161
FXUS65 KCYS 181149
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
449 AM MST THU DEC 18 2025
KEY MESSAGES
- WIDESPREAD STRONG TO LOCALLY DAMAGING WINDS WILL CONTINUE
THROUGH THE LATE MORNING HOURS ACROSS MUCH OF THE CWA.
- A LACK OF SIGNIFICANT MOISTURE COMBINED WITH STRONG WINDS AND
NEAR CRITICAL RELATIVE HUMIDITIES HAS PROMPTED A RED FLAG
WARNING FOR THURSDAY, AND A FIRE WEATHER WATCH FOR FRIDAY.
- ANOTHER SIGNIFICANT WIND EVENT IS EXPECTED THURSDAY NIGHT INTO
FRIDAY, POSSIBLY LINGERING INTO EARLY SATURDAY. WIND GUSTS
POSSIBLY EXCEEDING 90 MPH ARE EXPECTED ONCE AGAIN ALONG
PORTIONS OF THE I-25 CORRIDOR WITH WIDESPREAD 60 TO 80 MPH
GUSTS ELSEWHERE.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 305 AM MST THU DEC 18 2025
THE FORECAST JUST DOESN'T GET ANY EASIER AS WE CONTINUE WITH THE
ONGOING HIGH WIND PRODUCTS ACROSS THE REGION, WITH FURTHER WIND
CONCERNS AS WE MOVE THROUGH THE DAY AND INTO FRIDAY. THROUGH THE
LATE MORNING HOURS STRONG WINDS SHOULD PERSIST ACROSS MOST OF
THE EASTERN HALF OF THE CWA ALONGSIDE OUR USUAL WINDY LOCATION
OF THE ARLINGTON AREA. IN FACT, THIS LOCATION WAS OUR WINNER OF
YESTERDAY WITH A PAIR OF VERIFIED WIND GUSTS OVER 100 MPH! BY
THE LATE MORNING HOURS MOST LOCATIONS SHOULD SEE CONDITIONS BACK
BELOW HIGH WIND CRITERIA, BUT THIS WILL BE A BRIEF RESPITE AT
BEST.
ACCOMPANYING THESE WINDS THROUGH THE MORNING AND AFTERNOON
HOURS WILL BE A CRITICAL ENVIRONMENT FOR FIRE WEATHER
CONDITIONS. WHILE THE OVERALL CONDITIONS WON'T REACH OUR USUAL
CRITERIA FOR RED FLAG CONDITIONS (WINDS GUSTS 25+ MPH, RH VALUES
15% OR LESS), YESTERDAY PROVED THAT VERY HIGH WINDS AND MODEST
RH VALUES ALONGSIDE HOW DRY THE GRASSES ACROSS THE HIGH PLAINS
ARE IS MORE THAN ENOUGH TO CREATE A CRITICAL ENVIRONMENT.
WORKING WITH OUR NEIGHBORS TO THE SOUTH, WE HAVE ISSUED A RED
FLAG WARNING VALID STARTING AT 5 AM THIS MORNING AND CONTINUING
THROUGH THE AFTERNOON HOURS. ANY NEW FIRES THAT DO START WILL
SPREAD RAPIDLY.
THIS EVENING STARTS THE NEXT ROUND OF HIGH WINDS FOR THE CWA AND
WILL CONTINUE THROUGH LATE FRIDAY INTO SATURDAY MORNING. AT THE
UPPER LEVELS, A PACIFIC TROUGH MOVING INLAND WILL TIGHTEN THE
PRESSURE GRADIENT AND BRING A STOUT JET OVER THE CWA YET AGAIN.
MOVING FURTHER DOWN, AT 700MB THE JET WILL ONCE AGAIN INTENSIFY
WITH SPEEDS OF 90-95+ KNOTS NOTED ON THE GFS, AND THEN AT THE
SURFACE CRAIG TO CASPER PRESSURE GRADIENTS ONCE AGAIN IN EXCESS
OF 85-90 METERS. OF NOTE, THE PREVIOUS DISCUSSION MENTIONED THE
INVERSION AT THE 650-600MB LEVEL BEING A LITTLE HIGHER WHICH
MIGHT PREVENT SOME OF THE MOUNTAIN WAVE BREAKING WE HAD SEEN
YESTERDAY, BUT LATEST ANALYSIS OF SOME OF THE HIGH RESOLUTION
GUIDANCE INDICATES WE MAY ACTUALLY SEE THAT A LITTLE LOWER NEAR
675 OR EVEN 700 MB, WHICH WOULD PUT US IN A SIMILAR POSITION FOR
THE EXCESSIVE WIND SPEEDS WE JUST SAW. IN EITHER CASE, A
SIMILAR EVENT OF WIDESPREAD GUSTS 60-80 MPH IS EXPECTED FOR THE
CWA, WITH LOCALIZED GUSTS 80-90+ MPH EXPECTED FOR OUR WIND PRONE
LOCATIONS. HIGH WIND WATCHES BEGINNING THIS EVENING AND
CONTINUING THROUGH SATURDAY MORNING HAVE BEEN ISSUED, AND AS OF
THIS WRITING THE PLAN IS TO BEGIN UPGRADING THOSE POSSIBLY AS
EARLY AS LATER THIS MORNING.
