432
FXUS65 KCYS 121921
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
121 PM MDT SUN JUL 12 2026
KEY MESSAGES
- STRONG RIDGING ALOFT WILL PRODUCE A DRY AND HOT PERIOD FOR
TODAY THROUGH TUESDAY, WITH THE PRIMARY CHALLENGES BEING THE
ABOVE NORMAL HEAT AND FIRE WEATHER CONDITIONS.
- ISOLATED HIGH-BASED THUNDERSTORMS POSSIBLE ON THURSDAY THROUGH
SATURDAY MAINLY NEAR THE MOUNTAINS. ARRIVAL OF THE MONSOON
POSSIBLE LATER IN NEXT WEEKEND.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED AT 121 PM MDT SUN JUL 12 2026
AN UPPER-LEVEL RIDGE WILL DOMINANT THROUGH THE SHORT TERM, KEEPING
SKIES MAINLY CLEAR FOR MOST OF THE FORECAST PERIOD. THIS WILL BRING
GOOD NEWS AND BAD NEWS. LETS START WITH THE GOOD NEWS, EXPECT
PRIMARILY BEAUTIFUL SUNNY AFTERNOONS, WITH AMPLE HEATING AS HIGHS
WILL SOAR INTO THE 90S TO NEAR 100. THE BAD NEWS, THIS HEAT COUPLED
WITH MIN RH VALUES TANKING TO AS LOW AS 5% ACROSS SOUTHEAST WYOMING
AND TO 15% FOR PORTIONS OF THE NEBRASKA PANHANDLE, MAKES THE
ENVIRONMENT PRIME FOR ELEVATED TO CRITICAL FIRE WEATHER
CONDITIONS/CONCERNS AS FUELS CONTINUE TO DRY OUT. THEREFORE, WE HAVE
RED FLAG WARNINGS OUT THROUGH MONDAY AFTERNOON. OUR HI-RES GUIDANCE
SUITE DOESN'T SHOW MUCH IN THE WAY OF ANY POSSIBLE RELIEF DUE TO
SHOWER AND/OR THUNDERSTORM ACTIVITY AS THE OUTPUT SHOWS VIRTUALLY
NOTHING. RINSE AND REPEAT FOR MONDAY, WITH THE UPPER-LEVEL RIDGE
CONTINUING TO DOMINATE, DRY CONDITIONS WILL CONTINUE AND SO WILL THE
RED FLAG WARNINGS. THE AFOREMENTIONED RED FLAG WARNINGS ARE NOT ONLY
OUT DUE TO THE DRY/HOT CONDITIONS, BUT THE WINDS WILL RAMP UP EVER
SO SLIGHTLY WITH GUSTS TO AROUND 25 MPH DUE TO A STRENGTHENING MID-
LEVEL JET, PRIMARILY ALONG AND EAST OF THE I-25 CORRIDOR. WITH
ENOUGH SUBSIDENCE, SOME OF THE STRONGER WINDS WILL MIX DOWN TO THE
SURFACE, CAUSING THOSE HIGHER GUSTS. THE 'WARM' DAYS WILL CONTINUE
AS LOWS ONLY DIP INTO THE 60S/70S AND AS SUCH, THE HEAT ADVISORY WE
ARE UNDER WILL EXTEND INTO THE LONG TERM PERIOD AS HIGHS CONTINUE TO
SOAR INTO AND THROUGH THE 90S, WITH MANY LOCATIONS POSSIBLY HITTING
THE CENTURY MARK.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED AT 121 PM MDT SUN JUL 12 2026
THE WEATHER OVER THE MEDIUM TO LONG RANGE WILL BE DOMINATED BY
THE QUASI-STATIONARY UPPER LEVEL HIGH. THIS UPPER LEVEL HIGH
FORECAST TO REMAIN OVER THE SOUTH-CENTRAL TO CENTRAL UNITED
STATES, INCLUDING THE ROCKY MOUNTAIN REGION. THEREFORE, NOT
EXPECTING CONDITIONS TO CHANGE TOO MUCH THROUGH NEXT WEEK WITH
HOT TEMPERATURES. HOWEVER, RECORD HIGH ACTUALLY APPEAR UNLIKELY
