MD 1886 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHEASTERN WYOMING INTO NORTHEAST/NORTH-CENTRAL COLORADO
Mesoscale Discussion 1886 NWS Storm Prediction Center Norman OK 0205 PM CDT Mon Aug 12 2024 Areas affected...Portions of southeastern Wyoming into northeast/north-central Colorado Concerning...Severe potential...Watch unlikely Valid 121905Z - 122100Z Probability of Watch Issuance...20 percent SUMMARY...The potential for isolated large hail and strong to locally severe gusts will gradually increase through the afternoon. The overall severe threat appears too marginal/localized for a watch. DISCUSSION...Latest day cloud phase satellite imagery indicates deepening boundary-layer cumulus along the Front Range and northward along the higher terrain into southeastern WY. Isolated thunderstorms have initiated in southeastern WY, where diurnal heating has eroded inhibition locally. Over the next several hours, continued heating amid upper 50s/lower 60s dewpoints should favor additional thunderstorm development along the higher terrain, before spreading eastward into the richer boundary-layer moisture. Sufficient (albeit weak) surface-based instability and effective shear increasing to around 30-40 kt could promote a few organized storms, including the potential for a supercell or two. Severe hail (generally up to 1.5 inches) and strong to locally severe gusts are possible with any longer-lived storms. However, current thinking is that the severe risk will be too localized/marginal for a watch. ..Weinman/Mosier.. 08/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOU...CYS... LAT...LON 41330521 41880499 42050473 42160446 42120411 41690403 39440430 39220457 39240489 39450515 40190525 41330521 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0327 PM CDT Mon Aug 12 2024 Valid 141200Z - 201200Z The potential for widespread critical fire weather conditions remains low through the extended period. Long-range ensemble guidance continues to suggest mean troughing will become established along the West Coast with upper ridging over the southern and central CONUS through the work week and into next weekend. This synoptic regime will favor widespread rain/thunderstorm chances for much of the country with the exception of NV/CA and portions of central TX. ...D4/Thursday - Pacific Northwest... The evolving synoptic regime will favor multiple weak upper disturbances propagating across the northern Great Basin as an upper low slowly amplifies off the West Coast through the work week and into the upcoming weekend. Multiple runs from the GFS/ECMWF/Canadian model families (and associated ensembles) have shown a consistent signal for convection across portions of OR on D4/Thursday as one such disturbances moves across the region. While the probability for convection is somewhat meager (around 40% based on blended ensemble guidance), forecast PWAT values and QPF probabilities suggest that thunderstorms that do development may be dry and pose a fire weather concern given antecedent dry fuels and recent lighting starts across this region. Low (10%) risk highlights have been introduced to address this concern. ...Great Basin... The evolving synoptic regime will favor multiple weak upper disturbances propagating across the northern Great Basin as an upper low slowly amplifies off the West Coast through the work week and into the upcoming weekend. This will support multiple days of breezy conditions across the Great Basin - primarily across NV - where conditions should remain dry (RH in the low teens to low 20s) within a persistent downslope flow regime off the Sierra Nevada. Areas of elevated fire weather conditions appear possible each day, but the synoptic regime will favor weak low-level mass responses and modest surface winds. ...Texas... Ensemble guidance continues to show a strong signal for dry conditions and afternoon high temperatures returning into the low 100s through the upcoming weekend. These hot/dry conditions will support drying most fuels, especially grasses across west to northwest TX where the hottest conditions are expected. The building upper ridge will limit the potential for widespread, strong gradient winds, but trends forecast wind speeds and fuels will be monitored. ..Moore.. 08/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0327 PM CDT Mon Aug 12 2024 Valid 141200Z - 201200Z The potential for widespread critical fire weather conditions remains low through the extended period. Long-range ensemble guidance continues to suggest mean troughing will become established along the West Coast with upper ridging over the southern and central CONUS through the work week and into next weekend. This synoptic regime will favor widespread rain/thunderstorm chances for much of the country with the exception of NV/CA and portions of central TX. ...D4/Thursday - Pacific Northwest... The evolving synoptic regime will favor multiple weak upper disturbances propagating across the northern Great Basin as an upper low slowly amplifies off the West Coast through the work week and into the upcoming weekend. Multiple runs from the GFS/ECMWF/Canadian model families (and associated ensembles) have shown a consistent signal for convection across portions of OR on D4/Thursday as one such disturbances moves across the region. While the probability for convection is somewhat meager (around 40% based on blended ensemble guidance), forecast PWAT values and QPF probabilities suggest that thunderstorms that do development may be dry and pose a fire weather concern given antecedent dry fuels and recent lighting starts across this region. Low (10%) risk highlights have been introduced to address this concern. ...Great Basin... The evolving synoptic regime will favor multiple weak upper disturbances propagating across the northern Great Basin as an upper low slowly amplifies off the West Coast through the work week and into the