231
FXUS65 KCYS 121825
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1225 PM MDT WED AUG 12 2026
KEY MESSAGES
- SLIGHT RISK OF SEVERE WEATHER WEDNESDAY AS MONSOONAL MOISTURE
FLOWS INTO THE REGION. SHOWERS AND THUNDERSTORMS CONTINUE ON
THURSDAY BUT SEVERE RISK WILL DECLINE AND MOVE SOUTHEAST.
- WARM AGAIN TODAY BUT COOLER THAN THE START OF THE WEEK, WITH
MUCH COOLER TEMPERATURES THROUGH THE WEEKEND.
- WARMING TREND EARLY NEXT WEEK MAY BRING US BACK TO NEAR NORMAL
LATE SUMMER WARMTH.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 230 AM MDT WED AUG 12 2026
MONSOONAL MOISTURE WILL NOW MOVE INTO THE REGION AS WE UNDERGO A
PATTERN CHANGE BRINGING DAILY CHANCES OF SHOWERS AND
THUNDERSTORMS FOR OUR ENTIRE CWA ALONGSIDE AN INITIAL RISK OF
SEVERE WEATHER, FOLLOWED BY AN INCREASED FLOODING RISK. THIS
MORNING THE UPPER LEVEL RIDGE THAT HAS BEEN CONTROLLING OUR
WEATHER PATTERN WILL BEGIN SHIFTING EASTWARDS, TURNING OUR FLOW
ALOFT TO SOUTHWESTERLY AND ALLOWING MUCH NEEDED MOISTURE TO
BEGIN INFILTRATING OUR AREA. AT THE SURFACE, A BACKDOOR COLD
FRONT WILL SLOWLY DESCEND ACROSS THE AREA THROUGH THE DAY,
ALLOWING FLOW BEHIND IT TO SHIFT TO SOUTHERLY TO SOUTHEASTERLY
AND AIDING IN MOISTURE RETURN AT THE SURFACE. THIS FRONT WILL
LEAD TO COOLER TEMPERATURES DURING THE LATER HALF OF THE WEEK
AND INTO THE WEEKEND, BUT FOR TODAY WE WILL GET ONE MORE ROUND
OF ABOVE NORMAL. WHILE NOT AS HOT AS THE PAST SEVERAL DAYS,
HIGHS WILL RANGE IN THE 80'S TO 90'S, WHICH IS AROUND 3-6
DEGREES ABOVE AVERAGE. MEANWHILE, STORM INITIATION IS EXPECTED
FROM BOTH THIS BOUNDARY AND UPSLOPE FLOW BEGINNING AS EARLY AS
LATE THIS MORNING AND CONTINUING INTO THE EVENING HOURS. STEEP
LAPSE RATES OF 8-10 C/KM ALONGSIDE MUCAPE OF 1000-1500 J/KG WEST
OF THE I-25 CORRIDOR AND SOME PATCHY BULK SHEAR IN THE
NEIGHBORHOOD OF 20-40 KNOTS COULD SUPPORT STRONGER INITIAL
SUPERCELLS OR CLUSTERS CAPABLE OF LARGE HAIL AND DAMAGING WIND
GUSTS. THE PROBLEM WILL BE THE CONTINUED USE OF THE ATMOSPHERE
AND NUMEROUS SHOWERS AND STORMS STREAMING INTO THE REGION
THROUGH THE AFTERNOON HOURS. THIS ACTIVITY WILL LIKELY USE UP
THESE FAVORABLE PARAMETERS AND BY THE EVENING HOURS EXPECTING
STORMS TO RELAX AND BECOME SUB-SEVERE AS WIDESPREAD RAINFALL
BECOMES THE DOMINANT CONCERN. PWAT VALUES WILL RISE
CONSIDERABLY, AND BY THIS EVENING WE'LL BE LOOKING AT VALUES
BETWEEN 1-1.6", ROUGHLY 150-175% OF NORMAL ON AVERAGE. THE NBM
PAINTS A 20-60% PROBABILITY OF 0.5"+ OF NEW RAINFALL, HEAVIEST
IN THE NEBRASKA PANHANDLE. NOW WHILE NOT AN ABSOLUTE SOAKER OF
A DAY, OUR INCREDIBLY DRY GROUND CAN PRESENT A CONCERN FOR
BEING HYDROPHOBIC, AND IF WE GET ANY TRAINING STORMS OF HEAVIER
DOWNPOURS FROM STRONGER ACTIVITY, THEN STORMS WILL HAVE A
MARGINAL RISK OF FLOODING.
