553
FXUS65 KRIW 291949
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
149 PM MDT SAT MAR 29 2025
KEY MESSAGES
- RAIN CHANCES (40-50%) EXIST ACROSS MUCH OF THE AREA THIS
AFTERNOON WITH POTENTIAL FOR A FEW RUMBLES OF THUNDER IN
SOUTHERN WYOMING.
- WIDESPREAD PRECIPITATION REMAINS LIKELY (80-90%+) THIS
EVENING AND OVERNIGHT WITH RAIN TRANSITIONING TO A RAIN/SNOW
MIX AND THEN ALL SNOW. ALL SNOW IS EXPECTED IN THE MOUNTAINS.
- A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE EASTERN
SLOPES OF THE WIND RIVER AND BIGHORN MOUNTAINS AND THE
ABSAROKAS, STARTING 4PM THIS AFTERNOON FOR SNOW AMOUNTS
BETWEEN 6-12 INCHES.
- THIS WET AND SEASONABLE PATTERN REMAINS IN PLACE THROUGH MUCH
OF THE UPCOMING WEEK.
UPDATE
ISSUED AT 144 PM MDT SAT MAR 29 2025
19Z SATELLITE IMAGERY SHOWS DIURNAL CUMULUS SCATTERED ACROSS THE
AREA AS LOW-LEVEL MOISTURE INCREASES AHEAD OF THE NEXT WEATHER
SYSTEM. THE UPPER-LOW'S TROUGH AXIS REMAINS ON TRACK TO TRAVERSE THE
STATE OVERNIGHT. AHEAD OF THE TROUGH AXIS IS AN ASSOCIATED REGION OF
PVA AND VORTICITY MAXIMUMS WHICH WILL PROVIDE SUPPORT ALOFT FOR
SCATTERED RAIN SHOWERS THIS AFTERNOON AND EVENING. A FEW RUMBLES OF
THUNDER CANNOT BE RULED OUT ACROSS SOUTHERN WYOMING THIS
AFTERNOON WITH SBCAPE VALUES RANGING FROM 250-500 J/KG.
AS THE TROUGH AXIS MAKES ITS WAY ACROSS THE REGION, IT'S 700-MB
REFLECTION WILL TREK FROM SOUTHERN WYOMING TOWARDS EAST-CENTRAL
WYOMING. THIS 700-MB LOW TRACK IS A FAVORABLE FLOW PATTERN FOR
SUFFICIENT MOISTURE TRANSPORT INTO CENTRAL AND NORTHERN
WYOMING. HOWEVER, THERE REMAINS UNCERTAINTY IN THE EXACT PATH OF
THIS 700-MB LOW, HOW LOW SNOW LEVELS GET, AND THE PRECIPITATION
RATES (WHICH WILL OVERALL IMPACT SNOW TOTALS). SHOULD THE LOW
TREK IN A "LINE" FROM NORTHERN SWEETWATER COUNTY ACROSS
SOUTHEAST FREMONT COUNTY AND INTO NATRONA COUNTY, THE LOWER
ELEVATIONS OF THE WIND RIVER BASIN COULD SEE A FEW INCHES OF WET
SNOW OVERNIGHT. IF THE 700-MB LOW TRACKS FARTHER EAST, TOTAL
SNOW AMOUNTS WOULD BE LESS AND THIS IS WHAT THE CURRENT FORECAST
REFLECTS. ADDITIONALLY, SHOULD PRECIPITATION RATES BE HIGHER,
PRECIPITATION WILL BE ABLE TO OVERCOME THE SLIGHTLY ABOVE
FREEZING SLIGHTLY TEMPERATURES AND LOWER THE SNOW LEVEL. THIS
WILL RESULT IN PRECIPITATION FALLING FOR LESS TIME AS A
RAIN/SNOW MIX AND LONGER AS SNOW.