upcoming weekend. This will support multiple days of breezy conditions across the Great Basin - primarily across NV - where conditions should remain dry (RH in the low teens to low 20s) within a persistent downslope flow regime off the Sierra Nevada. Areas of elevated fire weather conditions appear possible each day, but the synoptic regime will favor weak low-level mass responses and modest surface winds. ...Texas... Ensemble guidance continues to show a strong signal for dry conditions and afternoon high temperatures returning into the low 100s through the upcoming weekend. These hot/dry conditions will support drying most fuels, especially grasses across west to northwest TX where the hottest conditions are expected. The building upper ridge will limit the potential for widespread, strong gradient winds, but trends forecast wind speeds and fuels will be monitored. ..Moore.. 08/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Aug 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE COASTAL CAROLINAS...CENTRAL HIGH PLAINS...EASTERN GREAT BASIN NORTHWARD INTO PARTS OF THE NORTH-CENTRAL ROCKIES...AND NORTHERN MONTANA... ...SUMMARY... Isolated severe thunderstorms are possible today over parts of the coastal Carolinas, central High Plains, the eastern Great Basin northward into parts of the north-central Rockies, and northern Montana. ...20z Update... No changes are needed to the Day 1 Outlook. Marginal risk for strong to severe gusts and large hail will continue through the afternoon across the central High Plains/Central Plains as well as the Intermountain West into the northern High Plains. See MCD#1186 and MCD#1885 for more information. Additional thunderstorm development is expected across a front portions of South Carolina this afternoon. Ahead of this boundary, the air mass has destabilized, with around 2000 J/kg of MLCAPE and 20-30 kts of deep layer shear. Thunderstorms will be capable of instances of strong to severe wind. ..Thornton/Mosier.. 08/12/2024 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 12 2024/ ...Central High Plains/Central Plains... Upslope flow will persist across the central High Plains, helping to maintain moderate low-level moisture across region. Afternoon dewpoints are expected to range from the upper 60s in the southeast CO/northeast NM/western Panhandles vicinity to the mid to upper 50s across eastern WY. This low-level moisture will help support moderate buoyancy during the afternoon/evening, although some limited capping may linger. Thunderstorms are expected to develop across the higher terrain before then progressing eastward into the more moist and buoyant airmass downstream. Generally moderate deep-layer vertical shear coupled with the potential for some remaining convective inhibition suggest the severe potential will remain isolated, with damaging gusts and/or large hail as the primary severe risks. Thunderstorms will likely persist eastward into more of the central Plains, supported by moderate buoyancy and shear and the development of modest low-level jet. Isolated instances of large hail are possible, but the overall storm severity will likely be tempered by limited instability. ...Intermountain West into the Northern High Plains... Morning satellite imagery depicts upper ridging centered over TX covering much of the southern third of the CONUS and also extending northward into MT. Several shortwave troughs are moving through the westerlies within the northern periphery of this ridging, including a low-amplitude shortwave currently moving into ID and northern/central NV and another, more defined shortwave farther west off the northern CA coast. Eastward/northeastward progression of these waves will bring greater mid-level moisture and increased large-scale forcing for ascent, supporting the development of scattered to numerous thunderstorms across the region. Mid-level flow will remain modest, but a few more organized/persistent updrafts are possible. High cloud bases atop steep low-level lapse rates could result in a few stronger gusts as these more persistent storms form into clusters, particularly from northern/central UT into far eastern ID and far western WY and northern MT. ...Coastal Carolinas... Far southern periphery of an upper trough currently extending from Quebec through the Upper OH Valley will glance this region today as it progresses eastward. Modest (i.e. 20-30kt) mid-level flow will overspread a moisture-rich airmass (i.e. PWs over 2") in place south of a front. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. A few water-loaded downbursts capable of damaging gusts could be noted with the strongest storms. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Mon Aug 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE COASTAL CAROLINAS...CENTRAL HIGH PLAINS...EASTERN GREAT BASIN NORTHWARD INTO PARTS OF THE NORTH-CENTRAL ROCKIES...AND NORTHERN MONTANA... ...SUMMARY... Isolated severe thunderstorms are possible today over parts of the coastal Carolinas, central High Plains, the eastern Great Basin northward into parts of the north-central Rockies, and northern Montana. ...20z Update... No changes are needed to the Day 1 Outlook. Marginal risk for strong to severe gusts and large hail will continue through the afternoon across the central High Plains/Central Plains as well as the Intermountain West into the northern High Plains. See MCD#1186 and MCD#1885 for more information. Additional thunderstorm development is expected across a front portions of South Carolina this afternoon. Ahead of this boundary, the air mass has destabilized, with around 2000 J/kg of MLCAPE and 20-30 kts of deep layer shear. Thunderstorms will be capable of instances of strong to severe wind. ..Thornton/Mosier.. 