017  
FXUS65 KRIW 291601  
AFDRIW  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RIVERTON WY  
1001 AM MDT SUN JUN 29 2025  
   
KEY MESSAGES
 
 
- ELEVATED FIRE WEATHER CONTINUES ACROSS SOUTHERN WYOMING THIS  
AFTERNOON.  
 
- ISOLATED TO SCATTERED THUNDERSTORMS THIS AFTERNOON AND EARLY  
EVENING MAINLY IN JOHNSON, NATRONA, AND SWEETWATER COUNTIES.  
THUNDERSTORMS COULD BECOME STRONG TO SEVERE WITH GUSTY WINDS  
AROUND 60 MPH AND MARGINALLY SEVERE HAIL, MAINLY IN EASTERN  
JOHNSON AND NATRONA COUNTIES.  
 
- MOSTLY DRY AND WARM MONDAY AND TUESDAY WITH SHOWER AND  
THUNDERSTORM COVERAGE INCREASING WEDNESDAY AND THROUGH THE END  
OF THE WEEK.  
 

 
   
DISCUSSION
 
 
ISSUED AT 303 AM MDT SUN JUN 29 2025  
 
AS OF 2 AM, THE LAST OF THE SHOWERS HAVE ENDED AND THINGS ARE QUIET  
RIGHT NOW. LIKE YESTERDAY, WE HAVE TWO CONCERNS; ONE HAS  
IMPROVED SOMEWHAT AND ONE IS ABOUT THE SAME. THE ONE CONCERN THAT  
HAS IMPROVED AT BIT IS FIRE WEATHER. WE WILL NOT HAVE ANY RED  
FLAG WARNINGS TODAY. FLOW HAS TURNED TO THE NORTH OR NORTHEAST  
EAST OF THE DIVIDE DUE TO A WEAK FRONTAL BOUNDARY AND THAT HAS  
BROUGHT SOMEWHAT COOLER TEMPERATURES AND HIGHER HUMIDITY. AS A  
RESULT, CRITICAL FIRE WEATHER IS NOT EXPECTED HERE, ALTHOUGH  
LOCAL ELEVATED FIRE WEATHER IS STILL POSSIBLE. ELEVATED TO  
CRITICAL FIRE WEATHER WILL CONTINUE IN SOUTHERN WYOMING, BUT  
FUELS ARE NOT CRITICAL HERE.  
 
THE CONCERN THAT IS THE SAME IS THE CHANCE OF CONVECTION. WE DO HAVE  
AN AREA OF MARGINAL RISK LARGELY ALONG AND EAST OF INTERSTATE  
25. THE BEST CHANCE WILL BE IN EASTERN PORTIONS OF THE AREA,  
CLOSE TO THE FRONTAL BOUNDARY AND IN THE AREA WITH SOMEWHAT  
HIGHER DEWPOINTS. INSTABILITY PARAMETERS ARE DECENT, ESPECIALLY  
IN THE MARGINAL RISK AREA WITH OVER 1000 J/KG OF CAPE AND  
LIFTED INDICES AS LOW AS MINUS 3. LAPSE RATES ARE DECENT AS  
WELL, WITH SOME SHEAR (CLOSE TO 40 KT). THERE WILL ALSO BE AN  
APPROACHING JET STREAK TO ENHANCE LIFT SOMEWHAT. FOR NOW, HAVE  
KEPT STORM CHANCES LARGELY FROM THE BIGHORN RANGE EASTWARD. THE  
MAIN RISK FROM ANY THUNDERSTORM WOULD BE GUSTY WIND AND/OR  
SMALL HAIL, ALTHOUGH THERE COULD BE A FEW STORMS THAT HAVE  
MARGINALLY SEVERE HAIL. THIS LOOKS LIKE AN EARLIER SHOW, WITH  
MOST STORMS OVER SHORTLY AFTER SUNSET. COVERAGE DOES NOT LOOK  
VERY BIG THOUGH, AT MOST 1 OUT OF 3 AT ANY PARTICULAR LOCATION.  
OTHERWISE, EXPECT A SEASONABLE DAY ACROSS THE AREA.  
 
