282
FXUS65 KCYS 080817
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
217 AM MDT FRI AUG 8 2025
KEY MESSAGES
- AN ISOLATED STRONG TO SEVERE THUNDERSTORM CANNOT BE RULED OUT
THIS AFTERNOON/EVENING, MAINLY IN THE NORTHERN NE PANHANDLE
AND EAST CENTRAL WY.
- RED FLAG WARNINGS REMAIN IN EFFECT THROUGH FRIDAY DUE TO LOW
AFTERNOON RELATIVE HUMIDITY AND POOR OVERNIGHT HUMIDITY
RECOVERIES.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 217 AM MDT FRI AUG 8 2025
A COLD FRONT WILL PUSH THROUGH THIS AFTERNOON TO BRING US SOME
RELIEF FROM THOSE UPPER 90'S TO LOW 100 DEGREE TEMPERATURES. MODEL
SOUNDING STILL SHOW SOME DRY AIR ALONG THE SURFACE EVEN WITH SOME
MOISTURE ADVECTION ASSOCIATED WITH THIS FRONT. THIS INVERTED "V"
SOUNDING SUGGEST GUSTY SHOWERS TOMORROW AROUND 45 KNOTS WITH THE
DEEP MIXING PROFILE. THIS IS A SLIGHT FIRE WEATHER CONCERN AS SOME
AREAS MAY EXPERIENCE DRY LIGHTNING. OTHERWISE THERE IS A MARGINAL
RISK FOR SEVERE STORMS. HI-RES GUIDANCE SHOWS THE MOST FAVORABLE
AREA IS THE NORTHEAST PORTION OF OUR FORECAST AREA. NIOBRARA,
GOSHEN, NORTHERN SIOUX, AND DAWES COUNTY LOOK TO BE IN THE BETTER
MOISTURE RETURN LOOKING AT THE GFS 700MB RH FIELD. HOWEVER, NAEFS
DEPICTS IVT TO BE IN THE 99TH PERCENTILE LATER THIS AFTERNOON AND
EVENING ALONG THE SOUTHERN PORTION OF OUR CWA. THERE DOES SEEM TO A
SLIGHT DISCONNECT BETWEEN THE VORTICITY FORCING AND THE TIMING OF
MOISTURE. WHILE THE GFS PROGGED THE STRONGEST MOISTURE RETURN TO
OCCUR AROUND 21Z THE VORTICITY GRADIENT ISN'T EXPECTED TO ARRIVE
UNTIL AFTER 00Z. THIS MAY LESSEN THE SEVERE POTENTIAL AS WE START
LOSING SUNLIGHT AND CAPE AROUND THAT TIME AS WELL. CAPE VALUES LOOK
TO BE BETWEEN 500-1000 AROUND THAT TIME WHICH MAY BE ENOUGH TO
DEVELOP SOME SEVERE STORMS. THERE ALSO LOOKS TO BE A RESURGENCE OF
SHOWERS INTO THE OVERNIGHT PERIOD FOLLOWING THE VORTICITY GRADIENT.
THIS MAY LEAD TO SOME OVERNIGHT CONVECTION WITH SOME CLAPS OF
THUNDER BUT NO SEVERE THUNDERSTORMS ARE EXPECTED DURING THIS TIME.