08/12/2024 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 12 2024/ ...Central High Plains/Central Plains... Upslope flow will persist across the central High Plains, helping to maintain moderate low-level moisture across region. Afternoon dewpoints are expected to range from the upper 60s in the southeast CO/northeast NM/western Panhandles vicinity to the mid to upper 50s across eastern WY. This low-level moisture will help support moderate buoyancy during the afternoon/evening, although some limited capping may linger. Thunderstorms are expected to develop across the higher terrain before then progressing eastward into the more moist and buoyant airmass downstream. Generally moderate deep-layer vertical shear coupled with the potential for some remaining convective inhibition suggest the severe potential will remain isolated, with damaging gusts and/or large hail as the primary severe risks. Thunderstorms will likely persist eastward into more of the central Plains, supported by moderate buoyancy and shear and the development of modest low-level jet. Isolated instances of large hail are possible, but the overall storm severity will likely be tempered by limited instability. ...Intermountain West into the Northern High Plains... Morning satellite imagery depicts upper ridging centered over TX covering much of the southern third of the CONUS and also extending northward into MT. Several shortwave troughs are moving through the westerlies within the northern periphery of this ridging, including a low-amplitude shortwave currently moving into ID and northern/central NV and another, more defined shortwave farther west off the northern CA coast. Eastward/northeastward progression of these waves will bring greater mid-level moisture and increased large-scale forcing for ascent, supporting the development of scattered to numerous thunderstorms across the region. Mid-level flow will remain modest, but a few more organized/persistent updrafts are possible. High cloud bases atop steep low-level lapse rates could result in a few stronger gusts as these more persistent storms form into clusters, particularly from northern/central UT into far eastern ID and far western WY and northern MT. ...Coastal Carolinas... Far southern periphery of an upper trough currently extending from Quebec through the Upper OH Valley will glance this region today as it progresses eastward. Modest (i.e. 20-30kt) mid-level flow will overspread a moisture-rich airmass (i.e. PWs over 2") in place south of a front. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. A few water-loaded downbursts capable of damaging gusts could be noted with the strongest storms. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0228 PM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z An isolated dry thunderstorm risk area has been introduced to portions of eastern OR into ID. Isolated thunderstorms will likely be ongoing at the start of the period across far eastern OR, and should migrate eastward over the central ID mountains through the afternoon with little in the way of wetting rainfall given fast storm motions. A second round of convection remains possible during the late afternoon across southeast OR/southwest ID, and will likely feature dry convection given forecast PWAT values at/below 0.6 inch. While ensemble guidance has trended towards higher probability for this to occur, the overall signal remains fairly weak. ..Moore.. 08/12/2024 .PREV DISCUSSION... /ISSUED 1252 AM CDT Mon Aug 12 2024/ ...Synopsis... On Tuesday, the upper trough will lift out of the northern Great Basin and into the northern High Plains, all while losing amplitude. While some increase in mid-level winds may occur over the Great Basin, this will not occur until late in the period. At the surface, the pressure pattern will be more disorganized than Monday and stronger winds will likely be diurnally/terrain-driven. ...Nevada... Areas of locally elevated fire weather are possible as RH will still fall to 15-20% during the afternoon. Slightly stronger winds appear possible in southern Nevada, but fuels are also less receptive than farther north. Sustained elevated conditions are not currently expected. ...Central Idaho... With the mid-level trough moving through early in the period, mid/upper-level cloud cover will be possible. This may impact destabilization enough to reduce potential storm coverage during the afternoon. Should storms occur, some could be dry. Confidence in coverage is too low for highlights. ...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 0228 PM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z An isolated dry thunderstorm risk area has been introduced to portions of eastern OR into ID. Isolated thunderstorms will likely be ongoing at the start of the period across far eastern OR, and should migrate eastward over the central ID mountains through the afternoon with little in the way of wetting rainfall given fast storm motions. A second round of convection remains possible during the late afternoon across southeast OR/southwest ID, and will likely feature dry convection given forecast PWAT values at/below 0.6 inch. While ensemble guidance has trended towards higher probability for this to occur, the overall signal remains fairly weak. ..Moore.. 08/12/2024 .PREV DISCUSSION... /ISSUED 1252 AM CDT Mon Aug 12 2024/ ...Synopsis... On Tuesday, the upper trough will lift out of the northern Great Basin and into the northern High Plains, all while losing amplitude. While some increase in mid-level winds may occur over the Great Basin, this will not occur until late in the period. At the surface, the pressure pattern will be more disorganized than Monday and stronger winds will likely be diurnally/terrain-driven. ...Nevada... Areas of locally elevated fire weather are possible as RH will still fall to 15-20% during the afternoon. Slightly stronger winds appear possible in southern Nevada, but fuels are also less receptive than farther north. Sustained elevated conditions are not currently expected. ...Central Idaho... With the mid-level trough moving through early in the period, mid/upper-level cloud cover will be possible. This may impact destabilization enough to reduce potential storm coverage during the afternoon. Should storms occur, some could be dry. Confidence in coverage is too low for highlights. ...