852
FXUS65 KRIW 020224
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
824 PM MDT TUE APR 1 2025
KEY MESSAGES
- SNOW CHANCES (50-80%) OVERNIGHT AND WEDNESDAY REMAIN FOCUSED
PRIMARILY ACROSS THE NORTHERN HALF OF THE STATE. A WINTER
WEATHER ADVISORY IS IN EFFECT FOR NORTHERN JOHNSON COUNTY AND
THE BIGHORN MOUNTAINS, WITH A FOCUS ALONG I-90 FROM BUFFALO
TO THE SHERIDAN COUNTY LINE, LATE TONIGHT THROUGH WEDNESDAY
EVENING.
- PRECIPITATION CHANCES (50-70%) CONTINUE THURSDAY AFTERNOON
THROUGH LATE FRIDAY NIGHT.
- A WARMING TREND CONTINUES TO BE FAVORABLE SATURDAY THROUGH
THE FIRST HALF OF NEXT WEEK WITH MINIMAL PRECIPITATION
CHANCES.
UPDATE
ISSUED AT 151 PM MDT TUE APR 1 2025
AN UPPER-LEVEL LOW, EVIDENT ON SATELLITE WATER VAPOR IMAGERY, HAS
POSITIONED ITSELF OVER THE MONTANA/WYOMING REGION. THIS LOW, ALONG
WITH IT'S SURFACE AND 700-MB REFLECTION, WILL DEEPEN AS IT MOVES
INTO EASTERN WYOMING AND THE NORTHERN GREAT PLAINS TONIGHT THROUGH
WEDNESDAY. AS THE LOW MOVES EAST, AN ASSOCIATED FRONT WILL SLOWLY
DIP INTO THE STATE AND PROVIDE FOCUS FOR SNOW OR A RAIN/SNOW MIX
TONIGHT THROUGH LATE WEDNESDAY NIGHT.
AN AREA FOR CONCERN WITH SOUTHERLY FLOW ALOFT AND NORTHERLY LOW-
LEVEL FLOW CONTINUES TO BE THE BIGHORN MOUNTAINS AS WELL AS
NORTHERN JOHNSON COUNTY. SNOW WILL BE MAXIMIZED IN THIS AREA
WITH THE SOUTHERLY FLOW USHERING IN SUBSTANTIAL MOISTURE (80%
CHANCE OF AT LEAST 0.2 INCH OF LIQUID) LATE TONIGHT THROUGH
WEDNESDAY EVENING. COLD 700-MB TEMPERATURES AROUND -10C AND
SURFACE TEMPERATURES NEAR FREEZING WILL SUPPORT ALL SNOW FALLING
ACROSS NORTHERN JOHNSON COUNTY. PRECIPITATION RATES WILL BE
ENHANCED WITH THE FRONTAL BOUNDARY AND MAXIMIZED UPPER-LEVEL
DIVERGENCE. BECAUSE OF THESE FAVORABLE DYNAMICS, A WINTER
WEATHER ADVISORY HAS BEEN ISSUED FOR NORTHERN JOHNSON COUNTY FOR
SNOW AMOUNTS BETWEEN 3-4 INCHES, ESPECIALLY ALONG I-90 FROM
BUFFALO TO THE SHERIDAN COUNTY LINE.
OUTSIDE OF THE BIGHORNS AND NORTHERN JOHNSON COUNTY, SNOW OR
RAIN/SNOW CHANCES TONIGHT THROUGH WEDNESDAY NIGHT WILL BE FOCUSED
ALONG THE FRONT. HOWEVER, MOISTURE WILL BE MORE LIMITED (90% +
CHANCE OF LESS THAN 0.2 INCH LIQUID). HIGHER ELEVATIONS COULD SEE UP
TO 5 INCHES OF SNOW AND LOWER ELEVATIONS UP TO AN INCH ON GRASSY
SURFACES. THEREFORE, NO OTHER HEADLINES HAVE BEEN ISSUES. THE FRONT
WILL STALL LATE WEDNESDAY NIGHT ROUGHLY ALONG THE DIVIDE AND SPARE
SOUTHERN WYOMING OF ANY PRECIPITATION. ALL PRECIPITATION
CHANCES DIMINISH LATE WEDNESDAY NIGHT/EARLY THURSDAY MORNING.
