Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 211700
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1100 AM MDT MON JUL 21 2014

.UPDATE...
ISSUED AT 1050 AM MDT MON JUL 21 2014

12Z MESO AND HIGH-RESOLUTION MODELS POINT TO AT LEAST THE
POSSIBILITY OF A FEW SHOWERS AND PERHAPS A WEAK THUNDERSTORM
DEVELOPING EAST OF THE LARAMIE RANGE DURING THE AFTERNOON HOURS.
THE DRY SUB-CLOUD LAYER WILL BE AN INHIBITING FACTOR...ALTHOUGH
SOME CU WAS ALREADY BEGINNING TO DEVELOP NR THE SNOWY/SIERRA MADRE
RANGES LATE THIS MORNING. AM NOT CONFIDENT IN MUCH IN THE WAY OF
RAIN WILL FALL WITH THIS SHOWER/WK THUNDERSTORM ACTIVITY...
ESPECIALLY GIVEN THE INTENSE HEAT AND RESULTANT INVERTED-V
SOUNDINGS. HOWEVER WIND GUSTS TO 40 MPH WILL BE POSSIBLE IN AND
AROUND AT CONVECTIVE ACTIVITY. SO...DID ADD THE MENTION TO THE
FORECAST. OTHERWISE AN EXTREMELY HOT DAY FOR MOST AREAS...WITH
CHADRON ALREADY 98 DEGREES AT 11 AM.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 200 AM AM MDT MON JUL 21 2014

HOT TEMPERATURES TO CONTINUE IN THE SHORT TERM. TEMPERATURES AND
PRECIP CHANCES ARE THE FORECAST CHALLENGES.

CURRENTLY...1020MB SURFACE HIGH OVER COLORADO AND WESTERN WYOMING
THIS MORNING. WATER VAPOR IMAGERY SHOWING SOME MONSOONAL MOISTURE
STREAMING NORTH FROM ARIZONA INTO WESTERN NEBRASKA. WYOMING IN THE
DRY SLOT THIS MORNING. PACIFIC SHORTWAVE ALSO SEEN ON WATER VAPOR
IMAGERY OVER NORTHERN NEVADA.

SHORTWAVE IS FORECAST TO TRACK NORTH INTO MONTANA THROUGH THE DAY
TODAY. BEING IN THE DRY SLOT...MOST OF WYOMING SHOULD STAY DRY
TODAY. MODELS DO HINT AT SOME LIGHT PRECIP OVER NORTHERN WYOMING
THAT COULD REACH DOWN INTO NORTHERN CONVERSE AND NIOBRARA COUNTIES
THIS AFTERNOON. MAINTAINED SOME SLIGHT CHANCE POPS FOR THESE AREA
AND POSSIBLY THE NORTHERN PANHANDLE...AS WELL AS THE SNOWY AND
SIERRA MADRE RANGES.

TEMPERATURES ARE THE BIG NEWS TODAY AS BOTH THE GFS AND ECMWF
MAINTAIN +18C 700MB TEMPERATURES OVER SOUTHERN WYOMING TODAY.
BELIEVE AFTERNOON HIGHS ARE GOING TO BE SIMILAR TO SUNDAYS HIGHS
WITH 100+ HIGHS IN THE PANHANDLE AND LOW TO MID 90S IN SOUTHEAST
WYOMING. NAM SOUNDINGS SHOWING AREAS OUT WEST MIXING UP TO 500MBS
TODAY...SO WINDY CONDITIONS OUT THAT WAY TODAY AS WINDS AT THAT
LEVEL IN EXCESS OF 30KTS. WILL MAINTAIN THE RED FLAG WARNINGS WE HAVE
OUT FOR ZONES THAT HAVE FUELS REPORTED CRITICAL.

700MB TEMPERATURES BEGIN TO COOL SOME TONIGHT AS RIDGE FLATTENS
OUT WITH THE SHORTWAVE MOVING INTO MONTANA. BY TUESDAY
MORNING...THE GFS SHOWS +12 TO +14C TEMPERATURES OVER SOUTHEAST
WYOMING. WINDS SHIFT NORTHEASTERLY TUESDAY AFTERNOON...SO WE
SHOULD SEE SOME RELIEF IN THE HOT TEMPERATURES AND FIRE WEATHER
CONDITIONS...AT LEAST TEMPORARILY. AREAS EAST OF THE LARAMIE RANGE
SHOULD SEE SOME INCREASED CHANCES FOR SHOWERS WEDNESDAY. BOTH THE
GFS AND ECMWF SHOW CONVECTION DEVELOPING WEDNESDAY AFTERNOON. BEST
CHANCES WILL BE OUT IN THE PANHANDLE.

