000
FXUS65 KCYS 141744
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1144 AM MDT TUE MAY 14 2013

.UPDATE...
ISSUED AT 1106 AM MDT TUE MAY 14 2013

WEAK FRONT IS CURRENTLY MOVING ACROSS THE PLAINS WITH NORTH-TO-
NORTHEAST WINDS BEHIND IT. MANY LOCATIONS OVER THE PANHANDLE ARE
STARTING TO SEE RELATIVE HUMIDITY VALUES BELOW 15
PERCENT...HOWEVER SOUNDINGS CONTINUE TO SUGGEST THAT WINDS SHOULD
STAY WEAK (WITH GUSTS BELOW 20 MPH) AND THUS PREVENT RED FLAG
CRITERIA.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)

ISSUED AT 337 AM MDT TUE MAY 14 2013

CURRENTLY...COLD FRONT LAYS ACROSS EASTERN MONTANA...EXTENDING
WEST SOUTHWESTWARD THROUGH CENTRAL IDAHO THIS MORNING. NUMEROUS
LIGHTNING STRIKES BEING OBSERVED ACROSS EASTERN MONTANA THIS
MORNING. CLOSER TO HOME...GUSTY WINDS EARLY THIS MORNING HAVE KEPT
THE LOWER AIRMASS WELL MIXED WITH TEMPERATURES AT 1 AM THIS
MORNING IN THE UPPER 50S AND LOW 60S. EARLY MORNING HUMIDITIES
PRETTY LOW AS WELL IN THIS MIXED ENVIRONMENT WITH HUMIDITIES
BETWEEN 30 PERCENT IN OUR WIND PRONE AREAS TO 60 PERCENT OUT IN
THE PANHANDLE AND OUR MORE SHELTERED AREAS IN SOUTHEAST WYOMING.

ANOTHER ITEM OF INTEREST...THAT IS AND WILL HAVE SOME IMPACTS ON
OUR CURRENT AND UPCOMING WEATHER IS A PRETTY TIGHTLY WRAPPED
SHORTWAVE ON WATER VAPOR IMAGERY BEING OBSERVED NEAR SAN FRANCISCO
THAT IS COMING ON SHORE IN CENTRAL CALIFORNIA. IT APPEARS THAT
THIS SYSTEM MAY HAVE HAD SOME IMPACT ON FORECAST MID AND UPPER
LEVEL WINDS THIS MORNING AND HAS KEPT US FROM REALLY BLOWING LIKE
GUIDANCE WAS SHOWING FOR THIS TIME FRAME 24 HOURS AGO.

FOR TODAY...700MB TEMPERATURES VERY SIMILAR TO YESTERDAY...WITH
+12C FORECAST ACROSS THE AREA. TEMPERATURES ARE GOING TO BE VERY
SIMILAR TO YESTERDAYS HIGHS AND SEVERAL RECORD HIGHS FOR THIS DATE
ARE GOING TO BE TIED OR BROKEN. SEE CLIMATE SECTION BELOW FOR MORE
DETAILS. 700MB WINDS CONTINUE TO DECREASE THROUGH THE DAY AS THE
CALIFORNIA SHORTWAVE TRACKS INTO NEVADA. A DRY COLD FRONT LOOKS TO
DROP SOUTH AND SOUTHWEST OUT OF MONTANA AND SOUTH DAKOTA...LOOKING
TO MOVE INTO THE NORTHERN PANHANDLE AND NIOBRARA COUNTY BY 00Z AND
THEN TO THE EAST SLOPES OF THE LARAMIE RANGE BY 06Z TONIGHT.

BY WEDNESDAY MORNING...700MB TEMPERATURES DROP TO AROUND +8C AND
WE GET A LITTLE RELIEF FROM THE HOT TEMPERATURES WE HAVE HAD OVER
THE PAST COUPLE DAYS. THE CALIFORNIA SHORTWAVE LOOKS TO TRACK INTO
NORTHERN COLORADO DURING THE DAY WEDNESDAY. THE LATEST ECMWF...GFS
AND WRF MODELS ALL AGREE ON MOISTURE INCREASING WEDNESDAY MORNING
INTO THE AFTERNOON. PRECIPITABLE WATER VALUES OFF THE GFS SOUNDING
SHOWING NEAR .75 INCHES OF PWAT NEAR CHEYENNE HERE...WITH CLOSE TO
.6 INCHES OUT BY RAWLINS. COULD BE IN FOR DECENT SHOWERS AND
THUNDERSTORM COVERAGE WEDNESDAY AFTERNOON INTO THE EVENING HOURS.
WENT AHEAD AND INCREASED MOUNTAIN COVERAGE FOR SHOWERS/TSTMS FOR
THESE TIME FRAMES.

