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000
FXUS65 KCYS 150926
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
326 AM MDT WED MAY 15 2013

.SHORT TERM...(TODAY THROUGH THURSDAY NIGHT)
ISSUED AT 324 AM MDT WED MAY 15 2013

A COLD FRONT HAS BACKED INTO SOUTHEAST WYOMING AND AT 08Z WAS
LOCATED FROM K82V TO KCLM AND THEN TO THE NORTHWEST. THAT BOUNDARY
WILL CONTINUE TO MOVE WEST AND INTO THE LARAMIE VALLEY THIS
MORNING. BEHIND THE FRONT...THE SURFACE WINDS TURN TO THE EAST OR
SOUTHEAST AND THE BOUNDARY LAYER MOISTURE INCREASES. SURFACE DEW
POINTS WILL BE BETWEEN 45F AND 50F AT ELEVATIONS BELOW 5000 FEET
MSL IN THE AFTERNOON. A SHORTWAVE TROUGH ALSO APPROACHES FROM THE
WEST THIS AFTERNOON AND WILL MOVE ACROSS THE CWA TONIGHT. THE
RESULT WILL BE AT LEAST A SCATTERED COVERAGE OF THUNDERSTORMS IN
THE AFTERNOON AND EARLY EVENING HOURS.

SOME OF THE STORMS LOOK TO BECOME STRONG NEAR THE EASTERN WYOMING
BORDER THIS AFTERNOON. THE LOW LEVEL THETA RIDGE AXIS WILL BE OVER
THAT AREA ALONG WITH STEEPER LAPSE RATES. CAPE VALUES ALSO APPROACH
1000 K/KG OVER THAT PART OF THE CWA. THE BEST 0-6KM SHEAR WILL OCCUR
OVER THE NORTH PART OF THE CWA. HAIL...GENERALLY SMALL...WIND GUSTS
TO 50 MPH AND A PERIOD OF MODERATE RAINFALL CAN BE EXPECTED WITH THE
ACTIVITY NEAR THE EASTERN WYOMING BORDER. AREAS FURTHER TO THE EAST
MAY BE CAPPED FOR MUCH OF THE AFTERNOON PER FORECAST RAOBS.

AS THE SHORTWAVE TROUGH MOVES EAST TONIGHT...SOME SHOWERS AND
EVENING THUNDERSTORMS WILL PERSIST AHEAD OF THE FEATURE. DRIER AIR
WILL MOVE BACK OVER THE CWA FROM WEST TO EAST WITH TROUGH PASSAGE
AND WILL ALSO PUSH THE LOW LEVEL THETA RIDGE AXIS TO ALONG THE
EASTERN CWA BORDER THURSDAY AFTERNOON. MOST OF THE THUNDERSTORMS
WILL OCCUR OVER THE PANHANDLE THURSDAY AFTERNOON WITH SOME POSSIBLY
STRONG FROM KCDR TO KSNY. IN AREAS ALONG AND WEST OF THE LARAMIE
RANGE...GUSTY WESTERLY WINDS WILL OCCUR ON THURSDAY. DRIER
CONDITIONS WILL BE OVER THE CWA AFTER THURSDAY EVENING.

TEMPERATURES WILL BE COOLER TODAY OVER THE CWA BEHIND THE FRONT AND
THEN WARM SOME FOR THURSDAY.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 324 AM MDT WED MAY 15 2013

WARM AND MAINLY DRY WEATHER EXPECTED FRIDAY AS THE CWA LOOKS TO
SEE SOME DRY AIR ADVECTION IN SW FLOW AHEAD OF NEXT UPPER TROF
THAT WILL BE OVER THE WESTERN PART OF THE COUNTRY. THIS UPPER TROF
WILL MOVE SLOWLY EAST OVER THE WEEKEND BRINGING INCREASING CHANCES
FOR SHOWERS AND A FEW STORMS ALONG WITH A COOLDOWN. BEST CHANCES
FOR STORMS WILL BE SATURDAY...MAINLY OVER THE PANHANDLE WHERE
BETTER INSTABILITY SHOULD RESIDE. SUNDAY AND MONDAY LOOKING RATHER
COOL WITH AT LEAST SCATTERED SHOWERS AS UPPER TROF BROADENS SOME
AND CONTINUES A SLOW DRIFT EASTWARD. TROF AXIS SHOULD MOVE EAST OF
THE CWA BY TUESDAY WITH DRIER AND WARMER CONDITIONS BEGINNING TO
RETURN AT THAT TIME.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 324 AM MDT WED MAY 15 2013