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 310 AM MDT MON JUL 21 2014

STRONG UPPER LEVEL HIGH WILL REMAIN NEARLY STATIONARY NEAR THE
FOUR CORNERS REGION THROUGH NEXT WEEKEND. MONSOON MOISTURE WILL BE
IN THE GENERAL AREA. THEREFORE...AFTERNOON SHOWERS AND TSTORMS ARE
POSSIBLE EACH DAY. HOWEVER...THE PRESENCE OF THE UPPER LEVEL HIGH
WILL REDUCE MID TO UPPER LEVEL LAPSE RATES AND PREVENT ANYTHING
GREATER THAN ISOLATED COVERAGE ON MOST DAYS. KEPT POP AROUND 20
PERCENT EACH DAY...MAINLY EAST OF THE LARAMIE RANGE. HIGH
TEMPERATURES WILL REMAIN HOT...AND IN THE 90S TO AROUND 100
DEGREES OVER WESTERN NEBRASKA ON THURSDAY. TEMPS WILL LOWER A FEW
DEGREES ON FRIDAY AND SATURDAY AS A WEAK COOL FRONT MOVES ACROSS
THE AREA. THIS WILL ALLOW SOME OF THE MONSOON MOISTURE TO BE
PUSHED SOUTHWARD INTO COLORADO FOR THE WEEKEND. KEPT A SLIGHT
CHANCE OF TSTORMS IN THE FORECAST FOR NOW...MAINLY SOUTH. BUT
WOULD NOT BE SURPRISED IF THIS MENTION OF THUNDER FOR NEXT WEEKEND
IS REMOVED SOON DUE TO THE MORE STABLE POST-FRONTAL ENVIRONMENT
SHOWN ON THE GEM AND GFS. HIGH TEMPERATURES WILL RETURN TO NEAR
NORMAL LEVELS FOR THIS TIME OF THE YEAR BY SUNDAY. FURTHER OUT...A
GREATER COVERAGE OF SHOWERS AND TSTORMS ARE POSSIBLE BY THE LAST
WEEK OF JULY AS MONSOON MOISTURE RETURNS TO THE REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)

VFR CONDITIONS FOR MOST AREAS. FEW TO SCT HIGH-BASED CUMULUS CLOUDS
WILL DEVELOP OVER MUCH OF SOUTHEAST WY AND THE WESTERN NE PANHANDLE
THIS AFTERNOON. AN ISOLATED SHOWER OR WEAK THUNDERSTORM CANNOT BE
RULED OUT ALONG AND EAST OF THE LARAMIE RANGE AFTER 18Z. ERRATIC
WIND GUSTS TO 40 KTS AND OCCASIONAL LIGHTNING WILL BE THE MAIN
HAZARD FROM THIS ACTIVITY. CYS IS THE MOST LIKELY TERMINAL TO
EXPERIENCE THIS. OUTSIDE OF THUNDERSTORMS...GUSTY WEST WINDS WILL
PERSIST THROUGH EARLY EVENING WITH WINDS BEGINNING TO DIMINISH
AROUND SUNSET.

&&

.FIRE WEATHER...
ISSUED AT 200 AM MDT MON JUL 21 2014

RED FLAG WARNINGS IN EFFECT FOR 301...302 AND 306 TODAY FOR LOW
HUMIDITIES AND GUSTY WINDS. FORECAST SOUNDINGS SHOWING MOST AREAS
MIXING UP TO 18K FEET/500MBS...SO WINDS AT THAT LEVEL WILL BE
MIXED DOWN TO GROUND LEVEL THIS AFTERNOON. WE GET SOME RELIEF IN
WINDS AND HOT TEMPERATURES TUESDAY AS A BACKDOOR COLD FRONT MOVES
INTO THE NEBRASKA PANHANDLE AND EAST OF THE LARAMIE RANGE. SHOWERS
AND THUNDERSTORMS DEVELOP WEDNESDAY AFTERNOON AS NORTHEAST WINDS
POOL SOME LOW LEVEL MOISTURE INTO THE PANHANDLE. HOT TEMPERATURES
RETURN THURSDAY WITH TEMPERATURES SOARING INTO THE 90S ACROSS
SOUTHEAST WYOMING AND ABOVE 100 DEGREES IN THE PANHANDLE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR WYZ301-302-306.

NE...NONE.
&&

$$

UPDATE...HAHN
SHORT TERM...CLAYCOMB
LONG TERM...TJT
AVIATION...HAMMER
FIRE WEATHER...CLAYCOMB






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