541
FXUS65 KCYS 150942
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
242 AM MST MON DEC 15 2025
KEY MESSAGES
- WARMING TREND EXPECTED TO CONTINUE THROUGH EARLY THIS WEEK
WITH STRONG WINDS RETURNING TO SOUTHEAST WYOMING LATE THIS
EVENING THROUGH THURSDAY. HIGH WIND WATCHES AND WARNING ARE
IN EFFECT FOR THE WIND PRONE AREAS STARTING THIS EVENING.
- A MORE WIDESPREAD STRONG WIND EVENT IS POSSIBLE ACROSS MOST
OF SOUTHEAST WYOMING ON WEDNESDAY.
- NEXT CHANCE FOR PRECIPITATION ON WEDNESDAY WITH PERIODS OF SNOW
AND RAIN POSSIBLE.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 240 AM MST MON DEC 15 2025
QUIET AND RELATIVELY MILD WEATHER EARLY THIS MORNING WITH
CURRENT TEMPERATURES IN THE 40S AND 50S OVER MOST OF SOUTHEAST
WYOMING. SOME OF THE HIGHER VALLEYS SHOW TEMPERATURES IN THE
20S, BUT OVERALL A PRETTY MILD MORNING ACROSS THE AREA. THE
COLDEST AREA IS THE WESTERN NEBRASKA PANHANDLE WHICH HAS TEMPS
AS LOW AS 17 DEGREES. EXPECT THESE LOWER TEMPERATURES TO
INCREASE SOMEWHAT AS WE HEAD TOWARDS SUNRISE WITH SOME WARM AIR
ADVECTION. SUCH MILD TEMPERATURES FOR MID DECEMBER ARE DUE TO
THE LARGE AREA OF HIGH PRESSURE ALOFT TO THE SOUTH, RESULTING IN
A THERMAL RIDGE OVER THE FRONT RANGE AND 700MB TEMPERATURES AS
HIGH AS 8C TO 10C.
ALL MODELS IN PRETTY GOOD AGREEMENT TODAY AND TUESDAY. OTHER
THAN A RETURN TO WINDY CONDITIONS ON TUESDAY, MILD WEATHER IS
EXPECTED TO CONTINUE OVER THE WHOLE AREA THROUGH TUESDAY
EVENING. AFTERNOON HIGHS MONDAY WILL BE SIMILAR TO SUNDAY, WITH
READINGS WELL INTO THE 60S FOR MANY PLACES, AND LOW TO MID 50S
FOR RAWLINS, SARATOGA, AND LARAMIE...WHICH IS STILL 20 TO 25
DEGREES ABOVE AVERAGE. EXPECT ANOTHER ROUND OF RECORD HIGH
TEMPERATURES FOR SOUTHEAST WYOMING AND A FEW MIGHT DROP FOR
WESTERN NEBRASKA AS WELL. TUESDAY WILL BE A FEW DEGREES COOLER
COMPARED TO MONDAY, MAINLY BECAUSE OF INCREASING CLOUD COVER
AND A WEAK LOW TO MIDLEVEL COOL FRONT MOVING ACROSS THE REGION.
OTHERWISE, NO PRECIPITATION IS EXPECTED THROUGH TUESDAY NIGHT.
