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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Sun Sep 29 2024 Valid 291630Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis... A relatively quiet convective day is expected across the CONUS today. Over portions of UT, weak/peripheral midlevel height falls will promote isolated high-based thunderstorms capable of locally strong gusts, aided by inverted-V thermodynamic profiles. Weak instability and flow/shear should limit thunderstorm intensity and organization. Farther east, isolated thunderstorms will be possible this afternoon and evening over portions of the OH Valley into the Mid-Atlantic -- ahead of a vertically stacked/weakening cyclone. Very poor deep-layer lapse rates and warm air aloft may limit lightning over many areas, though a few isolated flashes cannot be ruled out, given some large-scale ascent. Ahead of a quasi-stationary front draped across northern FL, diurnal heating of a moist/uncapped air mass will support isolated to widely scattered thunderstorms across the FL Peninsula this afternoon. Locally strong water-loaded downbursts could accompany a couple storms over northeast FL, where low-level convergence and midlevel flow will be slightly stronger. However, poor midlevel lapse rates and only marginal deep-layer shear should limit the severe threat. ..Weinman.. 09/29/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CDT Sun Sep 29 2024 Valid 291630Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis... A relatively quiet convective day is expected across the CONUS today. Over portions of UT, weak/peripheral midlevel height falls will promote isolated high-based thunderstorms capable of locally strong gusts, aided by inverted-V thermodynamic profiles. Weak instability and flow/shear should limit thunderstorm intensity and organization. Farther east, isolated thunderstorms will be possible this afternoon and evening over portions of the OH Valley into the Mid-Atlantic -- ahead of a vertically stacked/weakening cyclone. Very poor deep-layer lapse rates and warm air aloft may limit lightning over many areas, though a few isolated flashes cannot be ruled out, given some large-scale ascent. Ahead of a quasi-stationary front draped across northern FL, diurnal heating of a moist/uncapped air mass will support isolated to widely scattered thunderstorms across the FL Peninsula this afternoon. Locally strong water-loaded downbursts could accompany a couple storms over northeast FL, where low-level convergence and midlevel flow will be slightly stronger. However, poor midlevel lapse rates and only marginal deep-layer shear should limit the severe threat. ..Weinman.. 09/29/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 1034 AM CDT Sun Sep 29 2024 Valid 291700Z - 301200Z ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO SOUTHERN NORTH DAKOTA... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL WYOMING... ...Northern Rockies/Plains... The primary adjustment for this update is introducing a Critical risk area to parts of central WY where morning guidance has come into reasonably good agreement in a few hours of sustained 20-25 mph winds with RH values near 15%. Additionally, the Elevated risk areas across the northern Rockies and northern Plains have been combined and expanded into eastern MT to account for two trends. First, morning surface observations are drier/windier along the surface trough that is in place across the High Plains than previously anticipated by guidance. This trend suggests that elevated to critical fire weather conditions may be more pervasive than depicted by the previous outlook. Second, dry and windy conditions are likely overnight tonight as a dry cold front pushes southeast across MT and the western Dakotas. An influx of dry air will limit nocturnal RH recovery with most 12z guidance suggesting that 15-25% RH and 20-30 mph winds will be common for a few hours in the post-frontal regime. ...Utah... Very isolated thunderstorms are expected this afternoon across central UT. The 12z SLC sounding sampled very dry boundary-layer conditions, but cold temperatures aloft with adequate moisture for weak convection. Additionally, recent visible imagery already shows shallow cumulus developing atop the boundary layer. As such, a few dry thunderstorms appear possible and may overlap with the dry fuels that are in place across west-central UT. However, thunderstorm development appears most probable across central UT where orographic ascent will bolster the relatively weak ascent over the region. Given the low probability for dry lightning over receptive fuels, additional risk highlights were withheld. ..Moore.. 09/29/2024 .PREV DISCUSSION... /ISSUED 1228 AM CDT Sun Sep 29 2024/ ...Synopsis... Elevated to critical fire-weather conditions are expected across much of the Intermountain West into the northern Great Plains as a progressive mid-level trough traverses the Canadian prairies. The deepening surface cyclone and tightening surface pressure gradients associated with this trough will result in widespread dry and windy conditions over receptive fuels. A narrow Critical area has been maintained where the highest confidence in 20-25 MPH winds and relative humidity values below 15% are expected to overlap with ERC fuels exceeding the 95th annual percentiles. Portions of central and eastern Wyoming may also experience locally critical conditions, though confidence in the magnitude and spatial extent of surface winds precludes Critical highlights at this time. Further west, elevated fire-weather conditions are expected across central and eastern Nevada into western Utah, as well as portions of Columbia River Basin in Washington. Winds in the Columbia River Basin could be as high as 20-25 MPH, but forecast guidance shows significant spread in the forecast boundary-layer relative humidity values (15-25%). Across the Great Basin, winds will generally remain in the 15-20 MPH range with relative humidity values of 10-15%. ...