526
FXUS65 KGJT 131714
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1114 AM MDT SAT SEP 13 2025
KEY MESSAGES
- SCATTERED SHOWERS AND STORMS ARE EXPECTED THIS MORNING THROUGH
THE EVENING. SOME STORMS COULD BE STRONG TO SEVERE WITH STRONG
WINDS, HAIL AND HEAVY RAINFALL POSSIBLE.
- FLASH FLOODING IS POSSIBLE ESPECIALLY OVER AREAS OF RECENT
RAINFALL WHERE SOILS ARE ALREADY SATURATED, RECENT BURN SCARS
AND AREAS OF STEEP TERRAIN.
- CONDITIONS DRY OUT ON SUNDAY SO EXPECT LESS ACTIVE WEATHER
WITH BELOW NORMAL TEMPERATURES.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 412 AM MDT SAT SEP 13 2025
THUNDERSTORMS CONTINUE TO DEVELOP EARLY THIS MORNING IN THIS
MOISTURE LADEN AND UNSTABLE AIR MASS WITH SUFFICIENT SHEAR STILL
PRESENT. WE ARE STILL MAINTAINING A SOUTHWEST FLOW WITH
SOUTHWEST TO NORTHEAST STORM MOTIONS AS THE JET REMAINS OVERHEAD
WITH THE LOW PRESSURE TROUGH JUST TO OUR WEST OVER UTAH. THE
HRRR HAS BEEN PERFORMING VERY WELL LATELY IN TERMS OF COVERAGE
AND TIMING OF CONVECTION AND THE LAST FEW RUNS HAVE BEEN
INDICATING A BIT MORE STORM COVERAGE THAN PREVIOUSLY INDICATED.
SHEAR IS A BIT LESS BUT PLENTY SUFFICIENT FOR STRONG TO SEVERE
STORMS AGAIN WITH ABOUT 30 TO 40 KTS. CAPE IS ALREADY PRESENT
WITH LITTLE TO NO CIN WHICH EXPLAINS THE ONGOING CONVECTIVE
DEVELOPMENT THIS MORNING. CAPE WILL INCREASE TO AROUND 400 TO
800 J/KG LATE THIS MORNING INTO THE AFTERNOON WITH NEAR 1000
J/KG ACROSS EASTERN UTAH. THIS IS WHERE CLEARING SKIES ARE
PRESENT SO EXPECT MORE SURFACE HEATING TO GET STORMS GOING A BIT
EARLIER. STORM MOTION WILL TRANSITION THIS AFTERNOON FROM A
SOUTHWEST TO NORTHEAST DIRECTION TO MORE OF A WEST TO EAST TRACK
AS THE NEGATIVELY TILTED TROUGH MOVES OVERHEAD. TYPICALLY ON THE
EDGE OF THE DEEP MOISTURE AND DRIER AIR TO OUR WEST, WE COULD
SEE STRONGER STORMS FORMING ALONG THIS BOUNDARY WITH THIS TROUGH
PASSAGE. WITH STORMS TODAY, STRONG GUSTY WINDS, HAIL AND HEAVY
RAINFALL ALL REMAIN POSSIBLE WITH A FEW SEVERE OR BORDERLINE
SEVERE TODAY. MUCH OF THE AREA RECEIVED SIGNIFICANT RAINFALL
YESTERDAY WITH SOME FLOODING AND DUE TO THE RECENT RAINS OVER
THE LAST COUPLE DAYS, SOILS REMAIN VERY SATURATED WHERE THIS
RAIN HAS OCCURRED. THEREFORE, THESE SATURATED AREAS REMAIN
SUSCEPTIBLE TO FLASH FLOODING AS HEAVY RAINFALL RATES ARE STILL
EXPECTED WITH STORMS TODAY. RECENT BURN SCARS AND AREAS OF STEEP
TERRAIN ARE ALSO SUSCEPTIBLE TO FLOODING. THEREFORE, EVEN THOUGH
COVERAGE WILL BE A BIT LESS THAN YESTERDAY, THE POTENTIAL IS
THERE FOR FLASH FLOODING SO DECIDED TO ISSUE A FLOOD WATCH IN
EFFECT THIS MORNING THROUGH MIDNIGHT TONIGHT.
