383
FXUS65 KRIW 261822
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1222 PM MDT SUN JUL 26 2026
KEY MESSAGES
- ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS BECOME
MORE COMMON BETWEEN BY 2 PM SUNDAY. THE BEST CHANCE FOR THE
SHOWERS AND STORMS REMAINS OVER THE NORTH-HALF OF THE STATE
WHERE A FEW STORMS COULD BE STRONG (WIND GUSTS AROUND 50 MPH).
- SUNDAY STAYS UNSEASONABLY HOT WITH DAYTIME HIGHS IN THE 90S TO
LOWER 100S. A HEAT ADVISORY CONTINUES THROUGH 9 PM SUNDAY FOR
LOWER ELEVATIONS EAST OF THE CONTINENTAL DIVIDE.
- MOISTURE FROM THE SOUTHWEST CONTINUES TO STREAM NORTHWARD INTO
WYOMING THROUGH AT LEAST WEDNESDAY, ALLOWING FOR LITTLE
CHANGE IN THE CADENCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. TEMPERATURES REMAIN ABOVE NORMAL.
UPDATE
ISSUED AT 1222 PM MDT SUN JUL 26 2026
MOISTURE CONTINUES TO SPREAD NORTHWARD ACROSS WYOMING AS IT
ROTATES AROUND HIGH PRESSURE ANCHORED OVER THE SOUTHERN ROCKIES.
THERE IS LITTLE, IF ANY, CHANGE IN THIS PATTERN OVER THE NEXT
SEVERAL DAYS. A SHORTWAVE WITHIN THIS SOUTHWEST FLOW ALOFT WILL
TRACK ACROSS SOUTHERN MONTANA SUNDAY AFTERNOON AND EVENING.
SCATTERED SHOWERS AND THUNDERSTORMS ERUPT ACROSS MAINLY NORTHERN
WYOMING BY 2 PM SUNDAY AND PROGRESS EAST THROUGH THE AFTERNOON.
MANY LOCATIONS WILL SEE A DOWNTURN IN CONVECTIVE COVERAGE BY 7
PM SUNDAY, WHILE LOCATIONS OVER NORTH-CENTRAL WYOMING SEE THE
CONVECTION LINGER UNTIL 9-10 PM SUNDAY. LATEST 18Z KRIW SOUNDING
SHOWS 0.81" OF PRECIPITABLE WATER, WELL-ABOVE AVERAGE, BUT MUCH
OF IT IS CONCENTRATED ABOVE 550MB. THEREFORE, AS WE SAW
SATURDAY, BRIEF DOWNPOURS ARE POSSIBLE WITH THE THUNDERSTORMS.
HOWEVER, AGAIN GIVEN HIGH-BASED CONVECTION AND A DRY SUB-CLOUD
LAYER, THE PRIMARY HAZARD WILL BE GUSTY OUTFLOW WIND 40 TO 50
MPH. SPC HAS OUR NORTHERN-TIER OF COUNTIES HIGHLIGHTED WITHIN A
MARGINAL RISK FOR SEVERE WIND GUSTS. A SECONDARY SHORTWAVE WORKS
ITS WAY NORTH FROM UTAH SUNDAY EVENING AND OVERNIGHT LEADING TO
INTERMITTENT LIGHT SHOWERS ACROSS THE FAR SOUTH AND EVENTUALLY
WESTERN PORTIONS OF THE FORECAST AREA THROUGH SUNRISE MONDAY.
INCREASED MID/HIGH-LEVEL CLOUD COVER ASSOCIATED WITH THIS WAVE
SHOULD HELP DROP MONDAY HIGHS A FEW DEGREES, WHILE POSSIBLY
DELAYING THE ONSET OF SCATTERED SHOWERS AND THUNDERSTORMS UNTIL
CLOSER TO MID-AFTERNOON MONDAY.
