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MD 1584 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FAR NORTHEASTERN MONTANA...WESTERN NORTH DAKOTA...AND FAR NORTHWESTERN SOUTH DAKOTA
Mesoscale Discussion 1584 NWS Storm Prediction Center Norman OK 0356 PM CDT Fri Jul 12 2024 Areas affected...Far northeastern Montana...western North Dakota...and far northwestern South Dakota Concerning...Severe potential...Watch unlikely Valid 122056Z - 122300Z Probability of Watch Issuance...20 percent SUMMARY...Widely scattered thunderstorms are expected to develop over the next 1-2 hours across portions of western ND, far northeastern MT, and far northwestern SD. Severe wind gusts near 65-76 mph, hail up to 1.5-2.0" in diameter, and perhaps a landspout tornado or two will be possible with the stronger thunderstorms. DISCUSSION...Diurnal heating across the northern plains has resulted in very warm temperatures in the low to upper 90s developing this afternoon. This, combined with surface dewpoints in the low 70s east of a surface trough/quasi-stationary warm front below steep mid-level lapse rates, is yielding 1500-3000 J/kg of MLCAPE. Recent satellite imagery shows increasing cumulus beginning to develop along the aforementioned trough. In addition, convective initiation has already taken place near Manning, ND. Increasing mid-level flow throughout late this afternoon into early this evening will likely support some thunderstorm organization and the potential for a few supercells. Thunderstorm coverage is expected to slowly increase late this afternoon, as destabilization continues under cooler temperatures aloft, subtle DCVA impacts the area, and surface convergence is enhanced. Considering large dewpoint-temperature spreads further west near the MT/ND border, damaging wind gusts appear more likely there, although a few instances of large hail cannot be ruled out through early this evening. Increasing low level helicity via backed surface flow with time, along with some enhanced stretching, could also support a landspout or two before sunset. Although a watch does not appear likely at this time due to an uncertainty in severe thunderstorm coverage, convective trends will be monitored closely over the next 1-2 hours. ..Barnes/Hart.. 07/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR...BYZ...GGW... LAT...LON 46920434 47680556 48480593 48910571 49010481 48990386 48920285 48320199 47280116 46220052 45280096 44920207 45570383 46920434 Read more

MD 1585 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR FAR NORTHEAST ARKANSAS INTO SOUTHERN ILLINOIS AND FAR SOUTHWEST INDIANA
Mesoscale Discussion 1585 NWS Storm Prediction Center Norman OK 0440 PM CDT Fri Jul 12 2024 Areas affected...Far northeast Arkansas into southern Illinois and far southwest Indiana Concerning...Severe potential...Watch unlikely Valid 122140Z - 122315Z Probability of Watch Issuance...5 percent SUMMARY...A localized threat for isolated hail and damaging winds may continue for the next 1-2 hours across far northeast Arkansas into southern Illinois and far southwest Indiana. In general, the severe threat is expected to wane heading into the evening hours. DISCUSSION...Regional radar composites and GOES visible imagery show a clear convective cold pool expanding across the lower OH River Valley region with convection largely struggling to remain sustained (largely owing to weak environmental shear and storm motions into the cold pool). However, over the past 30 minutes, a couple of brief, but relatively intense updrafts have been noted in IR cloud-top temperatures. MRMS hail metrics suggest hail may be approaching severe limits, and the overall thermodynamic environment on the periphery of the cold pool (characterized by over 2000 J/kg MLCAPE and somewhat steep lapse rates in the lowest 1-2 km) may support damaging downburst winds. Ambient lift along the outflow boundary and ahead of a weak MCV over southeast MO may support additional convection over the next 1-2 hours, but storm longevity (and the overall severe threat) is expected to remain fairly limited. ..Moore/Gleason.. 07/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IND...PAH...ILX...MEG...LSX...LZK...SGF... LAT...LON 38508743 38328771 37998802 37548811 37008821 36728848 36568909 36179004 36179077 36169121 36539134 36839120 37179041 37518984 37948958 38188946 38488942 38748915 38978878 39068847 39058804 38948760 38788743 38508743 Read more

MD 1586 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR THE NORTHERN/CENTRAL HIGH PLAINS