.LONG TERM...(THURSDAY THROUGH MONDAY)

ISSUED AT 337 AM MDT TUE MAY 14 2013

WEATHER FOR MUCH OF THIS PERIOD WILL BE AFFECTED BY AN UPPER TROF
THAT WILL MOVE SLOWLY EAST TOWARDS THE CWA THURSDAY AND FRIDAY
THEN PASS ACROSS IN TWO SEPARATE SHOTS SATURDAY THROUGH MONDAY.
WARM AND MAINLY DRY CONDITIONS EXPECTED THURSDAY AND FRIDAY AS
HEIGHTS RISE AHEAD OF THIS TROF THEN COOLING OFF OVER THE WEEKEND
WITH BETTER CHANCES FOR MAINLY SHOWERS. ECMWF MORE BULLISH WITH
QPF AND LOOKS SOMEWHAT OVERDONE THUS WILL LEAN MORE TOWARDS THE
SOMEWHAT DRIER GFS FOR NOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 1106 AM MDT TUE MAY 14 2013

VFR PREVAILS.

THROUGH 02Z TONIGHT...ISOLATED HIGH BASED SHOWERS AND THUNDERSTORMS
MAY AFFECT THE LARAMIE AND CHEYENNE TAFS WITH GUSTY AND ERRATIC
WINDS AS ISOLATED SHOWERS AND THUNDERSTORMS DEVELOP OVER AND NEAR
THE SNOWY...SIERRA MADRE AND SOUTHERN LARAMIE RANGES. SHOWERS
AND THUNDERSTORMS WILL PRODUCE LOCALIZED TURBULENCE.

PERIODS OF SCATTERED TO BROKEN LOW AND MIDDLE CLOUDS AT OR ABOVE
6000 FEET AGL.

A WEAK COLD FRONT WILL MOVE SOUTHWESTWARD TO THE LEE OF THE LARAMIE
RANGE THIS AFTERNOON AND THIS EVENING. SURFACE HIGH PRESSURE WILL
MOVE INTO SOUTH DAKOTA TONIGHT PRODUCING WEAK LOW LEVEL UPSLOPE
SOUTH AND SOUTHEAST WINDS ACROSS TAF SITES. LOW LEVEL SOUTH AND
SOUTHEAST WINDS WILL STRENGTHEN WEDNESDAY MORNING...WITH
SCATTERED CUMULUS AND TOWERING CUMULUS DEVELOPMENT ALONG AND
WEST OF INTERSTATE 25 BY LATE MORNING...ALONG WITH ISOLATED
THUNDERSTORMS IN THIS AREA TOWARDS NOON.

&&

.FIRE WEATHER...
ISSUED AT 337 AM MDT TUE MAY 14 2013

ANOTHER WARM AND DRY DAY ON TAP ACROSS SOUTHEAST WYOMING AND
NEBRASKA PANHANDLE. EXPECT AFTERNOON HUMIDITIES TO FALL INTO THE
LOW TO MID TEENS AREA WIDE AFTER A POOR OVERNIGHT RECOVERY THIS
MORNING. GOOD NEWS IS THAT PREVIOUSLY ANTICIPATED WINDS ARE
EXPECTED TO REMAIN NORTH OF OUR FORECAST AREA. STRONGEST WINDS ARE
EXPECTED TO OCCUR THIS MORNING WITH THE HIGHER MORNING
HUMIDITIES...THEN EXPECT A DECREASE IN WINDS THROUGH THE DAY.
WINDS WILL THEN SHIFT TO THE NORTH AND NORTHEAST LATE THIS
AFTERNOON ACROSS EAST CENTRAL WYOMING AND NEBRASKA PANHANDLE AS A
WEAK COLD FRONT SLIDES SOUTH TO THE EAST SLOPES OF THE LARAMIE
RANGE BY MIDNIGHT. COOLER TEMPERATURES WEDNESDAY EAST OF THE
LARAMIE RANGE WITH INCREASED DEWPOINTS. RAIN CHANCES BEGIN TO
INCREASE WEDNESDAY AFTERNOON AND EVENING ACROSS THE
MOUNTAINS AS ANOTHER PACIFIC DISTURBANCE MOVES INTO SOUTHERN
WYOMING. COULD SEE A PRETTY GOOD CHANCE FOR WETTING RAINS IN THE
SNOWY...SIERRA MADRE AND LARAMIE RANGES AS THIS OCCURS.

&&

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

$$

UPDATE...FINCH
SHORT TERM...CLAYCOMB
LONG TERM...RE
AVIATION...RUBIN
FIRE WEATHER...CLAYCOMB