, prohibiting any forecast of the specifics regarding the severe-weather potential on Tuesday. Still, severe-weather risk is apparent despite east-west geographical uncertainties. Thus, will introduce an elongated 15% area across the Upper Midwest and Great Lakes region, given likelihood for existence of a favorably unstable/amply sheared environment in the vicinity of a surface front likely to stretch east-northeastward to west-southwestward across this region. Damaging winds and hail would likely be the primary risks. By Day 5, differences continue to amplify. Risk for severe weather may evolve across portions of the Northeast (favored by the GFS), and/or parts of the Midwest/Ohio Valley (favored by the ECMWF). However, the differences are substantial enough amongst the models to preclude an areal highlight at this time. Meanwhile farther west, an upper low/trough is forecast to be moving across the northwestern U.S. and Canadian Prairie early in the day, but location/timing, and intensity differences with this feature are pronounced. While some severe risk may evolve across parts of the north-central U.S. ahead of this feature and an associated cold front, the differences preclude any areal outlines at this time. Predictability issues persist through the remainder of the period, with model solutions diverging steadily through the upcoming Labor Day weekend. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Sat Aug 24 2024 Valid 271200Z - 011200Z ...DISCUSSION... Within the faster belt of upper flow across the northern U.S., substantial differences in timing of the disturbances in the flow are manifest from the very start of the medium-range period. On Tuesday/Day 4, an energetic short-wave trough should be crossing the north-central U.S., headed toward the Upper Mississippi Valley/southern Ontario, while an upstream trough crosses western Canada and the Pacific Northwest, and a downstream one crosses northern Quebec. However, noted differences in both timing and orientation of these features is immediately apparent. The north-central U.S. feature -- the one associated with Day-4 severe risk over the Great Lakes region -- is roughly 12 hours slower, and evolves to a more negatively tilted configuration in the ECMWF, as compared to the GFS. This results in fairly substantial differences in the surface pattern as well, prohibiting any forecast of the specifics regarding the severe-weather potential on Tuesday. Still, severe-weather risk is apparent despite east-west geographical uncertainties. Thus, will introduce an elongated 15% area across the Upper Midwest and Great Lakes region, given likelihood for existence of a favorably unstable/amply sheared environment in the vicinity of a surface front likely to stretch east-northeastward to west-southwestward across this region. Damaging winds and hail would likely be the primary risks. By Day 5, differences continue to amplify. Risk for severe weather may evolve across portions of the Northeast (favored by the GFS), and/or parts of the Midwest/Ohio Valley (favored by the ECMWF). However, the differences are substantial enough amongst the models to preclude an areal highlight at this time. Meanwhile farther west, an upper low/trough is forecast to be moving across the northwestern U.S. and Canadian Prairie early in the day, but location/timing, and intensity differences with this feature are pronounced. While some severe risk may evolve across parts of the north-central U.S. ahead of this feature and an associated cold front, the differences preclude any areal outlines at this time. Predictability issues persist through the remainder of the period, with model solutions diverging steadily through the upcoming Labor Day weekend. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0241 AM CDT Sat Aug 24 2024 Valid 261200Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF SOUTH DAKOTA EASTWARD TO THE WISCONSIN VICINITY... ...SUMMARY... Severe storms are expected to evolve within a zone extending from the northern High Plains eastward to the Wisconsin vicinity, and southward to the southern High Plains during the afternoon and evening Monday. A few severe storms are also expected across the Northeast and Mid-Atlantic region. ...Synopsis... An upper trough over the Intermountain West at the start of the period is forecast to eject northeastward across the High Plains into the north-central U.S. by the second half of the period. This will result in weakening of the persistent upper ridge over the central CONUS. Meanwhile, a weak upper low is forecast to shift south-southeastward across the Northeast/New England through the period. At the surface, a baroclinic zone lying across the north-central U.S. will sharpen and shift southeastward through the second half of the period, as the upper system shifts into/across the northern Plains. This front will likely focus severe storm development during the afternoon and evening hours. ...South Dakota vicinity to the Upper Great Lakes... While timing of the ejection of the upper system into/across the north-central U.S. remains a bit uncertain due to differences in the output from various models, a general consensus that afternoon storm initiation will occur across this region exists, as a very unstable airmass evolves diurnally. With flow forecast to veer/increase with height to southwesterly at 40 to 50 kt, shear will support organized/supercell storms. Coverage through the daylight hours may remain isolated across much of the region however, due to low-level capping. Still, any storms which do develop would be capable of producing large hail and damaging winds. Storm coverage may increase overnight as the trough advances