888
FXUS65 KCYS 131752
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1152 AM MDT THU AUG 13 2026
KEY MESSAGES
- MONSOONAL MOISTURE HAS RETURNED TO THE AREA, INCREASING STORM
CHANCES THROUGH THE WEEKEND AND BRINGING TEMPERATURES DOWN TO
NEAR OR BELOW SEASONAL AVERAGES.
- 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 1150 AM MDT THU AUG 13 2026
SATURDAY...MOIST WESTERLY FLOW ALOFT AND A WEAK SHORTWAVE TROUGH
ALOFT NEAR PEAK HEATING WILL COMBINE WITH DEEP ATMOSPHERIC MOISTURE
SUPPLY TO PRODUCE SCATTERED TO NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS IN THE AFTERNOON AND EVENING, WITH THE GREATEST AREAL
COVERAGE EAST OF INTERSTATE 25. AIDING IN THE LIFT WILL BE LOW LEVEL
SOUTHEAST WINDS ADDING THE MECHANICAL LIFT IN ADDITION TO DIURNAL
HEATING. PWAT, PRECIPITABLE WATER VALUES LOOK DECENT FOR BENEFICIAL
RAINFALL. 700 MB TEMPERATURES YIELD HIGHS IN THE 70S TO LOWER 80S.
SUNDAY...RIDGING BECOMES A BIT MORE PRONOUNCED OVER WYOMING,
PRODUCING WARMER TEMPERATURES ALOFT WHICH WILL TEND TO LIMIT AREAL
COVERAGE OF SHOWERS AND THUNDERSTORMS, COMPARED TO SATURDAY.
NEVERTHELESS THOUGH, THE MONSOONAL MOISTURE WILL STRETCH FROM
CENTRAL COLORADO THROUGH FAR EASTERN WYOMING AND WESTERN NEBRASKA,
WHERE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL OCCUR IN
THE AFTERNOON AND EVENING. SLIGHTLY WARMER, BUT COMFORTABLE,
TEMPERATURES FOR THIS TIME IN AUGUST.
MONDAY...A DRIER PATTERN ENSUES AND IS ON TAP AS THE FLOW ALOFT
TURNS WEST NORTHWEST AND THE PRECIPITABLE WATER VALUES DECREASE, DUE
TO DRYING AT LOW AND MID LEVELS AND DOWNSLOPE SOUTHWEST WINDS NEAR
THE SURFACE. THUS, A MUCH DRIER DAY WHEN COMPARED TO THE WEEKEND. A
WARMING TREND BEGINS WITH MORE SUNSHINE AND WARMER MID LEVEL
TEMPERATURES.
TUESDAY...BRISK WESTERLY FLOW ALOFT PREVAILS, AND WITH A DECENT
AMOUNT OF LOW AND MID LEVEL MOISTURE AVAILABILITY, EXPECT ISOLATED
TO WIDELY SCATTERED LATE DAY SHOWERS AND THUNDERSTORMS, MAINLY EAST
OF INTERSTATE 25 AND THE LARAMIE RANGE. SIMILAR MAXIMUM TEMPERATURES
TO MONDAY BASED ON 700 MB TEMPERATURES.
WEDNESDAY...THE SYNOPTIC PATTERN LOOKS MORE LIKE SEPTEMBER AND EARLY
AUTUMN WITH A DEEP SHORTWAVE TROUGH ALOFT SWEEPING ACROSS WESTERN
MONTANA AND IDAHO, WITH WEST SOUTHWEST FLOW ALOFT OVER OUR COUNTIES.
RIGHT NOW, WE HAVE SCATTERED LATE DAY SHOWERS AND THUNDERSTORMS IN
OUR GRIDDED FORECASTS, THOUGH WITH A DECENT INCREASE IN PRECIPITABLE
WATER VALUES, THE MOIST FLOW ALOFT, AND LOW LEVEL UPSLOPE, ALONG
WITH PATTERN RECOGNITION, BELIEVE OUR POPS AND CONVECTIVE COVERAGE
WILL LIKELY NEED TO BE INCREASED IN THE NEXT FEW DAYS.
