814
FXUS65 KRIW 010254
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
854 PM MDT MON MAR 31 2025
KEY MESSAGES
- SNOW OR A RAIN/SNOW MIX REMAIN LIKELY (70-90%) TONIGHT THROUGH
WEDNESDAY. THE GREATEST SNOW ACCUMULATIONS WILL BE ACROSS THE
WESTERN MOUNTAINS WHERE A WINTER WEATHER ADVISORY REMAINS IN
EFFECT. SOME LIGHT ACCUMULATIONS ALONG EXPECTED ALONG THE I-80
CORRIDOR.
- CHANCES FOR SNOW OR A RAIN/SNOW MIX REMAIN POSSIBLE THROUGH
THE FIRST HALF OF THE WEEKEND.
UPDATE
ISSUED AT 843 PM MDT MON MAR 31 2025
SHOWERS CONTINUES TO SPREAD EAST ACROSS SOUTHWEST WYOMING
TONIGHT, WITH SNOWFALL ACCUMULATION FOCUSED ACROSS SWEETWATER
COUNTY.SNOW WILL STILL BE PRODUCED IN BANDS OVERNIGHT, SO EXPECT
VARYING CONDITIONS ALONG I-80 THROUGH THE NIGHT. TOTAL
ACCUMULATIONS REMAIN WELL BELOW ADVISORY CRITERIA, SO NO
ADJUSTMENT TO CURRENT HIGHLIGHTS.
LATEST EVENING MODEL RUNS HAVE NOTED AN INCREASE IN NW FLOW
DURING THE DAY TUESDAY ACROSS CENTRAL WY. THIS INCREASES THE
CONFIDENCE OF A BAND OF RAINFALL DOWNWIND FROM THE BIGHORN
MOUNTAINS TUESDAY AFTERNOON. THIS IS EXPECTED TO CONTINUE INTO
TUESDAY EVENING, WHEN IT WILL CHANGE TO SNOW BEFORE ENDING. HAVE
UPDATED FORECAST FOR TUESDAY TO ACCOUNT FOR INCREASE PRECIP
AMOUNTS FOR JOHNSON AND NORTHERN NATRONA COUNTIES. REMAINING
FORECAST REMAINS INTACT FOR THE EVENING.
DISCUSSION
ISSUED AT 105 AM MDT MON MAR 31 2025
BRIEF INDUCED RIDGING INTO EARLY MONDAY MORNING AS ANOTHER
PACIFIC NORTHWEST TROUGH PUSHES CLOSER. THIS WILL OPEN THE
PACIFIC MOISTURE ACROSS THE CWA AS SHOWERS WILL PUSH BACK IN
FROM THE WEST SOON AFTER SUNRISE INTO THE MID MORNING HOURS.
MOUNTAIN SNOW AND VALLEY RAIN EXPECTED AS THE SNOW LEVEL SHOULD
REMAIN ABOVE THE 7000 FOOT MARK. SNOW AMOUNTS HAVE INCREASED
SLIGHTLY BASED ON THE LATEST MODEL RUNS, AND AS SUCH, HAVE
ISSUED WINTER WEATHER ADVISORIES FOR THE WESTERN MOUNTAINS WITH
THE MAIN IMPACTS BEING TRAVEL OVER THE PASSES. 4 TO 8 INCHES IS
THE HIGHEST PROBABILITY OF SNOWFALL (50-70%) FOR THESE AREAS
WITH THE HIGHER AMOUNTS CONFINED TO THE HIGHEST TERRAIN UP TO A
FOOT POSSIBLE (40-50%).
HEADING INTO MONDAY AFTERNOON, THESE SHOWERS WILL PUSH EAST OF
THE DIVIDE WITH MOUNTAIN SNOW ACROSS THE HIGHER TERRAIN AND
LOWER VALLEY RAIN EXPECTED. LIMITED QPF AMOUNTS EXPECTED,
THOUGH, WITH ONLY A COUPLE INCHES OF SNOW FOR THE HIGHER TERRAIN
AND LESS THAN A TENTH OF LIQUID PRECIPITATION FOR LOWER
VALLEYS. THE MOST INTERESTING PART OF THE MID TO LATE AFTERNOON
HOURS, WILL BE THE POSSIBILITY OF LOCALIZED STORM ACTIVITY
ACROSS SOUTHERN PORTIONS OF THE CWA FOR SWEETWATER COUNTY ALONG
THE I-80 CORRIDOR. SOME CAPE VALUES UP TO 100-200 J/KG,
INDICATIVE OF THIS OCCURRENCE, ALBEIT LOW. REGARDLESS, IMPACTS
WILL BE LIMITED OUTSIDE OF A BRIEF DOWNPOUR.
