707
FXUS65 KCYS 112308
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
508 PM MDT FRI SEP 11 2026
KEY MESSAGES
- COLD FRONT WILL MOVE THROUGH FRIDAY NIGHT, LEADING TO A COOLER
DAY ON SATURDAY.
- STORM CHANCES INCREASE ON SUNDAY WITH THE POTENTIAL FOR
SEVERE WEATHER.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 223 PM MDT FRI SEP 11 2026
DRY AND WINDY CONDITIONS PERSIST THIS AFTERNOON AHEAD OF AN INCOMING
COLD FRONT. THIS IS FUELING RED FLAG CONDITIONS, MAINLY FOR
AREAS EAST OF THE LARAMIE RANGE. INCREASED MOISTURE ALOFT FROM A
SHORTWAVE THAT MOVED ACROSS THE AREA LAST NIGHT HAS LEAD TO
SOME CUMULUS FIELDS DEVELOPING THIS AFTERNOON. THERE IS SOME
ELEVATED INSTABILITY AS WELL AS SOME LIFT FROM THE APPROACHING
FRONT. THIS COULD LEAD TO A FEW ISOLATED SHOWERS AND STORMS
DEVELOPING LATER THIS AFTERNOON AND EVENING. GIVEN THE DRY
SURFACE, IT IS LIKELY THAT NOT MUCH PRECIPITATION WILL MAKE IT
TO THE GROUND. WIND AND DRY LIGHTNING WILL BE THE MAIN CONCERN
IN ANY STORMS THAT DO DEVELOP TODAY. THE COLD FRONT WILL MOVE
THROUGH LATER THIS EVENING, PUTTING AN END TO THE RED FLAG
CONDITIONS AND SHOWER CHANCES.
A PLEASANT SATURDAY IS EXPECTED FOR MOST OF THE FORECAST AREA.
TEMPERATURES WILL BE MUCH COOLER BEHIND THE FRONT, WITH HIGHS IN THE
UPPER 70S TO LOW 80S. THERE IS ANOTHER CHANCE FOR ISOLATED SHOWERS
AND THUNDERSTORMS FROM ANOTHER WEAK SHORTWAVE, HOWEVER THERE WILL BE
VERY LITTLE INSTABILITY AND SHEAR IN THE POST-FRONTAL
ENVIRONMENT. THEREFORE SEVERE AND LONG LIVED STORMS ARE
UNLIKELY. SUNDAY LOOKS MORE PROMISING FOR STORMS AND SEVERE
WEATHER. A STRONGER TROUGH WILL BEGIN TO PUSH INTO WYOMING,
RAISING TEMPERATURES AND ADVECTING MOISTURE INTO THE CWA.
INSTABILITY WILL BE MUCH HIGHER, WITH CAPE VALUES RISING WELL
ABOVE 1500 J/KG. AMPLE SHEAR AND EVEN HIGH SRH VALUES IN THE
NEBRASKA PANHANDLE MAKE SEVERE WEATHER SEEMINGLY LIKELY ON
SUNDAY. HOWEVER, MODEL SOUNDINGS DO SHOW A STRONG CAPPING
INVERSION FOR MUCH OF THE DAY WHICH COULD AFFECT SEVERE WEATHER
POTENTIAL. WILL CONTINUE TO MONITOR THE STORM THREAT FOR SUNDAY
OVER THE NEXT FEW MODEL CYCLES.
LONG TERM /MONDAY 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 /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 508 PM MDT FRI SEP 11 2026
PRIMARILY VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD, AS A
COLD FRONT MOVES THROUGH THIS EVENING, WHICH WILL SHIFT THE WINDS
FROM MORE WESTERLY EAST OF THE LARAMIE RANGE, TO NE BEHIND THE
FRONT. THERE IS A SLIGHT CHANCE (~20%) OF SOME LOW CLOUDS DEVELOPING
IN THE COOL, CALMER, AND MOIST POST-FRONTAL UPSLOPE FLOW REGIME
AFTER 09Z, MAINLY FOR KCYS AND THE NEBRASKA TERMINALS, HOWEVER CIGS
ARE NOT EXPECTED TO BE LOW ENOUGH FOR MVFR AND CONFIDENCE IS LOW.
WINDS WILL GRADUALLY SHIFT TO MORE SE EAST OF THE I-25 CORRIDOR
DURING THE AFTERNOON HOURS, WITH PEAK GUSTS OF 25-30 KNOTS OUT OF
THE WEST AT KLAR AND KRWL.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR WYZ429>433.
NE...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR NEZ434>437.
SHORT TERM...SF
LONG TERM...ML
AVIATION...NB
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