584
FXUS65 KRIW 192230
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
330 PM MST THU DEC 19 2024
KEY MESSAGES
- WINDS DIMINISH TODAY, WITH QUIET WEATHER AND UNSEASONABLY WARM
TEMPERATURES THROUGH SATURDAY UNDER BUILDING HIGH PRESSURE.
- WEAK SHORTWAVE THIS WEEKEND COULD BRING LIGHT SNOW TO THE WEST (90%
CHANCE OF LESS THAN 4 INCHES OF SNOW FOR HIGHEST FAVORED
PEAKS) AND A GUSTY WIND EAST OF THE DIVIDE.
- RELATIVELY QUIET THROUGH CHRISTMAS WITH PERSISTENT RIDGING,
DESPITE A FEW WEAK SHORTWAVES.
DISCUSSION
ISSUED AT 1238 PM MST THU DEC 19 2024
NOW THAT WE ARE ALL STANDING UPRIGHT AGAIN, WINDS WILL CONTINUE TO
DIMINISH THROUGH THE DAY TODAY WITH LIGHT WINDS (LESS THAN 15 MPH)
EXPECTED FOR MOST LOCATIONS BY SUNSET THIS EVENING. THE BIGGEST
HOLDOUT ON DECREASING WINDS HAS BEEN THE BUFFALO AREA, WITH GUSTS
REMAINING 20 TO 30 MPH INTO THE EARLY PART OF THE AFTERNOON, BUT
THEY TOO WILL SEE DECREASING WINDS BY THE LATER PART OF THE
AFTERNOON WITH MOSTLY LIGHT WINDS BY SUNSET. RIDGING BUILDS TODAY
AND WINDS WILL THUS REMAIN LIGHT THROUGH SATURDAY.
WITH BUILDING HIGH PRESSURE, WHILE WINDS ARE ON THE DECREASE,
TEMPERATURES WILL BE ON THE RISE. HIGH TEMPERATURES TOMORROW WILL BE
15 TO 20 DEGREES ABOVE NORMAL FOR MOST AREAS. BY SATURDAY,
TEMPERATURES 20 DEGREES OR MORE ABOVE NORMAL WILL SPREAD ACROSS MUCH
OF THE BIGHORN BASIN, JOHNSON AND NATRONA COUNTIES, AND ACROSS THE
WESTERN MOUNTAINS, WITH MOST OTHER AREAS SEEING TEMPERATURES 15
DEGREES ABOVE NORMAL. WHAT EXACTLY IS NORMAL? "NORMAL" HIGHS FOR MID-
DECEMBER ARE GENERALLY IN THE LOW TO MID 30S FOR MOST POINTS EAST OF
THE DIVIDE, AND UPPER 20S WEST OF THE DIVIDE. WITH TEMPERATURES 20
DEGREES ABOVE NORMAL, THAT MEANS PLACES LIKE BUFFALO AND CASPER WILL
SEE TEMPS IN THE MID 50S, EVEN APPROACHING 60F SATURDAY
AFTERNOON, WHILE WESTERN VALLEYS WILL SEE TEMPS IN THE UPPER 30S
TO NEAR 40F.
SUNDAY WILL SEE A SLIGHT DIP IN TEMPERATURES AS A SHORTWAVE SLIDES
THROUGH AND TEMPERATURES REMAIN MUCH ABOVE NORMAL THROUGH AT
LEAST CHRISTMAS EVE (TUESDAY). THE AFOREMENTIONED SHORTWAVE
WILL BE QUICK-MOVING AND WILL BRING LIMITED IMPACTS. WINDS WILL
TICK UP SATURDAY NIGHT AS THE SHORTWAVE APPROACHES, WITH A 20%
CHANCE OF HIGH WIND FOR FAVORED AREAS SUCH AS OUTER DRIVE (ON
THE SOUTH SIDE OF CASPER) AND SOUTH PASS/RED CANYON. WEST OF THE
DIVIDE, SOME SNOW SHOWERS LOOK POSSIBLE (50%) CHANCE, BUT
AMOUNTS WILL BE MINIMAL, WITH 90TH PERCENTILE AMOUNTS FOR
HIGHEST PEAKS AROUND 4 TO 6 INCHES. SNOW/WIND IMPACTS WILL BE
LATE SATURDAY NIGHT THROUGH SUNDAY MORNING WITH BOTH WIND AND
SNOW TAPERING OFF BY SUNDAY AFTERNOON.
RIDGING WILL REMAIN THE PRIMARY PATTERN THROUGH MID NEXT WEEK,
REDUCING OUR CHANCES OF A WHITE CHRISTMAS TO NEAR ZERO. THAT BEING
SAID, THERE DOES LOOK TO BE ANOTHER WEAK SHORTWAVE MONDAY NIGHT,
WITH AGAIN, VERY LIMITED IMPACTS (SIMILAR TO OR LESS THAN SATURDAY
NIGHT/SUNDAY). THERE ARE HINTS AT A SOMEWHAT MORE POTENT TROUGH FOR
CHRISTMAS DAY (WEDNESDAY), HOWEVER, MODELS ARE STILL STRUGGLING TO
COME INTO AGREEMENT ON TRACK OF THE LOW CENTER. THUS, IT IS NOT
POSSIBLE TO PROVIDE ANY DETAILS OR INFO REGARDING SNOW CHANCES OR
TRAVEL IMPACTS AT THIS TIME. THE CHRISTMAS DAY STORM DOES HOWEVER
APPEAR TO POSSIBLY KICK US INTO A TROUGHIER PATTERN, AT LEAST
TEMPORARILY, SO FOR THOSE HOPING FOR SNOW, THIS COULD BE A GLIMMER
OF HOPE TO HOLD ONTO AS WE MOVE INTO LATE DECEMBER.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 330 PM MST THU DEC 19 2024
AS A RIDGE MOVES OVERHEAD SKIES WILL REMAIN MOSTLY CLEAR, WITH VFR
CONDITIONS PERSISTING THROUGH THE TAF PERIOD. WIND WILL INCREASE
THIS EVENING AT KCPR, SUSTAINED AROUND 10 KNOTS OVERNIGHT,
INCREASING BY 15Z/FRI. WIND WILL REMAIN LIGHT (BELOW 10 KNOTS) AT
ALL OTHER TERMINALS FOR THE NEXT 24 HOURS.
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...HENSLEY
AVIATION...ROWE
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