889
FXUS65 KCYS 110455
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1055 PM MDT SAT OCT 10 2026
KEY MESSAGES
- ABOVE AVERAGE TEMPERATURES AND CHANCES FOR GUSTY SHOWERS AND
SOME ISOLATED STORMS THROUGH SUNDAY.
- A PATTERN CHANGE WILL BRING A GRADUAL COOL DOWN AND INCREASED
CHANCES FOR PRECIPITATION NEXT WEEK.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 330 PM MDT SAT OCT 10 2026
AREAS OF SHOWERS AND AN ISOLATED STORM OR TWO ARE MAKING THEIR
WAY ACROSS THE REGION THIS AFTERNOON. WHILE ALL DETERMINISTIC
GUIDANCE ABSOLUTELY FAILED ON WHERE THIS PRECIPITATION IS
OCCURRING AND HOW FAR EAST IT'S SPREADING, HIGH RESOLUTION
GUIDANCE HAS BEEN MUCH MORE HELPFUL IN DETERMINING WHERE
CONVECTION WILL OCCUR. MADE LARGE AND SWEEPING CHANGES TO
PRECIPITATION, SPREADING IT ACROSS ALL OF SOUTHEAST WYOMING AND
THROUGH THE UPPER 2/3'S OF THE NEBRASKA PANHANDLE TO ACCOUNT FOR
THIS ACTIVITY. LOOKING AT MESOANALYSIS FOR THUNDERSTORM
POTENTIAL, MOST FAVORABLE INSTABILITY LIES JUST TO OUR SOUTH AND
WEST, WHICH IS ALLOWING A STORM OR TWO TO LIFT UP INTO THE
REGION, MAINLY CARBON COUNTY, BEFORE WEAKENING INTO SHOWER
ACTIVITY AS IT CONTINUES TO PROGRESS. LIKELY EXPECTING THIS TO
CONTINUE, BUT NOT GOING TO RULE OUT AN ISOLATED LIGHTNING STRIKE
OR TWO IN ANY HEAVIER SHOWERS, AND DEFINITELY EXPECTING GUSTY
WINDS AS HAS BEEN SEEN THIS AFTERNOON WITH MANY OF THE SHOWERS
THANKS TO FAVORABLE SOUNDING PROFILES.
OVERNIGHT INTO TOMORROW, SHOWERS AND STORMS SHOULD RECEDE ACROSS
THE REGION, THOUGH OCCASIONAL LINGERING PRECIPITATION FOR CARBON
COUNTY EXPECTED THROUGH THE NIGHT. LOOKING AT A LARGELY SIMILAR
PRECIPITATION SPREAD FOR TOMORROW THOUGH SHOWER CHANCES SHOULD
BE A BIT HIGHER ACROSS THE REGION OVERALL. THIS WILL BE THANKS
TO A LARGER INFLUX OF PWATS, AS VALUES 200% OF NORMAL ARE
EXPECTED (0.8-1.0 INCH ON AVERAGE). SIMILAR TO TODAY, CAPE
VALUES WILL BE STRONGEST JUST TO OUR SOUTHWEST, BUT A FEW VALUES
IN EXCESS OF 500 J/KG MAY MOVE INTO CARBON COUNTY. WE MAY SEE A
STRONGER STORM OR TWO POSSIBLE, EVEN BORDERING INTO MARGINALLY
SEVERE, BUT OTHERWISE FORECAST PROFILES ARE STILL FAVORING
GUSTY SHOWERS WITH ISOLATED LIGHTNING. LOOKING AT THE REMAINDER
OF THE FORECAST, THE OVERSPREADING CLOUD COVER AND COOL FRONT
MOVING INTO THE REGION WILL HELP PROMOTE TEMPERATURES A FEW
DEGREES COOLER THAN TODAY. WHILE STILL NOTABLY WARMER THAN
AVERAGE, WE SHOULD SEE MOST LOCATIONS FINALLY DROPPING BELOW 80
DEGREES FOR THE DAY, THOUGH THE SOUTHERN PANHANDLE AND PERHAPS
TORRINGTON MAY STILL PEAK AT JUST AROUND 80 FOR THE DAY.
