SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

WW 0639 Status Updates
STATUS FOR WATCH 0639 HAS NOT BEEN ISSUED YET Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Mon Aug 19 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE MONTANA/NORTH DAKOTA BORDER VICINITY... ...SUMMARY... Widely scattered to potentially scattered storms will be possible on Wednesday across parts of the northern High Plains. Severe winds and large hail could occur. Marginally severe storms will be possible westward into central Montana and southward into the central High Plains. ...Synopsis... Broad cyclonic flow will continue across portions of the Western U.S. A mid-level shortwave trough is expected to lift northeastward through the northern Rockies into the northern High Plains late Wednesday afternoon into the evening. A surface low will deepen near the Montana/North Dakota border with a lee trough extending into the central High Plains. ...Montana into North Dakota... Convection is likely to form within the higher terrain of southwest Montana. Deep-layer shear will be strong, but buoyancy will be weak to modest. Strong/severe wind gusts and isolated large hail are possible. Greater uncertainty exists in the exact scenario for the Montana/North Dakota border vicinity. With the surface low deepening, a few storms could initiate during the mid/late-afternoon. These storms would have a greater chance at maintaining a supercellular mode. Severe wind gusts and large hail would be the main hazards with this scenario. However, mid-level heights will be mostly neutral through the day before modest falls occur by early evening and low-level forcing will be limited as well. A second possibility is for activity in Montana to move into the border region during early/mid-evening. Severe winds would be the primary hazard with what would likely be outflow-dominant storms. Given the late timing of these storms, it is not certain how much severe coverage there would be. The 15% severe probability area will be maintained this cycle with guidance hopefully providing more clarity in the coming days. ...Black Hills into central High Plains... Isolated to widely scattered storms are possible within the lee trough. Shear will be weaker with southern extent. A few severe gusts and marginally severe hail could occur with the strongest storms during the afternoon. ...Mid-Missouri Valley... Some convection may be ongoing in eastern South Dakota into southern Minnesota early in the period. Some outflow can be expected with this activity. With the MCV, flow aloft will be enhanced into eastern Nebraska. While a conditional threat for a strong/severe storm exists, low/mid-level forcing will be weak and storm initiation is far from certain. ..Wendt.. 08/19/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Mon Aug 19 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE MONTANA/NORTH DAKOTA BORDER VICINITY... ...SUMMARY... Widely scattered to potentially scattered storms will be possible on Wednesday across parts of the northern High Plains. Severe winds and large hail could occur. Marginally severe storms will be possible westward into central Montana and southward into the central High Plains. ...Synopsis... Broad cyclonic flow will continue across portions of the Western U.S. A mid-level shortwave trough is expected to lift northeastward through the northern Rockies into the northern High Plains late Wednesday afternoon into the evening. A surface low will deepen near the Montana/North Dakota border with a lee trough extending into the central High Plains. ...Montana into North Dakota... Convection is likely to form within the higher terrain of southwest Montana. Deep-layer shear will be strong, but buoyancy will be weak to modest. Strong/severe wind gusts and isolated large hail are possible. Greater uncertainty exists in the exact scenario for the Montana/North Dakota border vicinity. With the surface low deepening, a few storms could initiate during the mid/late-afternoon. These storms would have a greater chance at maintaining a supercellular mode. Severe wind gusts and large hail would be the main hazards with this scenario. However, mid-level heights will be mostly neutral through the day before modest falls occur by early evening and low-level forcing will be limited as well. A second possibility is for activity in Montana to move into the border region during early/mid-evening. Severe winds would be the primary hazard with what would likely be outflow-dominant storms. Given the late timing of these storms, it is not certain how much severe coverage there would be. The 15% severe probability area will be maintained this cycle with guidance hopefully providing more clarity in the coming days. ...Black Hills into central High Plains... Isolated to widely scattered storms are possible within the lee trough. Shear will be weaker with southern extent. A few severe gusts and marginally severe hail could occur with the strongest storms during the afternoon. ...Mid-Missouri Valley... Some convection may be ongoing in eastern South Dakota into southern Minnesota early in the period. Some outflow can be expected with this activity. With the MCV, flow aloft will be enhanced into eastern Nebraska. While a conditional threat for a strong/severe storm exists, low/mid-level forcing will be weak and storm initiation is far from certain. ..Wendt.. 