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 1230 PM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE GREAT BASIN INTO THE NORTHERN/CENTRAL ROCKIES AND ADJACENT HIGH PLAINS AND ACROSS SOUTHERN NEBRASKA AND NORTHERN KANSAS TO NORTHWEST MISSOURI...AND ACROSS MUCH OF CENTRAL AND EASTERN SOUTH CAROLINA... ...SUMMARY... Isolated severe thunderstorms are possible Tuesday across parts of the eastern Great Basin into the northern/central High Plains and central Plains, as well as portions of South Carolina and vicinity. ...Synopsis... On Tuesday, the larger-scale pattern will feature a mid-level trough on the West Coast with a ridge across the central CONUS and a positively tilted trough along the east coast. This pattern will shift east with the mid-level ridge strengthening through the period. However, despite the strengthening ridge, some weak mid-level perturbations within the flow will likely be a catalyst for thunderstorm development from eastern Colorado, across the Plains, and into northwest Missouri Tuesday night. ...Eastern Great Basin to the Northern/Central High Plains... Broad height falls ahead of a mid-level shortwave trough moving from the Great Basin to the Northern Rockies will lead to widespread thunderstorm development on Tuesday. The greatest instability, and thus potential for more robust updrafts will exist from eastern Utah into eastern Idaho and western Wyoming. 35 to 40 knots of shear should be sufficient for a few supercells capable of large hail in this region. Elsewhere, severe-wind gusts will be the primary threat amid high-based convection promoting strong downdraft production. An additional area of focused convection will exist across eastern Colorado into eastern Wyoming and the Nebraska Panhandle. Convection will first develop across the higher terrain before into moderate instability across the Plains. Mid-level flow will be relatively weak closer to the ridge axis, but 50 knot southwesterly flow is forecast above 400mb which should help organize the stronger storms and lead to a threat for some supercells capable of large hail and severe wind gusts. There is a consistent signal that storms may congeal into a MCS across northeast Colorado and move across southern Nebraska during the overnight period. The strengthening low-level jet should maintain this MCS and forecast soundings show sufficient instability/shear for some isolated severe threat during the overnight period. ...South Carolina... A cold front will linger across South Carolina on Tuesday with mid 70s dewpoints south of it. This will allow for moderate destabilization ahead of a mid-level shortwave trough which will approach during the day. Warm mid-level temperatures and thus, weak mid-level lapse rates will be the primary limiting factor for severe storms. However, there will be sufficient instability 1000-2000 J/kg and moderate shear 40-45 knots which may allow for isolated strong to severe storms. Given the warm temperatures aloft, the primary threat will be damaging wind. ...Southeast Nebraska/northeast Kansas into northwest Missouri... Tuesday night, a low-level jet will strengthen to 40 to 45 knots across the central Plains amid a very moist environment. As isentropic ascent increases early Wednesday morning, MUCAPE will increase to near 3000 J/kg. Westerly effective shear is forecast around 35 knots which will be sufficient for some storm organization including the potential for a few supercell structures. While heavy rain will likely be the primary threat, some large hail or severe wind may be possible. ..Bentley.. 08/12/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Aug 12 2024 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE GREAT BASIN INTO THE NORTHERN/CENTRAL ROCKIES AND ADJACENT HIGH PLAINS AND ACROSS SOUTHERN NEBRASKA AND NORTHERN KANSAS TO NORTHWEST MISSOURI...AND ACROSS MUCH OF CENTRAL AND EASTERN SOUTH CAROLINA... ...SUMMARY... Isolated severe thunderstorms are possible Tuesday across parts of the eastern Great Basin into the northern/central High Plains and central Plains, as well as portions of South Carolina and vicinity. ...Synopsis... On Tuesday, the larger-scale pattern will feature a mid-level trough on the West Coast with a ridge across the central CONUS and a positively tilted trough along the east coast. This pattern will shift east with the mid-level ridge strengthening through the period. However, despite the strengthening ridge, some weak mid-level perturbations within the flow will likely be a catalyst for thunderstorm development from eastern Colorado, across the Plains, and into northwest Missouri Tuesday night. ...Eastern Great Basin to the Northern/Central High Plains... Broad height falls ahead of a mid-level shortwave trough moving from the Great Basin to the Northern Rockies will lead to widespread thunderstorm development on Tuesday. The greatest instability, and thus potential for more robust updrafts will exist from eastern Utah into eastern Idaho and western Wyoming. 