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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Tue Sep 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER COASTAL AREAS OF LOUISIANA... ...SUMMARY... Marginal tornado potential may reach coastal areas of Louisiana during the late overnight/early morning hours. ...Synopsis... In mid/upper levels, a strong shortwave trough now over the eastern Gulf of Alaska is forecast to dig southeastward and develop a closed 500-mb cyclone tonight, with the low about 150 nm west of AST by 12Z tomorrow. Ahead of this progressive and intensifying perturbation, height falls and strengthening cyclonic flow will spread across the northwestern CONUS throughout the period, combining with modest low/ middle-level moisture to support thunderstorm potential in parts of the Northwest, in addition to the diurnal-cycle convection across the Four Corners region, central/northern Rockies and parts of MT. Downstream, mid/upper flow should be nearly zonal from the Rockies across the Great Lakes. An embedded shortwave trough was evident in moisture-channel imagery over the Dakotas. This feature is forecast to move eastward to MN by 00Z, then across the Upper Great Lakes to Lake Huron and adjoining parts of ON by 12Z. Farther south, a weak, cut-off, mid/upper-level low over north-central TX should drift erratically near its present location, while increasingly influencing the path of Tropical Storm Francine. The 11Z surface analysis showed a wavy, quasistationary frontal zone fro Atlantic waters offshore SC, across northern FL to near the Mississippi River mouth, then a warm front arching across Gulf waters just south of the LA and TX Coasts, and into western parts of the Francine circulation. This boundary should move little from about 90W eastward, but remain a warm front over the upper TX and LA coastal waters, diffusely shifting inland over southern LA through the period. ...LA Coast... T.S. Francine -- initially centered southeast of BRO -- is forecast by NHC to turn northeastward across the northwestern Gulf today and become a hurricane, then move ashore in Louisiana on day 2. Suitably rich low-level moisture already is in place over coastal LA, and scattered to numerous showers and thunderstorms should cover the outlook area throughout much of the period, even well northeast of Francine's center. However, supercell potential will await sufficiently strong wind fields reaching the coastline ahead of the cyclone to enlarge hodographs favorably -- likely during the last few hours of the period. Then, tornado potential will be a matter of having relatively distinct/discrete, outer-band convection that can survive long enough to mature into supercells before weakening again in more-stable inflow air -- either inland or in broader precip areas. Unconditional probabilities are kept at marginal levels for now, given the late timing of the favorable kinematic fields, the nocturnal min in overland instability, and convective/ structural uncertainties with Francine. ..Edwards/Kerr.. 09/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Tue Sep 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER COASTAL AREAS OF LOUISIANA... ...SUMMARY... Marginal tornado potential may reach coastal areas of Louisiana during the late overnight/early morning hours. ...Synopsis... In mid/upper levels, a strong shortwave trough now over the eastern Gulf of Alaska is forecast to dig southeastward and develop a closed 500-mb cyclone tonight, with the low about 150 nm west of AST by 12Z tomorrow. Ahead of this progressive and intensifying perturbation, height falls and strengthening cyclonic flow will spread across the northwestern CONUS throughout the period, combining with modest low/ middle-level moisture to support thunderstorm potential in parts of the Northwest, in addition to the diurnal-cycle convection across the Four Corners region, central/northern Rockies and parts of MT. Downstream, mid/upper flow should be nearly zonal from the Rockies across the Great Lakes. An embedded shortwave trough was evident in moisture-channel imagery over the Dakotas. This feature is forecast to move eastward to MN by 00Z, then across the Upper Great Lakes to Lake Huron and adjoining parts of ON by 12Z. Farther south, a weak, cut-off, mid/upper-level low over north-central TX should drift erratically near its present location, while increasingly influencing the path of Tropical Storm Francine. The 11Z surface analysis showed a wavy, quasistationary frontal zone fro Atlantic waters offshore SC, across northern FL to near the Mississippi River mouth, then a warm front arching across Gulf waters just south of the LA and TX Coasts, and into western parts of the Francine circulation. This boundary should move little from about 90W eastward, but remain a warm front over the upper TX and LA coastal