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SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0347 PM CDT Sun Sep 08 2024 Valid 101200Z - 161200Z A broad upper ridge will remain across the middle portions of the U.S. through the early parts of this week. Another strong upper trough will begin to approach the Northwest. By midweek, the trough will impact the Great Basin before lifting northeast into the northern Plains by the weekend. Another amplified trough may impact the western U.S. by next weekend, but confidence in the upper air pattern this far in advance is still low. ...Great Basin... Fire weather concerns will increase on Tuesday with the approach of the strong trough. An initially weak surface pattern will lead to less widespread winds of 15-20 mph (locally higher). Areas of northwest and southern Nevada and nearby vicinity appear most likely to observe several hours of elevated conditions. Greater fire weather concerns will develop on Wednesday as the trough moves into the western Basin by late afternoon. Widespread 15-25 mph winds appear probable. With the mid-level jet nosing into northern Sierra by late afternoon, some intense wind gusts could occur in the lee of the terrain of northwest Nevada for at least a brief period. Another corridor of strong wind is expected from southern Nevada into western Utah just ahead of the front. ...Northern/Central Plains... As the trough approaches, deepening surface cyclones on Wednesday and Thursday will drive strong surface winds across parts of the Plains. With preceding days of dry weather and the upper ridge driving above average temperatures, fine fuels should continue to dry and available ERC data suggest some areas will again approach the 90th percentile. As winds shift to southerly, it will take time to advect moisture northward. Furthermore, the tropical system in the Gulf will likely slow moisture return as offshore flow develops along its western flank. That said, the drier solutions have been given more weight this forecast even though signals for critical fire weather are weaker in the ECMWF and available ensembles. The strongest winds over the broadest area will likely occur on Thursday. Some signal for convection in the surface trough on Wednesday is noted, but amounts should remain isolated and minimal. ...Columbia Gorge... There is potential for elevated to briefly critical fire weather to occur on Tuesday. Increasing mid-level winds will combine with a strong onshore pressure gradient to drive 15-20 mph winds through the Gorge along with RH potentially near 15%. The duration of these conditions may be brief enough that highlights will not be warranted. ..Wendt.. 09/08/2024 ...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 0347 PM CDT Sun Sep 08 2024 Valid 101200Z - 161200Z A broad upper ridge will remain across the middle portions of the U.S. through the early parts of this week. Another strong upper trough will begin to approach the Northwest. By midweek, the trough will impact the Great Basin before lifting northeast into the northern Plains by the weekend. Another amplified trough may impact the western U.S. by next weekend, but confidence in the upper air pattern this far in advance is still low. ...Great Basin... Fire weather concerns will increase on Tuesday with the approach of the strong trough. An initially weak surface pattern will lead to less widespread winds of 15-20 mph (locally higher). Areas of northwest and southern Nevada and nearby vicinity appear most likely to observe several hours of elevated conditions. Greater fire weather concerns will develop on Wednesday as the trough moves into the western Basin by late afternoon. Widespread 15-25 mph winds appear probable. With the mid-level jet nosing into northern Sierra by late afternoon, some intense wind gusts could occur in the lee of the terrain of northwest Nevada for at least a brief period. Another corridor of strong wind is expected from southern Nevada into western Utah just ahead of the front. ...Northern/Central Plains... As the trough approaches, deepening surface cyclones on Wednesday and Thursday will drive strong surface winds across parts of the Plains. With preceding days of dry weather and the upper ridge driving above average temperatures, fine fuels should continue to dry and available ERC data suggest some areas will again approach the 90th percentile. As winds shift to southerly, it will take time to advect moisture northward. Furthermore, the tropical system in the Gulf will likely slow moisture return as offshore flow develops along its western flank. That said, the drier solutions have been given more weight this forecast even though signals for critical fire weather are weaker in the ECMWF and available ensembles. The strongest winds over the broadest area will likely occur on Thursday. Some signal for convection in the surface trough on Wednesday is noted, but amounts should remain isolated and minimal. ...Columbia Gorge... There is potential for elevated to briefly critical fire weather to occur on Tuesday. Increasing mid-level winds will combine with a strong onshore pressure gradient to drive 15-20 mph winds through the Gorge along with RH potentially near 15%. The duration of these conditions may be brief enough that highlights will not be warranted. ..Wendt.. 