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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Sat Sep 20 2025 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH TEXAS...THE MIDDLE MISSOURI VALLEY...AND THE OHIO VALLEY INTO THE GREAT LAKES... ...SUMMARY... Isolated severe thunderstorms are possible across parts of north Texas and the Middle Missouri Valley, with the main risk being large hail. A few strong to severe thunderstorms capable of locally damaging gusts are possible across parts of the Ohio Valley into the Great Lakes. ...North Texas... Convection will likely be ongoing across southwest OK into western north TX at the start of the forecast period, which should lay out an outflow boundary across parts of north TX. Along/south of the outflow boundary and to the east of a lee trough/dryline feature, boundary-layer moisture advection and ample diurnal heating beneath relatively steep midlevel lapse rates will contribute to strong surface-based buoyancy and minimal inhibition by the afternoon. Aided by a glancing midlevel wave and related jet streak crossing western OK, isolated to widely scattered thunderstorms are expected near the lee trough and residual outflow boundary during the afternoon. A long/straight hodograph (around 40-50 kt of effective shear) and the aforementioned buoyancy should promote a couple splitting supercell structures, posing a risk of large hail. Severe wind gusts will also be possible, especially with any convective clustering that occurs with southeastward extent. ...Ohio Valley and Great Lakes... Downstream of a midlevel trough moving across the Upper MS Valley, broad/enhanced midlevel southwesterly flow will overspread a weak to moderately unstable and uncapped warm sector extending from the OH Valley into the Great Lakes. Potentially aided by a convectively augmented midlevel impulse moving into the Lower OH Valley, widely scattered thunderstorms are expected during the afternoon. Around 20-25 kt of effective shear and a warm/moist PBL will favor a few loosely organized multicell clusters, capable of producing locally damaging gusts through the afternoon. ...Middle Missouri Valley... Within the base of a midlevel trough over the Upper MS Valley, isolated thunderstorms should develop near a weak surface low near southeast SD. While boundary-layer moisture will be limited, cold temperatures aloft/steep lapse rates and sufficient buoyancy should support a couple loosely organized cells. Marginally severe hail will be possible with the stronger storms that evolve during the evening into overnight hours. ..Weinman.. 09/20/2025 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...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 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...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 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...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 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...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 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...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 1148 AM CDT Sat Sep 20 2025 Valid 201700Z - 211200Z ...North Cascades into the Columbia Basin... Current observations reveal significant drying on the western fringes of the Columbia Basin where relative humidity has already fallen below 20%, coincident with dewpoints around 20F. An approaching mid-level trough with accompanying increasing west/southwest aloft along with efficient boundary layer mixing under mostly clear skies will support increasing west/southwest winds in the lee of the Cascades and Columbia Basin this afternoon. A shallow temperature inversion within the basin will steadily erode, resulting in sustained west to southwest winds of 10-15 mph (20 mph in Cascade gaps) and relative humidity dropping as low as 10% this afternoon. Elevated highlights were maintained with expected dry and breezy conditions this afternoon amid dry fuels, where ERC values around the 80th percentile remain on the leeward slopes of the Cascades. ..Williams.. 09/20/2025 .PREV DISCUSSION... /ISSUED 1254 AM CDT Sat Sep 20 2025/ ...Synopsis... Elevated fire-weather highlights have been maintained over portions of the eastern North Cascades into the Columbia Basin, associated with west-southwesterly flow aloft from a mid-level trough approaching the U.S./Canada west coast. Weak surface winds and high precipitable water content across the rest of the continental U.S. preclude any other fire-weather highlights. ...North Cascades into the Columbia Basin... Westerly flow aloft will support downslope winds across the North Cascades, with winds of 10-15 MPH (locally as high as 20 MPH in the Cascade gaps) forecast along with relative humidity around 15-20%. With ERCs near the 80th annual percentile, at least Elevated fire-weather highlights are to be maintained today -- though fire-weather concerns are generally limited by the lack of appreciable surface winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Sep 20 2025 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... Visible-satellite