178
FXUS65 KCYS 192021
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
121 PM MST FRI DEC 19 2025
KEY MESSAGES
- A PARTICULARLY DANGEROUS SITUATION RED FLAG WARNING REMAINS IN
EFFECT FOR PORTIONS OF THE SOUTHERN LARAMIE RANGE AND
FOOTHILLS THROUGH LARAMIE COUNTY FOR EXTREME AND RAPID
WILDFIRE SPREAD.
- HIGH WINDS ARE ONGOING ACROSS THE CWA WITH MANY LOCATIONS
SEEING GUSTS IN EXCESS OF 60-85 MPH, LOCALLY HIGHER IN OUR
KNOWN WIND PRONE AREAS.
- STRONG WINDS COUPLED WITH LOW RELATIVE HUMIDITIES AND DRY
FUELS HAVE PROMPTED RED FLAG WARNINGS FOR MUCH OF SOUTHEASTERN
WYOMING AND THE NEBRASKA PANHANDLE THROUGH THIS EVENING.
- WINTER WEATHER ADVISORIES ARE IN EFFECT FOR THE SNOWY AND
SIERRA- MADRE RANGES DUE TO MODERATE AMOUNTS OF MOUNTAIN
SNOWFALL THIS EVENING THROUGH SATURDAY EVENING.
- WINDY CONDITIONS LOOK TO CONTINUE THROUGHOUT THE UPCOMING WORK
WEEK, WITH HIGH WINDS POSSIBLE SUNDAY AFTERNOON TO MONDAY
EVENING AND AGAIN THURSDAY.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 121 PM MST FRI DEC 19 2025
LETS CUT TO THE CHASE, DUE TO SEVERAL FACTORS, WE ARE UNDER A
PARTICULARLY DANGEROUS SITUATION (PDS) RED FLAG WARNING, COORDINATED
WITH THE SPC, FOR AN AREA ALONG THE FOOTHILLS OF THE LARAMIE RANGE
EAST INTO LARAMIE COUNTY, INCLUDING CHEYENNE, THROUGH THIS
EVENING. THIS IS WHERE CHANNELED FLOW, WHICH IS SUPPORTING
SUSTAINED WINDS 30-50 MPH ALONG WITH GUSTS APPROACHING 80 MPH,
DRY FUELS, AND SUB 20 PERCENT RH VALUES THAT ARE PRODUCING A
VOLATILE ENVIRONMENT FOR EXTREME FIRE WEATHER CONCERNS. THIS IS
ALL DUE TO A STOUT 700MB JET, 60-80 KNOTS, ALONG WITH ENOUGH
SUBSIDENCE TO ALLOW THESE WINDS TO MIX DOWN TO THE SURFACE INTO
A DRY BOUNDARY LAYER. THIS IS NOT THE ONLY AREA OF CONCERN, RED
FLAG WARNINGS ARE OUT THROUGH THIS EVENING FOR A LARGE CHUNK OF
THE CWA, FROM I-25 EAST INTO THE NEBRASKA PANHANDLE. WHICH IS
DUE TO A COMBINATION OF STRONG WINDS, WIDESPREAD 40 TO 50 MPH,
AND GUSTS APPROACHING 80 MPH, DRY CONDITIONS, AND RH VALUES
DIPPING TO AS LOW AS 10 PERCENT, ALL THIS IS BRINGING ADDITIONAL
FIRE WEATHER CONCERNS ACROSS THE REGION.
WITH ALL THAT FIRE WEATHER TALK OUT OF THE WAY, LETS TALK ABOUT
WINDS. ITS HOWLING OUT THERE WITH MANY AREAS SEEING SUSTAINED WINDS
40 TO 50 MPH, WITH GUSTS TOPPING OUT IN EXCESS OF 80 MPH. WHY, AS
MENTIONED ABOVE, WE HAVE A STRONG 700 MB JET ALONG WITH ENOUGH
SUBSIDENCE TO BRING THE STRONG WINDS TO THE SURFACE. IN ADDITION, AT
THE SURFACE WE HAVE A LEESIDE TROUGH AIDING IN THE STRONGER
WINDS WHICH WILL SPREAD INTO THE NEBRASKA PANHANDLE. THEREFORE,
WE HAVE HIGH WIND WARNINGS IN EFFECT INTO THE OVERNIGHT HOURS.
MANY LOCATIONS WILL SEE WINDS DIMINISH TO LESS THAN THE HIGH
WIND CRITERIA TONIGHT INTO SATURDAY MORNING FROM THE EASTERN
FORECAST ZONES INITIALLY AND THEN GRADUALLY INTO OUR WESTERN
FORECAST ZONES.
