775
FXUS65 KCYS 130915
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
315 AM MDT THU AUG 13 2026
KEY MESSAGES
- MONSOON MOISTURE HAS RETURNED TO THE AREA, INCREASING STORM
CHANCES THROUGH THE WEEKEND AND BRINGING TEMPERATURES DOWN TO
NEAR OR BELOW SEASONAL AVERAGES.
- SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED WEDNESDAY.
STRONG WINDS, LARGE HAIL, AND LOCALIZED FLASH FLOODING ARE THE
PRIMARY CONCERNS.
- NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED
THURSDAY WITH ISOLATED STRONG TO SEVERE STORMS AND FLASH
FLOODING POSSIBLE.
- A WARMING TREND EARLY NEXT WEEK MAY BRING US BACK TO NEAR
NORMAL LATE SUMMER WARMTH.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 315 AM MDT THU AUG 13 2026
FORECAST FOR TODAY IS A BIT MORE TRICKY THAN YESTERDAY AS WE TRY
TO NAVIGATE THE PITFALLS OF THUNDERSTORM POTENTIAL FOR THE DAY.
THERE IS PLENTIFUL MOISTURE ACROSS THE REGION AS EVIDENCED BY
THE LOW CLOUD CEILINGS, AND AREAS IN THE NEBRASKA PANHANDLE
ALREADY SEEING LOWERED VISIBILITY FROM MIST OR PATCHY FOG. PWAT
VALUES ARE EXPECTED TO REACH THEIR MAXIMUM, AT AROUND 150-170%
OF NORMAL. THIS SHOULD ROUGHLY EQUATE TO AROUND 1.25-1.5 INCHES
EAST OF THE LARAMIE RANGE. BUT THE MAIN ISSUE WILL BE OUR
ABILITY TO PRODUCE STRONGER SHOWERS AND THUNDERSTORMS TODAY.
SOUNDING PROFILES FOR OUR SOUTHERN ZONES FROM LARAMIE COUNTY AND
THE SOUTHERN PORTIONS OF PLATTE AND GOSHEN COUNTIES THROUGH THE
SOUTHERN NEBRASKA PANHANDLE SHOW A MODEST ENVIRONMENT INCLUDING
AREAS OF MUCAPE IN THE NEIGHBORHOOD OF 700-1500 J/KG AND LAPSE
RATES THAT COULD GET AS HIGH AS 8 C/KM, BUT CONVECTIVE
INHIBITION MAY PUT A DAMPER ON THIS POTENTIAL. ALL OF THIS NOT
TO MENTION DAYTIME HEATING WILL BE STIFLED BY THE WIDESPREAD
CLOUD COVER FROM THE ABUNDANT MOISTURE MEANS STORMS WILL NEED TO
WORK TO BE STRONG ENOUGH TO CAUSE ISSUES. BUT IF STRONGER
STORMS CAN OCCUR, WE COULD SEE RAINFALL RATES IN EXCESS OF 1-2
INCHES PER HOUR, OR THE POTENTIAL FOR TRAINING ACTIVITY DROPPING
SEVERAL ROUNDS OF RAINFALL OVER THE SAME LOCATION(S), ALONGSIDE
A MEAGER SEVERE RISK FOR THE AFOREMENTIONED REGION. A MARGINAL
SEVERE RISK FOR HAIL AND/OR STRONG WINDS IS EXPECTED FOR THE
AFOREMENTIONED AREA, AND WE HAVE COLLABORATED WITH OUR
NEIGHBORS IN BOULDER TO ISSUE A FLOOD WATCH TO INCLUDE LARAMIE
COUNTY AND THE SOUTHERN NEBRASKA PANHANDLE UP THROUGH BOTH
SCOTTSBLUFF AND ALLIANCE. WHILE THE STRONGEST STORMS MAY STAY
JUST SOUTH OF ALLIANCE, THINKING WAS THAT THE EASTERN HALF OF
THIS AREA SAW FAIRLY DECENT RAINFALL YESTERDAY INCLUDING
ALLIANCE ITSELF AT JUST UNDER 1.5 INCHES, AND SO IF WE CAN GET
FURTHER NOTABLE PRECIPITATION HERE THEN A FLOOD RISK WILL BE
POSSIBLE. OTHERWISE TODAY THE WIDESPREAD CLOUD COVER WILL KEEP
US THE COOLEST WE'VE BEEN IN A WHILE, WITH HIGHS ONLY REACHING
THE 70'S FOR MOST OF OUR AREA.
