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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0200 AM CDT Sat Sep 13 2025 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorm potential appears generally low on Monday. ...Synopsis and Discussion... A pair of upper troughs/lows should be in place over the northern Rockies and northern Plains Monday morning. The lead wave is forecast to advance northward from the Dakotas and MN into central Canada through the day, while the trailing low gradually opens and weakens as it moves slowly eastward over the northern Rockies/High Plains. A weak surface low should develop northward from ND into Manitoba by Monday evening, with a weak front extending southward from this low across parts of the northern/central Plains. Organized severe thunderstorm potential is currently expected to remain fairly limited, with modestly enhanced but meridional/southerly mid/upper-level flow across MN limiting deep-layer shear over the moderately unstable warm sector. Better large-scale ascent is also forecast to gradually shift northward into central Canada through the day as well. Given these potential limiting factors, low severe probabilities have not been included across northern MN and vicinity at this time. Elsewhere, general thunderstorms should occur beneath the upper low across the northern Rockies/High Plains, but both instability and deep-layer shear are forecast to remain weak across these regions. Isolated convection may also develop Monday afternoon and evening with southward extent along a surface lee trough across the southern/central Plains, but weak forcing aloft should tend to limit overall coverage. Other convection may also occur along a low-level moist axis extending from parts of the Ozarks/Mid-South northward into the Upper Midwest. ..Gleason.. 09/13/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0151 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... A mid-level trough will traverse the Plains states as a second mid-level trough progresses toward the northern Rockies tomorrow (Sunday). Upper support with the western upper trough will encourage scattered thunderstorm development across portions of the Northern Rockies. Furthermore, breezy but marginally dry surface conditions are also expected across the Great Basin. However, fuel receptiveness for wildfire spread across both regions is expected to be relatively poor, with fire weather highlights withheld. ..Squitieri.. 09/13/2025 ...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 0151 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... A mid-level trough will traverse the Plains states as a second mid-level trough progresses toward the northern Rockies tomorrow (Sunday). Upper support with the western upper trough will encourage scattered thunderstorm development across portions of the Northern Rockies. Furthermore, breezy but marginally dry surface conditions are also expected across the Great Basin. However, fuel receptiveness for wildfire spread across both regions is expected to be relatively poor, with fire weather highlights withheld. ..Squitieri.. 09/13/2025 ...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 0151 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...NO CRITICAL AREAS... ...Synopsis... A mid-level trough will traverse the Plains states as a second mid-level trough progresses toward the northern Rockies tomorrow (Sunday). Upper support with the western upper trough will encourage scattered thunderstorm development across portions of the Northern Rockies. Furthermore, breezy but marginally dry surface conditions are also expected across the Great Basin. However, fuel receptiveness for wildfire spread across both regions is expected to be relatively poor, with fire weather highlights withheld. ..Squitieri.. 09/13/2025 ...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 0150 AM CDT Sat Sep 13 2025 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... The first in a series of mid-level troughs will eject into the Plains states as a second mid-level trough impinges on the West Coast today. Seasonably moist conditions are likely across much of the Interior West, with scattered to numerous thunderstorms likely across the Rockies in association with the first upper trough. The current thinking is that primarily wetting rains may accompany most thunderstorms across the Rockies, resulting in the continued dampening of fuels. As such, no fire weather highlights have been introduced. ..Squitieri.. 09/13/2025 ...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 0150 AM CDT Sat Sep 13 2025 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... The first in a series of mid-level troughs will eject into the Plains states as a second mid-level trough impinges on the West Coast today. Seasonably moist conditions are likely across much of the Interior West, with scattered to numerous thunderstorms likely across the Rockies in association with the first upper trough. The current thinking is that primarily wetting rains may accompany most thunderstorms across the Rockies, resulting in the continued dampening of fuels. As such, no fire weather highlights have been introduced. ..Squitieri.. 09/13/2025 ...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 0150 AM CDT Sat Sep 13 2025 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... The first in a series of mid-level troughs will eject into the Plains states as a second mid-level trough impinges on the West Coast today. Seasonably moist conditions are likely across much of the Interior West, with scattered to numerous thunderstorms likely across the Rockies in association with the first upper trough. The current thinking is that primarily wetting rains may accompany most thunderstorms across the Rockies, resulting in the continued dampening of fuels. As such, no fire weather highlights have been introduced. ..Squitieri.. 09/13/2025 ...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 0150 AM CDT Sat Sep 13 2025 Valid 131200Z - 141200Z ...NO CRITICAL AREAS... ...Synopsis... The first in a series of mid-level troughs will eject into the Plains states as a second mid-level trough impinges on the West Coast today. Seasonably moist conditions are likely across much of the Interior West, with scattered to numerous thunderstorms likely across the Rockies in association with the first upper trough. The current thinking is that primarily wetting rains may accompany most thunderstorms across the Rockies, resulting in the continued dampening of fuels. As such, no fire weather highlights have been introduced. ..Squitieri.. 09/13/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