imagery late this morning shows a couple of small thunderstorm clusters over parts of the Ozarks into northeast OK and mostly clear skies farther west and southwest over OK into the TX Panhandle. Surface analysis places a zone of outflow extending from west-central AR northwestward into north-central OK. The primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast by mid-late afternoon across the Marginal Risk. A relatively non-descript upper pattern, north of a flattened upper ridge, features a couple of very minor perturbations slowly moving east across the central High Plains into the mid MS Valley, to the south of more amplified disturbances over the upper MS Valley and ND. Weak capping and the aforementioned seasonably moist airmass will favor isolated to scattered thunderstorms developing near the front and outflow late this afternoon into the evening. Diurnal steepening of low-level lapse rates may yield an isolated risk for localized severe gusts and perhaps marginally severe hail. This activity will likely diminish by mid evening owing to the loss of heating. ...Upper Midwest/Great Lakes... An upper trough centered near the IA/WI/MN/IL border will continue to slowly migrate east across WI/northern IL today. Similar to areas farther southwest over the south-central Plains, a seasonably moist will undergo some heating in areas void of thicker cloud cover and aid in 1000 J/kg MLCAPE developing over WI according to forecast soundings. Weak 0-6 km shear (i.e., < 20 kt) should temper updraft organization and limit storm intensity. Nonetheless, a couple of strong gusts or small hail may occur with the more vigorous storms this afternoon. ..Smith/Wendt.. 09/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Sep 20 2025 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... Visible-satellite imagery late this morning shows a couple of small thunderstorm clusters over parts of the Ozarks into northeast OK and mostly clear skies farther west and southwest over OK into the TX Panhandle. Surface analysis places a zone of outflow extending from west-central AR northwestward into north-central OK. The primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast by mid-late afternoon across the Marginal Risk. A relatively non-descript upper pattern, north of a flattened upper ridge, features a couple of very minor perturbations slowly moving east across the central High Plains into the mid MS Valley, to the south of more amplified disturbances over the upper MS Valley and ND. Weak capping and the aforementioned seasonably moist airmass will favor isolated to scattered thunderstorms developing near the front and outflow late this afternoon into the evening. Diurnal steepening of low-level lapse rates may yield an isolated risk for localized severe gusts and perhaps marginally severe hail. This activity will likely diminish by mid evening owing to the loss of heating. ...Upper Midwest/Great Lakes... An upper trough centered near the IA/WI/MN/IL border will continue to slowly migrate east across WI/northern IL today. Similar to areas farther southwest over the south-central Plains, a seasonably moist will undergo some heating in areas void of thicker cloud cover and aid in 1000 J/kg MLCAPE developing over WI according to forecast soundings. Weak 0-6 km shear (i.e., < 20 kt) should temper updraft organization and limit storm intensity. Nonetheless, a couple of strong gusts or small hail may occur with the more vigorous storms this afternoon. ..Smith/Wendt.. 09/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Sep 20 2025 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... Visible-satellite imagery late this morning shows a couple of small thunderstorm clusters over parts of the Ozarks into northeast OK and mostly clear skies farther west and southwest over OK into the TX Panhandle. Surface analysis places a zone of outflow extending from west-central AR northwestward into north-central OK. The primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast by mid-late afternoon across the Marginal Risk. A relatively non-descript upper pattern, north of a flattened upper ridge, features a couple of very minor perturbations slowly moving east across the central High Plains into the mid MS Valley, to the south of more amplified disturbances over the upper MS Valley and ND. Weak capping and the aforementioned seasonably moist airmass will favor isolated to scattered thunderstorms developing near the front and outflow late this afternoon into the evening. Diurnal steepening of low-level lapse rates may yield an isolated risk for localized severe gusts and perhaps marginally severe hail. This activity will likely diminish by mid evening owing to the loss of heating. ...Upper Midwest/Great Lakes... An upper trough centered near the IA/WI/MN/IL border will continue to slowly migrate east across WI/northern IL today. Similar to areas farther southwest over the south-central Plains, a seasonably moist will undergo some heating in areas void of thicker cloud cover and aid in 1000 J/kg MLCAPE developing over WI according to forecast soundings. Weak 0-6 km shear (i.e., < 20 kt) should temper updraft organization and limit storm intensity. Nonetheless, a couple of strong gusts or small hail may occur with the more vigorous storms this afternoon. ..Smith/Wendt.. 