631
FXUS65 KCYS 191111
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
411 AM MST FRI DEC 19 2025
KEY MESSAGES
- A PARTICULARLY DANGEROUS SITUATION RED FLAG WARNING HAS BEEN
ISSUED FOR PORTIONS OF THE SOUTHERN LARAMIE RANGE AND
FOOTHILLS THROUGH LARAMIE COUNTY FOR EXTREME AND RAPID
WILDFIRE SPREAD.
- ANOTHER HIGH WIND EVENT IS ONGOING ACROSS THE CWA WITH MOST
OF THE REGION EXPECTED TO SEE STRONG WIND GUSTS IN EXCESS OF
60-85 MPH, WITH SOME HIGHER GUSTS POTENTIALLY FOR OUR WIND
PRONE LOCATIONS.
- HIGH WINDS ALONGSIDE LOW DAYTIME RELATIVE HUMIDITIES AND A
LACK OF MOISTURE ON FUELS HAS PROMPTED A RED FLAG WARNING FOR
MUCH OF SOUTHEASTERN WYOMING AND THE NEBRASKA PANHANDLE.
- A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE SNOWY AND
SIERRA-MADRE RANGES FOR MODERATE AMOUNTS OF MOUNTAIN SNOWFALL
FRIDAY EVENING THROUGH SATURDAY EVENING.
- BREEZY CONDITIONS ARE EXPECTED BEYOND SATURDAY ACROSS THE CWA,
BUT NOT NEARLY AS SIGNIFICANT AS DAYS PRIOR.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 408 AM MST FRI DEC 19 2025
LIKE DEJA VU, ONCE AGAIN WE'RE ON THE PRECIPICE OF A SIGNIFICANT
HIGH WIND EVENT ACROSS THE CWA. STRONG GUSTS ARE ALREADY ONGOING
ACROSS OUR WIND PRONE LOCATIONS AND THROUGH MUCH OF THE I-80
CORRIDOR FROM CHEYENNE WEST THROUGH RAWLINS, WITH MORE LOCATIONS
LIKELY TO SEE INCREASED STRONG WINDS AS THE DAY PRESSES ON. THE
700MB JET SHOULD REALLY GET HOWLING HERE IN A FEW HOURS AS
MODELS INDICATE SPEEDS PEAKING AROUND 90-95 KNOTS ALOFT
ALONGSIDE FAVORABLE SUBSIDENCE TO BRING THESE WINDS TO THE
SURFACE. ALONGSIDE THIS, HIGH RESOLUTION GUIDANCE IS SHOWING THE
INVERSION IS COMING DOWN A BIT LOWER THAN EXPECTED AND BACK
AROUND THE 700-650 MB RANGE, WHICH MAY PROMOTE MOUNTAIN WAVES
BREAKING SIMILAR TO OUR LAST BIG EVENT ON WEDNESDAY. IF THIS
COMES TO FRUITION, GUSTS OF 95 TO EVEN 100 MPH CAN'T BE RULED
OUT ONCE AGAIN.