waters, diffusely shifting inland over southern LA through the period. ...LA Coast... T.S. Francine -- initially centered southeast of BRO -- is forecast by NHC to turn northeastward across the northwestern Gulf today and become a hurricane, then move ashore in Louisiana on day 2. Suitably rich low-level moisture already is in place over coastal LA, and scattered to numerous showers and thunderstorms should cover the outlook area throughout much of the period, even well northeast of Francine's center. However, supercell potential will await sufficiently strong wind fields reaching the coastline ahead of the cyclone to enlarge hodographs favorably -- likely during the last few hours of the period. Then, tornado potential will be a matter of having relatively distinct/discrete, outer-band convection that can survive long enough to mature into supercells before weakening again in more-stable inflow air -- either inland or in broader precip areas. Unconditional probabilities are kept at marginal levels for now, given the late timing of the favorable kinematic fields, the nocturnal min in overland instability, and convective/ structural uncertainties with Francine. ..Edwards/Kerr.. 09/10/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Tue Sep 10 2024 Valid 101300Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER COASTAL AREAS OF LOUISIANA... ...SUMMARY... Marginal tornado potential may reach coastal areas of Louisiana during the late overnight/early morning hours. ...Synopsis... In mid/upper levels, a strong shortwave trough now over the eastern Gulf of Alaska is forecast to dig southeastward and develop a closed 500-mb cyclone tonight, with the low about 150 nm west of AST by 12Z tomorrow. Ahead of this progressive and intensifying perturbation, height falls and strengthening cyclonic flow will spread across the northwestern CONUS throughout the period, combining with modest low/ middle-level moisture to support thunderstorm potential in parts of the Northwest, in addition to the diurnal-cycle convection across the Four Corners region, central/northern Rockies and parts of MT. Downstream, mid/upper flow should be nearly zonal from the Rockies across the Great Lakes. An embedded shortwave trough was evident in moisture-channel imagery over the Dakotas. This feature is forecast to move eastward to MN by 00Z, then across the Upper Great Lakes to Lake Huron and adjoining parts of ON by 12Z. Farther south, a weak, cut-off, mid/upper-level low over north-central TX should drift erratically near its present location, while increasingly influencing the path of Tropical Storm Francine. The 11Z surface analysis showed a wavy, quasistationary frontal zone fro Atlantic waters offshore SC, across northern FL to near the Mississippi River mouth, then a warm front arching across Gulf waters just south of the LA and TX Coasts, and into western parts of the Francine circulation. This boundary should move little from about 90W eastward, but remain a warm front over the upper TX and LA coastal waters, diffusely shifting inland over southern LA through the period. ...LA Coast... T.S. Francine -- initially centered southeast of BRO -- is forecast by NHC to turn northeastward across the northwestern Gulf today and become a hurricane, then move ashore in Louisiana on day 2. Suitably rich low-level moisture already is in place over coastal LA, and scattered to numerous showers and thunderstorms should cover the outlook area throughout much of the period, even well northeast of Francine's center. However, supercell potential will await sufficiently strong wind fields reaching the coastline ahead of the cyclone to enlarge hodographs favorably -- likely during the last few hours of the period. Then, tornado potential will be a matter of having relatively distinct/discrete, outer-band convection that can survive long enough to mature into supercells before weakening again in more-stable inflow air -- either inland or in broader precip areas. Unconditional probabilities are kept at marginal levels for now, given the late timing of the favorable kinematic fields, the nocturnal min in overland instability, and convective/ structural uncertainties with Francine. ..Edwards/Kerr.. 09/10/2024 Read more

000
ABPZ20 KNHC 101112
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Tue Sep 10 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Offshore of Southwestern Mexico:
An area of low pressure is forecast to form during the next day or
two, just to the south of the coast of southwestern Mexico.
Environmental conditions are forecast to be conducive for some
gradual development of this system, and a tropical depression
could form during the latter part of the week while it moves
generally north-northwestward, near the coast of southwestern
Mexico.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...medium...60 percent.

