399
FXUS65 KRIW 181650
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1050 AM MDT THU JUN 18 2026
KEY MESSAGES
- WARM, DRY, AND BREEZY CONDITIONS MAY LEAD TO ELEVATED FIRE
WEATHER CONDITIONS ACROSS PORTIONS OF THE STATE TODAY AND
FRIDAY.
- A NEARING DISTURBANCE LOOKS TO BRING WIDESPREAD CHANCES FOR
SHOWERS AND THUNDERSTORMS OVER THE UPCOMING WEEKEND. THE BEST
CHANCES REMAIN ALONG THE CONTINENTAL DIVIDE AND AREAS EAST,
ESPECIALLY ACROSS THE BIGHORNS AND ABSAROKAS.
- THE FIRST WEEK OF SUMMER IS LOOKING QUITE WARM WITH DAILY
CHANCES FOR SHOWERS AND THUNDERSTORMS.
DISCUSSION
ISSUED AT 214 AM MDT THU JUN 18 2026
A PLEASANT DAY IS ON TAP TODAY, WITH SEASONAL TEMPERATURES AND
MOSTLY SUNNY SKIES. THE ONE NEGATIVE ASPECT WILL BE NORTHWEST WINDS
GUSTING UP TO 30 MPH OVER AREAS WEST OF THE DIVIDE AFTER 18Z. FIRE
WEATHER CONDITIONS WILL CONTINUE TO BE ELEVATED TO CRITICAL THIS
AFTERNOON, WITH THE HIGHEST CONCERN BEING OVER SOUTHERN PORTIONS
WHERE THE AFOREMENTIONED WINDS WILL COMBINE WITH HUMIDITY VALUES AS
LOW AS 8%.
THE REST OF THE FORECAST REMAINS ON TRACK WITH LITTLE CHANGES FROM
PREVIOUS PACKAGES. A RIDGE WILL BUILD OVER THE REGION FROM THE WEST
FRIDAY, MARKING A RETURN FOR TEMPERATURES IN THE UPPER 80S TO NEAR
90 DEGREES. FIRE WEATHER CONDITIONS WILL CONTINUE TO BE ELEVATED TO
CRITICAL, WITH CRITICAL RH VALUES (<15%) OCCURRING ACROSS AREAS WEST
OF THE DIVIDE, INCLUDING THE WESTERN VALLEYS, AND CENTRAL PORTIONS
OF THE CWA. MID TO HIGH CLOUDS WILL BEGIN TO INCREASE, IN ADVANCE TO
THE INCOMING REMNANT PACIFIC LOW. THERE IS A 10% CHANCE FOR A VIRGA
SHOWER TO OCCUR UNDER THESE CLOUDS THROUGH THE AFTERNOON.
CHANCES FOR PRECIPITATION RETURN FOR THE WEEKEND, AS THE PACIFIC LOW
MOVE OVER THE REGION. NORTHERN PORTIONS OF THE CWA LOOK TO HAVE THE
BEST CHANCES TO RECEIVE ANY PRECIPITATION, WITH FORECASTED RAINFALL
AMOUNTS TRENDING DOWNWARD SLIGHTLY BETWEEN 0.25" TO 0.50" OVER
SATURDAY, SUNDAY AND MONDAY. LOCALLY HEAVY RAIN REMAINS POSSIBLE
FROM THESE STORMS, AS PRECIPITABLE WATER VALUES OF 0.60" TO 1" ARE
STILL FORECASTED. PRECIPITATION CHANCES COULD LINGER INTO MONDAY, AS
A CANADIAN COLD FRONT MOVES OVER THE AREA. DRY CONDITIONS RETURN TO
THE REGION TUESDAY, AS A STRONG AREA OF HIGH PRESSURE DEVELOPS OVER
THE DESERT SOUTHWEST. INITIAL INDICATIONS SUGGEST THAT SHORTWAVES
WILL MOVE OVER THE PACNW/NORTHERN ROCKIES FROM WEDNESDAY TO FRIDAY,
KEEPING PRECIPITATION CHANCES UP AND THE RIDGE SUPPRESSED TO THE
SOUTH.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1050 AM MDT THU JUN 18 2026
CONDITIONS REMAIN VFR THROUGH 18Z/FRIDAY WITH LITTLE MORE THAN
INCREASING HIGH CLOUDS TONIGHT AND FRIDAY MORNING. WEST-NORTHWEST
WIND GUSTING 18-26KTS INCREASES EARLY THURSDAY AFTERNOON AND
CONTINUES THROUGH 01Z-02Z/FRIDAY AT TERMINALS WEST OF THE
CONTINENTAL DIVIDE. TO THE EAST, NORTHERLY WIND GETS A SECONDARY
SURGE THURSDAY EVENING WITH WINDS GUSTING 15-20KTS BEFORE
DECREASING AFTER MIDNIGHT. BY SUNRISE FRIDAY, WIND SPEEDS WILL
BE 10KTS OR LESS ACROSS THE FORECAST AREA.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
FIRE WEATHER
ISSUED AT 214 AM MDT THU JUN 18 2026
ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS CONTINUE TODAY,
WITH CRITICAL RH VALUES ACROSS SOUTHERN ZONES, AS WELL AS ZONES
280 AND 283. WEST-NORTHWEST WINDS, WITH GUSTS UP TO 30 MPH WILL
BE CONFINED TO AREAS WEST OF THE DIVIDE IN THE AFTERNOON.
NORTHEASTERLY WINDS INCREASE OVER ZONES 280/281 AFTER 1900, WITH
GUSTS UP TO 30 MPH. THESE WINDS WILL SLOWLY DECREASE OVERNIGHT
TONIGHT, ENDING BY SUNRISE FRIDAY MORNING.
SIMILAR CONDITIONS RETURN FRIDAY, WITH WESTERLY WINDS GUSTING UP
TO 25 MPH BEING MAINLY CONFINED OVER AREAS WEST OF THE DIVIDE.
THERE WILL BE A 10% CHANCE FOR A VIRGA SHOWER ACROSS THE AREA
THROUGH THE AFTERNOON.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...LAVOIE
AVIATION...CNJ
FIRE WEATHER...LAVOIE
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