230
FXUS65 KCYS 081927
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
127 PM MDT WED JUL 8 2026
KEY MESSAGES
- SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND THURSDAY
WITH HEAVY RAINFALL, HAIL, AND STRONG GUSTY WINDS POSSIBLE.
- A RIDGE BUILDS INTO THE LONG TERM, DRYING THE AREA OUT AND
DEVELOPING RED FLAG AND POTENTIAL HEAT ADVISORY CONDITIONS
THROUGH NEXT WEEK.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 125 PM MDT WED JUL 8 2026
AS OF THIS AFTERNOON THE DRYLINE IS NOTED ON RADAR RIGHT AROUND
THE I-25 CORRIDOR AND RETREATING WESTWARDS INTO CHEYENNE PROPER.
DEVELOPMENT HAS BEGUN ALONG THIS BOUNDARY WITH A FEW STORMS
NOTED, BUT NOTHING STRONG CURRENTLY. FORECAST SOUNDING PROFILES
ACROSS THE REGION NOTE INVERTED V'S, WHICH COMBINED WITH DCAPE
VALUES INTO THE 1000-1500 J/KG RANGE WOULD BE INDICATIVE OF
HIGH BASED STORMS WITH STRONG WIND GUSTS THE PRIMARY HAZARDS.
THAT BEING SAID, THERE IS A LITTLE BIT OF INSTABILITY ACROSS THE
REGION, AND SOME MEAGER SUPPORT FOR UPDRAFTS, SO WE CAN'T RULE
OUT A STORM OR TWO TO HAVE AT LEAST SOME HAIL, WHETHER IT BE
SEVERE IN SIZE OR SMALL ACCUMULATING HAIL. FINALLY, MOISTURE IS
ACTUALLY NOTABLY PLENTIFUL EAST OF I-25 DESPITE THE DRY SURFACE,
WITH PWAT VALUES INTO THE 1-1.5" RANGE. WITH THE SCATTERED
NATURE OF STORM DEVELOPMENT, IF ANY WE GET MULTIPLE STRONGER
STORMS TRAINING OVER THE SAME LOCATION, A MARGINAL RISK OF
EXCESSIVE RAINFALL WILL BE POSSIBLE. STORMS WILL CONTINUE INTO
THE EARLY EVENING, BUT BY AROUND 8-9 PM STORMS SHOULD BE ON THE
DECLINE AS SUPPORT WANES.
MOVING INTO THURSDAY, OUR SEVERE RISK CONTINUES ONCE AGAIN ALONG
AND EAST OF THE I-25 CORRIDOR, BUT THIS TIME PROFILES WILL
SUPPORT A BIT MORE ORGANIZATION TO STORM DEVELOPMENT. INITIAL
STORMS SHOULD GO UP DURING THE EARLY AFTERNOON WITH STEEP MID-
LEVEL LAPSE RATES AND MODEST INSTABILITY AROUND 1000-2000 J/KG,
WHICH WOULD SUPPORT ISOLATED STORMS CAPABLE OF BOTH LARGE HAIL
AND DAMAGING WINDS. THIS BATCH OF ACTIVITY THOUGH WILL LIKELY
GROW UPSCALE INTO A MORE LINEAR FEATURE, WHICH WILL SHIFT THE
PRIMARY HAZARD INTO MOSTLY STRONG WINDS AS STORMS EVOLVE INTO
WESTERN NEBRASKA. AND LIKE TODAY, PWAT VALUES INTO THE 1-1.5"
RANGE SHOULD FUEL AT LEAST A MEAGER RISK OF LOCALIZED FLOODING.
ONCE AGAIN AS THE SUN GOES DOWN WE'LL SEE STORM ACTIVITY WANE
AND/OR MOVE OUT OF OUR AREA.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED AT 125 PM MDT WED JUL 8 2026
FRIDAY...THE ATMOSPHERE DRIES OUT SOMEWHAT COMPARED TO TODAY AND
THURSDAY, WITH SHORTWAVE RIDGING ALOFT BULGING OVER EASTERN WYOMING.
THE 12Z GFS INDICATES DECENT LOW AND MID LEVEL MOISTURE FOR FAR
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE, AND DIURNAL HEATING
AND LOW LEVEL MECHANICAL LIFT, ALONG WITH A PASSING PERTURBATION,
WILL LIKELY PRODUCE ISOLATED LATE DAY SHOWERS AND THUNDERSTORMS FROM
I-25 EASTWARD, AND WE MAY SEE OUR POPS AND THUNDERSTORM COVERAGE
INCREASE SOMEWHAT IN THE NEXT FEW MODEL RUNS AND DAYS.
SATURDAY THROUGH WEDNESDAY...RIDGING ALOFT DOMINATES OUR REGION,
WITH QUITE DRY AIR AT LOW AND MID LEVELS, ACCOMPANIED BY 700 MB
TEMPERATURES FROM 14 TO 21 CELSIUS, THUS CHANCES FOR LATE DAY
SHOWERS AND THUNDERSTORMS WILL BE NEARLY NIL AND NON EXISTENT, AND
DRY WEATHER WILL PREVAIL. THE 700 MB TEMPERATURES WILL YIELD MAXIMUM
TEMPERATURES IN THE 90 TO 105 DEGREE RANGE. A WEAK PERTURBATION AND
A SLIGHT INCREASE IN MID LEVEL MOISTURE MAY SPARK ISOLATED
THUNDERSTORMS ON TUESDAY, AND MORESO ON WEDNESDAY, ALONG THE
CONVECTIVE INHIBITION ALOFT GRADIENT ALONG THE I-25 CORRIDOR AND
FURTHER TO THE WEST.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1128 AM MDT WED JUL 8 2026
A RELATIVELY ACTIVE DAY FOR THUNDERSTORM DEVELOPMENT IS EXPECTED
THIS AFTERNOON AND EVENING, AS THE STORM PREDICTION CENTER IN
NORMAN, OKLAHOMA HAS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS
AFTERNOON AND EVENING, TO THE EAST OF A LUSK TO CHEYENNE LINE,
INCLUDING FAR SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE. A
MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THIS AFTERNOON EXISTS
ELSEWHERE TO THE WEST OF A LUSK TO CHEYENNE LINE.