ONCE AGAIN WE ARE FACING ANOTHER ROUND OF CRITICAL FIRE WEATHER
CONDITIONS ON FRIDAY AS WELL, AND YET AGAIN IN TANDEM WITH OUR
NEIGHBORING OFFICE TO THE SOUTH, HAVE ISSUED FIRE WEATHER
WATCHES, THIS TIME FOR A MUCH LARGER PORTION OF OUR HIGH PLAINS
AREAS IN WYOMING AND NEBRASKA. PORTIONS OF THIS WATCH MAY EVEN
REACH OUR STANDARD THRESHOLD FOR A RED FLAG WARNING, BUT IN ANY
CASE THE DANGER OF VERY HIGH WINDS ALONGSIDE LOW RH VALUES AND A
LACK OF NOTABLE MOISTURE WILL FUEL FURTHER FIRE WEATHER DANGER
FOR THE AREA.
FINALLY, BEHIND THE COLD FRONT TODAY, TEMPERATURES WILL BE
CLOSER TO WHAT WE WOULD EXPECT FOR DECEMBER, WITH HIGHS IN THE
30'S TO 40'S AFTER WIDESPREAD SUB-FREEZING LOWS THIS MORNING.
BUT WITH THE RIDGE GETTING A QUICK RESURGENCE ON FRIDAY, EXPECT
THOSE WINTER-LIKE TEMPERATURES TO QUICKLY SPIKE BACK INTO THE
50'S TO 60'S (WHICH WILL ALSO FUEL OUR DRY CONDITIONS AS RH
VALUES DROP IN RESPONSE). OVERNIGHT INTO SATURDAY MORNING THE
NEXT FRONT WILL APPROACH AND MOVE ACROSS THE REGION WITH
PRECIPITATION CHANCES ACCOMPANYING IT. WHILE SOME LIGHT TO
OCCASIONALLY MODERATE RAIN, POSSIBLY WITH SNOW MIXING IN OR
TRANSITIONING OVER TO, WILL BE POSSIBLE, NOT SEEING THE SIGNAL
FOR THE STRONGER BANDS THAT PRODUCED SNOW SQUALLS YESTERDAY. FOR
NOW, HOLDING OFF ON MESSAGING THIS, BUT WE'LL LIKELY SEE SEVERAL
INCHES OF SNOW IN THE MOUNTAINS WITH A POSSIBLE ADVISORY NEEDED,
WITH THE LOWER ELEVATIONS GETTING A SMALL HIT OF MOISTURE, BUT
LIKELY MISSING MUCH OF THE REGION EAST OF I-25.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
ISSUED AT 430 PM MST WED DEC 17 2025
A BROAD RIDGE WILL BE THE DOMINATE PATTERN FOR THE
LONG TERM. FRIDAY NIGHT INTO SATURDAY, AN ALBERTA CLIPPER WILL MOVE
ACROSS THE US/CANADA BORDER COMPRESSING THE PRESSURE GRADIENT
AGAINST OUR BROAD RIDGE. THIS IN TURN WILL SUSTAIN OUR 700MB JET
INTO THE 60 TO 70KTS RANGE. CONCURRENTLY THE GLOBAL MODEL OMEGA
FIELDS ARE STILL SHOWING MAXED OUT DOWNWARD OMEGAS INDICATIVE OF
ANOTHER HIGH WIND EVENT CONTINUING THROUGH THE OVERNIGHT PERIOD. OUR
IN HOUSE ALGORITHM ALSO AGREES AS IT GIVES A 75 TO 80 PERCENT PROB
OF ACHIEVING A HIGH WIND CRITERIA. THE HIGH WIND FORECAST GETS A
LITTLE TRICKY THROUGH THE WEEKEND AS THERE IS A LITTLE BIT OF TIMING
DISAGREEMENT WITH THE ARRIVAL OF THE NEXT WAVE BETWEEN THE GLOBAL
MODELS. TO ADD TO THE UNCERTAINTY, THE ENSEMBLE CLUSTER ANALYSIS
DEPICTED ABOUT EQUAL CHANCES FOR THE GFS SOLUTION OF A MORE
PROGRESSIVE SYSTEM LIMITING THE LULL IN HIGH WINDS SATURDAY INTO
SUNDAY, AND THE EURO DELAYED SOLUTION THAT HAS THE WAVE ARRIVING
ABOUT LATE SUNDAY NIGHT INTO MONDAY MORNING. BEHIND THIS WAVE THE
700MB JET LOOKS TO BE AROUND 55 TO 60KTS WHICH WOULD BE ENOUGH TO