MOVING INTO THURSDAY OUR RISK PRIMARILY SHIFTS FROM SEVERE
WEATHER TO FLOODING. WHILE NOT COMPLETELY GONE, OUR SEVERE RISK
WILL BE MOSTLY RELEGATED TO LARAMIE COUNTY THROUGH THE SOUTHERN
NEBRASKA PANHANDLE. CAMS DEVELOP A FRESH BATCH OF CONVECTION
DURING THE AFTERNOON INTO THE EARLY EVENING ACROSS THIS AREA
THAT COULD TAKE ADVANTAGE OF MODEST INSTABILITY AND DECENT WIND
SHEAR, CREATING ANOTHER RISK OF LARGE HAIL AND DAMAGING WIND
GUSTS FOR THE DAY. OTHERWISE, PRECIPITATION TOTALS SHOULD JUMP
UP NOTABLY TODAY AS MOISTURE HITS ITS PEAK FOR THIS EVENT. PWAT
VALUES ARE EXPECTED TO RISE TO 160-180% OF NORMAL BY THE
EVENING, WITH THE NBM UP TO A 25-50% PROBABILITY OF 1" OR MORE
OF NEW RAINFALL FOR THE DAY, THIS TIME HIGHEST ACROSS THE I-25
CORRIDOR SOUTH OF DOUGLAS. ONCE AGAIN ANY STRONGER STORMS OR
TRAINING RAINFALL ALONGSIDE GROUND THAT MAY BECOME SATURATED
COULD LEAD TO AN INCREASED FLOODING THREAT, WITH A SLIGHT RISK
OVERALL EXPECTED ACROSS OUR ENTIRE CWA. FINALLY, THE FIRST
NOTABLE COOLDOWN FROM THE SUMMER WILL OCCUR AS TEMPERATURES
BOTTOM OUT IN THE MID 70'S TO LOW 80'S FOR THE DAY THANKS TO THE
COLD FRONT AND WIDESPREAD CLOUD COVER.
FRIDAY HOWEVER WE MAY GET ENOUGH CLEARING EAST OF THE I-25
CORRIDOR THAT TEMPERATURES WILL JUMP UP JUST A TAD FOR THE DAY.
HIGHS ARE STILL EXPECTED TO SIT IN THE MID TO UPPER 70'S FOR OUR
WESTERN ZONES OUTSIDE OF THE MOUNTAINS, BUT WIDESPREAD LOW TO
UPPER 80'S SHOULD OCCUR EAST OF THE MOUNTAINS. BUT THAT'S NOT TO
SAY OUR PRECIPITATION CHANCES ARE DONE YET, AS ANOTHER ROUND OF
OF SHOWERS AND THUNDERSTORMS WILL OCCUR DURING THE AFTERNOON
AND INTO THE EVENING. PWAT VALUES DO DROP BACK DOWN TO AROUND
130-150% OF NORMAL, STILL HIGHER THAN NORMAL THOUGH, AND THIS
ACTIVITY COULD ONCE AGAIN FUEL A FLOODING RISK. WITH THE MOST
LIKELY AREA FOR STRONGER OR MULTIPLE ROUNDS OF STORMS BEING
LARAMIE COUNTY THROUGH THE SOUTHERN NEBRASKA PANHANDLE AGAIN, A
SLIGHT RISK FOR FLOODING IS YET AGAIN EXPECTED FOR THIS AREA,
WHILE A WIDESPREAD MARGINAL RISK ELSEWHERE IS ANTICIPATED. THE
BEST PARAMETERS FOR SEVERE ACTIVITY WILL ALSO DRIFT A BIT
FURTHER SOUTHEASTWARD FROM OUR AREA, ALLOWING A POTENTIAL
REPRIEVE FROM STRONGER ACTIVITY (THOUGH NEVER RULING IT OUT WITH
HOW THIS REGION LIKES TO OVER PERFORM!) OVERALL THOUGH WE'LL
FINALLY SEE BENEFICIAL MOISTURE, AND PRECIPITATION CHANCES
SHOULD LINGER INTO THE WEEKEND, HOPEFULLY MAKING AT LEAST A
SMALL DENT INTO THIS POTENT DROUGHT.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
ISSUED AT 103 PM MDT TUE AUG 11 2026
THURSDAY EVENING STARTS OFF THIS LONG TERM PERIOD WITH
MONSOONAL MOISTURE MOVING IN, AND A SHORTWAVE MOVING THROUGH THE
AREA. WITH PRECIPITABLE WATER VALUES IN THE 1-1.5 RANGE, RH
VALUES 60-90%, AND THE SHORTWAVE, ITS SAFE TO SAY OUR AREA WILL
BE GETTING SOME MUCH NEEDED MOISTURE. THIS MOISTURE STICKS
AROUND THROUGH MONDAY, BRINGING DAILY AFTERNOON CHANCES OF
PRECIPITATION. THIS PRECIPITATION LOOKS TO MAINLY BE SHOWERS,
BUT AN ISOLATED THUNDERSTORM CANNOT BE RULED OUT ESPECIALLY NEAR
THE NE PANHANDLE WITH CAPE VALUES NEAR 1000J/KG. WINDS DO NOT
APPEAR TO BE OUT OF THE ORDINARY, STAYING BELOW 15 KNOTS MOST OF
THE TIME. TEMPERATURES COOL OFF AS A COLD FRONT MOVES OVER THE
