Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 170042
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
642 PM MDT SAT AUG 16 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 245 PM MDT SAT AUG 16 2014

A FEW SHOWERS AND STORMS HAVE FIRED THIS AFTERNOON OVER THE
CENTRAL NEB PANHANDLE ALONG A WEAK BOUNDARY. THESE SHOULD DIE OFF
LATE THIS AFTERNOON OR EARLY EVENING LEAVING MAINLY CLEAR SKIES
ACROSS THE CWA FOR OVERNIGHT INTO SUNDAY MORNING.

AN UPPER SHORTWAVE WILL PASS ACROSS MAINLY THE NORTHERN PLAINS
SUNDAY WITH A SFC TROF PROGRESSING EAST ACROSS THE PANHANDLE. THIS
WILL SET UP A WARM AND DRY DOWNSLOPE PATTERN ACROSS THE CWA SO
EXPECT MAINLY DRY WEATHER DURING THE DAY AS THE TROF SHOULD BE
EAST OF THE CWA BY EARLY AFTERNOON. A FEW BREEZY AREAS POSSIBLE
AROUND THE MOUNTAINS SUNDAY AFTERNOON. A WEAK SFC HIGH WILL THEN
BUILD SE ACROSS THE CWA SUNDAY NIGHT INTO MONDAY BRINGING A LITTLE
COOLER AIR. SFC UPSLOPE FLOW MONDAY MAY TRANSPORT ENOUGH MOISTURE
WESTWARD TO ALLOW FOR SOME ISOLATED CONVECTION MAINLY OVER THE
MTNS MONDAY AFTERNOON WITH ANY ACTIVITY THEN DISSIPATING EARLY IN
THE EVENING.

.LONG TERM...(TUESDAY THROUGH SATURDAY)
ISSUED AT 330 PM MDT SAT AUG 16 2014

GENERAL CONSENSUS WITH THE 12Z/18Z MEDIUM RANGE MODEL GUIDANCE LEADS
TO BETTER THAN AVERAGE FORECAST CONFIDENCE. BOTH THE GFS AND ECMWF
PROG THE NEXT SHORTWAVE TO TRACK NORTHEAST ACROSS NORTHERN CO AND
SOUTHERN WY TUESDAY THEN EAST INTO THE CENTRAL PLAINS TUESDAY NIGHT.
A WEAKER TRAILING SHORTWAVE LOOKS TO MOVE ACROSS SOUTHEAST WY ON
WEDNESDAY. SUBTROPICAL MOISTURE WITH THESE PASSING WAVES WILL NOT
BE AS ROBUST AS LAST WEEK WITH PRECIP WATER VALUES LESS THAN AN
INCH. CONSEQUIENTYLY...SHOWER/TSTORM COVERAGE WILL BE ISOLATED TO
WIDELY SCATTERED.

FOR THE LATTER HALF OF THE WEEK...A SERIES OF SHORTWAVES WILL CARVE
OUT A LONG WAVE TROUGH OVER THE INTERMOUNTAIN WEST. MEANWHILE...A
UPPER RIDGE WILL AMPLIFY OVER THE EASTERN GREAT PLAINS AND MIDWEST.
THE FLOW ALOFT WILL PREVAIL FROM THE SOUTHWEST. SHORTWAVE ENERGY
WILL DISPLACED WELL NORTH AND WEST OF THE CWA. DIURNAL CONVECTIVE
COVERAGE WILL BE ISOLATED AND CONFINED TO THE HIGHER TERRAIN OF
SOUTHEAST WY. FAVORED THE DRIER GFS OVER THE WETTER ECWMF WITH
POPS AND QPF. WITH SHORTWAVES PASSING WELL NORTH OF THE CWA...THIS
WILL ENHANCE THE MID LEVEL GRADIENTS TO GENERATE GUSTY SOUTHWEST
SURFACE WINDS ALONG AND WEST OF THE LARAMIE RANGE. THE COMBINATION
OF GUSTY WINDS AND LOW HUMIDITY WILL RAISE THE FIRE SPREAD
POTENTIAL THERE.

700MB TEMPERATURES WILL CHANGE LITTLE TUESDAY THROUGH FRIDAY...RANGING
FROM 12C TO 15C. THE RESULT WILL BE ABOVE SEASONAL NORMAL TEMPERATURES
WITH DAYTIME HIGHS 85 TO 95 LOWER ELEVATIONS WITH 60S AND 70S MOUNTAINS.
SLIGHTLY COOLER TEMPERATURES CAN BE EXPECTED SATURDAY...ESPECIALLY
OVER SOUTHEAST WY. NIGHTTIME LOWS WILL BE IN THE 50S TO AROUND 60
WITH 40S MOUNTAINS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY AFTERNOON)
ISSUED AT 640 PM MDT SAT AUG 16 2014

VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. SHALLOW CU
DEVELOPMENT WILL CONTINUE TO DISSIPATE THRU SUNSET. BREEZY WINDS
WILL BECOME LIGHT OVERNIGHT. MORE SHALLOW CU DEVELOPMENT EXPECTED
AGAIN ON SUNDAY...WITH BREEZES RETURNING BY 16-18Z.

&&

.FIRE WEATHER...
ISSUED AT 245 PM MDT SAT AUG 16 2014

MARGINAL FIRE WEATHER CONDITIONS OCCURRING OVER THE FAR WEST NOW
AND THIS SHOULD CONTINUE FOR A FEW MORE HOURS. CURRENT RED FLAG
WARNING LOOKS O.K. BUT SHOULD BE ABLE TO CANCEL EARLY THIS EVENING.

MORE WIDESPREAD CRITICAL CONDITIONS LOOKS A DECENT BET FOR SUNDAY
AFTERNOON AS SFC WINDS SHOULD BE A LITTLE STRONGER IN RESPONSE TO
A PASSING SHORTWAVE TO THE NORTH WITH DRIER AIR SPREADING FARTHER
EAST OVER THE PLAINS. AFTER THAT...LIGHTER WINDS EXPECTED EARLY
NEXT WEEK WITH A LITTLE MORE MOISTURE ALLEVIATING CONCERNS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING
     FOR WYZ301-303-304-306-308>310.

     RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR WYZ303-304.

NE...NONE.
&&

$$

SHORT TERM...RE
LONG TERM...JAMSKI
AVIATION...HAHN
FIRE WEATHER...RE





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