and a southwesterly low-level jet develops, with convection -- and ongoing severe risk, spreading eastward across the Upper Midwest into the Upper Mississippi Valley into early Tuesday morning ...The High Plains... Modest afternoon destabilization forecast across the High Plains from southeastern Montana southward to northeastern New Mexico and the Texas/Oklahoma Panhandles should support isolated storm development. This development will be aided by increasing large-scale ascent associated with the ejection of the upper trough across the High Plains region during the afternoon. While flow aloft will be stronger with northward extent, supporting a few strong/severe storms with damaging wind potential, the very deep afternoon mixed layer farther south (mixed to/above 700 mb) will likely compensate somewhat for the lack of shear. As such, isolated severe gust potential may extend southward into the southern High Plains. ...The Northeast and Mid-Atlantic region... As a weak upper low shifts southeastward across the Northeast, modest afternoon destabilization is expected across portions of the region. While uncertainty regarding ample CAPE development exists, a belt of enhanced northwesterly flow aloft on the southern and western flank of the low will provide sufficient shear for southeastward-moving storms and potentially linear segments/clusters. Presuming at least minimally sufficient afternoon destabilization, stronger storms would pose a risk for damaging gusts locally, into the early evening hours. ..Goss.. 08/24/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0241 AM CDT Sat Aug 24 2024 Valid 261200Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF SOUTH DAKOTA EASTWARD TO THE WISCONSIN VICINITY... ...SUMMARY... Severe storms are expected to evolve within a zone extending from the northern High Plains eastward to the Wisconsin vicinity, and southward to the southern High Plains during the afternoon and evening Monday. A few severe storms are also expected across the Northeast and Mid-Atlantic region. ...Synopsis... An upper trough over the Intermountain West at the start of the period is forecast to eject northeastward across the High Plains into the north-central U.S. by the second half of the period. This will result in weakening of the persistent upper ridge over the central CONUS. Meanwhile, a weak upper low is forecast to shift south-southeastward across the Northeast/New England through the period. At the surface, a baroclinic zone lying across the north-central U.S. will sharpen and shift southeastward through the second half of the period, as the upper system shifts into/across the northern Plains. This front will likely focus severe storm development during the afternoon and evening hours. ...South Dakota vicinity to the Upper Great Lakes... While timing of the ejection of the upper system into/across the north-central U.S. remains a bit uncertain due to differences in the output from various models, a general consensus that afternoon storm initiation will occur across this region exists, as a very unstable airmass evolves diurnally. With flow forecast to veer/increase with height to southwesterly at 40 to 50 kt, shear will support organized/supercell storms. Coverage through the daylight hours may remain isolated across much of the region however, due to low-level capping. Still, any storms which do develop would be capable of producing large hail and damaging winds. Storm coverage may increase overnight as the trough advances and a southwesterly low-level jet develops, with convection -- and ongoing severe risk, spreading eastward across the Upper Midwest into the Upper Mississippi Valley into early Tuesday morning ...The High Plains... Modest afternoon destabilization forecast across the High Plains from southeastern Montana southward to northeastern New Mexico and the Texas/Oklahoma Panhandles should support isolated storm development. This development will be aided by increasing large-scale ascent associated with the ejection of the upper trough across the High Plains region during the afternoon. While flow aloft will be stronger with northward extent, supporting a few strong/severe storms with damaging wind potential, the very deep afternoon mixed layer farther south (mixed to/above 700 mb) will likely compensate somewhat for the lack of shear. As such, isolated severe gust potential may extend southward into the southern High Plains. ...The Northeast and Mid-Atlantic region... As a weak upper low shifts southeastward across the Northeast, modest afternoon destabilization is expected across portions of the region. While uncertainty regarding ample CAPE development exists, a belt of enhanced northwesterly flow aloft on the southern and western flank of the low will provide sufficient shear for southeastward-moving storms and potentially linear segments/clusters. Presuming at least minimally sufficient afternoon destabilization, stronger storms would pose a risk for damaging gusts locally, into the early evening hours. ..Goss.. 08/24/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0241 AM CDT Sat Aug 24 2024 Valid 261200Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF SOUTH DAKOTA EASTWARD TO THE WISCONSIN VICINITY... ...SUMMARY... Severe storms are expected to evolve within a zone extending from the northern High Plains eastward to the Wisconsin vicinity, and southward to the southern High Plains during the afternoon and evening Monday. A few severe storms are also expected across the Northeast and Mid-Atlantic region. ...Synopsis... An upper trough over the Intermountain West at the start of the period is forecast to eject northeastward across the High Plains into the