5-Day Uncertainty Track last updated Sat, 13 Sep 2025 06:00:51 GMT


Wind Speed Probabilities last updated Sat, 13 Sep 2025 06:00:51 GMT

5-Day Uncertainty Track last updated Sat, 13 Sep 2025 06:00:51 GMT


Wind Speed Probabilities last updated Sat, 13 Sep 2025 06:00:51 GMT

Issued at 1200 AM CST Sat Sep 13 2025 099 WTPZ43 KNHC 130559 TCDEP3 Remnants Of Mario Special Discussion Number 7 NWS National Hurricane Center Miami FL EP132025 1200 AM CST Sat Sep 13 2025 Recent ASCAT-C wind data and proxy-visible satellite images indicate that Mario no longer has a well-defined circulation center and has degenerated into a surface trough offshore of southwestern Mexico. Therefore, this is the final NHC advisory on the system. The remnants of Mario are forecast to become absorbed within a broader circulation to the southwest during the next couple of days. For additional information, please see High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at ocean.weather.gov/shtml/NFDHSFEPI.php FORECAST POSITIONS AND MAX WINDS INIT 13/0600Z 18.3N 105.3W 25 KT 30 MPH 12H 13/1200Z...DISSIPATED $$ Forecaster Reinhart

Issued at 0600 UTC SAT SEP 13 2025 000 FOPZ13 KNHC 130557 PWSEP3 REMNANTS OF MARIO SPECIAL WIND SPEED PROBABILITIES NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132025 0600 UTC SAT SEP 13 2025 AT 0600Z THE REMNANTS OF MARIO WERE LOCATED NEAR LATITUDE 18.3 NORTH ...LONGITUDE 105.3 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 25 KTS... 30 MPH...45 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 00Z SAT AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 00Z SAT 12Z SAT 00Z SUN 12Z SUN 00Z MON 00Z TUE 00Z WED PERIODS TO TO TO TO TO TO TO 12Z SAT 00Z SUN 12Z SUN 00Z MON 00Z TUE 00Z WED 00Z THU FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER REINHART

000
ABPZ20 KNHC 130557
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Fri Sep 12 2025

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

Active Systems:
The National Hurricane Center has issued the final advisory on the
remnants of Mario, located just offshore of the coast of
southwestern Mexico.

Central East Pacific:
An area of low pressure could develop well offshore of the coast of
southern or southwestern Mexico early next week. Environmental
conditions are expected to be conducive for gradual development
thereafter, as the low tracks westward to west-northwestward around
10 to 15 mph.
*Formation chance through 48 hours...low...near 0 percent.
*Formation chance through 7 days...low...20 percent.