AT THIS TIME SINCE WE ARE HEADING INTO THE WARMEST WEEK OF THE
YEAR, CLIMATOLOGICALLY SPEAKING. FOR EARLY IN THE WEEK, CENTER
OF THE 600DM UPPER LEVEL HIGH WILL BE GENERALLY LOCATED IN THE
CENTRAL ROCKY MOUNTAIN REGION EXTENDING EAST INTO THE CENTRAL
GREAT PLAINS. FORECAST HIGH TEMPERATURES WILL REMAIN IN THE 90S
FOR MOST OF SOUTHEAST WYOMING, INCLUDING THE HIGH VALLEYS WEST
OF THE LARAMIE RANGE. FOR WESTERN NEBRASKA, 95 TO 105 EXPECTED
EACH DAY. SOUTH TO SOUTHEASTERLY WINDS SHOULD CONTINUE EACH DAY
WITH INCREASING CONFIDENCE IN A DECENT BREEZY FOR THE LATE
MORNING HOURS AND THE AFTERNOON. THIS SHOULD RESULT IN SLIGHTLY
COOLER TEMPERATURES ACROSS THE SOUTH FACING RIDGES AND HILLS DUE
TO LOCALIZED UPSLOPE, BUT WE'RE TALKING ABOUT A DIFFERENCE
BETWEEN 91 AN 96 DEGREES, SO THE OVERALL COOLING WILL BE
MINIMAL.
AS WE HEAD INTO LATER IN THE WEEK AND THE WEEKEND, MODELS ARE NOW
SHOWING DIFFERENT SOLUTIONS IN REGARDS TO THE POSITION OF THE UPPER
LEVEL HIGH. THE 12Z ECMWF MAINTAINS THE UPPER LEVEL HIGH OVER
WYOMING, UTAH, AND NORTHERN COLORADO...SIMILAR TO YESTERDAY WHILE
THE GFS AND CANADIAN NOW SHOW THE CENTER OF THE HIGH DRIFTING
SOUTHEAST INTO THE SOUTH CENTRAL PLAINS. THE KEY DIFFERENCE BETWEEN
BOTH SOLUTIONS IN NOT NECESSARILY THE TEMPERATURES, WHICH IS STILL
EXPECTED TO BE VERY WARM TO HOT ACROSS THE FORECAST AREA, BUT
PRECIPITATION CHANCES. GFS AND CANADIAN SHOW THE MONSOON PLUME OVER
COLORADO AND WYOMING BY THE WEEKEND WITH INCREASING THUNDERSTORM
CHANCES. WILL KEEP AN EYE ON THIS TREND OVER THE NEXT FEW DAYS, WITH
A MENTION THUNDERSTORMS ALONG AND WEST OF THE INTERSTATE 25 CORRIDOR
FOR NOW.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1122 AM MDT SUN JUL 12 2026
VFR CONDITIONS WILL PREVAIL ACROSS ALL TERMINALS FOR THE DURATION OF
THIS TAF PERIOD. EXPECT GUSTY WINDS UP TO AROUND 25 KNOTS FOR MOST
OF THE DAYTIME HOURS TODAY, WINDING DOWN SOME DURING THE
EVENING. BY THE TAIL END OF THIS FORECAST PERIOD, WINDS WILL
ONCE AGAIN BEGIN TO RAMP UP WITH GUSTS IN THE 20 TO 30 KNOT
RANGE. SKIES FOR THE THE NEXT 24 HOURS SHOULD REMAIN PRIMARILY
CLEAR.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HEAT ADVISORY UNTIL MIDNIGHT MDT TUESDAY NIGHT FOR WYZ101-102-
107-108-118-119.
RED FLAG WARNING UNTIL 8 PM MDT MONDAY FOR WYZ417>420-423-427-
430>433.
NE...HEAT ADVISORY UNTIL MIDNIGHT MDT TUESDAY NIGHT FOR NEZ002-003-
019>021-054-055-095-096.
RED FLAG WARNING UNTIL 8 PM MDT MONDAY FOR NEZ434.
SHORT TERM...RZ
LONG TERM...TJT
AVIATION...RZ
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