35 to 40 knots of shear should be sufficient for a few supercells capable of large hail in this region. Elsewhere, severe-wind gusts will be the primary threat amid high-based convection promoting strong downdraft production. An additional area of focused convection will exist across eastern Colorado into eastern Wyoming and the Nebraska Panhandle. Convection will first develop across the higher terrain before into moderate instability across the Plains. Mid-level flow will be relatively weak closer to the ridge axis, but 50 knot southwesterly flow is forecast above 400mb which should help organize the stronger storms and lead to a threat for some supercells capable of large hail and severe wind gusts. There is a consistent signal that storms may congeal into a MCS across northeast Colorado and move across southern Nebraska during the overnight period. The strengthening low-level jet should maintain this MCS and forecast soundings show sufficient instability/shear for some isolated severe threat during the overnight period. ...South Carolina... A cold front will linger across South Carolina on Tuesday with mid 70s dewpoints south of it. This will allow for moderate destabilization ahead of a mid-level shortwave trough which will approach during the day. Warm mid-level temperatures and thus, weak mid-level lapse rates will be the primary limiting factor for severe storms. However, there will be sufficient instability 1000-2000 J/kg and moderate shear 40-45 knots which may allow for isolated strong to severe storms. Given the warm temperatures aloft, the primary threat will be damaging wind. ...Southeast Nebraska/northeast Kansas into northwest Missouri... Tuesday night, a low-level jet will strengthen to 40 to 45 knots across the central Plains amid a very moist environment. As isentropic ascent increases early Wednesday morning, MUCAPE will increase to near 3000 J/kg. Westerly effective shear is forecast around 35 knots which will be sufficient for some storm organization including the potential for a few supercell structures. While heavy rain will likely be the primary threat, some large hail or severe wind may be possible. ..Bentley.. 08/12/2024 Read more

No Mesoscale Discussions are in effect as of Mon Aug 12 17:35:01 UTC 2024.

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Mon Aug 12 2024 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE COASTAL CAROLINAS...CENTRAL HIGH PLAINS...THE EASTERN GREAT BASIN NORTHWARD INTO PARTS OF THE NORTH-CENTRAL ROCKIES...AND NORTHERN MONTANA... ...SUMMARY... Isolated severe thunderstorms are possible today over parts of the coastal Carolinas, central High Plains, the eastern Great Basin northward into parts of the north-central Rockies, and northern Montana. ...Central High Plains/Central Plains... Upslope flow will persist across the central High Plains, helping to maintain moderate low-level moisture across region. Afternoon dewpoints are expected to range from the upper 60s in the southeast CO/northeast NM/western Panhandles vicinity to the mid to upper 50s across eastern WY. This low-level moisture will help support moderate buoyancy during the afternoon/evening, although some limited capping may linger. Thunderstorms are expected to develop across the higher terrain before then progressing eastward into the more moist and buoyant airmass downstream. Generally moderate deep-layer vertical shear coupled with the potential for some remaining convective inhibition suggest the severe potential will remain isolated, with damaging gusts and/or large hail as the primary severe risks. Thunderstorms will likely persist eastward into more of the central Plains, supported by moderate buoyancy and shear and the development of modest low-level jet. Isolated instances of large hail are possible, but the overall storm severity will likely be tempered by limited instability. ...Intermountain West into the Northern High Plains... Morning satellite imagery depicts upper ridging centered over TX covering much of the southern third of the CONUS and also extending northward into MT. Several shortwave troughs are moving through the westerlies within the northern periphery of this ridging, including a low-amplitude shortwave currently moving into ID and northern/central NV and another, more defined shortwave farther west off the northern CA coast. Eastward/northeastward progression of these waves will bring greater mid-level moisture and increased large-scale forcing for ascent, supporting the development of scattered to numerous thunderstorms across the region. Mid-level flow will remain modest, but a few more organized/persistent updrafts are possible. High cloud bases atop steep low-level lapse rates could result in a few stronger gusts as these more persistent storms form into clusters, particularly from northern/central UT into far eastern ID and far western WY and northern MT. ...Coastal Carolinas... Far southern periphery of an upper trough currently extending from Quebec through the Upper OH Valley will glance this region today as it progresses eastward. Modest (i.e. 20-30kt) mid-level flow will overspread a moisture-rich airmass (i.e. PWs over 2") in place south of a front. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. A few water-loaded downbursts capable of damaging gusts could be noted with the strongest storms. ..Mosier.. 08/12/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Mon Aug 12 2024 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE COASTAL CAROLINAS...CENTRAL HIGH PLAINS...THE EASTERN GREAT BASIN NORTHWARD INTO PARTS OF THE NORTH-CENTRAL ROCKIES...AND NORTHERN MONTANA... ...SUMMARY... Isolated severe thunderstorms are possible today over parts of the coastal Carolinas, central High Plains, the eastern Great Basin northward into parts of the north-central Rockies, and northern Montana. ...Central High Plains/Central Plains... Upslope flow will persist across the central High Plains, helping to maintain moderate low-level moisture across region. Afternoon dewpoints are expected to range from the upper 60s in the southeast CO/northeast NM/western Panhandles vicinity to the mid to upper 50s across eastern WY. This low-level moisture will help support moderate buoyancy during the afternoon/evening, although some limited capping may linger. Thunderstorms are expected to develop across the higher terrain before then progressing eastward into the more moist and buoyant airmass downstream. Generally moderate deep-layer vertical shear