153
FXUS65 KGJT 201737
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1037 AM MST MON JAN 20 2025
KEY MESSAGES
- A WEAK DISTURBANCE IN NORTHWEST FLOW WILL BRING ADDITIONAL
LIGHT SNOW ACCUMULATIONS THROUGH THIS AFTERNOON.
- CLEARING THIS EVENING IS EXPECTED TO BRING MARKEDLY COLDER
TEMPERATURES TO THE REGION TONIGHT INTO TUESDAY MORNING, IN
ADDITION TO VERY COLD WIND CHILL READINGS. SO COLD IN FACT,
THAT AN EXTREME COLD WEATHER WARNING IS IN EFFECT FOR THE
MOUNTAINS AND HIGH VALLEYS OF WESTERN COLORADO. ALSO, A COLD
WEATHER ADVISORY IS IN EFFECT FOR SOME LOWER VALLEY AREAS DUE
TO VERY COLD WIND CHILLS.
- TEMPERATURES FINALLY BEGIN TO MODERATE DURING THE LATTER HALF
OF THE WEEK.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 320 AM MST MON JAN 20 2025
LIGHT SNOW IS ONGOING ACROSS THE MOUNTAINS AND HIGHER VALLEY
AREAS THIS MORNING AS A WEAK SHORTWAVE TROUGH MOVES THROUGH THE
AREA. THE ARCTIC AIR MASS REMAINS IN PLACE, WHICH COMBINED WITH
WEAK OROGRAPHICS AND STEEP LAPSE RATES IS RESULTING IN CONTINUED
LIGHT SNOW. ACCUMULATIONS ARE VERY MINIMAL AS THIS ARCTIC AIR
MASS IS DEVOID OF MOISTURE SO ONLY EXPECTING ANOTHER 1 TO 3
INCHES AT BEST OVER THE MOUNTAINS. THE INCREASED CLOUD COVER AS
A RESULT IS ALLOWING TEMPERATURES TO STAY A BIT MILDER THAN LAST
NIGHT...BUT STILL COLD, JUST NOT AS COLD. FOR COMPARISON, LOW
SO FAR IN GUNNISON THIS MORNING OF -11F VERSUS -28F YESTERDAY
MORNING! OR 5F SO FAR IN CRAIG THIS MORNING VERSUS -22F
YESTERDAY MORNING! SHOWERS LOOK TO LAST THROUGH EARLY AFTERNOON
OVER THE CENTRAL AND SOUTHERN MOUNTAINS BEFORE COMING TO AN END
BY LATE AFTERNOON AS CLEARING SKIES WORK IN FROM THE NORTH ON
THE BACK EDGE OF THIS LARGE ARCTIC TROUGH.
TONIGHT IS EXPECTED TO BE THE COLDEST NIGHT OF THE YEAR AS
CLEARING SKIES AND AN ARCTIC AIR MASS STILL IN PLACE RESULTS IN
STRONG EFFICIENT RADIATIONAL COOLING AND TEMPERATURES BOTTOMING
OUT WELL BELOW ZERO IN THE MOUNTAINS AND HIGH VALLEYS. EVEN
THOUGH WINDS WILL BE LIGHT, IT WILL BE ENOUGH OF A FACTOR TO
RESULT IN EXTREME WIND CHILLS TO MUCH OF THE AREA. THE MOUNTAINS
AND HIGH VALLEYS ARE EXPECTED TO SEE WIND CHILL READINGS OF AT
LEAST -35F WHILE SOME LOWER VALLEYS SEE WIND CHILL READINGS
TONIGHT IN THE -15F TO -25F DEPENDING ON WHICH AREA...IT IS
COLDER/LOWER THE HIGHER YOU GO. AS A RESULT, UPGRADED THE
EXTREME COLD WATCH TO AN EXTREME COLD WARNING FOR THE MOUNTAIN
AREAS AND HIGH VALLEYS INCLUDING THE CENTRAL YAMPA RIVER BASIN,
UPPER YAMPA RIVER BASIN AND GUNNISON BASIN. BASED ON COLD
ADVISORY WIND CHILL CRITERIA BEING MET IN SOME LOWER VALLEYS,
DECIDED TO ADD THE REMAINING WESTERN COLORADO VALLEYS TO A COLD
WEATHER ADVISORY FROM 9 PM TONIGHT UNTIL 9 AM TUESDAY MORNING.
THE ONLY AREAS THAT ARE NOT INCLUDED ARE THE GRAND VALLEY AND
PARADOX VALLEY AS WIND CHILLS LOOK TO REMAIN UNDER THE -15F
CRITERIA NEEDED FOR A COLD WEATHER ADVISORY.