09/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Sep 20 2025 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... Visible-satellite imagery late this morning shows a couple of small thunderstorm clusters over parts of the Ozarks into northeast OK and mostly clear skies farther west and southwest over OK into the TX Panhandle. Surface analysis places a zone of outflow extending from west-central AR northwestward into north-central OK. The primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast by mid-late afternoon across the Marginal Risk. A relatively non-descript upper pattern, north of a flattened upper ridge, features a couple of very minor perturbations slowly moving east across the central High Plains into the mid MS Valley, to the south of more amplified disturbances over the upper MS Valley and ND. Weak capping and the aforementioned seasonably moist airmass will favor isolated to scattered thunderstorms developing near the front and outflow late this afternoon into the evening. Diurnal steepening of low-level lapse rates may yield an isolated risk for localized severe gusts and perhaps marginally severe hail. This activity will likely diminish by mid evening owing to the loss of heating. ...Upper Midwest/Great Lakes... An upper trough centered near the IA/WI/MN/IL border will continue to slowly migrate east across WI/northern IL today. Similar to areas farther southwest over the south-central Plains, a seasonably moist will undergo some heating in areas void of thicker cloud cover and aid in 1000 J/kg MLCAPE developing over WI according to forecast soundings. Weak 0-6 km shear (i.e., < 20 kt) should temper updraft organization and limit storm intensity. Nonetheless, a couple of strong gusts or small hail may occur with the more vigorous storms this afternoon. ..Smith/Wendt.. 09/20/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Sep 20 2025 Valid 201630Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... Visible-satellite imagery late this morning shows a couple of small thunderstorm clusters over parts of the Ozarks into northeast OK and mostly clear skies farther west and southwest over OK into the TX Panhandle. Surface analysis places a zone of outflow extending from west-central AR northwestward into north-central OK. The primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast by mid-late afternoon across the Marginal Risk. A relatively non-descript upper pattern, north of a flattened upper ridge, features a couple of very minor perturbations slowly moving east across the central High Plains into the mid MS Valley, to the south of more amplified disturbances over the upper MS Valley and ND. Weak capping and the aforementioned seasonably moist airmass will favor isolated to scattered thunderstorms developing near the front and outflow late this afternoon into the evening. Diurnal steepening of low-level lapse rates may yield an isolated risk for localized severe gusts and perhaps marginally severe hail. This activity will likely diminish by mid evening owing to the loss of heating. ...Upper Midwest/Great Lakes... An upper trough centered near the IA/WI/MN/IL border will continue to slowly migrate east across WI/northern IL today. Similar to areas farther southwest over the south-central Plains, a seasonably moist will undergo some heating in areas void of thicker cloud cover and aid in 1000 J/kg MLCAPE developing over WI according to forecast soundings. Weak 0-6 km shear (i.e., < 20 kt) should temper updraft organization and limit storm intensity. Nonetheless, a couple of strong gusts or small hail may occur with the more vigorous storms this afternoon. ..Smith/Wendt.. 09/20/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0738 AM CDT Sat Sep 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... A small cluster of thunderstorms across northeast OK, southwest MO, and northwest AR this morning has remained mostly sub-severe overnight owing to weak instability and deep-layer shear. Current expectations are for this activity to further weaken as it spreads eastward across AR and southern MO through mid/late morning. Outflow from these thunderstorms has surged southward across much of OK per radar imagery. Recent surface observations also show the primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast to exist this afternoon along/south of the front where daytime heating occurs. Large-scale ascent aloft will remain nebulous/weak, with multiple low-amplitude mid-level perturbations present on the eastern periphery of upper ridging centered over Mexico and the Southwest. Still, isolated to scattered thunderstorms should develop this afternoon and evening, potentially along and south of the residual outflow boundary from the ongoing convection this morning. As low-level lapse rates become steepened through the day, isolated strong to severe gusts may occur with the more robust thunderstorms that form. Even though