346
FXUS65 KCYS 121750
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1150 AM MDT SAT SEP 12 2026
KEY MESSAGES
- COOLER TEMPERATURES ON SATURDAY ALONGSIDE SOME ISOLATED SHOWER
OR STORM CHANCES BUT REMAINING WEAK OVERALL.
- TEMPERATURES WARM ON SUNDAY AND MONDAY WITH INCREASING
PRECIPITATION CHANCES, THOUGH MONDAY MAY SEE THE RETURN OF
CRITICAL FIRE WEATHER CONDITIONS.
- MUCH COOLER ON TUESDAY WITH TEMPERATURES A FEW DEGREES WARMER
THROUGH THE END OF NEXT WEEK AND DAILY CHANCES OF SHOWERS AND
THUNDERSTORMS.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED AT 145 AM MDT SAT SEP 12 2026
POST-FRONTAL ENVIRONMENT WILL LEAD TO COOLER TEMPERATURES ON
SATURDAY ALONG WITH ANOTHER CHANCE OF SCATTERED SHOWERS AND
THUNDERSTORMS, WITH TEMPERATURES INCREASING ON SUNDAY AND MONDAY
AND FURTHER SHOWER AND THUNDERSTORM CHANCES ALONGSIDE THE
RETURN OF FIRE WEATHER CONCERNS BY MONDAY AS THE SURFACE DRIES
OUT ONCE AGAIN. FOR TODAY, HIGHS WILL SIT COMFORTABLY IN THE
70'S TO LOW 80'S FOR THE DAY. RAWLINS WILL ACTUALLY BE ONE OF
THE WARMEST LOCATIONS FOR ONCE AS THE FRONT SHOULD BE SNAGGED UP
ON THE HIGH TERRAIN OR LIFTING JUST NORTHEAST OF THE AREA. A
WEAK SHORTWAVE SHOULD ALSO HELP TO FUEL ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS FOR THE DAY, BUT WITH SEVERE PARAMETERS
LACKING NOT EXPECTING MUCH MORE THAN GENERIC PRECIPITATION WITH
LITTLE IN THE WAY OF NOTEWORTHY ACTIVITY. FINALLY, GUSTY WINDS
EXPECTED THANKS TO THE ENHANCED SURFACE PRESSURE GRADIENT, WITH
WESTERLY WINDS ON THE WEST SIDE OF THE FRONT, AND SOUTHERLY TO
SOUTHEASTERLIES EAST OF THE FRONT.
SUNDAY WAS LOOKING BETTER FOR STRONGER TO SEVERE THUNDERSTORMS,
BUT LATEST MODEL RUNS INCLUDING HIGH RESOLUTION GUIDANCE ARE
SHOWING A COOLER AND MORE STABLE LAYER THAT MAY INHIBIT STRONGER
DEVELOPMENT. THE POTENTIAL IS THERE WITH SOME MODERATE
INSTABILITY AND DECENT WIND SHEAR, BUT EVEN OUR PARTNERS IN THE
SPC HAVE REMOVED THE MARGINAL SEVERE RISK WE WERE UNDER.
OTHERWISE, THE SURFACE BOUNDARY SHOULD SLOWLY LIFT BACK UP AS A
WARM FRONT AS A TRANSIENT RIDGE MOVES ACROSS, WITH WIDESPREAD
TEMPERATURES BACK UP INTO THE UPPER 70'S TO UPPER 80'S FOR THE
DAY. SURFACE PRESSURE GRADIENTS WILL ONCE AGAIN PROMOTE BREEZY
TO GUSTY WINDS, ONCE AGAIN SPLIT BY THE BOUNDARY AS
SOUTHWESTERLIES ARE EXPECTED TO THE WEST OF THE LARAMIE RANGE
AND SOUTHEASTERLIES ARE EXPECTED TO THE EAST.
