040
FXUS65 KRIW 021800
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1200 PM MDT SUN AUG 2 2026
KEY MESSAGES
- SUNDAY REMAINS UNSEASONABLY HOT WITH WIDESPREAD HIGH
TEMPERATURES IN THE 90S AND LOWER 100S FOR MANY LOWER
ELEVATION LOCATIONS. MORE RECORD HIGH TEMPERATURES ARE
POSSIBLE SUNDAY AFTERNOON.
- LOW HUMIDITY AND A GUSTY WESTERLY WIND COMBINE WITH THE HEAT
TO PRODUCE ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS FOR
MUCH OF THE REGION BEGINNING MID-AFTERNOON SUNDAY. THE DRY,
WARM, AND BREEZY CONDITIONS PERSIST ACROSS SOUTHWEST WYOMING
ON MONDAY.
- A COLD FRONT SWEEPS SOUTH SUNDAY NIGHT AND MONDAY MORNING
PROVIDING COOLER AIR TO WYOMING FOR MONDAY AND TUESDAY,
ESPECIALLY IN NORTHERN AND CENTRAL WYOMING. TEMPERATURES WILL
BE 10 TO 20 DEGREES, AND AS MUCH AS 25 DEGREES, COOLER THAN
SUNDAY.
- THE UPCOMING WORK WEEK LOOKS MOSTLY DRY WITH A SLOW WARMING
TREND BEGINNING MIDWEEK. ABOVE NORMAL TEMPERATURES LIKELY
RETURN BY THURSDAY.
UPDATE
ISSUED AT 1200 PM MDT SUN AUG 2 2026
AN UPPER LOW IN THE CANADIAN ROCKIES IS KEEPING WARM WEST-SOUTHWEST
FLOW ACROSS WESTERN AND CENTRAL WYOMING SUNDAY. CIRRUS CLOUDS HAVE
BEEN STREAMING ACROSS THE REGION WITHIN THIS PATTERN, ALLOWING FOR
STANDING WAVE CLOUDS TO FORM DOWNSTREAM OF THE ABSAROKA, BIGHORN,
AND WIND RIVER RANGES SUNDAY MORNING. SIMILAR TO SATURDAY, 700MB
TEMPERATURES CLIMB TO AROUND 20C LEADING TO ANOTHER HOT DAY. MORE
RECORDS ARE IN JEOPARDY TODAY. HEAT ADVISORIES REMAIN IN EFFECT
UNTIL 10 PM. WEST-SOUTHWEST WIND INCREASES BETWEEN 1 PM AND 3 PM
SUNDAY AFTERNOON LEADING TO CRITICAL FIRE WEATHER CONDITIONS FOR
MANY LOWER ELEVATION LOCATIONS UNTIL AROUND SUNSET. A RED FLAG
WARNING CONTINUES UNTIL 9 PM SUNDAY. THE ATMOSPHERE IS DRY WITH
SURFACE DEW POINTS IN THE 20S AND 30S AND PRECIPITABLE WATER
BELOW ONE-HALF INCH. THE LATEST KRIW 18Z SOUNDING SHOWS IT BEING
VERY DRY UP TO 300MB. THERE DOES APPEAR TO BE JUST ENOUGH
500-400MB LAYER MOISTURE ACROSS FAR SOUTHERN WYOMING TO GENERATE
SOME WEAK VIRGA SHOWERS OFF THE UINTA MOUNTAINS LATE SUNDAY
AFTERNOON. SEVERAL CAMS ALSO HINT AT THIS POSSIBILITY. THESE
WOULD DO LITTLE MORE THAN GENERATE GUSTY OUTFLOW WIND ACROSS THE
SOUTHERN-THIRD OF SWEETWATER COUNTY.
AN INITIAL SURFACE COLD FRONT IS STILL ON-TRACK TO PUSH THROUGH
AREAS EAST OF THE CONTINENTAL DIVIDE SUNDAY NIGHT. A BETTER PUSH
COMES DURING THE DAY MONDAY AS A SHORTWAVE TRAILING THE UPPER LOW
MOVES EAST THROUGH MONTANA. GUSTY NORTH WIND 15 TO 30 MPH AND MUCH
COOLER TEMPERATURES FOLLOW THE FRONT, WITH DAYTIME HIGHS FROM THE
LOWER 70S TO LOWER 80S EAST OF THE CONTINENTAL DIVIDE. WEST OF THE
DIVIDE, RED FLAG WARNINGS CONTINUE DUE TO LOW RELATIVE HUMIDITY
AND A CONTINUING WESTERLY WIND 15 TO 30 MPH.
