386
FXUS65 KRIW 081910
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
ISSUED BY NATIONAL WEATHER SERVICE BILLINGS MT
110 PM MDT THU MAY 8 2025
KEY MESSAGES
- A STRETCH OF WARM ABOVE NORMAL TEMPERATURES BEGINS TODAY AND
WILL PERSIST ACROSS THE COWBOY STATE INTO THE START OF NEXT
WEEK.
- A FEW ISOLATED SHOWERS WILL BE POSSIBLE MAINLY OVER HIGHER
ELEVATIONS TODAY AND FRIDAY.
- NEAR RECORD BREAKING TEMPERATURES ARE FORECAST FOR THE WEEKEND
WITH HIGHS IN THE UPPER 70S WEST OF THE DIVIDE AND LOW TO
UPPER 80S EAST OF THE DIVIDE.
UPDATE
ISSUED AT 105 PM MDT THU MAY 8 2025
PARTLY TO MOSTLY SUNNY SKIES PREVAIL ACROSS THE STATE TODAY AS
A STRETCH OF ABOVE NORMAL TEMPERATURES AND MAINLY DRY CONDITIONS
DEVELOP. A FEW ISOLATED SHOWERS CANNOT BE RULED OUT ACROSS THE
HIGHER ELEVATIONS OF NORTHERN WY THIS AFTERNOON/EVENING. THE
MAIN CONCERN WILL BE OUTFLOW WINDS PRODUCED BY ANY STORMS THAT
DO DEVELOP. HIGH TEMPERATURES TODAY AS MENTIONED EARLIER WILL
BEGIN TO CLIMB TO ABOVE NORMAL VALUES. HIGHS EAST OF THE DIVIDE
WILL RANGE FROM THE LOW TO UPPER 70S WITH LOCATIONS WEST OF THE
DIVIDE SEEING HIGHS IN THE MID TO UPPER 60S.
RIDGING BUILDS IN FOR THE END OF THE WEEK THROUGH THE WEEKEND. THIS
WILL USHER IN WELL ABOVE NORMAL TEMPERATURES WITH HIGHS IN THE LOW
70S TO LOW 80S FRIDAY. FRIDAY AFTERNOON AND EVENING WILL SEE ANOTHER
CHANCE FOR ISOLATED SHOWERS MAINLY ACROSS PORTIONS OF NATRONA AND
JOHNSON COUNTIES. WARMING CONTINUES FOR THE WEEKEND WITH LOCATIONS
EAST OF THE DIVIDE SEEING HIGHS IN THE LOW TO UPPER 80S AND MID TO
UPPER 70S WEST OF THE DIVIDE. THE WARMEST TEMPERATURES ARE EXPECTED
TO BE ACROSS THE BIGHORN BASIN WHERE HIGHS MAY NEAR OR EVEN EXCEED
90 DEGREES. LOOKING AT CLIMATE RECORDS THERE IS THE POTENTIAL FOR
SOME LOCATIONS TO SEE NEAR RECORD HIGH TEMPERATURES OVER THE
WEEKEND. THE WELL ABOVE NORMAL TEMPERATURES MAY CREATE SOME ISSUES
REGARDING SNOWMELT OF THE REMAINING HIGH ELEVATION SNOW PACK.
AS OF THURSDAY THE THREAT LOOKS MINOR WITH THE MAIN CONCERN
BEING INCREASED SMALL TRIBUTARY FLOWS WITH LARGER RIVERS LIKELY
NOT BEING OF MUCH CONCERN.
SUNDAY WILL SEE THE RIDGING GRADUALLY PUSHED EASTWARD WITH
A WEAK DISTURBANCE STARTING TO MOVE INTO THE REGION. THIS DISTURBANCE
WILL LEAD TO THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO DEVELOP
ACROSS THE STATE DURING THE AFTERNOON AND EVENING ON SUNDAY. DUE TO
THE LACK OF MOISTURE MOST OF THESE SHOWERS WILL FACE A RATHER DRY
ATMOSPHERE LEADING TO MAINLY VIRGA SHOWERS. THE OTHER CONCERN DUE TO
THIS DRYNESS WILL BE STRONG GUSTY OUTFLOW WINDS WITH ANY DEVELOPING
STORMS. TEMPERATURES BEING IN THE 70S TO 80S WITH DEW POINTS IN
THE 30S WOULD LIKELY TRANSLATE TO OUTFLOW WINDS OF 40 TO 50
MPH. MONDAY WILL SEE WARM TEMPERATURES LINGER WITH BREEZY WINDS
DEVELOPING AHEAD OF THE NEXT POTENTIAL WEATHER MAKER. CURRENTLY
THIS DISTURBANCE LOOKS TO BRING WIDESPREAD CHANCES FOR
PRECIPITATION BY THE MIDDLE OF NEXT WEEK. HOWEVER, BEING NEARLY
A WEEK OUT THERE IS STILL A LOT OF UNCERTAINTY ESPECIALLY
REGARDING THE TIMING AND TRACK OF THIS DISTURBANCE WHICH WOULD
ALTER IMPACTS FOR THE REGION.
