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Area Forecast Discussion

000
FXUS65 KVEF 201010
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
309 AM PDT WED AUG 20 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA 
WILL ACT UPON MONSOON MOISTURE IN PLACE LEADING TO A CHANCE OF 
SHOWERS AND THUNDERSTORMS OVER SOUTHEAST CALIFORNIA...SOUTHERN 
NEVADA AND NORTHWEST ARIZONA THROUGH THURSDAY. ON FRIDAY ANY MENTION 
OF PRECIPITATION WILL BE CONFINED TO MOHAVE COUNTY. TEMPERATURES 
WILL WARM OVER THE WEEKEND BACK TO NEAR NORMAL.
&&

.SHORT TERM...THROUGH FRIDAY NIGHT
RADAR MUCH QUIETER FROM 24 HOURS AGO. WE ARE MONITORING MAINLY RAIN 
SHOWERS, ALTHOUGH EVER SO OFTEN ONE CELL WILL GENERATE A FEW 
LIGHTNING STROKES. 

CLOSED LOW JUST OFF THE SANTA BARBARA COAST WILL BE THE FEATURE OF 
INTEREST TODAY AND AGAIN THURSDAY. MODELS HAVE COME INTO GOOD 
AGREEMENT WITH THEIR HANDLING OF THE LOW THROUGH FRIDAY. CLOSED LOW 
WILL STAY ALONG OR JUST OFF THE SOUTHERN CALIFORNIA COAST TODAY. 
OUTSIDE OF SURFACE HEATING A STRENGTHENING JETSTREAK EAST OF THE LOW 
CUTTING OVER SOUTHEAST CALIFORNIA AND NORTHWEST ARIZONA WILL PROVIDE 
SOME ADDITIONAL LIFT. FOR SOUTHERN NEVADA, ADDITIONAL LIFT WILL 
OCCUR IN AN AREA OF DIFFLUENCE ALOFT WITHIN THE NORTHEAST QUADRANT 
OF THE CLOSED LOW. CLOSED LOW WILL MOVE AS FAR SOUTH AS SAN DIEGO 
TONIGHT BEFORE BEGINNING TO OPEN UP AND PICKUP SPEED AS IT SHOULD BE 
OVER THE LOWER COLORADO RIVER VALLEY BY LATE THURSDAY AFTERNOON. THE 
MOST SIGNIFICANT DIFFERENCE IN THE MODELS COMES ON THURSDAY WITH 
THEIR HANDLING OF MOISTURE ADVECTION OFF TROPICAL STORM LOWELL. NAM 
BY FOR THE MOST AGGRESSIVE WITH THIS TROPICAL CONNECTION ADVECTING 
MOISTURE FURTHER NORTH AND WEST INTO THE MOJAVE DESERT. GFS/ECMWF 
TAKE MUCH OF THIS MOISTURE NORTHEAST ACROSS ARIZONA. THAT IS 
SOMETHING WE WILL BE MONITORING VERY CLOSELY FOR SURE AS IT COULD 
HAVE A SIGNIFICANT AFFECT ON RAINFALL INTENSITY THURSDAY. ON  
THURSDAY NIGHT AND FRIDAY THE WEAKENING TROUGH WILL ACCELERATE EAST 
ACROSS ARIZONA AS A DEEPER /EARLY FALL-LIKE/ TROUGH DEVELOPS OVER 
THE PACIFIC NORTHWEST. MOISTURE WILL START TO BE SHUNTED EAST ON 
FRIDAY EXCEPT IN MOHAVE COUNTY WHERE I DID KEPT A SLIGHT CHANCE OF 
PRECIPITATION MENTIONED.                   

.LONG TERM...SATURDAY THROUGH WEDNESDAY NIGHT.

