602
FXUS65 KRIW 152321
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
521 PM MDT MON JUN 15 2026
KEY MESSAGES
- WARM, DRY, AND BREEZY CONDITIONS WILL CONTINUE THROUGH THE
WEEK. CHANCES FOR RAIN WILL BE LOW (5 TO 10 PERCENT), MAINLY
LIMITED TO THE MOUNTAINS.
- WIND GUSTS OF 30 TO 40 MPH AND HUMIDITY OF 10 TO 20 PERCENT
WILL LEAD TO WIDESPREAD ELEVATED TO CRITICAL FIRE WEATHER
CONDITIONS ON TUESDAY AND WEDNESDAY.
UPDATE
ISSUED AT 134 PM MDT MON JUN 15 2026
THE FORECAST REMAINS ON TRACK TODAY, WITH FIRE WEATHER THE PRIMARY
WEATHER DRIVER THIS WEEK. TUESDAY AND WEDNESDAY WILL BY FAR BE THE
WINDIEST DAYS, WITH FAIRLY WIDESPREAD GUSTS OF 30 TO 40 MPH. THE
FIRE WEATHER WATCH FOR AREAS WITH CRITICAL FUELS WILL BE UPGRADED
THIS AFTERNOON. AS NOTED BELOW, VERY LITTLE CHANCE OF PRECIPITATION
THROUGH THE WEEK AS A DRY NORTHWEST FLOW PERSISTS OVER THE AREA.
DISCUSSION
ISSUED AT 216 AM MDT MON JUN 15 2026
A WARMING TREND BEGINS TODAY WITH A NORTHWEST FLOW PATTERN ALOFT IN
PLACE, AS THE RESULT OF A BROAD UPPER TROUGH ENCOMPASSING MUCH OF
CANADA AND THE CENTRAL HALF OF THE CONUS. CONDITIONS WILL BE DRY
AGAIN TODAY, WITH HIGHS NEAR 80 DEGREES RETURNING ACROSS THE CWA.
WIND GUSTS UP TO 35 MPH WILL DEVELOP OVER NORTHERN JOHNSON COUNTY BY
18Z, WITH GUSTS UP TO 25 MPH POSSIBLE AFTER 21Z ACROSS THE GREEN
RIVER BASIN AND PORTIONS OF NATRONA COUNTY. FIRE WEATHER CONDITIONS
WILL BE ELEVATED TO CRITICAL TODAY, WITH RH VALUES OF 12 TO 18%
OCCURRING FOR MOST LOWER ELEVATIONS AREAS THIS AFTERNOON. WIND, OR
THE LACK THEREOF, WILL BE THE MITIGATING FACTOR.
HEIGHTS WILL RISE TUESDAY WITHIN THIS NORTHWEST FLOW PATTERN AS A
SUBTLE RIDGE BUILDS IN FROM THE WEST. THIS WILL LEAD TO HIGH
TEMPERATURES IN THE UPPER 80S TO LOWER 90S IN THE WIND RIVER AND
BIGHORN BASINS AND PORTIONS OF NATRONA COUNTY. NORTHWEST WINDS WILL
INCREASE LATE IN THE MORNING, WITH GUSTS OF 30 TO 45 MPH EXPECTED
ACROSS MUCH OF THE CWA BETWEEN 21Z AND 03Z. THESE WINDS, COMBINED
WITH RH VALUES BELOW 15% AND ABOVE NORMAL TEMPERATURES, WILL LEAD TO
WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS. A FIRE WEATHER WATCH
WILL BE ISSUED FOR PORTIONS OF NATRONA COUNTY, DUE TO THE CRITICAL
FUELS IN THIS ZONE FOR NOW. CONDITIONS WILL REMAIN DRY, ALTHOUGH A
COUPLE HIGHER RESOLUTION MODELS ARE PROGGING VIRGA SHOWERS/DRY
THUNDERSTORMS OVER EASTERN PORTIONS OF THE BIGHORN BASIN UP AGAINST
THE WEST SLOPES OF THE BIGHORNS AND CROSSING OVER JOHNSON COUNTY
LATE IN THE AFTERNOON INTO THE EARLY EVENING. CONFIDENCE REMAINS LOW
FOR THIS TO OCCUR AT THIS TIME.
