NOAA


MODIS AFD Archive Index
Last updated July 22, 2008
Area Forecast Discussions
mentioning
MODIS
issued by
National Weather Service Forecast Office
Las Vegas, Nevada (VEF)

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

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