448
FXUS65 KCYS 220349
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
949 PM MDT WED OCT 21 2026
KEY MESSAGES
- ABOVE AVERAGE TEMPERATURES WILL CONTINUE THROUGH THE END OF
THE WEEK, BUT A WEEKEND SYSTEM WILL DROP TEMPERATURES TOWARDS
NEAR TO BELOW-AVERAGE.
- PRECIPITATION POSSIBLE FRIDAY THROUGH SUNDAY, WITH THE
POTENTIAL FOR FROZEN PRECIPITATION OUTSIDE OF THE MOUNTAINS
ON SUNDAY.
- SOME CLEARING AND WARMING BACK TO NEAR NORMAL TEMPERATURES
NEXT WEEK, WITH SOME LOW END PRECIPITATION CHANCES MOSTLY IN
THE HIGH TERRAIN.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 230 PM MDT WED OCT 21 2026
THE OVERALL PATTERN THROUGH THURSDAY NIGHT SHOULD REMAIN LARGELY
UNCHANGED AS OUR REGION WILL SIT BETWEEN TWO STOUT SYSTEMS, WITH
A DEEP UPPER LEVEL RIDGE OVER THE CENTRAL US, AND A DEEP UPPER
LEVEL PACIFIC LOW MOVING INLAND AND THEN SLOWLY NORTHEASTWARDS.
THIS WILL CONTINUE TO PRODUCE A SOUTHWESTERLY FLOW THAT WILL
INCREASE MOISTURE ACROSS THE REGION, PARTICULARLY LATER INTO
THURSDAY AND MOVING INTO THE WEEKEND. FOR THE REST OF THIS
EVENING AND OVERNIGHT, INCREASING CLOUDINESS IS SEEN ON
SATELLITE PRIMARILY ACROSS CARBON AND ALBANY COUNTIES WHERE THE
HIGHEST INFLUX OF MOISTURE IS MOVING IN FOR THE DAY. WE COULD
SEE A FEW LIGHT SHOWERS ACROSS THIS AREA, AND SOME EARLIER RUNS
OF CAMS WERE PRODUCING EVEN A WEAK ECHO AS FAR EAST AS LARAMIE
COUNTY, BUT OVERALL PROBABILITIES ARE ON THE LOW SIDE ALONGSIDE
LOW CONFIDENCE.
CLOUDINESS WILL OVERSPREAD THE REGION ON THURSDAY THOUGH AS THE
MOISTURE CONTINUES TO INCREASE. WHILE THIS COULD IMPACT
AFTERNOON HIGHS FOR THE WESTERN HALF OF THE FORECAST AREA, 700
MB TEMPERATURES REMAIN AT AROUND 7-10 C WHICH SHOULD ENCOURAGE
HIGHS SIMILAR TO TODAY IN THE 60'S TO 70'S. CAMS ARE MUCH MORE
EXCITED FOR PRECIPITATION EXTENDING OUT OF THE HIGH TERRAIN
TOMORROW AFTERNOON AND EVENING, WITH A CHANCE OF SHOWERS ACROSS
MUCH OF THE I-80 CORRIDOR THROUGH NEBRASKA. WHILE STORM CHANCES
ARE LARGELY DECLINING AS WE ENTER THE COLD SEASON, A BRIEF
SWATH OF CAPE AROUND 200-300 J/KG ACROSS CARBON COUNTY COULD
ENCOURAGE A RUMBLE OF THUNDER OR TWO, BUT DON'T EXPECT MUCH OUT
OF THIS ACTIVITY. OTHERWISE CLOUDINESS SHOULD LINGER THROUGH THE
NIGHTTIME HOURS WHICH WILL ALLOW FOR OVERNIGHT LOWS TO REMAIN
ON THE WARM SIDE DUE TO INSULATION, WITH UPPER 40'S TO 50'S
ACROSS EASTERN WYOMING AND THE NEBRASKA PANHANDLE AS WE MOVE
INTO THE WEEKEND.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 230 PM MDT WED OCT 21 2026
ON FRIDAY THE UPPER LEVEL PACIFIC SYSTEM WILL BE APPROACHING FROM
THE SOUTHWEST. AHEAD OF IT A FEW IMPULSES OF MID AND LOW LEVEL
VORTICITY ARE PROGGED TO PASS OVER THE AREA, ALLOWING SHOWERS TO
EXIST OVER MOSTLY THE INTERMOUNTAIN AREAS. IN ADDITION, A JET STREAK
OF ABOUT 80-100 KNOTS INTENSIFIES AHEAD OF THE SYSTEM. THE PHASE OF
THE JET AND IMPULSES ARE SOMEWHAT MISTIMED TO ALLOW FOR MORE
WIDESPREAD PRECIPITATION. THE JET WILL SUPPRESS THE DEVELOPMENT OF
PRECIPITATION DUE TO A HEALTHY AMOUNT OF POSITIVE OMEGA BELOW 500
MBAR. THE EXCEPTIONS ARE IN THE NEBRASKA PANHANDLE WHERE THE
ENTRANCE REGION OF THE JET MAY BE MORE FAVORABLE. IT ALSO HELPS THAT
THIS REGION WILL HAVE MORE MOISTURE AND INSTABILITY TO WORK WITH.
