213
FXUS65 KCYS 161659
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
ISSUED BY NATIONAL WEATHER SERVICE RAPID CITY SD
1059 AM MDT WED JUL 16 2025
KEY MESSAGES
- SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED
WEDNESDAY AFTERNOON AND EVENING IN SOUTHEAST WYOMING AND
SOUTHWEST NEBRASKA. LARGE HAIL IS THE PRIMARY THREAT, BUT ALL
SEVERE WEATHER HAZARDS ARE POSSIBLE.
- WARMER TEMPERATURES AND ISOLATED TO SCATTERED LATE DAY
SHOWERS AND THUNDERSTORMS WILL OCCUR FOR THURSDAY THROUGH
EARLY NEXT WEEK.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 344 AM MDT WED JUL 16 2025
AN ACTIVE PERIOD OF WEATHER IS ANTICIPATED ACROSS THE AREA OVER
THE NEXT 24 HOURS OR SO. WATER VAPOR SATELLITE IMAGERY SHOWS A
POTENT UPPER LEVEL SHORTWAVE TROUGH MOVING ACROSS THE NORTHERN
ROCKIES. PLENTIFUL MOISTURE IS STREAMING OUT AHEAD OF THIS
SYSTEM OVER MUCH OF WYOMING AND NEBRASKA. MEANWHILE, A SURFACE
HIGH OVER THE NORTHER PLAINS IS PUSHED UP AGAINST THE EASTERN
EDGE OF THE ROCKIES, SUPPORTING SUBSTANTIAL LOW LEVEL MOISTURE
ADVECTION. PRECIPITABLE WATER VALUES EXCEED 1 INCH FOR MOST
ALONG AND EAST OF I-25, WHICH IS PUSHING THE 90TH TO 97.5
PERCENTILE OF CLIMATOLOGY. NEARLY SATURATED BOUNDARY LAYERS ARE
RESULTING IN LOW CLOUDS AND FOG PUSHING IN TO COVER MOST OF THE
HIGH PLAINS. THE LATEST MESOANALYSIS SHOWS FAIRLY POTENT
ISENTROPIC LIFT OVER MUCH OF THE AREA AHEAD OF THE UPPER LEVEL
SHORTWAVE. THIS IS SUPPORTING SCATTERED SHOWER AND THUNDERSTORM
ACTIVITY LINGERING WELL INTO THE NIGHT. ACTIVITY IS TAPPING INTO
SOME MODEST ELEVATED INSTABILITY, WHICH IS STRONGEST IN THE
GENERAL VICINITY OF THE LARAMIE RANGE. THIS WILL CONTINUE
THROUGH THE MORNING HOURS TODAY, WITH ISOLATED STORMS CAPABLE OF
PRODUCING SMALL HAIL. LARGE HAIL CANNOT BE RULED OUT THROUGH
THE MORNING.
ABUNDANT MOISTURE AND INSTABILITY CONTINUING WILL SET THE STAGE
FOR AN ACTIVE WEDNESDAY. CAPPING COULD PRESENT AN ISSUE FOR
SURFACE BASED CONVECTION, BUT FORCING LOOKS TO BE STRONG ENOUGH
TO ALLOW FOR STORMS TO TAP INTO ELEVATED INSTABILITY THANKS TO
CONTINUING OVERRUNNING FLOW. CAPPING LOOKS WEAKER ON THE WYOMING
SIDE. THIS WILL PUT THE MOST POTENT SEVERE WEATHER ENVIRONMENT
OVER ALBANY, PLATTE, GOSHEN, AND LARAMIE COUNTIES WEDNESDAY
AFTERNOON, WITH AMPLE DEEP LAYER SHEAR, STEEP MID- LEVEL LAPSE
RATES, AND PLENTIFUL INSTABILITY. THIS POINTS TO LARGE HAIL AS
THE MOST WIDESPREAD THREAT, BUT ALL SEVERE WEATHER HAZARDS WILL
BE POSSIBLE. STORM MOTIONS SHOULD BE FAIRLY FAST, BUT THERE IS A
POSSIBILITY FOR TRAINING STORMS. WITH THE PLENTIFUL MOISTURE IN
PLACE, ISOLATED FLASH FLOODING WILL BE ON THE TABLE TOO. THE
LOW-LEVEL INVERSION WILL BE STRONGER IN THE NEBRASKA PANHANDLE,
WHILE FORCING IS OVERALL WEAKER. THIS PUTS A LITTLE MORE
UNCERTAINTY INTO THE FORECAST FOR SOUTHWEST NEBRASKA. OVERALL