DISCUSSION
ISSUED AT 109 AM MDT THU MAY 8 2025
THE LATEST RETURN OF SPRING CONTINUES TO BUILD ACROSS WESTERN WY
THE NEXT FEW DAYS AS H5 RIDGING BUILDS ACROSS THE INTERMOUNTAIN
WEST. H7 TEMPERATURES RANGING 5 TO 10C WILL TRANSLATE TO SFC
TEMPS IN THE 70S ACROSS THE LOWER ELEVATIONS TODAY. SINCE THE
RIDGE HASN'T YET BUILD INTO WYOMING, A WEAK SHORTWAVE WILL SWEEP
GENERALLY ACROSS NORTHWEST WY DURING THE AFTERNOON HOURS. THIS
WAVE WILL TAP SOME OF THE DAYTIME HEATING, ALLOWING SOME SHOWER
ACTIVITY TO BUILD ALONG THE HIGHEST MOUNTAIN RANGES DURING PEAK
HEATING. MOST OF THESE WILL BE SMALLER IN SIZE, SO ANY
ACCUMULATIONS WILL BE MINOR.
RIDGING BUILDS CLOSER TO WESTERN WY ON FRIDAY, BUT TEMPERATURES
WILL REMAIN SIMILAR TO THURSDAY MAINLY IN THE 70S. SIMILAR TO
TODAY, A WEAK WAVE WILL SWEEP AROUND THE EDGE OF THE RIDGE
DURING THE AFTERNOON. WITH THE RIDGE CLOSER TO WESTERN WY, IT
WILL SUPPRESS CONVECTION FOR MOST AREAS DURING PEAK HEATING, BUT
THE BIGHORNS AND AREAS DOWNWIND ACROSS JOHNSON AND NATRONA
COUNTIES WILL BE FAR ENOUGH FROM THE RIDGE TO ALLOW SOME
SHOWERS TO AGAIN BUBBLE UP DURING PEAK HEATING.
OVER THE WEEKEND, THE RIDGE FINALLY CENTERS ON WESTERN WY,
DEFLECTING ANY IMPULSES OFF TO THE NORTH. H7 TEMPERATURES JUMP
TO 10 TO 15C, SO TEMPERATURES IN THE UPPER 70S AND LOWER 80S
ARE LIKELY. SOME AREAS OF THE BIGHORN BASIN AND JOHNSON COUNTY
MAY JUMP INTO THE UPPER 80S, WITH A REMOTE 90 DEGREE READING NOT
OUT OF THE QUESTION. THIS RIDGING AND WARM TEMPERATURES ALOFT
WILL INCREASE THE THREAT FOR SNOWMELT OF THE REMAINING HIGHER
ELEVATION SNOWPACK.
EARLY NEXT WEEK FOCUSES ON THE NEXT LARGE-SCALE TROUGH COMING
ASHORE ALONG THE PACNW. LATEST MODEL RUNS SHOWING SOME IMPROVED
TAP OF MOISTURE OFF THE PACIFIC INTO WESTERN WY. MODELS ARE
STILL DIFFERING ON THE DEPTH AND SPEED OF THIS NEXT TROUGH, BUT
ARE STARTING TO INCREASE SOME OF THE RAIN CHANCES OUT WEST DUE
TO THE IMPROVED MOISTURE AVAILABILITY.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1144 AM MDT THU MAY 8 2025
VFR FLIGHT CONDITIONS ARE ANTICIPATED THIS TAF PERIOD AT ALL
TERMINALS AS HIGH PRESSURE DOMINATES THE REGION. THERE IS A 30%
CHANCE IN SHOWERS AND A FEW RUMBLES OF THUNDER AT KCOD BETWEEN
21Z-02Z. HOWEVER, BECAUSE OF THE UNCERTAINTY IN DIRECT IMPACTS
AT KCOD, WENT WITH A PROB30 AT THIS TIME. A STRAY ISOLATED
SHOWER CANNOT BE RULED OUT BETWEEN 22Z-05Z AT KRIW, KCPR, KLND,
AND KWRL BUT CHANCES (AROUND 15%) ARE TOO LOW TO INCLUDE IN TAF
AT THIS TIME. SHOULD A SHOWER DIRECTLY IMPACT A TERMINAL OR BE
IN THE VICINITY, BRIEF GUSTS UP AROUND 15-20KTS CANNOT BE RULED
OUT.
EXPECT WINDS TO INCREASE THIS AFTERNOON WITH GUSTS AROUND 20KTS AT
KRKS, KPNA, AND KBPI. OTHERWISE, WINDS SHOULD GENERALLY BE AROUND OR
LESS THAN 10KTS AT ALL OTHER TERMINALS.
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.
UPDATE...DZIEWALTOWSKI
DISCUSSION...STRAUB
AVIATION...GERHARDT
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