WHILE WINDS WILL BE GENERALLY BREEZY UNDER AN ENHANCED PRESSURE
GRADIENT, A JET STREAK WILL PUSH ACROSS DURING THE NIGHTTIME
HOURS INTO MONDAY, FUELING SOME STRONGER WINDS FOR OUR WESTERN
ZONES. THESE COULD BE BORDERLINE HIGH WIND WARNING LEVEL, AND IN
HOUSE GUIDANCE FAVORS A 25-30% CHANCE OF WINDS EXCEEDING 58 MPH,
BUT OVERALL CONFIDENCE IS STILL TOO LOW TO CONSIDER EVEN A WATCH
AT THIS TIME. THAT BEING SAID MUCH LIKE TODAY, DON'T BE
SURPRISED IF WE DO ACHIEVE SEVERAL GUSTS IN THE 50-60 MPH RANGE
BETWEEN GUSTY SHOWER ACTIVITY AND THE AFOREMENTIONED ENHANCED
WINDS. OVERALL IT WILL BE AN ACTIVE WEEKEND, AND AT LEAST THE
BEGINNING OF THE END TO OCTOBER FEELING MORE LIKE SUMMER.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 330 PM MDT SAT OCT 10 2026
THE EXCEPTIONALLY WARM WEATHER PATTERN FOR THIS TIME OF YEAR WILL
FINALLY BREAK DOWN THIS WEEK, AS THE WEATHER WILL ACTUALLY FEEL LIKE
OCTOBER BY THE MIDDLE OF THE WEEK. ONE MORE DAY OF UNUSUAL WARMTH IS
ANTICIPATED FOR MONDAY. WHILE THE SPRAWLING UPPER LEVEL LOW WILL
REMAIN TO OUR WEST, THE SUBTLE SHORT-WAVE PROVIDING FORCING FOR THE
EARLIER SHOWER ACTIVITY WILL LIFT TO OUR NORTHEAST. SYNOPTIC DESCENT
WILL PUSH IN BEHIND ALONG WITH A DRIER AIRMASS DROPPING PRECIPITABLE
WATER CLOSER TO SEASONAL AVERAGES. WHILE SOME SHOWER ACTIVITY DRIVEN
BY SSW UPSLOPE FLOW WILL LIKELY PERSIST IN CARBON COUNTY, EXPECT A
LULL IN THE SHOWER CHANCES FOR MUCH OF THE AREA MONDAY MORNING. HIGH
TEMPERATURES WILL STILL BE AROUND 10F ABOVE SEASONAL AVERAGES. WE
WILL STILL HAVE ENOUGH MOISTURE LINGERING TO SUPPORT HIGH-BASED
SHOWERS IN THE LATE AFTERNOON AND EVENING, BUT APPRECIABLE RAINFALL
IS UNLIKELY.
THE WARM PATTERN WILL FINALLY BREAK ON TUESDAY, WITH NEARLY ALL
ENSEMBLE MEMBERS IN AGREEMENT. A NORTHERN BRANCH SHORTWAVE TROUGH
PASSING WELL TO OUR NORTH APART FROM THE STALLED UPPER LEVEL LOW TO
OUR WEST WILL SUPPORT A MODEST SURFACE HIGH PRESSURE CENTER OVER THE
NORTHERN PLAINS. THIS FEATURE WILL PUSH A COOL FRONT THROUGH THE
AREA MONDAY NIGHT, LEADING TO A COOLER DAY TUESDAY. THE FRONTAL
BOUNDARY IS EXPECTED TO STALL AGAINST THE LARAMIE RANGE ONCE AGAIN.
SO, WHILE AREAS ALONG AND EAST OF I-25 SHOULD BE A GOOD 10F OR EVEN
15F COOLER THAN MONDAY, LARAMIE AND RAWLINS MAY ONLY DROP A FEW
DEGREES. AS THE FRONT PUSHES IN OVERNIGHT, MODELS ARE MORE
CONSISTENTLY SHOWING ISENTROPIC LIFT ON THE EAST SIDE OF THE
APPROACHING UPPER LEVEL LOW DEVELOPING OVER MUCH OF THE AREA. THUS,
EXPECT TO SEE SHOWER COVERAGE INCREASING MONDAY NIGHT INTO EARLY
TUESDAY MORNING. STILL, RAINFALL RATES AND AMOUNTS LOOK LIGHT DURING
THIS WINDOW. LOOK FOR ANOTHER LULL DURING THE DAYTIME HOURS ON
TUESDAY AS THE FORCING WEAKENS TEMPORARILY. A FEW SHOWERS WILL
PROBABLY LINGER ACROSS THE AREA, BUT WITH MUCH MORE LIMITED
COVERAGE. MODELS ARE IN GOOD AGREEMENT NOW SHOWING VERY STRONG
ISENTROPIC LIFT AND POSITIVE THETA-E ADVECTION KICKING UP AGAIN
TUESDAY EVENING AND LASTING INTO WEDNESDAY. THIS LOOKS LIKE THE BEST
WINDOW FOR BENEFICIAL RAINFALL FOR MOST OF OUR AREA DUE TO THE MORE
POTENT FORCING. SNOW LEVELS WILL START AROUND 10 KFT AND DROP TO
8500 OR EVEN 8000 FT INTO WEDNESDAY MORNING. THUS, SNOW IS LIKELY IN
THE SNOWY AND SIERRA MADRE, AND POSSIBLE AS LOW AS THE I-80 SUMMIT
AND ARLINGTON/ELK MOUNTAIN AREAS. HOWEVER, RELATIVELY FEW ENSEMBLES
(10% OR SO) HAVE THE TEMPERATURES COLD ENOUGH TO SUPPORT SNOW LEVELS
DROPPING TO POPULATED AREAS OF SOUTHEAST WYOMING, AT LEAST DURING
THE TUESDAY NIGHT TO THURSDAY MORNING PERIOD.