MONDAY A DEEP UPPER LEVEL PACIFIC LOW WILL BE MOVING ACROSS THE
US/CANADA BORDER WITH AN ATTENDANT TROUGH PASSING THROUGH OUR
FORECAST AREA. AT THE SURFACE, ANOTHER COLD FRONT IS EXPECTED TO
DROP DOWN AND MOVE ACROSS WITH ANOTHER ROUND OF PRECIPITATION
POSSIBLE BUT MOSTLY RELEGATED TO THE I-80 CORRIDOR AND
SOUTHWARD. SEVERE INGREDIENTS ARE ALSO LACKING, SO EXPECT
GENERAL SHOWERS AND THUNDERSTORMS. TEMPERATURES FOR THE DAY ON
TRACK TO BE QUITE WARM, AT LEAST EAST OF THE LARAMIE RANGE WITH
HIGHS IN THE UPPER 70'S TO NEAR 90 DEGREES FOR GOSHEN COUNTY AND
THE SOUTHERN HALF OF THE NEBRASKA PANHANDLE. WEST OF THE LARAMIE
RANGE MEANWHILE, THE COOLER AIRMASS SHOULD MOVE ACROSS EARLY
ENOUGH THAT HIGHS WILL BE LIMITED TO THE LOW TO MID 70'S FOR THE
DAY. THIS SHOULD ALSO BE THE WINDIEST DAY OF THE FORECAST
PERIOD, AND IN-HOUSE GUIDANCE INDICATES A 30-40% PROBABILITY OF
HIGH WIND WARNINGS BEING NEEDED (GUSTS 58+ MPH). CURRENTLY
EXPECTING WIDESPREAD GUSTS SHOULD REMAIN JUST UNDER THE NEED FOR
PRODUCTS, BUT AS ALWAYS WYOMING CAN SURPRISE AND WILL NEED TO
KEEP AN EYE ON HOW THIS ENVIRONMENT DEVELOPS. FINALLY THE
SURFACE WILL BE QUITE DRY FOR THE DAY WITH RELATIVE HUMIDITY
VALUES DROPPING INTO THE 10-20% RANGE. IF THIS DOES HOLD
TOGETHER, A NEW BATCH OF RED FLAG WARNINGS WILL BE NEEDED,
PRIMARILY FOR SOUTHEAST WYOMING AND LOOKING TO REMAIN JUST
OUTSIDE OF LARAMIE COUNTY.
LONG TERM /TUESDAY THROUGH FRIDAY/
ISSUED AT 223 PM MDT FRI SEP 11 2026
SUNDAY NIGHT INTO MONDAY MORNING SHOWS A COLD
FRONT PASSING OVER THE CWA. AFTER THIS FRONT MOVES OUT, A RIDGE
STARTS TO BUILD, BRINGING COOLER TEMPERATURES AND DRYER AIR. SOME
STORM AND SHOWER ACTIVITY IS POSSIBLE TUESDAY EVENING WITH RETURN
FLOW. A SHORTWAVE PASSES THROUGH ON THURSDAY EVENING, ALLOWING THE
RIDGE TO CONTINUE TO BUILD. ON FRIDAY THE RIDGE GETS PUSHED OUT BY A
TROUGH FORMING OVER THE REGION. SOME MODELS ARE SHOWING
PRECIPITATION POTENTIAL FRIDAY AFTERNOON, BUT MORE TO COME ON THAT
AS WE GET CLOSER. 700MB TEMPERATURES ARE IN THE 10-15C RANGE IN THIS
LONG TERM PERIOD. TEMPERATURES START TO COOL OFF AND FEEL MORE LIKE
FALL AS THE WEEK PROGRESSES.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1151 AM MDT SAT SEP 12 2026
SOME SHOWERS POSSIBLY WEAK THUNDERSTORMS WILL BE SKIRTING
THROUGH KLAR AND KCYS THIS AFTERNOON. MOSTLY VIRGA ANTICIPATED
BUT THERE MAY BE A BRIEF SHOWER OR TWO THIS AFTERNOON. BY THE
EVENING THESE SHOWERS ARE EXPECTED TO MAKE IT TO KSNY AND
POSSIBLY AS FAR NORTH AS KBFF. WINDS LOOK TYPICAL FALL SEASON
THROUGH THE DAY WITH SOME BRIEF STRONG GUSTS POSSIBLE
UNDERNEATH THESE SHOWERS/ WEAK THUNDERSTORMS. WIND GUSTS MAY
LAST THROUGH THE NIGHT FOR KCYS AND THE NEBRASKA TERMINALS AS AN
UPPER LEVEL LOW STARTS TO PUSH INTO THE INTERMOUNTAIN WEST
TIGHTENING OUR PRESSURE GRADIENT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...CG
LONG TERM...ML
AVIATION...MM
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