513
FXUS65 KGJT 011740
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1140 AM MDT SUN JUN 1 2025
KEY MESSAGES
- TEMPERATURES PEAK TODAY TEN TO 15 DEGREES ABOVE NORMAL BEFORE
COOLING GOING INTO THE WORK WEEK WITH THE SURGE MOISTURE AND
INCREASED CLOUDS.
- ISOLATED TO SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
CONTINUE ON THE HIGHER TERRAIN TODAY MOSTLY FAVORING THE
DIVIDE, WITH SOME PRODUCING GUSTY WINDS AND OCCASIONAL
LIGHTNING.
- A SURGE OF DEEP SUBTROPICAL MOISTURE ARRIVES MONDAY PRODUCING
WIDESPREAD RAINSHOWERS AND THUNDERSTORMS. LOCALIZED FLASH
FLOODING IS STILL A CONCERN.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 413 AM MDT SUN JUN 1 2025
MODELS ARE IN GOOD AGREEMENT WITH SATELLITE IMAGERY INDICATING GOOD
INITIALIZATION, AND ARE IN GOOD AGREEMENT WITH EACH OTHER FOR AT
LEAST THE FEW DAYS BOOSTING CONFIDENCE IN THEIR SOLUTIONS. THE
CUTOFF LOW OFF BAJA IS BEGINNING TO LIFT OUT TO THE NORTHEAST AND
WILL CROSS THE NORTHERN BAJA INTO THE DESERT SOUTHWEST BY MONDAY
MORNING WHILE A SHORTWAVE IS DESCENDING TOWARD THE PACIFIC NORTHWEST
AND WILL SHED ANOTHER CUTOFF LOW ALONG THE WEST COAST AS IT MOVES
INTO THE NORTHERN GREAT BASIN IN THIS SAME TIME PERIOD. THIS NEW
CUTOFF LOW WILL CONTINUE SOUTH ALONG THE COASTLINE TO OFF SOUTHERN
CALIFORNIA BY MONDAY EVENING. THE RIDGE THAT HAS BEEN SITTING IN THE
GREAT BASIN HAS SLID EAST AND IS NOW STRADDLING EASTERN UTAH AND
WESTERN COLORADO. THIS RIDGE WILL CONTINUE TO MOVE EAST AND WILL BE
WELL TO THE EAST OUT ON THE PLAINS BY MONDAY MORNING. SURFACE OBS
ARE SHOWING THE REMNANTS OF TROPICAL STORM ALVIN ARE STARTING TO
PUSH INTO THE DESERT SOUTHWEST WITH DEWPOINTS CLIMBING INTO THE MID
50'S IN SOUTHERN ARIZONA AND INTO THE 60'S TO THE SOUTH IN SONORA.
SOME MOISTURE IN THIS SOUTHERLY PUSH HAS ALREADY MADE IT UP INTO THE
REGION GENERALLY SOUTH OF THE I-70 CORRIDOR AS INDICATED BY
INCREASING CLOUDS ACROSS THESE AREAS. THE HIGH-RES MODELS HAVE
PICKED UP ON THIS, AND ARE PREDICTING AN INCREASE IN COVERAGE OF
SHOWERS AND THUNDERSTORMS FROM ISOLATED TO MORE SCATTERED THIS
AFTERNOON OVER THE HIGHER TERRAIN ALONG AND SOUTH OF THE I-70
CORRIDOR, BUT STILL FAVORING THE CONTINENTAL DIVIDE. CURRENT
PROJECTIONS HAVE THE MAIN THRUST OF MOISTURE PUSHING INTO
SOUTHEASTERN UTAH AND SOUTHWEST COLORADO EARLY MONDAY MORNING, AND
SPREADING TO THE NORTHEAST THROUGH THE DAY AS THE LOW WEAKENS INTO
AN OPEN WAVE AS IT LIFTS NORTHEAST OVER SOUTHERN COLORADO BY
EVENING. THERE ISN'T A LOT OF UPPER-LEVEL DYNAMICS TO SUPPORT STRONG
G CONVECTION, BUT THE LAPSE RATES INCREASE AS THE OPENWAVE MOVES
OVER THE REGION THROUGH THE DAY, AND WITH OROGRAPHIC LIFT, WE COULD
SEE DECENT CONVECTIVE ACTIVITY AS LONG AS THE CLOUD COVER DOESN'T
LIMIT DIURNAL HEATING TOO MUCH. BUT THEN, THAT IS STILL THE
QUESTION, "WILL THE MOISTURE PROMOTE STRATIFIED CLOUDS ACROSS THE
REGION TO PREVENT HEATING?" THAT BEING SAID, WITH PWATS AROUND AN
INCH ACROSS MUCH OF THE REGION, WPC CONTINUES TO KEEP US UNDER A
MARGINAL RISK FOR EXCESSIVE RAINFALL FOR MONDAY AND MONDAY NIGHT. IF
THE SKIES START THE DAY MORE ON THE CLEAR SIDE TO ALLOW THE HEATING,
THEN STRONGER CONVECTION IS MORE LIKELY, LEADING TO STRONGER CELLS
AND HEAVIER RAIN RATES RESULTING IN POSSIBLE FLASH FLOODING IN FLOOD-
PRONE AREAS LIKE LOCAL DRAINAGES, ARROYOS AND SLOT CANYONS. STAY
TUNED ON THIS.
