000
FXUS65 KCYS 242056
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
256 PM MDT FRI MAY 24 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 250 PM MDT FRI MAY 24 2013

QUIET SO FAR THIS AFTERNOON BUT SOME CONVECTION MAY STILL DEVELOP
MAINLY OVER THE SOUTHERN NEBRASKA PANHANDLE INTO EARLY THIS
EVENING NEAR A WEAK SFC BOUNDARY. OTHERWISE A RATHER PERSISTENT
PATTERN WILL BE OVER THE AREA THROUGH THE WEEKEND WITH SW FLOW
ALOFT AHEAD OF UPPER TROFFING OVER THE WESTERN PART OF THE
COUNTRY. WEAK IMPULSES MOVING NORTHEAST SHOULD COMBINE WITH SOME
INSTABILITY TO PRODUCE WIDELY SCATTERED SHOWERS AND TSTRMS OVER
MAINLY THE PANHANDLE AGAIN SATURDAY AND SUNDAY WHERE SFC BOUNDARY
SHOULD MEANDER. CURRENTLY IT APPEARS THE STRONGER STORMS WILL BE
JUST EAST OF THE CWA BUT WILL HAVE TO WATCH. TEMPERATURES
REMAINING WARM BOTH DAYS.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 247 PM MDT FRI MAY 24 2013

MODELS IN GOOD AGREEMENT EARLY NEXT WEEK...ALTHOUGH THEY DIVERGE
BY THE MIDDLE AND END OF THE WEEK REGARDING A PACIFIC STORM
SYSTEM MOVING ONSHORE MONDAY. AS THIS SYSTEM MOVES ONSHORE ON
MONDAY...UPPER LEVEL SOUTHWEST FLOW WILL CONTINUE WITH WARMER THAN
NORMAL TEMPERATURES IN THE 70S AND 80S EXPECTED ON MEMORIAL DAY. A
DRYLINE WILL BE LOCATED OVER THE HIGH PLAINS...MOVING EASTWARD
INTO WESTERN NEBRASKA EARLY MONDAY MORNING AND THEN RETREATING
WESTWARD TOWARDS THE LARAMIE RANGE DURING THE DAY. ALONG AND EAST
OF THIS BOUNDARY WILL BE THE LIKELY LOCATION OF THUNDERSTORM
DEVELOPMENT ON MEMORIAL DAY...WITH THE BEST CHANCE FOR STORMS
ACROSS WESTERN NEBRASKA. KEPT POP BETWEEN 20 TO 30 PERCENT IN
THESE AREAS...AND BELOW 15 PERCENT WEST OF A LINE FROM CHEYENNE TO
DOUGLAS. A FEW OF THESE THUNDERSTORMS MAY BECOME SEVERE MONDAY
EVENING WITH PLENTY OF INSTABILITY AND SOME LLVL SHEAR AS A WEAK
SHORTWAVE TROUGH MOVES ACROSS CENTRAL WYOMING.

AS WITH THE 00Z MODEL RUNS FROM LAST NIGHT...THE ECMWF CONTINUES
TO SHOW THE UPPER LEVEL PACIFIC TROUGH BECOMING A CLOSED LOW
ACROSS THE GREAT BASIN REGION ON TUESDAY...AND THEN EVENTUALLY
TRACKING THIS LOW EASTWARD AND NORTHEASTWARD BY THURSDAY. ALL THE
OTHER MODELS SHOW AN OPEN WAVE NEGATIVELY TILTED TROUGH QUICKLY
PUSHING ACROSS THE FORECAST AREA ON WEDNESDAY. ENSEMBLES FORECASTS
ARE NOT TRENDING IN ANY PARTICULAR DIRECTION...SO ONLY SLIGHTLY
INCREASED POP WITH A CHANCE OF SHOWERS AND THUNDERSTORMS LATE
TUESDAY THROUGH THURSDAY WITH THE HIGHEST POP ON WEDNESDAY BETWEEN
30 TO 50 PERCENT. THE ECMWF IS THE WETTER SOLUTION...AS THE LLVL
FRONT/DRYLINE REMAINS NEARLY STATIONARY OVER THE HIGH PLAINS WHILE
THE GFS/GEM SOLUTION SHOWS THE BOUNDARY PUSHING NORTHWARD AS THE
TROUGH AXIS QUICKLY MOVES NORTHEAST ON WEDNESDAY. TEMPERATURES
WILL LOWER SLIGHTLY NEXT WEEK AS THE TROUGH AXIS MOVES OVER
WYOMING...INTO THE 60S AND 70S FOR HIGHS BY THURSDAY AND FRIDAY.
LOWS WILL REMAIN NEAR NORMAL OR A FEW DEGREES ABOVE.

&&

.AVIATION...(FOR THE 18Z TAF ISSUANCE)
ISSUED AT 1132 AM MDT FRI MAY 24 2013

VFR CONDITIONS WILL PREVAIL THIS AFTERNOON ACROSS SOUTHEAST WYOMING
AND WESTERN NEBRASKA. THE ONLY EXCEPTION IS KSNY...WHICH IS HOLDING
ONTO A LOW CIG AROUND 1500 FEET AGL EARLY THIS AFTERNOON. EXPECT
THESE LOW CLOUDS TO LIFT BY 19Z. OTHERWISE...GUSTY SOUTHERLY WINDS
ARE EXPECTED ACROSS SOUTHEAST WYOMING AND PORTIONS OF WESTERN
NEBRASKA...WITH GUSTS UP TO 25 KNOTS. ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS WILL QUICKLY DEVELOP LATE THIS AFTERNOON AFTER 21Z
WELL EAST OF THE LARAMIE RANGE INTO NEBRASKA. THESE STORMS MAY
PRODUCE FREQUENT CLOUD TO GROUND LIGHTNING...VERY HEAVY RAINS/MVFR
CONDITIONS...AND GUSTY AND ERRATIC WINDS WITH SEVERE TURBULENCE
POSSIBLE. FOG IS LIKELY TO RETURN TO WESTERN NEBRASKA AFTER MIDNIGHT
WITH IFR VIS EXPECT BY SUNRISE.


&&

.FIRE WEATHER...
ISSUED AT 250 PM MDT FRI MAY 24 2013

GUSTY WINDS AND LOW AFTERNOON RELATIVE HUMIDITIES WILL OCCUR IN
THE AFTERNOONS OVER WESTERN PARTS OF THE CWA BUT CONCERNS WILL BE
MITIGATED BY NON-FAVORABLE FUELS. OTHERWISE WARM CONDITIONS WILL
CONTINUE INTO EARLY NEXT WEEK. BEST CHANCES FOR SHOWERS AND TSTMS
WILL BE IN THE AFTERNOONS AND EVENING MAINLY OVER THE NEB
PANHANDLE.

&&

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

$$

SHORT TERM...RE
LONG TERM...TJT
AVIATION...TJT
FIRE WEATHER...RE