Mesoscale Discussion 1586 NWS Storm Prediction Center Norman OK 0444 PM CDT Fri Jul 12 2024 Areas affected...the northern/central High Plains Concerning...Severe potential...Watch unlikely Valid 122144Z - 122315Z Probability of Watch Issuance...5 percent SUMMARY...Sporadic and highly localized severe wind gusts will be possible within dry microbursts from northeast Wyoming and western South Dakota into northeast Colorado through sunset. DISCUSSION...Isolated high-based, low-topped convection is underway adjacent to the Big Horns, north of the Black Hills, and into northeast Colorado along a lee thermal trough. Surface-temperature dew point spreads where convection is initiating are around 50-55 F, indicative of a deeply mixed boundary layer over the High Plains. As such, MLCAPE values are largely around the 500-1000 J/kg where convection is forming, but do increase with eastern extent towards the lower plains. This initial activity is expected to struggle to substantially deepen given the airmass, yielded a predominant dry microburst wind threat across the region for the first few hours of development. Moderate northwesterly speed shear within the cloud-bearing layer may promote small hail production in the strongest cores, which could augment downdrafts as they fall. ..Grams/Gleason.. 07/12/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU...CYS...BYZ...RIW... LAT...LON 44860624 45350520 45210270 44800166 43000163 40150186 39950224 40010280 40490305 43140425 44080647 44860624 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN PLAINS...A SMALL PART OF THE LOWER OHIO VALLEY INTO NORTHERN ARKANSAS...AND A SMALL PART OF NORTHWEST ARIZONA... ...SUMMARY... Isolated severe wind and hail will be possible over the northern and central Great Plains from late afternoon into tonight, and this afternoon from the Ozarks to lower Ohio Valley. A Marginal Risk remains in effect for parts of the northern Plains. Storms will form later this afternoon within the surface trough near the eastern borders of MT and WY, with locally severe gusts or marginal hail possible. Additional storms may move across eastern ND into northwest MN late tonight into early Saturday morning, as the SK/MB upper trough skirts the area. To the southwest, isolated storms that develop over northern parts of the Mogollon Rim may produce localized strong gusts later this afternoon as outflows push southwestward into the deeply mixed boundary layer. Precipitable water values up to 0.75" should be sufficient for outflow production with a general west/southwest motion. ..Jewell.. 07/12/2024 .PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 12 2024/ ...Northern Plains... Broad diffluent northwesterly mid-level flow is present today across the northern Plains states. Full sunshine over the region will result in hot surface temperatures and inverted-v thermodynamic profiles from eastern MT/WY into the western Dakotas. Most morning CAM solutions suggest scattered high-based thunderstorm development by late afternoon, with activity spreading slowly eastward through the evening. Locally gusty/damaging winds are the main concern with these storms. Greater instability exists farther east in ND/SD/NE but will remain capped in most areas, unless congealing outflow from the west can intercept the higher theta-e air with some risk of wind/hail in the strongest cells. ...Southern MO/IL... Morning visible satellite imagery shows a remnant MCV over southern MO tracking slowly eastward. Ample low-level moisture and CAPE ahead of this system will likely result in scattered afternoon thunderstorms. Winds aloft are relatively weak, and convection should remain rather disorganized. However, the strongest storms could pose a risk of locally gusty winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN PLAINS...A SMALL PART OF THE LOWER OHIO VALLEY INTO NORTHERN ARKANSAS...AND A SMALL PART OF NORTHWEST ARIZONA... ...SUMMARY... Isolated severe wind and hail will be possible over the northern and central Great Plains from late afternoon into tonight, and this afternoon from the Ozarks to lower Ohio Valley. A Marginal Risk remains in effect for parts of the northern Plains. Storms will form later this afternoon within the surface trough near the eastern borders of MT and WY, with locally severe gusts or marginal hail possible. Additional storms may move across eastern ND into northwest MN late tonight into early Saturday morning, as the SK/MB upper trough skirts the area. To the southwest, isolated storms that develop over northern parts of the Mogollon Rim may produce localized strong gusts later this afternoon as outflows push southwestward into the deeply mixed boundary layer. Precipitable water values up to 0.75" should be sufficient for outflow production with a general west/southwest motion. ..Jewell.. 