MOST AREAS SHOULD HAVE A NICE SUMMER DAY TO END THE MONTH OF JUNE ON  
MONDAY WITH LOTS OF SUNSHINE, WARM BUT NOT HOT TEMPERATURES AND,  
THANKFULLY, LIGHTER WIND. I CAN'T COMPLETELY RULE OUT A SHOWER OR  
THUNDERSTORM, BUT THE CHANCE IS LESS THAN 1 OUT OF 10 SO WE KEPT THE  
FORECAST DRY FOR NOW. THE CHANCE OF THUNDERSTORMS INCREASES AGAIN ON  
TUESDAY AS MOISTURE BEGINS TO MOVE IN FROM THE SOUTH, BUT THIS WOULD  
INITIALLY BE OF THE MID LEVEL VARIETY. STORMS ON THIS DAY WOULD  
LIKELY STAY NEAR THE MOUNTAINS WITH ONLY AROUND A 1 IN 6 CHANCE  
AT ANY LOCATION. MOISTURE RETURN HAS SLOWED SOMEWHAT IN THE  
LATEST MODEL RUNS FOR WEDNESDAY, SO WE DID TRIM POPS SOMEWHAT.  
A SHORTWAVE AND MUCH DEEPER MOISTURE MOVING IN NOW MAKES  
THURSDAY A MORE LIKELY TIME FOR THE ARRIVAL OF MORE WIDESPREAD  
SHOWERS AND STORMS. THIS COULD ESPECIALLY BE THE CASE ON  
THURSDAY AND FRIDAY, AS SOME GUIDANCE SHOWS SOME PRECIPITABLE  
WATER VALUES POSSIBLY CLIMBING AS HIGH AS 200 PERCENT OF NORMAL  
(FOR EXAMPLE, AROUND 1.2 INCHES AT OUR OFFICE, NORMAL IS CLOSER  
TO 0.60 INCHES). A LOT WILL DEPEND OF THE PROGRESS OF AN UPPER  
LEVEL LOW NOW OFF THE CALIFORNIA COAST AND MOVE EVENTUALLY OPEN  
UP AND MOVE NORTHEASTWARD. THESE ARE NOTORIOUSLY FICKLE AND HARD  
TO TIME AND TRACK, ESPECIALLY THIS FAR OUT. HOWEVER, WE HAVE  
THE POTENTIAL FOR AN ACTIVE PERIOD OF SHOWERS AND STORMS LATER  
NEXT WEEK. AS FOR TEMPERATURES, LOOK FOR ABOVE NORMAL TEMPS THROUGH  
AROUND WEDNESDAY, WITH COOLER TEMPERATURES LATER NEXT WEEK AS  
CLOUD COVER INCREASES FROM THE INCREASED MOISTURE AND POSSIBLE  
SHOWERS/THUNDERSTORMS.  
 

 
   
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
 
 
ISSUED AT 346 AM MDT SUN JUN 29 2025  
 
MVFR CEILINGS HAVE DEVELOPED NEAR KCPR THIS MORNING, BUT SHOULD  
DISPERSE/IMPROVE BY 15Z/16Z. OTHERWISE, SKC SKIES WILL BE IN  
PLACE ACROSS MUCH OF THE FORECAST AREA THROUGH THE TAF PERIOD.  
WINDS WILL BE DIURNALLY DRIVEN, INCREASING A BIT DURING THE  
AFTERNOON. A COLD FRONT PUSHES IN FROM THE NORTH LATE IN THE  
AFTERNOON AND THROUGH THE EVENING, WITH WINDS FROM THE EAST-  
NORTHEAST BEHIND IT. VIRGA SHOWERS WILL BE POSSIBLE (15%  
CHANCE) OVER PORTIONS OF JOHNSON AND NATRONA COUNTIES IN THE  
AFTERNOON, WITH BETTER CHANCES (30%) AROUND THE WY/UT/CO BORDER.  
 
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.  
 

 
 

 
 
DISCUSSION...HATTINGS  
AVIATION...LAVOIE/WITTMANN  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WY Page Main Text Page