AREA FORECAST DISCUSSION

 
 FXUS65 KVEF 211756 AAA
 AFDVEF
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE LAS VEGAS NV
 955 AM PST SAT NOV 21 2009
 
 .SYNOPSIS...THE REGION WILL BE UNDER A DRY NORTHWEST FLOW THROUGH 
 MONDAY. SOME HIGH CLOUDS WILL DRIFT THROUGH FROM TIME TO TIME AND 
 LOCALLY GUSTY NORTH WINDS ARE POSSIBLE TODAY AND AGAIN ON SUNDAY 
 NIGHT AND MONDAY AS UPPER LEVEL DISTURBANCES BRUSH THE AREA. 
 TEMPERATURES WILL BE FAIRLY CLOSE TO NORMAL THROUGH MONDAY.
 &&
 
 .UPDATE...WEAK FRONTAL BOUNDARY MOVED THROUGH MCCARRAN AIRPORT 
 BETWEEN 8 AND 9 AM. FRONT WILL CONTINUE TO SLOWLY WORK SOUTH THIS 
 MORNING BEFORE WASHING OUT ACROSS SOUTHERN MOHAVE AND SAN BERNARDINO 
 COUNTY THIS AFTERNOON. TEMPERATURES WILL BE SEVERAL DEGREES COOLER 
 BEHIND THE FRONT TODAY. IN MORNING UPDATE WILL MASSAGE THE WINDS AND 
 REMOVE THE MENTION OF MORNING.
 &&     
 
 .AVIATION...FOR MCCARRAN...THIS MORNINGS FRONTAL PASSAGE HAS BROUGHT 
 THE WINDS OVER TO THE NORTHWEST. THEY SHOULD REMAIN 10 KNOT OR LESS 
 TODAY AND GRADUALLY VEER OVER TO THE NORTHEAST LATER IN THE 
 AFTERNOON. THIS EVENING AND OVER NIGHT THEY WILL GO TO THE 
 SOUTHWEST. ANY CLOUD COVER WILL REMAIN FEW TO SCATTERED AND ABOVE 
 20KFT.
 
 FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
 CALIFORNIA...THE MAIN CONCERN TODAY ARE WINDS...AS A WEAK COLD FRONT 
 PASSES THROUGH THE AREA TODAY. STRONG SOUTHWESTERLY WINDS CAN BE 
 EXPECTED PREFRONTAL...WITH WINDS DECREASING AND SWITCHING TO THE 
 NORTH BEHIND THE FRONT. ANY CLOUD COVER WILL REMAIN FEW TO SCATTERED 
 IN COVERAGE AND ABOVE 20KFT.
 &&
 
 .PREV DISCUSSION...250 AM PST SAT NOV 21...UPPER TROUGH WHICH 
 BROUGHT WINDY CONDITIONS TO MANY AREAS YESTERDAY AND LAST NIGHT WILL 
 MOVE EAST OF THE AREA TODAY. GUSTY SOUTHWEST WINDS HAVE BEEN 
 DROPPING OFF EARLY THIS MORNING AND WILL CANCEL/EXPIRE THE WIND 
 ADVISORIES. SOME LOCALLY GUSTY NORTH WINDS ARE POSSIBLE IN A FEW 
 AREAS TODAY BEHIND THE TROUGH BUT NOTHING NEAR ADVISORY CRITERIA. 
 TEMPERATURES TODAY ARE TRICKY TO FORECAST AS CURRENT TEMPERATURES 
 ARE WAY UP BUT COOLING WAS EXPECTED BEHIND THE TROUGH. RAISED 
 INHERITED TEMPS UP A BIT TO ACCOUNT FOR THE WARM START TO THE DAY 
 AND GENERALLY WENT WITH A COMPROMISE BETWEEN AVN AND NAM12 MOS 
 GUIDANCE. DRY NORTHWEST FLOW CONTINUES SUNDAY AS ANOTHER TROUGH 
 MOVES INTO IDAHO AND NORTHEAST NEVADA. MAIN MOISTURE WITH THIS 
 SYSTEM WILL STAY NORTH AND JUST EXPECT SOME HIGH CLOUDS. DRY 
 NORTHWEST FLOW WILL PERSIST MONDAY BUT TEMPERATURES MAY BE A FEW 
 DEGREES COOLER BEHIND THE AFOREMENTIONED TROUGH AND A REINFORCEMENT 
 OF NORTHERLY WINDS WHICH COULD BE A LITTLE GUSTY...ESPECIALLY DOWN 
 THE COLORADO RIVER VALLEY. 
 
 .LONG TERM...MODELS REMAIN IN GOOD AGREEMENT UP THROUGH THANKSGIVING 
 DAY...SO MINIMAL CHANGE WAS NEEDED TO THE EXISTING FORECAST. THE 
 GEM...GFS...AND ECMWF ALL INDICATE RIDGING ACROSS THE AREA THROUGH 
 THE MIDDLE OF THE WEEK...RESULTING IN TEMPERATURES SLIGHTLY ABOVE 
 NORMAL BY MID WEEK AND LIGHT WINDS PREDOMINANTLY OUT OF THE NORTH 
 DURING THE LATE MORNING AND AFTERNOON AS THE SURFACE HIGH PERSISTS 
 ACROSS THE NORTHERN GREAT BASIN. THERE ARE STILL MAJOR DIFFERENCES 
 IN GUIDANCE NEXT FRIDAY AND BEYOND...WITH THE GFS INDICTING RIDGING 
 AND THE EC AND GEM SHOWING A RATHER DEEP TROUGH. DECIDED TO PLAY THE 
 CLIMO CARD THIS FAR OUT...BUT IF THE GEM/EC SOLUTION SHOW ANY 
 CONTINUITY...AND MORE GFS ENSEMBLE MEMBERS TREND THAT WAY...WILL 
 DEFINITELY HAVE TO DROP TEMPERATURES AND INCREASE POPS BY THE END OF 
 NEXT WEEK AND INTO THE WEEKEND.
 &&
 
 .VEF WATCHES/WARNINGS/ADVISORIES...
 NV...NONE.
 AZ...NONE.
 CA...NONE.
 &&
 
 

 
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