991
FXUS65 KRIW 252152
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
352 PM MDT MON AUG 25 2025
KEY MESSAGES
- SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS, PARTICULARLY
ALONG AND WEST OF THE CONTINENTAL DIVIDE, CONTINUE THROUGH
TUESDAY.
- A BETTER SURGE OF MOISTURE ARRIVES WEDNESDAY AND THURSDAY,
SPREADING SHOWERS AND THUNDERSTORMS ACROSS THE FORECAST AREA.
THERE IS A CHANCE OF HEAVY RAIN FOR PORTIONS OF WEST AND
SOUTHWEST WYOMING.
- TEMPERATURES COOL TO SEASONAL OR SLIGHTLY BELOW SEASONAL
AVERAGES BY WEDNESDAY, A TREND THAT CONTINUES THROUGH THE
WEEKEND. THE CHANCE OF SHOWERS AND STORMS DOES DECREASE FRIDAY
THROUGH SUNDAY, BUT SCATTERED COVERAGE REMAINS ESPECIALLY EAST
OF THE CONTINENTAL DIVIDE.
UPDATE
ISSUED AT 110 PM MDT MON AUG 25 2025
EXTENSIVE CLOUD COVER AND ISOLATED SHOWERS HAVE REMAINED OVER MAINLY
THE SOUTH HALF OF THE FORECAST AREA MONDAY MORNING. CUMULUS HAVE
BEEN DEVELOPING SINCE LATE MORNING OVER THE WIND RIVER, GROS VENTRE,
AND SOUTHERN ABSAROKA AND BIGHORN RANGES, ON THE NORTHERN FRINGE OF
THE CLOUD SHIELD. THESE AREAS SOUTHWARD WILL BE THE FOCUS OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS UNTIL SUNSET MONDAY.
THE BEST CHANCE FOR THUNDERSTORMS IS FROM 1 PM UNTIL 5 PM, MAINLY
OVER THE MOUNTAINS AND DOWNSTREAM TO THE SOUTHEAST. DYNAMICS AND
WIND FIELDS REMAIN UNFAVORABLE FOR STRONGER CONVECTION. CAMS HINT AT
LIGHT SHOWERS ACROSS THE FAR WEST OVERNIGHT, WHILE SWEETWATER COUNTY
MAY SEE A SLIGHT UPTICK AGAIN TOWARD SUNRISE TUESDAY.
ATTENTION THEN TURNS TO THE BETTER SURGE OF MOISTURE ARRIVING FROM
THE DESERT SOUTHWEST TUESDAY AND WEDNESDAY. PRECIPITABLE WATER
VALUES CLIMB TO AROUND ONE INCH OVER THE SOUTHWEST BY LATE AFTERNOON
TUESDAY, AND PUSH INTO CENTRAL WYOMING BY MIDDAY WEDNESDAY. CURRENT
MODEL TRENDS INDICATE ONLY THE FAR NORTHCENTRAL AREAS, NAMELY
JOHNSON COUNTY AND THE EASTERN BIGHORN BASIN, WOULD SEE SCATTERED OR
LESS COVERAGE BY SUNSET WEDNESDAY. NONETHELESS, THIS SURGE WILL
PROVIDE MANY AREAS WITH THE BEST CHANCE OF RAINFALL IN QUITE SOME
TIME. THE PRECIPITATION AND ASSOCIATED EXTENSIVE CLOUD COVER LEAVES
TEMPERATURES AROUND OR SLIGHTLY BELOW SEASONAL AVERAGES AFTER
MONDAY, WITH THE COOLEST IN THE FAR WEST BEGINNING WEDNESDAY.
DISCUSSION
ISSUED AT 130 AM MDT MON AUG 25 2025
WV IMAGERY CONTINUES TO SHOW THE BROAD RIDGING AND NORTHWEST
FLOW ACROSS THE CWA EXTENDING FROM A HIGH CENTERED TO THE SOUTH
OVER NEW MEXICO. IR SHOWS A SERIES OF SHORTWAVES PUSHING AROUND
THE AFOREMENTIONED HIGH PUMPING IN INCREASING MONSOONAL MOISTURE
OUT OF UTAH AND INTO WESTERN AND SOUTHERN PORTIONS OF THE STATE
AND UPPER ROCKIES. WITH THAT SAID, ONLY A COUPLE OF SCATTERED
SPOTS OF RAIN SHOWERS WEST OF THE DIVIDE AND ALONG THE I-80
CORRIDOR THAT WILL SLOWLY DIMINISH TOWARDS SUNRISE MONDAY
MORNING.
THE NEXT SHORTWAVE WILL PUSH IN FROM SOUTHEASTERN IDAHO BY EARLY
MONDAY AFTERNOON WITH HI-RES MODELS NOT IN GREAT SYNC WITH EACH
OTHER ON AGREEING WITH COVERAGE FOR AREAS WEST OF THE DIVIDE AND
FOR SOUTHERN PORTIONS OF THE STATE. SCATTERED RAIN SHOWERS AND
VERY FEW ISOLATED THUNDERSTORMS EXPECTED AS INSTABILITY FACTORS
NOT GREAT FOR MUCH ACTIVITY OF THIS SORT. REGARDLESS, ANY
ACTIVITY WILL DIMINISH TOWARDS SUNSET AND DISSIPATE BY MIDNIGHT
MONDAY NIGHT.
