859
FXUS65 KCYS 081722
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1122 AM MDT TUE SEP 8 2026
KEY MESSAGES
- CHANCES FOR LIGHT AND BRIEF SHOWERS WITH TEMPORARY STRONG WIND
GUSTS POSSIBLE THIS EVENING.
- A TEMPORARY DRYING TREND BEGINS TUESDAY AND POSSIBLY
CONTINUING THROUGH THE END OF THE WEEK.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED AT 255 AM MDT TUE SEP 8 2026
SOME WEAK SHOWERS PERSIST FOLLOWING A SURFACE COLD FRONT THAT IS
EXPECTED TO STALL ALONG THE WY/CO BORDER. THE UPPER LEVEL LOW IS
DIRECTLY NORTH OF OUR FORECAST AREA ALONG THE CANADIAN BORDER EVER
SO SLOWLY PUSHING EAST. A 700MB COLD FRONT WILL PUSH THROUGH
TOMORROW DROPPING 700MB TEMPERATURES FROM 12/14C DOWN TO AROUND 6/7C
AROUND PEAK HEATING TO THE EVENING TIME. DUE TO THE KIND OF LATE
ARRIVAL SURFACE TEMPERATURES WILL ONLY BE 4 DEGREES COOLER FROM THE
PREVIOUS DAY. THIS COLD FRONT MAY CREATE SOME LIGHT SHOWERS IN THE
SOUTHERN COUNTIES WHERE LOW LEVEL MOISTURE GETS TRAPPED UNDERNEATH
OUR EXPANDING RIDGE. HI-RES MODELS DEPICT A SWATH OF 200-500 JOULES
OF CAPE IN SOME AREAS BUT DEPENDING HOW FAST THE WINDS SWITCH FROM
SOUTHWEST TO WEST AS THE UPPER LEVEL LOW PULLS FURTHER AWAY FROM US
SOME CLOUDS MAY FORM AND MAY NOT PRODUCE ANY PRECIPITATION. INSTEAD
WE WILL GET GUSTY OUTFLOWS AND MICROBURST IN THE EVENING INTO THE
OVERNIGHT HOURS. HI-RES GUIDANCE CLEARS THE SHOWERS OUT BY 06Z OR
MIDNIGHT. WEDNESDAY, WE WILL CONTINUE TO BE PREDOMINANTLY IN OUR
WESTERLY DOWNSLOPING FLOW. THE DOWNSLOPING FLOW WILL KEEP THE COLDER
AIRMASS ABOVE US FROM DROPPING THE TEMPERATURE BELOW 70 DEGREES. THE
DAILY HIGH TEMPERATURE IS EXPECTED TO BE MOSTLY IN THE 70'S WITH THE
NEBRASKA PANHANDLE IN THE LOW 80'S. OVERNIGHT TEMPERATURES WILL BE
A BIT COOLER WITH TEMPERATURES IN THE 40'S AND 50'S.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED AT 255 AM MDT TUE SEP 8 2026
THE RIDGE CONTINUES TO ELONGATE THROUGH THE MIDDLE OF THE WORK
WEEK, PLACING OUR AREA IN PRIMARILY ZONAL FLOW ALOFT AND
THEREFORE MOSTLY DRY CONDITIONS. A WARMING TREND IS EXPECTED ON
THURSDAY AND FRIDAY AS A SECONDARY RIDGE BEGINS TO BUILD ACROSS
THE DESERT SOUTHWEST. WILL HAVE TO MONITOR FIRE WEATHER
CONDITIONS ON BOTH OF THESE DAYS AS ENSEMBLE GUIDANCE IS HINTING
AT GUSTY WESTERLY WINDS OF 25-35 KNOTS COMBINED WITH DAYTIME RH
VALUES DIPPING TO 15- 20%.
HEADING INTO THE WEEKEND, WE START TO BRING BACK THE FETCH OF
MONSOONAL MOISTURE AHEAD OF A SHORTWAVE TROUGH DIGGING ACROSS THE
PACIFIC NORTHWEST, PLACING SOUTHEASTERN WYOMING AND WESTERN NEBRASKA
IN WSW FLOW ALOFT. WITH THE LACK OF SIGNAL FOR ANY SUBSTANTIAL
FORCING FROM LONG-RANGE ENSEMBLE GUIDANCE, NO WIDESPREAD (AND
BENEFICIAL) PRECIPITATION IS EXPECTED. HOWEVER CAN EXPECT A SLIGHT
COOLING TREND WITH THIS NEXT PUSH OF MOISTURE AND THE USUAL DIURNAL
PATTERN OF SCATTERED AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1122 AM MDT TUE SEP 8 2026
A FEW ISOLATED SHOWERS, POSSIBLY A RUMBLE OF THUNDER, MAY COME IN
THE VC OF KCYS, KBFF, AND KSNY THIS AFTERNOON. THE MAIN AVIATION
HAZARD WITH THIS ACTIVITY WILL BE THE GUSTY AND ERRATIC WINDS THAT
ACCOMPANY ANY SHOWER, WITH SPEEDS UP TO 20 KNOTS. OTHERWISE, FOR THE
REMAINDER OF THE TERMINALS, VFR CONDITIONS WILL PREVAIL FOR THE
DURATION OF THIS TAF PERIOD. WINDS, IN GENERAL, SHOULD REMAIN 10
KNOTS OF LESS ACROSS ALL SITES EXCEPT KCYS AND KLAR WHERE
BREEZIER CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON
HOURS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ417>423-
427-428.
NE...NONE.
SHORT TERM...MM
LONG TERM...NB
AVIATION...RZ
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