$$
Forecaster Beven

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Tue Sep 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential appears low through the period. Primary concern for D4/Friday is any lingering tornado threat associated with the remnants of TC Francine. It is forecast by NHC to drift into the Mid-South/MS Valley to Lower OH Valley vicinity. Latest guidance indicates further weakening of low-level wind fields on Friday, likely becoming inadequate to sustain a synoptically evident TC tornado threat. Beyond this time frame, a quiescent pattern for severe is expected this weekend into early next week. Towards mid-week, majority of ensemble guidance suggests potential large-scale amplification of an upper trough into the West. This may yield an increase of low-probability severe around D8 and beyond over parts of the Great Plains, where many preceding days of above-normal temps will occur. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Tue Sep 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential appears low through the period. Primary concern for D4/Friday is any lingering tornado threat associated with the remnants of TC Francine. It is forecast by NHC to drift into the Mid-South/MS Valley to Lower OH Valley vicinity. Latest guidance indicates further weakening of low-level wind fields on Friday, likely becoming inadequate to sustain a synoptically evident TC tornado threat. Beyond this time frame, a quiescent pattern for severe is expected this weekend into early next week. Towards mid-week, majority of ensemble guidance suggests potential large-scale amplification of an upper trough into the West. This may yield an increase of low-probability severe around D8 and beyond over parts of the Great Plains, where many preceding days of above-normal temps will occur. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Tue Sep 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential appears low through the period. Primary concern for D4/Friday is any lingering tornado threat associated with the remnants of TC Francine. It is forecast by NHC to drift into the Mid-South/MS Valley to Lower OH Valley vicinity. Latest guidance indicates further weakening of low-level wind fields on Friday, likely becoming inadequate to sustain a synoptically evident TC tornado threat. Beyond this time frame, a quiescent pattern for severe is expected this weekend into early next week. Towards mid-week, majority of ensemble guidance suggests potential large-scale amplification of an upper trough into the West. This may yield an increase of low-probability severe around D8 and beyond over parts of the Great Plains, where many preceding days of above-normal temps will occur. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Tue Sep 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential appears low through the period. Primary concern for D4/Friday is any lingering tornado threat associated with the remnants of TC Francine. It is forecast by NHC to drift into the Mid-South/MS Valley to Lower OH Valley vicinity. Latest guidance indicates further weakening of low-level wind fields on Friday, likely becoming inadequate to sustain a synoptically evident TC tornado threat. Beyond this time frame, a quiescent pattern for severe is expected this weekend into early next week. Towards mid-week, majority of ensemble guidance suggests potential large-scale amplification of an upper trough into the West. This may yield an increase of low-probability severe around D8 and beyond over parts of the Great Plains, where many preceding days of above-normal temps will occur. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Tue Sep 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential appears low through the period. Primary concern for D4/Friday is any lingering tornado threat associated with the remnants of TC Francine. It is forecast by NHC to drift into the Mid-South/MS Valley to Lower OH Valley vicinity. Latest guidance indicates further weakening of low-level wind fields on Friday, likely becoming inadequate to sustain a synoptically evident TC tornado threat. Beyond this time frame, a quiescent pattern for severe is expected this weekend into early next week. Towards mid-week, majority of ensemble guidance suggests potential large-scale amplification of an upper trough into the West. This may yield an increase of low-probability severe around D8 and beyond over parts of the Great Plains, where many preceding days of above-normal temps will occur. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Tue Sep 10 2024 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE DEEP SOUTH AND THE NORTHERN HIGH PLAINS... ...SUMMARY... A low-probability tornado threat may persist into Thursday across parts of the Deep South. Isolated large hail and severe gusts will be possible over the northern High Plains vicinity on Thursday afternoon and evening. ...Deep South/TN Valley... TC Francine is forecast by NHC to be in a weakening phase on Thursday as it tracks northward across parts of the Lower MS Valley to Mid-South. Model consensus suggests the bulk of strong low-level wind fields will become increasingly confined within the northeast quadrant of the cyclone. This will yield decreasing low-level hodograph curvature through the period, initially along the central/northeast Gulf Coast and gradually expanding northward. This will result in decreasing overlap of favorable SRH with rich tropical moisture, characterized by 70s surface dew points. Tornado potential may be less than on D2, but should still have a diurnal morning to afternoon peak before diminishing during the latter half of D3. Confidence is low with the northern extent of the low-probability tornado threat, which will likely contain scant surface-based instability coincident with moderate to large SRH. The TN Valley vicinity appears to be the northern demarcation. ...Eastern MT to western Dakotas... The northern Rockies to Great Basin shortwave trough should shift east into the northern High Plains to central Rockies by Thursday evening. Guidance has above-average consistency with the depiction of an embedded impulse and attendant meridional mid-level jet impinging on the eastern MT/WY region during the late afternoon to early evening. This will increase large-scale ascent and deep-layer shear, becoming favorably timed with peak boundary-layer heating. Two convective regimes are apparent, one within the post-frontal upslope flow regime in central to eastern MT and the other near the lee surface trough/cyclone close to the MT/Dakotas border area. Isolated large hail will be favored in the western regime, while isolated severe gusts should be favored east. The primary limiting factor to greater severe probs is progged weak buoyancy, with pre-convective surface dew points around the upper 40s to low 50s. ..Grams.. 09/10/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Tue Sep 10 2024 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE DEEP SOUTH AND THE NORTHERN HIGH PLAINS... ...SUMMARY... A low-probability tornado threat may persist into Thursday across parts of the Deep South. Isolated large hail and severe gusts will be possible over the northern High Plains vicinity on Thursday afternoon and evening. ...Deep South/TN Valley... TC Francine is forecast by NHC to be in a weakening phase on Thursday as it tracks northward across parts of the Lower MS Valley to Mid-South. Model consensus suggests the bulk of strong low-level wind fields will become increasingly confined within the northeast quadrant of the cyclone. This will yield decreasing low-level hodograph curvature through the period, initially along the central/northeast Gulf Coast and gradually expanding northward. This will result in decreasing overlap of favorable SRH with rich tropical moisture, characterized by 70s surface dew points. Tornado potential may be less than on D2, but should still have a diurnal morning to afternoon peak before diminishing during the latter half of D3. Confidence is low with the northern extent of the low-probability tornado threat, which will likely contain scant surface-based instability coincident with moderate to large SRH. The TN Valley vicinity appears to be the northern demarcation. ...Eastern MT to western Dakotas... The northern Rockies to Great Basin shortwave trough should shift east into the northern High Plains to central Rockies by Thursday evening. Guidance has above-average consistency with the depiction of an embedded impulse and attendant meridional mid-level jet impinging on the eastern MT/WY region during the late afternoon to early evening. This will increase large-scale ascent and deep-layer shear, becoming favorably timed with peak boundary-layer heating. Two convective regimes are apparent, one within the post-frontal upslope flow regime in central to eastern MT and the other near the lee surface trough/cyclone close to the MT/Dakotas border area. Isolated large hail will be favored in the western regime, while isolated severe gusts should be favored east. The primary limiting factor to greater severe probs is progged weak buoyancy, with pre-convective surface dew points around the upper 40s to low 50s. ..Grams.. 09/10/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Tue Sep 10 2024 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE DEEP SOUTH AND THE NORTHERN HIGH PLAINS... ...SUMMARY... A low-probability tornado threat may persist into Thursday across parts of the Deep South. Isolated large hail and severe gusts will be possible over the northern High Plains vicinity on Thursday afternoon and evening. ...Deep South/TN Valley... TC Francine is forecast by NHC to be in a weakening phase on Thursday as it tracks northward across parts of the Lower MS Valley to Mid-South. Model consensus suggests the bulk of strong low-level wind fields will become increasingly confined within the northeast quadrant of the cyclone. This will yield decreasing low-level hodograph curvature through the period, initially along the central/northeast Gulf Coast and gradually expanding northward. This will result in decreasing overlap of favorable SRH with rich tropical moisture, characterized by 70s surface dew points. Tornado potential may be less than on D2, but should still have a diurnal morning to afternoon peak before diminishing during the latter half