710
FXUS65 KRIW 022154
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
354 PM MDT SAT MAY 2 2026
KEY MESSAGES
- MOSTLY SUNNY AND WARM CONDITIONS CONTINUE TODAY, WITH HIGHS IN
THE UPPER 60S AND LOWER 70S.
- ELEVATED FIRE WEATHER CONDITIONS TODAY AND TOMORROW DUE TO VERY
DRY CONDITIONS.
- A WEAK FRONTAL BOUNDARY SWEEPS ACROSS AREAS EAST OF THE DIVIDE ON
SUNDAY, BRINGING A LOW CHANCE OF SHOWERS AND THUNDERSTORMS
(20 TO 30%) MAINLY TO HIGHER ELEVATIONS.
- THE NEXT WEATHER SYSTEM MOVES ACROSS THE STATE MONDAY AND TUESDAY,
BRINGING A BETTER OPPORTUNITY FOR RAIN AND SNOW. CONFIDENCE
REMAINS LOW IN RAINFALL AMOUNTS.
UPDATE
ISSUED AT 1244 PM MDT SAT MAY 2 2026
MINIMAL WEATHER CONCERNS TODAY AS IT REMAINS VERY DRY, WARM,
AND MOSTLY CLEAR. AN ISOLATED RAIN SHOWER IS POSSIBLE (20%) NEAR
THE MONTANA WYOMING BORDER IN THE MOUNTAINS. HUMIDITY VALUES
WILL DROP QUITE LOW THIS AFTERNOON, WITH MOST LOWER ELEVATIONS
DROPPING TO AROUND 10%. WIND WILL BE GUSTY ALONG I-25 THIS
AFTERNOON, WITH LIGHT WIND ELSEWHERE. WIND WILL REMAIN LIGHT
ENOUGH TO KEEP FIRE WEATHER CONDITIONS ELEVATED AND NOT
CRITICAL. STILL EXPECTING ISOLATED TO SCATTERED RAIN SHOWERS AND
STORMS ACROSS NORTHERN WYOMING SUNDAY AFTERNOON. CONFIDENCE
REMAINS LOW IN PRECIPITATION AMOUNTS FOR THE WEATHER SYSTEM
MONDAY THROUGH TUESDAY, BUT MODELS ARE TRYING TO HIGHLIGHT AN
AREA OF HIGHER RAINFALL AND MOUNTAIN SNOWFALL FROM THE UPPER-
GREEN RIVER BASIN TO THE WIND RIVER BASIN TO CASPER MOUNTAIN.
DOWN INTO SWEETWATER COUNTY. THERE COULD BE SOME BANDING, WITH
STRIPES OF HIGHER PRECIPITATION WHERE THOSE BANDS SET UP. IT
DOES APPEAR THAT MOST LOCATIONS WILL RECEIVE AT LEAST SOME
PRECIPITATION AND MOST HAVE A GOOD CHANCE (40-50%) OF A WETTING
RAIN.
DISCUSSION
ISSUED AT 139 AM MDT SAT MAY 2 2026
A GREAT START TO MAY CONTINUES TODAY WITH HIGH PRESSURE IN THE
REGION. SKIES REMAIN MOSTLY SUNNY, WITH ONLY A FEW HIGH CLOUDS
MOVING IN FROM THE WEST DURING THE AFTERNOON. WITH THE RIDGE
AXIS PRETTY MUCH OVERHEAD TODAY, TEMPERATURES AGAIN WILL BE WARM
FOR EARLY MAY, REACHING THE MID TO UPPER 60S WEST OF THE
DIVIDE, AND THE LOW TO MID 70S TO THE EAST.
CONDITIONS BEGIN TO CHANGE LATE TONIGHT INTO SUNDAY AS THE RIDGE
GETS SQUASHED SOUTHWARD. THIS WILL OPEN THE DOOR INITIALLY FOR
A WEAK FRONTAL BOUNDARY TO MOVE IN FROM THE NORTH SUNDAY
MORNING. WHILE THIS FRONT WON'T HAVE AN APPRECIABLE TEMPERATURE
DIFFERENCE WITH THE RIDGE STILL IN THE VICINITY, THERE WILL BE A
MARKED INCREASE IN MOISTURE, NOTED BY DEW POINT INCREASES OF 10
DEGREES AND PRECIPITABLE WATER (PW) VALUES RISING FROM 0.20 TO
ROUGHLY 0.45 BY SUNRISE SUNDAY. THIS INCREASED MOISTURE, ALONG
WITH INCREASING INSTABILITY ALOFT, WILL BRING A CHANCE FOR
SHOWERS AND THUNDERSTORMS, MAINLY ACROSS THE HIGHER ELEVATIONS
OF NORTHERN WY, INCLUDING YNP, DURING THE PEAK HEATING HOURS
SUNDAY AFTERNOON.
MONDAY AND TUESDAY WILL BE INFLUENCED BY A BROAD TROUGH TO THE
NORTHEAST BRINGING A LONG FETCH OF NORTHERLY FLOW. THIS WILL
HELP PUSH THE FRONT FARTHER SOUTH ACROSS THE REST OF THE STATE.
THE TROUGH WILL ALSO DRAW IN ENERGY FROM A CUTOFF LOW DRIFTING
ACROSS SOUTHERN CALIFORNIA, BRINGING IN MORE MOISTURE AND
INSTABILITY ACROSS THE STATE. MOST OF THE PRECIPITATION EXPECTED
WITH THIS SYSTEM STILL LOOKS TO BE AN OVERRUNNING PATTERN
BEHIND THE FRONT. STILL WATCHING MODELS TO SEE WHERE THE FRONT
FINALLY SETTLES, WHICH WILL DETERMINE WHICH AREAS TO THE NORTH
OF THE FRONT WILL BE THE FOCUS OF PRECIP MONDAY NIGHT INTO
TUESDAY. MODELS HAVE BEEN FAIRLY CONSISTENT IN THE AMOUNTS THAT
WILL BE PRODUCED (0.25 TO 0.50"), IT'S JUST GETTING THE FINAL
PLACEMENT SET.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 354 PM MDT SAT MAY 2 2026
VFR CONDITIONS THROUGH THE PERIOD AS HIGH PRESSURE IS PRESENT OVER
THE AREA. A VERY WEAK COLD FRONT MOVES THROUGH OVERNIGHT, WITH MINOR
IMPACTS TO SITES EAST OF THE CONTINENTAL DIVIDE - A LIGHT NORTH WIND
SHIFT AND INCREASING HIGHER CLOUDS. OTHERWISE, GENERALLY LIGHT WINDS
OVERNIGHT, WITH A FAIRLY TYPICAL DOWNVALLEY WIND AROUND KLND AND
KRIW.
FOR SUNDAY, GUSTY WINDS INCREASE LATE MORNING AND THROUGH THE
AFTERNOON. SOME ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE (15
TO 30 PERCENT CHANCES) FOR LOCATIONS EAST OF THE DIVIDE, WITH PROB30
GROUPS TO COVER THIS TIMING. GUSTY OUTFLOW WINDS UP TO 40 KNOTS
WOULD BE THE MAIN HAZARD. CURRENT MODELS KEEP SHOWERS NORTH OF KJAC
SO HAVE KEPT MENTION OUT FOR NOW.
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...ROWE
DISCUSSION...STRAUB
AVIATION...WITTMANN
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