891
FXUS65 KRIW 121120
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
520 AM MDT SUN APR 12 2026
KEY MESSAGES
- MORE OF THE SAME TODAY WITH ELEVATED FIRE WEATHER IN CENTRAL
WYOMING AND SOME SHOWERS AND STORMS IN WESTERN WYOMING. THE
MAIN THREAT FROM ANY STORM IS WIND GUSTS PAST 50 MPH.
- SHOWERS AND STORM COVERAGE DROPS MONDAY. ELEVATED TO POSSIBLY
CRITICAL FIRE WEATHER POSSIBLE IN CENTRAL WYOMING MONDAY
AFTERNOON.
- A POTENTIAL WET WEATHER SYSTEM MAY APPROACH FOR THE END OF THE
WEEK, WITH THE CHANCE OF A WIDESPREAD RAIN AND SNOW EVENT.
DISCUSSION
ISSUED AT 130 AM MDT SUN APR 12 2026
WE ARE NOW WELL INTO APRIL. AND THIS MEANS WE ARE NOW
CLIMATOLOGICALLY THE WETTEST TIME OF THE YEAR, THE MONTHS OF APRIL,
MAY AND JUNE. THIS IS USUALLY WHEN WE RECEIVE OUR BEST RAINS AND
MOISTURE LADEN SNOWS, TO BUILD UP THE WATER FOR THE DRIER SUMMER AND
EARLY FALL MONTHS. THESE THREE MONTHS WE RECEIVE ON AVERAGE ANYWHERE
FORM 30 TO AS MUCH AS 53 PERCENT OF OUR ANNUAL PRECIPITATION. AND WE
DEFINITELY NEED IT THIS YEAR. ONLY GREYBULL IS ABOVE NORMAL WITH
PRECIPITATION THIS YEAR. THE REMAINDER OF THE AREA IS ANYWHERE FROM
25 TO 80 PERCENT OF NORMAL. RIVERTON, LANDER, BUFFALO AND CASPER
HAVE RECEIVED LESS THAN HALF OF THE AVERAGE AMOUNT OF PRECIPITATION
THIS YEAR, WITH RIVERTON AND BUFFALO ONLY AT AROUND A QUARTER OF
NORMAL. THE GOOD NEWS IS, WE WILL HAVE A FEW CHANCES OF
PRECIPITATION THROUGH THE PERIOD.
AS I WRITE THIS AROUND 1 AM, THE RADAR IS LARGELY QUIET. TODAY WILL
BE ANOTHER DAY OF SCATTERED SHOWERS AND THUNDERSTORMS AS ANOTHER
SHORTWAVE CROSSES THE AREA. PRECIPITABLE WATERS, ESPECIALLY EAST OF
THE DIVIDE, ARE AROUND 25 PERCENT LESS THAN YESTERDAY THOUGH. SO,
THE VAST MAJORITY OF SHOWERS AND STORMS WOULD BE WEST OF THE DIVIDE
TODAY. AS FOR STRONGER STORMS, THERE IS A MARGINAL RISK ACROSS
ROUGHLY THE WESTERN THIRD OF THE AREA. AND GIVEN THE INVERTED V
SOUNDINGS ACROSS THE AREA, THE MAIN THREAT, LIKE YESTERDAY, WOULD BE
STRONG WIND GUSTS OVER 50 MPH. THERE IS ANOTHER CONCERN EAST OF THE
DIVIDE. THE 700 MILLIBAR WINDS ARE STRONGER EAST OF THE DIVIDE,
APPROACHING 40 KNOTS IN SOME LOCATIONS THIS AFTERNOON. HUMIDITY WILL
ALSO BE RATHER LOW, FALLING BELOW 20 PERCENT. HOWEVER, ENSEMBLE
FORECASTS GIVE AT MOST A 1 OUT 2 CHANCE OF RELATIVE HUMIDITY FALLING
TO 15 PERCENT OR UNDER AND ONLY FOR AN HOUR OF SO. SO, CRITICAL FIRE
WEATHER LOOKS UNLIKELY. HOWEVER, ELEVATED FIRE WEATHER LOOKS LIKELY
ACROSS MUCH OF SWEETWATER, FREMONT, NATRONA AND JOHNSON COUNTIES THIS
AFTERNOON. THERE WILL ALSO BE SOME SNOW IN THE HIGHER ELEVATIONS,
WITH THE HEAVIEST IN THE WIND RIVER RANGE. THE CHANCE OF OVER 6
INCHES IS RATHER SMALL THOUGH, AT MOST A 1 IN 3 CHANCE AND THIS OVER
THE HIGHEST ELEVATIONS WHERE IMPACTS ARE LIMITED.