SYNOPTICALLY, A NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT WILL
MOVE INTO WESTERN NEBRASKA THIS EVENING, WHILE A LOW LEVEL
CONVERGENCE AXIS DEVELOPS ALONG THE INTERSTATE 25 CORRIDOR, THEN
STORMS WILL DEVELOP AND STRENGTHEN AS THEY DEVELOP AND
PROPAGATE ACROSS FAR SOUTHEAST WYOMING, AND ESPECIALLY THE
NEBRASKA PANHANDLE, WHERE SCATTERED THUNDERSTORMS MAY
CONGLOMERATE AND DEVELOP INTO A MESOSCALE CONVECTIVE COMPLEX, OR
MCC, SOMEWHERE OVER THE NORTHERN OR CENTRAL NEBRASKA PANHANDLE
THIS EVENING, THUNDERSTORMS WILL LIKELY END ACROSS THE NEBRASKA
PANHANDLE IN THE 03Z TIMEFRAME.
WYOMING TAFS...USING THE 16Z HRRR, WHICH HAS CONSISTENTLY BEEN
FAIRLY ACCURATE WITH RESPECT TO TIMING, HIGH CONFIDENCE, AND EXPECT
THUNDERSTORM INITIATION BETWEEN 18Z AND 20Z FROM A DOUGLAS TO
LARAMIE LINE, WITH STORMS STRENGTHENING ALONG THE I-25 CORRIDOR
NEAR 22Z, AND MOSTLY MOVING INTO WESTERN NEBRASKA AROUND 00Z TO
02Z.
EXPECT TEMPO FOR THUNDERSTORMS AT RAWLINS AND LARAMIE FOR MUCH
OF THE AFTERNOON AND INTO THE EARLY EVENING HOURS, AND SOME
STORMS WILL PRODUCE LOW LEVEL TURBULENCE, STRONG DOWNDRAFTS, AS
WELL AS GUSTY AND ERRATIC WINDS UP TO 45 KNOTS, ALONG WITH BRIEF
MVFR VISIBILITY RESTRICTIONS. VFR PREVAILS HOWEVER, WITH CLOUDS
CLEARING OUT LATE THIS EVENING AND OVERNIGHT. AS IS TYPICAL,
EXPECT GUSTY GRADIENT AND MIX DOWN WINDS UNTIL SUNSET.
AT CHEYENNE, BEST CHANCE FOR THUNDERSTORMS, AND HIGH CONFIDENCE,
ACCORDING TO THE LIKELY ACCURATE 16Z RUN OF THE HRRR, WILL BE
FROM 20Z TO 02Z, WITH STORM INITIATION AROUND 20Z, AND STORMS
INCREASING IN COVERAGE AND INTENSITY FROM 22Z TO 01Z. SOME
STORMS WILL PRODUCE LOW LEVEL TURBULENCE, STRONG DOWNDRAFTS, AS
WELL AS GUSTY AND ERRATIC WINDS UP NEAR 50 KNOTS, ALONG WITH
BRIEF MVFR VISIBILITY RESTRICTIONS. VFR PREVAILS HOWEVER, WITH
CLOUDS CLEARING OUT LATE THIS EVENING AND OVERNIGHT. AS IS
TYPICAL, EXPECT GUSTY GRADIENT AND MIX DOWN WINDS UNTIL SUNSET.
NEBRASKA TAFS...HIGH CONFIDENCE IN THE 16Z HRRR RUN, WHICH HAS
CONSISTENTLY SHOWN THUNDERSTORMS DEVELOPING AND/OR PROPAGATING
ALONG THE WYOMING AND NEBRASKA STATE LINE AROUND 23Z, AND
CROSSING THE PANHANDLE DURING THE 00Z TO 03Z TIME FRAME, WITH
CLUSTERS OF THUNDERSTORMS AND A POSSIBLE MCC, MESOSCALE
CONVECTIVE COMPLEX, FORMING THIS EVENING, SOMEWHERE OVER THE
NORTHERN OR CENTRAL NEBRASKA PANHANDLE AND PROPAGATING
SOUTHEASTWARD. THE STRONGEST STORMS WILL BE CAPABLE OF
PRODUCING ONE INCH DIAMETER HAIL OR LARGER, WIND GUSTS IN EXCESS
OF 60 MPH AND LOCALLY HEAVY RAINFALL, ALONG WITH LOW LEVEL
TURBULENCE, AND STRONG DOWNDRAFTS. BRIEF MVFR WILL BE LIKELY
DURING THE THUNDERSTORMS THIS EVENING, WITH SKIES CLEARING OUT
LATE THIS EVENING AND LATE TONIGHT. AS IS TYPICAL, EXPECT GUSTY
GRADIENT WINDS AND MIX DOWN WINDS UNTIL SUNSET.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...RUBIN
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