400
FXUS65 KCYS 141146
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
545 AM MDT SUN SEP 14 2025
KEY MESSAGES
- WIDESPREAD RAINFALL AND SCATTERED THUNDERSTORMS CONTINUE FOR
EASTERN WYOMING AND WESTERN NEBRASKA THROUGH SUNDAY AFTERNOON.
- BRIEF WARMING TREND FOR MONDAY WITH HIGH TEMPERATURES
RETURNING TO THE 70S AND 80S.
- ANOTHER COLD FRONT WILL PUSH ACROSS WYOMING ON TUESDAY,
RESULTING IN COOLER TEMPERATURES AND A DAILY CHANCE FOR
SHOWERS AND ISOLATED THUNDERSTORMS.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 305 AM MDT SUN SEP 14 2025
IR SATELLITE LOOP AND UPPER LEVEL ANALYSIS SHOW THE MAIN UPPER
LEVEL TROUGH CURRENTLY NEAR THE WYOMING/NEBRASKA BORDER AND
ACROSS NORTHEAST COLORADO AT THIS HOUR. THIS TROUGH HAS BECOME A
BIT MORE NEGATIVELY-TILTED OVER THE LAST SEVERAL HOURS WITH
WRAP AROUND PRECIP/TROWAL-LIKE FEATURE OVER SOUTHEAST WYOMING
EXTENDING SOUTH TOWARDS THE MOUNTAINS OF NORTHERN COLORADO.
CURRENT KCYS RADAR LOOP SHOWS MAINLY LIGHT TO OCCASIONAL
MODERATE PRECIPITATION OVER THE AREA WITH A NOTABLE BRIGHT-BAND
SIGNATURE AROUND 50-70 MILES AWAY FROM THE RADAR...WHICH IS
ROUGHLY 10,000 TO 10,500 FEET AND LIKELY THE APPROXIMATE
SNOWLEVEL. OBSERVATIONS ACROSS THE SNOWY RANGE SHOW TEMPERATURES
IN THE LOW TO MID 30S BETWEEN 9500 TO 10500 FEET, WITH THE
FIRST SNOW OF THE SEASON FALLING IN SOME OF THESE LOCATIONS. THE
I-80 SUMMIT IS GETTING CLOSE AS WELL WITH VEDAUWOO AS LOW AS 39
DEGREES EARLY THIS MORNING. COULD SEE AN ADDITIONAL 1 TO 2
INCHES OF SNOW ABOVE 10000 FEET BEFORE THE PRECIPITATION BEGINS
TO DIMINISH SHORTLY AFTER SUNRISE. FURTHER EAST, MODERATE TO
HEAVY RAINFALL HAS FAILED TO MATERIALIZE, LIKELY DUE TO THE
DELAY IN (POTENTIAL) SURFACE CYCLOGENESIS ACROSS THE HIGH
PLAINS. MODELS NOW INDICATE THAT THE SURFACE LOW WILL BEGIN TO
GET GOING IN THE DAKOTAS LATER THIS MORNING. HOWEVER, IT HAS
BEEN RAINING LIGHTLY IN MOST LOCATIONS OVER MOST OF THE AREA
WITH THE EXCEPTION OF CARBON COUNTY LATE LAST NIGHT AND THIS
MORNING. A FEW LOCATIONS RECEIVED SOME PRETTY GOOD RAINFALL
AMOUNTS FROM YESTERDAY'S CONVECTION, BUT RAINFALL AMOUNTS OVER 1
INCH WERE PRETTY ISOLATED. AS THIS STORM SYSTEM SLOWLY TRACKS
NORTHEAST, EXPECT THE RAINFALL/HIGH ELEVATION SNOW TO COME TO AN
END FROM WEST TO EAST THIS MORNING. CAN'T RULE OUT ANOTHER BAND
OF SHOWERS AND THUNDERSTORMS FOR THE NORTHERN AND CENTRAL
NEBRASKA PANHANDLE THIS AFTERNOON, BUT NO SEVERE WEATHER IS
EXPECTED BEHIND THE UPPER LEVEL TROUGH. INCREASED HIGH
TEMPERATURES ON SUNDAY A FEW DEGREES BASED ON RECENT TEMPERATURE
TRENDS, BUT HIGHS WILL STILL REMAIN BELOW NORMAL FOR MID
SEPTEMBER.
