315
FXUS65 KRIW 180914
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
214 AM MST MON NOV 18 2024
KEY MESSAGES
- SNOW TODAY, MAINLY ACROSS THE WESTERN WYOMING MOUNTAINS. SNOW SHOWERS
MAY BRING BRIEF SNOW TO LOWER ELEVATIONS.
- WINDY TODAY, WITH GUSTS 20 TO 40 MPH.
- COLD AND BREEZY TUESDAY. LIGHT SNOW CONTINUES ACROSS WESTERN MOUNTAINS.
- WARMER TEMPERATURES FOR THE LATTER HALF OF THE WEEK.
DISCUSSION
ISSUED AT 213 AM MST MON NOV 18 2024
A TROUGH MOVES THROUGH THE AREA TODAY, RESULTING IN WIND AND SNOW.
STARTING WITH WIND, IT WILL BE WINDY TODAY FOR MOST OF THE AREA,
BOTH HIGHER AND LOWER ELEVATIONS. GUSTY WINDS BECOME MORE WIDESPREAD
FOR THE LOWER ELEVATIONS STARTING LATE MORNING. GUSTS 20 TO 35 MPH
WILL BE COMMON. FOR SWEETWATER COUNTY, NORTHEAST THROUGH SOUTHEAST
FREMONT COUNTY, AND THROUGH NATRONA COUNTY, GUSTS UP TO AROUND 45
MPH ARE POSSIBLE LATE INTO THIS EVENING. WINDS DECREASE A LITTLE
OVERNIGHT, BUT IT REMAINS BREEZY FOR MUCH OF THE AREA.
SNOW IS OTHER WEATHER ELEMENT OF TODAY. SNOW AMOUNTS LOOK FAIRLY
SIMILAR TO PREVIOUS FORECAST SHIFTS. AS A RESULT, WILL KEEP WINTER
HIGHLIGHTS AS ARE, WITH A WINTER STORM WARNING FOR THE TETONS, AND A
WINTER WEATHER ADVISORY FOR YELLOWSTONE/SALT RIVER AND WYOMING
RANGES. SNOWFALL TOTALS FOR THE TETONS INTO THE PLATEAUS OF
SOUTHWEST YELLOWSTONE ARE STILL ON TRACK FOR 10 TO 15 INCHES, WITH
LOCALLY HIGHER AMOUNTS AT THE HIGHEST ELEVATIONS. THE HEAVIEST SNOW
OVER THESE WESTERN MOUNTAINS OCCURS THROUGH MID-AFTERNOON TODAY.
THE BIGHORN TOTALS HAVE COME UP A BIT. ACROSS THE NORTHERN RANGE,
TOTALS ARE ON THE EDGE OF ADVISORY AMOUNTS (5 TO 8 INCHES). HOWEVER,
GIVEN WINDY CONDITIONS OVER THE PASSES, AS WELL AS MODELS INDICATING
AMOUNTS UP TO 10 INCHES ACROSS THE SOUTHERN RANGE, HAVE ADDED AN
ADVISORY TO THE WESTERN BIGHORN MOUNTAINS FOR TODAY. THE HEAVIEST
SNOW LOOKS TO FALL BETWEEN MID-AFTERNOON AND LATE EVENING, BEFORE
LESSENING BY AROUND MIDNIGHT.
FOR THE LOWER ELEVATIONS, SNOW SHOWERS MOVING THROUGH TODAY MAY
BRING SOME BRIEF SNOW. HOWEVER, TOTAL SNOW AMOUNTS ARE STILL UNDER
AN INCH MOST EVERYWHERE, WITH A MAJORITY BETWEEN 0 AND 0.5 INCHES OF
SNOW. MODELS ARE HINTING AT SOME STRONGER SNOW SHOWERS OVER NATRONA
COUNTY INTO SOUTHERN JOHNSON COUNTY LATE THIS EVENING. THIS COULD
BRING AMOUNTS UP TO 2 INCHES.
SNOW MAINLY COMES TO AN END BY MIDNIGHT, BUT LINGERS OVER THE
WESTERN MOUNTAINS THROUGH TUESDAY. THIS SNOW WILL BE ON THE LIGHTER
SIDE, ESPECIALLY STARTING TUESDAY MORNING. UP TO 4 MORE INCHES OF
SNOW IS POSSIBLE FOR THE TETONS MONDAY NIGHT THROUGH TUESDAY, WITH
LESS ELSEWHERE.
POST COLD FRONT, TEMPERATURES TUESDAY ARE NOTABLY COOLER, ESPECIALLY
SINCE THE GUSTY WINDS CONTINUE. CLOUDS CLEARING OUT FOR THE NIGHT
WILL RESULT IN COLD LOWS WEDNESDAY MORNING, WITH NEGATIVE SINGLE
DIGITS WEST OF THE CONTINENTAL DIVIDE, AND VALUES GENERALLY RANGING
FROM 10 TO 15 DEGREES EAST OF THE DIVIDE. OUTSIDE MOUNTAIN SNOW
SHOWERS, LOWER ELEVATIONS ARE DRY.
BRIEF RIDGING TAKES PLACE, THEN, THROUGH THE END OF THE WEEK.
