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000
FXUS65 KCYS 192335
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
535 PM MDT SUN MAY 19 2013

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 304 PM MDT SUN MAY 19 2013

SLOW MOVING UPPER LOW WILL REMAIN OVER THE NORTHERN GREAT PLAINS
THROUGH EARLY THIS WEEK...WITH ABUNDANT LOW AND MIDLEVEL MOISTURE
ROTATING CYCLONICALLY AROUND THE LOW CENTER AND OVER THE FORECAST
AREA THROUGH MONDAY NIGHT. SCATTERED SHOWERS WITH A FEW THUNDERSTORMS
HAVE PERSISTED ACROSS THE FORECAST AREA THROUGH MUCH OF TODAY
AND THIS SHOULD CONTINUE THROUGH TONIGHT. A COLD FRONT WILL THEN
MOVE SOUTHEAST ACROSS THE FORECAST AREA EARLY MONDAY
MORNING...WITH HIGH PRESSURE BUILDING INTO THE FORECAST AREA
BEHIND THE FRONT. EXPECTING AN INCREASE IN COVERAGE AND INTENSITY
OF PRECIP ACROSS THE FORECAST AREA WITH THE FRONT WITH MODELS
SHOWING THE MAJORITY OF THE AREA RANGING FROM ONE QUARTER TO
THREE-QUARTERS INCH OF QPF THROUGH LATE MONDAY AFTERNOON. SLIGHTLY
HIGHER AMOUNTS COULD OCCUR IN THE MOUNTAINS OF SOUTHEAST WYOMING
AS WELL. WITH 700MB TEMPERATURES DECREASING TO 0 TO -2C BY MONDAY
MORNING...EXPECTING RAIN TO CHANGE TO SNOW ABOVE 8000 FT IN THE
SNOWY RANGE AND SIERRA MADRE MOUNTAINS TONIGHT. TEMPERATURES WILL
TEETER AROUND 0C THROUGH THE DAY TOMORROW...BUT FEEL THE MAIN
PRECIP TYPE WILL REMAIN SNOW IN THE HIGHER ELEVATIONS SO WENT
AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING
SNOW TONIGHT THROUGH LATE MONDAY AFTERNOON. LOOKING AT SNOW ACCUMS
ROUGHLY 4 TO 8 INCHES ALTHOUGH THERE WILL BE SOME INITIAL MELTING
OF THE SNOW DUE TO RECENT WARM TEMPS. GUSTY NORTHWEST WINDS OF 25
TO 35 MPH WILL OCCUR IN THIS AREA AS WELL AND LOOK TO PRODUCE
BLOWING SNOW CONDITIONS.

HIGH PRESSURE BUILDING IN BEHIND THE FRONT WILL INDUCE PRESSURE
RISES STARTING EARLY TOMORROW MORNING...WITH 700MB WINDS
INCREASING TO BETWEEN 40 AND 50 KTS ALONG AND EAST OF THE LARAMIE
RANGE...WITH 20 TO 30 KTS OUT WEST. FORECAST SOUNDINGS SHOW THE
BOUNDARY LAYER BEGINNING TO MIX EARLY IN THE MORNING...BUT ONLY UP
TO 750 MB OR SO WITH SLIGHTLY HIGHER MIXING HEIGHTS ACROSS THE
WEST. UNIDIRECTIONAL FLOW THROUGH THIS LAYER WILL AID IN MIXING
SOME OF THESE STRONGER WINDS TO THE SURFACE...AND WITH THE
PRESSURE GRADIENT STRENGTHENING THROUGH THE MORNING AS
WELL...EXPECTING NORTHWEST WINDS TO INCREASE QUICK ALONG AND EAST
OF THE LARAMIE RANGE WITH WIDESPREAD GUSTS OF 40 TO 50 MPH
EXPECTED THROUGH MUCH OF THE DAY. EXPECT SLIGHTLY STRONG GUSTS
AROUND 55 MPH ALONG RIDGETOPS AS WELL. WITH THAT SAID...ISSUED A
WIND ADVISORY ACROSS THE ENTIRE NEBRASKA PANHANDLE BEGINNING EARLY
MONDAY MORNING AND CONTINUING THROUGH EARLY EVENING FOR THESE
EXPECTED WINDS. NORTHWEST WINDS ACROSS WYOMING LOOK TO REMAIN
UNDER WARNING CRITERIA SO WILL NOT ISSUE ANY HIGHLIGHTS THERE.
WINDS SHOULD REMAIN BREEZY OVERNIGHT BUT THE INCREASING LLVL
INVERSION AFTER SUNSET WILL KEEP THE STRONGEST WINDS ALOFT.

