000 FXUS65 KVEF 012256 AFDVEF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 256 PM PST SAT MAR 01 2008 .SYNOPSIS...A COLD FRONT WILL MOVE THROUGH THE GREAT BASIN TONIGHT BRINGING BLUSTERY NORTH WINDS AND COOLER TEMPERATURES FOR SUNDAY. && .SHORT TERM...SURFACE COLD FRONT WAS JUST MOVING THROUGH TONOPAH AND ONTO THE NORTHERN PART OF THE NEVADA TEST SITE AT 3 PM. THE FRONT IS EXPECTED TO INTENSIFY AS IT MOVES THROUGH CENTRAL NEVADA OVERNIGHT. PRESSURE GRADIENT DOES SHOW SIGNS OF INCREASING BETWEEN RNO AND LAS AS WELL AS THE LAX TO LAS CORRIDOR. PRE-FRONTAL DOWNSLOPE WINDS DID NOT PENETRATE INTO THE OWENS VALLEY AS WE ORIGINALLY ANTICIPATED. HOWEVER...SIERRA ROTORS SITE 1 DID RECORD A 61 MPH GUST FROM THE WEST IN THE PAST HOUR...AND SITE 4 WHICH IS AT A LOWER ELEVATION REPORTED A 45 MPH WESTERLY GUST. THESE ARE PROBABLY ASSOCIATED WITH PASSAGE OF THE UPPER TROUGH AXIS WHICH IS CROSSING THE AREA NOW. PROBABLY SHOULD HAVE WAITED FOR THE TROUGH TO PASS THE CREST BEFORE CANCELING THE WARNING BUT TOO LATE NOW. AT THIS POINT IT IS DOUBTFUL WE WILL SEE WARNING LEVEL WIND GUSTS ANYWAY BUT WE ARE CLEARLY GETTING SOME ENHANCEMENT OF THE WEST WINDS ALONG THE LEE SLOPES. THE 1-KM MODIS IMAGERY FROM EARLY THIS MORNING DEPICTED SHARP WAVE BREAKING FROM MONO COUNTY DOWN TO THE NORTHERN HALF OF INYO COUNTY BUT VERIFYING OBSERVATIONS WERE LIMITED TO MONO. GUSTY SOUTHWEST WINDS AHEAD OF THE SYSTEM PRODUCED DEEP MIXING TO ENHANCE THE WARM SIDE OF THE BAROCLINIC ZONE BUT THAT EFFECT HAS TAPERED OFF FOR THE PAST COUPLE HOURS DUE TO THICK LAYER OF MIDDLE AND HIGH CLOUD COVER. THAT SAME SHIELD OF CLOUDS HAS ALSO INHIBITED ANY MODIFICATION OF THE COOL SIDE OF THE BAROCLINIC ZONE THOUGH. AS A RESULT...THE INHERITED WARNINGS AND ADVISORIES APPEAR TO BE ON TRACK. TOMORROW WILL BE WINDY AND SUBSTANTIALLY COOLER ACROSS MOST OF THE FORECAST AREA. .LONG TERM...STILL SOME QUESTION ABOUT THE SYSTEM ON WEDNESDAY...BUT IT LOOKS LIKE BOTH THE GFS/ECMWF HAVE TRENDED SLIGHTLY WEAKER AND FARTHER EAST. THE 18Z GFS IS STILL SHOWING THE POTENTIAL OF BREEZY CONDITIONS WEDNESDAY AFTERNOON THROUGH THURSDAY AS SURFACE HIGH PRESSURE SETS UP OVER SOUTHERN IDAHO/NORTHERN UTAH. THE 12Z ECMWF HAS ALSO TRENDED WEAKER AND INSTEAD OF CLOSING A LOW OFF OVER SOUTHWEST ARIZONA...IT IS NOW MUCH FURTHER SOUTH. IT ALSO KEEPS THE MAJORITY OF THE COLDER AIR EAST OF OUR AREA AND IT