724
FXUS65 KRIW 280404
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1004 PM MDT SAT JUN 27 2026
KEY MESSAGES
- SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO WANE THIS
EVENING. SHOWERS WILL BECOME CONFINED OVER FAR NORTHWESTERN
PORTIONS TONIGHT. AN ADDITIONAL LINE OF SHOWERS WILL DEVELOP
LATE TONIGHT, FROM CENTRAL SWEETWATER COUNTY TO NATRONA
COUNTY.
- ELEVATED FIRE WEATHER RETURNS SUNDAY FOR AREAS EAST OF A ROCK
SPRINGS TO WORLAND TO KAYCEE LINE.
- COOLER WEATHER MOVES IN TONIGHT AND SUNDAY, ESPECIALLY WEST
OF THE DIVIDE. SNOW IS POSSIBLE IN THE MOUNTAINS TONIGHT INTO
MONDAY, WITH THE POTENTIAL FOR FROST IN THE WESTERN VALLEYS,
ESPECIALLY ON MONDAY NIGHT.
UPDATE
ISSUED AT 1235 PM MDT SAT JUN 27 2026
THINGS REMAIN ON TRACK FOR TODAY, WITH STORMS OCCURRING THROUGH THIS
EVENING (MOST ENDING BETWEEN 6PM AND 8PM). THE MAIN HAZARD CONTINUES
TO BE WIND, WITH THE LATEST HRRR RUNS PROJECTING WIND GUSTS 45 TO 65
MPH, THOUGH AN ISOLATED STRONGER WIND IS NOT OUT OF THE QUESTION.
THOUGH WIND IS THE MAIN HAZARD, THE STRONGEST STORMS TODAY COULD
ALSO PRODUCE SOME LARGE HAIL (GREATER THAN 1 INCH). CURRENT
SATELLITE IMAGERY SHOWS THE PERSISTENT SOUTHWEST FLOW MOVING INTO
THE AREA, BRINGING MOISTURE FOR THE SHOWERS AND STORMS, AS WELL AS
SOME SMOKE FROM THE UTAH FIRES.
DISCUSSION
ISSUED AT 227 AM MDT SAT JUN 27 2026
RIGHT NOW, IT RELATIVELY "Q-WORD" WEATHER-WISE AROUND WESTERN
AND CENTRAL WYOMING AND THE HUMBLE RIVERTON ABODE. IF YOU ARE
WONDERING WHAT THE "Q-WORD" IS, JUST ASK ANY PEOPLE WHO ARE
POLICE OFFICERS, FIREFIGHTERS, PARAMEDICS OR NURSES. MY MOTHER,
WHO IS A RETIRED NIGHT SHIFT NURSE, TOLD ME TO NEVER UTTER THAT
WORD WHILE AT WORK, AS IF NOT TO JINX YOURSELF. BUT, AS THE
PATTERN HAS BEEN OVER THE PAST SEVERAL DAYS, IT WILL NOT LAST.
WE CONTINUE TO HAVE MULTIPLE IMPACTS TO THE WEATHER TODAY AND
TOMORROW. AND WE WILL ADDRESS THEM IN THIS ORDER: STRONG TO SEVERE
THUNDERSTORMS, FIRE WEATHER AND MUCH COLDER WEATHER AND THE
POSSIBILITY OF THE "S" WORD, AND BY THAT I MEAN SNOW. THE CULPRIT OF
THIS WILL BE ANOTHER SHORTWAVE MOVING AROUND A PARENT UPPER LEVEL
LOW NOW MOVING ONSHORE IN THE PACIFIC NORTHWEST AND PROGRESSING
SOUTH AND EAST TOWARD THE AREA BEFORE TURNING NORTHEASTWARD INTO
IDAHO AND WESTERN MONTANA. THIS WILL BRING SOMEWHAT COOLER
TEMPERATURES TODAY, AND THE TIGHTENING PRESSURE GRADIENT AND THE
NEARBY JET STREAM WILL BRING BREEZY TO WINDY CONDITIONS, ESPECIALLY
ACROSS THE SOUTHERN TWO-THIRDS OF THE AREA.