IN OTHER NEWS, TEMPERATURES WILL CLIMB INTO THE 50S AND 60S TODAY,
DIPPING INTO THE 20S TO LOW 30S TONIGHT. EXPECT COOLER TEMPERATURES
SATURDAY BEHIND A COLD FRONT THAT WILL DIVE SOUTH TONIGHT, MORE ON
THAT HERE IN A BIT. HIGHS SATURDAY LOOK TO TOP OUT ONLY IN THE UPPER
30S TO MID 40S WITH LOWS IN THE LOWER TO MID 20S. THIS COLD FRONT,
WILL DO WONDERS ACROSS THE CWA IN REGARDS OF WHAT WAS DISCUSSED
IN THE BEGINNING OF THIS SHORT TERM DISCUSSION. EXPECT AN END
TO THE WIDESPREAD STRONG WINDS AND FIRE WEATHER CONCERNS. THIS
FRONT WILL ALSO BRING IN INCREASED CHANCES OF PRECIPITATION, A
RAIN/SNOW MIX FOR LOWER ELEVATIONS AND A DECENT AMOUNT OF
MOUNTAIN SNOWFALL, UPWARDS OF A FOOT AT HIGHER ELEVATIONS IN THE
SNOWY AND SIERRA MADRE RANGES. HENCE, THE WINTER WEATHER
ADVISORIES THAT WE HAVE OUT INTO SATURDAY EVENING.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 121 PM MST FRI DEC 19 2025
WINDY CONDITIONS WILL PERSIST THROUGH MUCH OF THE UPCOMING WEEK,
WITH SEVERAL ROUNDS OF HIGH WINDS TO NEAR-HIGH WINDS EXPECTED. THE
UPPER-LEVEL PATTERN WILL REMAIN FAVORABLE FOR CONTINUED WINDY
CONDITIONS AND MINIMAL PRECIPITATION ACROSS MUCH OF THE CWA THROUGH
WEDNESDAY MORNING. THERE ARE TWO MAIN DAYS THAT LOOK TO FEATURE HIGH
WINDS OR NEAR-HIGH WINDS: SUNDAY AFTERNOON THROUGH MONDAY EVENING,
THEN AGAIN THURSDAY. UNSEASONABLY WARM TEMPERATURES WILL CONTINUE
THROUGH THE WEEK, WITH HIGHS CONSISTENTLY IN THE 50S AND 60S. MONDAY
AND WEDNESDAY WILL BE THE WARMEST DAYS, WITH PORTIONS OF THE WESTERN
NEBRASKA PANHANDLE APPROACHING 70F.
GETTING INTO THE WIND POTENTIAL FOR THE LONG TERM FORECAST, SUNDAY
AFTERNOON THROUGH MONDAY EVENING IS THE MOST FAVORABLE SETUP AT THIS
TIME. THURSDAY LOOKS GOOD AS WELL, BUT IS STILL 7 DAYS OUT, SO THE
EXACT INTENSITY OF THIS SETUP MAY CHANGE OVER THE NEXT SEVERAL DAYS.
STICKING TO THE SUNDAY AFTERNOON THROUGH MORNING EVENING TIMEFRAME,
UPPER-LEVEL ZONAL FLOW WILL DOMINATE THE REGION THROUGH THE SUNDAY
TO MONDAY TIMEFRAME. ZONAL FLOW AT 700MB IS ALSO EXPECTED AS A
SUBTLE SHORTWAVE MOVES ACROSS THE INTERMOUNTAIN WEST, TIGHTENING THE
HEIGHT GRADIENTS AND INCREASING THE 700MB JET TO 60 TO 65KTS ACROSS
THE LARAMIE RANGE AND 50 TO 55KTS ACROSS THE SNOWY AND SIERRA MADRE
RANGES. DUE WESTERLY 700MB WINDS ARE EXPECTED ACROSS THE LARAMIE
RANGE, WHILE SOUTHWESTERLY 700MB WINDS ARE EXPECTED ACROSS THE
SIERRA MADRE AND SNOWY RANGES, LEADING TO FAVORABLE WIND DIRECTIONS
FOR ALL THE TYPICAL WIND PRONE REGIONS: ARLINGTON/ELK MOUNTAIN, THE
I-80 SUMMIT, AND BORDEAUX ALONG I-25. GFS OMEGA FIELDS ARE ALSO
ONBOARD WITH THE MOUNTAIN WAVE SETUP FOR SUNDAY/MONDAY WITH MAXED
OUT DOWNWARD OMEGA VALUES ALONG THE LARAMIE RANGE AND THE SNOWY
RANGE THROUGH THE ENTIRE PERIOD SUNDAY AFTERNOON THROUGH MONDAY
EVENING. VERY STRONG LOW-LEVEL LAPSE RATES WILL ENABLE 700MB WINDS
TO MIX DOWN TOWARDS THE SURFACE WITH FORECAST INVERSION LEVELS VERY
SIMILAR TO THE INVERSION LEVELS TODAY, DECEMBER 19TH. IN HOUSE
RANDOM FOREST GUIDANCE IS ALSO ONBOARD WITH HIGH WINDS AT THE
TYPICAL WINDY AREAS WITH 40 TO 60% PROBABILITY OF HIGH WINDS. CRAIG
TO CASPER GRADIENTS ARE A TOUCH LOW AT THIS TIME, BUT CONDITIONS MAY
CHANGE OVER THE NEXT COUPLE OF DAYS.
