551
FXUS65 KCYS 111149
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
549 AM MDT THU SEP 11 2025
KEY MESSAGES
- DAILY CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS CONTINUE
THROUGH FRIDAY WITH GUSTY WINDS, DOWNPOURS, AND ISOLATED HAIL
POSSIBLE.
- A COLD FRONT WILL IMPACT THE AREA LATER THIS WEEK BRINGING
COOLER TEMPERATURES THROUGH THE WEEKEND.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 333 AM MDT THU SEP 11 2025
CURRENT RADAR SHOWS PERSISTENT SHOWERS AND STORMS ACROSS THE
CWA. MODEL SOUNDINGS STILL SHOW A BIT OF INSTABILITY ACROSS THE
AREA, CONTRIBUTING TO THE ONGOING LATE NIGHT/EARLY MORNING
CONVECTION. SHOWERS WILL LIKELY CONTINUE THROUGH THE MORNING
HOURS PER HI-RES GUIDANCE. MOIST SOUTH TO SOUTHEAST FLOW ACROSS
THE AREA THIS MORNING WILL ALSO LEAD TO THE DEVELOPMENT OF LOW
STRATUS AND POTENTIALLY SOME PATCHY FOG IN THE NEBRASKA
PANHANDLE AS WELL AS LARAMIE COUNTY AND THE NORTH PLATTE RIVER
VALLEY. ANY FOG THAT DEVELOPS WILL LIKELY DISSIPATE BY MID-
MORNING AS WINDS INCREASE. LOW STATUS COULD LINGER INTO THE
EARLY AFTERNOON AS LOW-LEVELS REMAIN MOIST.
HEADING INTO THE AFTERNOON, THE DEEP UPPER-LEVEL TROUGH OVER THE
GREAT BASIN WILL SEND WAVES OF VORTICITY MAXES INTO THE CWA. THESE
VORT MAXES, AS WELL AS SOME JET ENERGY WILL HELP SPARK THUNDERSTORM
DEVELOPMENT ACROSS MOST OF THE CWA. HI-RES GUIDANCE SHOWS MORE
WIDESPREAD COVERAGE OF SHOWERS AND STORMS COMPARED TO WEDNESDAY.
CANNOT RULE OUT A FEW STRONG TO MARGINALLY SEVERE STORMS, ESPECIALLY
IN THE NEBRASKA PANHANDLE. GFS MODEL SOUNDINGS SHOW POCKETS OF 2000
J/KG OF MUCAPE ACROSS THE PANHANDLE. THIS COULD LEAD TO A FEW STORMS
CONTAINING SEVERE HAIL. ACROSS BOTH NEBRASKA AND WYOMING, DCAPE
VALUES ARE AT 1000 J/KG AND HIGHER, SO SEVERE WIND GUSTS ALSO CANNOT
BE RULED OUT IN STORMS. ASIDE FROM THE SEVERE POTENTIAL, PWATS WILL
BE ELEVATED SO HEAVY RAIN CAN BE EXPECTED IN STORMS. ONCE AGAIN,
STORMS WILL LINGER INTO THE OVERNIGHT HOURS AS THE TROUGH SLOWLY
MOVES EASTWARD.