coupled with the potential for some remaining convective inhibition suggest the severe potential will remain isolated, with damaging gusts and/or large hail as the primary severe risks. Thunderstorms will likely persist eastward into more of the central Plains, supported by moderate buoyancy and shear and the development of modest low-level jet. Isolated instances of large hail are possible, but the overall storm severity will likely be tempered by limited instability. ...Intermountain West into the Northern High Plains... Morning satellite imagery depicts upper ridging centered over TX covering much of the southern third of the CONUS and also extending northward into MT. Several shortwave troughs are moving through the westerlies within the northern periphery of this ridging, including a low-amplitude shortwave currently moving into ID and northern/central NV and another, more defined shortwave farther west off the northern CA coast. Eastward/northeastward progression of these waves will bring greater mid-level moisture and increased large-scale forcing for ascent, supporting the development of scattered to numerous thunderstorms across the region. Mid-level flow will remain modest, but a few more organized/persistent updrafts are possible. High cloud bases atop steep low-level lapse rates could result in a few stronger gusts as these more persistent storms form into clusters, particularly from northern/central UT into far eastern ID and far western WY and northern MT. ...Coastal Carolinas... Far southern periphery of an upper trough currently extending from Quebec through the Upper OH Valley will glance this region today as it progresses eastward. Modest (i.e. 20-30kt) mid-level flow will overspread a moisture-rich airmass (i.e. PWs over 2") in place south of a front. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. A few water-loaded downbursts capable of damaging gusts could be noted with the strongest storms. ..Mosier.. 08/12/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1046 AM CDT Mon Aug 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR WESTERN NEVADA... The primary forecast change for this update is an expansion of the dry-thunderstorm risk area across portions of the Pacific Northwest and northern Rockies. Morning soundings from BOI, OTX, and MFR all show cooler mid-level temperatures compared to the previous 24 hours, which should support thunderstorm chances today through tonight as lift associated with an approaching trough overspreads the region. GOES imagery also depicts a plume of 0.4 to 0.6 inch PWAT values across northern CA into central ID that was well sampled by the BOI sounding, and suggests a slightly better probability for dry thunderstorms exists through this corridor. A few lightning-related fire starts associated with a mix of wet/dry thunderstorms have been reported over the past 24 hours across WA and ID, and a lack of widespread wetting rainfall has maintained dry fuels that will support a continued fire weather concern for today and into the early morning hours Tuesday. Other minor adjustments include an expansion of the Elevated risk area into the Snake River Plain of eastern ID where ensemble guidance has shown a consistent signal for a few hours of dry conditions with 15-20 mph winds. See the previous discussion for additional details. ..Moore.. 08/12/2024 .PREV DISCUSSION... /ISSUED 0124 AM CDT Mon Aug 12 2024/ ...Synopsis... A shortwave trough within broader cyclonic flow in the Northwest will move through central California into western Nevada today. A surface trough in the Northwest/northern Rockies will promote dry and breezy conditions in parts of the northern Great Basin. ...Great Basin... Broadly elevated fire weather conditions are expected over much of Nevada into far southern Idaho. Winds of 15-20 mph will be the most common along with 10-20% RH during the afternoon. A small region of northwest Nevada may experience briefly critical conditions as both the terrain and the mid-level jet help to enhance surface winds to 20-25 mph. ...Northwest... Forcing for ascent from the upper trough will promote isolated thunderstorms from north-central California into central Idaho. With the mid-level jet more focused in northern Nevada, storm motions will not be overly fast. A mix of wet and dry thunderstorms are most probable. Recent CAM guidance also differs on the exact degree of coverage, but enough confidence in at least isolated activity is present for highlights. ...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 1046 AM CDT Mon Aug 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR WESTERN NEVADA... The primary forecast change for this update is an expansion of the dry-thunderstorm risk area across portions of the Pacific Northwest and northern Rockies. Morning soundings from BOI, OTX, and MFR all show cooler mid-level temperatures compared to the previous 24 hours, which should support thunderstorm chances today through tonight as lift associated with an approaching trough overspreads the region. GOES imagery also depicts a plume of 0.4 to 0.6 inch PWAT values across northern CA into central ID that was well sampled by the BOI sounding, and suggests a slightly better probability for dry thunderstorms exists through this corridor. A few lightning-related fire starts associated with a mix of wet/dry thunderstorms have been reported over the past 24 hours across WA and ID, and a lack of widespread wetting rainfall has maintained dry fuels that will support a continued fire weather concern for today and into the early morning hours Tuesday. Other minor adjustments include an expansion of the Elevated risk area into the Snake River Plain of eastern ID where ensemble guidance has shown a consistent signal for a few hours of dry conditions with 15-20 mph winds. See the previous discussion for additional details. ..Moore.. 