north-central U.S. by the second half of the period. This will result in weakening of the persistent upper ridge over the central CONUS. Meanwhile, a weak upper low is forecast to shift south-southeastward across the Northeast/New England through the period. At the surface, a baroclinic zone lying across the north-central U.S. will sharpen and shift southeastward through the second half of the period, as the upper system shifts into/across the northern Plains. This front will likely focus severe storm development during the afternoon and evening hours. ...South Dakota vicinity to the Upper Great Lakes... While timing of the ejection of the upper system into/across the north-central U.S. remains a bit uncertain due to differences in the output from various models, a general consensus that afternoon storm initiation will occur across this region exists, as a very unstable airmass evolves diurnally. With flow forecast to veer/increase with height to southwesterly at 40 to 50 kt, shear will support organized/supercell storms. Coverage through the daylight hours may remain isolated across much of the region however, due to low-level capping. Still, any storms which do develop would be capable of producing large hail and damaging winds. Storm coverage may increase overnight as the trough advances and a southwesterly low-level jet develops, with convection -- and ongoing severe risk, spreading eastward across the Upper Midwest into the Upper Mississippi Valley into early Tuesday morning ...The High Plains... Modest afternoon destabilization forecast across the High Plains from southeastern Montana southward to northeastern New Mexico and the Texas/Oklahoma Panhandles should support isolated storm development. This development will be aided by increasing large-scale ascent associated with the ejection of the upper trough across the High Plains region during the afternoon. While flow aloft will be stronger with northward extent, supporting a few strong/severe storms with damaging wind potential, the very deep afternoon mixed layer farther south (mixed to/above 700 mb) will likely compensate somewhat for the lack of shear. As such, isolated severe gust potential may extend southward into the southern High Plains. ...The Northeast and Mid-Atlantic region... As a weak upper low shifts southeastward across the Northeast, modest afternoon destabilization is expected across portions of the region. While uncertainty regarding ample CAPE development exists, a belt of enhanced northwesterly flow aloft on the southern and western flank of the low will provide sufficient shear for southeastward-moving storms and potentially linear segments/clusters. Presuming at least minimally sufficient afternoon destabilization, stronger storms would pose a risk for damaging gusts locally, into the early evening hours. ..Goss.. 08/24/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0241 AM CDT Sat Aug 24 2024 Valid 261200Z - 271200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF SOUTH DAKOTA EASTWARD TO THE WISCONSIN VICINITY... ...SUMMARY... Severe storms are expected to evolve within a zone extending from the northern High Plains eastward to the Wisconsin vicinity, and southward to the southern High Plains during the afternoon and evening Monday. A few severe storms are also expected across the Northeast and Mid-Atlantic region. ...Synopsis... An upper trough over the Intermountain West at the start of the period is forecast to eject northeastward across the High Plains into the north-central U.S. by the second half of the period. This will result in weakening of the persistent upper ridge over the central CONUS. Meanwhile, a weak upper low is forecast to shift south-southeastward across the Northeast/New England through the period. At the surface, a baroclinic zone lying across the north-central U.S. will sharpen and shift southeastward through the second half of the period, as the upper system shifts into/across the northern Plains. This front will likely focus severe storm development during the afternoon and evening hours. ...South Dakota vicinity to the Upper Great Lakes... While timing of the ejection of the upper system into/across the north-central U.S. remains a bit uncertain due to differences in the output from various models, a general consensus that afternoon storm initiation will occur across this region exists, as a very unstable airmass evolves diurnally. With flow forecast to veer/increase with height to southwesterly at 40 to 50 kt, shear will support organized/supercell storms. Coverage through the daylight hours may remain isolated across much of the region however, due to low-level capping. Still, any storms which do develop would be capable of producing large hail and damaging winds. Storm coverage may increase overnight as the trough advances and a southwesterly low-level jet develops, with convection -- and ongoing severe risk, spreading eastward across the Upper Midwest into the Upper Mississippi Valley into early Tuesday morning ...The High Plains... Modest afternoon destabilization forecast across the High Plains from southeastern Montana southward to northeastern New Mexico and the Texas/Oklahoma Panhandles should support isolated storm development. This development will be aided by increasing large-scale ascent associated with the ejection of the upper trough across the High Plains region during the afternoon. While flow aloft will be stronger with northward extent, supporting a few strong/severe storms with damaging wind potential, the very deep afternoon mixed layer farther south (mixed to/above 700 mb) will likely compensate somewhat for the lack of shear. As such, isolated severe gust potential may extend