of D3. Confidence is low with the northern extent of the low-probability tornado threat, which will likely contain scant surface-based instability coincident with moderate to large SRH. The TN Valley vicinity appears to be the northern demarcation. ...Eastern MT to western Dakotas... The northern Rockies to Great Basin shortwave trough should shift east into the northern High Plains to central Rockies by Thursday evening. Guidance has above-average consistency with the depiction of an embedded impulse and attendant meridional mid-level jet impinging on the eastern MT/WY region during the late afternoon to early evening. This will increase large-scale ascent and deep-layer shear, becoming favorably timed with peak boundary-layer heating. Two convective regimes are apparent, one within the post-frontal upslope flow regime in central to eastern MT and the other near the lee surface trough/cyclone close to the MT/Dakotas border area. Isolated large hail will be favored in the western regime, while isolated severe gusts should be favored east. The primary limiting factor to greater severe probs is progged weak buoyancy, with pre-convective surface dew points around the upper 40s to low 50s. ..Grams.. 09/10/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Tue Sep 10 2024 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE DEEP SOUTH AND THE NORTHERN HIGH PLAINS... ...SUMMARY... A low-probability tornado threat may persist into Thursday across parts of the Deep South. Isolated large hail and severe gusts will be possible over the northern High Plains vicinity on Thursday afternoon and evening. ...Deep South/TN Valley... TC Francine is forecast by NHC to be in a weakening phase on Thursday as it tracks northward across parts of the Lower MS Valley to Mid-South. Model consensus suggests the bulk of strong low-level wind fields will become increasingly confined within the northeast quadrant of the cyclone. This will yield decreasing low-level hodograph curvature through the period, initially along the central/northeast Gulf Coast and gradually expanding northward. This will result in decreasing overlap of favorable SRH with rich tropical moisture, characterized by 70s surface dew points. Tornado potential may be less than on D2, but should still have a diurnal morning to afternoon peak before diminishing during the latter half of D3. Confidence is low with the northern extent of the low-probability tornado threat, which will likely contain scant surface-based instability coincident with moderate to large SRH. The TN Valley vicinity appears to be the northern demarcation. ...Eastern MT to western Dakotas... The northern Rockies to Great Basin shortwave trough should shift east into the northern High Plains to central Rockies by Thursday evening. Guidance has above-average consistency with the depiction of an embedded impulse and attendant meridional mid-level jet impinging on the eastern MT/WY region during the late afternoon to early evening. This will increase large-scale ascent and deep-layer shear, becoming favorably timed with peak boundary-layer heating. Two convective regimes are apparent, one within the post-frontal upslope flow regime in central to eastern MT and the other near the lee surface trough/cyclone close to the MT/Dakotas border area. Isolated large hail will be favored in the western regime, while isolated severe gusts should be favored east. The primary limiting factor to greater severe probs is progged weak buoyancy, with pre-convective surface dew points around the upper 40s to low 50s. ..Grams.. 09/10/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Sep 10 2024 Valid 111200Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... ...Synopsis... The upper trough over the western US will quickly intensify Wednesday, as a shortwave perturbation and mid-level jet streak move onshore over the West Coast. As the trough strengthens, mid-level flow over much of the West will increase. A surface low will deepen over the northern Great Basin, while a cold front moves onshore and also strengthens. To the east, TS Francine will approach the Gulf Coast with offshore winds likely over parts of the mid South. Strong surface winds, low humidity, and thunderstorms over parts of the West and central US will support critical fire-weather concerns Wednesday. ...Great Basin... Ahead of the deepening trough, a potent mid-level jet streak will move over parts of the western Great Basin beginning early Wednesday. A deepening surface low in parts of the eastern Basin will drive 20-25 mph winds over much of NV into western UT. Augmented by downslope flow off the Sierra and the approaching cold front, a brief period of winds of 25-30 mph will be possible along with RH below 15%. Widespread critical fire-weather conditions are likely over parts of the Great Basin. Fire-weather concerns should diminish behind the front as cooler and more quiescent conditions are expected behind the front into early Thursday. ...Lee of the Rockies and High Plains... As the trough approaches, height falls and stronger flow aloft will overspread the Rockies and High Plains. A surface low will deepen first in eastern MT, with a lee trough