349
FXUS65 KCYS 150758
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
158 AM MDT SAT AUG 15 2026
KEY MESSAGES
- ANOTHER ROUND OF THUNDERSTORMS WILL BRING THE POTENTIAL FOR
LOCALIZED FLASH FLOODING AND ISOLATED STRONG TO SEVERE
THUNDERSTORMS THIS AFTERNOON AND EVENING. A FLOOD WATCH IS IN
EFFECT FROM 2PM THROUGH 10PM THIS EVENING.
- UNSETTLED WEATHER CONTINUES THROUGH AT LEAST SUNDAY, BRINGING
COOLER THAN AVERAGE TEMPERATURES AND DAILY CHANCES FOR SHOWERS
AND THUNDERSTORMS.
- ISOLATED STRONG TO SEVERE STORMS AND LOCALIZED FLASH FLOODING
WILL REMAIN POSSIBLE SUNDAY.
- DRIER WEATHER AND TEMPERATURES CLOSE TO SEASONAL AVERAGES WILL
RETURN EARLY NEXT WEEK.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 157 AM MDT SAT AUG 15 2026
MONSOONAL MOISTURE CONTINUES TO ADVECT INTO THE REGION AGAIN TODAY
WITH ANOTHER ROUND OF SLOW MOVING, HEAVY RAIN PRODUCING
THUNDERSTORMS THIS AFTERNOON AND EVENING. UPPER-LEVEL SOUTHERLY TO
SOUTHWESTERLY FLOW WILL CONTINUE TO ADVECT MONSOONAL MOISTURE INTO
THE REGION ALL DAY SATURDAY WITH MULTIPLE 500MB VORTICITY MAXIMA
EJECTING ACROSS THE REGION. 700MB FLOW REMAINS LARGELY BENIGN TODAY,
WITH GENERALLY WESTERLY TO SOUTHWESTERLY FLOW EXPECTED. A MESSY,
SURFACE HIGH PRESSURE SYSTEM WILL ATTEMPT TO DEVELOP WEST OF THE
ROCKY MOUNTAINS OVER WESTERN COLORADO BEFORE STRENGTHENING INTO THE
AFTERNOON HOURS. SURFACE FLOW WILL LARGELY REMAIN WESTERLY TO
SOUTHWESTERLY AS THE HIGH PRESSURE REMAINS WEAK AND MESSY, BUT FLOW
IS EXPECTED TO FLIP TO THE EAST, ALONG AND EAST OF THE LARAMIE
RANGE, BY THE EARLY AFTERNOON HOURS AND CONTINUE THROUGH MUCH OF THE
EVENING HOURS. WITH AMPLE MOISTURE AVAILABLE DUE TO CONTINUED
MONSOONAL MOISTURE ADVECTION, THE EASTERLY FLOW WILL LEAD TO VERY
MOIST, UPSLOPE FLOW ALONG AND EAST OF THE LARAMIE RANGE. COMBINED
WITH THE SURFACE UPSLOPE AND 500MB VORTICITY MAXIMA, WEAK 700MB WARM
AIR ADVECTION DEVELOPS INTO LATER-AFTERNOON HOURS. THIS WILL ADD
ANOTHER MECHANISM TO GET FORCING ACROSS THE REGION. HEAVY RAINFALL
IS ANTICIPATED ONCE AGAIN TODAY, WITH THE WEATHER PREDICTION CENTER
PLACING PORTIONS OF THE REGION IN A SLIGHT RISK OF EXCESSIVE
RAINFALL AND A LARGER PORTION IN A MARGINAL RISK OF EXCESSIVE
RAINFALL. THEREFORE, LOCALIZED FLOODING WILL BE POSSIBLE TODAY WITH
ANOTHER ROUND OF SLOW MOVING THUNDERSTORMS. A FLOOD WATCH HAS BEEN
ISSUED FROM 2PM THROUGH 10PM THIS AFTERNOON AND EVENING FOR NEARLY
ALL LOCATIONS ALONG AND EAST OF THE LARAMIE RANGE, WHERE
PRECIPITABLE WATER VALUES REMAIN AT AND ABOVE THE 90TH PERCENTILE
