087
FXUS65 KCYS 312148
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
248 PM MST FRI JAN 31 2025
KEY MESSAGES
- HIGH WIND WARNINGS AND WATCHES IN EFFECT TODAY THROUGH
SATURDAY FOR THE SOUTHEAST WYOMING WIND PRONES AND ADJACENT
AREAS.
- WINTER STORM WARNINGS ISSUED FOR THE SIERRA MADRE AND SNOWY
RANGES SATURDAY MORNING THROUGH SUNDAY FOR HEAVY ACCUMULATING
SNOW AND WINDY CONDITIONS; WINTER WEATHER ADVISORIES FOR
CENTRAL CARBON COUNTY AND NORTH SNOWY RANGE FOOTHILLS
INCLUDING ARLINGTON FOR LIGHT BLOWING SNOW AND POOR
VISIBILITIES.
- WIDESPREAD ELEVATED TO STRONG WINDS CONTINUE INTO NEXT WEEK.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 213 PM MST FRI JAN 31 2025
THE LOW LEVEL JET IS ALREADY STARTING TO CRANK UP ACROSS THE
REGION AS OF THIS AFTERNOON, AND WINDS ARE ALREADY BEGINNING TO
INCREASE IN RESPONSE. ARLINGTON HAS ALREADY RECORDED GUSTS OF 57
MPH, WITH SEVERAL OTHER LOCATIONS INTO THE 40'S. WE WILL
CONTINUE TO SEE THESE PEAK AND OVERSPREAD AS THE JET CONTINUES
TO STRENGTHEN, STRONGEST OVERNIGHT TONIGHT INTO SATURDAY
MORNING. HIGH WIND WARNINGS HAVE CONTINUED TO BE ISSUED FOR OUR
WIND-PRONE AREAS AND JUST EASTWARD INCLUDING GOSHEN COUNTY, AND
THE EASTERN PORTION OF LARAMIE COUNTY HAS A WATCH OUT AS
UNCERTAINTY LIES IF WINDS CAN SPREAD THAT FAR EAST. THE NBM IS
ONLY PEAKING PROBABILITIES FOR GUSTS 50+ MPH AROUND 30-50%, BUT
THE CAVEAT TO THIS IS THAT THE BLEND HAS BEEN LOW ON ITS WIND
FORECAST. THEREFORE DUE TO THE UNCERTAINTY HELD, COULDN'T
JUSTIFY A WARNING AT THIS TIME, BUT HAVE ISSUED A WATCH STARTING
FOR THIS EVENING THAT CAN BE EVALUATED LATER FOR UPGRADE OR
CANCELLATION.
OUTSIDE OF THE STRONG WINDS, WINTRY PRECIP SAW A SLIGHT BUMP
ACROSS OUR SOUTHWESTERN MOUNTAIN ZONES WHERE WE HAD WATCH
PRODUCTS. ALTHOUGH SNOW RATIOS ARE LIKELY TOO HIGH FROM HOW WARM
THIS MOISTURE STREAM IS AND HAD TO BE TEMPERED DOWN, UPSLOPE
FLOW OVER THIS TERRAIN WITH PWAT VALUES 200-250% OF NORMAL HAVE
CAUSED A NOTABLE UPTICK TO QPF, AND EVEN TEMPERING THIS DOWN
STILL BROUGHT HIGHER TOTALS THAN THE PREVIOUS FORECAST BY
AROUND 1-2 INCHES. ALONGSIDE COLLABORATION WITH OUR NEIGHBORS
AND WITH THE THREAT OF BLOWING AND DRIFTING SNOW INCLUDING VERY
LIMITED VISIBILITIES, HAVE GONE AHEAD AND UPGRADED TO A WARNING
FOR THESE TWO ZONES. THE ADJACENT ZONES TO THE NORTH INCLUDING
RAWLINS AND ARLINGTON ALSO HAD WINTER WEATHER ADVISORIES ISSUED
FOR THE EVENT AS WE SEE GENERALLY LIGHT AMOUNTS OF SNOW
EXPECTED, AROUND 1-4 INCHES, BUT WITH THE STRONG WINDS EXPECTED
HERE PERIODS OF NOTABLY REDUCED VISIBILITIES WILL BE POSSIBLE.