THURSDAY...THE HIGH AMPLITUDE AND PROGRESSIVE SHORTWAVE TROUGH ALOFT
MOVES EASTWARD FROM WESTERN MONTANA, TO THE DAKOTAS AND WESTERN
NEBRASKA BY EVENING, SENDING A DECENT PACIFIC ORIGIN COLD FRONT
ACROSS OUR COUNTIES. THERE MAY BE ENOUGH MOISTURE AT LOW AND MID
LEVELS FOR ISOLATED TO WIDELY SCATTERED CONVECTIVE COVERAGE, THOUGH
THE BIGGEST CHANGE WILL LIKELY BE A RETURN TO COOLER TEMPERATURES
AND WINDY DOWNSLOPE WEST WINDS, WHICH WILL LIKELY NEED TO BE
ADJUSTED IN THE NEXT FEW DAYS, IF MODEL CONSISTENCY REMAINS FOR DAY
7. IF YOU ARE LOOKING FOR AN EARLY TASTE OF FALL WEATHER, THIS MAY
BE YOUR DAY.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1146 AM MDT THU AUG 13 2026
LOW CLOUDS, FOG, AND NUMEROUS SHOWERS AND THUNDERSTORMS WILL
CREATE SEVERAL AVIATION HAZARDS TODAY. EXPECT TWO MAIN ROUNDS OF
SHOWERS AND THUNDERSTORMS TODAY. THE FIRST HAS ALREADY BEGUN AND
WILL CONTINUE THROUGH THE EARLY EVENING. CYS HAS THE HIGHEST
PROBABILITY FOR IMPACTS, FOLLOWED BY LAR AND SNY WITH THIS
ROUND. COULD SEE A FEW MAKING IT TO BFF AND RWL, BUT CONFIDENCE
IS LOWER THERE. THE PRIMARY HAZARD WILL BE VERY HEAVY RAINFALL
PRODUCING IFR TO LIFR VIS, BUT THERE IS ALSO THE POSSIBILITY FOR
FREQUENT LIGHTNING, GUSTY WINDS, AND SMALL HAIL. MOST LIKELY,
THIS ROUND WILL STRUGGLE IN THE CENTRAL AND NORTHERN PANHANDLE,
SO THE FORECAST BACKED OFF FOR IFR CONDITIONS IN BFF, AIA, AND
CDR.
A SECOND ROUND OF SHOWERS AND THUNDERSTORMS WILL KICK UP AROUND
SUNDOWN AND MOVE EAST THROUGH THE OVERNIGHT PERIOD. THIS ROUND
IS MORE LIKELY TO MAKE IT INTO THE NEBRASKA PANHANDLE, SO PROB30
GROUPS WERE MAINTAINED FOR THIS POTENTIAL. THE HAZARDS WILL BE
THE SAME AS THE FIRST ROUND.
LOW CLOUDS AND FOG WILL STILL BE A CONCERN THROUGHOUT THE
PERIOD, BUT OVERALL CONFIDENCE IS VERY LOW AS MODELS HAVE HAD A
POOR HANDLE ON THIS SO FAR TODAY. BE ALERT FOR POSSIBLE AMDS
THROUGH THE AFTERNOON AND EVENING AS CONFIDENCE INCREASES IN
TIMING AND LOCATION OF STORMS, LOW CLOUDS, AND FOG. EXPECT
CONDITIONS TO TREND TOWARDS VFR BETWEEN 14Z AND 17Z FRIDAY
MORNING AS DRIER AIR MOVES INTO THE AREA AND WINDS TURN MORE
WESTERLY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...FLOOD WATCH FROM 3 PM THIS AFTERNOON TO 10 PM MDT THIS EVENING
FOR WYZ117>119.
NE...FLOOD WATCH FROM 3 PM THIS AFTERNOON TO 10 PM MDT THIS EVENING
FOR NEZ003-019>021-054-055.
SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...MN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page