AREA THURSDAY. 700MB TEMPERATURES STAY NEAR 12C DURING THE
DAYTIME THURSDAY-SUNDAY, WITH NIGHTTIME TEMPERATURES GETTING
NEAR 10C. THIS MEANS TEMPERATURES WILL COOL OFF NEARLY 20F FROM
WHAT WE HAVE BEEN EXPERIENCING. TYPICALLY OUR AREA HAS DAYTIME
TEMPERATURES NEAR 83F THIS TIME OF YEAR. THIS IS A WELCOMED
BREAK FROM OUR HOT TEMPERATURES THE LAST FEW WEEKS. WITH ALL OF
THIS MONSOONAL MOISTURE COMING IN, FIRE WEATHER IS NOT A CONCERN
THROUGH THIS LONG TERM PERIOD.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1138 AM MDT WED AUG 12 2026
WEST SOUTHWEST FLOW ALOFT WILL CONTINUE, WHILE A SHORTWAVE
TROUGH ALOFT MOVES FROM NORTH CENTRAL WYOMING AT MIDDAY TO
NORTHWEST SOUTH DAKOTA THIS EVENING. MEANWHILE, AT THE SURFACE,
LOW PRESSURE WILL DEEPEN ACROSS EASTERN COLORADO WITH A FEW LOW
LEVEL CONVERGENCE AXISES DEVELOPING ACROSS SOUTHEAST WYOMING AND
WESTERN NEBRASKA. ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP ACROSS SOUTHEAST WYOMING THIS AFTERNOON AND DEVELOP AND
PROPAGATE EASTWARD ACROSS WESTERN NEBRASKA THIS EVENING. SOME OF
THE STORMS ACROSS THE EASTERN TIER OF SOUTHEAST WYOMING COUNTIES
AND THE NEBRASKA PANHANDLE, WILL BECOME STRONG TO SEVERE THIS
AFTERNOON AND EVENING.
WYOMING TAFS...INHERITED TAFS FROM OUR MIDNIGHT SHIFT FORECASTER
WERE IN GOOD SHAPE, WITH ONLY SOME MINOR TWEEKS NEEDED. BASED
ON THE 12Z NAM AND THE CONSISTENT RUNS OF THE HRRR, HIGH
CONFIDENCE IN ISOLATED TO SCATTERED THUNDERSTORMS DEVELOPING
MAINLY EAST OF A RAWLINS TO LUSK LINE THROUGH 21Z, WITH STORMS
INTENSIFYING FROM 21Z TO 00Z ALONG AND EAST OF A LUSK TO
CHEYENNE LINE, AND ENDING BY 01Z, BEFORE MORE ISOLATED TO
SCATTERED SHOWERS AND A FEW THUNDERSTORMS OCCUR THIS EVENING.
THUNDERSTORMS WILL PRODUCE ERRATIC WINDS AND GUSTS UP TO 40
KNOTS, WITH A FEW STORMS FROM LUSK TO CHEYENNE POSSIBLY SEEING
HIGHER WIND GUSTS. STORMS WILL PRODUCE OCCASIONAL MVFR,
OTHERWISE VFR PREVAILS. WIDESPREAD MVFR CEILINGS AND
VISIBILITIES DUE TO FOG WILL DEVELOP FROM 08Z TO 15Z ALONG AND
EAST OF INTERSTATE 25. TYPICALLY GUSTY DIURNAL WINDS TO NEAR 30
KNOTS WILL OCCUR UNTIL SUNSET.
NEBRASKA TAFS...INHERITED TAFS FROM OUR MIDNIGHT SHIFT
FORECASTER WERE IN DECENT SHAPE, THUS ONLY SOME MINOR TWEEKS
NEEDED. USING THE 12Z NAM AND THE CONSISTENT PAST FEW RUNS OF
THE HRRR, HIGH CONFIDENCE IN ISOLATED TO SCATTERED THUNDERSTORMS
DEVELOPING ALONG THE WYOMING-NEBRASKA STATE LINE AROUND 20-22Z
AND STRENGTHENING AND PROPAGATING EASTWARD ACROSS THE PANHANDLE
WELL INTO THE EVENING HOURS. SOME OF THE STORMS WILL BECOME
STRONG TO SEVERE THIS AFTERNOON AND EVENING, PRODUCING ERRATIC
WINDS GUSTING UP TO 45 KNOTS, WITH A FEW STORMS, MOST LIKELY
ACROSS THE NORTHERN PANHANDLE, PRODUCING WINDS GUSTS IN EXCESS
OF 50 KNOTS ALONG WITH SOME HAIL OF ONE INCH DIAMETER OR LARGER,
ALONG WITH LOCALLY HEAVY RAIN. THE STRONGEST STORMS WILL
PRODUCE LOCALIZED MVFR CEILINGS AND VISIBILITIES THIS EVENING.
WIDESPREAD IFR AND MVFR CEILINGS DUE TO LOW CLOUDS AND FOG WILL
FORM FROM ROUGHLY 06Z TO 15Z. TYPICALLY GUSTY DIURNAL WINDS TO
NEAR 25 KNOTS EXPECTED UNTIL SUNSET.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...CG
LONG TERM...ML
AVIATION...RUBIN
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