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 0728 AM CDT Sun Sep 29 2024 Valid 291300Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis/Discussion... A highly amplified, slow-moving, mid/upper-level pattern will persist over much of the CONUS, south of a progressive northern stream near and north of the Canadian border. A norther-stream trough, nearly synoptic in scale, is apparent in moisture-channel imagery from central/southwestern BC to near-coastal WA/OR. This feature should amplify and move eastward across southwestern Canada and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow. Weak, basal height falls and modest midlevel moisture will contribute to the potential for isolated, high-based convection over portions of UT, some of which may extend deep enough to generate lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area. As the northern-stream trough moves away from CA, a formerly cut-off low now moving ashore into south-central CA will become cut off again, and drift southward/southwestward back toward the Pacific by the end of the period. Ridging will weaken greatly over the northern Plains and Upper Midwest ahead of the northern-stream trough, but will persist at its root over the Four Corners region. To its east, a longstanding, stacked, gradually filling cyclone will drift erratically eastward over the TN/KY border area, possibly devolving into an open-wave trough by the end of the period. Associated convection to its east will encounter a relatively warm/ stable layer in mid/upper levels, limiting but not entirely suppressing potential for convection to reach into icing layers suitable for lightning. As such, isolated thunder will be possible from the central Appalachians to the Tidewater. Although warm midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over northern FL will support sporadic thunderstorm potential, mainly from midday through early evening. ..Edwards/Broyles.. 09/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0728 AM CDT Sun Sep 29 2024 Valid 291300Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis/Discussion... A highly amplified, slow-moving, mid/upper-level pattern will persist over much of the CONUS, south of a progressive northern stream near and north of the Canadian border. A norther-stream trough, nearly synoptic in scale, is apparent in moisture-channel imagery from central/southwestern BC to near-coastal WA/OR. This feature should amplify and move eastward across southwestern Canada and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow. Weak, basal height falls and modest midlevel moisture will contribute to the potential for isolated, high-based convection over portions of UT, some of which may extend deep enough to generate lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area. As the northern-stream trough moves away from CA, a formerly cut-off low now moving ashore into south-central CA will become cut off again, and drift southward/southwestward back toward the Pacific by the end of the period. Ridging will weaken greatly over the northern Plains and Upper Midwest ahead of the northern-stream trough, but will persist at its root over the Four Corners region. To its east, a longstanding, stacked, gradually filling cyclone will drift erratically eastward over the TN/KY border area, possibly devolving into an open-wave trough by the end of the period. Associated convection to its east will encounter a relatively warm/ stable layer in mid/upper levels, limiting but not entirely suppressing potential for convection to reach into icing layers suitable for lightning. As such, isolated thunder will be possible from the central Appalachians to the Tidewater. Although warm midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over northern FL will support sporadic thunderstorm potential, mainly from midday through early evening. ..Edwards/Broyles.. 09/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0728 AM CDT Sun Sep 29 2024 Valid 291300Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis/Discussion... A highly amplified, slow-moving, mid/upper-level pattern will persist over much of the CONUS, south of a progressive northern stream near and north of the Canadian border. A norther-stream trough, nearly synoptic in scale, is apparent in moisture-channel imagery from central/southwestern BC to near-coastal WA/OR. This feature should amplify and move eastward across southwestern Canada and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow. Weak, basal height falls and modest midlevel moisture will contribute to the potential for isolated, high-based convection over portions of UT, some of which may extend deep enough to generate lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area. As the northern-stream trough moves away from CA, a formerly cut-off low now moving ashore into south-central CA will become cut off again, and drift southward/southwestward