South and Southeast of the Hawaiian Islands:
An area of low pressure well southeast of the Hawaiian Islands is
producing a large area of disorganized showers and thunderstorms.
Environmental conditions appear conducive for some gradual
development of this system as it moves westward or
west-northwestward at around 10 mph.
*Formation chance through 48 hours...low...near 0 percent.
*Formation chance through 7 days...low...20 percent.

$$
Forecaster Jelsema/Reinhart

Issued at 1200 AM CST Sat Sep 13 2025 000 WTPZ33 KNHC 130556 TCPEP3 BULLETIN Remnants Of Mario Special Advisory Number 7 NWS National Hurricane Center Miami FL EP132025 1200 AM CST Sat Sep 13 2025 ...MARIO IS NO LONGER A TROPICAL CYCLONE... ...THIS IS THE FINAL NHC ADVISORY... SUMMARY OF 1200 AM CST...0600 UTC...INFORMATION ----------------------------------------------- LOCATION...18.3N 105.3W ABOUT 80 MI...130 KM SW OF MANZANILLO MEXICO MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H PRESENT MOVEMENT...WNW OR 290 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 1200 AM CST (0600 UTC), the remnants of Mario were located near latitude 18.3 North, longitude 105.3 West. The remnants are moving toward the west-northwest near 14 mph (22 km/h), and this general motion is expected to continue overnight. Maximum sustained winds are near 30 mph (45 km/h) with higher gusts. The estimated minimum central pressure is 1009 mb (29.80 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: The remnants of Mario will lead to additional rainfall of 1 to 3 inches for Jalisco, with storm total amounts up to 6 inches locally through this morning. This brings a risk of flash flooding, especially in areas of higher terrain. For a complete depiction of forecast rainfall and flash flooding, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep3.shtml?rainqpf NEXT ADVISORY ------------- This is the last public advisory issued by the National Hurricane Center on this system. For additional information, please see High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on the web at ocean.weather.gov/shtml/NFDHSFEPI.php $$ Forecaster Reinhart

...MARIO IS NO LONGER A TROPICAL CYCLONE... ...THIS IS THE FINAL NHC ADVISORY... As of 12:00 AM CST Sat Sep 13 the center of Mario was located near 18.3, -105.3 with movement WNW at 14 mph. The minimum central pressure was 1009 mb with maximum sustained winds of about 30 mph.

Issued at 0600 UTC SAT SEP 13 2025 000 WTPZ23 KNHC 130555 TCMEP3 REMNANTS OF MARIO SPECIAL FORECAST/ADVISORY NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132025 0600 UTC SAT SEP 13 2025 REMNANTS OF CENTER LOCATED NEAR 18.3N 105.3W AT 13/0600Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 12 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1009 MB MAX SUSTAINED WINDS 25 KT WITH GUSTS TO 35 KT. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 18.3N 105.3W AT 13/0600Z AT 13/0000Z CENTER WAS LOCATED NEAR 17.9N 104.0W FORECAST VALID 13/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 18.3N 105.3W THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS SYSTEM. FOR ADDITIONAL INFORMATION PLEASE SEE HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFEPI AND WMO HEADER FZPN02 KWBC. $$ FORECASTER REINHART