DRIER AIR WILL MOVE IN BEHIND THE TROUGH PASSAGE TONIGHT
ALLOWING STORMS TO EXIT TO THE EAST WITH QUIETER CONDITIONS
EXPECTED OVERNIGHT. ON SUNDAY WITH THE DEEP MOISTURE AND TROUGH
TO OUR EAST, WESTERLY FLOW WILL USHER IN MUCH DRIER CONDITIONS
AND A RELATIVELY PLEASANT DAY. TEMPERATURES WILL BE MUCH COOLER
WITH FALL-LIKE READINGS AS HIGHS WILL BE AROUND 10 DEGREES BELOW
NORMAL. CANNOT RULE OUT ISOLATED STORMS SUNDAY AFTERNOON DUE TO
ANY LINGERING MOISTURE, BUT FAVORING THE HIGH TERRAIN ALONG THE
DIVIDE AS THAT WILL BE THE MAIN SOURCE OF LIFT ON SUNDAY. MOST
MODEL GUIDANCE INDICATES MUCH OF THE AREA REMAINING
PRECIPITATION FREE HOWEVER.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
ISSUED AT 334 PM MDT FRI SEP 12 2025
HIGH PRESSURE WILL BRIEFLY BUILD BEHIND THE TROUGH SUNDAY INTO
MONDAY. THIS PATTERN SHIFT WILL LEAD TO A DRIER AIRMASS MOVING
OVER THE REGION, ENDING THE ONGOING RETURN OF THE MONSOON. BY
MONDAY NIGHT A TROUGH OFF THE PACIFIC NORTHWEST WILL BE PASSING
TO OUR NORTH. AS IT PASSES, IT MAY PROVIDE JUST ENOUGH SUPPORT
TO INCREASE POPS ALONG OUR NORTHERN BORDER TUESDAY NIGHT, AND TO
ALLOW FOR AFTERNOON CONVECTION ON TUESDAY AND WEDNESDAY OVER
THE HIGHER TERRAIN. ALTHOUGH, MODELS SEEM TO DISAGREE ON BOTH
THE TIMING OF THIS THROUGH PASSAGE, AND HOW FAR SOUTH THE TROUGH
WILL DIG. IN ADDITION, MOISTURE LOOKS TO BE PRETTY LIMITED
DURING THIS PERIOD SO NOT MUCH IS EXPECTED IN TERMS OF QPF. HIGH
PRESSURE BUILDS AGAIN AFTER THIS TROUGH PASSAGE. WITH THE
DECREASE IN MOISTURE, AND PERIODS OF INCREASING HIGH PRESSURE,
SEASONABLE TEMPERATURES RETURN THROUGH THE WORKWEEK.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1104 AM MDT SAT SEP 13 2025
SCATTERED TO WIDESPREAD SHOWERS AND STORMS ARE EXPECTED THIS
AFTERNOON AND EVENING. VFR CONDITIONS WILL BE IN PLACE WITH
MVFR/IFR IN ANY SHOWER/STORM AND CIGS LOWERED TO ILS BREAKPOINTS
AT TIMES DURING CONVECTION. VFR RETURNS AFTER 06Z ALTHOUGH
CANNOT RULE OUT LOW STRATUS OR FOG DEVELOPING GIVEN RECENT
RAINFALL AND COOLER TEMPERATURES COMBINED WITH PARTIALLY
CLEARING SKIES FROM THE WEST.
HYDROLOGY
ISSUED AT 412 AM MDT SAT SEP 13 2025
SCATTERED STORMS ARE EXPECTED TO DEVELOP THIS MORNING THROUGH
THIS EVENING WITH A BIT LESS COVERAGE THAN YESTERDAY. STORMS
HAVE THE POTENTIAL TO BE STRONG TO SEVERE WITH HEAVY RAINFALL
RATES. WHILE RECENT BURN SCARS REMAIN THE MOST SUSCEPTIBLE TO
FLASH FLOODING AND DEBRIS FLOWS, MUCH OF THE CENTRAL AND
SOUTHERN AREAS OF THE CWA RECEIVED QUITE A BIT OF RAINFALL OVER
THE LAST 24 TO 36 HOURS SO SOILS REMAIN SATURATED. ANY HEAVY
RAINFALL RATES OVER RECENT SATURATED SOILS AND STEEP TERRAIN
WILL ALSO BE PRONE TO FLASH FLOODING. THEREFORE, EVEN THOUGH
COVERAGE WILL BE A BIT LESS THAN YESTERDAY, DECIDED TO ISSUE
ANOTHER FLOOD WATCH FOR THE CENTRAL AND SOUTHERN PORTIONS OF
EASTERN UTAH AND WESTERN COLORADO, INCLUDING THE RECENT BURN
SCARS.
GJT WATCHES/WARNINGS/ADVISORIES
CO...FLOOD WATCH THROUGH THIS EVENING FOR COZ003-006>014-017>023.
UT...FLOOD WATCH THROUGH THIS EVENING FOR UTZ022-027>029.
SHORT TERM...MDA
LONG TERM...GF
AVIATION...TGJT
HYDROLOGY...MDA
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