568  
FXUS65 KRIW 051828  
AFDRIW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RIVERTON WY  
1228 PM MDT SAT JUL 5 2025  
   
KEY MESSAGES
 
 
- SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING, WITH A  
CHANCE FOR SEVERE STORMS, ESPECIALLY IN THE BIGHORN BASIN, THE  
BIGHORN MOUNTAINS, AND JOHNSON COUNTY. HAIL AND STRONG WINDS  
ARE THE MAIN HAZARDS.  
 
- DRIER WEATHER RETURNS SUNDAY, WITH WARMER CONDITIONS AND  
INCREASING CHANCES FOR ELEVATED FIRE WEATHER FROM MONDAY TO  
WEDNESDAY.  
 

 
   
UPDATE
 
 
ISSUED AT 1226 PM MDT SAT JUL 5 2025  
 
CURRENT RADAR HAS SOME SHOWERS AND WEAK STORMS OVER FAR NORTHWEST  
WYOMING. A FEW STORMS ARE BEGINNING TO DEVELOP FURTHER  
EAST/SOUTHEAST AS INSTABILITY INCREASES WITH THE AFTERNOON SUN.  
 
LATEST HI-RES MODEL TRENDS KEEP A SIMILAR SET-UP TO THE PREVIOUS  
MORNING DISCUSSION (SEE BELOW DISCUSSION). THE HRRR HAS SOME 50 TO  
60 MPH OUTFLOWS IN THE BIGHORN BASIN AND EAST OVER JOHNSON COUNTY  
BETWEEN 2PM AND 9PM. RAP MESOANALYSIS ALSO KEEPS CAPE AND SHEAR  
VALUES INDICATIVE OF 1" OR GREATER HAIL FOR ANY STRONGER STORMS.  
 
AS THE CONVECTIVE ACTIVITY WINDS DOWN LATE EVENING, A COLD FRONT  
PUSHES SOUTHWARDS INTO THE BIGHORN BASIN AND JOHNSON/NATRONA  
COUNTIES. THIS MAY BRING NORTHERLY GUSTS AROUND 30 MPH, WITH SOME  
MODELS INDICATING GUSTS 40 TO 45 MPH. THESE WINDS SHOULD DECREASE  
WITHIN A FEW HOURS, AFTER THE FRONT PASSES.  
 

 
   
DISCUSSION
 
 
ISSUED AT 133 AM MDT SAT JUL 5 2025  
 
SHOWERS CONTINUE TO END ACROSS THE CWA EARLY THIS MORNING AND ARE  
EXPECTED TO DISSIPATE NO LATER THAN SUNRISE. CLOUDS WILL SCATTER OUT  
THROUGH THIS TIME WITH ONLY HIGH CLOUDS OVER FAR WESTERN PORTIONS.  
THIS WOULD LEAVE MOSTLY CLEAR SKIES FOR THE REST OF THE AREA, WHICH  
COULD LEAD TO THE POSSIBILITY FOR FOG (ESPECIALLY LOWER LYING AREAS  
ALONG THE RIVERS AND CREEKS). HOWEVER, ANY FOG THAT WOULD FORMED  
WOULD BE SHORT-LIVED DUE TO THE APPROACHING SYSTEM.  
 
