116  
FXUS65 KRIW 302331  
AFDRIW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RIVERTON WY  
531 PM MDT WED JUL 30 2025  
   
KEY MESSAGES  
 
- SHOWERS AND THUNDERSTORMS EXPECTED THIS AFTERNOON THAT WILL BE  
CAPABLE OF HEAVY DOWNPOURS, LARGE HAIL, STRONG GUSTY WINDS,  
AND LOCALIZED FLASH FLOODING. LOCATIONS EAST OF THE DIVIDE  
HAVE THE GREATEST POTENTIAL FOR SEEING STRONG TO SEVERE  
THUNDERSTORMS AND LOCALIZED FLASH FLOODING.  
 
- SHOWER AND THUNDERSTORM CHANCES EACH AFTERNOON THROUGH MONDAY,  
MAINLY ACROSS CENTRAL AND NORTHERN WYOMING.  
 
- ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS MAY DEVELOP  
ACROSS PORTIONS OF SOUTHERN WY AS EARLY AS THURSDAY AND  
LINGERS INTO THE WEEKEND.  
 
 
   
UPDATE  
 
ISSUED AT 1212 PM MDT WED JUL 30 2025  
 
THE MAIN STORY TODAY CONTINUES TO BE SHOWER AND THUNDERSTORM CHANCES  
(40-80%), WITH SOME THUNDERSTORMS BECOMING STRONG TO SEVERE. AS OF  
18Z, DEWPOINTS ACROSS THE STATE RANGE FROM THE 40S WEST OF THE  
DIVIDE TO 50S EAST OF THE DIVIDE. AS DAYTIME HEATING RAMPS UP EARLY  
THIS AFTERNOON, THE BOUNDARY WILL SHIFT INTO SOUTHWEST WYOMING AND  
DROP DEWPOINTS INTO THE 30S ACROSS FAR SOUTHWESTERN PORTIONS OF THE  
STATE. THUS, AREAS ALONG AND EAST OF FRONT WILL HAVE SHOWER AND  
THUNDERSTORM CHANCES TODAY.  
 
MOSTLY SUNNY SKIES THIS MORNING WILL ALLOW FOR DESTABILIZATION OF THE  
ATMOSPHERE EARLY THIS AFTERNOON. LOCATIONS EAST OF THE DIVIDE WILL  
DESTABILIZE MORE, THANKS TO DEWPOINTS IN THE 50S, AND AS A RESULT  
WILL HAVE THE GREATEST POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS.  
AS THE MORNING AFD STATES, 1000 TO 2000 J/KG OF CAPE IS  
EXPECTED. CONVECTIVE INITIATION IS FORECAST TO OCCUR ALONG THE  
BIGHORNS, ABSAROKAS, AND WESTERN MOUNTAINS AROUND OR AFTER  
1400L (20Z), AS A DISTURBANCE ALOFT MOVES THROUGH. SHOWERS AND  
THUNDERSTORMS WILL SHIFT EAST DUE TO A BUILDING UPPER-LEVEL  
RIDGE OVER THE INTERMOUNTAIN WEST. AS CONVECTION MOVES OFF THE  
MOUNTAINS, SUFFICIENT 0-6KM SHEAR OF 30-45KTS WILL FAVOR  
THUNDERSTORMS BECOMING ORGANIZED AS THEY PUSH EAST. THE MAIN  
SEVERE THREAT WILL BE LARGE HAIL. HOWEVER, SEVERE THUNDERSTORMS  
ARE NOT EXPECTED TO BE WIDESPREAD DUE TO HEIGHT RISES ALOFT.  
 
SHOWERS AND THUNDERSTORMS COULD ALSO DEVELOP (30-40% CHANCE)  
ALONG THE BOUNDARY ACROSS SOUTHERN WYOMING. THESE STORMS COULD  
PRODUCE GUSTY 40-50 MPH WINDS. THESE SHOWERS AND THUNDERSTORMS WILL  
TREK MORE NORTHEASTERLY INTO CENTRAL WYOMING BEFORE TURNING EAST.  
THIS WILL POTENTIALLY RESULT IN THUNDERSTORMS MERGING OR GOING OVER  
THE SAME LOCATIONS THAT THE THUNDERSTORMS OFF THE MOUNTAINS WENT  
ACROSS. ADDITIONALLY, PRECIPITABLE WATER AMOUNTS EAST OF THE  
DIVIDE ARE AROUND 140% OF NORMAL. THIS ABNORMALLY HIGH MOISTURE  
COMBINED WITH SUFFICIENT CAPE AND SOME LOCATIONS POTENTIALLY  
SEEING MULTIPLE SHOWERS AND THUNDERSTORMS COULD PRODUCE HEAVY  
RAINFALL. THIS COULD CAUSE ISOLATED AND VERY LOCALIZED INSTANCES  
OF FLASH FLOODING, PRIMARILY ACROSS AND AROUND JOHNSON AND  
NATRONA COUNTIES. THE FORECAST REMAINS ON TRACK FOR THURSDAY  
INTO THE WEEKEND WITH CONTINUED UNSETTLED WEATHER AND ELEVATED  
TO NEAR CRITICAL FIRE WEATHER CONDITIONS.  
 