09/08/2024 ...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 0242 PM CDT Sun Sep 08 2024 Valid 082000Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...20Z Update... The forecast remains on track, and no changes/additions were needed to the outlook with this update. In addition to the low-end/ localized convective concerns described below, a couple dry microbursts could accompany high-based thunderstorms developing over the higher terrain in portions of Southern CA this afternoon. While weak deep-layer flow/shear will limit thunderstorm organization/longevity here, a hot/deeply mixed boundary layer (temperatures around 100 F), and lower/middle 50s F dewpoints will still favor a few robust (albeit short-lived) storms capable of locally strong gusts. ..Weinman.. 09/08/2024 .PREV DISCUSSION... /ISSUED 1116 AM CDT Sun Sep 08 2024/ ...Synopsis and Discussion... Recent surface observations show a nearly stalled front over north FL. Daytime heating of a moist low-level airmass south of this boundary will likely encourage the development of scattered to numerous thunderstorms this afternoon over the northern and central FL Peninsula. While occasional strong/gusty winds may occur with any downdrafts, the presence of poor mid-level lapse rates should hinder updraft acceleration and overall convective intensity. Even with upper ridging remaining prominent over much of the West, high-based convection may develop this afternoon over the southern/central Rockies, and perhaps into the adjacent High Plains along/near a weak lee surface trough. Limited low-level moisture and generally weak effective bulk shear over these regions will likely preclude an organized severe threat, although strong winds may occur with any convection that can be sustained. Water vapor satellite imagery shows a mid-level shortwave trough over the Pacific Northwest this morning. This feature will move generally east-northeastward towards the northern Rockies through the period. Isolated thunderstorms may occur across interior portions of the Northwest this afternoon ahead of the shortwave trough. But, rather modest low-level moisture (surface dewpoints generally in the 30s/40s F) should hinder the development of any more than weak instability. Along with only modestly enhanced mid-level flow, the limited instability is expected to keep any severe wind threat with convective downdrafts across eastern WA/OR into ID and northern NV/UT quite sparse. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0154 PM CDT Sun Sep 08 2024 Valid 101200Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected to develop on Tuesday across the Gulf Coast region and from the Four Corners northward into the north-central U.S. No severe threat is expected across the U.S. Tuesday or Tuesday night. ...Synopsis... A broad mid-level trough will impinge on the northwestern U.S. as upper ridging prevails over much of the CONUS on Tuesday. Surface high pressure will promote cool and stable conditions from the Midwest to the East Coast, limiting thunderstorm potential. However, orographic lift over the higher terrain in the Interior West, as well as surface lee troughing in the central and northern Plains, will promote at least isolated thunderstorm development during the afternoon and early evening hours. Steep lapse rates will overspread the northern Plains and Upper MS Valley regions by afternoon, promoting at least moderate instability, though the lack of low-level moisture should limit severe potential. The heating of rich low-level moisture along the Gulf Coast will encourage scattered thunderstorm development. By Tuesday, a tropical storm is likely to develop to the southeast of the TX coastline (per latest NHC forecast). The probable track of this developing tropical storm suggests that the more organized convection should remain offshore through Tuesday, which should keep any severe threat to a minimum. ..Squitieri.. 