Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 210253 CCA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
753 PM PDT MON APR 20 2015

.SYNOPSIS...A SERIES OF SYSTEMS WILL PASS NEAR OR ACROSS THE AREA
THROUGH SATURDAY RESULTING IN THE POSSIBILITY OF SHOWERS AND
THUNDERSTORMS. ACTIVITY WILL BE CONFINED TO THE HIGHEST ELEVATIONS
THROUGH TUESDAY. FOR WEDNESDAY THROUGH FRIDAY THE CHANCE OF SHOWERS
AND THUNDERSTORMS WILL SPREAD ACROSS THE ENTIRE AREA. TEMPERATURES
WILL REMAIN SLIGHTLY ABOVE NORMAL THROUGH WEDNESDAY THEN LOWER TO
SEVERAL DEGREES BELOW NORMAL FOR THURSDAY AND FRIDAY.
&&

.UPDATE...THERE WAS JUST ENOUGH OF A MOIST LAYER CENTERED MAINLY
AROUND 500 MB TO ALLOW FOR QUITE OF A BIT OF CUMULUS CLOUD
DEVELOPMENT THIS AFTERNOON. HOWEVER, WITH THE ATMOSPHERE REMAINING
CAPPED IT WAS TOUGH FOR THE CLOUDS AROUND TO DO MUCH WITH RESPECT TO
VERTICAL GROWTH OR TRIGGER PRECIPITATION. THE EXECPTION HAS BEEN
ACROSS THE WHITE MOUNTAINS, THE INYO RANGE AND THE WEST SLOPES OF
THE SOUTHERN SIERRA WHERE SOME SHOWERS DID DEVELOP. I DID AN UPDATE
TO THE FORECAST TO REMOVE ANY SHOWERS/THUNDERSTORMS FROM THE SPRING
MOUNTAINS AND SHEEP RANGE AND TRIM BACK POPS A BIT IN PARTS OF
WESTERN INYO COUNTY. ANY SHOWERS AROUND SHOULD END IN THE NEXT FEW
HOURS WITH CLOUDS GRADUALLY CLEARING OUT OVERNIGHT WITH THE LOSS OF
HEATING.

.AVIATION...FOR MCCARRAN...SOUTH/SOUTHWEST DRAINAGE WINDS UP TO 10
KNOTS ARE EXPECTED THROUGH THE OVERNIGHT HOURS. CUMULUS CLOUDS AT
ABOUT 12 KFT WILL LINGER THROUGH 06Z TUESDAY. LIGHT AND VARIABLE
WINDS TUESDAY MORNING SHOULD BECOME SOUTHEASTERLY 8-12 KTS  TUESDAY
AFTERNOON WITH CUMULUS AND ISOLATED SHOWERS/THUNDERSTORMS DEVELOPING
OVER THE MOUNTAINS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...EXPECT MAINLY DIURNAL WIND TRENDS AT ALL TAF SITES
THROUGH TONIGHT. GENERALLY CLEAR SKIES FROM KDAG-KEED THROUGH
TUESDAY. ELSEWHERE EXPECT CUMULUS DEVELOPMENT AND ISOLATED
SHOWERS/THUNDERSTORMS OVER THE MOUNTAINS THROUGH 05Z TUESDAY AND
AGAIN TUESDAY AFTERNOON AND EVENING. GUSTY AND ERRATIC WINDS ARE
POSSIBLE IN AND NEAR ANY SHRA/TSRA.
&&

.PREVIOUS DISCUSSION...
ISSUED AT 300 PM PDT MON APR 20 2015

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT.

WEAK INSTABILITY...DEFORMATION AND MID LEVEL MOISTURE ASSOCIATED
WITH AN UPPER LOW OFF THE COAST WILL CONTINUE TO LEAD TO ISOLATED
MOUNTAIN SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING AND
AGAIN TUESDAY AFTERNOON AND EVENING AS THE LOW MOVES JUST INLAND.
SHOWER AND THUNDERSTORM CHANCES WILL INCREASE A BIT WEDNESDAY AS THE
LOW WEAKENS AND ROTATES NORTHEAST INTO SOUTHERN NEVADA AS A SECOND
LOW DROPS DOWN OFF THE SOUTHERN CALIFORNIA COAST. MOISTURE DOES NOT
APPEAR TO BE ABUNDANT BUT THERE IS JUST ENOUGH MOISTURE AND FORCING
TO JUSTIFY MENTIONING A CHANCE OF SHOWERS AND THUNDERSTORMS IN MOST
AREAS. THE SECOND LOW WILL THEN TRACK NORTHEAST ACROSS SOUTHERN
CALIFORNIA INTO ARIZONA WEDNESDAY NIGHT AND THURSDAY. IT LOOKS LIKE
THERE WILL BE A DRY SLOT OF SORTS BETWEEN THE TWO LOWS LATE
WEDNESDAY AND WEDNESDAY NIGHT BUT MOISTURE SHOULD INCREASE AGAIN
THURSDAY LEADING TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
AREA WIDE. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL
LINGER INTO THURSDAY EVENING BUT SHOULD DECREASE OVERNIGHT AS THE
LOW WEAKENS AND MOVES EAST TO THE FOUR CORNERS REGION.

.LONG TERM...FRIDAY MORNING THROUGH SUNDAY.

AT THE BEGINNING OF THE LONG TERM PERIOD THE UPPER AIR PATTERN WILL
FEATURE OUR THURSDAY UPPER LOW/TROUGH EXITING TO THE EAST, WITH ONLY
A SLIGHT PERIOD OF SHORTWAVE RIDGING OVERHEAD. THE SMALL RIDGE AXIS
WILL QUICKLY PUSH EAST AS ANOTHER SHORTWAVE TROUGH APPROACHES FROM
THE NORTHWEST. THERE REMAIN DIFFERENCES BETWEEN THE MODELS ON THE
STRENGTH OF THIS NEXT WAVE. EITHER WAY, IT WILL MEAN ANOTHER CHANCE
OF SHOWERS FOR MAINLY THE HIGHER ELEVATIONS OF NORTHERN INYO COUNTY,
SOUTHERN NEVADA, AND NORTHERN MOHAVE COUNTY FRIDAY AND AGAIN
SATURDAY. WOULD ONLY EXPECT SHOWERS IN THE VALLEYS IF THERE IS
PROPAGATION OFF THE TERRAIN. EXPECTING MAINLY SHOWERS, BUT COULD SEE
AN ISOLATED STORM ACROSS THE SIERRA AND PORTIONS OF ESMERALDA COUNTY
FRIDAY. THE MID-LEVEL TROUGH AXIS WILL SLIDE ACROSS THE REGION
SATURDAY, WITH A RIDGE BUILDING IN FROM WEST TO EAST SATURDAY NIGHT
THROUGH SUNDAY. AS THE RIDGE BUILDS IN, SHOWER CHANCES WILL COME TO
AN END. THE RIDGE WILL HOLD STRONG THROUGH MONDAY, ALTHOUGH FLOW
ALOFT WILL TRANSITION TO SOUTHWESTERLY AS ANOTHER TROUGH NEARS THE
WEST COAST. TEMPERATURES WILL BE COOLEST AT THE BEGINNING OF THE
PERIOD, NEAR NORMAL. THEN, AS HIGH PRESSURE BUILDS IN, TEMPERATURES
WILL QUICKLY WARM FOR SUNDAY AND MONDAY.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT ACCORDING TO
STANDARD OPERATING PROCEDURES.
&&

$$

UPDATE/AVIATION...STACHELSKI
SHORT TERM...HARRISON
LONG TERM...PADDOCK

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