THE MORE ACTIVE WEATHER PATTERN WILL COME FOR TUESDAY THROUGH
THURSDAY WITH WEDNESDAY BEING THE HIGHEST QPF DAY LIKELY. THE
UPPER LEVEL RIDGE WILL BREAK DOWN EARLY TUESDAY AND MIGRATE
SOUTH AND EASTWARD ALLOWING FOR THE PAC LOW OFF THE NORTHWEST
COAST TO DEEPEN AND PUSH FURTHER SOUTH WITH INCREASED DIVERGENCE
ALOFT. THIS WILL PUSH A MULTITUDE OF SHORTWAVES THROUGH THE
UPPER ROCKIES COUPLED WITH THE AMPLY MONSOONAL MOISTURE AROUND
THE MIGRATING HIGH. THE STRONGER SHORTWAVE LOOKS TO BE WEDNESDAY
THAT WILL ALLOW FOR SOME DECENT QPF VALUES, ESPECIALLY WEST OF
THE DIVIDE TO HELP AID IN SOME OF THE ONGOING FIRES. WITH
INSTABILITY VALUES NOT OF GREAT CONCERN AND TEMPERATURES PUSHING
TO BELOW AVERAGE THIS TIME OF YEAR, THE MAJORITY OF THE
PRECIPITATION FOR THE MIDDLE OF THE WEEK WILL BE MORE SO IN THE
FORM OF RAIN SHOWERS WITH VERY FEW THUNDERSTORMS TO BE
EXPECTED. EAST OF THE DIVIDE COULD BE A WHOLE DIFFERENT STORY
PUMPING INTO BETTER VALUES, BUT THERE IS STILL SOME UNCERTAINTY
WILL MANY OF THE LONGER TERM SOLUTIONS AMONGST THE ENSEMBLE
DATA. STAY TUNED FOR UPDATES AS WE PUSH NEAR.
OTHERWISE, SEASONABLE TO EVEN JUST BELOW SEASONABLE
TEMPERATURES WILL BE HAD THROUGH THE END OF THE WEEK. A SLIGHT
WARMUP FOR THE WEEKEND AS THE MAIN UPPER LEVEL LOW PUSHES
FURTHER SOUTH ALLOW FOR SOME INDUCED RIDGING ACROSS MUCH OF THE
CWA HEADING INTO THE WEEKEND. THE NEXT MAIN SYSTEM LOOKS TO BE
MORE COLD POOL DRIVEN OUT OF CANADA AS THE MAIN PFJ EXTENDS
SOUTH INTO NORTHEASTERN PORTIONS OF THE CWA BY EARLY NEXT WEEK.
AGAIN, TIME WILL TELL THIS FAR OUT, BUT A DRYER PATTERN YET
COLDER AT THE SAME TIME POSSIBLE AFTER A FAIRLY ACTIVE UPCOMING
WORK WEEK AHEAD.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 350 PM MDT MON AUG 25 2025
MONSOONAL FLOW WILL CONTINUE TO DOMINATE THE PATTERN OVER THE
NEXT SEVERAL DAYS. VFR FLIGHT CONDITIONS WILL PREVAIL AT ALL
TERMINALS THROUGH THE PERIOD. OCCASIONAL MVFR HAZY CONDITIONS
WILL REMAIN POSSIBLE AT KBPI, KPNA, AND KLND DUE TO SMOKE FROM
NEARBY ACTIVE WILDFIRES. THIS SMOKE IS EXPECTED CONTINUE THROUGH
THE PERIOD, BUT SHOULD MIX WITH THE CLOUDS FOR MOST OF THE
PERIOD, LIMITING VSBY CONCERNS AT THE TERMINALS.
SHOWER AND THUNDERSTORM CHANCES (20 TO 30%) CONTINUE THROUGH
AROUND 04Z, PARTICULARLY WEST OF THE DIVIDE, BUT COULD CONTINUE
TO PUSH OFF OF THE WIND RIVER MOUNTAINS, IMPACTING KLND AND
POSSIBLY KRIW. GUSTY WINDS BETWEEN 18KTS TO 25KTS ARE POSSIBLE
WITH OUTFLOW BOUNDARIES FROM SHOWERS AND THUNDERSTORMS.
OTHERWISE, LIGHT WINDS (10KTS OR LESS) WILL PREVAIL THROUGH THE
PERIOD AT ALL TERMINALS. SHOWER AND THUNDERSTORM CHANCES RETURN
AROUND 18Z TUESDAY, WITH MOISTURE SPREADING EAST OF THE DIVIDE
(KLND AND KRIW TERMINALS) LATE IN THE AFTERNOON.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE
FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
AIR QUALITY ALERT UNTIL 1 PM MDT TUESDAY FOR WYZ012>016-025-
026.
UPDATE...CNJ
DISCUSSION...LOWE
AVIATION...HENSLEY
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