A DRY COLD FRONT WILL QUICKLY MOVE THROUGH AREAS EAST OF THE DIVIDE
LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING, REACHING THE DIVIDE A
FEW HOURS AFTER SUNRISE. THIS WILL KEEP WINDS NORTH-NORTHEASTERLY IN
THIS AREA THROUGH THE DAY, AS WELL AS DROPPING HIGH TEMPERATURES 5
TO 15 DEGREES COOLER FROM TUESDAY. WIND GUSTS OF 35 TO 45 MPH WILL
BE IN PLACE OVER NORTHERN PORTIONS IN THE WAKE OF THE FRONT, AND
SOUTHERN PORTIONS AS THE FRONT LOOKS TO REMAIN STATIONARY ALONG THE
DIVIDE THROUGH THE REST OF THE DAY.
MORE SEASONAL CONDITIONS RETURN FOR THURSDAY, WITH WINDS NOT BEING
SO STRONG. GUSTS UP TO 25 MPH LOOK TO BE CONFINED OVER SOUTHERN
PORTIONS OF THE CWA IN THE AFTERNOON. A RIDGE LOOKS TO BUILD OVER
THE REGION FROM THE WEST, MARKING A RETURN FOR TEMPERATURES IN THE
UPPER 80S AND LOWER 90S. FIRE WEATHER CONDITIONS WILL BE ELEVATED TO
CRITICAL ON THESE DAYS AS WELL, WITH RH VALUES DROPPING INTO THE
SINGLE DIGITS ACROSS THE SOUTH AND POSSIBLY INTO CENTRAL
PORTIONS.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 521 PM MDT MON JUN 15 2026
VFR CONDITIONS THROUGH THE PERIOD, WITH PASSING HIGH CLOUDS
OVERNIGHT. ANY GUSTY WINDS DECREASE WITHIN THE FIRST FEW HOURS
OF THE PERIOD LEAVING GENERALLY LIGHT WINDS TO PREVAIL
OVERNIGHT. TUESDAY IS GUSTY, WITH SURFACE WIND BEGINNING TO
INCREASE BETWEEN 14Z AND 18Z. WIDESPREAD GUSTS 25 TO 35 KNOTS
OCCUR THROUGH TUESDAY AFTERNOON. NO PRECIPITATION EXPECTED.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
FIRE WEATHER
ISSUED AT 216 AM MDT MON JUN 15 2026
ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS EXPECTED THROUGH
THE WEEK THIS WEEK. TUESDAY WILL BE THE MOST CRITICAL, WITH WIND
GUSTS OF 30 TO 45 MPH EXPECTED ACROSS MUCH OF THE FORECAST AREA.
ABOVE NORMAL TEMPERATURES AND WIDESPREAD CRITICAL RH VALUES WILL
COINCIDE WITH THE WINDS. THUS, A FIRE WEATHER WATCH HAS BEEN
ISSUED FOR ZONE 280 WHERE FUELS ARE CRITICAL AT THIS TIME.
A DRY COLD FRONT WILL QUICKLY MOVE OVER AREAS EAST OF THE DIVIDE
LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING, TURNING WINDS MORE
NORTHERLY IN THIS AREA. GUSTS OF 30 TO 45 MPH WILL RETURN FOR
NORTHERN PORTIONS OF THE FORECAST AREA IN THE WAKE OF THE FRONT,
WHILE SOUTHERN PORTIONS (ZONES 277/278/279) ALSO HAVE NORTHWEST
WINDS GUSTING 30 TO 45 MPH. RH VALUES WILL BE CRITICAL ACROSS
THE SOUTH, AS THE FRONT IS EXPECTED TO BE STATIONARY ALONG THE
DIVIDE THROUGH THE DAY WEDNESDAY.
RIW WATCHES/WARNINGS/ADVISORIES
RED FLAG WARNING FROM NOON TO 9 PM MDT TUESDAY FOR WYZ280.
UPDATE...MYERS
DISCUSSION...LAVOIE
AVIATION...CNJ/WITTMANN
FIRE WEATHER...LAVOIE
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