back toward the Pacific by the end of the period. Ridging will weaken greatly over the northern Plains and Upper Midwest ahead of the northern-stream trough, but will persist at its root over the Four Corners region. To its east, a longstanding, stacked, gradually filling cyclone will drift erratically eastward over the TN/KY border area, possibly devolving into an open-wave trough by the end of the period. Associated convection to its east will encounter a relatively warm/ stable layer in mid/upper levels, limiting but not entirely suppressing potential for convection to reach into icing layers suitable for lightning. As such, isolated thunder will be possible from the central Appalachians to the Tidewater. Although warm midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over northern FL will support sporadic thunderstorm potential, mainly from midday through early evening. ..Edwards/Broyles.. 09/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0728 AM CDT Sun Sep 29 2024 Valid 291300Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis/Discussion... A highly amplified, slow-moving, mid/upper-level pattern will persist over much of the CONUS, south of a progressive northern stream near and north of the Canadian border. A norther-stream trough, nearly synoptic in scale, is apparent in moisture-channel imagery from central/southwestern BC to near-coastal WA/OR. This feature should amplify and move eastward across southwestern Canada and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow. Weak, basal height falls and modest midlevel moisture will contribute to the potential for isolated, high-based convection over portions of UT, some of which may extend deep enough to generate lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area. As the northern-stream trough moves away from CA, a formerly cut-off low now moving ashore into south-central CA will become cut off again, and drift southward/southwestward back toward the Pacific by the end of the period. Ridging will weaken greatly over the northern Plains and Upper Midwest ahead of the northern-stream trough, but will persist at its root over the Four Corners region. To its east, a longstanding, stacked, gradually filling cyclone will drift erratically eastward over the TN/KY border area, possibly devolving into an open-wave trough by the end of the period. Associated convection to its east will encounter a relatively warm/ stable layer in mid/upper levels, limiting but not entirely suppressing potential for convection to reach into icing layers suitable for lightning. As such, isolated thunder will be possible from the central Appalachians to the Tidewater. Although warm midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over northern FL will support sporadic thunderstorm potential, mainly from midday through early evening. ..Edwards/Broyles.. 09/29/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0728 AM CDT Sun Sep 29 2024 Valid 291300Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast for today. ...Synopsis/Discussion... A highly amplified, slow-moving, mid/upper-level pattern will persist over much of the CONUS, south of a progressive northern stream near and north of the Canadian border. A norther-stream trough, nearly synoptic in scale, is apparent in moisture-channel imagery from central/southwestern BC to near-coastal WA/OR. This feature should amplify and move eastward across southwestern Canada and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow. Weak, basal height falls and modest midlevel moisture will contribute to the potential for isolated, high-based convection over portions of UT, some of which may extend deep enough to generate lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area. As the northern-stream trough moves away from CA, a formerly cut-off low now moving ashore into south-central CA will become cut off again, and drift southward/southwestward back toward the Pacific by the end of the period. Ridging will weaken greatly over the northern Plains and Upper Midwest ahead of the northern-stream trough, but will persist at its root over the Four Corners region. To its east, a longstanding, stacked, gradually filling cyclone will drift erratically eastward over the TN/KY border area, possibly devolving into an open-wave trough by the end of the period. Associated convection to its east will encounter a relatively warm/ stable layer in mid/upper levels, limiting but not entirely suppressing potential for convection to reach into icing layers suitable for lightning. As such, isolated thunder will be possible from the central Appalachians to the Tidewater. Although warm midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over northern FL will support sporadic thunderstorm potential, mainly from midday through early evening. ..Edwards/Broyles.. 09/29/2024 Read more

804
ABPZ20 KNHC 291133
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Sep 29 2024

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

Offshore of Southern and Southwestern Mexico:
An area of low pressure is forecast to develop off the coast of
southern or southwestern Mexico in a day or two. Thereafter,
environmental conditions appear generally favorable for additional
development, and a tropical depression could form by the middle to
latter part of this week while the system drifts slowly westward or
northwestward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...medium...40 percent.

