663
FXUS65 KRIW 080458
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1058 PM MDT TUE JUL 7 2026
KEY MESSAGES
- SHOWERS AND STORMS HAVE PRIMARILY ENDED ACROSS THE FORECAST
AREA THIS EVENING. ANY ADDITIONAL SHOWERS AND STORMS WILL BE
VERY ISOLATED THROUGH THE NIGHT.
- WEDNESDAY WILL SEE ANOTHER ROUND OF AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS WITH NEAR SEASONABLE TEMPERATURES.
STRONG STORMS ARE POSSIBLE OVER JOHNSON COUNTY LATE WEDNESDAY
AFTERNOON. SHOWERS WILL AGAIN LINGER WEDNESDAY NIGHT INTO
THURSDAY MORNING OVER SOME AREAS.
- ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AGAIN THURSDAY
AFTERNOON OVER CENTRAL WY, AND PERHAPS FRIDAY AFTERNOON ACROSS
WESTERN WY. TEMPERATURES BEGIN TO CLIMB ON FRIDAY TO 5-10
DEGREES ABOVE NORMAL.
- VERY WARM TO HOT TEMPERATURES ARE EXPECTED THIS WEEKEND ALONG
WITH DRY CONDITIONS. RECORD-BREAKING TEMPERATURES ARE POSSIBLE
SATURDAY, SUNDAY, AND MONDAY, WITH MID 90S IN THE WESTERN
VALLEYS, AND 100 TO 105 DEGREES IN THE BASINS EAST OF THE
DIVIDE.
UPDATE
ISSUED AT 1245 PM MDT TUE JUL 7 2026
AS I WROTE IN A COUPLE OF DISCUSSIONS LAST WEEK ABOUT THIS SAME
TIME OF DAY, ANOTHER SHORTWAVE TROUGH IS MOVING FROM THE
NORTHEAST GREAT BASIN THROUGH WY. MOISTURE IS AMPLE WITH
SURFACE DEWPOINTS RANGING FROM THE LOW 40S TO THE MID 50S AND
PRECIPITABLE WATER VALUES AROUND TWO-THIRDS TO THREE-QUARTERS OF
AN INCH. BASED ON THE RIW 18Z SOUNDING (STILL IN FLIGHT), AS
TEMPERATURES REACH AROUND 90F, CAPE AROUND 1000 J/KG WILL ALLOW
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP AND
CONTINUE THROUGH THE AFTERNOON AND INTO THE EVENING. AS OF 1210
PM, CONVECTION HAS ALREADY INITIATED IN THE UPPER GREEN RIVER
BASIN AND NEAR COKEVILLE AND FLAMING GORGE, MOVING ENE TODAY.
THE AREA FROM SOUTHWEST WY TOWARD CENTRAL WY AND INTO JOHNSON
COUNTY WILL HAVE THE HIGHER PROBABILITIES OF THUNDERSTORMS
TODAY, WITH GUSTY OUTFLOW WINDS OF 40-50 MPH THE PRIMARY THREAT,
ESPECIALLY IN AREAS WHERE THE DEWPOINT DEPRESSIONS ARE LARGER.
BRIEF HEAVY RAIN EVEN FROM HIGHER CLOUD BASES AND SMALL(ISH)
HAIL WILL ALSO OCCUR WITH FREQUENT LIGHTNING. SPC MAINTAINS A
SLIGHT RISK OF SEVERE STORMS FOR NORTHEAST WY, SO STORMS THAT
DEVELOP AROUND JOHNSON COUNTY FROM 5 TO 8 PM HAVE A HIGHER
CHANCE OF PRODUCING SEVERE CONVECTIVE WEATHER. CAMS AND
MESOSCALE MODELS CONTINUE TO SHOW AREAS OF SHOWERS THROUGH
MIDNIGHT ACROSS MUCH OF WESTERN AND CENTRAL WY TOO.
