378
FXUS65 KCYS 171158
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
458 AM MST TUE DEC 17 2024
KEY MESSAGES
- A WINTER STORM WARNING IS IN EFFECT UNTIL 8 PM TONIGHT FOR THE SNOWY
RANGE, WITH A WINTER WEATHER ADVISORY UNTIL 8 PM TONIGHT FOR
THE SIERRA MADRE RANGE. A HIGH WIND WARNING WILL CONTINUE
UNTIL 11 AM TODAY FOR WIND PRONE LOCATIONS OF SOUTHEAST
WYOMING.
- ANOTHER HIGH WIND EVENT IS LOOKING LIKELY FOR LATE TUESDAY
NIGHT THROUGH LATE WEDNESDAY NIGHT FOR ARLINGTON, BORDEAUX,
THE I-80 SUMMIT AND FOOTHILLS AND FOR NORTHERN CARBON COUNTY.
- RELATIVELY MILD AND DRY WEATHER WILL CONTINUE FOR THURSDAY
THROUGH THE WEEKEND.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED AT 123 AM MST TUE DEC 17 2024
TODAY...AN INCOMING SHORTWAVE TROUGH AND OROGRAPHIC SNOWS LOOK ON
TRACK PER THE MODELS, AND WITH QPF LOOKING A BIT HIGHER FROM WPC AND
THE MODELS, WE EXPECT SOME HIGHER SNOWFALL AMOUNTS FOR THE SNOWY
RANGE SO WE HAVE UPGRADED TO A WINTER STORM WARNING THERE FOR 12 TO
15 INCHES TOTAL. LESSER SNOWFALL TOTALS EXPECTED FOR THE SIERRA
MADRE RANGE WITH 5 TO 10 INCHES TOTAL ACCUMULATION.
AS FAR AS WINDS GO, PEAK WINDS SHOULD DECREASE THIS MORNING AS THE
CRAIG TO CASPER 850/700 MB HEIGHT DIFFERENCES DECREASE FROM 54/50
METERS AT 12Z TO 26/36 METERS AT 18Z, THUS THE 11 AM ENDING OF THE
HIGH WIND WARNING LOOKS ON TRACK. OVERALL, IT WILL BE A BREEZY TO
WINDY AFTERNOON WITH NEAR SEASONABLE TEMPERATURES.
TONIGHT...ANOTHER HIGH WIND EVENT LOOKS MORE LIKELY LATE TONIGHT
UNDER STRONG NORTHWEST FLOW ALOFT. CRAIG TO CASPER 850/700 MB HEIGHT
DIFFERENCES INCREASE TO 73/57 METERS BY 12Z WITH OUR LOCAL HIGH WIND
MODEL SUGGESTING WINDS INCREASING AFTER MIDNIGHT, THUS WE HAVE
ISSUED A HIGH WIND WATCH FOR OUR WIND PRONE LOCATIONS STARTING AT 2
AM, INCLUDING ARLINGTON, BORDEAUX, THE I-80 SUMMIT AND FOOTHILLS AND
NORTHERN CARBON COUNTY.
WEDNESDAY...NORTHWEST FLOW ALOFT STRENGTHENS EVEN FURTHER WITH THE
CRAIG-CASPER 850/700 MB HEIGHT DIFFERENCES INCREASING TO 87/67
METERS BY 00Z AND 700 MB WINDS NEAR 50 KNOTS WITH LOCAL HIGH WIND
MODELS SUGGESTING WINDS EXCEEDING HIGH WIND CRITERIA FOR OUR WIND
PRONE LOCATIONS, AND POSSIBLY NEARBY LOCATIONS. THUS WINDS EXPECTED
TO RAMP UP EVEN MORE FOR OUR WIND PRONE LOCATIONS AND THE HIGH WIND
WATCH CONTINUES. TEMPERATURES WILL BE WARMER WITH 700 MB
TEMPERATURES NEAR 2 CELSIUS.
WEDNESDAY NIGHT...LOW AND MID LEVEL GRADIENTS REMAIN STRONG ALTHOUGH
CRAIG TO CASPER 850/700 MB HEIGHT DIFFERENCES SLOWLY DECREASE TO
64/57 METERS BY 12Z, THUS THE HIGH WIND WATCH CONTINUES FOR OUR WIND
PRONE LOCATIONS. NOT AS COLD AS THE PREVIOUS NIGHT DUE TO EXPECTED
WINDS AND A MODERATING AIRMASS.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED AT 123 AM MST TUE DEC 17 2024
DETERMINISTIC/ENSEMBLE MODELS ARE ALL DEPICTING THE UPPER LEVEL
SHORTWAVE MOVING INTO THE NORTHERN PLAINS ON THURSDAY.