07/12/2024 .PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 12 2024/ ...Northern Plains... Broad diffluent northwesterly mid-level flow is present today across the northern Plains states. Full sunshine over the region will result in hot surface temperatures and inverted-v thermodynamic profiles from eastern MT/WY into the western Dakotas. Most morning CAM solutions suggest scattered high-based thunderstorm development by late afternoon, with activity spreading slowly eastward through the evening. Locally gusty/damaging winds are the main concern with these storms. Greater instability exists farther east in ND/SD/NE but will remain capped in most areas, unless congealing outflow from the west can intercept the higher theta-e air with some risk of wind/hail in the strongest cells. ...Southern MO/IL... Morning visible satellite imagery shows a remnant MCV over southern MO tracking slowly eastward. Ample low-level moisture and CAPE ahead of this system will likely result in scattered afternoon thunderstorms. Winds aloft are relatively weak, and convection should remain rather disorganized. However, the strongest storms could pose a risk of locally gusty winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN PLAINS...A SMALL PART OF THE LOWER OHIO VALLEY INTO NORTHERN ARKANSAS...AND A SMALL PART OF NORTHWEST ARIZONA... ...SUMMARY... Isolated severe wind and hail will be possible over the northern and central Great Plains from late afternoon into tonight, and this afternoon from the Ozarks to lower Ohio Valley. A Marginal Risk remains in effect for parts of the northern Plains. Storms will form later this afternoon within the surface trough near the eastern borders of MT and WY, with locally severe gusts or marginal hail possible. Additional storms may move across eastern ND into northwest MN late tonight into early Saturday morning, as the SK/MB upper trough skirts the area. To the southwest, isolated storms that develop over northern parts of the Mogollon Rim may produce localized strong gusts later this afternoon as outflows push southwestward into the deeply mixed boundary layer. Precipitable water values up to 0.75" should be sufficient for outflow production with a general west/southwest motion. ..Jewell.. 07/12/2024 .PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 12 2024/ ...Northern Plains... Broad diffluent northwesterly mid-level flow is present today across the northern Plains states. Full sunshine over the region will result in hot surface temperatures and inverted-v thermodynamic profiles from eastern MT/WY into the western Dakotas. Most morning CAM solutions suggest scattered high-based thunderstorm development by late afternoon, with activity spreading slowly eastward through the evening. Locally gusty/damaging winds are the main concern with these storms. Greater instability exists farther east in ND/SD/NE but will remain capped in most areas, unless congealing outflow from the west can intercept the higher theta-e air with some risk of wind/hail in the strongest cells. ...Southern MO/IL... Morning visible satellite imagery shows a remnant MCV over southern MO tracking slowly eastward. Ample low-level moisture and CAPE ahead of this system will likely result in scattered afternoon thunderstorms. Winds aloft are relatively weak, and convection should remain rather disorganized. However, the strongest storms could pose a risk of locally gusty winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Fri Jul 12 2024 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHERN PLAINS...A SMALL PART OF THE LOWER OHIO VALLEY INTO NORTHERN ARKANSAS...AND A SMALL PART OF NORTHWEST ARIZONA... ...SUMMARY... Isolated severe wind and hail will be possible over the northern and central Great Plains from late afternoon into tonight, and this afternoon from the Ozarks to lower Ohio Valley. A Marginal Risk remains in effect for parts of the northern Plains. Storms will form later this afternoon within the surface trough near the eastern borders of MT and WY, with locally severe gusts or marginal hail possible. Additional storms may move across eastern ND into northwest MN late tonight into early Saturday morning, as the SK/MB upper trough skirts the area. To the southwest, isolated storms that develop over northern parts of the Mogollon Rim may produce localized strong gusts later this afternoon as outflows push southwestward into the deeply mixed boundary layer. Precipitable water values up to 0.75" should be sufficient for outflow production with a general west/southwest motion. ..Jewell.. 07/12/2024 .PREV DISCUSSION... /ISSUED 1123 AM CDT Fri Jul 12 2024/ ...Northern Plains... Broad diffluent northwesterly mid-level flow is present today across the northern Plains states. Full sunshine over the region will result in hot surface temperatures and inverted-v thermodynamic profiles from eastern MT/WY into the western Dakotas. Most morning CAM solutions suggest scattered high-based thunderstorm development by late afternoon, with activity spreading slowly eastward through the evening. Locally gusty/damaging winds are the main concern with these storms. Greater instability exists farther east in ND/SD/NE but will remain capped in most areas, unless congealing outflow from the west can intercept the higher theta-e air with some risk of wind/hail in the strongest cells. ...Southern MO/IL... Morning visible satellite imagery shows a remnant MCV over southern MO tracking slowly eastward. Ample low-level moisture and CAPE ahead of this system will likely result in scattered afternoon thunderstorms. Winds aloft are relatively weak, and convection should remain rather disorganized. However, the strongest storms could pose a risk of locally gusty winds. Read more

