543
FXUS65 KCYS 141744
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1144 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
SNOW LEVEL. 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/
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 /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1139 AM MDT SUN SEP 14 2025
AVIATION CONDITIONS ARE IMPROVING FOR WYOMING TERMINALS AS THE
STORM SYSTEM DEPARTS. EXPECT GRADUALLY CLEARING SKIES AND
OCCASIONALLY GUSTY WEST TO NORTHWEST WINDS. OVERNIGHT, WE WILL
SEE WINDS BEGIN TO INCREASE AROUND 2 KFT AGL AND THEN MIX TO THE
GROUND AROUND MID MORNING, PRODUCING SOME GUSTY WEST TO
SOUTHWEST WINDS.
IN NEBRASKA, SHOWER ACTIVITY IS EXPECTED TO CONTINUE FOR A FEW
MORE HOURS. ONCE THE STRATIFORM RAINFALL DEPARTS, WE WILL HAVE A
FEW MORE HOURS OF POTENTIAL FOR SCATTERED THUNDERSTORMS TO
DEVELOP IN MARGINAL INSTABILITY AND IMPACT NE TERMINALS WITH
LIGHTNING, RAIN, AND GUSTY WINDS. EXPECT GRADUAL CLEARING
OVERNIGHT TONIGHT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...TJT
LONG TERM...TJT/RUBIN
AVIATION...MN
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