TEMPERATURES TODAY AND TONIGHT ARE EXPECTED TO BE BETWEEN 15 AND
25 DEGREES BELOW NORMAL VALUES FOR THIS TIME OF YEAR. WE ARE
ANTICIPATING TEMPERATURES TO MODERATE SOME ON TUESDAY AFTERNOON
WITH HIGHS BETWEEN 10 AND 15 DEGREES BELOW NORMAL. THE GUNNISON
BASIN STILL WILL REMAIN THE EXCEPTION EVEN AFTER THIS ARCTIC AIR
MASS DEPARTS DUE TO STRONG INVERSIONS DUE TO EXISTING DEEP SNOW
PACK WITH HIGHS TUESDAY AROUND 25 DEGREES BELOW NORMAL. DRY
WEATHER IS EXPECTED TUESDAY WITH MOSTLY SUNNY SKIES TO START THE
DAY AS HIGH PRESSURE OVER THE DESERT SOUTHWEST HELPS PUSH THIS
ARCTIC AIR MASS AND ASSOCIATED TROUGH EASTWARD BY AFTERNOON. A
WEAK SHORTWAVE MOVING ACROSS THE NORTHERN ROCKIES COULD ALLOW
FOR SOME INCREASED HIGH CLOUD COVER DURING THE AFTERNOON BUT NO
PRECIPITATION EXPECTED.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 320 AM MST MON JAN 20 2025
UPPER-LEVEL FLOW WILL BECOME MORE NORTHERLY ON WEDNESDAY ON THE
LEADING EDGE OF A BUILDING TROUGH IN THE PACIFIC, DRIVING
SEASONALLY CHILLY TEMPERATURES THROUGH THE INTERMOUNTAIN WEST.
WHILE IT WON'T BE ANYTHING LIKE THE EXTREME COLD WE SAW OVER
THIS PAST WEEKEND, IT WILL STALL OUT THE WARM-UP A LITTLE LONGER
AND KEEP TEMPERATURES 5 TO 10 DEGREES BELOW NORMAL. TO FOLLOW
THIS, ENSEMBLES ARE IN REASONABLE AGREEMENT NOW THAT A SHORTWAVE
TROUGH WILL FORM AROUND BRITISH COLUMBIA AND MIGRATE SOUTHWARDS
ACROSS THE WEST COAST LATE THIS WEEK. CORRESPONDING WITH THIS,
FLOW WILL FINALLY SHIFT TO A MORE ZONAL PATTERN ON FRIDAY BEFORE
BECOMING SOUTHWESTERLY OVER THE WEEKEND. THIS LOOKS TO BE OUR
SIGH OF RELIEF FROM THIS COLD SPELL AS TEMPERATURES SHOULD RISE
TO NEAR OR ABOVE NORMAL VALUES.
IT BECOMES DIFFICULT TO TELL WHAT HAPPENS NEXT THOUGH, BUT
CLUSTER ANALYSIS SHOWS DECENT CONFIDENCE IN THE MODERATE-TO-
STRONG NATURE OF THIS LOW, WHICH COULD BRING ACTIVE WEATHER
ACROSS THE SOUTHWESTERN CONUS. POTENTIAL IMPACTS FROM THIS
SYSTEM FOR OUR REGION INCLUDE MODERATE MOISTURE TRANSPORT LATE
IN THE WEEKEND, WHICH COULD ULTIMATELY BE OUR NEXT SHOT AT
NOTABLE PRECIPITATION. THOUGH, CURRENT IVT FORECASTS INDICATE
THE STRONGEST ADVECTION OF MOISTURE TO FALL WELL TO OUR SOUTH.
OF COURSE, THIS IS GETTING FAR OUT IN THE LONG TERM, SO DETAILS
ON TIMING, LOCATION, AND MAGNITUDE OF THIS LOW PRESSURE SYSTEM
ARE ALL SPECULATIVE AT THE MOMENT.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1037 AM MST MON JAN 20 2025
CONDITIONS RAPIDLY IMPROVED IN THE LATE MORNING AS SUBSIDENCE
ALOFT BROUGHT CLEARING AND DECREASED SNOW SHOWERS. HOWEVER, AT
KASE CEILINGS BELOW ILS BREAKPOINTS LINGERED, BUT SHOULD CLEAR
UP BY 20Z. FARTHER SOUTH, KTEX WAS ALSO EXPERIENCING SOME LOWER
CEILINGS AND THE POTENTIAL FOR AN EARLY AFTERNOON SNOW SHOWER.
ELSEWHERE, AND BEYOND 20Z, VFR CONDITIONS TAKE OVER, THOUGH
BRISK NORTH AND NORTHWEST WINDS WILL IMPACT A NUMBER OF
AIRFIELDS ACROSS THE REGION.
GJT WATCHES/WARNINGS/ADVISORIES
CO...COLD WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM MST
TUESDAY FOR COZ001-007-008-011-021>023.
EXTREME COLD WARNING FROM 6 PM THIS EVENING TO 11 AM MST
TUESDAY FOR COZ002-004-005-009-010-012>014-018-019.
UT...NONE.
SHORT TERM...MDA
LONG TERM...BW
AVIATION...NL
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