481
FXUS65 KCYS 031742
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
ISSUED BY NATIONAL WEATHER SERVICE RIVERTON WY
1142 AM MDT THU SEP 3 2026
KEY MESSAGES
- RED FLAG WARNING IN EFFECT FOR CONVERSE AND NIOBRARA
COUNTIES.
- WARMING AND DRYING TREND EXPECTED THROUGH THE END OF THE WEEK.
- PRECIPITATION CHANCES RETURN FOR THE BEGINNING OF NEXT WEEK.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 327 AM MDT THU SEP 3 2026
LOOKING AT MID-LEVEL WATER VAPOR, THERE ARE TWO LOW PRESSURE
SYSTEMS OVER THE PACIFIC NORTHWEST AND ADJACENT CANADIAN
PROVINCES. AS THE RIDGE STARTS TO RETROGRADE TO THE WEST, IT IS
PUSHING THESE SYSTEMS FURTHER NORTH INTO THE CANADIAN PROVINCES.
THIS RIDGE WILL INCREASE THE HEIGHT GRADIENT BETWEEN THE
SYSTEMS IN THE PACIFIC NORTHWEST AND THE RIDGE, CAUSING BREEZY
CONDITIONS TOMORROW. THE DRY AIR MASS CURRENTLY SITTING OVER
EASTERN COLORADO/WESTERN KANSAS WILL BE ADVECTED NORTHWARD INTO
OUR REGION. THIS DRY AIR MASS WILL LIMIT THE AMOUNT OF AVAILABLE
MOISTURE OVER THE REGION AND DROP AFTERNOON DEWPOINTS INTO THE
LOW TEENS AND SINGLE DIGITS. A RED FLAG WARNING WAS ISSUED FOR
CONVERSE AND NIOBRARA COUNTY AS THE BREEZY WINDS WILL OVERLAP
WITH THE LOWER DEWPOINTS FOR THE REQUIRED 3 HOURS. PLATTE AND
GOSHEN COUNTY COULD ALSO HAVE RED FLAG CONDITIONS HOWEVER IT WAS
UNCERTAIN IF THE STRONGER WINDS WOULD LAST THE REQUIRED MINIMUM
OF 3 HOURS BEFORE THE RIDGE CUTS OFF THOSE BREEZY WINDS. WARMER
TEMPERATURES ARE TO BE EXPECTED TODAY AND FRIDAY WITH MINIMAL
TO NO SHOWER ACTIVITY AS THE CONVECTIVE TEMPERATURE REMAINS IN
THE MID 90S ACCORDING TO THE MODEL SOUNDINGS. THE MORE
MOUNTAINOUS AREAS CAN EXPECT TO REMAIN BREEZY TODAY AND TOMORROW
AS THE GRADIENT WILL REMAIN RATHER COMPRESSED OVER THAT AREA.
BUT AREAS EAST OF THE I-25 CORRIDOR CAN EXPECT THE WINDS TO BE
LIGHTER FRIDAY THAN THEY WOULD BE THIS AFTERNOON. HIGH-RES
MODELS SHOW LITTLE TO NO CAPE OVER OUR FORECAST AREA FOR TODAY
AND FRIDAY ADDING HIGHER CONFIDENCE THAT THE DRY AIR MASS WILL
BE ADVECTING OVER OUR AREA AND CUTTING OFF THE MOISTURE SUPPLY.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 201 PM MDT WED SEP 2 2026
SATURDAY...SOUTHWEST FLOW ALOFT PREVAILS. LOOKS LIKE WITH A
MINOR STREAM OF THE MONSOONAL MOISTURE TAP, WE ANTICIPATE
ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS IN THE
AFTERNOON AND EVENING.
SUNDAY...THE PRECIPITABLE WATER VALUES INCREASE SOMEWHAT AS
MONSOONAL MOISTURE INCREASES. WITH THAT SAID, EXPECT SCATTERED
AFTERNOON SHOWERS AND THUNDERSTORMS TO FORM OVER AND NEAR OUR
SNOWY RANGE AND LARAMIE RANGE IN THE AFTERNOON DUE TO OROGRAPHIC
EFFECTS AND DIFFERENTIAL HEATING, WITH MOST OF THE CONVECTION
PROPAGATING OVER THE NEBRASKA PANHANDLE IN THE EVENING.
MONDAY...SOMEWHAT DRIER AIR ALOFT MOVES OVERHEAD UNDER
SOUTHWEST FLOW ALOFT, WHICH SHOULD CORRESPOND TO AN AREAL
DECREASE IN AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS.
TUESDAY AND WEDNESDAY...AGAIN, SOMEWHAT DRIER AIR INFILTRATES
OUR WESTERN COUNTIES USING PRECIPITABLE WATER VALUES, WITH A BIT
BETTER MOISTURE FURTHER EAST, THUS ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS EXPECTED MAINLY OVER THE MOUNTAINS AND
EASTWARD.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1142 AM MDT THU SEP 3 2026
VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD. A FEW TO SCATTERED
CUMULUS AND CIRRUS CLOUDS THIS AFTERNOON. WINDS OUT OF THE WEST TO
SOUTHWEST FOR MOST TERMINALS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE.
WINDS RELAX TONIGHT TO BECOME VARIABLE AFTER 01/02Z. A WEAK SHORTWAVE TROUGH
WILL PASS THROUGH FRIDAY MORNING TO CREATE SOME CLOUD COVERAGE. MOST OF
THIS COVERAGEPASSES BY AROUND THE END OF THE FORECAST PERIOD.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR WYZ417-418.
NE...NONE.
SHORT TERM...WFOCYS
LONG TERM...WFOCYS
AVIATION...WFOCYS
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