Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 241126
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
526 AM MDT THU APR 24 2014

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 338 AM MDT THU APR 24 2014

FAIRLY TRANQUIL WEATHER PATTERN THROUGH MUCH OF THE SHORT TERM.
SHORTWAVE IS CURRENTLY MOVING THROUGH EASTERN MONTANA WITH THE
TROUGH AXIS JUST TO THE EAST OF THE CWA. MID AND HIGH LEVEL CLOUDS
ARE CLEARING OUT NICELY IN THE SUBSIDENCE BEHIND THE SHORTWAVE.
WINDS THIS AFTN WILL BE WEAKER THAN YESTERDAY AS THE FLOW ALOFT IS
NOT AS STRONG. 1 KM AGL WINDS ARE GENERALLY 30-35 KTS OVER
SOUTHEAST WY WITH 20-25 KTS OVER THE WESTERN NEBRASKA PANHANDLE.
WITH THE DEEP MIXING THAT IS PROGGED...AFTN MIN RH VALUES WILL
DROP TO 15-20 PERCENT OVER MUCH OF THE PLAINS. UPGRADED THE FIRE
WEATHER WATCH TO A RED FLAG WARNING FOR FWZ 312 AND 313 (THE
SOUTHERN NEBRASKA PANHANDLE) AS RH VALUES WILL BE AROUND 15
PERCENT WITH WEST WIND GUSTS TO 25-30 MPH. WIND WILL DROP OFF
NICELY TONIGHT AS A SHORTWAVE RIDGE MOVES OVERHEAD ALONG WITH A
LOSS OF LLVL MIXING.

FLOW ALOFT BECOMES MORE SOUTHWESTERLY ON FRI AS A LARGE SCALE
TROUGH APPROACHES THE WEST COAST. SFC WINDS WILL TURN TO THE SOUTH
AND SOUTHEAST LATE IN THE DAY. ABOUT 5 DEGREES OF WARMING IS
EXPECTED AS 700MB TEMPS WARM TO AROUND 7C BY THE AFTN. WILL LIKELY
BE GREATER COVERAGE OF AFTN CUMULUS AS LI VALUES FALL TO AROUND
0C...HOWEVER SHOWER DEVELOPMENT WILL BE LIMITED. FLOW ALOFT BACKS
TO THE SOUTH ON SAT AS DEEP UPPER TROUGH PUSHES INTO UTAH. ANOTHER
WARM DAY WITH TEMPS ABOVE NORMAL. CLOUD COVER WILL BE ON THE
INCREASE BY THE AFTN AS LARGE SCALE LIFT BEGINS TO SPREAD OVER THE
REGION. INCLUDED A SLIGHT CHANCE OF TSTMS OVER THE CWA DURING THE
AFTN WITH THE INCREASING UPPER LEVEL DIVERGENCE AND WEAK
INSTABILITY. COLD FRONT DOES NOT MOVE OVER THE CWA UNTIL LATE SAT
EVENING AND INTO SAT NIGHT.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 338 AM MDT THU APR 24 2014

SATURDAY NIGHT...TIGHTLY WRAPPED UPPER TROUGH PROGGED TO MOVE FROM
THE FOUR CORNERS TO EAST CENTRAL OR SOUTHEAST COLORADO BY
DAWN...WITH SURFACE LOW PRESSURE STRENGTHENING OVER WESTERN
NEBRASKA. ALTHOUGH LOW LEVEL WINDS WILL REMAIN DOWNSLOPE
NORTHWESTERLY OVER OUR COUNTIES...IT APPEARS THAT STRONG UPWARD
VERTICAL MOTION WILL BE ABLE TO COMPENSATE FOR LOW LEVEL DOWNSLOPE...
PRODUCING SCATTERED TO NUMEROUS SHOWERS...WITH GREATEST AREAL
COVERAGE OVER OUR WESTERN COUNTIES. TEMPERATURES APPEAR COLD ENOUGH
FOR A TRANSITION TO SNOW OVER MOST LOWER ELEVATIONS EXCEPT WESTERN
NEBRASKA. ENOUGH DYNAMICAL LIFT FOR ISOLATED EVENING THUNDERSTORMS.

SUNDAY...STRONG UPPER TROUGH SLOWLY PIVOTS OVER NORTHEAST COLORADO
AND WESTERN NEBRASKA...PRODUCING PLENTY OF UPWARD VERTICAL MOTION
AND SCATTERED TO NUMEROUS SHOWERS OVER OUR COUNTIES...MOST NUMEROUS
OVER THE OROGRAPHICALLY FAVORED MOUNTAINS. WILL BE INTERESTING TO
SEE OF TEMPERATURES WILL BE COLD ENOUGH FOR SNOW...THOUGH FOR NOW...
PROGGED THICKNESSES SUGGEST MOSTLY RAIN EAST OF INTERSTATE 25.
BLUSTERY AND RAW DAY WITH BRISK NORTH WINDS AND COLD TEMPERATURES.

MONDAY...UPPER TROUGH PROGGED TO SLOWLY DRIFT EAST...THOUGH STILL
PRODUCING AT LEAST SCATTERED SHOWERS OVER OUR COUNTIES IN THE
WRAPAROUND PRECIPITATION BAND. CONTINUED COOL AND WINDY PER PROGGED
GRADIENTS AND THICKNESSES.

TUESDAY...ANOTHER WINDY AND UNSETTLED DAY AS THE UPPER TROUGH SLOWLY
PROGRESSES EASTWARD...THOUGH WITH ANOTHER VORTICITY TAIL LIKELY
AFFECTING OUR EASTERN COUNTIES IN THE AFTERNOON IN THE WRAPAROUND
PRECIPITATION BAND.

WEDNESDAY...MOST PRECIPITATION SHOULD COME TO AN END AS THE UPPER
TROUGH PROGRESSES FURTHER EAST...AND BELIEVE THE ECMWF IS OVERDONE
WITH RESPECT TO QPF...AND PREFER THE DRIER GFS QPF VERSION.
CONTINUED COOL AND WINDY PER PROGGED GRADIENTS AND THICKNESSES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 523 AM MDT THU APR 24 2014

VFR PREVAILS. WINDS GUSTING 25 TO 35 KNOTS THROUGH 00Z...THEN
WINDS SUBSIDING.

&&

.FIRE WEATHER...
ISSUED AT 338 AM MDT THU APR 24 2014

TEMPERATURES WILL WARM INTO THE 60S THIS AFTERNOON OVER THE
WESTERN NEBRASKA PANHANDLE. WITH A DRY AIRMASS IN PLACE...MINIMUM
AFTERNOON HUMIDITY VALUES WILL DROP TO AROUND 15 PERCENT. IN
ADDITION...WEST WINDS WILL BE BREEZY IN THE AFTERNOON WITH GUSTS TO
25-30 MPH. A RED FLAG WARNING IS IN EFFECT FOR THE SOUTHERN
PANHANDLE THIS AFTERNOON. WARM TEMPERATURES WILL CONTINUE THROUGH
SATURDAY WITH HUMIDITY VALUES DROPPING INTO THE 15-20 PERCENT
RANGE. WINDS WILL BE WEAKER ON FRIDAY AND SATURDAY...SO ONLY AN
ELEVATED FIRE WEATHER THREAT IS FORECASTED AT THIS TIME.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...RED FLAG WARNING FROM NOON TODAY TO 7 PM MDT THIS EVENING FOR
     NEZ312-313.

&&

$$

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






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