FXUS65 KVEF 230454
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
850 PM PST TUE DEC 22 2009

.SYNOPSIS...A STRONG LOW PRESSURE SYSTEM WILL RAPIDLY MOVE ACROSS 
THE AREA TONIGHT. THE SCATTERED SHOWERS AND GUSTY WINDS THAT 
ACCOMPANIED THIS SYSTEM...WILL DECREASE OVERNIGHT AS THE SYSTEM 
MOVES EAST. DRY WEATHER WILL THEN BE OVER THE REGION FOR THE REST OF 
THE WEEK AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE WEST COAST.
&&

.UPDATE...OVERALL THE SHORT TERM FORECAST IS ON TRACK...HOWEVER THE 
DETAILS WITHIN THE NEXT 6-12HRS ARE CONTINUING TO BE A PROBLEM. 
STRONG SURFACE PRESSURE GRADIENTS BETWEEN CENTRAL AND SOUTHERN 
NEVADA WILL BE SLOW TO DECREASE WITH CURRENT GRADIENT BETWEEN RENO 
AND LAS VEGAS AT 17.8 MBS. THIS WILL ALLOW NORTH WINDS TO CONTINUE 
THROUGH MUCH OF THE NIGHT BEFORE DECREASING DURING THE DAY ON 
WEDNESDAY. CURRENT WIND ADVISORY/HIGH WIND WARNINGS LOOK GOOD AND 
WILL ALLOW THEM TO CONTINUE THROUGH THE CURRENT EXPIRATION TIME OF 
MIDNIGHT PST. CURRENT THINKING IS THAT THEY WILL NOT NEED TO BE 
EXTENDED...AS WINDS SHOULD DECREASE TO BELOW ADVISORY LEVEL...BUT 
WILL CONTINUE TO MONITOR OVER THE NEXT FEW HOURS. AS THE STORMS 
CONTINUES TO SHIFT SOUTHEAST OVERNIGHT...SHOWERS TO BE ON THE 
DECREASE. A FEW SURPRISES HERE THOUGH AS A BAND OF MOISTURE HAS 
FORMED SHOWERS OVER WESTERN SAN BERNARDINO COUNTY THIS EVENING. 
CURRENT SATELLITE TRENDS SHOWS THAT THIS SHOULD BE ENDING BY LATE 
EVENING AS THE LOW DROPS TO THE SOUTH OF KLAS BY 06Z WED AND THEN TO 
THE ARIZONA/NEW MEXICO BORDER BY 12Z WED. ONCE AGAIN WILL BE 
MONITORING THE ENDING OF THE SHOWERS OVERNIGHT BUT TREND OF 
CONTINUING SHOWERS AFTER MIDNIGHT MAINLY OVER THE EASTERN PORTION OF 
THE CWA LOOKS GOOD. CURRENT ZONES LOOK GOOD BUT PLAN A LATE EVENING 
UPDATE TO ADDRESS WIND HEADLINES AND ANY NEEDED POP TRENDS.
$$    

.AVIATION...FOR MCCARRAN...NORTHWEST WINDS EXPECTED TO CONTINUE 
THROUGH MUCH OF THE NIGHT WITH SUSTAINED 15-20KTS AND GUSTS TO 
AROUND 30KTS BEFORE DECREASING AND BECOMING NORTHWEST 10-20KTS AFTER 
15Z WED. ISOLATED SHOWER STILL POSSIBLE THROUGH 08Z WED THEN SKIES 
TO CLEAR WITH FEW CLOUDS AOA 12K FT AFTER 12Z WED.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
CALIFORNIA...STRONG WEST WINDS GUSTING TO 60 KNOTS OR GREATER WILL 
PERSIST IN THE SAN BERNARDINO HIGH DESERT AREAS AND IN 
NYE/ESMERALDA/INYO COUNTIES FROM THE NORTH UNTIL ABOUT 07-08Z BEFORE 
SUBSIDING FOR THE REST OF THE NIGHT. RAIN AND SNOW SHOWERS
ARE POSSIBLE THROUGH LATE THIS EVENING IN SOUTHERN NEVADA AND 
EXTREME EASTERN CALIFORNIA. GRADUAL CLEARING WILL BEGIN LATE TONIGHT 
FROM WEST TO EAST AS THE STORM MOVES EAST OF THE AREA BY 18Z WED.
&&   