09/08/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0154 PM CDT Sun Sep 08 2024 Valid 101200Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected to develop on Tuesday across the Gulf Coast region and from the Four Corners northward into the north-central U.S. No severe threat is expected across the U.S. Tuesday or Tuesday night. ...Synopsis... A broad mid-level trough will impinge on the northwestern U.S. as upper ridging prevails over much of the CONUS on Tuesday. Surface high pressure will promote cool and stable conditions from the Midwest to the East Coast, limiting thunderstorm potential. However, orographic lift over the higher terrain in the Interior West, as well as surface lee troughing in the central and northern Plains, will promote at least isolated thunderstorm development during the afternoon and early evening hours. Steep lapse rates will overspread the northern Plains and Upper MS Valley regions by afternoon, promoting at least moderate instability, though the lack of low-level moisture should limit severe potential. The heating of rich low-level moisture along the Gulf Coast will encourage scattered thunderstorm development. By Tuesday, a tropical storm is likely to develop to the southeast of the TX coastline (per latest NHC forecast). The probable track of this developing tropical storm suggests that the more organized convection should remain offshore through Tuesday, which should keep any severe threat to a minimum. ..Squitieri.. 09/08/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 PM CDT Sun Sep 08 2024 Valid 091200Z - 101200Z No changes are needed to the ongoing forecast. ..Wendt.. 09/08/2024 .PREV DISCUSSION... /ISSUED 0210 AM CDT Sun Sep 08 2024/ ...Synopsis... A prominent shortwave, embedded within broader troughing over the Pacific Northwest, is forecast to move quickly eastward over parts of the Northern Rockies Monday. At the same time, ridging over the West should continue to weaken as a belt of stronger southwesterly flow aloft develops from the northern Great Basin and into the northern Rockies. Increasing surface winds, and warm/dry conditions will support the potential for elevated fire-weather conditions. ...Northwest and Great Basin... As troughing settles over the West Coast, the mid-level flow will continue to strengthen across the Sierras and northern Great Basin. Surface winds of 15-25 mph appear likely as momentum from aloft mixes down to the surface. Downsloping and continued warm temperatures should keep the air mass quite dry with RH minimums of 15-20% likely. Several hours of widespread elevated to near-critical fire-weather conditions are likely from northern CA/NV into parts of southern ID and western WY. A few hours of elevated to near-critical conditions are possible in the lee of the Cascades as winds increase ahead of a cold front moving onshore Monday. RH may be on the marginal side, particularly with northward extent, as a cooler Pacific air mass move in. However, downslope winds of 15-25 mph and recent active fire behavior suggest some fire weather concerns will be possible. ...Northern Rockies... As the shortwave trough approaches the Rockies, westerly flow aloft should quickly increase. Downslope trajectories and intensifying lee troughing will strengthen surface winds to 15-20 MPH across parts of MT and WY. With hot temperatures and little recent rainfall persisting, afternoon RH values should remain quite low, generally below 20-25%. With increasing winds, receptive fuels, and persistent dry conditions, periods of elevated fire-weather conditions are likely over parts of the northern Rockies. ...Dry Thunder... Across parts of the eastern Great Basin and central Rockies, lingering monsoon moisture will likely support isolated to scattered thunderstorms Monday afternoon. A mixed mode of wet and dry storms is expected with PWATs of 0.7-1 inch, and increasing mid-level flow supporting faster storm speeds. While there is some potential for drier strikes, fuels across much of the area are less receptive and storms should generally cluster with time. This suggests any dry lightning potential will be limited. ...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 0150 PM CDT Sun Sep 08 2024 Valid 091200Z - 101200Z No changes are needed to the ongoing forecast. ..Wendt.. 09/08/2024 .PREV DISCUSSION... /ISSUED 0210 AM CDT Sun Sep 08 2024/ ...Synopsis... A prominent shortwave, embedded within broader troughing over the Pacific Northwest, is forecast to move quickly eastward over parts of the Northern Rockies Monday. At the same time, ridging over the West should continue to weaken as a belt of stronger southwesterly flow aloft develops from the northern Great Basin and into the northern Rockies. Increasing surface winds, and warm/dry conditions will support the potential for elevated fire-weather conditions. ...Northwest and Great Basin... As troughing settles over the West Coast, the mid-level flow will continue to strengthen across the Sierras and northern Great Basin. Surface winds