WITH ALL THAT BEING SAID, TEMPERATURES WILL PEAK TODAY UNDER THE
RIDGE TEN TO 15 DEGREES ABOVE NORMAL ACROSS THE REGION WITH THE
LOWER VALLEYS REACHING INTO THE MID TO UPPER 90'S AND THE MOUNTAIN
COMMUNITIES SEEING MID 70'S TO INTO THE 80'S. WITH THE SURGE OF
MOISTURE RESULTING IN CLOUD COVER RESTRICTING DIURNAL HEATING,
TOMORROW WILL BE MUCH COOLER, RANGING FROM NEAR NORMAL ACROSS THE
NORTHERN AREAS TO TEN DEGREES BELOW NORMAL IN THE SOUTHERN
AREAS.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
ISSUED AT 121 PM MDT SAT MAY 31 2025
A CLOSED LOW PASSING TO OUR SOUTH MONDAY MORNING WILL LIFT A FRONTAL
BOUNDARY INTO THE CWA MONDAY. AS DISCUSSED HERE RECENTLY, THIS LOW
IS BRINGING ALONG A GENEROUS SUPPLY OF EXTRA-TROPICAL MOISTURE.
PWATS IN EXCESS OF 250 PERCENT OF CLIMATOLOGY ARE EXPECTED FOR
SOUTHEAST UTAH AND SOUTHWEST COLORADO. PRECIPITATION WILL LIFT
ACROSS THE CWA THROUGHOUT THE DAY MONDAY. A FEW OUTPUTS SUGGEST
24 HOUR RAINFALL TOTALS IN EXCESS OF 1 INCH. THIS REMAINS A
TRICKY FORECAST WITH TIMING AND PRECIPITATION INTENSITY. GIVEN
THE EXCESS OF MOISTURE AND THE POTENTIAL FOR HEAVY RAIN, PRETTY
MUCH THE ENTIRE CWA WILL REMAIN IN WPC'S MARGINAL RISK STATUS
FOR EXCESSIVE RAINFALL. THE BIGGEST THREAT TO FLASH FLOODING
WILL LIE IN CONVECTIVE INITIATION. A STEADY STRATIFORM RAIN
EVENT MONDAY MORNING COULD SQUASH AFTERNOON INSTABILITY PRETTY
EASILY. HOWEVER, THIS WOULD COME WITH ITS OWN UNCERTAINTY. FOR
NOW, IT WOULD BE BEST TO ASSUME A FEW CONVECTIVE
SHOWERS/THUNDERSTORMS WILL BRING LOCAL DRAINAGES, ARROYOS, SLOT
CANYONS, ETC. A RISK OF FLOODING. SOME OF THE HEAVIEST MOISTURE
WILL LIFT ACROSS THE NORTHERN MOUNTAINS MONDAY EVENING. THINGS
WILL DRY OUT WEST OF THE UT LINE BY THEN TOO THANKS TO A WEAK
BIT OF SUBSIDENCE BUILDING BACK IN OVERNIGHT. SHOWERS WILL
LIKELY HANG ON ALONG THE CONTINENTAL DIVIDE INTO TUESDAY.
ANOTHER UPPER LEVEL DISTURBANCE MOVES ACROSS THE SOUTHWEST TUESDAY.
WHILE THIS ONE PACKS LESS MOISTURE, PWATS REMAIN NEARLY 200 PERCENT
OF NORMAL AROUND THE FOUR CORNERS. SATURATED SOILS COULD CREATE SOME
ADDITIONAL HIGH WATER CONCERNS TUESDAY TOO. MODELS HOLD ONTO BROAD
CYCLONIC FLOW ACROSS THE WEST WEDNESDAY AND BEYOND. THIS SHOULD KEEP
UNSETTLED AFTERNOON CONDITIONS ALIVE NEXT WEEK. RECYCLED MOISTURE
WILL GET A LIFT FROM OROGRAPHICS EACH AFTERNOON, KEEPING SHOWERS AND
THUNDERSTORMS IN THE FORECAST EACH DAY. A DIGGING UPPER TROUGH WILL
PUSH FLOW MORE SOUTHWESTERLY BY WEEK'S END AND DRIVE TEMPERATURES
BACK UPWARD. TEMPERATURES, NEXT WEEK, WILL TREND NEAR TO BELOW
NORMAL WITH THE CLOUD COVER AND FREQUENT SHOWER ACTIVITY. CRITICAL
FIRE WEATHER REMAINS ABSENT AS WELL, THANKS TO THE SURGING RH VALUES
AND LIGHT WINDS.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1136 AM MDT SUN JUN 1 2025
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED AROUND MOUNTAIN
TERMINALS THIS AFTERNOON. GUSTY OUTFLOW WINDS, LIGHTNING, AND
BRIEF PERIODS BELOW ILS BREAKPOINTS ARE THE MAIN THREATS.
ELSEWHERE, BREEZY SOUTHWEST WINDS ARE EXPECTED FROM 18Z TO 01Z
WITH SCATTERED CLOUDS THROUGH THIS EVENING.
CEILINGS BEGIN TO LOWER AFTER 06Z FROM SOUTHWEST TO NORTHEAST
WITH SHOWERS BECOMING POSSIBLE EARLY TOMORROW MORNING AS A LOW
PRESSURE SYSTEM MOVES IN.
GJT WATCHES/WARNINGS/ADVISORIES
CO...NONE.
UT...NONE.
SHORT TERM...DB
LONG TERM...LTB
AVIATION...TGJT
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