Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 242338
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
538 PM MDT MON AUG 24 2015

.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...
ISSUED AT 245 PM MDT MON AUG 24 2015

BROAD UPPER-LEVEL RIDGING EXTENDS ACROSS MUCH OF THE WESTERN/CENTRAL
CONUS THIS AFTERNOON. THE RESULTING LARGE SCALE SUBSIDENCE OVER THE
CENTRAL ROCKIES HAS GIVEN WAY TO GENERALLY WARM/DRY CONDITIONS WITH
HARDLY EVEN A CLOUD TO SPEAK OF ON VISIBLE SATELLITE. SOME TOWERING
CUMULUS OVER THE SIERRA MADRES COULD BECOME WEAK TSTMS...BUT EXPECT
THAT ACTIVITY TO STAY IN THE HIGH COUNTRY. A TRANQUIL PATTERN SHOULD
PERSIST THROUGH WED AS MID LEVEL HEIGHTS CONTINUE TO RISE TO AROUND
593-595 DMS BY 18Z TUE. WIDESPREAD H7 TEMPS IN THE +15 TO +17 DEG
C RANGE SUGGESTS ANOTHER WARM DAY FOR MOST AREAS. OPTED TO STAY
CLOSE TO GUIDANCE...ESPECIALLY ALONG/EAST OF THE LARAMIE RANGE
WHERE WEAK EAST-TO-SOUTHEAST UPSLOPE COULD LIMIT POTENTIAL HIGHS.
STILL SHOULD SEE WIDESPREAD HIGHS AROUND 85-95 ON THE PLAINS
THOUGH. KEPT PRECIP CHANCES CONFINED TO THE MOUNTAINS GIVEN VERY
LIMITED MOISTURE ALOFT ADVERTISED BY THE MODELS. GFS/ECMWF/NAM ALL
CONTINUE TO ADVERTISE A VIGOROUS SHORTWAVE UNDERCUTTING THE RIDGE
AND MOVING FROM SOUTHWEST TO NORTHEAST ACROSS THE CWA ON WED
AFTERNOON/NIGHT. THIS COMES WITH A SUBSTANTIAL PLUME OF MONSOONAL
MOISTURE...SO STILL EXPECT AT LEAST SCATTERED COVERAGE OF
CONVECTION. THINK THE HIGHEST COVERAGE WILL BE ALONG/WEST OF THE
LARAMIE RANGE WITH WESTERLY FLOW IN THE WAKE OF A FAST MOVING
PACIFIC COLD FRONT. SHOULD BE A FAIRLY IMPRESSIVE FROPA FOR A
PACIFIC SYSTEM...WITH H7 TEMPS DROPPING AT LEAST 5 C BETWEEN 00Z
WED AND 12Z THU.

.LONG TERM...(THURSDAY THROUGH NEXT MONDAY)
ISSUED AT 245 PM MDT MON AUG 24 2015

THE ONLY FORECAST CONCERN IN THE MEDIUM RANGE WILL BE A PACIFIC
UPPER LEVEL TROUGH FORECAST TO MOVE EAST OF THE FORECAST AREA ON
THURSDAY. NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED
ON THURSDAY AS A COLD FRONT SLIDES ACROSS THE AREA WEDNESDAY
NIGHT. HIGH TEMPERATURES WILL STILL BE PLEASANT...AND GENERALLY IN
THE 70S TO LOW 80S. WITH THE COOLER AIR ALOFT...EXPECT WIDELY
SCATTERED OR SCATTERED COVERAGE OF SHOWERS AND TSTORMS ACROSS THE
AREA. INCREASED POP BETWEEN 20 TO 30 PERCENT OVER THE HIGH PLAINS.
OTHERWISE...MODELS SHOW THE RETURN OF THE UPPER LEVEL RIDGE BY THE
WEEKEND AS SOUTHWEST FLOW ALOFT INCREASES OVER THE REGION. IT WILL
BE WARMER BY FRIDAY AND DURING THE WEEKEND WITH HIGHS IN THE 80S
TO MID 90S...WARMEST OVER THE LOWER ELEVATIONS. CAN NOT RULE OUT A
FEW ISOLATED THUNDER SHOWERS ACROSS THE AREA AS SOME SUBTROPICAL
MOISTURE WILL OCCASIONALLY MOVE OVER THE FRONT RANGE. EXPECT MOST
OF THIS ACTIVITY TO BE OVER THE MOUNTAINS...ALONG AND WEST OF THE
I25 CORRIDOR. KEPT POP BETWEEN 10 TO 20 PERCENT FOR ISOLATED
THUNDER. OTHERWISE...PRETTY QUIET WEATHER IS EXPECTED THROUGH THE
LAST WEEKEND OF AUGUST.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 533 PM MDT MON AUG 24 2015

VFR. FEW-SCT CUMULUS KRWL-KLAR-KCYS ROUTE WILL DISSIPATE BY 02Z.
OTHERWISE...SCT CIRRUS WILL SPREAD WEST TO EAST TONIGHT FROM
UPSTREAM CONVECTION. SURFACE WINDS WILL BE VARIABLE 5-10 KT DURING
THE TAF PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 219 PM MDT MON AUG 24 2015

WARM AND DRY CONDITIONS WILL PERSIST ACROSS MUCH OF SOUTHEAST WY AND
THE WESTERN NE PANHANDLE THROUGH TUESDAY. MINIMUM AFTERNOON RELATIVE
HUMIDITY VALUES WILL FALL TO BETWEEN 10 AND 15 PERCENT OVER PORTIONS
OF CARBON AND CONVERSE COUNTIES...BUT WINDS ARE LIKELY TO STAY BELOW
CRITICAL THRESHOLDS. NO FIRE WEATHER CONCERNS THROUGH THE REMAINDER
OF THE WEEK WITH COOLER AND MORE MOIST CONDITIONS. THERE IS A CHANCE
FOR MORE WIDESPREAD WETTING RAINS ON WEDNESDAY AFTERNOON AND NIGHT
AS A STRONG PACIFIC COLD FRONT SWEEPS ACROSS THE AREA. TEMPERATURES
WILL REBOUND IN TIME FOR THE WEEKEND...POSSIBLY CONTRIBUTING TO NEAR
CRITICAL FIRE WEATHER CONDITIONS ON SAT/SUN.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

SHORT TERM...CLH
LONG TERM...TJT
AVIATION...MAJ
FIRE WEATHER...CLH


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