No Mesoscale Discussions are in effect as of Fri Jul 12 20:05:02 UTC 2024.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Jul 12 2024 Valid 131200Z - 141200Z The current D2 Fire Weather largely remains on track with only minor adjustments needed to bring isolated dry thunder into portions of southern California. Sounding analysis supports potential for high-based storms, with little to no measurable precipitation within this region. Fuels within this region remain critically dry, further supported by recent fire activity. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0224 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue into the weekend across the western U.S. - especially across the Great Basin where isolated to scattered dry thunderstorms are expected to develop by mid-afternoon and persist into the overnight hours. Continued hot/dry conditions are expected across much of the West, with breezy winds likely across portions of the Pacific Northwest and northern Rockies on the northern periphery of a dominant upper ridge centered over the southern Great Basin. ...Dry Thunderstorms - Sierra Nevada and the Great Basin... A weak mid-level low is noted in early-morning water-vapor imagery off the CA coast to the west of a more dominant upper ridge. Concurrently, a plume of 0.5-0.9 inch PWAT values is slowly migrating northward from southern/central CA. This moisture will continue to spread north over the next 48 hours and will phase with the mid-level impulse as it moves north Saturday afternoon/overnight. The combination of increasing mid-level moisture atop very dry boundary-layer conditions - along with 20-25 knot mean storm motions - will support the potential for dry thunderstorms. Forecast guidance suggests thunderstorms will initially develop across the southern Sierra Nevada into the lower CO River Valley Saturday afternoon around peak heating, slowly spreading north during the evening and overnight hours. Ensemble guidance currently depicts low (30% or lower) probability for wetting rainfall, and recent fuel guidance indicates that lightning-ignition efficiency is fairly high (15-20%) along the Sierra Nevada and into central NV/southern OR/ID. Consequently, dry lightning concerns are likely, and an upgrade to Scattered Dry Thunderstorms may be warranted if a corridor of higher thunderstorm potential becomes apparent in high-res guidance. ...Pacific Northwest/northwest Nevada and ID/MT... Hot/dry conditions are expected to continue across the Pacific Northwest with another day of RH values in the single digits to low teens. A belt of strong mid-level flow should reside across the Cascades/northern Sierra Nevada into the northern Rockies, which will maintain lee troughing across eastern OR/WA and across the northern High Plains. A combination of modest gradient winds, downslope wind enhancement, and deep boundary-layer mixing should yield areas of 15-20 mph winds coincident with very dry conditions. Elevated fire weather conditions appear likely with localized critical conditions possible. ...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 0258 PM CDT Fri Jul 12 2024 Valid 131200Z - 141200Z The current D2 Fire Weather largely remains on track with only minor adjustments needed to bring isolated dry thunder into portions of southern California. Sounding analysis supports potential for high-based storms, with little to no measurable precipitation within this region. Fuels within this region remain critically dry, further supported by recent fire activity. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0224 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue into the weekend across the western U.S. - especially across the Great Basin where isolated to scattered dry thunderstorms are expected to develop by mid-afternoon and persist into the overnight hours. Continued hot/dry conditions are expected across much of the West, with breezy winds likely across portions of the Pacific Northwest and northern Rockies on the northern periphery of a dominant upper ridge centered over the southern Great Basin. ...Dry Thunderstorms - Sierra Nevada and the Great Basin... A weak mid-level low is noted in early-morning water-vapor imagery off the CA coast to the west of a more dominant upper ridge. Concurrently, a plume of 0.5-0.9 inch PWAT values is slowly migrating northward from southern/central CA. This moisture will continue to spread north over the next 48 hours and will phase with the mid-level impulse