DISCUSSION
ISSUED AT 249 AM MDT SUN JUL 26 2026
THE OVERALL PATTERN ACROSS THE WESTERN US REMAINS RELATIVELY
UNCHANGED TODAY, WITH THE H5 RIDGE CENTERED OVER THE FOUR
CORNERS, AND WY ALONG THE NORTHERN PERIPHERY OF THE RIDGE. ABOVE
NORMAL TEMPERATURES REMAIN IN PLACE ACROSS THE STATE UNDER THE
RIDGE, WITH RECORD TO NEAR-RECORD HIGHS AGAIN EXPECTED TODAY.
THE HEAT ADVISORY REMAINS IN PLACE FOR THE LOWER ELEVATIONS OF
CENTRAL AND NORTHERN WY FOR THE CONTINUED HEAT AND THE VERY WARM
OVERNIGHT TEMPERATURES. MONSOON MOISTURE CONTINUES TO WRAP
AROUND THE NORTHERN EDGE OF THE RIDGE INTO NW WY, WHICH WILL
BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. STORMS AGAIN
WILL INITIALLY FORM ON THE HIGHER ELEVATIONS OF WESTERN
MOUNTAINS AND MOVE TO THE NORTHEAST. STORMS WILL HAVE GOOD
FORWARD MOTION AGAIN, SO THIS WILL MINIMIZE THE OVERALL FLOODING
THREAT. STRONG INVERTED-V PROFILE INDICATES MAIN THUNDERSTORM
THREAT WILL BE GUSTY WINDS, POSSIBLY GUSTING ABOVE 50 MPH,
ESPECIALLY ACROSS NORTHERN WY WHERE THE T-TD SPREAD WILL BE
GREATEST.
LONGER TERM MODELS SHOW NEARLY NO CHANGE IN THIS PATTERN THE
ENTIRE WEEK, WITH THE H5 RIDGE HOLDING FAST ACROSS THE SOUTHERN
ROCKIES. THIS WILL KEEP THE HEAT IN PLACE, WITH THE DAYTIME
THUNDERSTORMS EACH AFTERNOON FOR NW WY. AN EMBEDDED SHORTWAVE
RACES AROUND THE NORTHERN EDGE OF THE RIDGE ON WEDNESDAY, WHICH
COULD BRING AN ENHANCEMENT OF THE THUNDERSTORMS FOR MORE OF THE
STATE.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1114 AM MDT SUN JUL 26 2026
SATELLITE IMAGERY SHOWS CUMULUS DEVELOPING OVER THE SOUTHWEST AND
NORTHERN MOUNTAINS LATE SUNDAY MORNING, WHILE A SHORTWAVE APPROACHES
NORTHWEST WYOMING IN SOUTHWEST FLOW ALOFT. THIS SHORTWAVE HAS
ALREADY BEEN RESPONSIBLE FOR LIGHT SHOWERS OVER THE NORTHWEST, AND
IT WILL HELP INITIATE CONVECTION EARLY SUNDAY AFTERNOON. THE BEST
CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE ACROSS THE NORTH-HALF
OF THE FORECAST AREA. CONVECTIVE OUTFLOW WIND GUSTS 35-45KTS ARE
POSSIBLE WITH JUST ABOUT ANY SHOWER OR THUNDERSTORM. THE SHORTWAVE
SWEEPS EAST BEFORE SUNSET, SO COVERAGE AND INTENSITY OF CONVECTION
TRENDS DOWNWARD SUNDAY EVENING. THE MOIST, SOUTHWEST FLOW BRINGS
ANOTHER MOISTURE SURGE INTO THE SOUTH SUNDAY EVENING AND EVENTUALLY
INTO WESTERN WYOMING TOWARD 12Z/MONDAY. SCATTERED LIGHT SHOWERS
WITH GUSTY OUTFLOW WIND AROUND 35KTS WILL BE POSSIBLE INTO MONDAY
MORNING IN THESE AREAS. OUTSIDE OF CONVECTION, WESTERLY SURFACE
WIND 10-20KTS WILL BE FOUND WEST OF THE CONTINENTAL DIVIDE
BETWEEN ABOUT 20Z/SUNDAY AND 01Z/MONDAY.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZLC AND ZDV FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 9 PM MDT THIS EVENING FOR WYZ003>006-010-
011-017-018-020.
UPDATE...CNJ
DISCUSSION...STRAUB
AVIATION...CNJ
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