PRIMARY FORECAST CONCERN WILL BE STRONG WINDS DEVELOPING OVER
THE WIND PRONE AREAS AS EARLY AS LATE THIS AFTERNOON. MODELS AND
IN-HOUSE WIND GUIDANCE CONTINUES TO SHOW PROBABILITY OF STRONG
WINDS (40+ MPH SUSTAINED/58+ MPH GUSTS) ABOVE 75% FOR SEVERAL
WIND PRONE AREAS ALONG I-80. EXPECT THE LOW TO MIDLEVEL PRESSURE
GRADIENT ALONG THE SPINE OF THE MOUNTAINS TO INCREASE IN
RESPONSE TO THE NEXT PACIFIC SYSTEM MOVING INTO MONTANA AND
NORTHERN WYOMING OVER THE NEXT 24 TO 30 HOURS. ALTHOUGH 700MB
WINDS ARE NOT QUITE AS STRONG AS LAST NIGHT, THEY ARE STILL OVER
50 TO 55 KNOTS FOR THE DURATION OF THE EVENT. GFS AND NAM SHOW
PLENTY OF 700MB SUBSIDENCE TONIGHT ACROSS THE WIND PRONE
AREAS...PEAKING BETWEEN 600 AM AND NOON TUESDAY, WITH AN EVEN
LARGER SIGNATURE LATE TUESDAY AND WEDNESDAY. WITH WINDS EARLY
THIS MORNING ALREADY GUSTING BETWEEN 40 TO 45 MPH ACROSS THE
WIND PRONE AREAS WITH MEAGER PRESSURE GRADIENTS AND FORCING,
DECIDED TO ISSUE A HIGH WIND WARNING FOR THE ARLINGTON/ELK
MOUNTAIN ARE STARTING THIS EVENING AT 5 PM, AND ISSUED A HIGH
WIND WATCH FOR THE CENTRAL AND SOUTHERN LARAMIE RANGE INCLUDING
BORDEAUX AND THE I-80 SUMMIT/FOOTHILLS. WENT WITH A WARNING FOR
ARLINGTON SINCE THIS EVENT MIGHT START AT ANY TIME OVER THE NEXT
12 HOURS, BUT DECIDED ON A WATCH FOR THE LARAMIE RANGE SINCE
THE ONSET OF WINDS MAY BE DELAYED BY 6 TO 12 HOURS. KEPT THE
HIGH WIND HEADLINES GOING THROUGH MOST OF TUESDAY. THERE IS A
BIT OF A BREAK BETWEEN THIS EVENT AND THE STRONGER EVENT ON
WEDNESDAY BASED ON CURRENT MODEL TRENDS, SO WILL MESSAGE EACH
EVENT SEPARATELY. FOR TUESDAY, SOME OF THESE WINDS WILL MIX
DOWN TO THE SURFACE FOR THE LOWER ELEVATIONS OF SOUTHEAST
WYOMING. WILL NEED TO WATCH THIS TREND SINCE SOME ENSEMBLE
GUIDANCE IS SHOWING WIND GUSTS NEARING 55 TO 60 MPH FOR LARAMIE,
CHEYENNE, AND EASTERN PLATTE COUNTY/JUST NORTH OF WHEATLAND.
INCREASED WINDS A BIT FOR WINDY CONDITIONS, BUT KEPT GUSTS SHY
OF HIGH WIND CRITERIA.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 1258 PM MST SUN DEC 14 2025
WITH A GENERALLY LOW AMPLITUDE UPPER AIR PATTERN THROUGH THE NEXT
WEEK THERE IS GOOD SYNOPTIC AGREEMENT UPON HOW THE PATTERN UNFOLDS.
BEYOND THE MONDAY NIGHT CLIPPER TO THE NORTH ALONG THE INTERNATIONAL
BORDER WILL BE A STRONGER WAVE COME WEDNESDAY THAT DIVES A BIT
FURTHER SOUTH INTO THE NORTHERN TIER US STATES WITH SUBTLE TIMING
AND STRENGTH DIFFERENCES AMONG GLOBAL ENSEMBLES. THE GEFS AND EURO
ENSEMBLES SHOW GOOD AGREEMENT ON TRACK AND TIMING OF THE WAVE BUT
DISAGREE SLIGHTLY ON THE AMPLITUDE. WHEREAS THE GEFS AND CANADIAN
ENSEMBLES AGREE BETTER ON THE AMPLITUDE OF THE WAVE AS IT PASSES TO
OUR NORTH BUT SHOW SUBTLE TIMING DIFFERENCES WITH THE GEFS BEING
SLIGHTLY SLOWER IN ITS PROGRESSION. NOW WHAT DO THESE DIFFERENCES
MEAN IN TERMS OF IMPACTS FOR THE FORECAST AREA? PROBABLY JUST
DIFFERENCES IN WHEN THE WIND SHUTS OFF AFTER IT BEGINS.
