644
FXUS65 KRIW 120403
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1003 PM MDT SAT APR 11 2026
KEY MESSAGES
- ISOLATED SHOWERS WILL LINGER OVER THE BIGHORN AND POWDER RIVER
BASINS THROUGH MIDNIGHT, AFTER WHICH TIME SKIES WILL CLEAR
FROM SOUTHWEST TO NORTHEAST DURING THE EARLY MORNING HOURS.
- SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ON SUNDAY,
THOUGH LESS WIDESPREAD THAN SATURDAY, WITH THE MOST COVERAGE
ACROSS WESTERN WYOMING.
- ELEVATED FIRE WEATHER CONDITIONS CONTINUE FOR CENTRAL WYOMING
BASINS.
- THE UNSETTLED PATTERN WILL PERSIST THROUGH NEXT WEEK, WITH
MILD AFTERNOON TEMPERATURES AND SEVERAL CHANCES FOR
PRECIPITATION. A SYSTEM LATE IN THE WEEK LOOKS TO BRING COLD
MORNING TEMPERATURES (15-25 DEGREES) TO LOWER ELEVATIONS.
UPDATE
ISSUED AT 1157 AM MDT SAT APR 11 2026
CONVECTION IS BEGINNING TO INCREASE ACROSS WESTERN AND SOUTHERN
WYOMING LATE THIS MORNING AS A SHORTWAVE ARRIVES AHEAD OF AN
APPROACHING UPPER LOW. CONTINUED DIURNAL HEATING WILL ALLOW MLCAPE
VALUES TO BUILD TO 100-500 J/KG ACROSS THE AREA, WITH SHOWERS AND
THUNDERSTORMS EXPANDING IN COVERAGE FROM WEST TO EAST OVER THE NEXT
COUPLE OF HOURS. THE MAIN CONCERN WITH THIS ACTIVITY WILL BE STRONG
OUTFLOW WIND GUSTS GIVEN THE RELATIVE DRY, WELL-MIXED BOUNDARY LAYER
(DLCAPE VALUES OF 500-1000 J/KG). THIS RISK WILL EXTEND THROUGH MID
EVENING, WITH THE LAST STORMS EXPECTED TO EXIT THE AREA BETWEEN 9 PM
AND MIDNIGHT.
DISCUSSION
ISSUED AT 145 AM MDT SAT APR 11 2026
AS AN ADVANCING TROUGH MAKES IT TO NORTHERN CALIFORNIA TODAY,
SOUTHWEST FLOW ALOFT INCREASES ACROSS WYOMING, BRINGING BETTER
MOISTURE TO THE AREA. IN ADDITION, A TROUGH IN ADVANCE OF THE MAIN
SYSTEM PASSES THROUGH TODAY. THESE FACTORS COMBINE TO BRING
INCREASED PRECIPITATION CHANCES TODAY, WITH SHOWERS BEING ABLE
TO PRODUCE RAIN THAT REACHES THE GROUND. THE MAIN PUSH OF THIS
SHORTWAVE STARTS LATE THIS MORNING, WITH SHOWER AND THUNDERSTORM
CHANCES INCREASING FROM THE SOUTHWEST THROUGH THE AFTERNOON,
AND THEN DECREASING FROM THE SOUTHWEST TO NORTHEAST BETWEEN
ABOUT 6PM AND MIDNIGHT. EVERYWHERE WILL HAVE A CHANCE FOR RAIN
TODAY (SNOW LEVELS AROUND 9000 FEET). THE BEST CHANCES WILL BE
WEST OF THE CONTINENTAL DIVIDE, WHERE THE BETTER MOISTURE WILL
BE. THE CURRENT FORECAST DEPICTS OF BLEND OF HI-RES MODELS, WITH
THE REALITY BEING THAT IT IS NEARLY IMPOSSIBLE TO DETERMINE
EXACTLY WHERE A SHOWER OR STORM COULD OCCUR TODAY, BUT THEY WILL
BE AROUND. EVERYWHERE HAS AT LEAST A 20 PERCENT CHANCE, THOUGH
ACTUAL CHANCES VARY TO BE AS HIGH AS 80 PERCENT (MAINLY WEST OF
THE DIVIDE). MANY MODELS SEEM TO DEPICT A CLUSTER OF RAIN
SHOWERS OVER SWEETWATER COUNTY THIS AFTERNOON, SO CONFIDENCE IN
RAIN IS BETTER THERE. THE MAIN HAZARD WITH ANY SHOWERS OR STORMS
WOULD BE OUTFLOW GUSTS, WHICH COULD BE UP TO ABOUT 60 MPH.
