691
FXUS65 KRIW 200125
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
725 PM MDT FRI JUN 19 2026
KEY MESSAGES
- A FEW SHOWERS ARE STILL POSSIBLE AROUND BUFFALO AND AROUND
CASPER MOUNTAIN THIS EVENING. ANY PRECIP WILL CONTINUE HAVE
DIFFICULTY EVEN REACHING THE GROUND.
- AN APPROACHING DISTURBANCE LOOKS TO BRING WIDESPREAD CHANCES
FOR SHOWERS AND THUNDERSTORMS OVER THE WEEKEND. THE BEST
CHANCES FOR A WETTING RAIN REMAIN OVER THE NORTHERN HALF OF
THE FORECAST AREA.
- THE FIRST WEEK OF SUMMER IS LOOKING WARM WITH DAILY CHANCES
FOR SHOWERS AND THUNDERSTORMS.
UPDATE
ISSUED AT 1212 PM MDT FRI JUN 19 2026
THE FORECAST REMAINS MOSTLY ON TRACK FOR THE REST OF THE DAY
TODAY. THE MAIN FOCUS TURNS TO THE UPCOMING WEEKEND WHERE
CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN TO THE REGION. AS
MENTIONED IN THE PREVIOUS DISCUSSION, AN INITIAL PUSH OF SHOWERS
WILL WORK ITS WAY ACROSS THE STATE SATURDAY MORNING. CURRENTLY,
CAMS ARE SHOWING THIS BOUNDARY STALL OVER PORTIONS OF NATRONA,
JOHNSON COUNTIES AND POSSIBLY THE EASTERN BIGHORN BASIN.
LOCATIONS AHEAD OF THIS BOUNDARY WILL SEE INCREASED MOISTURE
WITH DEWPOINTS REACHING THE UPPER 40S TO LOW 50S, WHILE THOSE
BEHIND IT REMAIN DRIER. THE LOCATION OF THIS BOUNDARY WILL BE
KEY IN DETERMINING WHERE THE BEST INSTABILITY WILL DEVELOP.
ANOTHER CAVEAT WILL BE HOW MUCH SUNSHINE CAN BREAK THROUGH
LINGERING CLOUD COVER DURING THE LATE MORNING AND EARLY
AFTERNOON SATURDAY.
OVERALL, THERE LOOKS TO BE WIDESPREAD CHANCES (20-40% FOR
SOUTHERN WY AND 30-70% FOR CENTRAL AND NORTHERN WY) FOR SHOWERS
AND THUNDERSTORMS THROUGHOUT THE DAY SATURDAY. THE FIRST PUSH
ARRIVES IN THE EARLY MORNING HOURS SATURDAY AND WILL LIKELY BE
IN THE FORM OF LIGHT SHOWERS WITH MAYBE AN ISOLATED RUMBLE OF
THUNDER. A BRIEF BREAK IS EXPECTED BY THE LATE MORNING AND EARLY
AFTERNOON HOURS, WHERE SOME SUNSHINE SHOULD BE ABLE TO BREAK
THROUGH DECREASING CLOUD COVER. THE EARLY AFTERNOON WILL SEE
CONVECTION BEGIN TO INITIATE OFF THE HIGHER ELEVATIONS AND
GRADUALLY SPREAD EAST/NORTHEAST. THE MAIN CONCERN FOR THE
MAJORITY OF THE FORECAST AREA WILL BE STRONG GUSTY OUTFLOW WINDS
AND FREQUENT LIGHTNING. HI-RES MODELS DO INDICATE STRONG
OUTFLOWS POSSIBLY IN EXCESS OF 50 MPH SPREADING ACROSS THE
FORECAST AREA THROUGH THE AFTERNOON HOURS SATURDAY. DRY
THUNDERSTORMS AND VIRGA SHOWERS WILL BE POSSIBLE, ESPECIALLY
ACROSS SOUTHERN WY WHERE THE ATMOSPHERE LOOKS TO BE DRIER.
HOWEVER, LOCATIONS AHEAD OF THE BOUNDARY MAY SEE SOME STRONG
STORMS DEVELOP. THE FAVORED LOCATIONS WOULD BE JOHNSON AND
NATRONA COUNTIES WHERE THE GREATEST INSTABILITY LOOKS TO BE.
THAT BEING SAID, A STRONG STORM OR TWO CANNOT BE RULED OUT
ACROSS PORTIONS OF THE WIND RIVER AND THE BIGHORN BASINS. AS FOR
JOHNSON AND NATRONA COUNTIES, STRONG GUSTY OUTFLOWS IN EXCESS
OF 50 MPH, FREQUENT LIGHTNING, PERIODS OF MODERATE RAIN AND
SMALL HAIL LOOK TO BE THE MAIN HAZARDS IN ASSOCIATION WITH ANY
STRONG STORMS THAT DO DEVELOP. STORMS SHOULD WEAKEN OR MOVE OUT
OF THE FORECAST AREA BY SUNSET. A FEW LINGERING SHOWERS WILL BE
POSSIBLE MAINLY OVER CENTRAL AND NORTHERN WY THROUGH THE
OVERNIGHT HOURS INTO SUNDAY MORNING.