DISCUSSION
ISSUED AT 1236 AM MDT SUN AUG 2 2026
IT CERTAINLY HAS BEEN A HOT STRETCH IN WYOMING THROUGH JULY AND
STARTING AUGUST. FOR EXAMPLE, AT THE HUMBLE RIVERTON WEATHER ABODE,
OF THE PAST 29 DAYS, 28 HAVE AVERAGED ABOVE NORMAL. AND THE ONE DAY
THAT WAS BELOW AVERAGE, JULY 23RD, WAS ONLY 0.2 DEGREES BELOW
NORMAL. WE HAVE HAD 7 HIGH TEMPERATURES OVER 100, WE TYPICALLY
AVERAGE LESS THAN 1 A YEAR. AND WE WILL ALMOST CERTAINLY HAVE
ANOTHER ONE TODAY. HOWEVER, THERE IS SOMETHING MOVING TOWARD THE
AREA THAT WILL BRING A WELCOME BREAK FROM ONE OF THE HOTTEST
SUMMERS WE HAVE HAD IN QUITE A WHILE. MORE ON THAT LATER IN THE
DISCUSSION.
BUT WE HAVE ONE MORE SCORCHING HOT DAY TO GET THROUGH. WE HAD
SEVERAL RECORD HIGHS THAT WERE BROKEN OR TIED YESTERDAY, INCLUDING
AN ALL TIME AUGUST RECORD HIGH TEMPERATURE AT THE RIVERTON AIRPORT.
IT WAS ALSO THE FIRST TIME IT HAS BEEN 100 AT THE AIRPORT IN THE
MONTH OF AUGUST (SINCE 1996 WHEN THE ASOS WAS COMMISSIONED).
THE 700 MILLIBAR TEMPERATURES LOOK LARGELY UNCHANGED FROM
YESTERDAY, SO THE HIGH TEMPERATURES FORECASTED FOR SUNDAY ALSO
LOOK RELATIVELY UNCHANGED. WITH A SOUTHWESTERLY BREEZE DEVELOPING,
THE AREAS THAT WILL BE WARMER WILL BE THE DOWNSLOPE LOCATIONS.
THESE INCLUDE THE SOUTHERN BIGHORN BASIN, THE WIND RIVER BASIN
AND LANDER FOOTHILLS AND PORTIONS OF SWEETWATER COUNTY. WE WILL
LIKELY SEE MORE DAILY RECORD HIGH TEMPERATURES TODAY. SOME ALL
TIME AUGUST HIGH TEMPERATURES RECORDS COULD ALSO BE IN JEOPARDY.
IT STILL LOOKS LIKE ELEVATIONS BELOW AROUND 5800 FEET HAVE AT
LEAST A 1 IN 2 CHANCE OF HIGH TEMPERATURES OVER 100F. AS FOR
HIGHS OF 105F, THE 1 IN 2 CHANCE IS LARGELY BELOW 4500 FEET,
MAINLY IN PORTIONS OF FREMONT COUNTY AS WELL THE BIG HORN BASIN
FROM THERMOPOLIS TO WORLAND. AND THE GUSTY BREEZE WILL ALSO
BRING INCREASED FIRE WEATHER CONCERNS. THIS, COMBINED WITH
RELATIVE HUMIDITY FALLING AS LOW AS 5 PERCENT, WILL BRING AT
LEAST ELEVATED FIRE WEATHER TO THE ENTIRE AREA. A RED FLAG
WARNING IS IN EFFECT FOR MUCH OF THE AREA, AND WE WILL CONTINUE
IT. I DID GIVE SOME THOUGHT TO INCLUDING NATRONA COUNTY, BUT
STILL HAVE SOME DOUBTS IF THE WIND WILL BE OF SUFFICIENT
STRENGTH OR DURATION. NEVERTHELESS, BURNING IS STRONGLY
DISCOURAGED ANYWHERE IN WESTERN AND CENTRAL WYOMING TODAY.
THE RELIEF FROM THE HEAT FOR SOME WILL COME IN THE FORM OF A COLD
FRONT DROPPING SOUTHWARD OUT OF MONTANA TONIGHT AND TOMORROW. IT
WILL BEGIN TO WEAKEN AS IT MOVES THROUGH THE AREA MONDAY, BUT ALL
AREAS WILL SEE A DROP IN TEMPERATURES. THE MOST PRONOUNCED DROPS
WILL BE ACROSS NORTHERN WYOMING WHERE PLACES CODY COULD SEE
TEMPERATURES 25 DEGREES COOLER THAN TODAY WITH IT FEELING MORE LIKE
SEPTEMBER. MOST LOCATIONS EAST OF THE DIVIDE WILL SEE AROUND A 15 TO
20 DEGREE DROP IN TEMPERATURES, WITH SOME LOCATIONS SEEING THE
COOLEST TEMPERATURES SINCE JUNE. IT WILL ALSO COOL OFF WEST OF THE
DIVIDE, BUT NOT AS MUCH. HOWEVER, 8 TO 15 DEGREES WILL STILL FEEL
BETTER. WE STILL HAVE FIRE WEATHER CONCERNS ON THIS DAY THOUGH. IN
NORTHERN AND CENTRAL WYOMING, THE COOLER TEMPERATURES AND SOMEWHAT
HIGHER HUMIDITY SHOULD KEEP CONDITIONS BELOW CRITICAL DESPITE A
GUSTY NORTHERLY BREEZE. MUCH OF SOUTHERN WYOMING WILL STILL HAVE
HUMIDITY UNDER 15 PERCENT THOUGH. AND WITH THE CONTINUED WIND WITH
THE FRONT IN THE AREA, CRITICAL FIRE WEATHER STILL LOOKS LIKELY SO
THE RED FLAG WARNING WILL BE CONTINUED.