AND MOIST, UPSLOPE FLOW PERSISTS. IN ADDITION TO THE FLOODING RISK
TODAY, THE STORM PREDICTION CENTER HAS PLACED FAR SOUTHEAST WYOMING
AND WESTERN NEBRASKA IN A SLIGHT RISK (LEVEL 2 OF 5) OF SEVERE
WEATHER THIS AFTERNOON. PRIMARY HAZARDS LOOK TO BE ISOLATED, LARGE
HAIL AND DAMAGING WIND GUSTS. ISOLATED POCKETS OF MLCAPE AND SBCAPE
AROUND 1000 J/KG WILL PROVIDE ENOUGH INSTABILITY FOR STRONGER
UPDRAFTS TO DEVELOP THIS AFTERNOON, ESPECIALLY ACROSS WESTERN
NEBRASKA. THE BIGGEST QUESTION WILL BE WHETHER OR NOT THE EARLY
MORNING CLOUD COVER ANTICIPATED ACROSS THE REGION PUTS A DAMPER ON
THE SEVERE POTENTIAL THIS AFTERNOON. POCKETS OF CLEARING SKIES WILL
BE POSSIBLE THIS MORNING, ESPECIALLY IN THE SOUTHERN PANHANDLE, BUT
CLOUDS WILL REMAIN OVER MUCH OF THE REGION DUE TO THE EXCESS
MOISTURE PRESENT THROUGHOUT THE ATMOSPHERE.
SLIGHTLY DRIER CONDITIONS WILL START TO TRY TO RETURN TO THE REGION
ON SUNDAY AS UPPER-LEVEL FLOW TURNS MORE WESTERLY, RATHER THAN
SOUTHWESTERLY, CUTTING OFF SOME OF THE MONSOONAL MOISTURE ADVECTION
INTO THE AREA. UPPER-LEVEL ZONAL FLOW IS EXPECTED TO DEVELOP BY
SUNDAY AFTERNOON, WHICH SHOULD START TO DRY OUT THE ATMOSPHERE.
HOWEVER, WITH THE AMPLE MOISTURE PRESENT OVER THE PAST SEVERAL DAYS,
PLENTY OF RESIDUAL MOISTURE WILL BE PRESENT TO GET ANOTHER ROUND OF
SHOWERS AND STORMS SUNDAY AFTERNOON INTO THE EVENING HOURS. A FEW
500MB VORTICITY MAXIMA WILL ADVECT ACROSS THE REGION SUNDAY
AFTERNOON, PROVIDING SOME FORCING FOR ASCENT. SLIGHTLY STRONGER
700MB WARM AIR ADVECTION BRIEFLY DEVELOPS SUNDAY AFTERNOON, ADDING
AN ADDITIONAL FORCING FOR ASCENT FOR SHOWERS AND STORMS. SURFACE
FLOW TURNS SOUTHERLY SUNDAY AFTERNOON THROUGH MUCH OF THE OVERNIGHT
HOURS, LEADING TO WEAK ASCENT ACROSS THE CHEYENNE RIDGE, LIKELY
RESULTING IN SHOWERS AND STORMS DEVELOPING IN THIS AREA ONCE AGAIN.
PRECIPITABLE WATER VALUES LOOK TO RETURN TOWARDS MORE
CLIMATOLOGICALLY AVERAGE VALUES SUNDAY, DECREASING THE THREAT FOR
ISOLATED FLOODING ACROSS THE REGION. HOWEVER, WITH MONSOONAL
MOISTURE STILL IN PLAY, FLOODING POTENTIAL CONTINUES FOR SUNDAY WITH
ANOTHER SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE WEATHER
PREDICTION CENTER. ANOTHER ROUND OF STRONG TO SEVERE STORMS WILL BE
POSSIBLE SUNDAY, WITH A MARGINAL RISK OF SEVERE WEATHER FOR MUCH OF
THE AREA AND A SMALL PORTION OF THE REGION UNDER A SLIGHT RISK OF
SEVERE WEATHER ONCE AGAIN.
LONG TERM /MONDAY THROUGH FRIDAY/
ISSUED AT 157 AM MDT SAT AUG 15 2026
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 NEAR 17C AT 700 MB.