STRONG TO SEVERE THUNDERSTORMS...FOR THE SEVENTH OF THE PAST EIGHT
DAYS, WE ARE UNDER SOME KIND OF A CONVECTIVE OUTLOOK. IN THIS CASE,
A MARGINAL RISK THAT COVERS JUST ABOUT THE ENTIRETY OF WESTERN
AND CENTRAL WYOMING. INSTABILITY IS NOT AS HIGH AS THE BEST FEW
DAYS, WITH THE HIGHEST IN FAR WESTERN WYOMING WHERE CAPE VALUES
RISE AS HIGH AS 1000 J/KG, WITH LESSENING VALUES FURTHER EAST
AS YOU HEAD INTO DRIER AIR. ONE FACTOR FOR SEVERE THUNDERSTORMS
WILL BE A POTENT 100 KNOT JET THAT WILL BE PASSING ACROSS
SOUTHERN WYOMING, BRINGING SOME UPPER LEVEL DIVERGENCE AND THE
APPROACHING UPPER LEVEL LOW WILL BRING SOME LIFT AS WELL.
AS FOR THE THREATS, FOR TORNADOES, WE CAN'T RULE ONE OUT, BUT
THE CHANCE IS VERY SMALL. THE NEXT THREAT, STRONG WIND, LOOKS TO
BE MOST WIDESPREAD THREAT. THE MAIN AREA OF CONCERN FOR THIS IS
EAST OF THE DIVIDE AND SOUTHERN WYOMING, WHERE MODEL SKEW T
SOUNDINGS HAVE INVERTED-V SIGNATURES AND DRIER AIR AT THE
SURFACE SHOULD ALLOW FOR SOMEWHAT HIGHER CLOUD BASES. DEWPOINT
DEPRESSIONS GENERALLY RANGE FROM 35 TO 45 DEGREES, NOT THE
BIGGEST RANGE. HOWEVER, THE STRONG JET ENERGY SHOULD BE ABLE TO
MIX WINDS DOWN FROM ALOFT. IN ADDITION, THE FAIRLY STRONG MID
LEVEL WIND, STEERING FLOW WILL BE FAIRLY HIGH AND FORWARD SPEED
OF THE STORMS WILL AID IN THE WIND. AND THERE IS STILL THE RISK
OF DRY MICROBURSTS. WE DO HAVE A CONDITIONAL INTENSITY GROUP 1
FOR THUNDERSTORM WIND (GUSTS TO 75 MPH) FROM THE EASTERN GREEN
RIVER BASIN THROUGH MOST OF THE BIGHORN BASIN AND INTO JOHNSON
COUNTY. AS FOR LARGE HAIL, THE THREAT IS SOMEWHAT LESS. MUCH OF
THE AREA, EXCEPT FOR FAR SOUTHEASTERN PARTS OF THE AREA, HAVE A
MARGINAL RISK OF THIS THOUGH. THE ATMOSPHERE EAST OF THE DIVIDE
REMAINS DRIER THAN EARLIER IN THE WEEK, SO THE RISK IS LOWER.
THE HIGHEST RISK OF HAIL WOULD BE ACROSS THE WESTERN MOUNTAINS
WHERE DEEPER MOISTURE WOULD BE FOUND. SHEAR IS SOMEWHAT LIMITED
THOUGH. HOWEVER, WITH LOW WET BULB ZERO LEVELS, SMALL HAIL IS A
GREATER POSSIBILITY HERE. ANY STORM COULD HAVE SOME HAIL, BUT
THIS IS THE LESSER THREAT. AS FOR HEAVY RAIN. PRECIPITABLE WATER
LEVELS ARE NOT THAT HIGH FOR MOST LOCATIONS. THE BEST CHANCE
WOULD BE IN THE WESTERN MOUNTAINS AND IN NORTHERN WYOMING, WHERE
PRECIPITABLE WATER LEVELS WOULD BE HIGHER BUT NOTHING EXTREME.
MOST CONVECTION SHOULD END THIS EVENING AS THE SHORTWAVE LIFTS
NORTHWARD, BUT A FEW WILL LINGER THROUGH THE NIGHT, ESPECIALLY
IN WESTERN WYOMING.
