144
FXUS65 KRIW 211852
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1152 AM MST SAT DEC 21 2024
KEY MESSAGES
- NEAR RECORD HIGH TEMPERATURES FOR PARTS OF CENTRAL WYOMING
AGAIN TODAY.
- DUAL SHORTWAVE TROUGHS BRING MORE SNOWFALL TO THE WESTERN
MOUNTAINS THIS WEEKEND INTO EARLY NEXT WEEK.
- I'M DREAMING OF A TAN CHRISTMAS. SAID NO ONE EVER.
DISCUSSION
ISSUED AT 140 AM MST SAT DEC 21 2024
NOT MUCH CHANGE IN THE ONGOING FORECAST THROUGH THE NEXT WEEK,
WITH MODELS AGREEING ON QUICKLY MOVING ZONAL FLOW BRINGING BRIEF
WAVES THROUGH THE AREA EVERY COUPLE DAYS, WHILE HOLDING BACK THE
COLD TEMPERATURES FOR THE FORESEEABLE FUTURE...
RIDING CONTINUES TO BRING WESTERLY FLOW TO THE REGION, CAUSING
DOWNSLOPING WARMING TO AREAS EAST OF THE DIVIDE. THIS WILL BRING
NEAR RECORD TEMPERATURES TO AREAS ALONG THE I-25 CORRIDOR AND
THE BIGHORN BASIN, WITH HIGHS IN THE 50S TO NEAR 60! ON THE
SHORTEST DAY OF THE YEAR. IN WYOMING. AREAS WEST OF THE DIVIDE
WILL STILL REACH INTO THE 30S, BUT THE SNOW PACK IN THOSE AREAS
WILL KEEP TEMPS IN CHECK FOR THE WEEKEND.
THE NEXT TWO SHORTWAVES SWEEP ACROSS NORTHERN WYOMING SATURDAY
NIGHT AND AGAIN SUNDAY NIGHT, BRINGING A BRIEF PUSH OF
PRECIPITATION INTO THE WESTERN MOUNTAINS. THE WESTERLY FLOW AND
BRIEF MOISTURE TAP FROM THE PACIFIC WILL CAUSE OROGRAPHIC LIFT
FOR SNOWFALL. BEST PEAK SNOWFALL RATES WILL BE WHEN THE WAVES
PASS BY SATURDAY NIGHT AND SUNDAY NIGHT, BUT OVERALL WEAKNESS OF
THESE SYSTEM WILL KEEP SNOW RATES LOW THROUGH THE PERIOD.
CURRENT FORECAST SNOWFALL ACCUMULATIONS WILL GENERALLY REACH 6
TO 8 INCHES FOR THE TETONS AND 3 TO 6 INCHES FOR THE SALTS AND
WYOMINGS BY MONDAY EVENING. THE FIRST TROUGH SATURDAY NIGHT
STILL LOOKS TO HAVE A HIGH WIND COMPONENT WITH AN ADJACENT JET
STREAK MOVING THROUGH. MODELS HAVE BACKED OFF A BIT ON THE
STRENGTH OF THE WINDS, BUT THE MAIN FOCUS OF THE GUSTY WINDS
WILL BE ACROSS CENTRAL WY FROM SOUTH PASS TOWARD CASPER.
ANOTHER BRIEF LULL COMES THROUGH TUESDAY BEFORE THE NEXT TROUGH
MOVES ACROSS THE CENTRAL ROCKIES CHRISTMAS MORNING. THE MAIN
CORE OF THIS SYSTEM GOES SOUTH INTO COLORADO, SO SNOWFALL WILL
BE LIMITED TO ANY MOISTURE THAT CAN BE SQUEEZED OUT BY
OROGRAPHIC LIFT, LIMITING NEW SNOW TO THE HIGHER ELEVATIONS,
WITH TOTAL ACCUMULATIONS STAYING UNDER 2 INCHES. IN ESSENCE, IF
YOU CURRENTLY HAVE SNOW ON THE GROUND NOW, CONGRATULATIONS, YOU
SHOULD WAKE UP TO A WHITE CHRISTMAS. IF YOU DON'T HAVE SNOW
CURRENTLY, YOU WON'T HAVE WHITE ON THE GROUND FOR CHRISTMAS
MORNING.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1151 AM MST SAT DEC 21 2024
FOG SHOULD CONTINUE TO DISSIPATE AT KJAC OVER THE NEXT HOUR OR SO,
LEAVING ALL TERMINALS VFR THROUGH THE DAY. AN APPROACHING SHORTWAVE
TROUGH WILL BREAK DOWN THE RIDGE AND RETURN SNOW CHANCES TO WESTERN
WYOMING. KJAC WILL BEGIN TO SEE IMPACTS AS EARLY AS 04Z IF HI-RES
GUIDANCE IS TO BE TRUSTED, BUT IS MORE LIKELY AFTER 10Z. CONFIDENCE
IS NOT PARTICULARLY HIGH ON THIS, HOWEVER, AS MOST OF THE SNOW
SHOULD REMAIN OVER THE MOUNTAINS. STILL, AT LEAST MVFR CEILINGS LOOK
PROBABLE AT KJAC THROUGH SUNDAY MORNING. OTHER TERMINALS WILL REMAIN
VFR THOUGH WITH LOWERING CEILINGS AT KBPI AND KPNA. KCPR WILL BE
GUSTY THROUGH THE PERIOD.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING, AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...STRAUB
AVIATION...MYERS
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