DISCUSSION
ISSUED AT 1242 AM MDT TUE APR 1 2025
RAIN/SNOW SHOWERS LINGER ACROSS SOUTHERN PORTIONS OF THE CWA FOR
SOUTHERN NATRONA TO EASTERN SWEETWATER. ACCUMULATIONS LIMITED IN
THAT NECK OF THE WOODS WITH ONGOING SNOWFALL FOR THE WESTERN
MOUNTAINS. THE HIGHEST ACCUMULATIONS HAS ENDED BUT ONGOING
ISOLATED SHOWERS THROUGHOUT THE DAY COMING TO END BY EVENING
TIME. LEESIDE TROUGHING OFF THE NORTHERN BIGHORNS WILL BRING
SOME WRAP AROUND MOISTURE THAT WILL GIVE DECENT SNOWFALL AMOUNTS
ACROSS THE HIGHER TERRAIN AND MOUNTAIN PASSES. 6 TO 12 INCHES
WILL BE THE MOST LIKELY AMOUNTS (70-80%) TO AFFECT GRANITE AND
POWDER RIVER BASIN. HIGHEST SNOWFALL RATES DURING TUESDAY
AFTERNOON AND AGAIN WEDNESDAY, HIGHLIGHTING WINTER WEATHER
ADVISORIES TO BE IN AFFECT ACROSS THOSE TIMEFRAMES WITH THE
STRONGEST INSTABILITIES AND PVA ANOMALIES. THIS WILL PUSH EAST
BY SUNSET WEDNESDAY WITH ONLY VERY LIGHT LINGERING SHOWERS FOR
THIS AREA AND OTHERS EAST OF THE DIVIDE HEADING INTO THE
OVERNIGHT HOURS. OTHERWISE, BREEZY NORTHWEST TO NORTHERLY WINDS
THROUGHOUT THE DAY TUESDAY SEEING GUSTS UP TO 30 TO 40 MPH FOR
THE WIND PRONE AREAS AND LOCALLY HIGHER IN THE MOUNTAIN PASS
AREAS OF SNOW.
AS WE PROGRESS INTO THURSDAY, THE MAIN TROUGH EXTENDS FURTHER
SOUTH PULLING THE ENERGY WITH THE MAIN FINER OF THE PFJ WELL TO
THE SOUTH EXITING INTO THE HIGH PLAINS AND MID-WEST. SOME
INSTABILITY REMAINS WITH THE DIVERGENCE ALOFT THROUGH FRIDAY AND
SATURDAY MORNING WITH SPORADIC RAIN/SNOW SHOWERS, DEPENDENT ON
ELEVATION. LESS ACTIVITY REGARDLESS AS UPPER LEVEL RIDGING
BUILDS IN FROM THE WEST WITH EVER INCREASING CONVERGENCE ALOFT.
STRONG MODEL CONVEYANCE OF HIGH AMPLITUDE RIDGING THAT WILL GIVE
WAY TO A DRY AND WARMING TREND STARTING SUNDAY ONWARD INTO MUCH
OF NEXT WEEK. LONG TERM GUIDANCE INDICATES THE NEXT BEST CHANCE
FOR PRECIPITATION WILL BE LIMITED AND PUSH TOWARDS THE MID TO
END OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 403 PM MDT TUE APR 1 2025
SCATTERED RAIN AND SNOW SHOWERS WILL CONTINUE TO BE THE PRIMARY
AVIATION CONCERN THROUGH THE PERIOD. TIMING REMAINS A FORECAST
CHALLENGE, AND TAFS REFLECT LOWER CONFIDENCE ON THIS WITH LESS
PREVAILING IMPACTS AND MORE TEMPO/PROB30 GROUPS. STILL, MVFR TO IFR
IMPACTS ARE EXPECTED AT TIMES FOR MOST TERMINALS THROUGH THIS
EVENING, WITH CHANCES GENERALLY DECREASING OVERNIGHT. ONE THING TO
NOTE WILL BE A COLD FRONT SURGE AROUND SUNRISE WEDNESDAY, BRINGING
MVFR CEILINGS TO KCOD, KWRL, AND KCPR. KCOD IS ALSO FAVORED TO SEE
SNOW DURING THIS TIME. CONVECTION COVERAGE WILL INCREASE AGAIN BY
LATE WEDNESDAY MORNING, WITH SCATTERED SHOWERS PERSISTING ACROSS
MUCH OF THE AREA THROUGH 00Z THURSDAY.
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 WEDNESDAY FOR WYZ008-
009.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT WEDNESDAY FOR WYZ010.
UPDATE...GERHARDT
DISCUSSION...LOWE
AVIATION...MYERS
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