LOOKING AT WED AM THROUGH THUR AM WE SEE 700MB FLOW TICKS UP
OVER 60KTS WITH SOME MEMBERS SHOWING AS HIGH AS 70KTS OR MORE
(LOW CONFIDENCE ON THAT). THIS WILL LIKELY BRING MORE WIDESPREAD
HIGH WINDS TO THE REGION WITH AVAILABLE GUIDANCE SHOWING THIS
TO BE A MORE WIDESPREAD EVENT LIKELY BLEEDING OUTSIDE THE WIND
PRONES AND INTO THE ADJACENT HIGH PLAINS. THIS WEDNESDAY EVENT
LOOKS TO BE A QUICK HITTER AND NOT LONG LASTING THANKFULLY (<24
HOURS). THE PRESSURE GRADIENT THEN LOOKS TO REVERSE FOR THURSDAY
(ONCE WINDS DIE DOWN ON WHICH TIMING IS STILL LOW CONFIDENCE)
SHUTTING OFF THE WIND MACHINE FOR A SHORT TIME BEFORE ANOTHER
SURGE IN WINDS ALOFT BRINGS FLOW EQUAL TO IF NOT SLIGHTLY
STRONGER THAN THE WEDNESDAY EVENT. THIS WOULD BEGIN LATE
THURSDAY LASTING WELL INTO FRIDAY AND POSSIBLY EARLY SATURDAY.
FLOW THEN LOOKS TO TURN MORE ZONAL WITH LESSER CHANCES FOR
SHORTWAVE ACTIVITY TO BRING IMPACTFUL WINDS THE REGION.
ALONG WITH THE WINDS SHOULD COME SOME LIGHT SHOTS OF MOISTURE
WED/THUR AND AGAIN NEXT WEEKEND. THIS WOULD BE MOST IMPACTFUL FOR
THE HIGH TERRAIN (ABOVE 8000FT) WHERE A FEW INCHES OF SNOW WOULD BE
EXPECTED THOUGH CAN'T RULE OUT A FEW HUNDREDTHS OF RAIN OR A DUSTING
OF SNOW IN THE LOW ELEVATIONS. LOOKING AT TEMPS QUICKLY WE ARE QUITE
A BIT ABOVE AVERAGE (37-42F ALONG EAST OF I25) WITH HIGHS LIKELY TO
REACH WELL INTO THE 50S FOR AREAS BELOW 7000FT WEDNESDAY AND THEN
FRIDAY THROUGH THE WEEKEND. THURSDAY WILL BE SLIGHTLY COOLER IN THE
40S BEHIND A COLD FRONT. LOW TO MID 60S EVEN APPEAR PROBABLE
WEDNESDAY AND FRIDAY WITH HIGH TEMPERATURE RECORDS VERY MUCH IN
DANGER FOR MOST LOCATIONS ON FRIDAY.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1035 PM MST SUN DEC 14 2025
QUIET CONDITIONS WITH RELATIVELY LIGHT WINDS AND CLEAR SKIES
CONTINUE THROUGH MONDAY, BEFORE WINDS INCREASE OVER THE SOUTHEAST
WYOMING TERMINALS MONDAY NIGHT.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS EXPECTED WITH LIGHT AND
VARIABLE WINDS OVERNIGHT THROUGH SUNRISE MONDAY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WATCH FROM THIS EVENING THROUGH TUESDAY MORNING FOR
WYZ106.
HIGH WIND WARNING FROM 5 PM THIS AFTERNOON TO 3 PM MST TUESDAY
FOR WYZ110.
HIGH WIND WATCH FROM THIS EVENING THROUGH TUESDAY AFTERNOON
FOR WYZ116-117.
NE...NONE.
SHORT TERM...TJT
LONG TERM...WFOCYS
AVIATION...TJT
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