.PREV DISCUSSION...315 PM PST TUE SHORT TERM...MAIN UPPER LOW 
CURRENTLY DROPPING SOUTH THROUGH WESTERN NEVADA IS HELPING TO 
GENERATE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHERN 
INYO COUNTY. THIS AREA SHOULD CONTINUE TO WORK SOUTH AND THERE WILL 
BE A CHANCE OF SEEING ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS 
THIS EVENING...MAINLY SAN BERNARDINO...SOUTHERN CLARK AND SOUTHERN 
MOHAVE COUNTIES. WINDS DID MATERIALIZE THIS AFTERNOON AND SEVERAL 
LOCATIONS RECORDED GUSTS BETWEEN 50 AND 60 MPH WITH A COUPLE OVER 60 
MPH. WITH SURFACE PRESSURE GRADIENTS CONTINUING TO STRENGTHEN 
BETWEEN LAS/RNO EXPECT WINDS TO CONTINUE FOR THE NEXT FEW HOURS. 
WILL ALSO NEED TO WATCH THE AREA OF CONVECTION AS WINDS MAY END UP 
BEING EVEN STRONGER IN THE VICINITY OF THUNDERSTORMS. CURRENT HIGH 
WIND WARNINGS AND ADVISORIES LOOK GOOD. ALTHOUGH THERE WAS SOME SNOW 
IN LINCOLN COUNTY...THE LOCAL SHERIFF ONLY REPORTED AROUND AN INCH 
OF SNOW WITH NO PROBLEMS ON THE ROADS. DID GO AHEAD AND CANCEL THE 
WINTER WEATHER ADVISORY FOR LINCOLN COUNTY. ALTHOUGH A COUPLE OF 
INCHES WILL BE POSSIBLE THIS EVENING. THE LOW IS FORECAST TO 
CONTINUE TO DROP SOUTHEAST AND BE OVER CENTRAL ARIZONA BY WEDNESDAY 
MORNING. STILL EXPECT TO SEE SOME ISOLATED SHOWERS ACROSS MOHAVE AND 
SOUTHERN LINCOLN COUNTIES...BUT ARE EXPECTED TO REMAIN LIGHT. ALL 
PRECIPITATION SHOULD BE OVER BY THE AFTERNOON. A NORTHERLY FLOW WILL 
OCCUR WEDNESDAY WHICH WILL HELP KEEP TEMPERATURES BELOW NORMAL. 
WINDS WILL ALSO DECREASE ACROSS THE AREA...WITH THE EXCEPTION OF THE 
COLORADO RIVER VALLEY WHERE LOCALLY BREEZY CONDITION WILL REMAIN. 
HIGH PRESSURE WILL BUILD TO THE WEST WEDNESDAY NIGHT AND THURSDAY 
BRINGING LIGHTER WINDS AND SLOWLY WARMING TEMPERATURES. 

.LONG TERM...SATURDAY THROUGH TUESDAY...RIDGING WILL STILL BE OVER 
THE AREA SATURDAY FOR ANOTHER TRANQUIL DAY BEFORE THE PATTERN AGAIN 
BECOMES PROGRESSIVE AND ACTIVE. SUNDAY WILL SEE THE FIRST WAVE COME 
INTO THE COAST AND CALIFORNIA BRINGING PRECIPITATION INTO THE 
SIERRA. THOUGH MODELS DIFFER IN THE EXACT TRACK...THEY TAKE IT SOUTH 
THROUGH CALIFORNIA AND OUR WESTERN CWA BEFORE IT BOTTOMS OUT NEAR 
THE CA-NV-AZ JUNCTURE MONDAY AND THEN EJECTS EAST. HAVE KEPT THE 
BULK OF THE POPS IN THE WESTERN AND SOUTHERN PARTS OF THE CWA THEN 
AND DID INCREASE THEM A LITTLE. RIDGING FOLLOWS QUICKLY TUESDAY 
AFTER THE SYSTEMS EXIT BEFORE ANOTHER AND POSSIBLY STRONGER SYSTEM 
COMES INTO THE PICTURE THURSDAY.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...WIND ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR NVZ017.
     HIGH WIND WARNING UNTIL MIDNIGHT PST TONIGHT FOR NVZ014.
AZ...NONE.
CA...WIND ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR CAZ519>522.
     HIGH WIND WARNING UNTIL MIDNIGHT PST TONIGHT FOR CAZ523>526.
&&

$$

JENSEN/GORELOW/JACQUES

HTTP://WEATHER.GOV/LASVEGAS