extending south into the central High Plains. Near the lee trough, strong southerly winds will overlap with areas of low RH and drying fine fuels. Elevated fire weather concerns are expected over parts of the High Plains Wednesday afternoon and evening. ...Mid South... As Francine approaches the Gulf Coast Wednesday and Wednesday night, offshore pressure gradients will increase over parts of the lower MS Valley and Mid South. While humidity values are not expected to be overly low with the tropical air mass approaching, strong gusts are expected to overlap with areas of relatively dry fuels and little recent rainfall. Brief elevated fire-weather conditions are possible before rain chances increase into early Thursday. ...Northwest Thunder... Ahead of the cold front, increasing mid-level moisture and strong lift from the trough will promote scattered thunderstorms Wednesday afternoon. Lightning may interact with areas of somewhat drier fuels over parts of the Northwest and northern Rockies before broader wetting rainfall develops. However, these storms will likely have higher precipitation efficiency with a cooler air mass and more plentiful Pacific moisture in place. This lends significant uncertainty on the threat for any lightning ignitions. ..Lyons.. 09/10/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Sep 10 2024 Valid 111200Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... ...Synopsis... The upper trough over the western US will quickly intensify Wednesday, as a shortwave perturbation and mid-level jet streak move onshore over the West Coast. As the trough strengthens, mid-level flow over much of the West will increase. A surface low will deepen over the northern Great Basin, while a cold front moves onshore and also strengthens. To the east, TS Francine will approach the Gulf Coast with offshore winds likely over parts of the mid South. Strong surface winds, low humidity, and thunderstorms over parts of the West and central US will support critical fire-weather concerns Wednesday. ...Great Basin... Ahead of the deepening trough, a potent mid-level jet streak will move over parts of the western Great Basin beginning early Wednesday. A deepening surface low in parts of the eastern Basin will drive 20-25 mph winds over much of NV into western UT. Augmented by downslope flow off the Sierra and the approaching cold front, a brief period of winds of 25-30 mph will be possible along with RH below 15%. Widespread critical fire-weather conditions are likely over parts of the Great Basin. Fire-weather concerns should diminish behind the front as cooler and more quiescent conditions are expected behind the front into early Thursday. ...Lee of the Rockies and High Plains... As the trough approaches, height falls and stronger flow aloft will overspread the Rockies and High Plains. A surface low will deepen first in eastern MT, with a lee trough extending south into the central High Plains. Near the lee trough, strong southerly winds will overlap with areas of low RH and drying fine fuels. Elevated fire weather concerns are expected over parts of the High Plains Wednesday afternoon and evening. ...Mid South... As Francine approaches the Gulf Coast Wednesday and Wednesday night, offshore pressure gradients will increase over parts of the lower MS Valley and Mid South. While humidity values are not expected to be overly low with the tropical air mass approaching, strong gusts are expected to overlap with areas of relatively dry fuels and little recent rainfall. Brief elevated fire-weather conditions are possible before rain chances increase into early Thursday. ...Northwest Thunder... Ahead of the cold front, increasing mid-level moisture and strong lift from the trough will promote scattered thunderstorms Wednesday afternoon. Lightning may interact with areas of somewhat drier fuels over parts of the Northwest and northern Rockies before broader wetting rainfall develops. However, these storms will likely have higher precipitation efficiency with a cooler air mass and more plentiful Pacific moisture in place. This lends significant uncertainty on the threat for any lightning ignitions. ..Lyons.. 09/10/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Sep 10 2024 Valid 111200Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... ...Synopsis... The upper trough over the western US will quickly intensify Wednesday, as a shortwave perturbation and mid-level jet streak move onshore over the West Coast. As the trough strengthens, mid-level flow over much of the West will increase. A surface low will deepen over the northern Great Basin, while a cold front moves onshore and also strengthens. To the east, TS Francine will approach the Gulf Coast with offshore winds likely over parts of the mid South. Strong surface winds, low humidity, and thunderstorms over parts of the West and central US will support critical fire-weather concerns Wednesday. ...Great Basin... Ahead of the deepening trough, a potent mid-level jet streak will move over parts of the western Great Basin beginning early Wednesday. A deepening surface low in parts of the eastern Basin will drive 20-25 mph winds over much of NV into western