LOOKS LIKE WE WILL NOT SEE MUCH OF A COOLING TREND. FOR THE REMAINDER OF THE EXTENDED PERIOD THE MODELS ARE SHOWING A COUPLE OF WEAK SYSTEMS PUSHING THROUGH NORTHERN NEVADA...BUT OUR AREA SHOULD REMAIN DRY WITH TEMPERATURES SLIGHTLY ABOVE NORMAL. && .AVIATION...FOR MCCARRAN...SOUTHWEST WINDS 14-24 KNOTS WILL CONTINUE THROUGH 03Z AHEAD OF A STRONG COLD FRONT THAT IS CURRENTLY SWEEPING THROUGH NEVADA. THE FORECAST TIME FOR FRONTAL PASSAGE STILL LOOKS TO BE AROUND 04Z-06Z THIS EVENING. WINDS WILL SWITCH TO THE NORTH AND INCREASE TO AROUND 25-35 KNOTS WITH POTENTIAL GUSTS NEAR 50 KNOTS FOR ABOUT 2 HOURS AFTER PASSAGE. WINDS WILL REMAIN IN THE 360-020 DIRECTION THROUGH SUNDAY WITH SPEEDS IN THE 14-24 KNOT RANGE AND GUSTS AROUND 30 KNOTS. A FEW CLOUDS AROUND 10K FEET AGL WITH CIGS ABV 15K FEET EXPECTED THROUGH TONIGHT. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...A COLD FRONT IS CURRENTLY PUSHING THROUGH CENTRAL NEVADA WITH SOUTHWEST TO WEST WINDS 20-30 KNOTS AHEAD OF THE FRONT. THE FRONT WILL PUSH INTO EXTREME SOUTHERN NEVADA BY 12Z SUNDAY MORNING WITH STRONG NORTHERLY WINDS BEHIND THE FRONT. WITHIN 1-2 HOURS OF FRONTAL PASSAGE NORTH WINDS ARE LIKELY TO INCREASE INTO THE 25-35 KNOT RANGE WITH POTENTIAL GUSTS NEAR 50 MPH. WINDS MAY BE STRONGER DOWN THE COLORADO RIVER DUE TO THE STEEPER NORTH/SOUTH CHANNELS. NORTH WINDS WILL CONTINUE THROUGH SUNDAY WITH MINIMAL CLOUD COVER. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...HIGH WIND WARNING UNTIL 4 PM PST SUNDAY FOR NVZ014-015-017>019. HIGH WIND WARNING FROM 4 AM TO 7 PM PST SUNDAY FOR NVZ021. RED FLAG WARNING FROM 10 AM TO 7 PM PST SUNDAY FOR NVZ466. WIND ADVISORY UNTIL 4 AM PST SUNDAY FOR NVZ021. WIND ADVISORY UNTIL 7 PM PST SUNDAY FOR NVZ016-020-022. AZ...HIGH WIND WARNING FROM 5 AM TO 8 PM MST SUNDAY FOR AZZ002-036. RED FLAG WARNING FROM 11 AM TO 8 PM MST SUNDAY FOR AZZ101. WIND ADVISORY UNTIL 5 AM MST SUNDAY FOR AZZ002-036. WIND ADVISORY UNTIL 8 PM MST SUNDAY FOR AZZ001-003. CA...HIGH WIND WARNING UNTIL 4 PM PST SUNDAY FOR CAZ522. HIGH WIND WARNING FROM 4 AM TO 7 PM PST SUNDAY FOR CAZ527. RED FLAG WARNING FROM 10 AM TO 7 PM PST SUNDAY FOR CAZ229. WIND ADVISORY UNTIL 4 AM PST SUNDAY FOR CAZ523-527. WIND ADVISORY UNTIL 7 PM PST SUNDAY FOR CAZ524-526. $$ RUNK/GORELOW HTTP://WEATHER.GOV/LASVEGAS ----------------------------------------------------------------------
