459
FXUS65 KVEF 030914
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
215 AM PDT THU OCT 3 2013

.SYNOPSIS...A STRONG COLD FRONT WILL MOVE THROUGH THE REGION THIS
AFTERNOON BRINGING INCREASED WINDS TODAY AND EVEN STRONGER WINDS
FRIDAY. LOCAL GUSTY WINDS ARE ALSO POSSIBLE SATURDAY...ESPECIALLY IN
THE COLORADO RIVER VALLEY. MUCH COOLER TEMPERATURES ARE EXPECTED
FRIDAY AND SATURDAY BEFORE A WARMING TREND BEGINS SUNDAY AND EARLY
NEXT WEEK.
&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...BACK EDGE OF CLOUDS
ROLLING THROUGH LINCOLN COUNTY EARLY THIS MORNING WITH THE REMAINDER
OF THE CWA UNDER MOSTLY CLEAR SKIES. WE SHOULD SEE A FEW HIGH CLOUDS
FROM TIME TO TIME TODAY...BUT THEY SHOULD HAVE NO EFFECT ON
AFTERNOON TEMPERATURES. UPPER LOW CURRENTLY OVER IDAHO THIS MORNING
WILL GRADUALLY TRACK SOUTHEAST TODAY AND DRAG A COLD FRONT THROUGH
THE CWA TODAY. ALTHOUGH WE WILL SEE SOME INCREASE IN SOUTHWEST WINDS
AHEAD OF THE FRONT THE STRONGEST WINDS ARE EXPECTED BEHIND THE FRONT
WHICH WILL ROLL INTO THE NORTHERN AREAS OF THE CWA AROUND MID DAY
AND EVENTUALLY INTO THE FAR SOUTHERN AREAS BY EARLY EVENING. EXPECT
A QUICK SHOT OF HIGHER WINDS BEHIND THE FRONT AS IT MOVES THROUGH
ESMERALDA...CENTRAL NYE AND LINCOLN COUNTIES WITH WIND GUSTS
APPROACHING 40 MPH. HOWEVER...DO NOT THINK THE DURATION WILL BE LONG
ENOUGH...3 HOURS OR MORE...TO WARRANT A WIND ADVISORY FOR THOSE
AREAS AS WINDS SHOULD START DECREASING AND REMAIN GENERALLY BETWEEN
20-30 MPH THROUGH FRIDAY. AS THE FRONT PUSHES INTO THE LAS VEGAS
VALLEY...THINK THAT WE MAY SEE SOME ISOLATED GUSTS OVER 40 MPH OVER
THE EASTERN HALF OF THE VALLEY ESPECIALLY NEAR NELLIS AND OVER
PORTIONS OF HENDERSON...BUT AGAIN THESE GUSTS ARE NOT EXPECTED TO
LAST VERY LONG AND WILL GENERALLY START TO DECREASE WITH WIDESPREAD
20-30 MPH WINDS. HOWEVER...AS THE FRONT PUSHES FURTHER SOUTH TOWARD
THE COLORADO RIVER VALLEY I DO EXPECT MUCH STRONGER AND AND A LONGER
DURATION OF HIGHER WIND SPEEDS. WENT AHEAD AND ISSUED A WIND
ADVISORY FOR PORTIONS OF THE SOUTHERN CWA WITH AN EMPHASIS ON THE
COLORADO RIVER VALLEY WHERE WINDS MAY GUST OVER 40 MPH FOR A MUCH
LONGER PERIOD STARTING THIS EVENING. ANOTHER CONCERN WILL BE FOR THE
PAHRUMP VALLEY WHERE WE MAY SEE A REVERSE DOWNSLOPE EVENT OFF THE
SPRING MOUNTAINS AS THE FRONT PUSHES THROUGH. ITS POSSIBLE THAT
WINDS MAY GUST CLOSE TO 50 MPH OVER PORTIONS OF PAHRUMP FRIDAY NIGHT
AND HAVE ELECTED TO ISSUED A WIND ADVISORY TO COVER THIS.

COOLER TEMPERATURES ARE ON TAP FOR TODAY AS COOLER AIR WILL ADVECT
INTO THE REGION AHEAD OF THE FRONT...BUT ARE REALLY EXPECTED TO
TUMBLE ON FRIDAY AS MUCH COOLER AIR FILTERS INTO THE AREA. READINGS
TODAY WILL BE AROUND 5-10 DEGREES COOLER THAN YESTERDAY AND AROUND
15-20 DEGREES COOLER ON FRIDAY. NOT MUCH IN THE WAY OF PRECIPITATION
WITH THIS SYSTEM AND OTHER THAN A FEW CLOUDS CONDITIONS WILL REMAIN
DRY.