as it moves north Saturday afternoon/overnight. The combination of increasing mid-level moisture atop very dry boundary-layer conditions - along with 20-25 knot mean storm motions - will support the potential for dry thunderstorms. Forecast guidance suggests thunderstorms will initially develop across the southern Sierra Nevada into the lower CO River Valley Saturday afternoon around peak heating, slowly spreading north during the evening and overnight hours. Ensemble guidance currently depicts low (30% or lower) probability for wetting rainfall, and recent fuel guidance indicates that lightning-ignition efficiency is fairly high (15-20%) along the Sierra Nevada and into central NV/southern OR/ID. Consequently, dry lightning concerns are likely, and an upgrade to Scattered Dry Thunderstorms may be warranted if a corridor of higher thunderstorm potential becomes apparent in high-res guidance. ...Pacific Northwest/northwest Nevada and ID/MT... Hot/dry conditions are expected to continue across the Pacific Northwest with another day of RH values in the single digits to low teens. A belt of strong mid-level flow should reside across the Cascades/northern Sierra Nevada into the northern Rockies, which will maintain lee troughing across eastern OR/WA and across the northern High Plains. A combination of modest gradient winds, downslope wind enhancement, and deep boundary-layer mixing should yield areas of 15-20 mph winds coincident with very dry conditions. Elevated fire weather conditions appear likely with localized critical conditions possible. ...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 0258 PM CDT Fri Jul 12 2024 Valid 131200Z - 141200Z The current D2 Fire Weather largely remains on track with only minor adjustments needed to bring isolated dry thunder into portions of southern California. Sounding analysis supports potential for high-based storms, with little to no measurable precipitation within this region. Fuels within this region remain critically dry, further supported by recent fire activity. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0224 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue into the weekend across the western U.S. - especially across the Great Basin where isolated to scattered dry thunderstorms are expected to develop by mid-afternoon and persist into the overnight hours. Continued hot/dry conditions are expected across much of the West, with breezy winds likely across portions of the Pacific Northwest and northern Rockies on the northern periphery of a dominant upper ridge centered over the southern Great Basin. ...Dry Thunderstorms - Sierra Nevada and the Great Basin... A weak mid-level low is noted in early-morning water-vapor imagery off the CA coast to the west of a more dominant upper ridge. Concurrently, a plume of 0.5-0.9 inch PWAT values is slowly migrating northward from southern/central CA. This moisture will continue to spread north over the next 48 hours and will phase with the mid-level impulse as it moves north Saturday afternoon/overnight. The combination of increasing mid-level moisture atop very dry boundary-layer conditions - along with 20-25 knot mean storm motions - will support the potential for dry thunderstorms. Forecast guidance suggests thunderstorms will initially develop across the southern Sierra Nevada into the lower CO River Valley Saturday afternoon around peak heating, slowly spreading north during the evening and overnight hours. Ensemble guidance currently depicts low (30% or lower) probability for wetting rainfall, and recent fuel guidance indicates that lightning-ignition efficiency is fairly high (15-20%) along the Sierra Nevada and into central NV/southern OR/ID. Consequently, dry lightning concerns are likely, and an upgrade to Scattered Dry Thunderstorms may be warranted if a corridor of higher thunderstorm potential becomes apparent in high-res guidance. ...Pacific Northwest/northwest Nevada and ID/MT... Hot/dry conditions are expected to continue across the Pacific Northwest with another day of RH values in the single digits to low teens. A belt of strong mid-level flow should reside across the Cascades/northern Sierra Nevada into the northern Rockies, which will maintain lee troughing across eastern OR/WA and across the northern High Plains. A combination of modest gradient winds, downslope wind enhancement, and deep boundary-layer mixing should yield areas of 15-20 mph winds coincident with very dry conditions. Elevated fire weather conditions appear likely with localized critical conditions possible. ...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 0258 PM CDT Fri Jul 12 2024 Valid 131200Z - 141200Z The current D2 Fire Weather largely remains on track with only minor adjustments needed to bring isolated dry thunder into portions of southern California. Sounding analysis supports potential for high-based storms, with little to no measurable precipitation within this region. Fuels within this region remain critically dry, further supported by recent fire activity. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0224 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue into the weekend across the western U.S. - especially across the Great Basin where isolated to scattered dry thunderstorms are expected to develop by mid-afternoon and persist into the overnight hours. Continued hot/dry conditions are expected across much of the West, with breezy winds likely across portions of the Pacific Northwest and northern Rockies on the northern periphery of a dominant upper ridge centered over the southern Great Basin. ...Dry Thunderstorms - Sierra Nevada and the Great Basin... A weak mid-level low is noted in early-morning water-vapor imagery off the CA coast to the west of a more dominant upper ridge. Concurrently, a plume of 0.5-0.9 inch PWAT values is slowly migrating northward from southern/central CA. This moisture will continue to spread north over the next 48 hours and will phase with the mid-level impulse as it moves north Saturday afternoon/overnight. The combination of increasing mid-level moisture atop very dry boundary-layer conditions - along with 20-25 knot mean storm motions - will support the potential for dry thunderstorms. Forecast guidance suggests thunderstorms will initially develop across the southern Sierra Nevada into the lower CO River Valley Saturday afternoon around peak heating, slowly spreading north during the evening and overnight hours. Ensemble guidance currently depicts low (30% or lower) probability for wetting rainfall, and recent fuel guidance indicates that lightning-ignition efficiency is fairly high (15-20%) along the Sierra Nevada and into central NV/southern OR/ID. Consequently, dry lightning concerns are likely, and an upgrade to Scattered Dry Thunderstorms may be warranted if a corridor of higher thunderstorm potential becomes apparent in high-res guidance. ...Pacific Northwest/northwest Nevada and ID/MT... Hot/dry conditions are expected to continue across the Pacific Northwest with another day of RH values in the single digits to low teens. A belt of strong mid-level flow should reside across the Cascades/northern Sierra Nevada into the northern Rockies, which will maintain lee troughing across eastern OR/WA and across the northern High Plains. A combination of modest gradient winds, downslope wind enhancement, and deep boundary-layer mixing should yield areas of 15-20 mph winds coincident with very dry conditions. Elevated fire weather conditions appear likely with localized critical conditions possible. ...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 0258 PM CDT Fri Jul 12 2024 Valid 131200Z - 141200Z The current D2 Fire Weather largely remains on track with only minor adjustments needed to bring isolated dry thunder into portions of southern California. Sounding analysis supports potential for high-based storms, with little to no measurable precipitation within this region. Fuels within this region remain critically dry, further supported by recent fire activity. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0224 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue into the weekend across the western U.S. - especially across the Great Basin where isolated to scattered dry thunderstorms are expected to develop by mid-afternoon and persist into the overnight hours. Continued hot/dry conditions are expected across much of the West, with breezy winds likely across portions of the Pacific Northwest and northern Rockies on the northern periphery of a dominant upper ridge centered over the southern Great Basin. ...Dry Thunderstorms - Sierra Nevada and the Great Basin... A weak mid-level low is noted in early-morning water-vapor imagery off the CA coast to the west of a more dominant upper ridge. Concurrently, a plume of 0.5-0.9 inch PWAT values is slowly migrating northward from southern/central CA. This moisture will continue to spread north over the next 48 hours and will phase with the mid-level impulse as it moves north Saturday afternoon/overnight. The combination of increasing mid-level moisture atop very dry boundary-layer conditions - along with 20-25 knot mean storm motions - will support the potential for dry thunderstorms. Forecast guidance suggests thunderstorms will initially develop across the southern Sierra Nevada into the lower CO River Valley Saturday afternoon around peak heating, slowly spreading north during the evening and overnight hours. Ensemble guidance currently depicts low (30% or lower) probability for wetting rainfall, and recent fuel guidance indicates that lightning-ignition efficiency is fairly high (15-20%) along the Sierra Nevada and into central NV/southern OR/ID. Consequently, dry lightning concerns are likely, and an upgrade to Scattered Dry Thunderstorms