MOVING INTO FRIDAY PWAT VALUES WILL DESCEND JUST A BIT, BUT
WE'LL STILL BE LOOKING AT 130-150% OF NORMAL. CLEARING CLOUDS
DURING THE MORNING INTO THE AFTERNOON MAY ALSO PROMOTE A BIT
BETTER DAYTIME HEATING AND THEREBY FUELING INSTABILITY AND LAPSE
RATES (1000-2000 J/KG AND 8-9 C/KM RESPECTIVELY). THIS HAS
HELPED TO EXPAND THE SEVERE RISK INTO OUR AREA, WITH ANOTHER
MARGINAL RISK FOR HAIL AND/OR WINDS FOR LARAMIE COUNTY AND INTO
THE SOUTHERN NEBRASKA PANHANDLE. THIS AREA WILL ALSO BE AT THE
MOST NOTABLE RISK FOR EXCESSIVE RAINFALL. CAMS GET ANOTHER
ROUND OF ACTIVITY GOING AS WE HEAT UP DURING THE EARLY AFTERNOON
WITH A DECENT LINE OR TWO OF FRESH STORMS OFF THE HIGH TERRAIN
AND MULTIPLE ROUNDS OF ACTIVITY POSSIBLE THROUGH THE AFTERNOON
AND INTO THE EVENING. ONCE AGAIN JUST LIKE THE PREVIOUS COUPLE
OF DAYS THOUGH, OUTFLOW DEBRIS AND ONGOING ACTIVITY WILL LIKELY
BEGIN TO STABILIZE THE ATMOSPHERE AND LIMIT OUR STRONGEST
POTENTIAL TO EARLIER ON. BUT THE INCREASED HEATING WILL WARM US
BACK UP, WITH TEMPERATURES 6-12 DEGREES WARMER THAN THURSDAY.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED AT 245 PM MDT WED AUG 12 2026
AS THE LONG TERM PERIOD PROGRESSES, THE RIDGE STARTS FLATTENING OUT
AS A LOW APPROACHES FROM THE PNW. SHORTWAVES MOVE NORTHWARD TOWARD
OUR REGION WHICH BRINGS WIDESPREAD CHANCES FOR SHOWERS AND
THUNDERSTORMS TO OUR AREA. THIS MOISTURE IS STILL COMING INTO THE
AREA AS MONSOONAL MOISTURE. PRECIPITABLE WATER VALUES STAY AROUND
THE 90TH PERCENTILE RANGE, SLOWLY TAPERING OFF THROUGH THIS LONG
TERM PERIOD. WITH THIS PLENTIFUL MOISTURE, THERE IS HIGHER
CONFIDENCE IN PRECIPITATION EACH DAY THROUGH THIS PERIOD.
PRECIPITATION CHANCES ARE GREATEST IN THE AFTERNOON TO EVENING HOURS
THROUGH THE CWA. 700MB TEMPERATURES ARE AROUND 10-15C BRINGING US
SEASONAL DAYTIME HIGHS AND OVERNIGHT LOWS.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1125 PM MDT WED AUG 12 2026
DIFFICULT TAF FORECAST WITH TIMING AND PINPOINTING WHEN OR IF A
TERMINAL WILL GET IMPACTED BY SHOWERS AND/OR THUNDERSTORMS. IF
A STORM COMES NEAR OR GOES OVER A TERMINAL, EXPECT GUSTY AND
ERRATIC WINDS. WITH THE ADDED MOISTURE FROM WEDNESDAY'S STORMS,
DECREASE IN VIS IS POSSIBLE IN BR AND/OR FG AT KCYS, KBFF, KCDR,
KSNY, AND KAIA. THIS WILL BE POSSIBLE THROUGH MOST OF THE NIGHT
AND END BY SUNRISE. ADDITIONAL STORMS ARE LIKELY THURSDAY,
BRINGING INCREASED CHANCES OF THUNDERSTORMS. SINCE THE
CONVECTIVE NATURE, KEPT PROB30S OUT OF THE TAFS AND USED VCTS
DUE TO LOW CONFIDENCE.
CYS WATCHES/WARNINGS/ADVISORIES
WY...FLOOD WATCH FROM 3 PM MDT THIS AFTERNOON THROUGH THIS EVENING
FOR WYZ117>119.
NE...FLOOD WATCH FROM 3 PM MDT THIS AFTERNOON THROUGH THIS EVENING
FOR NEZ003-019>021-054-055.
SHORT TERM...CG
LONG TERM...ML
AVIATION...RZ
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