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000
FXUS65 KCYS 130540
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1140 PM MDT SUN MAY 12 2013

.UPDATE...
ISSUED AT 914 PM MDT SUN MAY 12 2013

QUIET WEATHER AGAIN TONIGHT AS AN UPPER LEVEL RIDGE SHIFTS INTO
THE ROCKIES. CLEAR TO PARTLY CLOUDY SKIES AND RELATIVELY LIGHT
WINDS WILL ALLOW FOR A GOOD DEAL OF RADIATIVE COOLING. THE DRY AIR
AND LIGHT WINDS HAVE ALLOWED TEMPERATURES TO DROP RATHER QUICKLY
FOLLOWING SUNSET. HAVE TWEAKED TEMPERATURES TO SHOW THE FASTER
COOLING. LOWERED LOW TEMPERATURES A FEW DEGREES BUT WESTERLY WINDS
ARE EXPECTED TO INCREASE A BIT LATER TONIGHT WHICH SHOULD KEEP
TEMPERATURES FROM DROPPING TOO FAR.

A FEW ECHOS SHOWING UP ON RADAR TOWARDS THE SIERRA MADRE RANGE THIS
EVENING. A FEW SPRINKLES MAY BE REACHING THE GROUND IN THE
MOUNTAINS...BUT THAT SHOULD BE ALL.

&&

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 330 PM MDT SUN MAY 12 2013

AFTERNOON WATER VAPOR IMAGERY LOOP SHOWS THE UPPER RIDGE AXIS
ANCHORED OVER THE GREAT BASIN AND NORTHERN ROCKIES...FLANKED
BY UPPER TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CONUS.
PACIFIC MID/UPPER LEVEL MOISTURE WAS STREAMING INLAND ACROSS
THE PACIFIC NORTHWEST THEN SOUTHEAST OVER THE NORTH CENTRAL
ROCKIES. THE REGIONAL SURFACE ANALYSIS SHOWED A WARM FRONT
FROM EASTERN MONTANA THROUGH THE NEBRASKA PANHANDLE AND
WESTERN KANSAS. A HIGH PRESSURE RIDGE EXTENDED FROM THE FOUR
CORNERS TO IDAHO. A RATHER EXTENSIVE HIGH BASED CUMULUS CLOUD
FIELD ENCOMPASSED THE CWFA. INSTABILITY AND MOISTURE WAS MORE
LIMITED FOR CONVECTIVE DEVELOPMENT TODAY COMPARED TO YESTERDAY.
RADARS SHOWED A FEW BRIEF LIGHT SHOWERS EAST OF SCOTTSBLUFF
WHERE LAPS CAPE VALUES WERE NEAR 500 J/KG. ANOTHER AREA FOR
POTENTIAL SHOWER DEVELOPMENT THIS AFTERNOON IS THE SOUTHERN
MOUNTAINS. TEMPERATURES WERE 10 TO 15 DEGREES ABOVE SEASONAL
NORMALS WITH 70S TO LOWER 80S. PREVAILING WINDS WERE GUSTY FROM
THE NORTHWEST BETWEEN 15 AND 25 KT.

THE SHORT RANGE MODEL GUIDANCE REMAINS CONSISTENT BRINGING THE
UPPER RIDGE AXIS EAST ACROSS THE CONTINENTAL DIVIDE MONDAY...
THEN FLATTENING OVER THE GREAT PLAINS TUESDAY AS A STRONG
UPPER LOW TRACKS EAST ALONG THE U.S./CANADIAN BORDER. THIS WILL
RESULT IN A WEST TO EAST FLOW ALOFT OVER SOUTHEAST WYOMING AND
WESTERN NEBRASKA FOR TUESDAY. ANY LEFTOVER CONVECTION WILL QUICKLY
DISSIPATE EARLY THIS EVENING...WITH FAIR SKIES AND MILD
TEMPERATURES OVERNIGHT. LOWS WILL BE IN THE 40S TO LOWER 50S.
MONDAY WILL BE A CARBON COPY OF TODAY WITH MOSTLY DRY CONDITIONS
BUT WARMER AS 700MB TEMPERATURES SOAR TO NEAR 12C IN THE
AFTERNOON. EXPECT HIGHS IN THE 80S TO LOWER 90S EAST OF THE
LARAMIE RANGE...WITH 70S TO LOWER 80S LOWER ELEVATIONS WEST OF
THE RANGE. NAM AND SREF BOTH DEPICT WEAK INSTABILITY OVER THE
HIGHER TERRAIN OF SOUTHEAST WYOMING MONDAY AFTERNOON WITH CAPES
APPROACHING 500 J/KG. COULD SEE SOME ISOLATED SHOWERS OR WEAK
TSTORMS DEVELOP OVER THE MOUNTAINS BUT QPF WILL BE LIGHT. WEST TO
SOUTHWEST WINDS INCREASE OVER CARBON COUNTY MONDAY AFTERNOON...
SPREADING EAST ONTO THE PLAINS MONDAY EVENING. THE MIXED BOUNDARY
LAYER AND WARM 700MB TEMPERATURES KEEP OVERNIGHT LOWS IN THE 50S
OUTSIDE THE MOUNTAINS.