deep-layer shear will remain meager, modestly steepened mid-level lapse rates and cool temperatures aloft may also support occasional hail. The Marginal Risk has been adjusted for the latest guidance and observational trends, with somewhat greater confidence in convection occurring across the OK/TX Panhandles into OK along/near the outflow boundary compared to locations farther north in KS along the front. ...Upper Midwest/Great Lakes... A weak upper trough over the Upper Midwest this morning will translate slowly eastward across parts of the OH Valley and Upper Great Lakes through the period. A seasonably moist low-level airmass will remain over these areas along/south of a front, but mid-level lapse rates are expected to remain quite poor. Ongoing precipitation and cloud cover should also temper destabilization to some degree through this afternoon, with only weak MLCAPE forecast to develop. While isolated strong/gusty winds and small hail may occur with any of the stronger cores that can form later this afternoon across parts of WI into northern IL/IN and southern Lower MI, the overall severe threat appears too limited to include low severe probabilities at this time. ..Gleason/Grams.. 09/20/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0738 AM CDT Sat Sep 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... A small cluster of thunderstorms across northeast OK, southwest MO, and northwest AR this morning has remained mostly sub-severe overnight owing to weak instability and deep-layer shear. Current expectations are for this activity to further weaken as it spreads eastward across AR and southern MO through mid/late morning. Outflow from these thunderstorms has surged southward across much of OK per radar imagery. Recent surface observations also show the primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast to exist this afternoon along/south of the front where daytime heating occurs. Large-scale ascent aloft will remain nebulous/weak, with multiple low-amplitude mid-level perturbations present on the eastern periphery of upper ridging centered over Mexico and the Southwest. Still, isolated to scattered thunderstorms should develop this afternoon and evening, potentially along and south of the residual outflow boundary from the ongoing convection this morning. As low-level lapse rates become steepened through the day, isolated strong to severe gusts may occur with the more robust thunderstorms that form. Even though deep-layer shear will remain meager, modestly steepened mid-level lapse rates and cool temperatures aloft may also support occasional hail. The Marginal Risk has been adjusted for the latest guidance and observational trends, with somewhat greater confidence in convection occurring across the OK/TX Panhandles into OK along/near the outflow boundary compared to locations farther north in KS along the front. ...Upper Midwest/Great Lakes... A weak upper trough over the Upper Midwest this morning will translate slowly eastward across parts of the OH Valley and Upper Great Lakes through the period. A seasonably moist low-level airmass will remain over these areas along/south of a front, but mid-level lapse rates are expected to remain quite poor. Ongoing precipitation and cloud cover should also temper destabilization to some degree through this afternoon, with only weak MLCAPE forecast to develop. While isolated strong/gusty winds and small hail may occur with any of the stronger cores that can form later this afternoon across parts of WI into northern IL/IN and southern Lower MI, the overall severe threat appears too limited to include low severe probabilities at this time. ..Gleason/Grams.. 09/20/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0738 AM CDT Sat Sep 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... A small cluster of thunderstorms across northeast OK, southwest MO, and northwest AR this morning has remained mostly sub-severe overnight owing to weak instability and deep-layer shear. Current expectations are for this activity to further weaken as it spreads eastward across AR and southern MO through mid/late morning. Outflow from these thunderstorms has surged southward across much of OK per radar imagery. Recent surface observations also show the primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast to exist this afternoon along/south of the front where daytime heating occurs. Large-scale ascent aloft will remain nebulous/weak, with multiple low-amplitude mid-level perturbations present on the eastern periphery of upper ridging centered over Mexico and the Southwest. Still, isolated to scattered thunderstorms should develop this afternoon and evening, potentially along and south of the residual outflow boundary from the ongoing convection this morning. As low-level lapse rates become steepened through the day, isolated strong to severe gusts may occur with the more robust thunderstorms that form. Even though deep-layer shear will remain meager, modestly steepened mid-level lapse rates and cool temperatures aloft may also support occasional hail. The Marginal Risk has been adjusted for the latest guidance and