$$
Forecaster Papin

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Sun Sep 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... Zonal flow aloft is expected to persist into late next week across the CONUS. The upper-level jet will be displaced northward to near and along the Canadian border. As successive shortwave troughs move through that zone of stronger flow, cooler/drier air will move southward into much of the Plains and parts of the Midwest/Northeast. By next weekend, there is some potential for some upper-level flow amplification with a ridge developing in the West and shortwave troughs moving into the eastern third of the CONUS. However, models remain rather divergent in their exact depiction of this evolution (the ECMWF deterministic/ensemble is more amplified than its GFS counterparts). Further increasing uncertainty, the degree of moisture return ahead of any potential shortwave trough is questionable given the expected frontal progression to along/near the Gulf Coast. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Sun Sep 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... Zonal flow aloft is expected to persist into late next week across the CONUS. The upper-level jet will be displaced northward to near and along the Canadian border. As successive shortwave troughs move through that zone of stronger flow, cooler/drier air will move southward into much of the Plains and parts of the Midwest/Northeast. By next weekend, there is some potential for some upper-level flow amplification with a ridge developing in the West and shortwave troughs moving into the eastern third of the CONUS. However, models remain rather divergent in their exact depiction of this evolution (the ECMWF deterministic/ensemble is more amplified than its GFS counterparts). Further increasing uncertainty, the degree of moisture return ahead of any potential shortwave trough is questionable given the expected frontal progression to along/near the Gulf Coast. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Sun Sep 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... Zonal flow aloft is expected to persist into late next week across the CONUS. The upper-level jet will be displaced northward to near and along the Canadian border. As successive shortwave troughs move through that zone of stronger flow, cooler/drier air will move southward into much of the Plains and parts of the Midwest/Northeast. By next weekend, there is some potential for some upper-level flow amplification with a ridge developing in the West and shortwave troughs moving into the eastern third of the CONUS. However, models remain rather divergent in their exact depiction of this evolution (the ECMWF deterministic/ensemble is more amplified than its GFS counterparts). Further increasing uncertainty, the degree of moisture return ahead of any potential shortwave trough is questionable given the expected frontal progression to along/near the Gulf Coast. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Sun Sep 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... Zonal flow aloft is expected to persist into late next week across the CONUS. The upper-level jet will be displaced northward to near and along the Canadian border. As successive shortwave troughs move through that zone of stronger flow, cooler/drier air will move southward into much of the Plains and parts of the Midwest/Northeast. By next weekend, there is some potential for some upper-level flow amplification with a ridge developing in the West and shortwave troughs moving into the eastern third of the CONUS. However, models remain rather divergent in their exact depiction of this evolution (the ECMWF deterministic/ensemble is more amplified than its GFS counterparts). Further increasing uncertainty, the degree of moisture return ahead of any potential shortwave trough is questionable given the expected frontal progression to along/near the Gulf Coast. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Sun Sep 29 2024 Valid 021200Z - 071200Z ...DISCUSSION... Zonal flow aloft is expected to persist into late next week across the CONUS. The upper-level jet will be displaced northward to near and along the Canadian border. As successive shortwave troughs move through that zone of stronger flow, cooler/drier air will move southward into much of the Plains and parts of the Midwest/Northeast. By next weekend, there is some potential for some upper-level flow amplification with a ridge developing in the West and shortwave troughs moving into the eastern third of the CONUS. However, models remain rather divergent in their exact depiction of this evolution (the ECMWF deterministic/ensemble is more amplified than its GFS counterparts). Further increasing uncertainty, the degree of moisture return ahead of any potential shortwave trough is questionable given the expected frontal progression to along/near the Gulf Coast. Read more