MEANWHILE, TODAY'S WINDS WILL ALSO BRING A NOTABLE INCREASE IN
TEMPERATURES COMPARED TO YESTERDAY, WITH VALUES ALREADY BACK IN
THE 40'S TO EVEN 50'S ALONG THE I-25 CORRIDOR, AND SHOULD
CONTINUE TO SPREAD EASTWARDS AS WESTERLY WINDS MOVE OVER THE
AREA. WITH THIS RISE IN TEMPERATURES EAST OF THE LARAMIE RANGE
ALONGSIDE A LACK OF MOISTURE, RH VALUES WILL PLUMMET BACK INTO
THE TEENS AND 20'S. AND WITH STRONG WINDS OVERSPREADING YET
AGAIN AND FUELS SEEING NO SIGNIFICANT MOISTURE, A RED FLAG
WARNING WAS NECESSARY TO ACCOUNT FOR THE THREAT OF SIGNIFICANT
FIRE SPREAD YET AGAIN. WORKING ALONGSIDE OUR PARTNERS IN THE
SPC, WE HAVE IDENTIFIED A STRIP OF CRITICAL FIRE WEATHER
CONCERNS, PRIMARILY ALONG THE FOOTHILLS OF THE LARAMIE RANGE AND
EASTWARDS INTO LARAMIE COUNTY, WHERE CONDITIONS MAY BECOME
EXTREME FOR FIRE WEATHER SPREAD. BECAUSE OF THIS, A PARTICULARLY
DANGEROUS SITUATION (PDS) RED FLAG WARNING WAS NEEDED DUE TO
THE EXPECTED ENVIRONMENT TODAY. ANY WILDFIRES THAT OCCUR IN THIS
AREA WILL SPREAD VERY, VERY RAPIDLY. TO PUT THIS IN PERSPECTIVE,
OUR PARTNERS TO THE SOUTH AT BOULDER HAVE ISSUED A PDS WARNING
AS WELL, WITH DISCUSSIONS ON THE SIMILARITY TO CONDITIONS THAT
SPARKED THE MARSHALL FIRE SEVERAL YEARS AGO.
TONIGHT A COLD FRONT MOVES ACROSS THE REGION AND WILL BEGIN TO
SHUTOFF STRONG WIND FLOW, BUT WARNINGS REMAIN IN PLACE FOR MUCH
OF WYOMING THROUGH THIS EVENING AND INTO THE MORNING HOURS
TOMORROW. WITH THIS SYSTEM WILL COME A FRESH BATCH OF
PRECIPITATION INCLUDING MOUNTAIN SNOWFALL AND A RAIN/SNOW MIX
ACROSS OUR LOWER ELEVATION ZONES. WHILE OVERALL ACCUMULATIONS
SHOULD BE ON THE LOWER SIDE, SOME MODERATE AMOUNTS SHOULD OCCUR
FOR THE HIGHER ELEVATIONS OF THE SIERRA-MADRE AND SNOWY RANGES,
WITH A WINTER WEATHER ADVISORY FOR 5-10 INCHES OUT. BEHIND THE
FRONT, COOLER TEMPERATURES RETURN AS HIGHS DROP BACK INTO THE
30'S TO 40'S ON SATURDAY, WITH MUCH CALMER CONDITIONS EXPECTED
BY THE AFTERNOON AND EVENING AS WINDS BEGIN TO SETTLE.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 222 PM MST THU DEC 18 2025
WESTERN RIDGING REMAINS SUPPRESSED WITH ALASKAN TROUGHING ATTEMPTING
TO KINK THE FLOW AND FORCE SOME RIDING BACK INTO THE WESTERN CONUS
BY SUNDAY. REGARDLESS FLOW REMAINS PRIMARILY ZONAL THROUGH EARLY
NEXT WEEK BEFORE IT BECOMES MORE SW ALOFT. BY TUESDAY PACIFIC
TROUGHING BECOMES SO PRONOUNCED THAT THE RIDGE AXIS SHIFTS ALL THE
WAY EAST OF THE ROCKIES AND ORIENTED FROM EASTERN TEXAS NORTHWARDS
TO MONTANA/THE DAKOTAS. CURRENT CLUSTER ANALYSIS DOES SHOW A NUMBER
OF WAVES AMID THE SW FLOW BETWEEN SUNDAY AND NEXT THURSDAY BUT FOR
ONE REASON OR ANOTHER THE ASSOCIATED MOISTURE LOOKS TO REMAIN WELL
WEST OF US UNTIL THURSDAY, MEANING NO WHITE CHRISTMAS FOR MOST
UNLESS YOU LIVE ABOVE 8,000FT WHERE THERE IS CURRENTLY SNOWPACK.