THE GENERAL INSTABILITY AND INCREASED BOUNDARY LAYER MOISTURE
CONTINUES INTO WEDNESDAY FOR MORE ISOLATED SHOWERS AND
THUNDERSTORMS DURING THE AFTERNOON. GUSTY OUTFLOW WINDS WILL BE
THE PRIMARY THREAT, WITH STRONGER STORMS EXPECTED YET AGAIN OVER
JOHNSON COUNTY.
DISCUSSION
ISSUED AT 328 AM MDT TUE JUL 7 2026
A FEW SHOWERS AND THUNDERSTORMS CONTINUE TO LINGER ACROSS THE STATE
EARLY THIS MORNING. AS OF WRITING THIS AROUND 0100 MDT, A COUPLE
FLASHES OF LIGHTNING HAVE BEEN DETECTED OVER PORTIONS OF WESTERN WY.
HOWEVER, CONVECTIVE ACTIVITY IS GRADUALLY WANING WITH CLUSTERS OF
LIGHTNING CONTINUING TO DECREASE. PRECIPITATION CHANCES WILL REMAIN
MOSTLY ACROSS WESTERN AND NORTHERN WY THROUGH THE PREDAWN HOURS.
SHOWERS AND STORMS WILL CONTINUE TO TREK EAST THROUGH THE MORNING
WITH THE BULK DISSIPATING BY SUNRISE.
A SHORTWAVE WILL BE THE MAIN INSTIGATOR FOR THE "ACTIVE" WEATHER
TODAY AND WEDNESDAY. THE SHORTWAVE CURRENTLY IS MAKING ITS WAY
ACROSS MONTANA WHILE USHERING IN ABOVE NORMAL MOISTURE TO THE
REGION. THIS CAN BE SEEN WITH PWATS BEING NEARLY 100-150% ABOVE
NORMAL ACROSS MUCH OF THE AREA. DEWPOINTS ALSO REFLECT THIS WITH
PORTIONS OF THE BIGHORN BASIN AND JOHNSON COUNTY LIKELY TO SEE
VALUES IN THE 50S THIS AFTERNOON. AS FOR TEMPERATURES, THEY WILL BE
SIMILAR TO MONDAY WITH HIGHS IN THE UPPER 80S TO LOWER 90S EAST
OF THE DIVIDE AND LOW TO MID 80S WEST OF THE DIVIDE. SCATTERED
SHOWERS AND THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE LATER THIS
AFTERNOON AND EVENING. COVERAGE TODAY WILL SHIFT FARTHER SOUTH
WITH NORTHWESTERN WY LIKELY HAVING LESSER CHANCES OF SEEING A
SHOWER OR STORM COMPARED TO ELSEWHERE. PRECIPITATION CHANCES
ACROSS THE FORECAST AREA ASIDE FROM NORTHWESTERN WY LOOK TO
RANGE FROM 20-40% WITH THE BEST CHANCES BEING OVER CENTRAL AND
PORTIONS OF SOUTHERN WY.
THE OTHER ASPECT REGARDING THE CONVECTION POSSIBLE THIS AFTERNOON
AND EVENING, WILL BE THE POTENTIAL FOR A FEW STRONG TO SEVERE STORMS
DEVELOPING. THE STORM PREDICTION CENTER HAS HIGHLIGHTED MUCH OF THE
STATE WITH A MARGINAL RISK (1 OUT OF 5). THE ONLY EXCEPTION TO THIS
IS PORTIONS OF NORTHWESTERN AND WESTERN WY, SPECIFICALLY MUCH OF YNP
AND THE TETONS/JACKSON HOLE WHERE THE MARGINAL RISK HAS BEEN
EXCLUDED. THERE IS A VERY SMALL SLIVER OF SLIGHT RISK (2 OUT OF 5)
FOR A PORTION OF JOHNSON COUNTY MAINLY DUE TO LARGE HAIL THREAT. THE
SETUP IS A WIDE SWATH OF ABOVE NORMAL MOISTURE ACROSS THE AREA.