 
   
DISCUSSION  
 
ISSUED AT 233 AM MDT WED JUL 30 2025  
 
UNSETTLED WEATHER PERSISTS ACROSS THE COWBOY STATE TODAY.  
TEMPERATURES WILL BE COOLER THAN NORMAL WITH HIGHS RANGING FROM THE  
UPPER 70S TO LOW 80S. SHOWERS AND THUNDERSTORMS RETURN, BRINGING  
WIDESPREAD CHANCES FOR SOME MUCH NEEDED MOISTURE ACROSS THE STATE,  
ESPECIALLY EAST OF THE DIVIDE. AN INFLUX OF WELL ABOVE NORMAL PWAT  
VALUES WILL LINGER OVER THE REGION. THIS WILL LEAD TO THE  
POSSIBILITY OF LOCALIZED FLASH FLOODING WITH ANY SHOWERS OR  
THUNDERSTORMS. THE OTHER CONCERN WILL BE THE CHANCE FOR STRONG TO  
SEVERE THUNDERSTORMS TO DEVELOP. PARTLY SUNNY SKIES SHOULD ALLOW FOR  
SOME DAYTIME HEATING TO OCCUR ACROSS PORTIONS OF CENTRAL AND  
NORTHERN WY. DEWPOINTS IN THE MID TO UPPER 50S COMBINED WITH  
THIS PERIOD OF HEATING SHOULD CREATE POCKETS OF INSTABILITY.  
CAMS ARE SHOWING CAPE VALUES RANGING FROM 1000 TO 2000 J/KG  
WHICH SHOULD BE SUFFICIENT TO FUEL STORM DEVELOPMENT. LOW-LEVEL  
FLOW FROM THE EAST/SOUTHEAST AND MID-LEVEL FLOW FROM THE  
SOUTHWEST/WEST WILL CREATE SOME FAVORABLE SHEAR ESPECIALLY  
ACROSS CENTRAL AND EASTERN WY. COMBINING THESE COMPONENTS SHOULD  
LEAD TO THE POTENTIAL FOR A FEW STRONG TO SEVERE THUNDERSTORMS  
MAINLY EAST OF THE DIVIDE. THE MAIN HAZARDS ASSOCIATED WITH  
THESE STORMS WOULD BE LARGE HAIL, STRONG GUSTY OUTFLOW WINDS,  
AND AS MENTIONED EARLY HEAVY DOWNPOURS. SHOWERS AND  
THUNDERSTORMS WILL LINGER THROUGH THE LATE EVENING INTO THE  
EARLY MORNING HOURS ON THURSDAY BEFORE GRADUALLY DISSIPATING BY  
SUNRISE.  
 
A TROUGH WILL CONTINUE TO MAKE ITS WAY ACROSS THE WESTERN CONUS AND  
GRADUALLY MOVE EAST THROUGH THE WEEK. UNSETTLED WEATHER WILL  
PERSIST THROUGH THE REMAINDER OF THE WEEK INTO THE WEEKEND.  
COVERAGE OF THESE SHOWERS AND THUNDERSTORMS WILL DECREASE  
THROUGHOUT THE WEEK BECOMING MORE RESTRICTED TO CENTRAL AND  
NORTHERN WY. MOISTURE WILL REMAIN ACROSS THESE AREAS AS WELL,  
WHICH SHOULD LIMIT ANY FIRE WEATHER CONCERNS FOR THE TIME BEING.  
THAT DOES NOT LOOK TO BE THE CASE FOR SOUTHERN WY WHERE DRY  
CONDITIONS WILL BE PREVALENT. MIN RH VALUES LOOK TO RETURN TO  
BELOW 20 PERCENT FOR THIS AREA HEADING INTO THE WEEKEND. THESE  
DRY CONDITIONS WILL COMBINE WITH DIURNAL WINDS OF 15 TO 25 MPH,  
WHICH MAY LEAD TO SOME ELEVATED TO NEAR CRITICAL FIRE WEATHER  
CONDITIONS. FIRE WEATHER CONCERNS MAY BEGIN TO DEVELOP AS EARLY  
AS THURSDAY CONTINUING INTO THE WEEKEND. TEMPERATURES REMAIN  
AROUND SEASONABLE VALUES INTO THE WEEKEND WITH NO SIGNIFICANT  
WARM UP INSIGHT.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/  
 
ISSUED AT 529 PM MDT WED JUL 30 2025  
 
VFR CONDITIONS WILL GENERALLY PREVAIL THROUGH THE PERIOD. HOWEVER, A  
DISTURBANCE HAS BROUGHT WIDESPREAD SHOWERS AND THUNDERSTORMS TO THE  
AREA. THESE WILL CONTINUE THROUGH THE EVENING, GENERALLY MOVING  
SOUTHWEST TO NORTHEAST ACROSS THE AREA. MOST TERMINALS CARRY A  
PROB30 OR TEMPO GROUP TO ACCOUNT FOR THIS, WITH KRKS AND KJAC THE  
EXCEPTION AS STORMS MOVE AWAY THROUGH THE NEXT HOUR OR SO. THE MAIN  
CONCERN WILL BE GUSTY OUTFLOW WIND AND BRIEFLY HEAVY RAIN, THOUGH  
STRONGER CELLS COULD BRING A LARGE HAIL RISK AS WELL. ALSO TO NOTE  
WILL BE A NORTHEASTERLY WIND SHIFT AT KRKS AFTER 03Z WITH GUSTS TO  
AROUND 30 KNOTS. CONVECTION WILL MOVE OUT OR END BY AROUND 06Z, WITH  
DECREASING CLOUDS AND CALMER WINDS EXPECTED OVERNIGHT THROUGH  
THURSDAY MORNING. THURSDAY AFTERNOON WILL FEATURE ANOTHER ROUND OF  
CONVECTION, THOUGH NOT AS WIDESPREAD; KCOD, KCPR, AND KJAC APPEAR TO  
HAVE THE BEST CHANCES AND HAVE INCLUDED PROB30 GROUPS FOR NOW.  
 
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  
 
NONE.  
 
 
 
 
 
UPDATE...GERHARDT  
DISCUSSION...DZIEWALTOWSKI  
AVIATION...MYERS  
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