DISCUSSION
ISSUED AT 230 AM MDT FRI JUN 19 2026
A RIDGE WILL BUILD OVER THE REGION FROM THE WEST TODAY, AS PACIFIC
MOISTURE BEGINS TO ENTER THE REGION. HIGHS THIS AFTERNOON WILL BE IN
THE 70S AND 80S, WITH READINGS APPROACHING THE 90 DEGREE MARK OVER
THE WESTERN HALF OF SWEETWATER COUNTY. WINDS WILL NOT BE AS STRONG
TODAY AS THE SFC PRESSURE GRADIENT LOOSENS AND THE RIDGE AXIS SHIFTS
OVER THE COWBOY STATE. WEST WINDS, WITH GUSTS UP TO 25 MPH, WILL
DEVELOP OVER AREAS WEST OF THE DIVIDE BY MID-AFTERNOON AND DECREASE
IN THE EVENING. AT THE SAME TIME, ANOTHER SURGE OF EASTERLY WINDS
WILL OCCUR OVER NATRONA COUNTY INTO THE WIND RIVER BASIN, WITH GUSTS
OF 25 TO 35 MPH OCCURRING THROUGH 08Z. ELEVATED TO CRITICAL FIRE
WEATHER CONDITIONS WILL ALSO RETURN ACROSS SOUTHERN PORTIONS OF THE
FORECAST AREA, DUE TO THE AFOREMENTIONED WINDS AND HUMIDITY VALUES
AS LOW AS 8%. VIRGA SHOWERS WILL BE POSSIBLE ACROSS THE CWA THROUGH
THE AFTERNOON INTO THE EARLY EVENING. BRIEF GUSTS OF 50 TO 60 MPH
COULD OCCUR FROM THESE SHOWERS, DUE TO THE LARGE DEWPOINT SPREADS
THAT WILL BE PRESENT. ANOTHER AREA OF VIRGA SHOWERS WILL DEVELOP
OVER FAR WESTERN PORTIONS AFTER 06Z SATURDAY, MOVING EAST OF THE
DIVIDE BY THE PREDAWN HOURS SATURDAY MORNING. THIS WILL BE A
PRECURSOR TO THE MORE WIDESPREAD CONVECTIVE ACTIVITY EXPECTED
DURING THE DAY SATURDAY.
CHANCES FOR PRECIPITATION RETURN FOR THE WEEKEND, AS A REMNANT
PACIFIC LOW MOVES OVER THE REGION. NORTHERN PORTIONS OF THE CWA
CONTINUE TO HAVE THE BEST CHANCES TO RECEIVE ANY PRECIPITATION, WITH
FORECASTED RAINFALL AMOUNTS TRENDING DOWNWARDS AGAIN (NO SURPRISE).
AMOUNTS ARE NOW IN THE 0.20" TO 0.40" RANGE SATURDAY THROUGH MONDAY,
WITH PORTIONS OF NATRONA COUNTY TRENDING ABOVE 0.10". LOCALLY HEAVY
RAIN REMAINS POSSIBLE FROM THESE STORMS, AS PRECIPITABLE WATER
VALUES OF 0.60" TO 1" ARE STILL FORECASTED. PRECIPITATION CHANCES
LINGER INTO MONDAY, AS A CANADIAN COLD FRONT MOVES OVER AREAS EAST
OF THE DIVIDE. DRY CONDITIONS RETURN TO THE REGION TUESDAY, AS A
STRONG AREA OF HIGH PRESSURE DEVELOPS OVER THE DESERT SOUTHWEST.
MODELS REMAIN SPLIT WHETHER SHORTWAVES WILL MOVE OVER THE
PACNW/NORTHERN ROCKIES FROM WEDNESDAY TO FRIDAY, KEEPING
PRECIPITATION CHANCES UP AND THE RIDGE SUPPRESSED TO THE SOUTH.
GIVEN THE LATEST CPC OUTLOOKS OF A 33% CHANCE FOR ABOVE NORMAL
PRECIPITATION, CONFIDENCE IS LOW TO MEDIUM AT THIS TIME.
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 349 PM MDT FRI JUN 19 2026
VFR CONDITIONS PREVAIL THROUGH THE NEXT 24 HOURS, THOUGH SHOWERS AND
THUNDERSTORMS SATURDAY AFTERNOON MAY BRING BRIEF MVFR TO POSSIBLY IFR
CONDITIONS IF MODERATE TO HEAVY RAIN OCCURS. GUSTY WINDS FROM THIS
AFTERNOON GENERALLY DECREASE THROUGH THE EVENING. AN EASTERLY PUSH
OF WIND BRINGS GUSTS 15 TO 25 KNOTS AT KCPR AND KRIW THROUGH ABOUT
08Z. A PASSAGE OF VERY LIGHT SHOWERS AND VIRGA SHOWERS OCCUR THOUGH
12Z TONIGHT, MOVING FROM THE SOUTHWEST TO NORTHEAST DURING THOSE 12
HOURS OR SO. GUSTY OUTFLOW WINDS ARE POSSIBLE, BUT GENERALLY NO
IMPACTS ARE EXPECTED; KRKS WOULD BE THE MOST LIKELY TO SEE IMPACTS,
IF ANY. SHOWERS AND THUNDERSTORMS BECOME WIDESPREAD STARTING AROUND
18Z SATURDAY, WITH CHANCES THROUGH THE THE END OF THE TAF PERIOD.
VARIABLE GUSTY OUTFLOW WINDS 40 TO 50 KNOTS IS THE MOST LIKELY
HAZARD, THOUGH SMALL HAIL IS ALSO POSSIBLE, MAINLY AROUND KCPR.
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.
UPDATE...DZIEWALTOWSKI
DISCUSSION...LAVOIE
AVIATION...WITTMANN
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