BY FRIDAY, THE TROUGH WILL BEGIN TO MOVE INTO WYOMING, LEADING TO
YET ANOTHER ROUND OF PRECIPITATION ACROSS THE AREA. THE AFTERNOON
WILL FEATURE SCATTERED SHOWERS AND STORMS, WHICH WILL TURN MORE
STRATIFORM DURING THE EVENING HOURS. COVERAGE OF STORMS WILL ONCE
AGAIN BE WIDESPREAD ACROSS MOST OF THE CWA. A QUICK LOOK AT MODEL
SOUNDINGS SUGGESTS STORMS WILL BE SUB-SEVERE AS INSTABILITY LOOKS
RELATIVELY WEAK.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
ISSUED AT 140 PM MDT WED SEP 10 2025
FRIDAY IS EXPECTED TO BE THE WARMEST DAY OF THE LONG TERM AS
HIGH PRESSURE RIDGING BEGINS TO SHIFT EASTWARDS, BUT THE REGION
REMAINS UNDER A WARM SOUTHWESTERLY FLOW AS A DEEP TROUGH BEGINS
APPROACHING OUR AREA. THIS SYSTEM WILL MOVE ACROSS AND CONTINUE
EASTWARDS THROUGH THE WEEKEND. THIS SHOULD ALLOW FOR TWO FAIRLY
SIMILAR DAYS OVER THE WEEKEND, WITH COOLER TEMPERATURES AND
HIGHS IN THE 70'S MOSTLY, THOUGH SOME HIGH 60'S MAY BE POSSIBLE
FURTHER WEST, WHILE TO THE EAST IN THE NEBRASKA PANHANDLE HIGHS
WILL PEAK IN THE LOW 80'S. A TRANSITORY RIDGE THEN HELPS TO
WARM US BACK UP FOR THE FIRST COUPLE OF DAYS NEXT WEEK, WITH
70'S TO 80'S RETURNING TO THE CWA BEFORE ANOTHER UPPER LEVEL LOW
IS EXPECTED TO BRING A RETURN TO COOLER CONDITIONS BY THE
MIDDLE OF NEXT WEEK. WITH THIS INITIAL SYSTEM WE SHOULD SEE
PRECIPITATION TO END THE WEEK AND BEGIN THE WEEKEND, WITH
WIDESPREAD RAIN AND THUNDER THROUGH SATURDAY. MOISTURE WON'T BE
EXTREMELY HIGH, WITH PWAT VALUES ONLY AROUND 125-150% OF NORMAL
ACCORDING TO ENSEMBLES, WHICH IS STILL UNDER AN INCH FOR OUR
CWA. THIS LEADS TO QPF OF AROUND OR UNDER A QUARTER OF AN INCH
FOR FRIDAY AND SATURDAY, HARDLY A WIDESPREAD SOAKER AS WE SEE
THE BEST FETCH OF MOISTURE KEPT OFF TO OUR NORTHEAST. STILL
ANYTHING HELPS, AND A FEW LOCATIONS MAY SEE LOCALLY HEAVIER
AMOUNTS DEPENDING ON THE STRENGTH OF THUNDERSTORMS IN THE
REGION. SUNDAY AND MONDAY ARE EXPECTED TO BE DRY WITH THE
TRANSIENT RIDGE MOVING IN, BUT WE'LL SEE MOISTURE RETURN ON
TUESDAY ALONGSIDE PRECIPITATION CHANCES ONCE AGAIN. OVERALL
THERE IS ONLY MODERATE CONFIDENCE (50%) IN THE FORECAST, WITH
ENSEMBLE CLUSTERS FINDING LESS AGREEMENT ON THE AFOREMENTIONED
FEATURES AND THEIR PLACEMENT AND STRENGTH.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 548 AM MDT THU SEP 11 2025
SOME LOW CIGS AND PATCHY FOG WILL BE POSSIBLE THIS MORNING,
PRIMARILY AT WESTERN NEBRASKA TERMINALS. IF LOW CIGS AND FOG DO
DEVELOP, MVFR TO IFR CONDITIONS CAN BE EXPECTED. ANY LOW
STRATUS AND FOG WILL LIKELY CLEAR BY THE AFTERNOON. LATER IN THE
DAY, SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
VISIBILITY REDUCTIONS DUE TO HEAVY RAIN CANNOT BE RULED OUT.
HAIL AND STRONG WINDS WILL ALSO BE POSSIBLE IN STRONGER STORMS.
STORMS WILL CONTINUE INTO THE EVENING HOURS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...SF
LONG TERM...CG
AVIATION...SF
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