may be warranted if a corridor of higher thunderstorm potential becomes apparent in high-res guidance. ...Pacific Northwest/northwest Nevada and ID/MT... Hot/dry conditions are expected to continue across the Pacific Northwest with another day of RH values in the single digits to low teens. A belt of strong mid-level flow should reside across the Cascades/northern Sierra Nevada into the northern Rockies, which will maintain lee troughing across eastern OR/WA and across the northern High Plains. A combination of modest gradient winds, downslope wind enhancement, and deep boundary-layer mixing should yield areas of 15-20 mph winds coincident with very dry conditions. Elevated fire weather conditions appear likely with localized critical conditions possible. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...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 1242 PM CDT Fri Jul 12 2024 Valid 121700Z - 131200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON...FAR NORTHWESTERN NEVADA... ...CRITICAL FIRE WEATHER AREA FOR EAST-CENTRAL IDAHO... Elevated to Critical fire weather is expected across portions of the Great Basin region into the Pacific Northwest, with windy/dry conditions as well as several areas of isolated dry thunderstorms. ...East-Central Idaho (Snake River Plain)... A Critical delineation was added into portions of east-central Idaho within the Snake River Plain. Within this region, afternoon relative humidity reductions to 10 percent will overlap sustained west-southwest winds at 15-20 mph amid critically dry fuels. Deterministic guidance is in agreement with this, as well as HREF ensemble guidance which has a 70-80 percent probability of Critical conditions being met for several hours in the late afternoon/early evening. The forecast for Critical conditions across southeastern Oregon into far northwestern Nevada remains unchanged. Areas of isolated dry thunderstorm activity across the Sierra Nevada and Arizona/Utah Strip also remain unchanged with this outlook. See previous discussion for more information. ..Thornton.. 07/12/2024 .PREV DISCUSSION... /ISSUED 0220 AM CDT Fri Jul 12 2024/ ...Synopsis... Fire weather concerns will continue today across portions of the greater Great Basin region. Another day of very hot/dry conditions is expected today as afternoon highs across much of the West climb above 100 F. As of 05 UTC, single-digit RH values were noted across much of the region with little, if any, improvement in surface relative humidity anticipated over the next 24 hours. Despite the hot/dry conditions, an upper ridge centered over southern NV will continue to promote relatively benign winds for most locations, with the exception of the northern Great Basin where gradient winds on the periphery of the ridge will be slightly stronger. Isolated dry thunderstorms will also pose a fire weather concern across parts of the lower CO River Valley and along the Sierra Nevada. ...Southeast OR into southern WY... A low-amplitude mid-level impulse is noted in early-morning water-vapor imagery approaching the Pacific Northwest. Stronger mid-level flow associated with this feature should overspread the Cascades and northern Rockies through the day, leading to modest surface pressure falls across eastern OR/WA into western ID as well as along the northern High Plains. Low-level winds should strengthen to between 15-20 mph within a belt stretching from southern OR into southern ID and southern WY. Active fire behavior over the past 24 hours across east-central OR (even the absence of substantial winds) suggests that fuels are very receptive to fire spread, so the combination of very dry and breezy conditions will support elevated to critical fire weather. A Critical risk area has been introduced for portions of southeast OR into adjacent areas of northwest NV and far northeast CA where ensemble guidance shows a reasonably strong signal (70% probability in latest HREF and NBM guidance) for sustained winds between 20-25 mph and the potential for gusts up to 35 mph. ...Lower CO River Valley into the Sierra Nevada... 00 UTC soundings sampled a plume of 0.5-0.9 inch precipitable water values across the Four Corners region into southern CA. Recent GOES imagery shows this plume gradually migrating west/northwestward along the southern/southwestern side of the upper ridge. Steep mid-level lapse rates across the region coupled with deep boundary-layer mixing should support meager, but sufficient, buoyancy for convection. Thunderstorm coverage should be fairly isolated and tied to terrain features, as orographic ascent drives thunderstorm development around peak heating. However, dry lightning appears probable with any convection that can develop given the very dry low-level conditions, and should pose a fire weather concern given antecedent dry fuels. ...Please see www.spc.noaa.gov/fire for graphic product... Read more