.LONG TERM...SATURDAY THROUGH THURSDAY. MODELS HAVE COME INTO BETTER
AGREEMENT WITH HIGH AMPLITUDE RIDGE BUILDING IN BEHIND THE DEPARTING
STORM. ON SATURDAY...OUR AREA WILL BE UNDER NORTHERLY FLOW IN
BETWEEN THE TWO SYSTEMS...SO NORTH WINDS WILL CONTINUE DOWN THE
COLORADO RIVER VALLEY AND ANOTHER ADVISORY MAY BE NEEDED. ON SUNDAY
THE BIG RIDGE MOVES OVERHEAD...WITH WINDS SUBSIDING AND TEMPERATURES
JUMPING UP SEVERAL DEGREES TO NEAR NORMAL. BY MONDAY...THE NEXT
STORM SHOULD BE REACHING THE PACIFIC NORTHWEST...AND MODEL
DIFFERENCES START TO INCREASE. THE ECMWF SHOWS THE STORM DIGGING
SOUTHWARD MUCH MORE VIGOROUSLY...ESPECIALLY FROM TUESDAY ONWARD. BY
WEDNESDAY FORECAST CONFIDENCE GOES TO ZERO WITH 500 MB HEIGHT
SPREADS OF 100-150 M OVER MUCH OF OUR AREA. THE OPERATIONAL GFS
SHOWS WEAK TROUGHING AND DRY CONDITIONS...WHILE THE OPERATIONAL
ECMWF SHOWS A DEEP CLOSED LOW OVERHEAD WITH CLOUDS AND POSSIBLY
SHOWERS. ENSEMBLES ARE OF LITTLE HELP WITH TWO DISTINCT CAMPS
CLUSTERED AROUND THE TWO OPERATIONAL SOLUTIONS. GRIDS WILL BE CLOSER
TO THE GFS...WITH DRY WEATHER AND 5-10 DEGREES OF COOLING...BUT WILL
NEED TO CONTINUE TO MONITOR.
&&

.AVIATION...FOR MCCARRAN...SOUTH WINDS AT 8-14 KTS WITH OCCASIONAL
GUSTS TO 20 KTS CONTINUE THROUGH 16Z THEN BECOME LIGHT AND VARIABLE.
WINDS ARE EXPECTED TO REMAIN LIGHT AND VARIABLE THROUGH EARLY
AFTERNOON. BETWEEN 00Z-03Z TODAY...A STRONG COLD FRONT WILL MOVE
ACROSS THE VALLEY TURNING WINDS TO THE NORTH WITH GUSTS OF 20-30 KTS
POSSIBLE. NORTHERLY WINDS AT 12-18 KTS WITH GUSTS TO 25 KTS WILL
CONTINUE FOR MUCH OF FRIDAY. FEW CLOUDS AOA 25K FT THROUGH THE
PERIOD.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...A STRONG COLD FRONT WILL PUSH SOUTH ACROSS THE AREA
TODAY...REACHING BISHOP AND TONOPAH LATE THIS MORNING...THE LAS
VEGAS AREA DURING THE LATE AFTERNOON...THEN NEEDLES BY ROUGHLY 04Z.
NORTH WINDS GUSTING TO 25-40 KTS WILL BE POSSIBLE BEHIND THIS FRONT.
THESE NORTH WINDS SHOULD CONTINUE FRIDAY DOWN THE COLORADO RIVER
VALLEY...WITH GUSTS OF 35-40 KTS POSSIBLE THROUGH FRIDAY AFTERNOON.
FEW-SCT CLOUDS AOA 25K FT THROUGH THE PERIOD.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...WIND ADVISORY FROM 8 PM THIS EVENING TO 5 PM PDT FRIDAY FOR
     NVZ021-022.
     WIND ADVISORY FROM 8 PM THIS EVENING TO 5 AM PDT FRIDAY FOR
     NVZ017.
AZ...WIND ADVISORY FROM 8 PM THIS EVENING TO 5 PM MST FRIDAY FOR
     AZZ002-036.
CA...WIND ADVISORY FROM 8 PM THIS EVENING TO 5 PM PDT FRIDAY FOR
     CAZ524-526-527.
&&

$$

GORELOW/MORGAN/STUMPF

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