Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 090501
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1101 PM MDT TUE APR 8 2014

.UPDATE...
ISSUED AT 852 PM MDT TUE APR 8 2014

IT WILL BE A QUIET NIGHT WEATHER WISE WITH LIGHT WINDS AND SOME
CIRRUS IN PLACE. NO CHANGES TO THE CURRENT SHORT TERM FORECAST.
STILL LOOKS LIKE GUSTY WINDS...WARM TEMPERATURES...AND LOW
HUMIDITIES WILL MAKE FOR CONDITIONS FAVORABLE FOR RAPID FIRE
SPREAD TOMORROW...OTHERWISE NO BIG WEATHER CONCERNS THE REST OF
THIS WEEK.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 325 PM MDT TUE APR 8 2014

TONIGHT...VISIBLE SATELLITE IMAGERY SHOWING SCATTERED TO BROKEN
MIDDLE AND HIGH CLOUDS OF VARYING OPACITY...THICKNESS...APPROACHING
FROM NORTHERN WYOMING. QUIESCENT OVERNIGHT EXPECTED AS THE RIDGE
ALOFT FLATTENS. DECENT WEST NORTHWEST FLOW ALOFT WILL AID THE
FURTHER DEVELOPMENT OF A SURFACE LEE TROUGH...KEEPING OUR LOW LEVELS
WELL MIXED AND KEEPING OUR MINIMUM TEMPERATURES ABOVE FREEZING AT
MOST LOCALES...ESPECIALLY JUST LEE OF THE LARAMIE RANGE ALONG THE
INTERSTATE 25 CORRIDOR FROM WHEATLAND TO CHEYENNE.

WEDNESDAY...FAST MOVING POSITIVELY TILTED LOW AMPLITUDE SHORTWAVE
TROUGH SCOOTS QUICKLY ACROSS THE CANADIAN BORDER...SENDING THE NEXT
COLD FRONT SOUTHWARD TO OUR NORTHERN COUNTIES BY LATE IN THE
AFTERNOON. OUR COUNTIES WILL BE IN THE WARM SECTOR...AND WITH
DOWNSLOPE KATABATIC WARMING AND LOWER AIRMASS
MODIFICATION...TEMPERATURES WILL SOAR INTO THE 60S WEST OF I-25 AND
70S TO NEAR 80 DEGREES EAST OF I-25. MAY SEE ENOUGH OROGRAPHICS AND
AFTERNOON HEATING FOR ISOLATED SHOWERS OVER THE SNOWY AND SIERRA
MADRE RANGES IN THE AFTERNOON.

WEDNESDAY NIGHT...AFOREMENTIONED COLD FRONT SLIDES SOUTHWARD ACROSS
OUR COUNTIES. DEEPER LOW AND MID LEVEL MOISTURE...ALONG WITH
ASSOCIATED SHORTWAVE TROUGH ALOFT DYNAMICS WILL LIE OVER OUR
NORTHERN COUNTIES...NORTH OF A DOUGLAS TO ALLIANCE LINE...WHERE 20
TO 40 PERCENT POPS WILL BE PAINTED. BOUNDARY LAYER RELATIVE HUMIDITY
PROGS AS WELL AS UPSLOPE LOW LEVEL WINDS SUGGEST AREAS OF LATE NIGHT
FOG NORTH OF A DOUGLAS TO ALLIANCE LINE.

THURSDAY...INTERESTING AFTERNOON CONVECTIVE SITUATION DEVELOPING AS
THE NEXT POSITIVELY TILTED SHORTWAVE TROUGH ADVANCES ACROSS
WYOMING...WITH AN INVERTED SURFACE TROUGH STRETCHING IN THE
AFTERNOON FROM LIMON COLORADO NORTHWARD TO SCOTTSBLUFF NEBRASKA. BY
LATE AFTERNOON...850/700 MB THETA-E RIDGE AXISES STRETCH FROM DENVER
NORTHEASTWARD TO ALLIANCE NEBRASKA. NAM SHOWS A DECENT UPWARD
VERTICAL MOTION AREA ALONG THE SURFACE TROUGH IN THE AFTERNOON AND
COMBINED WITH PROJECTED CAPE OF 400 JOULES PER KILOGRAM AND LOW
LEVEL CONVERGENCE...EXPECT ISOLATED TO SCATTERED THUNDERSTORMS TO
ERUPT AFTER MID AFTERNOON EAST OF INTERSTATE 25...WITH HIGHEST AREAL
COVERAGE SOUTH OF A PINE BLUFFS TO ALLIANCE LINE.