VFR EXPECTED OVER ALL TERMINALS FOR THE MOST PART DURING THE
PERIOD. WIDELY SCATTERED SHOWERS AND A FEW TSTMS EXPECTED TO FORM
THIS AFTERNOON WITH BRIEF GUSTY WINDS ASSOCIATED WITH SOME OF
THEM. ACTIVITY WILL DIMINISH DURING THE EVENING HOURS.

&&

.FIRE WEATHER...
ISSUED AT 324 AM MDT WED MAY 15 2013

COOLER AND MORE HUMID AIR WILL BE OVER THE CWA TODAY BEHIND THE
PASSAGE OF A COLD FRONT. AT LEAST A SCATTERED COVERAGE OF
AFTERNOON AND EVENING THUNDERSTORMS WILL ALSO OCCUR OVER THE CWA.
SOME OF THOSE STORMS WILL PRODUCE MODERATE RAINFALL AS WELL AS
BRIEF WIND GUSTS TO 50 MPH.

DRIER AIR WILL MOVE OVER THE REGION ON THURSDAY WITH THE BULK OF
THE SHOWER AND STORM ACTIVITY OVER THE PANHANDLE. IN AREAS ALONG
AND WEST OF THE LARAMIE RANGE...WESTERLY SURFACE WINDS WILL GUST
AS HIGH AS 35 MPH ON THURSDAY. MINIMUM RELATIVE HUMIDITY VALUES
WILL BE BETWEEN 15 AND 25 PERCENT OVER THE LOWER ELEVATIONS ON
THURSDAY...WITHE THE LOWER ELEVATIONS OVER CARBON COUNTY. FRIDAY
WILL BE AN EVEN WARMER...DRIER AND WINDIER DAY WITH CRITICAL FIRE
WEATHER CONDITIONS POSSIBLE OVER THE LOWER ELEVATIONS. COOLER
TEMPERATURES WILL RETURN TO THE REGION STARTING ON SUNDAY AND
LASTING THROUGH EARLY NEXT WEEK.

&&

.HYDROLOGY...
ISSUED AT 324 AM MDT WED MAY 15 2013

TEMPERATURES WILL BE COOLER TODAY OVER SOUTHEAST WYOMING ALONG
WITH AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. WARMER...
DRIER AND DAYTIME WINDY CONDITIONS ARE EXPECTED FOR THURSDAY AND
ESPECIALLY FRIDAY AND SATURDAY. THEN COOLER TEMPERATURES WITH A
CHANCE OF SHOWERS CAN BE EXPECTED FOR SUNDAY AND EARLY NEXT WEEK.

THE RESULT WILL BE A CONTINUED STEADY SNOW MELT AND RISE IN THE
RIVER LEVELS OVER AND NEAR THE SNOWY AND SIERRA MADRE RANGES.
ABOUT AN INCH OF SWE HAS BEEN LOST EACH DAY RECENTLY AND THAT WILL
LIKELY CONTINUE THROUGH THE WEEKEND BEFORE SLOWING SOME. RIVERS
ARE STILL WELL WITHIN THEIR BANKS...BUT SOME BANKFULL CONDITIONS
WILL BE APPROACHED BY THE WEEKEND IN THE RIVERS AND STREAMS
COMING OUT OF THE MOUNTAINS. AT ELEVATIONS ABOVE MAINLY 9000 FEET
MSL THERE IS STILL BETWEEN 10 AND 25 INCHES OF SWE.

&&

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

&&

$$

SHORT TERM...WEILAND
LONG TERM...RE
AVIATION...RE
FIRE WEATHER...WEILAND
HYDROLOGY...WEILAND