Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 221745
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1145 AM MDT TUE APR 22 2014

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 341 AM MDT TUE APR 22 2014

TODAY...RIDGE AXIS ALOFT MOVES TO THE EAST OF OUR COUNTIES WITH
SOUTHWEST FLOW ALOFT DEVELOPING...PRODUCING INCREASING SOUTH WINDS.
LOOKS LIKE ENOUGH LOW AND MID LEVEL MOISTURE...AND 850/700 MB
THETA-E RIDGE AXIS TO PRODUCE ISOLATED TO SCATTERED AFTERNOON
THUNDERSTORMS IN THE DIFFLUENT FLOW ALOFT. MAY SEE A FEW STRONG
STORMS OVER WESTERN NEBRASKA WITH THE COMBINATION OF FORECAST SHEAR
AND INSTABILITY.

TONIGHT...NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT ROTATES UP
THROUGH WESTERN WYOMING...SENDING A POWERFUL PACIFIC ORIGIN COLD
FRONT INTO OUR WESTERN AND CENTRAL COUNTIES. OTHER THAN OROGRAPHIC
SHOWERS OVER THE SNOWY AND SIERRA MADRE RANGES...NOT MUCH OTHER
PRECIPITATION EXPECTED TO DUE STRONG WEST WINDS AND DOWNSLOPING.

WEDNESDAY...STRONG COLD AIR ADVECTION CONTINUES IN THE WAKE OF THE
COLD FRONTAL PASSAGE WITH STEADY OR SLOWLY FALLING TEMPERATURES.
PROGGED WINDS COULD APPROACH HIGH WIND CRITERIA...ESPECIALLY AT
TYPICALLY WIND PRONE LOCATIONS...THOUGH STILL NOT ENOUGH CONFIDENCE
TO WARRANT A HIGH WIND WATCH.

WEDNESDAY NIGHT...WINDS SHOULD BEGIN TO WEAKEN AFTER SUNSET DUE TO
LOSS OF DAYTIME HEATING. STILL DRY WITH LIMITED LOW AND MID LEVEL
MOISTURE.

THURSDAY...NOT QUITE AS WINDY AS WEDNESDAY AS WINDS ALOFT AND NEAR
THE SURFACE DECREASE. LOOKS LIKELY A DRY DAY AS LOW AND MID LEVEL
MOISTURE IS SCARCE.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 AM MDT TUE APR 22 2014

SOUTHWESTERLY FLOW ALOFT STRENGTHENS ON FRI IN ADVANCE OF LARGE
SCALE TROUGH THAT MOVES INTO THE WEST COAST. TEMPS WILL BE
SLIGHTLY ABOVE NORMAL WITH 700MB TEMPS OF 4-6C BY THE AFTN.
SOUTHEASTERLY WINDS WILL STRENGTHEN OVER THE PLAINS ON FRI NIGHT
AND INTO SAT AS PRESSURE FALLS OCCUR IN WESTERN WY. MODELS ARE IN
SOMEWHAT BETTER AGREEMENT WITH THE UPPER TROUGH AS IT SWINGS INTO
UTAH AND COLORADO ON SAT. THE GFS STILL INDICATES A CLOSED LOW
CENTER DEVELOPING OVER WESTERN NEBRASKA BY SAT NIGHT AND SUN
MORNING...WHEREAS THE ECMWF IS MORE OPEN WITH THE TROUGH. LARGE
SCALE LIFT IS PROGGED TO INCREASE OVER THE REGION BY SAT EVENING.
COULD BE SOME TSTMS ON SAT AFTN AND EVENING WITH STRONG DYNAMICAL
SUPPORT AND LI VALUES AROUND -1C.  THE GFS INDICATES A GOOD TROWAL
EXTENDING INTO THE NORTHERN PANHANDLE AS THE SYSTEM WRAPS UP ON
SAT NIGHT. STILL LOOKING LIKE THIS SYSTEM HAS THE POTENTIAL TO
BRING WIDESPREAD PRECIP TO THE AREA...WITH QPF AMOUNTS DEPENDENT
ON THE EVENTUAL TRACK AND SPEED OF THE SYSTEM. AIRMASS IS NOT
PARTICULARLY COLD ON SAT NIGHT DUE TO THE SYSTEMS PACIFIC ORIGIN
AND WET BULB TEMPS ARE LARGELY 35-40F OVER THE PLAINS. SO THINKING
THAT SNOW WILL REMAIN CONFINED TO ELEVATIONS ABOVE 6000-7000 FT.
REX BLOCK DEVELOPS ACROSS THE NORTHERN AND CENTRAL PLAINS BY MON
WITH A COOL AND SHOWERY REGIME OVER THE CWA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1139 AM MDT TUE APR 22 2014

BREEZY TO WINDY CONDITIONS WILL PERSIST ACROSS THE AREA TODAY AND
TONIGHT. ISOLATED TO SCATTERED SHOWERS WILL BE FOUND OVER
SOUTHEAST WYOMING AND NORTHEAST NEBRASKA TODAY AND INTO THIS
EVENING. ERRATIC WIND GUSTS POSSIBLE IN AND AROUND SHOWER
ACTIVITY. A STRAY THUNDERSTORM ALSO POSSIBLE TODAY. A COLD FRONT
WILL PUSH ACROSS THE AREA LATE TONIGHT FROM WEST TO EAST. GUSTY
WEST TO NORTHWEST WINDS WILL OCCUR ALONG AND BEHIND THE FRONT.
GUSTS OVER 50 MPH POSSIBLE IN FAVORED WIND PRONE AREAS OF
SOUTHEAST WYOMING. GUSTY WINDS WILL CONTINUE WEDNESDAY BUT DROP
OFF BY WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 341 AM MDT TUE APR 22 2014

AFTERNOON HUMIDITIES WILL REMAIN IN THE 15 TO 25
PERCENT RANGE THROUGH THURSDAY...THOUGH WINDS WILL INCREASE MARKEDLY
ON WEDNESDAY AND THURSDAY...IN THE WAKE OF A COLD FRONTAL PASSAGE.

&&

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

$$

SHORT TERM...RUBIN
LONG TERM...FINCH
AVIATION...SML
FIRE WEATHER...RUBIN






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