THURSDAY NIGHT...SHORTWAVE TROUGH ALOFT QUICKLY SWEEPS EAST OF OUR
COUNTIES...AND THE DOWNWARD VERTICAL MOTION IN ITS WAKE WILL HELP
CLEAR CLOUDS AND PRECIPITATION...ALONG WITH BOOSTING WINDS DUE TO
DECENT DOWNWARD TRANSPORT OF MOMENTUM.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 325 PM MDT TUE APR 8 2014

MID TO WARM TEMPERATURES WILL CONTINUE FRIDAY THROUGH MOST OF
SATURDAY UNDER A GENERALLY ZONAL FLOW ALOFT. SIGNIFICANT CHANGES
ENSUE LATE SATURDAY AS A COLD FRONT DIVES SOUTH ACROSS THE CWA
AHEAD OF AN APPROACHING UPPER SHORTWAVE OVER THE PACIFIC NW. GFS
HAS NOW COME MORE INTO LINE WITH THE EC WITH A SOMEWHAT MORE
WESTWARD TRACK WITH THIS SHORTWAVE...RESULTING IN A FAVORABLE
OVERRUNNING SETUP OVER THE CWA LATE SATURDAY NIGHT AND SUNDAY.
SHOULD SEE A FAIRLY WIDESPREAD AREA OF RAIN AND SNOW SPREAD ACROSS
THE CWA LATE SAT NIGHT WITH MOSTLY SNOW SUNDAY AS THICKNESSES DROP
AND COLD CANADIAN AIR BUILDS OVER THE AREA. DAYTIME TIMING OF MUCH
OF THE PCPN MAY HELP TO LIMIT SNOW IMPACTS DUE TO HIGH SUN ANGLE
BUT SOME ACCUMULATIONS LOOKING A DECENT BET...ESPECIALLY OVER
HIGHER ELEVATIONS.

SNOW WILL END LATE SUNDAY WITH THE PASSAGE OF THE UPPER TROF TO
THE EAST WITH WARMING TEMPS MONDAY THROUGH TUESDAY AS THE UPPER
FLOW BACKS FROM NW TO WESTERLY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY EVENING)
ISSUED AT 1039 PM MDT TUE APR 8 2014

LIGHT WINDS WILL INCREASE AFTER SUNRISE WEDNESDAY WITH WINDY
CONDITIONS ACROSS SE WY AND WRN NE PANHANDLE. GUSTS OF 25 TO 35
KTS WILL BE COMMON WEDNESDAY AFTERNOON. VFR THROUGH WEDNESDAY BUT
A COLD FRONT WILL MOVE THROUGH THE AREA WEDNESDAY NIGHT WITH A FEW
RAIN AND SNOW SHOWERS POSSIBLE OVER EAST-CENTRAL WY AND THE FAR
NORTHERN NEBRASKA PANHANDLE.

&&

.FIRE WEATHER...
ISSUED AT 325 PM MDT TUE APR 8 2014

OUR TEAM FIRE WEATHER WATCH HAS BEEN UPGRADED TO A RED FLAG WARNING
FOR WEDNESDAY FROM 10 AM TO 7 PM...AS CONFIDENCE IS NOW HIGH THAT
MINIMUM AFTERNOON HUMIDITIES WILL FALL AT OR BELOW 15
PERCENT...LIKELY EVEN FROM 5 TO 10 PERCENT...EAST OF A LUSK TO
WHEATLAND TO CHEYENNE LINE...WITH STRONG WEST DOWNSLOPING WINDS
EASILY ECLIPSING 25 TO 30 MPH IN THE AFTERNOON WITH HIGHER GUSTS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...RED FLAG WARNING FROM 10 AM TO 7 PM MDT WEDNESDAY FOR WYZ310.

NE...RED FLAG WARNING FROM 10 AM TO 7 PM MDT WEDNESDAY FOR NEZ311>313.

&&

$$

UPDATE...SML
SHORT TERM...RUBIN
LONG TERM...RE
AVIATION...SML
FIRE WEATHER...RUBIN






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