of 15-25 mph appear likely as momentum from aloft mixes down to the surface. Downsloping and continued warm temperatures should keep the air mass quite dry with RH minimums of 15-20% likely. Several hours of widespread elevated to near-critical fire-weather conditions are likely from northern CA/NV into parts of southern ID and western WY. A few hours of elevated to near-critical conditions are possible in the lee of the Cascades as winds increase ahead of a cold front moving onshore Monday. RH may be on the marginal side, particularly with northward extent, as a cooler Pacific air mass move in. However, downslope winds of 15-25 mph and recent active fire behavior suggest some fire weather concerns will be possible. ...Northern Rockies... As the shortwave trough approaches the Rockies, westerly flow aloft should quickly increase. Downslope trajectories and intensifying lee troughing will strengthen surface winds to 15-20 MPH across parts of MT and WY. With hot temperatures and little recent rainfall persisting, afternoon RH values should remain quite low, generally below 20-25%. With increasing winds, receptive fuels, and persistent dry conditions, periods of elevated fire-weather conditions are likely over parts of the northern Rockies. ...Dry Thunder... Across parts of the eastern Great Basin and central Rockies, lingering monsoon moisture will likely support isolated to scattered thunderstorms Monday afternoon. A mixed mode of wet and dry storms is expected with PWATs of 0.7-1 inch, and increasing mid-level flow supporting faster storm speeds. While there is some potential for drier strikes, fuels across much of the area are less receptive and storms should generally cluster with time. This suggests any dry lightning potential will be limited. ...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 1139 AM CDT Sun Sep 08 2024 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF WESTERN INTO CENTRAL NEW YORK... ...SUMMARY... Thunderstorms will be possible on Monday in parts of the lower Great Lakes, along the Gulf Coast, and from the Four Corners northward into the northern Plains. Some storms may produce damaging wind gusts over western into central New York. ...Synopsis... A pronounced mid-level trough will eject into the Atlantic while weaker mid-level troughs, embedded in mainly zonal flow, traverse the Pacific Northwest and Northern Plains tomorrow (Monday). Surface high pressure will dominate the Midwest to Atlantic Seaboard while surface troughing becomes established over the central and northern Plains. An embedded mid-level impulse will pivot around the backside of the East Coast trough and provide adequate lift for at least scattered thunderstorms over NY and immediate surrounding areas. Meanwhile, strong surface heating and orographic lift will encourage isolated to scattered thunderstorm development over the Great Basin into the Four Corners region, with scattered thunderstorm development also possible over the Northern Plains with the passage of a mid-level trough. Finally, scattered thunderstorms may also develop by afternoon peak heating amid a moist boundary layer along the Gulf Coast into FL. ...Portions of New York... A 500 mb speed max will rotate around the backside of the East Coast trough by afternoon, when boundary-layer heating will support the steepening of low-level lapse rates to about 7.5-8 C/km, resulting in over 500 J/kg MLCAPE over central NY. While buoyancy will be weak overall, the 500 mb speed max overspreading the region will result in elongated mid/upper-level hodographs. As such, highly sheared and low-topped multicell storms are expected to develop during the afternoon. Some of the stronger storms may produce potentially damaging wind gusts, necessitating the introduction of Category 1/Marginal risk probabilities. ..Squitieri.. 09/08/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1116 AM CDT Sun Sep 08 2024 Valid 081630Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Synopsis and Discussion... Recent surface observations show a nearly stalled front over north FL. Daytime heating of a moist low-level airmass south of this boundary will likely encourage the development of scattered to numerous thunderstorms this afternoon over the northern and central FL Peninsula. While occasional strong/gusty winds may occur with any downdrafts, the presence of poor mid-level lapse rates should hinder updraft acceleration and overall convective intensity. Even with upper ridging remaining prominent over much of the West, high-based convection may develop this afternoon over the southern/central Rockies, and perhaps into the adjacent High Plains along/near a weak lee surface trough. Limited low-level moisture and generally weak effective bulk shear