TEMPERATURES REBOUND QUICKLY, WITH HIGHS IN THE 40S AND 50S THURSDAY
THROUGH SATURDAY. DURING THIS TIME, AN ACTIVE PATTERN OVER THE
PACIFIC NORTHWEST KEEPS MOISTURE FILTERING INTO THE WESTERN
MOUNTAINS, SO SNOW CHANCES (15% TO 70%) REMAIN FOR THE WEST, THOUGH
OVERALL SNOW AMOUNTS ARE RELATIVELY LIGHT DURING THIS TIME. THERE IS
POTENTIAL FOR SOME SHORTWAVE ENERGY TO GET DISPLACED TO WYOMING THIS
WEEKEND, WHICH WOULD RESULT IN HEAVIER SNOW. CONFIDENCE IS LOW AT
THIS RANGE, THOUGH IMPACTS MAINLY LOOK TO REMAIN TO THE WESTERN
MOUNTAINS.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 930 PM MST SUN NOV 17 2024
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS
CHANCES FOR SNOW CONTINUE TO INCREASE OVER THE FAR WESTERN
MOUNTAINS BY THE START OF THE TAF PERIOD. MARGINAL VFR
CONDITIONS EXPECTED AT KJAC TO START, WITH SNOW DEVELOPING
AROUND 07Z/08Z. MVFR CONDITIONS WILL DROP TO IFR AS THE SNOW
BECOMES STEADY. THIS ENHANCED BAND OF SNOW WILL PUSH SOUTHEAST
BETWEEN 08Z-12Z TO REACH KBPI/KPNA AND ON TO KRKS BETWEEN
13Z-16Z. THE BEST CHANCE FOR IFR CONDITIONS WILL BE AT KJAC
WITH THIS BAND, BUT KPNA AND POTENTIALLY KRKS COULD EACH SEE A
ONE- TO TWO-HOUR PERIOD OF IFR. TEMPO GROUP HAS BEEN ADDED AT
KPNA FOR THIS ENHANCED BAND. OROGRAPHIC MVFR SNOW CONTINUES
THROUGH AT LEAST MIDDAY AT KJAC, WHILE OTHER WESTERN TERMINALS
SEE CONDITIONS GRADUALLY RETURN TO VFR BY EARLY AFTERNOON. GUSTY
SOUTHWEST SURFACE WIND BEGINS LATE MONDAY MORNING AT KJAC,
WHILE OTHER TERMINALS FIND WESTERLY WIND INCREASE TO 20-30 KT
EARLY MONDAY AFTERNOON BEHIND PASSAGE OF THE SHORTWAVE. MOUNTAIN
TOPS WILL BE OBSCURED THROUGH THE FORECAST PERIOD.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS
TERMINALS TO REMAIN VFR THROUGH MIDDAY MONDAY AHEAD OF AN
APPROACHING SHORTWAVE TROUGH. WIND GUSTS AROUND 20 KT WILL
CONTINUE AT KCOD BEFORE DECREASING BY 11Z. A FAVORABLE PRESSURE
GRADIENT ALLOWS FOR GUSTY WIND (30-35 KT) TO CONTINUE OVERNIGHT
AT KCPR ALONG WITH A LAYER OF WIND SHEAR IN THE LOWEST 1,500 FT
AGL. A COLD FRONT PUSHES SOUTHWARD THROUGH KCOD AND KWRL
BETWEEN 16Z- 20Z WITH NORTHERLY/NORTHWESTERLY WIND AND
SCATTERED SNOW SHOWERS DEVELOPING DURING THAT TIME. KCOD AND
KWRL EACH HAVE A 40-60 PERCENT CHANCE OF MVFR CONDITIONS AFTER
21Z, AND HAVE TRENDED TOWARD PREVAILING LOW-END VFR OR PROB30
IN LIGHT SNOW AT BOTH TERMINALS. AHEAD OF THE FRONT, GUSTY
WESTERLY WIND CONTINUES AT KCPR, EVENTUALLY DEVELOPING AT KRIW
AND KLND AROUND 20Z BEHIND THE PASSAGE OF THE SHORTWAVE.
INSTABILITY FAVORS WIDELY SCATTERED LATE DAY SNOW SHOWERS OVER
CENTRAL WYOMING, BUT IMPACTS AT SPECIFIC TERMINALS WOULD BE
SHORT-LIVED. WINDS WILL GRADUALLY DECREASE BEHIND THE FRONT,
FIRST AT KCOD AFTER 00Z, THEN KWRL, KRIW AND KLND BETWEEN 03Z
AND 06Z/TUESDAY. THE COLD FRONT MAY REACH KCPR BY THE END OF THE
TAF PERIOD, TURNING WINDS MORE NORTH-NORTHWEST. THERE WILL BE A
CHANCE FOR THE AFOREMENTIONED SNOW SHOWERS TO IMPACT THE
TERMINAL WITH MVFR CONDITIONS AS WELL. MOUNTAIN TOPS WILL BE
INCREASING OBSCURED AFTER 12Z.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON SMOKE, ICING, AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 10 PM MST THIS EVENING FOR
WYZ001-024.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 10 PM MST
THIS EVENING FOR WYZ008.
WINTER STORM WARNING UNTIL 10 PM MST THIS EVENING FOR WYZ012.
DISCUSSION...WITTMANN
AVIATION...LAVOIE
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