OTHERWISE, UPSLOPE FLOW IS EXPECTED TO INITIALLY KEEP THIS
PRECIPITATION POTENTIAL RELEGATED TO THE WESTERN PORTIONS OF OUR
CWA. ONCE WE PUSH INTO SUNDAY THOUGH, THE ABUNDANT MOISTURE
SHOULD BE ABLE TO OVERCOME SHADOWING EFFECTS AND MORE WIDESPREAD
PRECIPITATION CHANCES WILL BE EXPECTED FOR ALL ZONES. WITH
TEMPERATURES NOTABLY ABOVE NORMAL BY AROUND 5 TO 10 DEGREES,
PARTICULARLY IN OUR EASTERN ZONES, SNOW LEVELS WILL JUMP TO
BETWEEN 5000-8000 FEET, SO THE BULK OF THIS ACTIVITY WILL BE
LIGHT RAIN.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
ISSUED AT 213 PM MST FRI JAN 31 2025
FAIRLY MUDDLED LONG TERM FORECAST, WITH A DECENT AMOUNT OF
UNCERTAINTY DUE TO MODEL TO MODEL DISAGREEMENT/VARIATIONS INTO NEXT
WEEK. OVERALL SYNOPTIC PATTERN WILL SEE THE TRANSITION FROM ZONAL
FLOW EARLY IN THE EARLY PORTION OF THE WEEK TO WEAK UPPER LEVEL
RIDGING SLOWLY DEVELOPING ACROSS THE INTERMOUNTAIN WEST AND HIGH
PLAINS BY MIDWEEK. UNDER THIS SETUP, PLENTY OF MOISTURE ADVECTION
INTO THE REGION AND RESULTANT HIGH PWATS TAKING LITTLE TO GET
PRECIPITATION GOING WITH PWAT STANDARDIZED ANOMALIES UP TO 2.5 SIGMA
ABOVE CLIMATOLOGY THROUGH THURSDAY, WITH A FAIRLY DECENT ATMOSPHERIC
RIVER SIGNATURE FLOWING FROM THE PACIFIC TO THE INTERMOUNTAIN WEST.
MAIN CONCERN IS WITH THE FLOW DIRECTION, KEEPING MUCH OF THE
PRECIPITATION CONFINED TO THE MOUNTAIN ZONES WHERE UPSLOPE FLOW WILL
LIKELY PLAY A ROLE. INTO THE LOWER AREAS, DOWNSLOPING COMPONENT TO
THE WINDS ALONG WITH HIGHER TEMPERATURES WILL LIMIT ANY SNOW
DEVELOPING AS TEMPERATURES ARE EXPECTED TO REMAIN WELL ABOVE
FREEZING. THE NAEFS MEAN 700MB TEMPERATURES HAVE BEGUN PICKING UP ON
THESE WARMER TEMPERATURES, WITH 700MB TEMPERATURES IN THE
CLIMATOLOGICAL 90TH PERCENTILE FOR THE SOUTHERN COUNTIES IN THE CWA
MONDAY, AND UPWARDS TO 99TH PERCENTILE TUESDAY THROUGH EARLY
WEDNESDAY BEFORE MORE SEASONABLE TEMPERATURES RETURN MID THROUGH
LATE WEEK. AS A RESULT, IN THE EVENT PRECIPITATION CAN GET GOING
WITH PLENTY OF MOISTURE WITHIN THE COLUMN TO PRODUCE RAIN/SNOW
ACROSS THE AREA, WILL LIKELY SEE BETTER SNOW CHANCES ACROSS THE
MOUNTAINS AND NORTHERN COUNTIES WHERE COLDER TEMPERATURES ARE
PROGGED. REGARDLESS, WILL NEED TO CONTINUE TO MONITOR SNOW CHANCES
INTO THE LOWER AREAS, ESPECIALLY IN THE AREAS THE NBM ADVERTISES
HIGHER POPS WHERE TEMPERATURES COULD WET-BULB TO 0C AND SNOW WILL
LIKELY ENSUE.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 942 AM MST FRI JAN 31 2025
LARGELY VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD FOR
THE MAJORITY OF TERMINALS. ANOTHER DAY OF ACTIVE WEATHER IS
EXPECTED WITH GUSTY TO STRONG WINDS POSSIBLE ACROSS SOUTHEAST
WYOMING AND MOUNTAIN WAVE SIGNATURES PROPAGATING STRONGER WINDS
DOWNSTREAM. INTO TONIGHT, LLWS WILL BE POSSIBLE WHILE THE
ATMOSPHERE IS EFFECTIVELY DECOUPLED, WITH A STRONG JET PASSING
OVERHEAD. MAIN UNCERTAINTY WILL BE WITH HOW LONG INTO THE
OVERNIGHT PERIOD THIS DECOUPLING TAKES PLACE, KEEPING WINDS FROM
REACHING THE SURFACE. IN ADDITION TO WINDS, PRECIPITATION
CHANCES INCREASE FOR AREAS WEST OF THE LARAMIE RANGE, WITH LIGHT
SNOW AND STRONG WINDS LEADING TO AREAS OF BLOWING SNOW AND
REDUCED VISIBILITY. AS A RESULT, IFR CONDITIONS WILL BE POSSIBLE
FOR KRWL EARLY TOMORROW MORNING.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 5 PM MST SATURDAY FOR WYZ101-106.
HIGH WIND WARNING UNTIL 5 AM MST SUNDAY FOR WYZ104-110.
HIGH WIND WARNING UNTIL 5 PM MST SATURDAY FOR WYZ107-108-116-
117.
WINTER WEATHER ADVISORY FROM 5 AM SATURDAY TO 5 PM MST SUNDAY
FOR WYZ109-110.
WINTER STORM WARNING FROM 5 AM SATURDAY TO 5 PM MST SUNDAY FOR
WYZ112-114.
HIGH WIND WARNING FROM 8 PM THIS EVENING TO 5 PM MST SATURDAY
FOR WYZ118.
HIGH WIND WATCH FROM 8 PM MST THIS EVENING THROUGH SATURDAY
AFTERNOON FOR WYZ119.
NE...NONE.
SHORT TERM...CG
LONG TERM...MRD
AVIATION...MRD
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