over these regions will likely preclude an organized severe threat, although strong winds may occur with any convection that can be sustained. Water vapor satellite imagery shows a mid-level shortwave trough over the Pacific Northwest this morning. This feature will move generally east-northeastward towards the northern Rockies through the period. Isolated thunderstorms may occur across interior portions of the Northwest this afternoon ahead of the shortwave trough. But, rather modest low-level moisture (surface dewpoints generally in the 30s/40s F) should hinder the development of any more than weak instability. Along with only modestly enhanced mid-level flow, the limited instability is expected to keep any severe wind threat with convective downdrafts across eastern WA/OR into ID and northern NV/UT quite sparse. ..Gleason/Halbert.. 09/08/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1110 AM CDT Sun Sep 08 2024 Valid 081700Z - 091200Z No changes are needed to the ongoing forecast. ..Wendt.. 09/08/2024 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Sep 08 2024/ ...Synopsis... Broad troughing over the Pacific Northwest is forecast to intensify as a shortwave perturbation moves onshore across parts of WA and OR today. As the shortwave trough intensifies, flow aloft should also increase as it overspreads the Northwest and Great Basin. Showers and thunderstorms, along with gusty, winds are likely across much of the West, with elevated fire-weather potential. ...Dry Thunder... Beneath the cold core of the upper trough moving inland, a thunderstorm may be ongoing through the morning hours across portions of the Pacific Northwest. Greater storm coverage is expected to develop through the day, as daytime heating and lift from the upper trough interact with deepening mid-level moisture. Model soundings show weak buoyancy atop warm and dry low levels and storm motions greater than 20 kt. With poor precipitation efficiency expected, isolated to widely scattered dry thunderstorms appear likely over receptive fuels. Confidence in dry thunderstorm coverage is greatest across portions of the northern and central Cascades, into eastern ID and far southwestern MT. Scattered thunderstorms are also possible farther south across the southern Great Basin and southern CA. Displaced from the stronger flow aloft, and with access to more robust monsoon moisture, a wetter storm mode is expected. A few drier strikes are still possible outside of the wetter cores within receptive fuels, but the coverage of drier storms appears limited. ...Northern Great Basin and the Cascades... As the trough moves inland, a belt of stronger mid-level flow is expected to intensify over parts of the northern Great Basin and the southern Cascades. The stronger flow aloft will support an increase in surface winds to 15-25 mph. Residual warm temperatures beneath the weakening ridge and the increase in downslope winds will favor drier low levels, with RH minimums below 15% likely. Widespread elevated to near-critical fire-weather conditions are possible across the northern Sierra and Great Basin, where the dry and breezy conditions will overlap with areas of dry fuels. Farther north in the lee of the Cascades, gusty downslope and gap winds may also support brief elevated fire-weather potential as stronger flow aloft develops. However, some humidity recovery will eventually occur as marine influence will increase with time, potentially limiting the coverage and duration of fire-weather concerns. ...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 1110 AM CDT Sun Sep 08 2024 Valid 081700Z - 091200Z No changes are needed to the ongoing forecast. ..Wendt.. 09/08/2024 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Sep 08 2024/ ...Synopsis... Broad troughing over the Pacific Northwest is forecast to intensify as a shortwave perturbation moves onshore across parts of WA and OR today. As the shortwave trough intensifies, flow aloft should also increase as it overspreads the Northwest and Great Basin. Showers and thunderstorms, along with gusty, winds are likely across much of the West, with elevated fire-weather potential. ...Dry Thunder... Beneath the cold core of the upper trough moving inland, a thunderstorm may be ongoing through the morning hours across portions of the Pacific Northwest. Greater storm coverage is expected to develop through the day, as daytime heating and lift from the upper trough interact with deepening mid-level moisture. Model soundings show weak buoyancy atop warm and dry low levels and storm motions greater than 20 kt. With poor precipitation efficiency expected, isolated to widely scattered dry thunderstorms appear likely over receptive fuels. Confidence in dry thunderstorm coverage is greatest