ACHIEVE HIGH CRITERIA. SO DEPENDING ON THE TIMING OF THIS WAVE WE
COULD SEE A LULL IN HIGH WINDS SATURDAY AFTERNOON THROUGH SUNDAY
MORNING. THE GLOBAL OMEGA FIELDS HAVE SOME DOWNWARD MOTION BUT THE
700MB JET ISN'T PORTRAYED AS HAVING SUSTAINED WINDS OF 55KTS OR
HIGHER DURING THAT TIME. BUT TO ADD SOME CONFIDENCE IN THE LULL IN
HIGH WINDS. OUR IN-HOUSE ALGORITHM SHOWS HIGHER CONFIDENCE WITH 40
TO 60 PERCENT PROBS OF ELEVATED WINDS AS OPPOSED TO WINDS THAT MEET
THE HIGH WIND CRITERIA. AFTER THE OPEN WAVE MOVES THROUGH THE WINDS
ON THE BACKSIDE LOOK CURRENTLY MORE ELEVATED WITH THE 700MB JET
BEING BETWEEN 40-55KTS. SO THE WINDS LOOK TO REMAIN GUSTY THROUGH
THE START OF THE WORK WEEK AT THE VERY LEAST. TEMPERATURES ON THE
OTHER HAND LOOK TO REMAIN IN THE HIGH 50'S TO LOW 60'S THROUGHOUT
THE LONG TERM AS THIS RIDGE IS FORECASTED TO REMAIN ANCHORED OVER
THE WEST HALF OF THE UNITED STATES. OVERNIGHT TEMPERATURES WILL DROP
INTO THE HIGH TWENTIES SATURDAY NIGHT MAKING IT THE COLDEST NIGHT AS
THE REST OF THE FORECASTED TEMPERATURES LOOK TO BE IN THE 30'S
POSSIBLY 40'S THROUGH CHRISTMAS DAY.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 446 AM MST THU DEC 18 2025
VFR CONDITIONS EXPECTED OVER THE NEXT 24 HOURS. WINDS REMAIN THE
PRIMARY HAZARD AS WIDESPREAD GUSTS OF 30-50 KNOTS PERSIST INTO
THIS EVENING FOR WY TERMINALS, WHILE NE TERMINALS SHOULD SEE A
BREAK FROM WINDS DURING THE AFTERNOON AND EVENING AS WINDS CALM
DOWN TO AROUND 12-15 KNOTS OR LESS. WINDS RESUME GUSTING FOR
ALL TERMINALS BY TOMORROW MORNING THOUGH, WITH GUSTS 25-50 KNOTS
BY THE END OF THE TAF PERIOD, ALONGSIDE LOW LEVEL WIND SHEAR.
CIGS EXPECTED TO BE AROUND MID TO HIGH LEVELS AT FEW TO SCT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 11 AM MST THIS MORNING FOR WYZ102-
106>108-110-116>119.
FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR WYZ430>433.
RED FLAG WARNING UNTIL 5 PM MST THIS AFTERNOON FOR WYZ430-431.
HIGH WIND WATCH FROM THIS EVENING THROUGH LATE FRIDAY NIGHT
FOR WYZ101-107-118.
HIGH WIND WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING FOR
WYZ102-108-119.
HIGH WIND WATCH FROM THIS EVENING THROUGH LATE FRIDAY NIGHT
FOR WYZ103-105-106-109-113-115-117.
HIGH WIND WATCH FROM THIS AFTERNOON THROUGH SATURDAY MORNING
FOR WYZ104-110-116.
NE...HIGH WIND WARNING UNTIL 11 AM MST THIS MORNING FOR NEZ002-003-
019>021-054-055-095-096.
FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR NEZ436-437.
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR
NEZ019-020-054-095-096.
RED FLAG WARNING UNTIL 5 PM MST THIS AFTERNOON FOR NEZ437.
UPDATE...MN
SHORT TERM...CG
LONG TERM...MM
AVIATION...CG
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