FIRE WEATHER...THIS WILL MAINLY BE A CONCERN FOR SOUTHERN AND
EASTERN WYOMING. RELATIVE HUMIDITY WILL BE A BIT HIGHER AND
TEMPERATURES A BIT COOLER THAN YESTERDAY. HOWEVER, ELEVATED FIRE
WEATHER IS STILL POSSIBLE IN THE AFTERNOON ACROSS PORTIONS OF
SWEETWATER, FREMONT, HOT SPRINGS, WASHAKIE, NATRONA AND SOUTHERN
JOHNSON COUNTIES WHERE HUMIDITY WILL FALL UNDER 25 PERCENT AND
WIND GUSTS OVER 25 MPH WILL BE COMMON THIS AFTERNOON. THE AREA
OF MOST CONCERN IS NATRONA COUNTY, WHERE HUMIDITY WILL FALL INTO
THE TEENS. IT DOESN'T QUITE LOOK LIKE RED FLAG CONDITIONS, BUT
AN HOUR OR TWO OF CRITICAL FIRE WEATHER HAS ABOUT A 1 IN 2
CHANCE THIS AFTERNOON. CONTINUED ELEVATED FIRE WEATHER IS
POSSIBLE AGAIN ON SUNDAY AFTERNOON ALTHOUGH COOLER TEMPERATURES
MAY MITIGATE THE THREAT SOMEWHAT.
COLDER TEMPERATURES AND SNOW...TEMPERATURES WILL BE COOLER ACROSS
THE ENTIRE AREA, WITH AN EMPHASIS ON WESTERN WYOMING WHERE JACKSON
WILL LIKELY BE CLOSE TO 20 DEGREES COLDER THAN FRIDAY AFTERNOON. THE
COOLEST DAY ACROSS THE AREA LOOKS TO BE SUNDAY, AS MORE CLOUD COVER
LINGERS ACROSS THE AREA AND COOLER AIR MOVES IN BEHIND A COLD FRONT.
NOW, THE MAIN THING PEOPLE ARE WONDERING ABOUT, THE CHANCE OF SNOW.
CHANCES OF THIS REALLY BEGIN TONIGHT AS COOLER AIR MOVES IN AND
700 MILLIBAR TEMPERATURES DROP DOWN TO MINUS 3C, WHICH COULD
LOWER SNOW LEVELS TO 7000 TO 8000 FEET. ANY SNOW AT THIS TIME
WOULD BE LIGHT THOUGH. OCCASIONAL LIGHT SNOW CONTINUES IN THE
MOUNTAINS THROUGH SUNDAY AND POSSIBLY INTO MONDAY. THE HEAVIEST
MAY BE MONDAY AS THE LOW LIFTS NORTH AND A TROUGH AXIS SWINGS
ACROSS THE AREA. THROUGH MONDAY, THE NBM ENSEMBLE GIVES A
GREATER THAN 2 OUT OF 3 CHANCE OF AN INCH OR MORE OF SNOW ABOVE
9000 FEET. A FEW LOCATIONS, LIKE SOUTHWESTERN YELLOWSTONE PARK,
THE HIGHEST ELEVATIONS OF THE TETONS AND WIND RIVERS ABOVE 10000
FEET HAVE A GREATER THAN 1 IN 3 CHANCE OF 4 INCHES OR MORE. IT
SHOULDN'T BE A PROBLEM FOR TRAVEL, BUT PEOPLE VENTURING INTO
THE MOUNTAINS SHOULD PREPARE FOR COOL AND WET WEATHER, THIS
INCLUDES YELLOWSTONE PARK. IF IT GETS A BIT COLDER, I CAN'T RULE
OUT SOME SNOWFLAKES INTO EVEN INTO THE JACKSON VALLEY, ALTHOUGH
NO ACCUMULATION IS EXPECTED. AND THERE IS ONE MORE THING, THE
POTENTIAL FOR FROST. IT WILL TURN MUCH COLDER TONIGHT IN THE
WEST, BUT CLOUD COVER SHOULD KEEP MOST TEMPERATURES ABOVE
FREEZING. THINGS GET A LITTLE COOLER AGAIN SUNDAY, BUT AGAIN
CLOUD COVER MAY KEEP THINGS WARMER. THE REAL DAY OF CONCERN MAY
BE MONDAY NIGHT, WHEN THE LOW LIFTS OUT AND THE SKY CLEARS.
ENSEMBLE GUIDANCE GIVES A GREATER THAN 1 IN 2 CHANCE OF LOW
TEMPERATURES 32 OR LOWER IN PLACES LIKE THE GREEN RIVER BASIN,
SOUTHERN LINCOLN COUNTY AND EVEN PORTIONS OF THE JACKSON AND
STAR VALLEYS. WE COULD SEE SOME RECORD LOWS ON THESE DAYS. IT IS
TOO EARLY FOR FREEZE HIGHLIGHTS, BUT WE WILL HAVE TO WATCH
THIS.