across portions of the northern and central Cascades, into eastern ID and far southwestern MT. Scattered thunderstorms are also possible farther south across the southern Great Basin and southern CA. Displaced from the stronger flow aloft, and with access to more robust monsoon moisture, a wetter storm mode is expected. A few drier strikes are still possible outside of the wetter cores within receptive fuels, but the coverage of drier storms appears limited. ...Northern Great Basin and the Cascades... As the trough moves inland, a belt of stronger mid-level flow is expected to intensify over parts of the northern Great Basin and the southern Cascades. The stronger flow aloft will support an increase in surface winds to 15-25 mph. Residual warm temperatures beneath the weakening ridge and the increase in downslope winds will favor drier low levels, with RH minimums below 15% likely. Widespread elevated to near-critical fire-weather conditions are possible across the northern Sierra and Great Basin, where the dry and breezy conditions will overlap with areas of dry fuels. Farther north in the lee of the Cascades, gusty downslope and gap winds may also support brief elevated fire-weather potential as stronger flow aloft develops. However, some humidity recovery will eventually occur as marine influence will increase with time, potentially limiting the coverage and duration of fire-weather concerns. ...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 0724 AM CDT Sun Sep 08 2024 Valid 081300Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Though a few strong thunderstorm gusts may be noted in the interior Northwest and central High Plains, severe potential appears too low and disorganized for an outlook area. ...Synopsis/Discussion... In mid/upper levels, the large-scale pattern will deamplify somewhat over the CONUS this period, but maintain a mean trough in the Great Lakes and eastern CONUS, and mean ridging over the Intermountain West and Southwestern deserts. A shortwave trough -- evident in moisture-channel imagery over the interior of OR/WA into far northern CA -- is forecast to continue weakening as it moves northeastward, crossing the northern Rockies between 06-12Z. Still, associated cooling aloft and midlevel moisture, over pockets of marginally favorable low-level moisture and diurnal surface heating, will contribute to general thunderstorm potential in parts of the interior Northwest and Intermountain West. A few of these high- based cells may produce strong gusts, but severe potential appears to be limited by lack of greater moisture/buoyancy. Farther east over the central Rockies and adjoining High Plains, isolated to widely scattered thunderstorms are possible this afternoon into evening. Activity should be related to diabatic heating of elevated terrain, along with lift near a surface lee trough, and a corridor of meager but sufficient low-level moisture. Beneath strongly difluent but weak west to northwest flow in mid/ upper levels, bulk shear should be modest, despite considerable veering with height. Here too, a few cells may produce strong gusts through a well-mixed subcloud layer, and a severe gust cannot be ruled out. However, severe potential appears too isolated, poorly focused and conditional for a categorical risk area. Elsewhere, isolated to scattered thunderstorms will be possible in a very moist air mass (but with poor lapse rates) from parts of the Gulf Coast States across FL and the southern Atlantic Coast. ..Edwards/Kerr.. 09/08/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Sep 08 2024 Valid 111200Z - 161200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to move across the north-central U.S. on Wednesday, as a trough develops in the western U.S. An upper-level low is forecast to move across the northwestern states from Wednesday to Friday. Ahead of the trough, thunderstorms will be possible each day from the Intermountain west eastward into the central and northern Plains. At this time, the potential for severe may be limited by instability, which is generally forecast to remain weak across most of the western and central U.S. In the Gulf Coast region, some model forecasts have a tropical system becoming organized in the northern Gulf from Wednesday to Friday. If this system materializes and can move onshore, the day with the greatest potential to impact the central Gulf Coast would be Thursday. A tornado threat could materialize as the system moves inland, depending upon its overall strength. ...Saturday/Day 7 and Sunday/Day 8... A shortwave trough is forecast to move eastward across the north-central U.S. on Saturday, as an upper-level low moves across the Ohio Valley and into the Great Lakes from Saturday into Sunday. Although the potential for severe storms over the weekend appears to be low at this time, substantial uncertainty exists at this extended range. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Sun Sep 08 2024 Valid 111200Z - 161200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... An upper-level ridge is forecast to move across the north-central U.S. on Wednesday, as a trough develops in the western U.S. An upper-level low is forecast to move across the northwestern states from Wednesday to Friday. Ahead of the trough, thunderstorms will be possible each day from the Intermountain west eastward into the central and northern Plains. At this time, the potential for severe may be limited by instability, which is generally forecast to remain weak across most of the western and central U.S. In the Gulf Coast region, some model forecasts have a tropical system becoming organized in the northern Gulf from Wednesday to Friday. If this system materializes and can move onshore, the day with the greatest potential to impact the central Gulf Coast would be Thursday. A tornado threat could materialize as the system moves inland, depending upon its overall strength. ...Saturday/Day 7 and Sunday/Day 8... A shortwave trough is forecast to move eastward across the north-central U.S. on Saturday, as an upper-level low moves across the Ohio Valley and into the Great Lakes from Saturday into Sunday. Although the potential for severe storms over the weekend appears to be low at this time, substantial uncertainty exists at this extended range. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CDT Sun Sep 08 2024 Valid 101200Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected to develop on Tuesday across the Gulf Coast region and from the Four Corners northward into the north-central U.S. No severe threat is expected across the U.S. Tuesday or Tuesday night. ...DISCUSSION... A shortwave ridge is forecast to move eastward across the Great Lakes and Ohio Valley on Tuesday, a shortwave trough moves across the northern Plains. At the surface, a cold front is forecast to advance southeastward across the central and northern Plains. Thunderstorm development will be possible along and near parts of the front, and further west in the higher terrain of the central and northern Rockies. Additional thunderstorms will be possible in the Gulf Coast region along the northern edge of a moist airmass. No severe threat is expected across the U.S. on Tuesday and Tuesday night. ..Broyles.. 09/08/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CDT Sun Sep 08 2024 Valid 101200Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are expected to develop on Tuesday across the Gulf Coast region and from the Four Corners northward into the north-central U.S. No severe threat is expected across the U.S. Tuesday or Tuesday night. ...DISCUSSION... A shortwave ridge is forecast to move eastward across the Great Lakes and Ohio Valley on Tuesday, a shortwave trough moves across the northern Plains. At the surface, a cold front is forecast to advance southeastward across the central and northern Plains. Thunderstorm development will be possible along and near parts of the front, and further west in the higher terrain of the central and northern Rockies. Additional thunderstorms will be possible in the Gulf Coast region along the northern edge of a moist airmass. No severe threat is expected across the U.S. on Tuesday and Tuesday night. ..Broyles.. 09/08/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0210 AM CDT Sun Sep 08 2024 Valid 091200Z - 101200Z ...Synopsis... A prominent shortwave, embedded within broader troughing over the Pacific Northwest, is forecast to move quickly eastward over parts of the Northern Rockies Monday. At the same time, ridging over the West should continue to weaken as a belt of stronger southwesterly flow aloft develops from the northern Great Basin and into the northern Rockies. Increasing surface winds, and warm/dry conditions will support the potential for elevated fire-weather conditions. ...Northwest and Great Basin... As troughing settles over the West Coast, the mid-level flow will continue to strengthen across the Sierras and northern Great Basin. Surface winds of 15-25 mph appear likely as momentum from aloft mixes down to the surface. Downsloping and continued warm temperatures should keep the air mass quite dry with RH minimums of 15-20% likely. Several hours of widespread elevated to near-critical fire-weather conditions are likely from northern CA/NV into parts of southern ID and western WY. A few hours of elevated to near-critical conditions are possible in the lee of the Cascades as winds increase ahead of a cold front moving onshore Monday. RH may be on the marginal side, particularly