BREEZY CONDITIONS WILL PERSIST TUESDAY AND WEDNESDAY BEFORE THE NEXT
CHANCE FOR HIGH WIND CRITERIA WINDS ON THURSDAY. FOR THURSDAY,
SOUTHWESTERLY UPPER-LEVEL FLOW WILL DOMINATE THE INTERMOUNTAIN WEST
BEHIND A SLOWLY MIGRATING RIDGE, WITH ZONAL FLOW POTENTIALLY RETURN
BY THURSDAY EVENING. CURRENT LONG RANGE MODELS SUGGEST THE
DEVELOPMENT OF A STRONG CANADIAN LOW OVER CENTRAL CANADA, INCREASING
THE HEIGHT GRADIENTS ACROSS THE CWA AND FUNNELING 700MB WINDS INTO A
MORE ZONAL ORIENTATION. THE GFS CURRENTLY SUGGESTS A 700MB JET OVER
70KTS ACROSS THE LARAMIE RANGE, WITH MAXED OUT DOWNWARD OMEGA VALUES
IN THE SAME LOCATION. THIS SETUP WOULD FAVOR ANOTHER ROUND OF
WIDESPREAD HIGH WINDS, BUT THINGS MAY CHANGE AS THURSDAY IS STILL 7
DAYS AWAY. IN-HOUSE RANDOM FOREST GUIDANCE IS HINTING AT THE
POSSIBILITY OF THE THURSDAY HIGH WIND EVENT, WITH PROBABILITIES
CURRENTLY AROUND 60%. THIS SETUP WILL CONTINUE TO BE MONITORED OVER
THE NEXT SEVERAL DAY TO DETERMINE HOW MUCH PARAMETERS CHANGE.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1020 AM MST FRI DEC 19 2025
STRONG WINDS WILL IMPACT ALL TERMINALS ACROSS THE CWA AT VARYING
TIMES AND INTENSITY THROUGH MOST OF THIS TAF PERIOD. EXPECT GUSTS TO
AROUND 60 TO 70 KNOTS, POSSIBLY HIGHER, THROUGH ABOUT 06Z SATURDAY
ALONG WITH LLWS IMPACTING AVIATION OPERATIONS. THEREAFTER, WINDS WILL
BE ON THE DOWNWARD TREND TO LESS THAN 25 KNOTS, STRONGEST FOR
TERMINALS WEST OF I-25, WHILE THE NE PANHANDLE TERMINALS DROP TO
LESS THAN 15 KNOTS. FOR CIGS AND VIS, VFR CONDITIONS WILL PREVAIL
ACROSS ALL TERMINALS THROUGH THIS EVENING. OVERNIGHT, A FRONT WILL
DROP SOUTH AND INCREASE CHANCES OF PRECIPITATION, SO CIGS AND VIS
MAY DROP TO MVFR OR LOWER WHICH WILL ROUND OUT THIS TAF PERIOD.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL MIDNIGHT MST TONIGHT FOR WYZ417-418-
429>433.
HIGH WIND WARNING UNTIL 11 PM MST THIS EVENING FOR WYZ102-108-
119.
HIGH WIND WARNING UNTIL 5 AM MST SATURDAY FOR WYZ101-103-
105>107-109-113-115-117-118.
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...RED FLAG WARNING UNTIL MIDNIGHT MST TONIGHT FOR NEZ434>437.
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR NEZ002-003.
HIGH WIND WARNING UNTIL 11 PM MST THIS EVENING FOR NEZ019-020-
054-095-096.
SHORT TERM...RZ
LONG TERM...AM
AVIATION...RZ
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