ALL THIS BEING SAID, THE WINTER WEATHER ADVISORIES GO INTO EFFECT AT
4PM THIS AFTERNOON WITH SNOW AMOUNTS GREATER THAN 6 INCHES STILL
LIKELY (90%+) ACROSS THE EASTERN SLOPES OF THE WIND RIVER
MOUNTAINS AND THE SOUTHERN PORTIONS OF THE ABSAROKAS.
SIMILARLY, THE FLOW PATTERN REMAINS FAVORABLE FOR 6+ INCHES OF
SNOW ACROSS THE EASTERN SLOPES OF THE BIGHORN MOUNTAINS.
DISCUSSION
ISSUED AT 126 AM MDT SAT MAR 29 2025
SHOWERS HAVE PUSHED INTO NATRONA COUNTY EARLY THIS MORNING AS
EXPECTED, WITH A SFC REFLECTION OF THE MID LEVEL LOW EVIDENT ON
RADAR OVER WESTERN PORTIONS OF THE COUNTY. ADDITIONAL SHOWERS
OVER THE BIGHORN BASIN WILL ALSO CONTINUE THROUGH THE REST OF
THE MORNING. PRECIPITATION AMOUNTS OF 0.3" TO 0.5" OVER
JOHNSON/NATRONA COUNTIES THROUGH 18Z ARE STILL EXPECTED. SNOW
LEVELS LOOK TO DROP AS LOW AS 6500FT THIS MORNING, WHICH WILL
LEAD TO A FEW INCHES OF SNOW OVER THE BIGHORNS FROM THIS EVENT.
RAIN SHOWERS/MOUNTAIN SNOW WILL CONTINUE OVER JOHNSON COUNTY/THE
BIGHORNS THROUGH THE REST OF THE MORNING AND GRADUALLY END THIS
AFTERNOON. AT THE SAME TIME, ISOLATED SHOWERS WILL BECOME POSSIBLE
OVER THE WESTERN MOUNTAINS, WITH INCREASING CHANCES (20-40%) OVER
THE I-80 CORRIDOR LATE IN THE AFTERNOON. SHOWERS OF THE WIND RIVER
AND ABSAROKA MOUNTAINS WILL BEGIN TO SPREAD INTO THE WIND RIVER
BASIN THIS EVENING AFTER 00Z. RAIN SHOWERS/MOUNTAIN SNOW WILL BECOME
MORE WIDESPREAD OVER CENTRAL AND WESTERN PORTIONS THROUGH 06Z AS THE
REMNANTS OF AN UPPER LOW MOVE OVER THE CWA. PRECIPITATION WILL
CONTINUE THROUGH TONIGHT WITH RAIN CHANGING OVER TO SNOW FOR MOST
AREAS BETWEEN 06Z AND 09Z SUNDAY. THE MAIN LOW WILL TAKE A SIMILAR
TRACK AS THE MIDLEVEL CURRENTLY, MOVING ACROSS SWEETWATER COUNTY
TOWARD SOUTHERN NATRONA COUNTY BETWEEN 00Z AND 06Z SUNDAY. ANY SNOW
ACCUMULATION IN THE LOWER ELEVATIONS WILL OCCUR OVERNIGHT, WITH THE
BETTER ACCUMULATIONS STAYING IN GRASSY AREAS. CONFIDENCE FOR HIGHER
SNOWFALL TOTALS (6 TO 12 INCHES) ARE ALONG THE EAST SLOPES OF THE
BIGHORN AND WIND RIVER MOUNTAINS AND THE SOUTHERN END OF THE
ABSAROKAS. OTHERWISE, SNOWFALL AMOUNTS IN THE MOUNTAINS WILL RANGE
BETWEEN 3 TO 6 INCHES.
