Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KCYS 202133
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
233 PM MST THU NOV 20 2014

.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 230 PM MST THU NOV 20 2014

BATCH OF MOISTURE EVIDENT ACROSS MUCH OF WESTERN WYOMING WILL
SHIFT EAST ACROSS THE CWA OVERNIGHT ALONG WITH A WEAK UPPER
IMPULSE. NOT MUCH EFFECT FROM THIS OTHER THAN SOME MTN SNOW
SHOWERS MAINLY THIS EVENING.

FRIDAY WILL BE ANOTHER FAIRLY MILD AND DRY DAY ACROSS THE CWA
UNDER A GENERALLY WESTERLY FLOW ALOFT. WINDS COULD GET A LITTLE
GUSTY AROUND THE MTNS IN THE AFTERNOON AS SOME 40KT WINDS AT 700MB
PASS ACROSS BUT NOT LOOKING TOO SIGNIFICANT. MUCH MORE SIGNIFICANT
WINDS LOOK TO DEVELOP LATE FRIDAY NIGHT AND SATURDAY AS THE
STRONGER WESTERLIES ALOFT SAG SOUTH OVER THE AREA AND AN
APPROACHING SHORTWAVE INDUCES PRESSURE FALLS OVER THE HIGH PLAINS
INCREASING THE PRESSURE GRADIENT. LOW LEVEL INVERSION SHOULD KEEP
THE STRONGER WINDS OFF THE SFC THROUGH EARLY SATURDAY THEN THE
WINDS SHOULD INCREASE DURING THE DAY AS THE INVERSION IS LOST.
EARLIER FORECAST REASONING LOOKS ON TRACK WITH THE
ARLINGTON/BORDEAUX AREAS LIKELY SEEING THE INITIAL STRONG
WINDS AS 700MB WINDS INCREASE TO OVER 60KTS...WITH OTHER AREAS
LIKELY HOLDING OFF UNTIL A PACIFIC FRONT PASSES ACROSS IN THE LATE
AFTERNOON. GIVEN LATER PERIODS AND TIMING UNCERTAINTIES WILL HOLD
OFF ON A WATCH FOR NOW THOUGH SOME HILITES WILL VERY LIKELY BE
NEEDED EVENTUALLY. OTHERWISE NEXT SLUG OF MOISTURE SHOULD REACH
WESTERN PARTS OF THE CWA SATURDAY AFTERNOON WITH SNOW SHOWERS
INCREASING OVER THAT AREA THROUGH SATURDAY EVENING.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 230 PM MST THU NOV 20 2014

MEDIUM RANGE MODEL GUIDANCE IS IN GOOD AGREEMENT WITH BROAD SCALE
TROUGHING OVER THE CENTRAL US INTO EARLY NEXT WEEK. THIS RESULTS IN
FAST NORTHWEST FLOW ALOFT ANCHORED OVER THE WESTERN STATES FOR MUCH
OF THE EXTENDED PERIOD. A VERY ACTIVE WEATHER PATTERN SHOULD PREVAIL
THROUGH THE PERIOD. NUMEROUS SHOTS OF MIDLEVEL MOISTURE WILL OCCUR
WITH SMALLER SCALE DISTURBANCES EMBEDDED WITHIN THE FLOW...EVIDENCED
BY MODELED 700-300 MILLIBAR RH FIELDS. FAVORABLE OROGRAPHICS LIKELY
FOR THE SNOWIES AND SIERRA MADRES THROUGH AT LEAST TUE WITHIN MOIST
NORTHWEST FLOW REGIME...SO MOUNTAIN SNOW AMOUNTS COULD ACTUALLY GET
QUITE HIGH OVER THE COURSE OF SEVERAL DAYS. WINTER HEADLINES COULD
BE NECESSARY IN THE FUTURE. A WINDY PATTERN TOO WITH MULTIPLE HIGH
WIND EPISODES POSSIBLE. GFS AND ECMWF DIVERGE CONSIDERABLY INTO THE
MIDDLE PART OF NEXT WEEK. GFS SHOWS THE CWA ON THE EASTERN FRINGE OF
AN AMPLIFYING UPPER RIDGE ALONG THE WEST COAST. THE ECMWF SHOWS
THE H25 JET CORE DIRECTLY OVERHEAD. REGARDLESS...THE STRENGTH OF
THIS JET IS PROGGED TO BE IMPRESSIVE WITH 155+ KTS AT H25
SOMEWHERE TO THE NORTHEAST. BOTH SOLUTIONS PLACE THE CWA UNDER
INTENSE SUBSIDENCE IN THE RIGHT EXIT REGION ON TUE NIGHT AND WED.
THIS WOULD BE THE MOST LIKELY TIME FOR A WIDESPREAD WIND EVENT
WITH GFS H85 CAG-CPR GRADIENTS AROUND 60 METERS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1019 AM MST THU NOV 20 2014

VFR CONDITIONS THROUGH THE TAF PERIOD. WINDS WILL BECOME BREEZY
THIS AFTERNOON AT THE WYOMING TERMINALS WITH GUSTS AROUND 25 MPH
POSSIBLE. SCT-TO-BKN COVERAGE OF MID LEVEL CLOUDS AROUND 10K FEET
AGL WILL GRADUALLY SPREAD ACROSS THE AREA TODAY. NO PCPN IS
EXPECTED OUTSIDE OF THE MOUNTAINS.

&&

.FIRE WEATHER...
ISSUED AT 230 PM MST THU NOV 20 2014

NO CONCERNS ANTICIPATED THROUGH SATURDAY AS WEATHER FACTORS WILL
BE NON-CRITICAL. AFTER THAT PERIODS OF STRONG WINDS SHOULD OCCUR
AROUND THE MOUNTAINS SUNDAY INTO NEXT WEEK BUT NO OTHER FACTORS
ARE EXPECTED TO RAISE CONCERNS.

&&

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

$$

SHORT TERM...RAE
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RAE


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.