IN A MONTH THAT HAS LACKED ON BIG-TIME HEAT, WE APPEAR TO CATCH YET 
ANOTHER BREAK COME SATURDAY AS THE LATEST OPERATIONAL MODELS NOW DIG 
A DEEPER MID/UPPER LEVEL TROUGH NEVADA AND UTAH WITH THE BASE OF THE 
TROUGH EXTENDING ALL THE WAY INTO SOUTHERN NEVADA. THERE MAY STILL 
BE ENOUGH MID-LEVEL MOISTURE LEFT ACROSS THE EASTERN PORTIONS OF 
MOHAVE COUNTY FOR A SHOWER OR THUNDERSTORM TO POP UP ON SATURDAY, 
HOWEVER, A SHOWER OR THUNDERSTORM MAY ALSO POP UP IN THE AFTERNOON 
OR EVENING ACROSS THE LINCOLN COUNTY PANHANDLE IN ASSOCIATION WITH 
THE TROUGH AXIS. ONE CONCERN ON SATURDAY IS THAT MODELS MAY BE A 
LITTLE UNDERDONE WITH SURFACE WINDS GIVEN THE DEPTH OF THE TROUGH. 
WINDS WERE BUMPED UP SLIGHTLY ACROSS NORTHWESTERN SAN BERNARDINO 
COUNTY AS WELL AS OVER THE HIGHER TERRAIN OF THE SOUTHERN GREAT 
BASIN. THE MODELS SHOW A POOR ALIGNMENT OF THE WINDFIELDS WITH 
HEIGHT, BUT GIVEN THE DEPTH OF THE TROUGH PROGGED IT WOULD NOT BE A 
SURPRISE TO SEE FAVORED SPOTS GUST TO 25-35 MPH THEN. HIGHS SHOULD 
BE A DEGREE OR TWO WARMER THAN WHAT WE SEE ON FRIDAY.

TYPICAL OF EARLY SEASON COOL SEASON TROUGHS, THIS TROUGH APPEARS 
DEEP ENOUGH TO YIELD A SURFACE COLD FRONT PASSING THROUGH ACROSS THE 
NORTHERN HALF OF THE AREA SATURDAY NIGHT INTO SUNDAY MORNING WITH A 
WIND DIRECTION SHIFT NOTED. THE FRONT WILL LIKELY DAMPEN OUT BY THE 
TIME IT GETS AS FAR SOUTH AS LAS VEGAS, THOUGH A BRIEF WIND SHIFT TO 
THE NORTHWEST MAY TAKE PLACE INTO THE NW PART OF THE VALLEY THOUGH 
IT MAY BE JUST AS EASILY MASKED BY THE DIURNAL NATURE OF WINDS AT 
NIGHT. LOW TEMPS WERE LOWERED SEVERAL DEGREES CLOSER TOWARD THE 
ECMWF MOS. 

DRY NORTHWEST FLOW ALOFT LINGERS THROUGH TUESDAY AS A SECONDARY 
TROUGH AXIS SWIPES ACROSS UTAH. THIS WILL KEEP AWAY ANY MONSOON 
MOISTURE AND KEEP US UNDER ABUNDANT SUNSHINE OUTSIDE OF ANY CLOUDS 
THAT PUSH NEAR THE UTAH BORDER TUESDAY WITH THE NEXT TROUGH. LOW 
TEMPS WERE LOWERED SEVERAL DEGREES ACROSS THE NORTHERN CWFA WITH 
HIGH TEMPS SHOWING A WARMING TREND AREA-WIDE THOUGH TEMPERED. 
READINGS SHOULD RETURN ABOVE NORMAL BY TUESDAY. HOWEVER, NIGHTS WILL 
BE MUCH MORE COMFORTABLE GIVEN THE LOWER HUMIDITY AND LOWER READINGS 
OVERALL EVEN IN THE WARMER URBAN LOCATIONS IN THE MOJAVE DESERT. 
CERTAINLY A SIGN WE ARE GETTING CLOSER TO SAYING HELLO TO FALL. 
&&

.AVIATION...FOR MCCARRAN...CLOUDS AND ISOLATED RAIN SHOWERS WILL BE 
ON THE INCREASE FROM THE SOUTHWEST LATE THIS MORNING AND COULD 
PERSIST INTO THE AFTERNOON. ISOLATED THUNDERSTORMS WILL DEVELOP 
INTO ALL APPROACH CORRIDORS TODAY...WITH THE LOWEST CHANCE IN THE 
BEATTY CORRIDOR. WINDS WILL FAVOR A SOUTHEAST-SOUTH DIRECTION TODAY 
BUT WOULD BECOME GUSTY AND ERRATIC IN DIRECTION DUE TO NEARBY 
SHOWERS OR THUNDERSTORMS. 

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...ISOLATED/SCATTERED SHOWERS AND THUNDERSTORM WILL AFFECT 
AREAS ROUGHLY EAST OF A LINE FROM BARSTOW TO HIKO ON TODAY. WINDS 
WILL FAVOR A SOUTHEAST-SOUTH DIRECTION TODAY BUT WOULD BECOME GUSTY 
AND ERRATIC IN DIRECTION DUE TO NEARBY SHOWERS OR THUNDERSTORMS. 
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT INSTANCES OF 
FLASH FLOODING...STRONG GUSTY WINDS...HAIL...AND BLOWING DUST 
THROUGH WEDNESDAY.
&&

$$

SHORT TERM/AVIATION...PIERCE
LONG TERM...STACHELSKI

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