with northward extent, as a cooler Pacific air mass move in. However, downslope winds of 15-25 mph and recent active fire behavior suggest some fire weather concerns will be possible. ...Northern Rockies... As the shortwave trough approaches the Rockies, westerly flow aloft should quickly increase. Downslope trajectories and intensifying lee troughing will strengthen surface winds to 15-20 MPH across parts of MT and WY. With hot temperatures and little recent rainfall persisting, afternoon RH values should remain quite low, generally below 20-25%. With increasing winds, receptive fuels, and persistent dry conditions, periods of elevated fire-weather conditions are likely over parts of the northern Rockies. ...Dry Thunder... Across parts of the eastern Great Basin and central Rockies, lingering monsoon moisture will likely support isolated to scattered thunderstorms Monday afternoon. A mixed mode of wet and dry storms is expected with PWATs of 0.7-1 inch, and increasing mid-level flow supporting faster storm speeds. While there is some potential for drier strikes, fuels across much of the area are less receptive and storms should generally cluster with time. This suggests any dry lightning potential will be limited. ..Lyons.. 09/08/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Sun Sep 08 2024 Valid 081200Z - 091200Z ...Synopsis... Broad troughing over the Pacific Northwest is forecast to intensify as a shortwave perturbation moves onshore across parts of WA and OR today. As the shortwave trough intensifies, flow aloft should also increase as it overspreads the Northwest and Great Basin. Showers and thunderstorms, along with gusty, winds are likely across much of the West, with elevated fire-weather potential. ...Dry Thunder... Beneath the cold core of the upper trough moving inland, a thunderstorm may be ongoing through the morning hours across portions of the Pacific Northwest. Greater storm coverage is expected to develop through the day, as daytime heating and lift from the upper trough interact with deepening mid-level moisture. Model soundings show weak buoyancy atop warm and dry low levels and storm motions greater than 20 kt. With poor precipitation efficiency expected, isolated to widely scattered dry thunderstorms appear likely over receptive fuels. Confidence in dry thunderstorm coverage is greatest across portions of the northern and central Cascades, into eastern ID and far southwestern MT. Scattered thunderstorms are also possible farther south across the southern Great Basin and southern CA. Displaced from the stronger flow aloft, and with access to more robust monsoon moisture, a wetter storm mode is expected. A few drier strikes are still possible outside of the wetter cores within receptive fuels, but the coverage of drier storms appears limited. ...Northern Great Basin and the Cascades... As the trough moves inland, a belt of stronger mid-level flow is expected to intensify over parts of the northern Great Basin and the southern Cascades. The stronger flow aloft will support an increase in surface winds to 15-25 mph. Residual warm temperatures beneath the weakening ridge and the increase in downslope winds will favor drier low levels, with RH minimums below 15% likely. Widespread elevated to near-critical fire-weather conditions are possible across the northern Sierra and Great Basin, where the dry and breezy conditions will overlap with areas of dry fuels. Farther north in the lee of the Cascades, gusty downslope and gap winds may also support brief elevated fire-weather potential as stronger flow aloft develops. However, some humidity recovery will eventually occur as marine influence will increase with time, potentially limiting the coverage and duration of fire-weather concerns. ..Lyons.. 09/08/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Sun Sep 08 2024 Valid 091200Z - 101200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will be possible on Monday in parts of the lower Great Lakes, along the Gulf Coast, and from the Four Corners northward into the northern Plains. No severe weather is expected Monday or Monday night. ...DISCUSSION... An upper-level trough will move eastward through the Northeast on Monday. Isolated to scattered thunderstorms are expected to develop from near the trough westward into the lower Great Lakes, aided by strong large-scale ascent and cold air aloft. Thunderstorms will also be possible along parts of the Gulf Coast on the northern edge of a moist airmass. Additionally, scattered thunderstorms are expected to develop in the Four Corners, with more isolated storms forming over the north-central states. No severe weather is expected across the continental United States Monday or Monday night. ..Broyles.. 09/08/2024 Read more