THE CHANCE OF SHOWERS CONTINUES MONDAY AS WELL, ALTHOUGH SOMEWHAT
LESS MOISTURE SHOULD LEAD TO A SMALLER COVERAGE AND LARGELY WEST OF
THE DIVIDE AS WELL. CONVECTION SHOULD REACH A NADIR ON TUESDAY WITH
ONLY ISOLATED SHOWERS ACROSS THE AREA. THE ONE FLY IN THE OINTMENT
IS AN UPPER LEVEL LOW PASSING ACROSS COLORADO THAT WAS SHOWING A
DECENT AMOUNT OF QPF ACROSS SOUTHERN WYOMING. RECENT MODEL TRENDS
HAVE PUSHED THE SYSTEM FURTHER SOUTHWARD AND POPS WERE LOWERED AS A
RESULT, AT THIS TIME, ANY SHOWERS FROM THIS WOULD BE CONFINED TO THE
FAR SOUTH WITH A GREATER THAN 1 IN 3 CHANCE OF A TENTH OF AN INCH OR
RAIN CONFINED TO AREAS SOUTH OF INTERSTATE 80. TEMPERATURES THROUGH
TUESDAY AND EVEN WEDNESDAY WILL CONTINUE TO AVERAGE ABOVE NORMAL.
THEN HEADING INTO THE END OF THE WEEK, WE HAVE THE CHANCE OF
SOMETHING WE HAVE NEEDED FOR A WHILE, A CHANCE OF A DECENT
PRECIPITATION EVENT ACROSS MUCH OF THE AREA. THIS COMES COURTESY OF
AN UPPER LEVEL LOW MOVING INTO BRITISH COLUMBIA AND THEN MOVING INTO
THE NORTHERN ROCKIES FOR THURSDAY AND FRIDAY. MY GUT FEELING, GIVEN
THE FAST BIAS OF THE MODELS FOR PACIFIC SYSTEMS, IS THAT THIS WOULD
START MORE WEDNESDAY NIGHT OR THURSDAY, WITH WEDNESDAY LARGELY DRY.
THIS LOOKS TO BE A SLOWER MOVING SYSTEM WITH A GOOD AMOUNT OF
MOISTURE THAT COULD, EMPHASIS ON COULD, BRING A GOOD RAIN AND
SNOW TO MUCH OF THE AREA. THERE ARE STILL FAIRLY SUBSTANTIAL
DIFFERENCES WITH DETAILS IN REGARDS TO THE MOVEMENT OF THE UPPER
LEVEL LOW AND ANY LEE CYCLOGENESIS, AND THIS LEADS TO DIFFERENCES
IN PLACEMENT OF THE BEST UPSLOPE FLOW AND PLACEMENT OF THE
HEAVIEST PRECIPITATION. SO, I WILL NOT EVEN ATTEMPT TO PINPOINT
DETAILS THIS FAR OUT. THIS WILL BE A COOLER SYSTEM AS WELL,
WITH 700 MILLIBAR TEMPERATURES FALLING TO MINUS 10 OR LOWER,
DROPPING SNOW LEVELS TO VALLEY AND BASIN FLOORS THURSDAY NIGHT.