FOLLOWING IN ITS TRACKS THE WPC CLUSTERS AND VARIOUS ENSEMBLES
ARE SHOWING AN UPPER LEVEL RIDGE BUILDING OVER THE CENTRAL AND
NORTHERN ROCKIES. THIS WILL CAUSE THE PRESSURE/HEIGHT GRADIENTS
TO SLACKEN DURING THE COURSE OF THE DAY ON THURSDAY. EVEN WITH
THE GRADIENTS WEAKENING WE MAY CONTINUE TO BE QUITE WINDY OVER
THE WIND PRONE AREAS ON THURSDAY MORNING, BUT THIS SHOULD NOT
LAST TOO LONG AS THE UPPER LEVEL RIDGE BUILDS INTO THE AREA.
THE REMAINDER OF THE WEEKEND IS LOOKING QUITE MILD WITH NAEFS
SHOWING TEMPERATURES AROUND ONE STANDARD DEVIATION ABOVE NORMAL
FOR THIS TIME OF YEAR. THIS ALSO AGREES WITH THE WPC CLUSTERS
WITH ALL FOUR CLUSTERS SHOWING THE ANOMALOUS UPPER LEVEL RIDGE
IN PLACE. AT THIS POINT, IT LOOKS LIKE A GOOD WEEKEND TO BE
OUTDOORS ESPECIALLY IN THE LOWER ELEVATIONS EAST OF THE I-25
CORRIDOR WHERE AFTERNOON HIGHS COULD REACH THE MID TO UPPER
50S.
THERE IS LITTLE MORE UNCERTAINTY EARLY NEXT WEEK ON HOW THE
PATTERN WILL EVOLVE. THERE IS A CHANCE THAT THE RIDGE MAY BREAK
DOWN A BIT. WE WILL ALSO NEED TO KEEP AN EYE ON THE TRACK OF A
CLOSED LOW MOVING TOWARDS THE CALIFORNIA COASTLINE EARLY NEXT
WEEK. AT THIS POINT IT IS TOO EARLY TO SAY WHETHER THIS CLOSED
LOW WILL HAVE ANY IMPACTS TO OUR REGION. STAY TUNED!
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 441 AM MST TUE DEC 17 2024
LATEST WEB CAMS WERE SHOWING SCATTERED SNOW SHOWERS DEVELOPING
MAINLY WEST OF KLAR. THESE SNOW SHOWERS ARE REDUCING THE
VISIBILITY TO A 1 MILE OR LESS AT TIMES. THE SCATTERED SNOW
SHOWERS WILL PERSIST ACROSS THIS AREA THROUGH MUCH OF THE
AFTERNOON. SOME OF THESE SNOW SHOWERS MAY DROP THE VISIBILITY TO
LESS THAN ONE HALF MILE AT TIMES ALONG WITH LOWERING CEILINGS
INTO THE MVFR CATEGORY OR EVEN THE IFR CATEGORY IF THEY REALLY
TAP THE GOOD INSTABILITY IN PLACE THIS AFTERNOON. THESE HEAVIER
SNOW SHOWERS COMBINED WITH THE STRONG WINDS MAY EVEN PRODUCE A
FEW SNOW SQUALLS THIS AFTERNOON WITH THEM MOST LIKELY OCCURRING
CLOSER TO THE SNOWY RANGE. ONE CANNOT RULE A POSSIBLE HEAVIER
SNOW SHOWER AROUND KRWL, BUT THE INSTABILITY WILL BE A LITTLE
LESS IN THAT AREA. KLAR WILL MOST LIKELY NOT SEE THESE HEAVIER
SNOW SHOWERS EITHER DUE TO STRONG WEST WINDS YIELDING TO
DOWNSLOPE FLOW IN THIS REGION UNTIL THE AFTERNOON WHEN THE WINDS
MAY TURN A BIT MORE NORTHERLY. THE REST OF THE TAF SITES WILL
SEE MORE GUSTY WINDS TODAY WITH CEILINGS MAINLY ABOVE 10KFT. THE
CLOUD COVER SHOULD BEGIN DISSIPATING WITH THE WIND DIMINISHING
AFTER SUNSET DUE TO THE LOSS OF DIURNAL HEATING.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 11 AM MST THIS MORNING FOR WYZ104-106-
110.
HIGH WIND WATCH FROM LATE TONIGHT THROUGH LATE WEDNESDAY NIGHT
FOR WYZ104-106-110-116-117.
WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR WYZ112.
WINTER STORM WARNING UNTIL 8 PM MST THIS EVENING FOR WYZ114.
NE...NONE.
SHORT TERM...RUBIN
LONG TERM...REC
AVIATION...GCC/REC
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