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHERN PLAINS...EXTENDING INTO THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe storms are possible across parts of the northern Plains into the southern High Plains tomorrow (Sunday). ...Synopsis... A negatively tilted upper trough will pivot northward across the central/northern Plains, around broader cyclonic flow aloft, as a second upper trough traverses the Pacific Northwest tomorrow (Sunday). A surface low will develop and intensify while drifting northward across the Dakotas through the forecast period. Strengthening of the low will encourage the development of a southerly low-level jet, which will result in both northward moisture advection, and increased vertical wind shear, to support at least isolated severe storms across the Plains. ...Great Plains States... Widespread clouds and precipitation may be underway at the start of the period (12Z Sunday) given the warm-air advection regime in place ahead of the surface low. Through the day, some breaks in the cloud cover will support adequate insolation to generate surface-based buoyancy ahead of a confluence boundary. Surface temperatures may rise into the 70s F, amid 60+ f dewpoints, yielding 1000-2000 J/kg MLCAPE in spots. However, mid-level lapse rates are expected to be modest at best (e.g. 6-7 C/km), with the aforementioned MLCAPE constrained to tall, thin profiles. However, 20-40 kt southerly flow at 850 mb (driven by the low-level jet), overspread by 40-50 kts of south-southwesterly 500 mb flow, will yield elongated, mainly straight hodographs across the central/northern Plains. Effective bulk shear of 35-45 kts is possible from NE northward, with weaker values, but relatively more curved hodographs possible farther south into the southern High Plains. By afternoon peak heating, the rejuvenation of warm-sector convection ahead of the confluence band is likely, with scattered multicells and perhaps supercells possible from the Dakotas to the TX Panhandle. Storms will first develop across the northern Plains by early afternoon, with gradual southward development likely by early evening. Given modest lapse rates/thin CAPE profiles amid straight hodographs, the severe threat appears relatively isolated, with occasional severe gusts/hail the main threats. A tornado is possible over the northern Plains if a supercell can become sustained within the low-level jet axis and traverse a corridor of locally stronger surface-based buoyancy. The severe threat should gradually wane after dark, when surface-based buoyancy diminishes with nocturnal cooling and increased MLCINH. ..Squitieri.. 09/13/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHERN PLAINS...EXTENDING INTO THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe storms are possible across parts of the northern Plains into the southern High Plains tomorrow (Sunday). ...Synopsis... A negatively tilted upper trough will pivot northward across the central/northern Plains, around broader cyclonic flow aloft, as a second upper trough traverses the Pacific Northwest tomorrow (Sunday). A surface low will develop and intensify while drifting northward across the Dakotas through the forecast period. Strengthening of the low will encourage the development of a southerly low-level jet, which will result in both northward moisture advection, and increased vertical wind shear, to support at least isolated severe storms across the Plains. ...Great Plains States... Widespread clouds and precipitation may be underway at the start of the period (12Z Sunday) given the warm-air advection regime in place ahead of the surface low. Through the day, some breaks in the cloud cover will support adequate insolation to generate surface-based buoyancy ahead of a confluence boundary. Surface temperatures may rise into the 70s F, amid 60+ f dewpoints, yielding 1000-2000 J/kg MLCAPE in spots. However, mid-level lapse rates are expected to be modest at best (e.g. 6-7 C/km), with the aforementioned MLCAPE constrained to tall, thin profiles. However, 20-40 kt southerly flow at 850 mb (driven by the low-level jet), overspread by 40-50 kts of south-southwesterly 500 mb flow, will yield elongated, mainly straight hodographs across the central/northern Plains. Effective bulk shear of 35-45 kts is possible from NE northward, with weaker values, but relatively more curved hodographs possible farther south into the southern High Plains. By afternoon peak heating, the rejuvenation of warm-sector convection ahead of the confluence band is likely, with scattered multicells and perhaps supercells possible from the Dakotas to the TX Panhandle. Storms will first develop across the northern Plains by early afternoon, with gradual southward development likely by early evening. Given modest lapse rates/thin CAPE profiles amid straight hodographs, the severe threat appears relatively isolated, with occasional severe gusts/hail the main threats. A tornado is possible over the northern Plains if a supercell can become sustained within the low-level jet axis and traverse a corridor of locally stronger surface-based buoyancy. The severe threat should gradually wane after dark, when surface-based buoyancy diminishes with nocturnal cooling and increased MLCINH. ..Squitieri.. 