MORNING CLOUD COVER IS EXPECTED TO GRADUALLY CLEAR BY THE EARLY
AFTERNOON WITH DAYTIME HEATING HELPING PRODUCE CAPE VALUES AROUND
500 J/KG OVER MUCH OF THE STATE. SOME CAMS ARE HIGHLIGHTING PORTIONS
OF JOHNSON COUNTY AND CENTRAL WY WITH SWATHS OF CAPE NEARING 1000
J/KG. SO IF THIS WERE TO OCCUR, THERE COULD BE MORE JUICE FOR ANY
STORMS THAT DEVELOP. STEEP LOW TO MID LEVEL LAPSE RATES ARE FORECAST
OVER MUCH OF THE STATE AS WELL. THE OTHER FACTOR WILL BE FAVORABLE
DYNAMICS AS A RESULT OF THE NEARBY SHORT WAVE. LOW TO MID LEVEL WIND
SHEAR VALUES CURRENTLY LOOK TO RANGE FROM 25 TO 35 KNOTS. OVERALL,
THE MAIN THREAT TODAY WILL BE STRONG GUSTY WINDS WITH CAMS
HIGHLIGHTING FAVORABLE DOWNDRAFT CAPE VALUES. STORMS COULD
PRODUCE STRONG GUSTY OUTFLOW WINDS OF 50 MPH OR MORE AT TIMES.
THERE DOES REMAIN A THREAT FOR HAIL WITH THE MOST FAVORABLE
LOCATIONS BEING CENTRAL AND NORTHERN WY, SPECIFICALLY JOHNSON
COUNTY. OTHERWISE, FREQUENT LIGHTNING AND BRIEF MODERATE
RAINFALL MAY BE POSSIBLE WITH ANY STORMS. SHOWERS AND
THUNDERSTORMS MAY LINGER INTO THE LATE EVENING HOURS TUESDAY AND
POSSIBLY INTO THE EARLY MORNING HOURS WEDNESDAY.
WEDNESDAY HAS TRENDED TOWARDS ANOTHER DAY WITH POSSIBLE AFTERNOON
SHOWERS AND THUNDERSTORMS. THIS ONCE AGAIN IS THE RESULT OF
LINGERING MOISTURE AND THE EXITING SHORTWAVE. CURRENTLY, MUCH OF THE
STATE LOOKS TO HAVE SIMILAR CHANCES FOR PRECIPITATION AS TUESDAY.
HOWEVER, CHANCES FOR STRONG TO SEVERE STORMS LOOKS TO DIMINISH AND
SHIFT FARTHER EAST. THE SPC CURRENTLY HAS FAR EASTERN PORTIONS OF
JOHNSON AND NATRONA COUNTIES IN A MARGINAL RISK WITH THE MAIN
CONCERNS BEING STRONG GUSTY WINDS AND HAIL. ASIDE FROM THESE
LOCATIONS, THE REMAINDER OF THE STATE WILL SEE SIMILAR HAZARDS AS
THE PREVIOUS DAYS WITH FREQUENT LIGHTNING, GUSTY WINDS, AND SMALL
HAIL POSSIBLE.
NO, THERE DOES NOT SEEM TO HAVE BEEN A TECHNICAL GLITCH IN THE LONG
TERM FORECAST MODELS, IT REALLY IS LOOKING TO BE THAT HOT THIS
WEEKEND. SOME LONG TERM MODELS HAVE DONE A GOOD JOB OF INDICATING
THIS HEAT AS EARLY AS LAST WEEK. BARRING SOME MIRACULOUS SHIFT IN
THE WEATHER PATTERN, WE ARE LIKELY TO SEE A PERIOD OF DANGEROUSLY
HOT, RECORD BREAKING TEMPERATURES THIS WEEKEND. THIS HEAT WILL BE
THE RESULT OF AN ANOMALOUSLY POTENT HIGH PRESSURE RIDGE THAT BUILDS
ACROSS THE WESTERN/CENTRAL CONUS. TEMPERATURES START TO TURN UP
FRIDAY WITH CURRENT HIGHS GETTING INTO THE MIDDLE TO UPPER 90S
EAST OF THE DIVIDE AND UPPER 80S TO LOWER 90S WEST OF THE
DIVIDE. THE WARMEST TEMPERATURES LOOK TO ARRIVE FOR THE WEEKEND.