08/19/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0208 PM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...20z Update... Confidence has increased that a corridor of elevated to locally critical fire-weather conditions are possible over parts of eastern ID into southwestern MT D2/Tuesday. Stronger flow aloft ahead of a weak upper trough embedded within southwesterly flow will support deeper mixing and wind gusts to 15-20 mph as it passes overhead through the afternoon. With RH below 20% and dry area fuels, fire-weather concerns are expected to be elevated. Otherwise, the previous forecast remains valid with minimal changes. ..Lyons.. 08/19/2024 .PREV DISCUSSION... /ISSUED 0158 AM CDT Mon Aug 19 2024/ ...Synopsis... The West Coast mid-level trough will slowly progress eastward tomorrow (Tuesday), with strong southwesterly 500 mb flow expected to overspread the Great Basin. Similar to Day 1 (today), afternoon boundary-layer mixing will promote dry and windy conditions along the Oregon/California/Nevada border, as well as southwestern into central Nevada, where Elevated highlights have been added. ...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 0208 PM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...20z Update... Confidence has increased that a corridor of elevated to locally critical fire-weather conditions are possible over parts of eastern ID into southwestern MT D2/Tuesday. Stronger flow aloft ahead of a weak upper trough embedded within southwesterly flow will support deeper mixing and wind gusts to 15-20 mph as it passes overhead through the afternoon. With RH below 20% and dry area fuels, fire-weather concerns are expected to be elevated. Otherwise, the previous forecast remains valid with minimal changes. ..Lyons.. 08/19/2024 .PREV DISCUSSION... /ISSUED 0158 AM CDT Mon Aug 19 2024/ ...Synopsis... The West Coast mid-level trough will slowly progress eastward tomorrow (Tuesday), with strong southwesterly 500 mb flow expected to overspread the Great Basin. Similar to Day 1 (today), afternoon boundary-layer mixing will promote dry and windy conditions along the Oregon/California/Nevada border, as well as southwestern into central Nevada, where Elevated highlights have been added. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1209 PM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR MUCH OF MONTANA INTO PARTS OF THE NORTHERN/CENTRAL HIGH PLAINS... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains on Tuesday. Severe winds and large hail are the primary threats. ...Synopsis... An upper-level trough will remain in the Northwest and make slow progress eastward. A modest surface trough will develop in the northern and central High Plains. The upper-level ridge will amplify slightly in the central U.S. Surface high pressure will be centered in the Great Lakes with offshore flow expected across much of the eastern U.S. Some moisture return is possible along the western flank of the surface high in the High Plains region. ...Montana... Widely scattered to scattered thunderstorms are expected to develop within the terrain of southwestern and south-central Montana during the afternoon. This activity is expected to progress to the northeast into the evening. Initial storms will likely be discrete, but rather large temperature-dewpoint spreads should promote outflow dominant storms that will tend to grow upscale quickly. Severe winds are expected to be the primary hazard, but steep mid-level lapse rates and 40-50 kts of effective shear would support some risk of large hail with the strongest discrete storms. Buoyancy will be minimal within the higher terrain and perhaps reach 1000-1500 J/kg in central Montana. Greater buoyancy will exist into eastern Montana, but MLCIN will also be greater. While a narrow area of greater severe wind potential could develop, the spatial extent appears to low/uncertain for an increase in severe probabilities. ...Black Hills into western Nebraska... Though uncertainty in initiation is high due to weak forcing, an isolated storm or two could develop within the surface trough during the afternoon. Northwesterly flow aloft will be sufficient for 35-40 kts of effective shear. 1500-2500 J/kg MLCAPE is possible by the afternoon. Isolated wind damage and large hail could occur should a storm develop and mature. ..Wendt.. 08/19/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1149 AM CDT Mon Aug 19 2024 Valid 191700Z - 201200Z ...17z Update... No changes were made to the current outlook. Dry and breezy conditions may support elevated fire-weather potential from the eastern Sierra and across parts of the Great Basin. Scattered thunderstorms may also support some risk for lightning over parts of ID and the northern Rockies. However, confidence in the coverage of dry storms and overlap with receptive fuels is too low for IsoDryT probabilities. ..Lyons.. 08/19/2024 .PREV DISCUSSION... /ISSUED 0157 AM CDT Mon Aug 19 2024/ ...Synopsis... Strong southwesterly mid-level flow will overspread the Interior West as a mid-level trough meanders over the West Coast and an upper ridge persists over the central U.S. today. Boundary-layer mixing to the lee of the Sierra will promote windy conditions amid 10-20 percent RH by afternoon. Elevated highlights have been maintained across portions of the Harney Basin in southeast Oregon and adjacent areas, as well as southwest into central Nevada, where the aforementioned dry and windy conditions should persist for several hours atop fuels receptive to wildfire spread. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CDT Mon Aug 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA.... ...SUMMARY... Scattered severe thunderstorms are possible later today across portions of the northern and central High Plains, and over western Montana. Large hail and severe gusts are the primary hazards. ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. ..Hart/Thornton.. 08/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CDT Mon Aug 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA.... ...SUMMARY... Scattered severe thunderstorms are possible later today across portions of the northern and central High Plains, and over western Montana. Large hail and severe gusts are the primary hazards. ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. ..Hart/Thornton.. 08/19/2024 Read more

No watches are valid as of Mon Aug 19 16:22:01 UTC 2024.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon Aug 19 2024 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF WESTERN INTO NORTH-CENTRAL MONTANA...EASTERN MONTANA...AND EASTERN COLORADO... ...SUMMARY... Scattered severe thunderstorms are possible across portions of Montana and eastern Colorado during the afternoon and evening. Large hail and severe gusts are the primary hazards. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level ridge situated over the south-central High Plains northward through the northern Great Plains. A mid-level trough is over the East and a mid-level low and associated trough are over the eastern Pacific to the west of the Pacific Northwest. ...Portions of the central and northern Rockies/High Plains... Broad 40+ kt southwesterly 500 mb flow will overspread portions of the central into the northern Rockies as an impulse embedded in the West Coast mid-level trough grazes the region. Isolated to scattered thunderstorms are forecast across Montana with locally greater thunderstorm coverage forecast over western into north-central MT this afternoon and evening, and separately over portions of eastern Montana. Richer moisture is evident in morning surface analysis across eastern MT where lower 60s F surface dewpoints are present with mid 50s farther west near the I-15 corridor. Consequently, greater buoyancy is expected later this afternoon over eastern MT with 2000+ J/kg MLCAPE possible with 750-1250 J/kg farther west. Given the deep boundary layer and corresponding steep lapse rates in both areas, severe gusts are possible with the more intense cells and clusters, especially if a linear cluster can evolve near the Rocky Mtn Front and push northeastward into the High Plains. Elsewhere, isolated instances of hail/wind may accompany the stronger thunderstorms from the eastern Great Basin northward into ID/WY. ...Eastern Colorado... Moist upslope flow during peak surface heating will result in thunderstorm initiation off of the higher terrain. Surface dewpoints in the low 60s F beneath 7.5-8 C/km mid-level lapse rates will support over 2000 J/kg MLCAPE. Modest veering and strengthening of the vertical wind profile will contribute to 30-40 kts of effective bulk shear and modestly elongated hodographs. Some of the stronger multicells and transient supercells may yield a risk for large hail and severe gusts beginning mid afternoon through the early evening. ...North Carolina into the Northeast... At least scattered thunderstorms will develop amid weak vertical wind shear this afternoon ahead of a cold front. Pulse cellular and occasional multicells are the expected storm mode. Rich low-level moisture preceding the front will contribute to 1000-2000 J/kg MLCAPE, which may support a few strong, potentially damaging gusts with some of the stronger storms. ...North Florida... A couple of strong thunderstorms may develop along the trailing portion of a cold front by afternoon. Similar to the Northeast, rich low-level moisture will promote 2000-3000 J/kg MLCAPE, fostering wet downburst/strong wind gust potential with pulse single cells and multicells. ...Sabine River Valley... Ongoing clusters of weak thunderstorms moving southward on the backside of the Eastern U.S. mid-level trough will likely continue southward through the Sabine River Valley today. Although the 12 UTC Lake Charles raob is characterized as only weakly unstable, additional heating will result in moderate destabilization by midday. A localized wind-damage risk may accompany the stronger outflow surges before this activity moves into the northwest Gulf. ..Smith/Mosier.. 