UT. Augmented by downslope flow off the Sierra and the approaching cold front, a brief period of winds of 25-30 mph will be possible along with RH below 15%. Widespread critical fire-weather conditions are likely over parts of the Great Basin. Fire-weather concerns should diminish behind the front as cooler and more quiescent conditions are expected behind the front into early Thursday. ...Lee of the Rockies and High Plains... As the trough approaches, height falls and stronger flow aloft will overspread the Rockies and High Plains. A surface low will deepen first in eastern MT, with a lee trough extending south into the central High Plains. Near the lee trough, strong southerly winds will overlap with areas of low RH and drying fine fuels. Elevated fire weather concerns are expected over parts of the High Plains Wednesday afternoon and evening. ...Mid South... As Francine approaches the Gulf Coast Wednesday and Wednesday night, offshore pressure gradients will increase over parts of the lower MS Valley and Mid South. While humidity values are not expected to be overly low with the tropical air mass approaching, strong gusts are expected to overlap with areas of relatively dry fuels and little recent rainfall. Brief elevated fire-weather conditions are possible before rain chances increase into early Thursday. ...Northwest Thunder... Ahead of the cold front, increasing mid-level moisture and strong lift from the trough will promote scattered thunderstorms Wednesday afternoon. Lightning may interact with areas of somewhat drier fuels over parts of the Northwest and northern Rockies before broader wetting rainfall develops. However, these storms will likely have higher precipitation efficiency with a cooler air mass and more plentiful Pacific moisture in place. This lends significant uncertainty on the threat for any lightning ignitions. ..Lyons.. 09/10/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Sep 10 2024 Valid 111200Z - 121200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE GREAT BASIN... ...Synopsis... The upper trough over the western US will quickly intensify Wednesday, as a shortwave perturbation and mid-level jet streak move onshore over the West Coast. As the trough strengthens, mid-level flow over much of the West will increase. A surface low will deepen over the northern Great Basin, while a cold front moves onshore and also strengthens. To the east, TS Francine will approach the Gulf Coast with offshore winds likely over parts of the mid South. Strong surface winds, low humidity, and thunderstorms over parts of the West and central US will support critical fire-weather concerns Wednesday. ...Great Basin... Ahead of the deepening trough, a potent mid-level jet streak will move over parts of the western Great Basin beginning early Wednesday. A deepening surface low in parts of the eastern Basin will drive 20-25 mph winds over much of NV into western UT. Augmented by downslope flow off the Sierra and the approaching cold front, a brief period of winds of 25-30 mph will be possible along with RH below 15%. Widespread critical fire-weather conditions are likely over parts of the Great Basin. Fire-weather concerns should diminish behind the front as cooler and more quiescent conditions are expected behind the front into early Thursday. ...Lee of the Rockies and High Plains... As the trough approaches, height falls and stronger flow aloft will overspread the Rockies and High Plains. A surface low will deepen first in eastern MT, with a lee trough extending south into the central High Plains. Near the lee trough, strong southerly winds will overlap with areas of low RH and drying fine fuels. Elevated fire weather concerns are expected over parts of the High Plains Wednesday afternoon and evening. ...Mid South... As Francine approaches the Gulf Coast Wednesday and Wednesday night, offshore pressure gradients will increase over parts of the lower MS Valley and Mid South. While humidity values are not expected to be overly low with the tropical air mass approaching, strong gusts are expected to overlap with areas of relatively dry fuels and little recent rainfall. Brief elevated fire-weather conditions are possible before rain chances increase into early Thursday. ...Northwest Thunder... Ahead of the cold front, increasing mid-level moisture and strong lift from the trough will promote scattered thunderstorms Wednesday afternoon. Lightning may interact with areas of somewhat drier fuels over parts of the Northwest and northern Rockies before broader wetting rainfall develops. However, these storms will likely have higher precipitation efficiency with a cooler air mass and more plentiful Pacific moisture in place. This lends significant uncertainty on the threat for any lightning ignitions. ..Lyons.. 09/10/2024 ...