08/12/2024 .PREV DISCUSSION... /ISSUED 0124 AM CDT Mon Aug 12 2024/ ...Synopsis... A shortwave trough within broader cyclonic flow in the Northwest will move through central California into western Nevada today. A surface trough in the Northwest/northern Rockies will promote dry and breezy conditions in parts of the northern Great Basin. ...Great Basin... Broadly elevated fire weather conditions are expected over much of Nevada into far southern Idaho. Winds of 15-20 mph will be the most common along with 10-20% RH during the afternoon. A small region of northwest Nevada may experience briefly critical conditions as both the terrain and the mid-level jet help to enhance surface winds to 20-25 mph. ...Northwest... Forcing for ascent from the upper trough will promote isolated thunderstorms from north-central California into central Idaho. With the mid-level jet more focused in northern Nevada, storm motions will not be overly fast. A mix of wet and dry thunderstorms are most probable. Recent CAM guidance also differs on the exact degree of coverage, but enough confidence in at least isolated activity is present for highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0723 AM CDT Mon Aug 12 2024 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE COASTAL CAROLINAS...CENTRAL HIGH PLAINS...THE EASTERN GREAT BASIN NORTHWARD INTO PARTS OF THE NORTH-CENTRAL ROCKIES...AND NORTHERN MONTANA... ...SUMMARY... Isolated severe thunderstorms are possible today over parts of the coastal Carolinas, central High Plains, the eastern Great Basin northward into parts of the north-central Rockies, and northern Montana. ...Rockies/Central High Plains Region... Water-vapor imagery this morning depicts a flattened upper anticyclone centered over east TX/LA and a large-scale trough over the WA/OR/northern CA coast. A notable mid-level disturbance will move from the eastern Pacific east-northeastward into northern NV during the period. Mid-level flow ahead of the western U.S. troughing will not be strong, but a plume of seasonably moist air from the Four Corners northward into MT will favor scattered to numerous thunderstorms developing this afternoon into the early evening. Heating will steepen 0-3 km lapse rates and promote severe gusts with the stronger outflow surges from UT northward along the ID/WY border. Recent model guidance also indicates widely scattered to scattered storms developing across northern MT and moving east as a small thunderstorm cluster. Localized severe gusts may accompany this activity before weakening by early to mid evening. Farther east over the central High Plains, the maintenance of moist/upslope flow into the High Plains and higher terrain (i.e., CO Front Range) will promote isolated to scattered storms developing around peak heating and moving into the adjacent High Plains. An isolated risk for large hail/severe gusts will be the primary hazards with the stronger storms. A cluster of storms will likely develop in response to a nocturnal intensification of a LLJ but waning instability by late evening will limit overall storm vigor. ...Coastal Carolinas... Southern influence of eastern US trough will glance this region today as a belt of 20-30kt mid-level flow overspreads a very moisture-rich airmass (i.e., mid to upper 70s deg F surface dewpoints) south of a front. Scattered thunderstorms should develop along this boundary by early afternoon then propagate toward and off the coast by early evening. Marginally severe gusts could be noted with the strongest storms. ..Smith/Jewell.. 08/12/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0345 AM CDT Mon Aug 12 2024 Valid 151200Z - 201200Z ...DISCUSSION... Medium-range guidance is in reasonably good agreement that another weak mid-level shortwave trough will move eastward across the northern/central Plains to the Upper Midwest on Day 4/Thursday. Some severe potential may accompany this feature, but forecast deep-layer shear should tend to remain rather marginal. Differences also exist in where a greater severe threat may develop across these regions, so a 15% severe area has not been included. Gradual amplification of the upper pattern should occur late this week into the upcoming weekend, with a trough/low developing over the eastern Pacific, ridging building over much of the western states into the Rockies/Plains, and troughing over the East. This pattern may support isolated severe potential each day from Day 5/Friday through early next week across parts of the central/eastern CONUS, generally along/south of a weak front and in a northwesterly mid-level flow regime between the upper ridge and eastern states upper trough. However, predictability of potential MCS corridors and greater severe potential remain low at this extended time frame. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS INTO THE MID MISSOURI VALLEY... ...SUMMARY... At least isolated severe thunderstorms may occur Wednesday across parts of the northern/central Plains into the mid Missouri Valley. ...Northern/Central Plains into the mid Missouri Valley... Generally elevated convection driven largely by low-level warm advection may be ongoing Wednesday morning from parts of the Dakotas southeastward to the Ozarks vicinity. This activity should weaken through the day as it spreads eastward into a less unstable airmass. In its wake, a fairly broad warm sector is forecast to be in place along/east of a weak lee surface trough and front extending north to south over much of the northern/central High Plains. Greater low-level moisture, with potentially upper 60s to mid 70s surface dewpoints, should be in place over portions of NE/KS into the mid MO Valley by late Wednesday afternoon. Daytime heating of this moist low-level airmass should encourage moderate to perhaps strong instability across this area. Large-scale forcing for ascent should remain fairly modest, as multiple low-amplitude mid-level perturbations