TUESDAY...BRISK NORTHWEST FLOW ALOFT PREVAILS, AND WITH A DECENT
AMOUNT OF LOW AND MID LEVEL MOISTURE AVAILABILITY AS SEEN IN THE 12Z
GFS RUN, EXPECT ISOLATED TO WIDELY SCATTERED LATE DAY SHOWERS AND
THUNDERSTORMS, MAINLY EAST OF INTERSTATE 25 AND THE LARAMIE RANGE
DURING THE AFTERNOON, WITH COVERAGE EVERYWHERE IN THE EVENING.
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 THE
DAKOTAS INTO WESTERN MINNESOTA BY EVENING, WITH A MUCH COOLER
AIRMASS MOVING SOUTHWARD ACROSS THE NORTHERN ROCKIES, AS WELL AS THE
NORTHERN AND CENTRAL GREAT PLAINS, INCLUDING THE DAKOTAS AND MUCH OF
NEBRASKA BEHIND A COLD FRONT. MAXIMUM TEMPERATURES FOR OUR NECK OF
THE WOODS WILL BE QUITE COMFORTABLE WITH READINGS IN THE MID 70S TO
LOWER 80S, PERHAPS EVEN COOLER THAN THIS IF THE CANADIAN COOL SURGE
LIES FURTHER WEST. FROM EXPERIENCE, AND FROM THE MODEL TRENDS, THIS
TYPE OF COLD FRONTAL PASSAGE IS TYPICALLY MOSTLY DRY FOR OUR
FORECAST AREA, AND FOR CONSISTENCY SAKE, AND MATCHING UP WITH OUR
NEIGHBORING OFFICES, WE WILL CONTINUE WITH SCATTERED SHOWERS AND
THUNDERSTORMS IN THE AFTERNOON AND EVENING FOR NOW, THOUGH SUSPECT
THAT LATER SHIFTS WILL SEE FAR LESS POPS AS MODELS COME TO MORE
CONGRUENCY AND CONSISTENCY.
THURSDAY-FRIDAY...MODELS SUGGEST A RETURN TO BONE DRY AND HOTTER
CONDITIONS AS THE RIDGE ALOFT TRANSITIONS ACROSS THE NORTHERN AND
CENTRAL ROCKIES AND OUR COUNTIES. 700 MB TEMPERATURES RISE FROM NEAR
14C AT 00Z/FRIDAY TO 18Z AT 00Z/SATURDAY YIELDING MAXIMUM
TEMPERATURES MAINLY IN THE 80S FOR THURSDAY, WITH SOME 5 TO 10
DEGREES OF WARMING FOR FRIDAY. ANOTHER HOT AND DRY PERIOD,
STRETCHING INTO THE WEEKEND,IS ON TAP.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1111 PM MDT FRI AUG 14 2026
AFTER SHOWERS AND THUNDERSTORMS THIS PAST AFTERNOON/EVENING THAT
HAVE EXITED THE CWA, EXPECT A RELATIVELY CALM NIGHT WITH VIS
REDUCTIONS AS THE ONLY AVIATION HAZARD WHICH MAY AFFECT ALL THE
NEBRASKA PANHANDLE TERMINALS. THIS VIS REDUCTION SHOULD START AROUND
07Z TONIGHT THROUGH ABOUT 15Z SATURDAY. THEREAFTER EXPECT A RETURN
OF VFR CONDITIONS, ALBEIT BRIEFLY. ADDITIONAL ROUNDS OF SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ONCE AGAIN, SO PROB30 GROUPS HAVE BEEN
ADDED TO ACCOUNT FOR THIS, WITH KLAR, KRWL, AND KCDR HAVING THE
LEAST CHANCE AND KEPT THE MENTION OUT AT THIS TIME.
CYS WATCHES/WARNINGS/ADVISORIES
WY...FLOOD WATCH FROM THIS AFTERNOON THROUGH THIS EVENING FOR
WYZ102-107-108-117>119.
NE...FLOOD WATCH FROM THIS AFTERNOON THROUGH THIS EVENING FOR
NEZ002-003-019>021-054-055-095-096.
SHORT TERM...AM
LONG TERM...RUBIN/AM
AVIATION...RZ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page