08/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon Aug 19 2024 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF WESTERN INTO NORTH-CENTRAL MONTANA...EASTERN MONTANA...AND EASTERN COLORADO... ...SUMMARY... Scattered severe thunderstorms are possible across portions of Montana and eastern Colorado during the afternoon and evening. Large hail and severe gusts are the primary hazards. ...Synopsis... Water-vapor imagery this morning shows a mid- to upper-level ridge situated over the south-central High Plains northward through the northern Great Plains. A mid-level trough is over the East and a mid-level low and associated trough are over the eastern Pacific to the west of the Pacific Northwest. ...Portions of the central and northern Rockies/High Plains... Broad 40+ kt southwesterly 500 mb flow will overspread portions of the central into the northern Rockies as an impulse embedded in the West Coast mid-level trough grazes the region. Isolated to scattered thunderstorms are forecast across Montana with locally greater thunderstorm coverage forecast over western into north-central MT this afternoon and evening, and separately over portions of eastern Montana. Richer moisture is evident in morning surface analysis across eastern MT where lower 60s F surface dewpoints are present with mid 50s farther west near the I-15 corridor. Consequently, greater buoyancy is expected later this afternoon over eastern MT with 2000+ J/kg MLCAPE possible with 750-1250 J/kg farther west. Given the deep boundary layer and corresponding steep lapse rates in both areas, severe gusts are possible with the more intense cells and clusters, especially if a linear cluster can evolve near the Rocky Mtn Front and push northeastward into the High Plains. Elsewhere, isolated instances of hail/wind may accompany the stronger thunderstorms from the eastern Great Basin northward into ID/WY. ...Eastern Colorado... Moist upslope flow during peak surface heating will result in thunderstorm initiation off of the higher terrain. Surface dewpoints in the low 60s F beneath 7.5-8 C/km mid-level lapse rates will support over 2000 J/kg MLCAPE. Modest veering and strengthening of the vertical wind profile will contribute to 30-40 kts of effective bulk shear and modestly elongated hodographs. Some of the stronger multicells and transient supercells may yield a risk for large hail and severe gusts beginning mid afternoon through the early evening. ...North Carolina into the Northeast... At least scattered thunderstorms will develop amid weak vertical wind shear this afternoon ahead of a cold front. Pulse cellular and occasional multicells are the expected storm mode. Rich low-level moisture preceding the front will contribute to 1000-2000 J/kg MLCAPE, which may support a few strong, potentially damaging gusts with some of the stronger storms. ...North Florida... A couple of strong thunderstorms may develop along the trailing portion of a cold front by afternoon. Similar to the Northeast, rich low-level moisture will promote 2000-3000 J/kg MLCAPE, fostering wet downburst/strong wind gust potential with pulse single cells and multicells. ...Sabine River Valley... Ongoing clusters of weak thunderstorms moving southward on the backside of the Eastern U.S. mid-level trough will likely continue southward through the Sabine River Valley today. Although the 12 UTC Lake Charles raob is characterized as only weakly unstable, additional heating will result in moderate destabilization by midday. A localized wind-damage risk may accompany the stronger outflow surges before this activity moves into the northwest Gulf. ..Smith/Mosier.. 08/19/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0351 AM CDT Mon Aug 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... ...Thursday/Day 4 to Saturday/Day 6... An upper-level ridge is forecast to gradually build over the Great Plains from Thursday to Saturday. During this time period, an axis of low-level moisture and instability is forecast to remain over the central and northern Plains. As surface temperatures warm each day, isolated thunderstorms are expected to develop over parts of the moist airmass. Moderate deep-layer shear and steep lapse rates should be favorable for a severe threat, with large hail and severe wind gusts possible. However, large-scale ascent and the resultant convective coverage is forecast to be limited, which should reduce the overall severe threat coverage. ...Sunday/Day7 and Monday/Day 8... An upper-level low over the Desert Southwest is forecast by the ECMWF to move quickly northeastward across the Intermountain West on Sunday, and into the northern Plains on Monday. Ahead of this feature, the medium range models suggest that a broad corridor of strong instability will be in place. Although convective coverage may remain relatively isolated on Sunday and Monday, the strong instability should be favorable for a severe threat. Large hail and isolated severe wind gusts would be possible in the northern Plains on Sunday, and in the upper Mississippi Valley on Monday. However, there is a wide dispersion of solutions concerning the timing of the upper-level trough. This suggest that uncertainty is substantial from Sunday into Monday. Once the models become in better agreement, a threat area may need to be considered early next week if it appears that convective coverage over the warm sector will be sufficient. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0351 AM CDT Mon Aug 19 2024 Valid 221200Z - 271200Z ...DISCUSSION... ...Thursday/Day 4 to Saturday/Day 6... An upper-level ridge is forecast to gradually build over the Great Plains from Thursday to Saturday. During this time period, an axis of low-level moisture and instability is forecast to remain over the central and northern Plains. As surface temperatures warm each day, isolated thunderstorms are expected to develop over parts of the moist airmass. Moderate deep-layer shear and steep lapse rates should be favorable for a severe threat, with large hail and severe wind gusts possible. However, large-scale ascent and the resultant convective coverage is forecast to be limited, which should reduce the overall severe threat coverage. ...Sunday/Day7 and Monday/Day 8... An upper-level low over the Desert Southwest is forecast by the ECMWF to move quickly northeastward across the Intermountain West on Sunday, and into the northern Plains on Monday. Ahead of this feature, the medium range models suggest that a broad corridor of strong instability will be in place. Although convective coverage may remain relatively isolated on Sunday and Monday, the strong instability should be favorable for a severe threat. Large hail and isolated severe wind gusts would be possible in the northern Plains on Sunday, and in the upper Mississippi Valley on Monday. However, there is a wide dispersion of solutions concerning the timing of the upper-level trough. This suggest that uncertainty is substantial from Sunday into Monday. Once the models become in better agreement, a threat area may need to be considered early next week if it appears that convective coverage over the warm sector will be sufficient. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Mon Aug 19 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered thunderstorms, associated with large hail and severe wind gusts, will be possible on Wednesday across parts of the northern High Plains. Marginally severe storms will be possible westward into central Montana and southward into the central High Plains. ...Central and Northern High Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a mid-level shortwave trough moves northeastward across the northern Rockies. An axis of maximized low-level moisture is forecast from central Nebraska into central South Dakota and northwestward into northeast Montana, where surface dewpoints will likely be in the 60s F. Moderate to strong instability appears likely to develop along and near parts of the moist axis by afternoon. Both the NAM and ECMWF have MLCAPE peaking above 3000 J/kg in parts of the northern Plains, with the ECMWF showing an axis of strong instability by late afternoon. As the airmass destabilizes, isolated convective initiation will be possible near the moist axis. Additional storms will likely develop in the higher terrain of northern Wyoming and southern Montana. This convection is expected to move northeastward into the northern High Plains during the late afternoon and early evening as the shortwave trough approaches from the southwest. Forecast soundings over western North Dakota and far eastern Montana have 0-6 km shear in the 40 to 50 knot range, with steep low to mid-level lapse rates exceeding 8 C/km in some areas. The instability and shear would support supercells with isolated large hail and severe wind gusts. The models suggest that the severe threat would persist into the early to mid evening as the shortwave trough moves across the region. Further south in the central High Plains, isolated to scattered thunderstorms are expected to develop near the instability axis during the late afternoon. A potential for isolated large hail and severe wind gusts would be possible. However, deep-layer shear and large-ascent are forecast to be weaker in the central High Plains, suggesting any threat should remain marginal. ..Broyles.. 08/19/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...Synopsis... The West Coast mid-level trough will slowly progress eastward tomorrow (Tuesday), with strong southwesterly 500 mb flow expected to overspread the Great Basin. Similar to Day 1 (today), afternoon boundary-layer mixing will promote dry and windy conditions along the Oregon/California/Nevada border, as well as southwestern into central Nevada, where Elevated highlights have been added. ..Squitieri.. 08/19/2024 ...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 0158 AM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...Synopsis... The West Coast mid-level trough will slowly progress eastward tomorrow (Tuesday), with strong southwesterly 500 mb flow expected to overspread the Great Basin. Similar to Day 1 (today), afternoon boundary-layer mixing will promote dry and windy conditions along the Oregon/California/Nevada border, as well as southwestern into central Nevada, where Elevated highlights have been added. ..Squitieri.. 08/19/2024 ...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 0157 AM CDT Mon Aug 19 2024 Valid 191200Z - 201200Z ...Synopsis... Strong southwesterly mid-level flow will overspread the Interior West as a mid-level trough meanders over the West Coast and an upper ridge persists over the central U.S. today. Boundary-layer mixing to the lee of the Sierra will promote windy conditions amid 10-20 percent RH by afternoon. Elevated highlights have been maintained across portions of the Harney Basin in southeast Oregon and adjacent areas, as well as southwest into central Nevada, where the aforementioned dry and windy conditions should persist for several hours atop fuels receptive to wildfire spread. ..Squitieri.. 08/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more