COVERAGE WILL PROBABLY BE MORE ISOLATED IN NE, BUT AN ISOLATED
STRONG TO SEVERE THUNDERSTORM WILL STILL BE POSSIBLE. FORCING
WILL CONTINUE WELL INTO THE EVENING ONCE AGAIN, BUT DRIER AIR IS
EXPECTED TO MOVE IN ALOFT AFTER MIDNIGHT. THIS SHOULD END
THUNDERSTORM ACTIVITY FOR ALL EXCEPT THE SOUTHERN NE PANHANDLE,
WHICH MAY CONTINUE FOR A FEW HOURS, BUT WIND DOWN BY ABOUT 3AM
THURSDAY MORNING AS ANOTHER ROUND OF LOW CLOUDS/FOG MOVES INTO
THE AREA.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
ISSUED AT 344 AM MDT WED JUL 16 2025
A ZONAL FLOW PATTERN WILL TAKE OVER ALOFT ON THURSDAY AND
DOMINATE MUCH OF THE NORTHERN HALF OF THE CONUS INTO THE
WEEKEND. DRIER WESTERLY FLOW ALOFT WILL REDUCE THE RISK FOR
STORMS ON THURSDAY, BUT ISOLATED THUNDERSTORMS WILL STILL BE
POSSIBLE, MAINLY ALONG THE I-80 CORRIDOR. MONSOON MOISTURE WILL
BE PULLED INTO THE FLOW ON FRIDAY, CAUSING PERCEPTIBLE WATER
AND MID-LEVEL MOISTURE IN GENERAL TO RECOVER. WHILE MID TO UPPER
LEVEL MOISTURE SHOULD IMPROVE FOR FRIDAY, THE DRYLINE IS
EXPECTED TO BE POSITIONED FURTHER EAST, RESULTING IN FAIRLY
STEADY PRECIPITABLE WATER THURSDAY INTO FRIDAY. EXPECT TO SEE
SOME HIGH-BASED SHOWERS AND THUNDERSTORMS WITH GUSTY WINDS
POSSIBLE ON FRIDAY ALONG WITH WARM TO HOT TEMPERATURES.
ENSEMBLES INDICATE THAT THE DRYLINE WILL MOVE BACK TO THE WEST
ON SATURDAY WHILE DECENT MID TO UPPER LEVEL MONSOON MOISTURE
REMAINS IN PLACE. EXPECT THIS TO THEN BRING THE HIGHEST CHANCE
FOR MORE WIDESPREAD SHOWER AND THUNDERSTORM COVERAGE OF THE LONG
TERM PERIOD. FOR SUNDAY THROUGH TUESDAY OR SO, EXPECT DECENT
MONSOON MOISTURE TO REMAIN IN PLACE ALOFT, BUT WE MAY LOSE THE
BOUNDARY LAYER MOISTURE FOR SEVERAL DAYS, LEADING TO MORE
ISOLATED PM THUNDERSTORM ACTIVITY EACH OF THOSE DAYS.
ADDITIONALLY, AN UPPER LEVEL TROUGH DIGGING INTO THE NORTHWEST
WILL AMPLIFY THE DOWNSTREAM RIDGE OVER THE CENTRAL PLAINS,
LEADING TO ANOTHER WARM TREND TO CARRY THROUGH THE MIDDLE PART
OF NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1050 AM MDT WED JUL 16 2025
LOW STRATUS CONTINUES FOR AREAS EAST OF THE LARAMIE RANGE LATE
THIS MORNING. LOW CIGS WILL LIKELY BURN OFF EARLY THIS
AFTERNOON, ALLOWING DESTABILIZATION FOR STORMS TO FORM. THE MAIN
AVIATION CONCERN THIS AFTERNOON WILL BE STRONG TO SEVERE STORMS
WITH HEAVY RAIN. MODERATE TO HEAVY RAIN WILL LIKELY LEAD TO
VISIBILITY DROPS IN ANY STORMS PASSING OVER A TERMINAL. MVFR TO
IFR VISIBILITY WILL BE POSSIBLE IN HEAVY RAIN. STRONG, GUSTY
WINDS AND LARGE HAIL WILL ALSO BE POSSIBLE IN STORMS THIS
AFTERNOON AND EVENING. MORE LOW STRATUS WILL BUILD IN LATE
TONIGHT AND CONTINUE THROUGH THURSDAY MORNING.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...
LONG TERM...
AVIATION...SF
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