OTHERWISE, COOL WEATHER WILL LAST THROUGH MONDAY AND POSSIBLY
TUESDAY. WITH DECREASING INSTABILITY ON SUNDAY, THE CHANCE OF
THUNDERSTORMS WILL BE MUCH LESS. CYCLONIC CURVATURE REMAINS OVER
THE AREA ON MONDAY AS WELL, KEEPING TEMPERATURES COOL WITH MOST
PRECIPITATION CHANCES ACROSS THE NORTH AND WEST WITH DRIER
CONDITIONS FURTHER SOUTH. GOING INTO NEXT WEEK AS WE HEAD INTO
JULY, WE WILL SEE RIDGING SLOWLY BUILD INTO THE AREA WITH
TEMPERATURES GRADUALLY WARMING TO NEAR TO ABOVE NORMAL, WITH
THE WARMEST TEMPERATURES IN EASTERN PORTIONS OF THE FORECAST
AREA. WYOMING WILL BE STUCK BETWEEN A TROUGH OVER THE WESTERN
UNITED STATES AND STRONG RIDGING OVER THE EAST. THAT MEANS
UNSETTLED WEATHER IS LIKELY TO CONTINUE WITH SHORTWAVES TOPPING
THE RIDGE FROM TIME TO TIME, CHANCES OF CONVECTION AND BREEZY TO
OCCASIONALLY WINDY CONDITIONS. THERE IS A LOT OF SPREAD IN
GUIDANCE IN THE TIMING OF THE WAVES, SO CONFIDENCE IN TIMING
THE PERIODS OF SHOWERS AND STORMS REMAINS LOW AT THIS TIME.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1000 PM MDT SAT JUN 27 2026
CONVECTION HAS PRIMARILY ENDED ACROSS THE AREA. AN AREA OF
SHOWERS WILL DEVELOP VCTY KRKS AND INTO CENTRAL PORTIONS OF THE
FORECAST AREA BY 09Z, ENDING A HOUR OR TWO AFTER SUNRISE.
OTHERWISE, PRECIPITATION WILL BE CONFINED TO FAR NORTHWESTERN
PORTIONS OF THE STATE THROUGH THE DAY SUNDAY. THE STRONGER WINDS
FROM EARLIER THIS AFTERNOON HAVE SUBSIDED, WITH SUSTAINED WINDS
15KT OR LESS EXPECTED FOR ALL TERMINALS THROUGH 12Z. WEST TO
SOUTHWEST WINDS WILL INCREASE AGAIN ACROSS THE AREA, STARTING BY
12Z AT KCPR. GUSTS OF 20 TO 35KT WILL IMPACT ALL TERMINALS
THROUGH THE DAY. A LINE OF SHOWERS WILL REDEVELOP FROM KRKS TO
KBYG BETWEEN 03Z AND 06Z MONDAY AND LOOK TO STAY EAT OF KRIW,
KLND AND KWRL.
MOUNTAIN OBSCURATIONS WILL BE IN PLACE OVER THE WESTERN AND
NORTHERN MOUNTAINS TONIGHT, BECOMING CONFINED OVER FAR
NORTHWESTERN PORTIONS BY 18Z.
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 227 AM MDT SAT JUN 27 2026
ELEVATED FIRE WEATHER REMAINS LIKELY, ROUGHLY ALONG AND EAST OF
A ROCK SPRINGS TO RIVERTON TO WORLAND TO KAYCEE LINE. RELATIVE
HUMIDITY WILL FALL BELOW 25 PERCENT WITH THE LOWEST HUMIDITY IN
NATRONA COUNTY, WHERE IT WILL FALL INTO THE TEENS. A GUSTY WIND
WILL DEVELOP THIS AFTERNOON WITH WIND GUSTS TO 30 MPH, AND IN
SOME LOCATIONS, OVER 40 MPH THIS AFTERNOON. LIGHTNING STRIKES
FROM THUNDERSTORMS ARE ALSO POSSIBLE. ELEVATED FIRE WEATHER MAY
CONTINUE TOMORROW AS GUSTY WIND AND LOW HUMIDITY CONTINUES
ALTHOUGH COOLER TEMPERATURES MAY MITIGATE CONDITIONS SOMEWHAT.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...WITTMANN
DISCUSSION...HATTINGS
AVIATION...LAVOIE
FIRE WEATHER...HATTINGS
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