emanate from the northern/central Rockies into the adjacent Plains through the period. Even though deep-layer shear is not expected to be overly strong, at least isolated robust thunderstorms with associated hail/wind threat appear possible across much of the northern/central Plains as these features move east-northeastward over the developing warm sector through the day. Some guidance shows potential for one or more clusters to develop/consolidate across parts of central/eastern NE/KS and vicinity Wednesday afternoon and evening. Greater instability and steeper low-level lapse rates should be in place across this area, which would potentially support more robust updrafts and cold pool consolidation with a somewhat better chance for severe/damaging winds. However, confidence in this scenario occurring is relatively low given weak forcing aloft. Have therefore opted to include a broad Marginal Risk for now across the northern/central Plains into the mid MO Valley. ..Gleason.. 08/12/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Aug 12 2024 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS INTO THE MID MISSOURI VALLEY... ...SUMMARY... At least isolated severe thunderstorms may occur Wednesday across parts of the northern/central Plains into the mid Missouri Valley. ...Northern/Central Plains into the mid Missouri Valley... Generally elevated convection driven largely by low-level warm advection may be ongoing Wednesday morning from parts of the Dakotas southeastward to the Ozarks vicinity. This activity should weaken through the day as it spreads eastward into a less unstable airmass. In its wake, a fairly broad warm sector is forecast to be in place along/east of a weak lee surface trough and front extending north to south over much of the northern/central High Plains. Greater low-level moisture, with potentially upper 60s to mid 70s surface dewpoints, should be in place over portions of NE/KS into the mid MO Valley by late Wednesday afternoon. Daytime heating of this moist low-level airmass should encourage moderate to perhaps strong instability across this area. Large-scale forcing for ascent should remain fairly modest, as multiple low-amplitude mid-level perturbations emanate from the northern/central Rockies into the adjacent Plains through the period. Even though deep-layer shear is not expected to be overly strong, at least isolated robust thunderstorms with associated hail/wind threat appear possible across much of the northern/central Plains as these features move east-northeastward over the developing warm sector through the day. Some guidance shows potential for one or more clusters to develop/consolidate across parts of central/eastern NE/KS and vicinity Wednesday afternoon and evening. Greater instability and steeper low-level lapse rates should be in place across this area, which would potentially support more robust updrafts and cold pool consolidation with a somewhat better chance for severe/damaging winds. However, confidence in this scenario occurring is relatively low given weak forcing aloft. Have therefore opted to include a broad Marginal Risk for now across the northern/central Plains into the mid MO Valley. ..Gleason.. 08/12/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 1 NWS Storm Prediction Center Norman OK 0124 AM CDT Mon Aug 12 2024 Valid 121200Z - 131200Z CORRECTED FOR HEADLINE ...CRITICAL FIRE WEATHER AREA FOR PARTS OF NORTHWEST NEVADA... ...Synopsis... A shortwave trough within broader cyclonic flow in the Northwest will move through central California into western Nevada today. A surface trough in the Northwest/northern Rockies will promote dry and breezy conditions in parts of the northern Great Basin. ...Great Basin... Broadly elevated fire weather conditions are expected over much of Nevada into far southern Idaho. Winds of 15-20 mph will be the most common along with 10-20% RH during the afternoon. A small region of northwest Nevada may experience briefly critical conditions as both the terrain and the mid-level jet help to enhance surface winds to 20-25 mph. ...Northwest... Forcing for ascent from the upper trough will promote isolated thunderstorms from north-central California into central Idaho. With the mid-level jet more focused in northern Nevada, storm motions will not be overly fast. A mix of wet and dry thunderstorms are most probable. Recent CAM guidance also differs on the exact degree of coverage, but enough confidence in at least isolated activity is present for highlights. ..Wendt.. 08/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook CORR 1 NWS Storm Prediction Center Norman OK 0124 AM CDT Mon Aug 12 2024 Valid 121200Z - 131200Z CORRECTED FOR HEADLINE ...CRITICAL FIRE WEATHER AREA FOR PARTS OF NORTHWEST NEVADA... ...Synopsis... A shortwave trough within broader cyclonic flow in the Northwest will move through central California into western Nevada today. A surface trough in the Northwest/northern Rockies will promote dry and breezy conditions in parts of the northern Great Basin. ...Great Basin... Broadly elevated fire weather conditions are expected over much of Nevada into far southern Idaho. Winds of 15-20 mph will be the most common along with 10-20% RH during the afternoon. A small region of northwest Nevada may experience briefly critical conditions as both the terrain and the mid-level jet help to enhance surface winds to 20-25 mph. ...Northwest... Forcing for ascent from the upper trough will promote isolated thunderstorms from north-central California into central Idaho. With the mid-level jet more focused in northern Nevada, storm motions will not be overly fast. A mix of wet and dry thunderstorms are most probable. Recent CAM guidance also differs on the exact degree of coverage, but enough confidence in at least isolated activity is present for highlights. ..Wendt.. 08/12/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more