observational trends, with somewhat greater confidence in convection occurring across the OK/TX Panhandles into OK along/near the outflow boundary compared to locations farther north in KS along the front. ...Upper Midwest/Great Lakes... A weak upper trough over the Upper Midwest this morning will translate slowly eastward across parts of the OH Valley and Upper Great Lakes through the period. A seasonably moist low-level airmass will remain over these areas along/south of a front, but mid-level lapse rates are expected to remain quite poor. Ongoing precipitation and cloud cover should also temper destabilization to some degree through this afternoon, with only weak MLCAPE forecast to develop. While isolated strong/gusty winds and small hail may occur with any of the stronger cores that can form later this afternoon across parts of WI into northern IL/IN and southern Lower MI, the overall severe threat appears too limited to include low severe probabilities at this time. ..Gleason/Grams.. 09/20/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0738 AM CDT Sat Sep 20 2025 Valid 201300Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTH-CENTRAL PLAINS... ...SUMMARY... Scattered strong to locally severe thunderstorms may impact parts of the south-central Plains this afternoon and evening, accompanied by an isolated threat for strong to severe wind gusts and marginally severe hail. ...South-Central Plains... A small cluster of thunderstorms across northeast OK, southwest MO, and northwest AR this morning has remained mostly sub-severe overnight owing to weak instability and deep-layer shear. Current expectations are for this activity to further weaken as it spreads eastward across AR and southern MO through mid/late morning. Outflow from these thunderstorms has surged southward across much of OK per radar imagery. Recent surface observations also show the primary front arcs from the OK Panhandle vicinity northeastward into central/eastern KS. A moist and moderately unstable airmass is forecast to exist this afternoon along/south of the front where daytime heating occurs. Large-scale ascent aloft will remain nebulous/weak, with multiple low-amplitude mid-level perturbations present on the eastern periphery of upper ridging centered over Mexico and the Southwest. Still, isolated to scattered thunderstorms should develop this afternoon and evening, potentially along and south of the residual outflow boundary from the ongoing convection this morning. As low-level lapse rates become steepened through the day, isolated strong to severe gusts may occur with the more robust thunderstorms that form. Even though deep-layer shear will remain meager, modestly steepened mid-level lapse rates and cool temperatures aloft may also support occasional hail. The Marginal Risk has been adjusted for the latest guidance and observational trends, with somewhat greater confidence in convection occurring across the OK/TX Panhandles into OK along/near the outflow boundary compared to locations farther north in KS along the front. ...Upper Midwest/Great Lakes... A weak upper trough over the Upper Midwest this morning will translate slowly eastward across parts of the OH Valley and Upper Great Lakes through the period. A seasonably moist low-level airmass will remain over these areas along/south of a front, but mid-level lapse rates are expected to remain quite poor. Ongoing precipitation and cloud cover should also temper destabilization to some degree through this afternoon, with only weak MLCAPE forecast to develop. While isolated strong/gusty winds and small hail may occur with any of the stronger cores that can form later this afternoon across parts of WI into northern IL/IN and southern Lower MI, the overall severe threat appears too limited to include low severe probabilities at this time. ..Gleason/Grams.. 09/20/2025 Read more

000
ABPZ20 KNHC 201129
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sat Sep 20 2025

For the eastern and central North Pacific east of 180 longitude:

South of the Baja California Peninsula (EP96):
Shower and thunderstorm activity remains limited in association with
an area of low pressure located a few hundred miles southwest of the
southern tip of the Baja California Peninsula. The system is
forecast to move west-northwestward into a more hostile environment
later today and tonight, where cooler waters and a drier airmass
will inhibit further development.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.

Off the Coast of Southern Mexico (EP97):
A broad area of low pressure located a couple of hundred miles south
of the southern coast of Mexico is producing a large area of
disorganized showers and thunderstorms. No development is expected
today while wind shear remains strong. However, environmental
conditions are forecast to become more conducive along the path of
the system beginning late this weekend, and a tropical depression is
likely to form early next week while it moves west-northwestward at
5 to 10 mph, roughly parallel to the coast of southern and
southwestern Mexico.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...80 percent.

