Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 220537
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1137 PM MDT THU APR 21 2016

.UPDATE...
ISSUED AT 849 PM MDT THU APR 21 2016

MOSTLY CLEAR SKIES WITH TEMPERATURES A BIT ABOVE NORMAL FOR THE
REST OF TONIGHT ACROSS SE WYOMING AND THE WESTERN NEBRASKA
PANHANDLE AS LIGHT EASTERLY WINDS GRADUALLY BECOME MORE
SOUTHWESTERLY AND DOWNSLOPE FOR MANY AREAS. NOT A LOT OF CHANGE
FOR THE OVERNIGHT PERIOD INTO TOMORROW MORNING FOR THIS UPDATE
ALTHOUGH DID MAKE SOME MINOR CHANGES TO TEMPS AND WINDS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 238 PM MDT THU APR 21 2016

UPPER-LEVEL RIDGING REMAINS IN CONTROL OVER THE CENTRAL ROCKIES THIS
AFTERNOON. A DRY COLUMN AND DEEP SUBSIDENCE SHOULD CONTINUE TO YIELD
TRANQUIL WEATHER CONDITIONS THROUGH FRIDAY. A VERY WARM DAY EXPECTED
TOMORROW AS THE GFS/NAM/ECM/GEM ALL SHOW H7 TEMPERATURES IN THE +8 C
TO +10 DEG C RANGE. THE OVERALL PATTERN SHOULD FAVOR WIDESPREAD HIGH
TEMPERATURES IN THE 70S TO NEAR 80 F. NO PRECIPITATION WILL OCCUR W/
VERY DRY H7-H3 MOISTURE PROFILES. THE MODELS SHOW A STRONG MID-LEVEL
SHORTWAVE MOVING RAPIDLY ACROSS THE GREAT BASIN ON FRIDAY NIGHT WITH
SOUTHWEST FLOW ALOFT OVERSPREADING THE CWA ON SATURDAY. PCPN CHANCES
WILL INCREASE FROM WEST TO EAST AS A RESULT. GFS SBCAPE BETWEEN 250-
500 J/KG SHOULD SUPPORT THUNDERSTORMS ON SATURDAY AFTERNOON. LOOKING
AT A POTENTIAL HIGH WIND EPISODE STARTING LATE SATURDAY NIGHT AS THE
AFOREMENTIONED WAVE ADVANCES EAST ACROSS THE CWA. LOWER-LEVEL HEIGHT
GRADIENTS STRENGTHEN DRAMATICALLY BETWEEN 06Z AND 12Z SUN...WITH THE
GFS 850 MILLIBAR CAG-CPR GRADIENT PEAKING AROUND 115 METERS. THIS IS
VERY IMPRESSIVE FOR LATE APRIL...ESPECIALLY CONSIDERING 750 MILLIBAR
FLOW BETWEEN 70-80 KTS OVER OUR WIND CORRIDORS. THERE IS A VERY GOOD
CHANCE THAT HIGH WIND HEADLINES WILL EVENTUALLY BE NEEDED. COULD SEE
50 KT GUSTS SPREAD INTO CHEYENNE AS WELL IF H7 COLD ADVECTION YIELDS
SUFFICIENTLY STEEP LAPSE RATES.

.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 238 PM MDT THU APR 21 2016

STRONG WINDS LOOK TO CONTINUE ACROSS SOUTHEAST WYOMING SUNDAY AS
THE SURFACE AND 5H LOW DRIFT SLOWLY EASTWARD ALONG THE NEB/S
DAKOTA BORDER. 7H WINDS OF 55 TO 65 KTS PROGGED OVER PARTS OF SE
WY SUNDAY MORNING...EASING DURING THE AFTERNOON WHILE BECOMING
MORE NORTHWESTERLY. STRONGEST WINDS SHOULD BE IN THE WIND PRONE
AREAS...MAINLY SUNDAY MORNING. OTHERWISE EXPECT WRAP-AROUND
SHOWERS ACROSS MUCH OF THE CWA SUNDAY DIMINISHING SUNDAY EVENING
AS THE UPPER LOW MOVES FARTHER AWAY. SHORT RIDGE TRANSLATES ACROSS
SUNDAY NIGHT INTO MONDAY MORNING AHEAD OF THE NEXT UPPER LOW WHICH
WILL MOVE INTO THE WESTERN CONUS. SHOULD SEE SHOWERS AND A FEW
STORM INCREASING OVER SE WY MONDAY AFTERNOON WITH SURFACE UPSLOPE
FLOW UNDERNEATH DECENT DIFFLUENT UPPER PATTERN. INSTABILITIES NOT
MUCH BUT A FEW STORMS POSSIBLE. FAIRLY WIDESPREAD RAIN AND SNOW
SEEN FOR MONDAY NIGHT AND TUESDAY AS THE SYSTEM MOVES ACROSS THE
CENTRAL ROCKYS INTO THE CENTRAL PLAINS WITH SOME DECENT SNOWS
POSSIBLE OVER AND CLOSE TO THE MTNS LATER MONDAY NIGHT INTO
TUESDAY AS TEMPS COOL. PRECIPITATION CONTINUING ON TUESDAY BEFORE
TAPERING OFF TUESDAY NIGHT INTO WEDS AS THE SYSTEM MOVES ACROSS
NEBRASKA. MAX TEMPS TUESDAY AND WEDS LOOK TOO WARM GIVEN EXPECTED
CONDITIONS AND HAVE UNDERCUT. MAY NEED TO COOL THEM EVEN MORE.
MAINLY DRY WEDS NIGHT INTO THURSDAY AS ANOTHER SHORT UPPER RIDGE
MOVES BY THEN THEN NEXT UPPER LOW DRIFTING INTO THE FAR SW CONUS
MAY SPREAD SHOWERS TO WESTERN PARTS OF THE CWA BY LATE THURSDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1135 PM MDT THU APR 21 2016

VFR. GUSTS OF 23 TO 30 KNOTS FROM 15Z TO 01Z.

&&

.FIRE WEATHER...
ISSUED AT 215 AM MDT THU APR 21 2016

MINIMAL FIRE WEATHER CONCERNS ARE FORECAST THROUGH FRIDAY WITH
DRIER AND WARMER CONDITIONS AS A RIDGE OF HIGH PRESSURE DOMINATES
THE DISTRICTS. MINIMUM HUMIDITIES FOR THE VALLEYS AND PLAINS LOWER
TO 20 TO 25 PERCENT THIS AFTERNOON...AND 15 TO 20 PERCENT FRIDAY
AFTERNOON. WIND SPEEDS WILL REMAIN BELOW CRITICAL THRESHOLDS.
HIGHER HUMIDITIES...COOLER TEMPERATURES AND CHANCES FOR SHOWERS
AND ISOLATED THUNDERSTORMS ARE PREDICTED THIS WEEKEND INTO EARLY
NEXT WEEK.

&&

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

$$

UPDATE...JG
SHORT TERM...CLH
LONG TERM...RE
AVIATION...RUBIN
FIRE WEATHER...MAJ



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