TEMPERATURES ALSO WILL NOT FEEL VERY WINTER/CHRISTMAS LIKE WITH
DAILY HIGHS RANGING FROM THE 40S AND 50S ON SUNDAY TO 50S AND 60S
FOR THE WORK(HOLIDAY) WEEK.
NOW THE QUESTION ON EVERYONE'S MIND... WILL WE GET AN EARLY
CHRISTMAS PRESENT FROM MOTHER NATURE AND SEE THE WIND MACHINE TURN
OFF? SOMEWHAT SURPRISINGLY ACTUALLY YES. WHILE SUNDAY INTO MONDAY
LOOKS TO HAVE AT LEAST A CHANCE IN THE WIND PRONES ANYTHING BLEEDING
INTO THE ADJACENT AREAS AND ESPECIALLY HIGH PLAINS ALONG AND EAST OF
I25 LOOKS MUCH LESS OF A SLAM DUNK. ENSEMBLES DO SHOW MEMBERS WITH
700MB WINDS INTO THE 50-60KT RANGE BUT HIGHER THAN 60KTS SEEMS TIED
TO MOUNTAIN WAVE ACTIVITY ALONG THE NORTHERN LARAMIE RANGE UP NEAR
DOUGLAS AND CHUGWATER. OVERALL THE FACT THAT THIS WILL BE SW FLOW
ALOFT AND NOT WESTERLY WILL LIKELY LIMIT THE AREAS THE SEE HIGH
WINDS AND SHOULD FAVOR THOSE NORTHERN AREAS MORE FOR THIS EVENT (AND
OF COURSE THE WIND PRONE AREA OF ARLINGTON.) AS WE GET CLOSER TO THE
EVENT THINGS SHOULD BECOME CLEARER THAN THE MUD THEY CURRENTLY ARE.
BEYOND THIS WEEKEND/EARLY WEEK WIND HOWEVER THINGS LOOK MUCH MORE
PLEASANT WITH DAILY PEAK GUSTS IN THE WIND PRONES LIKELY IN THE 40-
50MPH RANGE AND ADJACENT AREAS SEEING GUSTS ONLY UP TO 30MPH.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1014 PM MST THU DEC 18 2025
ANOTHER VERY WINDY AVIATION FORECAST FOR THE 06Z TAF PERIOD. LOW-
LEVEL WIND SHEAR IS EXPECTED ACROSS ALL TERMINALS, PEAKING AROUND
70KTS. SURFACE WINDS ACROSS SOUTHEAST WYOMING WILL GUST BETWEEN 50
AND 60KTS, WITH NEBRASKA SITES GUSTING 50 TO 55KTS. LOW-LEVEL WIND
SHEAR EXPECTED TO CONTINUE THROUGHOUT THE TAF PERIOD. MID-LEVEL
CLOUDS WILL MOVE INTO THE REGION THIS AFTERNOON WITH MINIMAL
PRECIPITATION CHANCES.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING FROM 10 AM THIS MORNING TO 11 PM MST THIS
EVENING FOR WYZ417-418-430>433.
HIGH WIND WARNING UNTIL 5 AM MST SATURDAY FOR WYZ101-103-
105>107-109-113-115-117-118.
HIGH WIND WARNING UNTIL 11 PM MST THIS EVENING FOR WYZ102-108-
119.
HIGH WIND WARNING UNTIL 11 AM MST SATURDAY FOR WYZ104-110-116.
WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM MST
SATURDAY FOR WYZ112-114.
NE...HIGH WIND WARNING FROM 8 AM THIS MORNING TO 5 PM MST THIS
AFTERNOON FOR NEZ002-003.
RED FLAG WARNING FROM 10 AM THIS MORNING TO 11 PM MST THIS
EVENING FOR NEZ434>437.
HIGH WIND WARNING FROM 8 AM THIS MORNING TO 11 PM MST THIS
EVENING FOR NEZ019-020-054-095-096.
SHORT TERM...CG
LONG TERM...WFOCYS
AVIATION...AM
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