southward into the southern High Plains. ...The Northeast and Mid-Atlantic region... As a weak upper low shifts southeastward across the Northeast, modest afternoon destabilization is expected across portions of the region. While uncertainty regarding ample CAPE development exists, a belt of enhanced northwesterly flow aloft on the southern and western flank of the low will provide sufficient shear for southeastward-moving storms and potentially linear segments/clusters. Presuming at least minimally sufficient afternoon destabilization, stronger storms would pose a risk for damaging gusts locally, into the early evening hours. ..Goss.. 08/24/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0130 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...Synopsis... A mid-level trough positioned over the West will lift northeast into the Northern Rockies while undergoing gradual weakening. Still, enough residual enhanced mid-level flow will overspread adjacent regions of the Northern Rockies, to result in afternoon sustained surface winds of 15-20 mph and RH values into the low 20s F. These dry/breezy conditions will promote Elevated fire-weather conditions across portions of Wyoming where fuels remain at least marginally receptive to large-fire spread. In addition, an area delineating the potential for isolated dry thunderstorms has been added for portions of the northern Great Basin into the Northern Rockies. Isolated storms should develop during the afternoon in association with forcing/ascent with the mid-level trough. This highlight has been confined to areas where fuels appear receptive to large-fire spread. ..Karstens.. 08/24/2024 ...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 0130 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...Synopsis... A mid-level trough positioned over the West will lift northeast into the Northern Rockies while undergoing gradual weakening. Still, enough residual enhanced mid-level flow will overspread adjacent regions of the Northern Rockies, to result in afternoon sustained surface winds of 15-20 mph and RH values into the low 20s F. These dry/breezy conditions will promote Elevated fire-weather conditions across portions of Wyoming where fuels remain at least marginally receptive to large-fire spread. In addition, an area delineating the potential for isolated dry thunderstorms has been added for portions of the northern Great Basin into the Northern Rockies. Isolated storms should develop during the afternoon in association with forcing/ascent with the mid-level trough. This highlight has been confined to areas where fuels appear receptive to large-fire spread. ..Karstens.. 08/24/2024 ...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 0130 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...Synopsis... A mid-level trough positioned over the West will lift northeast into the Northern Rockies while undergoing gradual weakening. Still, enough residual enhanced mid-level flow will overspread adjacent regions of the Northern Rockies, to result in afternoon sustained surface winds of 15-20 mph and RH values into the low 20s F. These dry/breezy conditions will promote Elevated fire-weather conditions across portions of Wyoming where fuels remain at least marginally receptive to large-fire spread. In addition, an area delineating the potential for isolated dry thunderstorms has been added for portions of the northern Great Basin into the Northern Rockies. Isolated storms should develop during the afternoon in association with forcing/ascent with the mid-level trough. This highlight has been confined to areas where fuels appear receptive to large-fire spread. ..Karstens.. 08/24/2024 ...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 0130 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...Synopsis... A mid-level trough positioned over the West will lift northeast into the Northern Rockies while undergoing gradual weakening. Still, enough residual enhanced mid-level flow will overspread adjacent regions of the Northern Rockies, to result in afternoon sustained surface winds of 15-20 mph and RH values into the low 20s F. These dry/breezy conditions will promote Elevated fire-weather conditions across portions of Wyoming where fuels remain at least marginally receptive to large-fire spread. In addition, an area delineating the potential for isolated dry thunderstorms has been added for portions of the northern Great Basin into the Northern Rockies. Isolated storms should develop during the afternoon in association with forcing/ascent with the mid-level trough. This highlight has been confined to areas where fuels appear receptive to large-fire spread. ..Karstens.. 08/24/2024 ...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 0129 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL WYOMING... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN UTAH INTO SOUTHEAST NEVADA... ...Synopsis... A highly amplified mid-level trough will progress through portions of the interior West throughout the day. A mid-level jet streak will accompany this trough along its southern/eastern periphery. Daytime heating/mixing will allow these winds to mix toward the surface. This process will result in southwesterly sustained surface winds of 25-35 mph and RH values into the teens/single digits F across portions of western Utah into southeast Nevada, amid marginally receptive fuels, supporting Critical fire-weather conditions. Similar wind/RH conditions supporting Critical fire-weather conditions will occur across portions of northern/central Wyoming, albeit with sustained winds of 20-25 mph and RH values into the teens and low 20s F, amid receptive fuels. Farther west, upper forcing for ascent associated with the mid-level trough will foster isolated dry thunderstorms over portions of northern Nevada and vicinity. Fuels in this region remain receptive to large-fire spread with PWAT values ranging from 0.5-0.75 inches. ..Karstens.. 