Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 240447
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1047 PM MDT WED JUL 23 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 300 PM MDT WED JUL 23 2014

SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE MOUNTAINS THIS
AFTERNOON AS EXPECTED. NOW THE QUESTION IS HOW FAR EAST WILL THE
STORMS MAKE IT. LOW CLOUDS THIS MORNING HAVE CUT MUCH OF THE
HEATING...AND A STORM COMPLEX EAST OF THE FORECAST AREA SET DOWN A
STABLE LAYER OF AIR. SPC MESOANALYSIS SHOWING 75 TO 100 J/KG OF
CONVECTIVE INHIBITION IN PLACE EAST OF THE LARAMIE RANGE...SO
SHOULD SEE STORM STRUGGLE TO MOVE OFF THE HIGHER TERRAIN FOR AT
LEAST THE NEXT HOUR OR TWO. AFTER THAT NOT CERTAIN STORMS WILL
MAKE IT INTO THE PLAINS BUT THERE IS POTENTIAL WITH ABUNDANT LOW
LEVEL MOISTURE AND SURFACE BASED CAPE 3500-4000 J/KG. SHOULD STORMS
ROOT INTO THE BOUNDARY LAYER IN THE PLAINS...THEN THEY COULD
EASILY BECOME SEVERE. THE GREATEST THREAT IS INTO EAST CENTRAL
WYOMING WHERE THE MID AND UPPER LEVEL WESTERLY WINDS ARE STRONGER.
WILL CERTAINLY HAVE TO KEEP AN EYE ON THINGS THIS AFTERNOON AND
EARLY EVENING.

ALREADY GETTING CONCERNED TOMORROW FORECAST IS TOO AGGRESSIVE ON
TEMPERATURES. LOOKING AT THE LATEST MODEL DATA THERE MAY BE
EXTENSIVE MID AND HIGH LEVEL CLOUDS AROUND AS MONSOON MOISTURE
MOVES ACROSS THE TOP OF THE UPPER LEVEL RIDGE. MODELS ALSO SHOWING
EMBEDDED SHORTWAVE ENERGY TOO. SHOULD THAT OCCUR THEN TEMPERATURES
COULD EASILY BE 5 DEGREES COOLER ALONG WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS. SEVERE THUNDERSTORMS ARE NOT EXPECTED
FOR THURSDAY.

A FRONTAL BOUNDARY IS FORECAST TO BRING IN A SHOT OF COOLER AIR
THURSDAY NIGHT. MODELS VARY GREATLY AS TO HOW COOL THE AIR WILL
BE. THE NAM IS VERY AGGRESSIVE AND WOULD GENERALLY HOLD
HIGH TEMPERATURES TO THE 80S FOR FRIDAY. THE GFS SHOWS LESS COOL
AIR AND A FAST REBOUND OF WARM AIR ALOFT FRIDAY AFTERNOON WHICH
WOULD PUSH HIGHS MAINLY INTO THE 90S. EITHER WAY THE MAIN CHANCE
FOR THUNDERSTORMS FRIDAY WILL BE OVER THE MOUNTAINS WITH DRY AIR
IN PLACE ACROSS THE FORECAST AREA.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 300 PM MDT WED JUL 23 2014

ZONAL FLOW INITIALLY OVER THE CWA SATURDAY WILL BECOME
INCREASINGLY NWLY SUNDAY AS THE UPPER HIGH RE-AMPLIFIES OVER THE
ROCKY MTN REGION...WITH THE RIDGE AXIS SLIGHTLY RETROGRADING
WESTWARD DURING THE WEEK. THE NWLY FLOW WILL ALLOW FOR A SFC HIGH
TO SETTLE SOUTH ACROSS THE PLAINS SUNDAY AND MOVE LITTLE THROUGH
THE MID PART OF NEXT WEEK WITH THE CWA RESIDING ON THE WESTERN
SIDE OF THIS COOLER AIR MASS. THIS WILL TAKE THE EDGE OFF THE
RECENT WARMTH WITH TEMPS BEING CLOSER TO SEASONAL AVERAGES
ESPECIALLY OVER THE PLAINS. MAINLY DRY WEATHER IS EXPECTED
SATURDAY AND SUNDAY THEN CONVECTION SHOULD INCREASE SOMEWHAT
MONDAY THROUGH WEDS AS MOISTURE INCREASES OVER THE REGION FROM THE
SOUTH AND WEAK IMPULSES MOVE ACROSS THE AREA ON THE FRONT SIDE OF
THE UPPER HIGH.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING)
ISSUED AT 1040 PM MDT WED JUL 23 2014

VFR CONDITIONS THROUGH THE TAF PERIOD. ISOLATED SHOWERS WILL BE
POSSIBLE AT CDR OVER THE NEXT FEW HOURS. A LLJ WILL ALSO RESULT IN
SOUTHERLY WIND GUSTS TO 30 KTS AT CDR THROUGH AROUND 10Z.
SOUTHWEST WINDS WILL INCREASE BY LATE THURS MORNING WITH
OCCASIONAL GUSTS TO 25-30 KTS THROUGH THE AFTERNOON ACROSS
SOUTHEAST WY. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP DURING THE AFTERNOON WITH GUSTY WINDS THE MAIN THREAT.

&&

.FIRE WEATHER...
ISSUED AT 300 PM MDT WED JUL 23 2014

ISOLATED THUNDERSTORMS OVER THE HIGHER ELEVATIONS OF SOUTHEAST WYOMING
MAY SPREAD INTO THE PLAINS THIS EVENING. FIRE WEATHER WATCH REMAINS IN
EFFECT FOR ZONE 301 IN EAST CENTRAL WYOMING FOR THURSDAY AFTERNOON.
MARGINAL RED FLAG CONDITIONS EXPECTED DEPENDING ON CLOUD COVER. MID AND
HIGH CLOUDS COULD INHIBIT WARMER TEMPERATURES AND REDUCE WIND SPEEDS AND
RELATIVE HUMIDITY BELOW CRITICAL LEVELS. ISOLATED SHOWERS AND
THUNDERSTORMS EXPECTED AGAIN THURSDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FIRE WEATHER WATCH FROM 9 AM MDT THURSDAY THROUGH THURSDAY
     AFTERNOON FOR WYZ301.

NE...NONE.
&&

$$

SHORT TERM...SML
LONG TERM...RE
AVIATION...FINCH
FIRE WEATHER...SML



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