157
FXUS65 KRIW 312119
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
319 PM MDT MON MAR 31 2025
KEY MESSAGES
- ISOLATED BANDS OF MODERATE TO HEAVY SNOW AND THUNDER ARE
POSSIBLE THROUGH SUNSET WITH ACCUMULATIONS LARGELY LESS THAN
AN INCH. GUSTY WINDS AND REDUCED VISIBILITIES WILL ACCOMPANY
THESE BANDS.
- 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.
- CHANCES FOR SNOW OR A RAIN/SNOW MIX REMAIN POSSIBLE THROUGH
THE FIRST HALF OF THE WEEKEND.
UPDATE
ISSUED AT 312 PM MDT MON MAR 31 2025
THE 21Z MESOANALYSIS PAGE SHOWS AN AREA OF SBCAPE BETWEEN 250-500
J/KG COINCIDING WITH MID-LEVEL LAPSE RATES AROUND 8 C/KM ACROSS
THE SOUTHERN HALF OF WYOMING. THIS INSTABILITY COMBINED WITH
SUFFICIENT MOISTURE AND PVA ALOFT HAS ALLOWED FOR ISOLATED
BANDS OF MODERATE TO HEAVY SNOW TO DEVELOP ACROSS PORTIONS OF
THE AREA. TEMPERATURES TODAY HAVE STRUGGLED TO RISE ABOVE 35-40
DEGREES F WITH THE ABUNDANT CLOUD COVER; THEREFORE, ANY
PRECIPITATION WILL FALL AS A WET SNOW IN THESE MODERATE TO
HEAVY BANDS. EXPECT GUSTY WINDS AND REDUCED VISIBILITIES IN
THESE BANDS. THE DEVELOPMENT/CONTINUING OF THESE BANDS COULD
OCCUR UNTIL SUNSET, WHEN INSTABILITY DIMINISHES. ACROSS WESTERN
WYOMING, MODERATE TO HEAVY SNOW IS EXPECTED BETWEEN 5PM-11PM
ACROSS THE WESTERN MOUNTAINS, WHERE A WINTER WEATHER ADVISORY
REMAINS IN EFFECT.
AN UPPER-LOW OFF THE PACIFIC NORTHWEST COAST WILL TREK EAST TOWARDS
THE NORTHERN INTERMOUNTAIN WEST TUESDAY MORNING AND KEEP
CONTINUOUS MOISTURE FLOW INTO THE REGION. THIS UPPER-LOW'S
700MB REFLECTION WILL TRACK FROM MONTANA TO THE CENTRAL GREAT
PLAINS DURING THE DAY TUESDAY. THIS NORTHWEST FLOW COULD CREATE
GUSTY NORTHWEST DRAINAGE WINDS IN THE WIND RIVER BASIN WHERE
THERE IS AN 80% CHANCE OF SUSTAINED WINDS OF 30 MPH TUESDAY
AFTERNOON. PRECIPITATION CHANCES CONTINUE TUESDAY THROUGH
WEDNESDAY NIGHT AS THE LOW TREKS EAST. THE PRECIPITATION WILL
BE FOCUSED ALONG AN ASSOCIATED WEAK FRONT AS IT DROPS SOUTH
DURING THIS TIMEFRAME. SNOW AMOUNTS TUESDAY THROUGH WEDNESDAY
NIGHT ARE FORECAST TO BE BETWEEN 4-8 INCHES IN HIGHER ELEVATIONS
WITH LOCALLY HIGHER AMOUNTS POSSIBLE. LOWER ELEVATIONS CAN
EXPECT SNOW AMOUNTS UP TO AN INCH.
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 /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1206 PM MDT MON MAR 31 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A SPRING STORM SYSTEM WILL CONTINUE TO IMPACT TERMINALS TODAY. SNOW
AND RAIN SHOWERS WILL BRING FREQUENT MVFR TO IFR CONDITIONS THROUGH
THE EVENING, THOUGH WITH PLENTY OF BREAKS IN THIS ACTIVITY. 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, WITH CONDITIONS
CLEARING AGAIN AFTER 16Z.
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 THIS AFTERNOON, THOUGH ANOTHER
ROUND IS EXPECTED TO MOVE IN LATE THIS EVENING. OTHERWISE, GUSTY
WEST TO SOUTHWEST WINDS WILL BE NOTED AT KCOD AND KCPR THIS
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
WINTER WEATHER ADVISORY UNTIL 6 PM MDT TUESDAY FOR WYZ001-012-
014-024.
UPDATE...ROWE
DISCUSSION...LOWE
AVIATION...MYERS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page