TUESDAY WILL FEATURE BREEZY TO WINDY CONDITIONS AS 700MB WINDS
INCREASE TO 40 TO 45 KT FROM THE WEST. A PACIFIC COLD FRONT WILL
MOVE FROM WEST TO EAST TUESDAY AFTERNOON AND EVENING...SHIFTING
WINDS FROM SOUTHWEST TO NORTHWEST. NOT EXPECTING ANY SHOWERS WITH
DRIER AIR ALOFT SUPPRESSING MOISTURE TO THE SOUTH OVER COLORADO.
IT WILL BE ANOTHER VARY WARM AFTERNOON EAST OF THE LARAMIE RANGE
WITH HIGHS IN THE 80S TO LOWER 90S. IT WILL TURN SLIGHTLY COOLER
LATER IN THE DAY WEST OF THE LARAMIE RANGE.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 PM MDT SUN MAY 12 2013

WESTERLY WINDS WILL BEGIN TO WEAKEN ON TUESDAY EVENING AS THE
PRESSURE GRADIENT SLACKENS ACROSS THE REGION.  A WEAK FRONT WILL
TURN THE WINDS NORTHEASTERLY OVER THE PLAINS BY LATE TUESDAY NIGHT.
WEDNESDAY AND THURSDAY WILL BE WARM DAYS ONCE AGAIN WITH 700MB TEMPS
AROUND 9-11C.  CANNOT RULE OUT ISOLATED SHOWERS AND TSTMS MAINLY
ACROSS THE MTNS BOTH AFTERNOONS BUT MID-TO-LLVL MOISTURE IS RATHER
MEAGER.  BY THURSDAY NIGHT A SHORTWAVE IS MOVING INTO THE PACIFIC
NORTHWEST WITH SOUTHWESTERLY MID LEVEL FLOW DEVELOPING AHEAD OF IT.
SFC PRESSURE TROUGH SETS UP OVER WESTERN NEBRASKA ON FRIDAY
AFTN...SETTING THE STAGE FOR ANOTHER VERY DRY AND WARM DAY ACROSS
THE CWA.  THE MODELS DO SHOW HIGHER DEW POINTS (45-50F) JUST OFF TO
THE EAST OF THE CWA IN SOUTHERLY WINDS.  KEPT SLIGHT CHANCE POPS
OUT OF THE PANHANDLE AT THIS POINT...BUT WE WILL SEE IF THIS
HIGHER LLVL MOISTURE COULD MAKE ITS WAY FURTHER WEST. SHORTWAVE
PUSHES ACROSS NORTHERN WY ON SATURDAY MORNING RESULTING IN DRY
WESTERLY WINDS OVER THE CWA. COULD BE QUITE BREEZY ON SATURDAY AS
SOUNDINGS SHOW 30-35 KT MIXING DOWN...ESPECIALLY IN SOUTHEAST WY.
TEMPS WILL COOL INTO THE WEEKEND WITH THE COLD AIR ADVECTION
BEHIND THE SHORTWAVE...WITH NORMAL TO SLIGHTLY BELOW TEMPS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1136 PM MDT SUN MAY 12 2013

VFR. SCATTERED TO BROKEN CLOUDS AT OR ABOVE 10000 FEET AGL.

18Z MONDAY TO 01Z MONDAY EVENING...ISOLATED HIGH BASED MOSTLY DRY
SHOWERS AND THUNDERSTORMS NEAR THE LARAMIE...SNOWY AND SIERRA
MADRE RANGES PRODUCING WIND GUSTS TO 50 MPH AND LOCALIZED
TURBULENCE. MAY SEE A SHOWER OR THUNDERSTORM IN THE VICINITY OF
THE LARAMIE AERODROME. DRY ELSEWHERE. FOR ALL AERODROMES...WINDS
GUSTING 20 TO 31 KNOTS 19Z MONDAY TO 01Z MONDAY EVENING IN THE
WELL MIXED ATMOSPHERE.

&&

.FIRE WEATHER...
ISSUED AT 234 PM MDT SUN MAY 12 2013

OUTSIDE OF A FEW SHOWERS OR THUNDERSTORMS OVER THE MOUNTAINS...IT
WILL BE DRY FOR THE REMAINDER OF THIS AFTERNOON WITH WARMER
TEMPERATURES AND BREEZY NORTHWEST SURFACE WINDS. HIGH PRESSURE AT
THE SURFACE AND ALOFT WILL EXPAND OVER THE DISTRICTS MONDAY
THROUGH TUESDAY. ISOLATED AFTERNOON SHOWERS OR THUNDERSTORMS WILL
BE POSSIBLE OVER THE MOUNTAINS MONDAY. WELL ABOVE NORMAL
TEMPERATURES ARE PREDICTED EARLY THIS WEEK FOR LOWER ELEVATIONS
WITH HIGHS IN THE 80S TO LOWER 90S. MINIMUM RELATIVE HUMIDITIES
BOTH DAYS WILL LOWER TO 10 TO 15 PERCENT... WITH POOR OVERNIGHT
RECOVERIES. WEST TO SOUTHWEST SURFACE WINDS WILL BECOME QUITE
GUSTY LATE MONDAY THROUGH TUESDAY AS A LOW PRESSURE SYSTEM MOVES
EAST ACROSS MONTANA. WITH FUELS READY TO BURN ACROSS THE WESTERN
NEBRASKA PANHANDLE...CRITICAL FIRE WEATHER CONDITIONS WILL BE
POSSIBLE ON TUESDAY. A COLD FRONT WILL MOVE FROM WEST TO EAST
THROUGH THE DISTRICTS TUESDAY AFTERNOON AND EVENING...WITH GUSTY
WINDS SHIFTING TO THE NORTHWEST.

&&

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

$$

UPDATE...LIEBL
SHORT TERM...JAMSKI
LONG TERM...FINCH
AVIATION...RUBIN
FIRE WEATHER...JAMSKI