GUIDANCE IS SHOWING WESTERN VALLEYS SUCH AS STAR VALLEY AND
JACKSON HOLE POSSIBLY SEEING HIGHS AROUND 95F SATURDAY.
LOCATIONS EAST OF THE DIVIDE TO NO SURPRISE ARE WARMER, WITH
CENTRAL BASINS SEEING HIGHS NEARING THE CENTURY MARK. NORTHERN
LOCATIONS, SUCH AS PORTIONS OF THE BIGHORN BASIN MAY SEE HIGHS
NEARING 105F. SUNDAY LOOKS EVEN WARMER WITH LOCATIONS WEST OF
THE DIVIDE SEEING 20-40% OF HIGHS NEARING 100F. EAST OF THE
DIVIDE CENTRAL BASINS HAVE 20-50% FOR HIGHS AROUND 105F.
PORTIONS OF THE BIGHORN BASIN MAY SEE HIGHS NEAR 110F WITH
CHANCES SITTING AROUND 10-30%. THESE PERCENTAGES ARE TO SHOW THE
POTENTIAL RANGE FOR HIGH TEMPERATURES. SO IF THERE IS A 20-50%
FOR HIGHS NEAR 105F, ITS LIKELY THE HIGHS WILL AT LEAST BE
GREATER THAN 100F. THERE IS INCREASING LIKELIHOOD THAT NUMEROUS
DAILY HIGH TEMPERATURE RECORDS AND EVEN ALL-TIME HIGH
TEMPERATURE RECORDS MAY BE MET OR BROKEN. CLIMATE DATA AT KLND
GOES BACK TO 1891 AND THE CURRENT ALL TIME HIGH TEMPERATURE IS
102F SET BACK IN 1935 ON JULY 27TH. CURRENTLY, THE NBM HAS A
FORECAST HIGH OF 104F FOR SUNDAY, SO THAT SHOULD GIVE AN IDEA OF
HOW HISTORIC THIS PERIOD OF HEAT MAY BE. YES, THIS DEGREE OF
HEAT CAN BE DANGEROUS FOR THOSE WHO ARE AT RISK OR DO NOT USE
CAUTION. SO BE SURE TO STAY UP TO DATE ON THE FORECAST AND BE
PREPARED, ESPECIALLY IF PLANNING OUTDOOR ACTIVITIES!
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1058 PM MDT TUE JUL 7 2026
PREVAILING VFR CONDITIONS THROUGH THE TAF PERIOD. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP WEDNESDAY
AFTERNOON. COVERAGE WILL BE LESS THAN TUESDAY AFTERNOON. WESTERN
TERMINALS (KJAC, KBPI, KPNA) SHOULD MISS OUT ON MOST OF THE
CONVECTION WEDNESDAY AFTERNOON AND EVENING, ALTHOUGH THERE IS
STILL A LOW CHANCE (AROUND 10-15%). MOST TERMINALS HAVE PROB30
GROUPS FOR -TSRA AND STRONG VRB WIND. CONDITIONS MAY DROP AS
LOW AS IFR IN THE STRONGEST STORMS IF THEY MOVE DIRECTLY OVER A
TERMINAL. ISOLATED RAIN SHOWERS WILL MOVE THROUGH SOUTHERN
PORTIONS OF THE AREA, WITH SOME SHOWERS IN THE VICINITY OF KRKS
OVERNIGHT AND EARLY WEDNESDAY MORNING.
WIND WILL BE LIGHT TONIGHT INTO WEDNESDAY MORNING. WIND SHOULD
BECOME BREEZY (10-15 KNOTS) WEDNESDAY AFTERNOON, BUT WILL BE QUITE
VRB DUE TO NUMEROUS OUTFLOW BOUNDARIES FROM SHOWERS AND STORMS.
ISOLATED WIND GUSTS TO 50 KNOTS ARE POSSIBLE WITH THE STRONGEST
STORMS WEDNESDAY AFTERNOON.
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...MCDONALD
DISCUSSION...DZIEWALTOWSKI
AVIATION...ROWE
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