MODELS CONTINUE TO INDICATE THE UPPER LEVEL TROUGH LIFTING
NORTHEAST INTO THE DAKOTAS LATE SUNDAY NIGHT AND MONDAY. EXPECT
DRIER CONDITIONS WITH INCREASING WESTERLY FLOW ALOFT WITH A MUCH
DRIER AIRMASS. EVEN THOUGH DEWPOINTS SHOULD SETTLE INTO THE
30S, SURFACE WINDS ACROSS THE HIGH PLAINS ARE FORECAST TO SHIFT
INTO THE SOUTH...WITH SOME LOW LEVEL MOISTURE ADVECTION
EXPECTED. INCREASED POP FOR WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS MONDAY AFTERNOON. IT WILL LIKELY BE OUR WARMEST
DAY OF THE WEEK WITH HIGH TEMPERATURES RETURNING TO THE MID 70S
TO MID 80S UNDER A SHORTWAVE RIDGE AXIS. THE NEXT UPPER LEVEL
PACIFIC TROUGH IS FORECAST TO MOVE SOUTHEAST ACROSS IDAHO AND
WYOMING BY TUESDAY MORNING. ALL MODELS IN GOOD AGREEMENT WITH
THIS FEATURE WITH LITTLE TO NO VARIABILITY IN TIMING. ANOTHER
COLD FRONT WILL PUSH ACROSS THE AREA ON TUESDAY RESULTING IN
TEMPERATURES FALLING BACK INTO THE 60S AND LOW/MID 70S WITH A
BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE EVENING
HOURS.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY NIGHT/
ISSUED AT 315 AM MDT SUN SEP 14 2025
LONG RANGE FORECAST REMAINS ON TRACK, SHOWING NORTHWEST FLOW
THROUGH THE MIDDLE OF THE WEEK AND A FALL-LIKE PATTERN AS WE
HEAD INTO WEDNESDAY AND THURSDAY. WEDNESDAY WILL LIKELY BE OUR
COOLEST DAY WITH HIGHS IN THE 60S TO LOW 70S...AND POSSIBLY
REMAINING IN THE UPPER 50S DURING THE DAY FOR THE HIGH VALLEYS
WEST OF I-25. WILL HAVE TO KEEP AN EYE ON LOW TEMPERATURES WITH
FROST OR LIGHT FREEZE POSSIBLE FOR THESE SAME HIGH VALLEY
LOCATIONS, OTHERWISE...MOST PLACES WILL SEE LOW TEMPERATURES IN
THE LOW TO MID 40S EACH MORNING THROUGH THURSDAY. ONE KEY MODEL
DIFFERENCES IS A SECONDARY UPPER LEVEL DISTURBANCE DIGGING SOUTH
OUT OF CANADA THURSDAY...BRINGING ANOTHER SHOT OF COOLER AIR TO
THE PLAINS WITH 700MB TEMPERATURES LOWERING TO AROUND 0C. THIS
IS RESULTING IN LARGE ENSEMBLE TEMPERATURE SPREADS AS WE HEAD
INTO LATE NEXT WEEK. THE UPPER LEVEL RIDGE AXIS ACROSS THE FOUR
CORNERS IS THEREFORE SUPPRESSED FURTHER SOUTHWARD LATER IN THE
WEEK AND NEXT WEEKEND. ELECTED TO LOWER TEMPERATURES CLOSER TO
CLIMO FOR DAYS 6 AND 7 WITH "DECENT" DETERMINISTIC MODEL
AGREEMENT AND ENSEMBLES SHOWING PRETTY LARGE SPREAD IN FORECAST
TEMPERATURES. LOW CONFIDENCE IN PRECIPITATION FORECASTS PAST
WEDNESDAY DUE TO DRIER NORTHWEST FLOW ACROSS THE REGION.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 545 AM MDT SUN SEP 14 2025
STORM SYSTEM WILL LIFT NORTHEAST INTO THE DAKOTAS TODAY WITH LIGHT
RAIN CONTINUING THIS MORNING ACROSS EASTERN WYOMING AND WESTERN
NEBRASKA. RAIN WILL END FROM WEST TO EAST BY THIS AFTERNOON.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL PREVAIL FOR ALL
TERMINALS WITH OCCASIONAL MVFR VIS AND CIGS AT KLAR, KCYS AND
POSSIBLY KSNY IN THE MODERATE RAIN SHOWERS. RAIN SHOULD END BY 18Z
FOR KCYS AND KLAR, BUT NOT UNTIL 21Z FOR KSNY AND KBFF. CAN'T RULE
OUT A FEW THUNDERSTORMS AFTER 21Z FOR KAIA AND KCDR. CLEARING SKIES
EXPECTED TONIGHT WITH OCCASIONALLY GUSTY SOUTHERLY WINDS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...TJT
LONG TERM...TJT/RUBIN
AVIATION...TJT
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