09/13/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHERN PLAINS...EXTENDING INTO THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe storms are possible across parts of the northern Plains into the southern High Plains tomorrow (Sunday). ...Synopsis... A negatively tilted upper trough will pivot northward across the central/northern Plains, around broader cyclonic flow aloft, as a second upper trough traverses the Pacific Northwest tomorrow (Sunday). A surface low will develop and intensify while drifting northward across the Dakotas through the forecast period. Strengthening of the low will encourage the development of a southerly low-level jet, which will result in both northward moisture advection, and increased vertical wind shear, to support at least isolated severe storms across the Plains. ...Great Plains States... Widespread clouds and precipitation may be underway at the start of the period (12Z Sunday) given the warm-air advection regime in place ahead of the surface low. Through the day, some breaks in the cloud cover will support adequate insolation to generate surface-based buoyancy ahead of a confluence boundary. Surface temperatures may rise into the 70s F, amid 60+ f dewpoints, yielding 1000-2000 J/kg MLCAPE in spots. However, mid-level lapse rates are expected to be modest at best (e.g. 6-7 C/km), with the aforementioned MLCAPE constrained to tall, thin profiles. However, 20-40 kt southerly flow at 850 mb (driven by the low-level jet), overspread by 40-50 kts of south-southwesterly 500 mb flow, will yield elongated, mainly straight hodographs across the central/northern Plains. Effective bulk shear of 35-45 kts is possible from NE northward, with weaker values, but relatively more curved hodographs possible farther south into the southern High Plains. By afternoon peak heating, the rejuvenation of warm-sector convection ahead of the confluence band is likely, with scattered multicells and perhaps supercells possible from the Dakotas to the TX Panhandle. Storms will first develop across the northern Plains by early afternoon, with gradual southward development likely by early evening. Given modest lapse rates/thin CAPE profiles amid straight hodographs, the severe threat appears relatively isolated, with occasional severe gusts/hail the main threats. A tornado is possible over the northern Plains if a supercell can become sustained within the low-level jet axis and traverse a corridor of locally stronger surface-based buoyancy. The severe threat should gradually wane after dark, when surface-based buoyancy diminishes with nocturnal cooling and increased MLCINH. ..Squitieri.. 09/13/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Sat Sep 13 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHERN PLAINS...EXTENDING INTO THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe storms are possible across parts of the northern Plains into the southern High Plains tomorrow (Sunday). ...Synopsis... A negatively tilted upper trough will pivot northward across the central/northern Plains, around broader cyclonic flow aloft, as a second upper trough traverses the Pacific Northwest tomorrow (Sunday). A surface low will develop and intensify while drifting northward across the Dakotas through the forecast period. Strengthening of the low will encourage the development of a southerly low-level jet, which will result in both northward moisture advection, and increased vertical wind shear, to support at least isolated severe storms across the Plains. ...Great Plains States... Widespread clouds and precipitation may be underway at the start of the period (12Z Sunday) given the warm-air advection regime in place ahead of the surface low. Through the day, some breaks in the cloud cover will support adequate insolation to generate surface-based buoyancy ahead of a confluence boundary. Surface temperatures may rise into the 70s F, amid 60+ f dewpoints, yielding 1000-2000 J/kg MLCAPE in spots. However, mid-level lapse rates are expected to be modest at best (e.g. 6-7 C/km), with the aforementioned MLCAPE constrained to tall, thin profiles. However, 20-40 kt southerly flow at 850 mb (driven by the low-level jet), overspread by 40-50 kts of south-southwesterly 500 mb flow, will yield elongated, mainly straight hodographs across the central/northern Plains. Effective bulk shear of 35-45 kts is possible from NE northward, with weaker values, but relatively more curved hodographs possible farther south into the southern High Plains. By afternoon peak heating, the rejuvenation of warm-sector convection ahead of the confluence band is likely, with scattered multicells and perhaps supercells possible from the Dakotas to the TX Panhandle. Storms will first develop across the northern Plains by early afternoon, with gradual southward development likely by early evening. Given modest lapse rates/thin CAPE profiles amid straight hodographs, the severe threat appears relatively isolated, with occasional severe gusts/hail the main threats. A tornado is possible over the northern Plains if a supercell can become sustained within the low-level jet axis and traverse a corridor of locally stronger surface-based buoyancy. The severe threat should gradually wane after dark, when surface-based buoyancy diminishes with nocturnal cooling and increased MLCINH. ..Squitieri.. 09/13/2025 Read more