08/24/2024 ...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 0129 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL WYOMING... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN UTAH INTO SOUTHEAST NEVADA... ...Synopsis... A highly amplified mid-level trough will progress through portions of the interior West throughout the day. A mid-level jet streak will accompany this trough along its southern/eastern periphery. Daytime heating/mixing will allow these winds to mix toward the surface. This process will result in southwesterly sustained surface winds of 25-35 mph and RH values into the teens/single digits F across portions of western Utah into southeast Nevada, amid marginally receptive fuels, supporting Critical fire-weather conditions. Similar wind/RH conditions supporting Critical fire-weather conditions will occur across portions of northern/central Wyoming, albeit with sustained winds of 20-25 mph and RH values into the teens and low 20s F, amid receptive fuels. Farther west, upper forcing for ascent associated with the mid-level trough will foster isolated dry thunderstorms over portions of northern Nevada and vicinity. Fuels in this region remain receptive to large-fire spread with PWAT values ranging from 0.5-0.75 inches. ..Karstens.. 08/24/2024 ...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 0129 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL WYOMING... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN UTAH INTO SOUTHEAST NEVADA... ...Synopsis... A highly amplified mid-level trough will progress through portions of the interior West throughout the day. A mid-level jet streak will accompany this trough along its southern/eastern periphery. Daytime heating/mixing will allow these winds to mix toward the surface. This process will result in southwesterly sustained surface winds of 25-35 mph and RH values into the teens/single digits F across portions of western Utah into southeast Nevada, amid marginally receptive fuels, supporting Critical fire-weather conditions. Similar wind/RH conditions supporting Critical fire-weather conditions will occur across portions of northern/central Wyoming, albeit with sustained winds of 20-25 mph and RH values into the teens and low 20s F, amid receptive fuels. Farther west, upper forcing for ascent associated with the mid-level trough will foster isolated dry thunderstorms over portions of northern Nevada and vicinity. Fuels in this region remain receptive to large-fire spread with PWAT values ranging from 0.5-0.75 inches. ..Karstens.. 08/24/2024 ...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 0129 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF NORTHERN/CENTRAL WYOMING... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN UTAH INTO SOUTHEAST NEVADA... ...Synopsis... A highly amplified mid-level trough will progress through portions of the interior West throughout the day. A mid-level jet streak will accompany this trough along its southern/eastern periphery. Daytime heating/mixing will allow these winds to mix toward the surface. This process will result in southwesterly sustained surface winds of 25-35 mph and RH values into the teens/single digits F across portions of western Utah into southeast Nevada, amid marginally receptive fuels, supporting Critical fire-weather conditions. Similar wind/RH conditions supporting Critical fire-weather conditions will occur across portions of northern/central Wyoming, albeit with sustained winds of 20-25 mph and RH values into the teens and low 20s F, amid receptive fuels. Farther west, upper forcing for ascent associated with the mid-level trough will foster isolated dry thunderstorms over portions of northern Nevada and vicinity. Fuels in this region remain receptive to large-fire spread with PWAT values ranging from 0.5-0.75 inches. ..Karstens.. 08/24/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0127 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... CORRECTED FOR THUNDER LINES ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0127 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... CORRECTED FOR THUNDER LINES ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0127 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... CORRECTED FOR THUNDER LINES ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0127 AM CDT Sat Aug 24 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...PARTS OF WESTERN MO...AND PARTS OF THE SOUTHERN PLAINS... CORRECTED FOR THUNDER LINES ...SUMMARY... Strong to locally severe storms are possible today from the Four Corners region northeastward into the central High Plains. Strong to severe storms are also possible across western Missouri and also across western Oklahoma. ...Synopsis... A deep mid/upper-level trough will remain in place over the West today. An embedded mid/upper cyclone is forecast to move southeastward from northern CA into the Great Basin. Downstream, an upper-level anticyclone will remain anchored over the southern Great Plains. One surface low is forecast to gradually deepen across the northern High Plains, while another weak surface low may develop across the south-central High Plains. ...Four Corners region into the central High Plains... The eastern fringe of stronger southwesterly flow aloft (associated with the deep upper trough) will overspread a plume of midlevel moisture from the Four Corners region into the central Rockies. Scattered