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 0159 AM CDT Tue Sep 10 2024 Valid 101200Z - 111200Z ...Synopsis... Broad troughing over the Northwest will gradually intensify later today and tonight, as a stronger shortwave and mid-level jet approach from the eastern Pacific. Increasing flow aloft will move inland, supporting the potential for strong surface winds and low humidity over parts of the Northwest and Great Basin. Elevated to near-critical fire-weather conditions are likely. ...Great Basin... As the upper trough shifts east, mid-level flow should strengthen over parts of the western Great Basin. Gusty downslope winds are likely in the lee of the Sierra and across parts of southern NV and western UT. Surface winds of 15-25 mph should overlap with RH below 15%, and within areas of dry fuels this afternoon. Elevated to near-critical fire-weather conditions are likely across much of NV and into portions of northern CA, southern ID and far western UT. Confidence in the development of nearly to briefly critical meteorological conditions is highest over parts of southern NV where winds are expected to be slightly stronger. However, fuels here are also slightly less receptive, and the overlap of favorable wind/RH may also be briefer. Thus, confidence remains too low for critical highlights currently. ...Cascades and Columbia Gorge... Increasing mid-level winds will combine with a strong onshore pressure gradient behind the departing cold front to drive 15-20 mph winds through Cascade Gaps and into the western Columbia Basin. While cooler and more moderate, pockets of RH below 25% should overlap with the stronger winds. The duration of these breezy and somewhat dry conditions may be somewhat limited, but elevated to briefly critical fire weather conditions are possible within dry fuels. ..Lyons.. 09/10/2024 ...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 0159 AM CDT Tue Sep 10 2024 Valid 101200Z - 111200Z ...Synopsis... Broad troughing over the Northwest will gradually intensify later today and tonight, as a stronger shortwave and mid-level jet approach from the eastern Pacific. Increasing flow aloft will move inland, supporting the potential for strong surface winds and low humidity over parts of the Northwest and Great Basin. Elevated to near-critical fire-weather conditions are likely. ...Great Basin... As the upper trough shifts east, mid-level flow should strengthen over parts of the western Great Basin. Gusty downslope winds are likely in the lee of the Sierra and across parts of southern NV and western UT. Surface winds of 15-25 mph should overlap with RH below 15%, and within areas of dry fuels this afternoon. Elevated to near-critical fire-weather conditions are likely across much of NV and into portions of northern CA, southern ID and far western UT. Confidence in the development of nearly to briefly critical meteorological conditions is highest over parts of southern NV where winds are expected to be slightly stronger. However, fuels here are also slightly less receptive, and the overlap of favorable wind/RH may also be briefer. Thus, confidence remains too low for critical highlights currently. ...Cascades and Columbia Gorge... Increasing mid-level winds will combine with a strong onshore pressure gradient behind the departing cold front to drive 15-20 mph winds through Cascade Gaps and into the western Columbia Basin. While cooler and more moderate, pockets of RH below 25% should overlap with the stronger winds. The duration of these breezy and somewhat dry conditions may be somewhat limited, but elevated to briefly critical fire weather conditions are possible within dry fuels. ..Lyons.. 09/10/2024 ...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 0159 AM CDT Tue Sep 10 2024 Valid 101200Z - 111200Z ...Synopsis... Broad troughing over the Northwest will gradually intensify later today and tonight, as a stronger shortwave and mid-level jet approach from the eastern Pacific. Increasing flow aloft will move inland, supporting the potential for strong surface winds and low humidity over parts of the Northwest and Great Basin. Elevated to near-critical fire-weather conditions are likely. ...Great Basin... As the upper trough shifts east, mid-level flow should strengthen over parts of the western Great Basin. Gusty downslope winds are likely in the lee of the Sierra and across parts of southern NV and western UT. Surface winds of 15-25 mph should overlap with RH below 15%, and within areas of dry fuels this afternoon. Elevated to near-critical fire-weather conditions are likely across much of NV and into portions of northern CA, southern ID and far western UT. Confidence in the development of nearly to briefly critical meteorological conditions is highest over parts of southern NV where winds are expected to be slightly stronger. However, fuels here are also slightly less receptive, and the overlap of favorable wind/RH may also be briefer. Thus, confidence remains too low for critical highlights currently. ...Cascades and Columbia Gorge... Increasing mid-level winds will combine with a strong onshore pressure gradient behind the departing cold front to drive 15-20 mph winds through Cascade Gaps and into the western Columbia Basin. While cooler and more moderate, pockets of RH below 25% should overlap with the stronger winds. The duration of these breezy and somewhat dry conditions may be somewhat limited, but elevated to briefly critical fire weather conditions are possible within dry fuels. ..Lyons.. 09/10/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more