ENSEMBLE GUIDANCE GIVES AT LEAST A 2 OUT OF 3 CHANCE OF AT LEAST
AND INCH OF SNOW ACROSS MUCH OF THE AREA FROM THURSDAY THROUGH
FRIDAY NIGHT, WITH SIMILAR CHANCES OF AT LEAST A QUARTER OF AN
INCH OF PRECIPITATION THROUGH THE PERIOD. IT IS STILL SEVERAL
DAYS OUT BUT THINGS LOOK SOMEWHAT PROMISING RIGHT NOW, KEEP YOUR
FINGERS CROSSED.
AND THE FINAL CONCERN IS FOR A FREEZE. YES, IT IS ONLY MID APRIL NO
ONE SHOULD BE PLANTING GARDENS OR CROPS YET; LONGTIME RESIDENTS
KNOW BETTER. HOWEVER, MANY TREES HAVE BLOOMED AND MANY FLOWERS
ARE OUT. THIS COULD BE A CONCERN AS EARLY AS THURSDAY NIGHT WITH
THE SNOW. THE REAL TIME OF CONCERN MAY BE FRIDAY NIGHT,
ESPECIALLY IF THE SNOW ENDS EARLIER AND THERE IS SOME CLEARING.
EARLY ENSEMBLE GUIDANCE GIVES AT LEAST A 2 OUT OF 3 CHANCE OF
LOW TEMPERATURES BELOW 25 DEGREES IN THE LOWER ELEVATIONS BY
SATURDAY MORNING, WITH SOME AREAS HAVING A 1 IN 2 CHANCE OF LOWS
BELOW 20. A LOT DEPENDS ON HOW MUCH SNOW FALLS AND IF THERE IS
ANY CLEARING, BUT A LOT OF EARLY BLOOMING PLANTS WILL LIKELY
HAVE A TOUGH COUPLE OF NIGHTS TOWARD THE END OF THE WEEK.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 513 AM MDT SUN APR 12 2026
VFR CONDITIONS ARE GENERALLY EXPECTED THROUGH MOST OF THE NEXT
24 HOURS, BUT SHOWER ACTIVITY WILL IMPACT THIS AT TIMES THIS
AFTERNOON. KJAC WILL SEE PASSING SHOWERS AND THUNDERSTORMS
AGAIN THIS AFTERNOON, WITH VARYING CIGS AND VIS, ALONG WITH THE
POSSIBILITY OF GUSTY WINDS REACHING 40 TO 50KTS IN THE VICINITY
OF THESE STORMS. MOST OF THESE WINDS WILL BE FROM THE SOUTHWEST,
BUT MAY IMPACT FRO OTHER DIRECTIONS DURING PASSAGE. TSRA MAY
ALSO BE NEEDED AT KBPI/KPNA/KLND FOR THIS AFTERNOON, BUT
OPPORTUNITY FOR ANY RESTRICTIONS IS LOWER, SO HAVE LIMITED ANY
NOTATION IN TAFS FOR THE MOMENT. THESE SITES, ALONG WITH KRIW
AND KRKS, MAY SEE GUSTY SOUTHWEST WINDS FROM ANY STORMS THAT DO
FORM, EVEN IF THUNDERSTORMS DO NOT APPROACH THESE SITES.
CONDITIONS WILL IMPROVE AFTER SUNSET WITH LOSS OF DAYTIME
HEATING, WITH CLEAR SKIES AND LIGHT WINDS OVERNIGHT TONIGHT.
FIRE WEATHER
ISSUED AT 130 AM MDT SUN APR 12 2026
A COMBINATION OF ABOVE NORMAL TEMPERATURE, HUMIDITY FALLING TO
BETWEEN 15 AND 20 PERCENT AND A GUSTY WEST TO SOUTHWESTERLY WIND
WILL BRING ELEVATION FIRE WEATHER ROUGHLY ALONG AND EAST OF A
ROCK SPRINGS TO RIVERTON TO CASPER LINE THIS AFTERNOON. ELEVATED
FIRE TO POSSIBLY CRITICAL FIRE WEATHER IS POSSIBLE AGAIN ON
MONDAY WITH LOWER DEW POINTS AND CONTINUED GUSTY WIND, BUT
SOMEWHAT LOWER TEMPERATURES.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...HATTINGS
AVIATION...STRAUB
FIRE WEATHER...HATTINGS
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