ENSEMBLE AGREEMENT FALLS APART COMPLETELY WEDNESDAY NIGHT AND
BEYOND. MODELS HAVE DIVERGED INTO TWO DISTINCT CAMPS WITH STARKLY
DIFFERENT OUTCOMES FOR OUR AREA. THE PRIMARY PIECE OF THE PUZZLE
DRIVING THIS UNCERTAINTY IS THE TRACK OF A POWERFUL AND COLD UPPER
LEVEL LOW DROPPING OUT OF CANADA MID TO LATE WEEK. IN ONE CAMP, THE
WESTERN RIDGE RECOVERS QUICKLY ENOUGH TO DEFLECT THIS TROUGH TO THE
EAST, PUSHING IT INTO THE GREAT LAKES AREA. IN THIS CASE, THE UPPER
LEVEL CLOSED LOW WOULD GET ABANDONED UNDERNEATH THE RE-AMPLIFYING
RIDGE, KEEPING UNSETTLED WEATHER BUT GENERALLY LIGHT WINDS AND
WARMER TEMPERATURES, IN PLACE OVER OUR AREA. IN THE OTHER SCENARIO,
THE UPPER LEVEL LOW PLUNGES INTO THE US MUCH FURTHER WEST, POSSIBLY
AS FAR AS DOWN THE EASTERN FRONT OF THE ROCKIES. THIS WOULD FIRST
ALLOW THE THE CLOSED LOW TO EJECT OFF TO THE NORTHEAST, AND THEN
BRING A POTENT SURGE OF COLD AIR TO THE AREA ON FRIDAY. IN THIS
SCENARIO, THERE WOULD BE POTENTIAL FOR HIGH WINDS ACROSS THE PLAINS
ON THURSDAY, FOLLOWED BY WIDESPREAD FREEZING TEMPERATURES FRIDAY.
ABOUT 20% OF TOTAL ENSEMBLE MEMBERS PUSH THE TROUGH FAR ENOUGH WEST
TO BRING ANOTHER ROUND OF UPSLOPE PRECIPITATION TO THE AREA, WHICH
WOULD HAVE MUCH LOWER SNOW LEVELS (LIKELY SNOW DOWN TO AT LEAST 5000
FT, IF THIS SCENARIO WERE TO PLAY OUT). ENSEMBLES ARE SPLIT NEARLY
EXACTLY 50/50 RIGHT NOW, SO THERE IS NOT MUCH INSIGHT INTO WHICH IS
FAVORED AT THIS TIME. THE OFFICIAL FORECAST STRADDLES THE MIDDLE
BETWEEN THEM AT THIS TIME.
WHILE THIS WEEK WILL PROVIDE IMPROVED CHANCES FOR BENEFICIAL
PRECIPITATION FOR MUCH OF THE AREA, EXACT AMOUNTS ARE STILL QUITE
UNCERTAIN. WHILE ENSEMBLE MEANS ARE FAIRLY HIGH, IT IS WORTH
MENTIONING THAT THERE ARE A SMALL NUMBER (10 TO 15%) OF EXTREME HIGH
END OUTLIER SCENARIOS THAT MIGHT BE SKEWING THE AVERAGE. ENSEMBLE
MEDIAN QPF GENERALLY RANGES AROUND 0.5 TO 0.75" IN SOUTHEAST
WYOMING, AND 0.3 TO 0.6" IN WESTERN NEBRASKA. THE NBM DISTRIBUTION
APPEARS SOMEWHAT INEXPLICABLY HIGHER THAN THE ECMWF ENSEMBLE MEDIAN
AND EVEN THE AGGRESSIVE GEFS MEDIAN. IN ADDITION, AI ENSEMBLES ARE
CONSIDERABLY DRIER THAN THE CONVENTIONAL NWP SYSTEMS. THE ECMWF AIFS
MEDIAN IS AROUND 0.25 TO 0.5" FOR THE HIGH PLAINS, WHILE THE GEFS AI
IS EVEN LOWER, AROUND 0.1" TO 0.4". THIS WILL BE ANOTHER INTERESTING
TEST ON CONVENTIONAL NWP VERSUS NEWER AI ENSEMBLE SYSTEMS AS WE SEE
HOW THIS PLAYS OUT.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 1052 PM MDT SAT OCT 10 2026
MOSTLY LIGHT WINDS EXPECTED OVERNIGHT AT ALL TERMINALS EXCEPT
KRWL, WHERE GUSTY WINDS CONTINUE WITH SHOWERS MOVING NEAR THE
AREA. KRWL IS NOT EXPECTING SIGNIFICANT DECREASES IN WINDS FOR
THE 06Z TAF PERIOD, SO BREEZY CONDITIONS WILL CONTINUE. ALL
OTHER TERMINALS WILL SEE WINDS SWITCHING TO THE NORTH LATE
MORNING INTO THE EARLY AFTERNOON HOURS AS A WEAK FRONT MOVES
THROUGH THE REGION. OCCASIONAL GUSTY WINDS WILL BE POSSIBLE WITH
THE FRONTAL PASSAGE. CLOUDS START TO CLEAR INTO THE AFTERNOON
AND EVENING HOURS BEHIND THE FRONT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...CG
LONG TERM...MN
AVIATION...AM
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