thunderstorm development is expected across the region this afternoon. Effective shear of 30-40 kt and modest but sufficient buoyancy will support potential for a few loosely organized cells and/or clusters, with a threat of isolated strong to severe gusts. Richer low-level moisture and stronger instability will develop this afternoon across parts of the central High Plains, where moist easterly flow is maintained to the north of a nearly stationary surface boundary. With capping and weaker large-scale ascent expected, storm initiation within this more-unstable regime may be suppressed. However, high-based convection that develops over the higher terrain could spread into the central High Plains by early evening, potentially accompanied by an isolated strong to severe gusts and perhaps some hail. ...Western MO and vicinity... Most guidance suggests an increase in elevated convection near and after 12Z across parts of western MO, driven by low-level warm advection and moistening in the 850-700 mb layer. Effective shear will not be particularly strong, but relatively steep midlevel lapse rates and moderate elevated buoyancy will support potential for a few robust storms. Isolated hail cannot be ruled out with the strongest storms. Also, despite the elevated nature of the convection, initially rather dry profiles below the moist layer could support locally strong gusts. Depending on the coverage and intensity of morning convection, cold-pool development will be possible, which could lead to a southward-propagating cluster across western MO. This scenario remains quite uncertain, but there will be some potential for an isolated damaging-gust threat to spread into southwest MO from late morning into the afternoon. ...Parts of western OK into northwest TX... Despite generally weak large-scale ascent, some guidance suggests potential for isolated to widely scattered thunderstorm development within a very hot/well-mixed environment across parts of western OK into northwest TX late this afternoon into the early evening. With weak deep-layer shear and the influence of the upper ridge, storms will likely remain disorganized, and coverage of storms remains uncertain. However, any stronger storm within this environment would pose a conditional microburst threat. A 5% wind area has been added where relative confidence in storm development is currently greatest. ...Northeast MT into northwest ND... Moderate to locally strong instability may develop this afternoon from far northeast MT into northwest ND, with sufficient deep-layer shear to support storm organization. However, large-scale ascent is expected to remain rather weak across the region, and there is only a very weak signal for diurnal storm development. Some threat for severe hail and/or wind could accompany any robust storm within this regime, but confidence in storm coverage is too low for probabilities at this time. ..Dean/Karstens.. 08/24/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0110 AM CDT Sat Aug 24 2024 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN DAKOTAS INTO NORTHWESTERN MINNESOTA... ...SUMMARY... Scattered severe storms may develop across the northern Plains area on Sunday, with more isolated severe potential southwestward into the southern Rockies on Sunday. A couple of strong/marginally severe storms may also occur across the Lower Great Lakes/Upper Ohio Valley vicinity. ...Synopsis... A progressing western U.S. upper trough is forecast to gradually weaken, as it impinges on a persistent central U.S. ridge. The result will be that the trough gets shunted northeastward toward Montana/Wyoming with time. Meanwhile, weak upper troughing will persist over the Northeast. At the surface, a cold front will progress eastward across the Canadian Prairie, and the north-central U.S. with time. By the end of the period, the front should stretch from Minnesota southwestward to northeastern Colorado. ...Northern Plains southwestward to the Four Corners region... As the western U.S. trough advances eastward, large-scale ascent will support scattered thunderstorm development across the Intermountain Region, within a diurnally destabilizing airmass. While CAPE will remain limited, moderate southwesterly flow aloft ahead of the trough will allow some storm organization/longevity at time. This, combined with a deep mixed layer providing support for enhanced downdrafts with the stronger cells, will result in risk for locally severe wind gusts. More substantial severe risk could evolve across portions of the north-central states, where much greater instability will evolve. Though the airmass should remain capped in most areas, ascent may be sufficient to support local cap breaches by late afternoon to allow isolated storm development. If storms develop, upscale growth near convective outflows would be expected, possibly resulting in evening/overnight MCS development. Large hail would be possible with the initial storms, though with locally damaging gusts likely to be the dominant risk. Still, given the capping that is anticipated, and questions whether ascent will be sufficient to allow storm development, will maintain only conditional 15%/SLGT risk at this time. ...Lower Great Lakes/Upper Ohio Valley area... On the western fringe of the northeastern U.S. trough, moderate northwesterly flow aloft may combine with modest afternoon destabilization to support isolated storm development. Assuming this occurs, a few strong gusts would be possible as storms would move rather quickly southeastward. The main question remains the degree of destabilization which may occur, and thus will introduce only 5%/MRGL risk at this time. ..Goss.. 08/24/2024 Read more