$$
Forecaster Hagen

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Sat Sep 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... A complex, low-predictability upper pattern will exist next week and should eventually evolve into a closed upper low somewhere across the eastern CONUS by the end of the week. The operational ECMWF and GFS have significantly different evolution of the upper pattern, almost switching places from the solution each showed 24 hours ago. The ECMWF is now more progressive with a large cutoff low from the GFS by Wed/D5 and Thu/D6. Even the EPS and GEFS (which showed similar 500mb solutions 24 hours ago) have diverged and have lead to increasing predictability concerns. Therefore, beyond Day 4, some severe weather chances are possible within the warm sector ahead of a surface front. However, significant differences in timing and evolution of the pattern cast uncertainty on the overall threat. ...Day 4/Tuesday... As the stronger mid-level trough emerges across the Plains Monday night, a low-level jet will strengthen across Oklahoma. Therefore, a MCS will likely be ongoing at 12Z Tuesday in the Oklahoma vicinity. Moderate destabilization is forecast to the south of the remnant MCS/outflow boundary on Tuesday. This region will likely be the focus for some severe weather threat. It is unclear how the Monday/D3 convection will evolve and how that may impact Tuesday, but there is some potential for severe storms Tuesday afternoon/evening. Once the evolution of the mid-level trough and location of Monday night convection becomes more clear, severe weather probabilities may be needed. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Sat Sep 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... A complex, low-predictability upper pattern will exist next week and should eventually evolve into a closed upper low somewhere across the eastern CONUS by the end of the week. The operational ECMWF and GFS have significantly different evolution of the upper pattern, almost switching places from the solution each showed 24 hours ago. The ECMWF is now more progressive with a large cutoff low from the GFS by Wed/D5 and Thu/D6. Even the EPS and GEFS (which showed similar 500mb solutions 24 hours ago) have diverged and have lead to increasing predictability concerns. Therefore, beyond Day 4, some severe weather chances are possible within the warm sector ahead of a surface front. However, significant differences in timing and evolution of the pattern cast uncertainty on the overall threat. ...Day 4/Tuesday... As the stronger mid-level trough emerges across the Plains Monday night, a low-level jet will strengthen across Oklahoma. Therefore, a MCS will likely be ongoing at 12Z Tuesday in the Oklahoma vicinity. Moderate destabilization is forecast to the south of the remnant MCS/outflow boundary on Tuesday. This region will likely be the focus for some severe weather threat. It is unclear how the Monday/D3 convection will evolve and how that may impact Tuesday, but there is some potential for severe storms Tuesday afternoon/evening. Once the evolution of the mid-level trough and location of Monday night convection becomes more clear, severe weather probabilities may be needed. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Sat Sep 20 2025 Valid 231200Z - 281200Z ...DISCUSSION... A complex, low-predictability upper pattern will exist next week and should eventually evolve into a closed upper low somewhere across the eastern CONUS by the end of the week. The operational ECMWF and GFS have significantly different evolution of the upper pattern, almost switching places from the solution each showed 24 hours ago. The ECMWF is now more progressive with a large cutoff low from the GFS by Wed/D5 and Thu/D6. Even the EPS and GEFS (which showed similar 500mb solutions 24 hours ago) have diverged and have lead to increasing predictability concerns. Therefore, beyond Day 4, some severe weather chances are possible within the warm sector ahead of a surface front. However, significant differences in timing and evolution of the pattern cast uncertainty on the overall threat. ...Day 4/Tuesday... As the stronger mid-level trough emerges across the Plains Monday night, a low-level jet will strengthen across Oklahoma. Therefore, a MCS will likely be ongoing at 12Z Tuesday in the Oklahoma vicinity. Moderate destabilization is forecast to the south of the remnant MCS/outflow boundary on Tuesday. This region will likely be the focus for some severe weather threat. It is unclear how the Monday/D3 convection will evolve and how that may impact Tuesday, but there is some potential for severe storms Tuesday afternoon/evening. Once the evolution of the mid-level trough and location of Monday night convection becomes more clear, severe weather probabilities may be needed. Read more