SKEW-T PROFILES HAVE ABOUT 500 MUCAPE AND 60 KNOTS OF SPEED SHEAR TO
PERHAPS PROP UP A FEW THUNDERSTORMS AT AND AFTER PEAK DAYTIME
HEATING. NO SEVERE WEATHER IS ANTICIPATED WITH ANY STORM, THOUGH
SMALL HAIL IS A PROBABILITY GIVEN THE SHEAR. THE CLEARING CLOUD
COVERAGE TO THE EAST ALLOWS MUCH OF THE PANHANDLE TO REACH THE MID
70 TO LOW 80S IN THE AFTERNOON. MOVING WEST, THE CLOUD COVERAGE
INCREASES, ONLY ALLOWING SOUTHEAST WYOMING TO MAKE IT INTO THE MID
60S TO LOW 70S. OVERNIGHT A COLD FRONT IS EXPECTED TO MAKE ITS WAY
SOUTHEAST THROUGH THE AREA. A 10 DEGREE DROP FROM THURSDAY OVERNIGHT
LOWS IS LIKELY, WITH LOWS IN THE MID 30S TO LOW 40S.
RETURNING TO THE UPPER LEVEL SYSTEM TO OUR WEST. THE EVOLUTION
THROUGH FRIDAY IS FOR THE TROUGH TO SPLIT AND ELONGATE. THE NORTHERN
PORTION GETS PICKED UP BY A STRONG NEGATIVELY TILTED TROUGH IN
CANADA, WHILE THE SOUTHERN END OF THE TROUGH REMAINS OVER THE
SOUTHWEST. THIS SOUTHERN LOBE OF THE SYSTEM WILL BE THE DRIVER OF
MORE EXCITING WEATHER GOING INTO SUNDAY AND MONDAY.
POST FRONT SATURDAY IS ANTICIPATED TO BE BREEZY AND PARTLY TO MOSTLY
CLOUDY. WINDS BEHIND THE FRONT COULD BE FRESH WITH GUSTS TO 40 MPH
POSSIBLE. A FEW SHOWERS ARE POSSIBLE AS THEY DRIFT NORTH FROM THE
ADVECTION ACTIVITY IN COLORADO, BUT OTHERWISE A DRY DAY.
TEMPERATURES STRUGGLE TO MAKE IT TO 60, WITH MOST OF US STAYING IN
THE 50S. SUNDAY THE REMAINING PACIFIC SYSTEM MOVES NORTHEAST
BRINGING WITH IT MORE CHANCES FOR PRECIPITATION. THE GFS IS PICKING
UP ON A POSSIBLE TROWL SETTING UP OVER OUR NORTHERN COUNTIES.
TEMPERATURES ARE MARGINAL FOR ANY ACCUMULATION OF SNOW, BUT A MIX OF
SNOW AND RAIN AT THE SURFACE IS POSSIBLE. AT OUR PEAKS AN INCH OR
TWO OF SNOW MAY BE POSSIBLE.
FOLLOWING THE SYSTEM A RIDGE BUILDS IN BEHIND IT. CLEARING SKIES AND
A GRADUAL WARMING TREND. THE NEXT STORM SYSTEM IS BEING ADVERTISED
IN THE GFS, HOWEVER THERE ARE SIGNIFICANT RUN TO RUN VARIABILITY IN
THE TIMING AND POSITIONING OF THIS SYSTEM. THE ECMWF IS TELLING A
SIMILAR STORY, ALTHOUGH THE SYSTEM IS MUCH FLATTER AND SLOWER.
PRECIPITATION CHANCES WOULD BE ON THE LOWER SIDE WITH THIS SYSTEM
WITH NOT MUCH SYNOPTICALLY TO REFILL THE MOISTURE RESERVE AHEAD OF
THE TROUGH AND NOT MUCH ATTENDANT WITH THE AIRMASS ASSOCIATED WITH
IT.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 949 PM MDT
WED OCT 21 2026
A VARIETY OF HAZARDS ARE EXPECTED THROUGH THE TAF PERIOD AHEAD OF A
POTENT CLOSED LOW THAT WILL INTRODUCE PRECIPITATION CHANCES TOMORROW
AFTERNOON AND INTO THE EVENING HOURS. OVERALL, VFR IS EXPECTED TO
PREVAIL OVERNIGHT INTO TOMORROW MORNING AS A FEW MID AND HIGH CLOUDS
ARE EXPECTED OVER THE REGION. ONE EXCEPTION IS THAT KAIA, KSNY, AND
KBFF MAY SEE SOME LOW CLOUD DEVELOPMENT AFTER 10Z, BUT CONFIDENCE IS
TOO LOW BASED OFF RECENT HREF GUIDANCE, SO REMOVED MVFR CIGS DUE TO
THIS TREND. PRECIPITATION WILL BEGIN FROM WEST TO EAST TOMORROW
AFTERNOON, WITH KRWL AND KLAR BEING IMPACTED FIRST, PRIMARILY AFTER
18Z. CAN'T RULE OUT THE ODD LIGHTNING STRIKE OR TWO GIVEN WEAK
INSTABILITY, BUT COVERAGE AND CONFIDENCE ISN'T HIGH ENOUGH TO
INCLUDE A PROB30 GROUP AT THIS TIME. WINDS WILL BE ANOTHER CONCERN
OVERNIGHT INTO TOMORROW, MAINLY FOR THE WYOMING TERMINALS AND KCDR
WHERE SOUTHERLY GUSTS PEAKING UP TO 25-30 KNOTS WILL BE
POSSIBLE.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...CG
LONG TERM...RV
AVIATION...NB
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