TUESDAY LOOKS LIKE THE COOLEST DAY ACROSS MUCH OF THE AREA. THERE
WILL STILL BE A BIT OF A BREEZE AND HUMIDITY REMAINS LOW SO WE MAY
NEED MORE FIRE WEATHER HIGHLIGHTS FOR THIS DAY AS WELL ALTHOUGH IT
IS MORE BORDERLINE. WE WILL HAVE MORE TIME TO LOOK AT THAT IN FUTURE
SHIFTS. FOLLOWING THAT, THE RIDGE SHOULD AGAIN BUILD ACROSS THE
DESERT SOUTHWEST AND THEN BUILD BACK NORTHWARD INTO WYOMING.
THIS MEANS TEMPERATURES RISING AGAIN BY WEDNESDAY WITH ABOVE
NORMAL TEMPERATURES AGAIN LIKELY FROM THURSDAY INTO NEXT
WEEKEND, WITH 90S ONCE AGAIN LIKELY IN MANY OF THE LOWER
ELEVATIONS. AS FOR ANY PRECIPITATION CHANCES, THERE ARE RATHER
SLIM PICKINGS. A WEAK SHORTWAVE WILL MOVE ACROSS NORTHERN
WYOMING AND MAY BRING A FEW SHOWERS AND STORMS TUESDAY AFTERNOON
OR EVENING BUT WITH LITTLE MOISTURE AVAILABLE COVERAGE LOOKS
RATHER SPARSE. MAINLY DRY WEATHER THEN CONTINUES FOR THE REST OF
THE WEEK. THERE ARE SOME INDICATIONS IN SOME OF THE LONG RANGE
GUIDANCE OF THE RIDGE WEAKENING EARLY NEXT WEEK AND MAYBE SOME
MONSOONAL MOISTURE RETURNING FOR EARLY NEXT WEEK BUT A LOT OF
UNCERTAINTY THIS FAR OUT. SO, ENJOY THE BRIEF BREAK FROM THE HOT
WEATHER EARLY THIS WEEK BECAUSE IT WILL LIKELY NOT LAST LONG.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1041 AM MDT SUN AUG 2 2026
THERE IS HIGH CONFIDENCE IN DRY AND VFR FLIGHT CONDITIONS THROUGH AT
LEAST 18Z MONDAY. GUSTY SOUTHWEST TO WEST WINDS ARE FORECAST AT ALL
TERMINALS BY 21Z, WITH GUSTS IN THE 20KT TO 25KT RANGE. OCCASIONAL
GUSTS CLOSER TO 30KTS ARE POSSIBLE AT KCPR, KJAC, AND KBPI. THESE
GUSTY WINDS ARE EXPECTED TO DIMINISH TO 10KTS OR LESS BY 03Z MONDAY
AT MOST TERMINALS. KRIW IS THE EXCEPTION WITH SUSTAINED NORTHWEST
WINDS UP TO 16KTS THROUGH THE OVERNIGHT HOURS. A COLD FRONT BEGINS
TO PUSH INTO WYOMING FROM THE NORTH AFTER 05Z AT KCOD AND SHIFT
WINDS TO BE MORE FROM THE NORTHWEST. ALL OTHER TERMINALS HAVE A
NORTHWEST TO NORTH WIND SHIFT AFTER 11Z MONDAY AS THE COLD FRONT
DROPS SOUTH. SMOKE WILL BE MORE NOTICEABLE ACROSS THE STATE DUE TO
INCREASED WILDFIRE ACTIVITY ACROSS THE WESTERN UNITED STATES,
ESPECIALLY AT KJAC.
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 1236 AM MDT SUN AUG 2 2026
A COMBINATION OF VERY HOT TEMPERATURES, HUMIDITY FALLING INTO
THE SINGLE DIGITS AND A GUSTY SOUTHWESTERLY BREEZE WILL BRING
ELEVATED TO CRITICAL FIRE WEATHER TO MOST OF THE AREA TODAY. A
COLD FRONT DROPS SOUTHWARD ON MONDAY. FIRE CONCERNS SHOULD
LESSEN ACROSS NORTHERN AND CENTRAL WYOMING AS COOLER
TEMPERATURES AND HIGHER HUMIDITY MOVES IN BEHIND THE FRONT.
HOWEVER, IN SOUTHERN WYOMING, CRITICAL FIRE WEATHER SHOULD
CONTINUE WITH A GUSTY WIND AND RELATIVE HUMIDITY REMAINING BELOW
15 PERCENT.
RIW WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 10 PM MDT THIS EVENING FOR WYZ003>006-010-
011-013-016>020-023-025>030.
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR WYZ275-276-
282-283-285.
RED FLAG WARNING UNTIL 9 PM MDT MONDAY FOR WYZ277>279-289.
UPDATE...CNJ
DISCUSSION...HATTINGS
AVIATION...GERHARDT
FIRE WEATHER...HATTINGS
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