890
FXUS65 KCYS 301127
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
527 AM MDT WED SEP 30 2026
KEY MESSAGES
- A SLIGHT CHANCE OF RAIN IS POSSIBLE FOR THE SOUTHERN NEBRASKA
PANHANDLE WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING.
- COOLER TEMPERATURES CONTINUE THROUGH THURSDAY, BUT WARMER AND
DRIER WEATHER WILL PREVAIL FRIDAY THROUGH EARLY NEXT WEEK.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 259 AM MDT WED SEP 30 2026
A STRONG UPPER-LEVEL CLOSED LOW WILL TRAVERSE THE FOUR CORNERS
REGION TODAY, SENDING SOME MOISTURE NORTHWARD INTO THE INTERSTATE 80
CORRIDOR. THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM WILL MOVE
NORTHEASTWARD INTO KANSAS BY THE END OF THE DAY, BRINGING MINOR
CHANCES FOR PRECIPITATION. MOST MODELS, BOTH HI-RES AND
SYNOPTIC, ARE IN AGREEMENT THAT MOST, IF NOT ALL, PRECIPITATION
WILL STAY SOUTH AND EAST OF THE FORECAST AREA. HOWEVER, CANNOT
RULE OUT A LIGHT SHOWER OR TWO IN THE SOUTHERN NEBRASKA
PANHANDLE DURING THE AFTERNOON AND EVENING HOURS AS THE SURFACE
LOW MOVES INTO KANSAS. CURRENT SATELLITE IMAGERY SHOWS CLOUD
COVER BEGINNING TO PUSH INTO NORTHERN COLORADO. THESE CLOUDS
WILL EVENTUALLY MAKE THEIR WAY INTO SOUTHEAST WYOMING AND
WESTERN NEBRASKA. AS A RESULT, INCREASING CLOUDINESS CAN BE
EXPECTED THROUGHOUT THE DAY. THE CLOUD COVER WILL LEAD TO A COOL
DAY, BUT STILL SEASONABLE FOR THIS TIME OF YEAR WITH HIGHS IN
THE 60S AND 70S. CLOUDS WILL GRADUALLY DECREASE WEDNESDAY NIGHT,
WITH A STRAY SHOWER STILL POSSIBLE OVERNIGHT FOR THE SOUTHERN
NEBRASKA PANHANDLE.
THURSDAY WILL MARK THE START OF A DRY PATTERN AS THE LOW PRESSURE
SYSTEM MOVES FURTHER EAST. CLOUDS WILL CONTINUE TO CLEAR OUT DURING
THE MORNING HOURS, LEADING TO MOSTLY SUNNY SKIES BY THE AFTERNOON.
UPPER-LEVEL RIDGING BUILDING OVER THE FOUR CORNERS REGION WILL HELP
CLEAR CLOUDS OUT AS WELL AS KEEP PRECIPITATION CHANCES LOW. HIGH
TEMPERATURES WILL BE SIMILAR TO WEDNESDAY WITH HIGHS IN THE 60S AND
70S. WITH MOSTLY CLEAR SKIES EXPECTED THURSDAY NIGHT, OVERNIGHT LOWS
WILL BE ON THE CHILLY SIDE WITH 40S AND POTENTIALLY A FEW 30S
POSSIBLE.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED AT 212 PM MDT TUE SEP 29 2026
GENERALLY TRANQUIL WEATHER WILL PERSIST THROUGH MUCH OF THE LONG-
TERM PERIOD. LARGE-SCALE RIDGING WILL DOMINATE THE WEATHER PATTERN
OVER THE WESTERN CONUS RESULTING IN GENERALLY MILD ABOVE-AVERAGE
TEMPERATURES AND LIMITED PRECIPITATION CHANCES OVER SOUTHEAST
WYOMING AND WESTERN NEBRASKA. THIS RIDGING PATTERN IS, BROADLY
SPEAKING, A GENERAL RESULT OF THE HIGHLY ACTIVE TROPICAL PATTERN
OVER THE EASTERN PACIFIC. AS THE FIREHOSE OF EPAC TROPICAL STORMS
MOVE WEST AND THEN RECURVE TO THE NORTH IN THE MID-LATITUDES OF THE
CENTRAL PACIFIC, POTENT SYNOPTIC TROUGHING IS NOTED OVER THE BEARING
SEA/GULF OF ALASKA WHICH THUS DRIVES DOWNSTREAM RIDGING OVER WESTERN
NORTH AMERICA. THESE TYPES OF STABLE-SYNOPTIC-WAVE PATTERNS CAN
OFTEN PERSIST FOR WEEKS OR MORE, LOCKING IN HIGH-CONFIDENCE
FORECASTS OVER MUCH OF THE WEST INCLUDING OUR REGION.
REGARDING LOCAL DETAILS IN THE FORECAST, EXPECT ABOVE-AVERAGE TEMPS
FROM FRIDAY ONWARD. HIGH CONFIDENCE EXISTS IN TEMPS AROUND 5 DEGREES
ABOVE AVERAGE THIS WEEKEND (LOW TO MID-70S EAST OF THE MOUNTAINS)
AND HIGHS 10 TO 15 DEGREES ABOVE AVERAGE THROUGH NEXT WEEK. DESPITE
THE DRIER WEATHER IN PLACE LATE THIS WEEK AND THROUGH THE WEEKEND,
RISING HEIGHTS SHOULD RESULT IN OVERNIGHT LOWS REMAINING ABOVE
AVERAGE AS WELL. THIS SHOULD HOLD OFF ANY THREATS OF FROSTS (OR
FREEZES) FOR ANY POPULATED AREA OF SOUTHEAST WYOMING OUTSIDE OF THE
MOUNTAINS. AFTERNOON RH VALUES WILL DROP TO NEAR OR SLIGHTLY BELOW
20% THROUGHOUT THE WEEKEND DURING THE AFTERNOON HOURS ACROSS ALL OF
SOUTHEAST WYOMING AND PORTIONS OF THE NEBRASKA PANHANDLE. HOWEVER,
GENERALLY LIGHT SURFACE FLOW OUT OF THE WEST LESS THAN 20 MPH WILL
LIKELY PRECLUDE THE NEED FOR ANY FIRE WEATHER HEADLINES. OVERALL,
GIVEN THE SYNOPTIC PATTERN DESCRIBED EARLIER IN THIS DISCUSSION,
FORECAST CONFIDENCE IS QUITE HIGH THROUGHOUT THE ENTIRE LONG-TERM
PERIOD WITH LIMITED IMPACTS EXPECTED.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 526 AM MDT WED SEP 30 2026
AVIATION IMPACTS WILL BE ON THE LOWER SIDE TODAY AS A STORM SYSTEM
PASSES TO THE SOUTHEAST OF WYOMING AND WESTERN NEBRASKA. SOME PATCHY
FOG WILL BE POSSIBLE THIS MORNING, MAINLY FOR TERMINALS IN THE
SOUTHERN NEBRASKA PANHANDLE. MVFR CONDITIONS ARE EXPECTED WITH ANY
FOG THAT DEVELOPS. FOG WILL DISSIPATE BY MID-MORNING, WITH VFR
CONDITIONS EXPECTED AFTERWARDS. INCREASING CLOUDINESS IS EXPECTED
THROUGHOUT THE DAY, WITH A CHANCE FOR LIGHT RAIN SHOWERS THIS
AFTERNOON AND EVENING IN THE SOUTHERN NEBRASKA PANHANDLE. MINIMAL
IMPACTS ARE EXPECTED FROM SHOWERS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...SF
LONG TERM...MAC
AVIATION...SF
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