THE OTHER HAZARD TODAY WILL BE WIND, AND SOME FIRE WEATHER CONCERNS
WITH IT. MOISTURE DOES INCREASE TODAY, ESPECIALLY WEST OF THE
DIVIDE, BUT MINIMUM HUMIDITY VALUES AROUND 20 PERCENT ARE LIKELY FOR
BASINS EAST OF THE DIVIDE, DRIEST FOR JOHNSON COUNTY. IT IS ALSO
GOING TO BE WINDY TODAY, A RESULT OF A TIGHTENING PRESSURE GRADIENT.
GUSTS 25 TO 40 MPH WILL BE COMMON, AND FOR THESE DRIER PLACES, NEAR
CRITICAL FIRE WEATHER CONDITIONS COULD OCCUR.
FOR SUNDAY, PRECIPITATION CHANCES REMAIN (THOUGH MUCH MORE LIMITED
COMPARED TO TODAY), MOSTLY ALONG AND WEST OF THE DIVIDE, THOUGH SOME
"SPILL-OVER" IS LIKELY. CURRENT PROJECTED POSITIONING OF THE
INCOMING LOW WOULD FAVOR THE WESTERN MOUNTAINS (I.E. ABSAROKAS,
TETONS, YELLOWSTONE) THE MOST. GUSTY SOUTHWEST WINDS 25 TO 40 MPH
CONTINUE DURING THE DAY AS WELL, SO ELEVATED TO NEAR CRITICAL FIRE
WEATHER CONDITIONS REMAIN A CONCERN.
FOR MONDAY AND TUESDAY, THE MODEL TREND CONTINUES TO BE FOR A WEAKER
AND DRIER SYSTEM, UNFORTUNATE NEWS FOR THOSE WISHING FOR
PRECIPITATION. LIQUID TOTALS HAVE DROPPED ONCE AGAIN, WITH VERY
LIMITED CHANCES FOR LOW ELEVATION BASIN LOCATIONS. ELEVATED TO NEAR
CRITICAL FIRE WEATHER LOOKS TO CONTINUE AS WELL AS GUSTY WINDS OCCUR.
LOOKING FURTHER AHEAD, THERE IS GROWING CONFIDENCE IN A COLDER SYSTEM
TOWARDS THE END OF NEXT WEEK (THURSDAY-SATURDAY). THIS SYSTEM HAS
THE POTENTIAL TO BRING MORNING LOW TEMPERATURES IN THE LOW 20S, WITH
MULTIPLE MORNINGS IN A ROW UNDER 30 DEGREES. THIS IS A HEADS UP TO
THOSE WITH SPRINKLERS OR VULNERABLE VEGETATION.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 955 PM MDT SAT APR 11 2026
VFR CONDITIONS EXPECTED FOR MOST LOCATIONS OVER THE NEXT 24
HOURS. SKIES WILL BE CLEARING ACROSS THE REGION OVERNIGHT, FIRST
WITH THE SOUTHWESTERN QUADRANT OF THE STATE, THEN MOVING
NORTHEASTWARD. WINDS BECOME LIGHT OVERNIGHT, ALTHOUGH KCOD
COULD SEE OCCASIONAL WESTERLY GUSTS MIX DOWN FROM THE MID
LAYERS. POSSIBLE MVFR CEILINGS MENTIONED IN THE PREVIOUS
DISCUSSION NOW LOOK VERY UNLIKELY WITH THE LATEST HIGH
RESOLUTION MODEL RUNS.
LATE SUNDAY MORNING INTO THE AFTERNOON, WINDS WILL BECOME BREEZY
AND GUSTY STATEWIDE, WITH 25 TO 35 KT GUSTS BECOMING COMMON.
TERMINALS WEST OF THE CONTINENTAL DIVIDE WILL HAVE SEVERAL
HOURS WHERE ISOLATED SHOWERS COULD IMPACT VISIBILITY BRIEFLY,
WITH KJAC LOOKING LIKE THE MOST LIKELY LOCATION TO BE AFFECTED
BY AN OCCASIONAL SHOWER. WINDS DECREASE SHORTLY AFTER SUNSET
SUNDAY EVENING.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...MYERS
DISCUSSION...WITTMANN
AVIATION...VANDENBOOGART
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