SHOWERS LINGER INTO TUESDAY, BUT OF LESS INTENSITY AS THE TROUGH
AXIS DIPS SOUTH OF THE CWA WRAPPING IN THE EASTERLY FLOW FOR
AREAS EAST OF THE DIVIDE LATE IN THE DAY. POSSIBLE VERY LIGHT
SNOW AT THAT POINT FOR THE LOWER TERRAIN WITH MINIMAL
ACCUMULATIONS POSSIBLE THROUGH THE OVERNIGHT HOURS. THIS WILL
KEEP THE COOLER BUT SEASONABLE TEMPERATURES THROUGHOUT THE WEEK
WITH THE MAIN FINGER OF THE PFJ WELL SOUTHWARD ACROSS THE DESERT
SOUTHWEST. VERY ISOLATED SHOWERS POSSIBLE LINGER THURSDAY AND
FRIDAY AS WELL BUT LIMITED IN NATURE AS UPPER LEVEL RIDGING
STARTS TO BUILD IN FROM THE WEST. SLIGHTLY WARMER SATURDAY WITH
THE MAIN WARMING TREND SUNDAY AND INTO EARLY NEXT WEEK AS THE
AFOREMENTIONED RIDGE SETS MORE IN PLACE FOR THE UPPER ROCKIES.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 401 PM MDT MON MAR 31 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A SPRING STORM SYSTEM WILL CONTINUE TO IMPACT TERMINALS. SNOW AND
RAIN SHOWERS WILL BRING OCCASIONAL MVFR TO IFR CONDITIONS THROUGH
THE EVENING AS THE NEXT ROUND APPROACHES WYOMING. THERE MAY EVEN BE
SOME RUMBLES OF THUNDER. KBPI, KPNA, AND KRKS SHOULD SEE IMPROVEMENT
TO PREVAILING VFR CONDITIONS AFTER 07-08Z. KJAC IS FAVORED TO SEE
ANOTHER ROUND EARLY TUESDAY MORNING, THOUGH CONFIDENCE HAS DECREASED
WITH THIS FEATURE AND HAVE CHANGED THE PREVAILING GROUP TO A PROB30.
CONDITIONS CLEAR AT ALL TERMINALS BY LATE MONDAY MORNING. WHILE
THERE WILL BE CONTINUED SCATTERED SHOWERS, VFR CONDITIONS ARE
EXPECTED TO PREVAIL AT TERMINALS THROUGH TUESDAY AFTERNOON.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
SCATTERED RAIN AND SNOW SHOWERS WILL CONTINUE TO IMPACT TERMINALS
TODAY, BRINGING OCCASIONAL MVFR TO IFR CONDITIONS. THE BEST CHANCE
FOR THESE IMPACTS WILL BE THROUGH LATE THIS AFTERNOON, THOUGH
ANOTHER ROUND IS EXPECTED TO MOVE IN THIS EVENING. OTHERWISE, GUSTY
WEST TO SOUTHWEST WINDS WILL BE NOTED AT KCOD AND KCPR THROUGH THIS
AFTERNOON. CONDITIONS WILL START TO CLEAR OVERNIGHT, WITH ALL
TERMINALS VFR BY TUESDAY MORNING. GUSTY WINDS WILL BE SEEN AT
MOST TERMINALS THROUGH TUESDAY AFTERNOON. THERE WILL BE ANOTHER
ROUND OF AFTERNOON SHOWERS TUESDAY, THOUGH CONFIDENCE IS LOW ON
THIS FOR NOW.
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
WINTER WEATHER ADVISORY UNTIL 6 PM MDT TUESDAY FOR WYZ001-012-
014-024.
UPDATE...STRAUB
DISCUSSION...LOWE
AVIATION...MYERS
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