PRECIPITATION WILL END ACROSS MOST AREAS WEST OF THE DIVIDE, FROM
JACKSON TO WAMSUTTER, BETWEEN 12Z AND 15Z, AS THE MAIN TROUGH AXIS
EXITS EASTWARD OVER THE PLAINS. SNOW WILL CONTINUE ACROSS AREAS EAST
OF THE DIVIDE SUNDAY MORNING, ESPECIALLY ALONG AND EAST OF A LOVELL-
TO-CASPER LINE, WITH ANY SNOW REMAINING CONFINED TO GRASSY AREAS. AS
THIS MAIN AREA OF PRECIPITATION EXITS TO THE EAST, ADDITIONAL
ISOLATED SHOWERS WILL REDEVELOP ACROSS THE FORECAST AREA THROUGH THE
AFTERNOON.
A RIDGE WILL BUILD OVER THE REGION IRT ANOTHER STRONG UPPER LOW
MAKES ITS WAY TO THE PACNW. THIS WILL KEEP PACIFIC MOISTURE
STREAMING OVER THE REGION AND COULD RESULT IN RAIN SHOWERS AND
ISOLATED THUNDERSTORMS OVER WESTERN AND SOUTHERN PORTIONS AND SNOW
IN THE WESTERN MOUNTAINS. SOME OF THIS ACTIVITY COULD SPREAD EAST OF
THE DIVIDE MONDAY EVENING. TEMPERATURES WILL ALSO REMAIN NEAR
NORMAL. SIMILAR ACTIVITY WILL RETURN TUESDAY AND INCLUDE NORTHERN
PORTIONS OF THE FORECAST AREA, AS A TROUGH FROM THE UPPER LOW MOVES
OVER THE COWBOY STATE. THE REMNANTS OF THE MAIN UPPER LOW COULD
REACH THE AREA BY LATE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT,
KEEPING CHANCES FOR PRECIPITATION CONTINUING.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1132 AM MDT SAT MAR 29 2025
LOW CLOUDS WILL CONTINUE TO RISE AND SCATTER TO VFR THIS AFTERNOON,
EXCEPT AT KCPR. A WEATHER SYSTEM WILL PASS THROUGH THE AREA THIS
EVENING THROUGH SUNDAY. WIDESPREAD IMPACTS WILL OCCUR FROM THIS
WEATHER SYSTEM AS RAIN AND SNOW DEVELOPS. MOST TERMINALS WILL HAVE
PREVAILING VFR CONDITIONS THROUGH THIS AFTERNOON, WITH IFR AT KCPR
DUE TO LOW CIGS.
PRECIPITATION IS SET TO BEGIN THIS EVENING/TONIGHT AT ALL TERMINALS
AS AN AREA OF RAIN/SNOW MOVES NORTHEAST ACROSS WESTERN AND CENTRAL
WYOMING. SOME CONVECTIVE SHOWERS WILL DEVELOP THIS AFTERNOON PRIOR
TO THIS AREA OF RAIN/SNOW AND WOULD MAINLY IMPACT KRKS/KLND. SOME
ISOLATED LIGHTNING IS POSSIBLE (15%) THROUGH EARLY EVENING WITH THE
CONVECTIVE SHOWERS. INITIALLY, PRECIPITATION WILL BE IN THE FORM OF
RAIN, BUT SHOULD QUICKLY CHANGE OVER TO SNOW OVERNIGHT. CIGS WILL
DROP TO MVFR/IFR FOR MOST TERMINALS TONIGHT, WITH LIFR AT KLND AND
POSSIBLY (30%) AT KRIW. PRECIPITATION WILL END FROM WEST TO EAST
SUNDAY MORNING, BUT MORE CONVECTIVE SHOWERS ARE POSSIBLE (30%)
SUNDAY AFTERNOON. FREQUENT MOUNTAIN OBSCURATION FROM THIS EVENING
THROUGH SUNDAY MORNING.
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 NOON MDT SUNDAY FOR WYZ002-015.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT SUNDAY FOR WYZ009.
UPDATE...GERHARDT
DISCUSSION...LAVOIE
AVIATION...ROWE
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