A SHORTWAVE TROUGH WILL MOVE ACROSS THE NORTHERN HALF OF THE CWA  
TODAY, PROVIDING SUFFICIENT LIFT AND UPPER LEVEL DIVERGENCE FOR  
SHOWERS AND THUNDERSTORMS. THIS ACTIVITY WILL MAINLY OCCUR EAST OF  
THE DIVIDE, BUT WILL EXTEND OVER THE WIND RIVER MOUNTAINS AND THE  
NORTHERN HALF OF THE UPPER GREEN RIVER BASIN. LOW LEVEL MOISTURE  
WILL REMAIN IN PLACE THIS MORNING, WITH DEWPOINTS IN THE 40S TO  
MIDDLE 50S FOR MOST AREAS TODAY. LOW LEVEL LAPSE RATES OF 7 TO 9  
C/KM WILL BE PREVALENT AS WELL, ALONG WITH LIFTED INDICES OF MINUS 4  
TO MINUS 6. MIXED LAYER CAPE OF 500 TO 1500 J/KG AND BULK SHEAR OF  
30 TO 40 KT WILL ALL COMBINE FOR ANOTHER DAY FOR STRONG TO  
SEVERE THUNDERSTORMS. THE BIGHORN BASIN WILL HAVE THE BEST  
CHANCE FOR THESE STORMS MOVES THROUGH THE AREA BETWEEN 19Z AND  
00Z. THIS LINE WILL QUICKLY PUSH EASTWARD OVER THE BIGHORNS AND  
NORTHERN JOHNSON COUNTY BY 22Z AND EXIT THE CWA AFTER 01Z. WIND  
GUSTS OF 60 TO 70 MPH IS EXPECTED AGAIN WITH THIS ACTIVITY  
(SIMILAR TO WHAT OCCURRED FRIDAY), BUT LARGE HAIL (1 INCH OR  
HIGHER) CANNOT BE RULED OUT. ADDITIONAL SHOWERS AND  
THUNDERSTORMS WILL DEVELOP FROM THE WIND RIVER BASIN TO THE  
UPPER GREEN RIVER BASIN (AS PREVIOUSLY MENTIONED) AS THE TAIL  
END OF THE SHORTWAVE MOVES OVER THE AREA. THESE STORMS ARE NOT  
EXPECTED TO BE AS SEVERE, BUT WIND GUSTS UP TO 60 MPH COULD  
STILL OCCUR ALONG WITH SMALL HAIL. NO SHOWERS OR THUNDERSTORMS  
ARE EXPECTED OVER SWEETWATER COUNTY OR SOUTHERN LINCOLN COUNTY,  
DUE TO A LACK OF INSTABILITY. CONVECTION WILL EXIT THE AREA BY  
SUNSET WITH ONLY ISOLATED SHOWERS REMAINING POSSIBLE THROUGH  
06Z, MAINLY OVER NATRONA COUNTY. A WEAK COLD FRONT FROM THE  
SHORTWAVE WILL DROP SOUTHWARD OVER AREAS EAST OF THE DIVIDE  
DURING THIS TIME, QUICKLY REACHING THE DIVIDE AND INTO THE WIND  
RIVER BASIN BY 09Z. THIS WILL ONLY RESULT IN THE OBVIOUS WIND  
SHIFT AND SLIGHTLY DROPPING TEMPERATURES A FEW DEGREES SUNDAY  
MORNING.  
 
THE PASSAGE OF THIS SHORTWAVE WILL MARK THE END OF THIS LATEST  
ACTIVE WEATHER PATTERN, AS DRIER AIR MOVES INTO THE REGION. FLAT  
RIDGING WILL BE IN PLACE SUNDAY, WITH THE FRONT WASHING OUT THROUGH  
THE DAY AND KEEPING DAYTIME TEMPERATURES SIMILAR TO TODAY. THE FOCUS  
WILL SHIFT TO FIRE WEATHER, AS AN UPPER LEVEL RIDGE BUILDS OVER THE  
REGION FROM A STRENGTHENING HIGH CENTER OVER THE FOUR CORNERS.  
WINDS LOOK TO REMAIN LIGHT THROUGH WEDNESDAY, HOWEVER 90 DEGREE  
TEMPERATURES WILL RETURN BY TUESDAY FOR AREAS EAST OF THE  
DIVIDE. LOCATIONS ON THE EAST SIDE OF THE BIGHORN BASIN, SUCH AS  
GREYBULL AND WORLAND, COULD POSSIBLY REACH 100 DEGREES BY  
WEDNESDAY.  
 
THE NEXT CHANCE FOR PRECIPITATION LOOKS TO OCCUR THURSDAY,AS A  
REMNANT LOW MOVES OVER THE NORTHERN SIDE OF THE FOUR CORNERS HIGH.  
THIS WOULD LOWER TEMPERATURES A BIT AN D CAUSE THE HIGH TO RETREAT  
FURTHER SOUTH. THERE IS A CHANCE THIS LOW COMES IN PHASE WITH TROUGH  
THAT WILL PASS OVER SOUTHERN CANADA. THIS COULD LEAD TO MORE  
WIDESPREAD PRECIPITATION CHANCES, BUT WILL HAVE TO SEE HOW TO  
FORECAST EVOLVES OVER THE COMING DAYS.  
 

 
   
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
 
 
ISSUED AT 1056 AM MDT SAT JUL 5 2025  
 
SHOWERS AND THUNDERSTORMS ARE ALREADY BEGINNING TO BUILD OVER  
FAR NORTHWEST WY, AND WILL EXPAND ACROSS NORTHERN AND CENTRAL WY  
THIS AFTERNOON. BEST CHANCES STILL LOOK TO BE KCOD/KWRL, SO HAVE  
ADDED TEMPO GROUPS FOR THOSE SITES, AS CONFIDENCE IS HIGHER  
THERE. SHOWERS WILL BUILD AROUND KJAC/KLND/KRIW/KCPR LATER THIS  
AFTERNOON, BUT CHANCES AT THESE SITES ARE LOWER. SHOWER ACTIVITY  
WILL BE MOVING EAST QUICKLY THIS EVENING, SO MOST PRECIP SHOULD  
BE DONE BY 00Z. SKIES REMAIN MOSTLY CLEAR OVERNIGHT WITH LIGHTER  
WINDS.  
 

 
   
RIW WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
 
UPDATE...WITTMANN  
DISCUSSION...LAVOIE  
AVIATION...STRAUB  
 
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