THESE SHOWERS MAY LAST UNTIL EARLY SATURDAY MORNING BEFORE MOVING
OUT OF OUR FORECAST AREA.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 231 PM MDT THU AUG 7 2025
ACTIVITY WILL CREEP UP AGAIN INTO THE WEEKEND AS AN UPPER LEVEL LOW
PASSES OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS. EXPECT COOLER
TEMPERATURES ON SATURDAY WITH HIGHS GENERALLY IN THE UPPER 70S TO
MID 80S UNDERNEATH THE SLOW MOVING TROUGH ALOFT. A DRY SLOT OF THE
UPPER LEVEL LOW IS EXPECTED TO CREEP INTO MUCH OF THE NORTHERN PART
OF THE FORECAST AREA, AND MIX DOWN VERY LOW DEWPOINTS IN THE
AFTERNOON HOURS. STILL, MOST GUIDANCE IS HOLDING ONTO A MORE MOIST
SURFACE ENVIRONMENT ALONG AND SOUTHEAST OF ROUGHLY A CHEYENNE TO
ALLIANCE LINE. CONVERGENCE ALONG THE DRYLINE MAY PROVIDE ENOUGH
FORCING TO KICK OFF SOME AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS. WHILE INSTABILITY DOESN'T LOOK TOO IMPRESSIVE, THERE
WILL BE PLENTY OF SHEAR PRESENT AND FAIRLY GOOD DEEP MOISTURE, AT
LEAST ON THE WET SIDE OF THE DRYLINE. A FEW SCATTERED STRONG TO
SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL COULD BE POSSIBLE
WITH SATURDAY'S ACTIVITY. THERE IS ALSO A CHANCE FOR FORCING TO
CONTINUE LATE INTO THE OVERNIGHT HOURS OR EVEN SUNDAY MORNING. AS A
RESULT, POPS ARE RETAINED FOR FAR SOUTHEAST WY AND THE SOUTHERN NE
PANHANDLE INTO SUNDAY MORNING.
EXPECT TEMPERATURES TO REACH THEIR MINIMUM ON SUNDAY WITH 700-MB
TEMPERATURES AROUND +7 TO +9C, WHICH IS ACTUALLY CLOSE TO THE
CLIMATOLOGICAL 10TH PERCENTILE. CLOUD COVER OVER THE SOUTHERN PART
OF THE FORECAST AREA MAY KEEP MUCH OF THE I-80 CORRIDOR IN THE MID
70S OR COOLER ON SUNDAY WHILE THE DRIER NORTHERN ZONES WILL STILL BE
COOLER THAN AVERAGE, BUT SHOULD STILL WARM TO THE LOW TO MID 80S.
LOOK FOR ANOTHER ROUND OF WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS, MAINLY ALONG/SOUTH OF THE NORTH PLATTE RIVER VALLEY.
CURRENT SOUNDINGS APPEAR TO BE MORE GARDEN-VARIETY THUNDERSTORMS
WITH SOME LOCALLY HEAVY RAINFALL THREAT, BUT THERE IS TIME FOR THIS
TO CHANGE. CIN MAY BE AN ISSUE FOR BOTH SATURDAY AND SUNDAY'S
CONVECTION.
EXPECT TO SEE A WARMING AND DRYING TREND THROUGH THE FIRST HALF OF
NEXT WEEK AS RIDGING TRIED TO BUILD BACK IN OVER THE WESTERN AND
CENTRAL CONUS.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1045 PM MDT THU AUG 7 2025
STRENGTHENING SOUTHWEST FLOW ALOFT EXPECTED TONIGHT AND FRIDAY AHEAD
OF A PRETTY STRONG UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT FOR
THIS TIME OF THE YEAR. THIS FRONT WILL MOVE SOUTH AND EAST ACROSS
THE NORTHERN ROCKYS AND INTO THE CENTRAL AND NORTHERN PLAINS THROUGH
THE DAY ON FRIDAY. WINDS ARE FORECAST TO BECOMING GUSTY AFTER
SUNRISE AND SHIFT INTO THE NORTH FRIDAY AFTERNOON WITH A SLIGHT
CHANCE OF THUNDERSTORMS.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL PREVAIL ACROSS THE
AREA TONIGHT AND INTO FRIDAY MORNING WITH INTERVALS OF MIDLEVEL
CLOUDINESS. ANY SMOKE OR HAZE FROM AREA WILDFIRES IS NOT EXPECTED TO
RESULT IN LOWER SURFACE VIS AT THIS TIME. ADDED PROB30 GROUPS TO THE
TERMINALS WITH THE BEST CHANCE OF THUNDERSTORMS LATE FRIDAY
AFTERNOON THROUGH THE LATE EVENING HOURS. COVERAGE SHOULD BE WIDELY
SCATTERED AT BEST WITH GUSTY WINDS THE PRIMARY THREAT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR WYZ419>429.
NE...NONE.
SHORT TERM...MM
LONG TERM...MN
AVIATION...TJT
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