TEMPS IN GENERAL WILL BE COOLER TOMORROW THAN TODAY BY A GOOD 5 TO
10 DEGREES. PRECIP WILL ALSO BEGIN TO WANE MONDAY NIGHT AS DRIER AIR
FILTERS IN FROM THE WEST.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 400 PM MDT SUN MAY 19 2013

UPPER LEVEL THROUGH WILL BEGIN TO SHIFT OUT OF THE ROCKIES AND
INTO THE PLAINS TUESDAY. DEPENDING ON THE SPEED OF EASTWARD
PROPAGATION OF THE SYSTEM THERE COULD BE A FEW LINGERING RAIN SHOWERS
TUESDAY...BUT GENERALLY LOOKING DRY WITH TEMPERATURES STARTING TO
MODERATE.

TEMPERATURES WILL CONTINUE TO MODERATE WEDNESDAY WITH AN UPPER
LEVEL RIDGE BUILDING ACROSS THE ROCKIES WHILE THE NEXT TROUGH
MOVES ASHORE OFF THE PACIFIC. SOUTHEAST LOW LEVEL FLOW WILL
DEVELOP AHEAD OF THE TROUGH AND IT LOOKS AS THROUGH THE GULF OF
MEXICO WILL BE OPEN...ALLOWING MOIST LOW LEVEL AIR TO ADVECT INTO
THE REGION...ESPECIALLY LATER IN THE WEEK. WILL BEGIN TO SEE
CHANCES FOR SHOWERS AND THUNDERSTORMS BY WEDNESDAY AFTERNOON OVER
THE MOUNTAINS AND ADJACENT PLAINS AS STEEP LAPSE RATES DEVELOP.
THE GREATEST CHANCES FOR THUNDERSTORMS SHOULD BE THURSDAY AND
FRIDAY WITH AN APPROACHING UPPER LEVEL TROUGH AND SOUTH TO
SOUTHEAST LOW LEVEL FLOW.

WEATHER PATTERN MAY REMAIN ACTIVE THROUGH THE WEEKEND WITH THE
UPPER LEVEL TROUGH JUST EAST OF THE AREA WITH SOUTHWEST FLOW ALOFT
OVER THE FORECAST AREA. WOULD NOT BE SURPRISED TO SEE SOME SEVERE
THUNDERSTORMS THURSDAY AND FRIDAY AFTERNOON AND EVENING...OF
COURSE THIS WILL SOMEWHAT DEPEND ON TIMING OF SHORTWAVES THROUGH
THE UPPER LEVEL FLOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY AFTERNOON)
ISSUED AT 529 PM MDT SUN MAY 19 2013

AREA RADAR SHOWING SHOWERS MOVING SOUTH OUT OF NORTH CENTRAL
WYOMING AND SOUUTHWEST SOUTH DAKOTA. EVENTUALLY...IT LOOKS LIKE
MOST OF SOUTHEAST WYOMING WILL BE RAINING...PROBABLY AROUND THE
03-04Z TIMEFRAME HERE AT KCYS. SNOW WILL FALL ABOVE 8500 FEET
TONIGHT WITH THE SNOWY AND SIERRA MADRE RANGES SEEING THE BULK OF
THE SNOW. AS THE EVENING CONTINUES...EXPECT MOUNTAIN OBSCRURATIONS
TO BECOME MORE WIDESPREAD. WRAP AROUND MOISTURE FROM THE LOW
PRESSURE SYSTEM IN WESTERN NEBRASKA LOOKS TO CONTINUE THROUGH MOST
OF MONDAY WITH IFR...MAINLY MVFR CONDITIONS THROUGH THE OVERNIGHT
AND MORNING HOURS. STRONG NORTHWEST WINDS IN THE PANHANDLE
EXPECTED MONDAY WITH GUSTS TO 40KTS EXPECTED.

&&

.FIRE WEATHER...
ISSUED AT 304 PM MDT SUN MAY 19 2013

UPPER LEVEL TROUGH WILL MOVE ACROSS THE FORECAST AREA TONIGHT AND
TOMORROW. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL
ACCOMPANY THIS THE TROUGH. MOST PRECIPITATION WILL FALL AS RAIN
SOME SNOW WILL BE FOUND MAINLY ABOVE 8500 FT. SEVERAL INCHES OF
SNOW IS EXPECTED IN THE SNOWY AND SIERRA MADRE RANGES.
TEMPERATURES WILL BE BELOW NORMAL THE NEXT FEW DAYS BUT WILL WARM
LATER IN THE WEEK. MOSTLY DRY FOR TUESDAY WITH A RIDGE PUSHING
INTO THE AREA BUT THEN CHANCES FOR SHOWERS AND THUNDERSTORMS INTO
THE LAST HALF OF THE WEEK...MAINLY ALONG AND EAST OF THE LARAMIE
RANGE AND INTO THE NEBRASKA PANHANDLE.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM MDT
     MONDAY FOR WYZ112-114.

NE...WIND ADVISORY FROM 8 AM TO 9 PM MDT MONDAY FOR NEZ002-003-
     019>021-054-055-095-096.

&&

$$

SHORT TERM...RJM
LONG TERM...LIEBL
AVIATION...CLAYCOMB
FIRE WEATHER...LIEBL