####018003813####
FXUS65 KVEF 160405

AFDVEF



AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE LAS VEGAS NV

905 PM PDT SUN MAR 15 2009



.SYNOPSIS...DRY WEATHER CAN BE EXPECTED THROUGH MUCH OF THE UPCOMING 

WEEK...WITH TEMPERATURES WELL ABOVE NORMAL. THERE IS A CHANCE OF A 

STORM NEXT WEEKEND...WHICH WOULD BRING COOLER TEMPERATURES ALONG 

WITH CHANCES FOR MOUNTAIN SNOW AND VALLEY RAIN.

&&



.UPDATE...LEE ENHANCED CIRRUS BEGINNING TO INCREASE ACROSS THE 

NORTHERN PORTION OF THE CWA...BUT LITTLE ELSE EXPECTED OVERNIGHT. 

OVERALL CURRENT SHORT TERM FORECAST ON TRACK AND DO NOT PLAN ANY 

UPDATES FOR TONIGHT.

&&



.AVIATION...FOR MCCARRAN...SOUTH TO SOUTHWEST WINDS 4-8KTS THROUGH 

12Z MONDAY...BECOMING VARIABLE LESS THAN 8KTS THROUGH 06Z TUESDAY. 

GENERALLY CLEAR SKIES.



FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 

CALIFORNIA...VARIABLE WINDS LESS THAN 8KTS THROUGH 18Z MONDAY THEN 

SOUTHWEST 5-10KTS THROUGH 03Z TUESDAY. VARIABLE CLOUDS AOA 25K FT.

&&



.PREV DISCUSSION...342 PM PDT SHORT TERM...SATELLITE SHOWS CLEAR 

SKIES AREAWIDE THIS AFTERNOON. THE MAIN LOW PRESSURE AREA WAS 

SPINNING JUST OFFSHORE OF VANCOUVER ISLAND...WITH A STRONG JET 

ROTATING INTO OREGON PUSHING ANOTHER BATCH OF CLOUDS INTO NORTHERN 

CALIFORNIA AND NORTHERN NEVADA. THE SOUTHERN EDGE OF THESE CLOUDS 

WILL BRUSH OUR NORTHERN ZONES OVERNIGHT WHILE SKIES REMAIN MOSTLY 

CLEAR ELSEWHERE. VERY LITTLE OF CONCERN THROUGH THE SHORT TERM...AS 

THE OPERATIONAL MODELS AND ENSEMBLE MEMBERS AGREE ON THE JET STREAM 

SLOWLY RETREATING TO THE NORTH...ALLOWING FLAT RIDGING TO BUILD OVER 

OUR AREA. TEMPERATURES WILL RISE THROUGH THE SHORT TERM...WITH 

WEDNESDAY BEING THE MOST LIKELY DAY FOR THE FIRST 80F READING OF THE 

SEASON AT KLAS. HOWEVER...THE MODELS SHOW A WEAK DISTURBANCE MOVING 

TOWARD THE WEST COAST WEDNESDAY...WHICH COULD SPREAD A BLANKET OF 

CIRRUS OVERHEAD AND PUT A LID ON THE TEMPERATURE. TIME WILL TELL.



.LONG TERM...A WEAK UPPER LOW WILL MOVE EAST FROM THE PACIFIC ON 

THURSDAY AFTERNOON AND MOVE ACROSS SOCAL/SOUTHERN NEVADA THURSDAY 

NIGHT. THE ECMWF IS A BIT SLOWER EJECTING THIS FEATURE OUT ON 

FRIDAY...BUT MODEL CROSS SECTIONS CONTINUE INDICATE AN INCREASE IN 

MID AND HIGH LEVEL MOISTURE WITH THIS UPPER LOW AS IT MOVES THROUGH. 

TEMPERATURES WILL CONTINUE TO BE ABOVE NORMAL...THOUGH IF CLOUD 

COVER IS THICK ENOUGH IF IT MAY TEMPER AFTERNOON WARMING THEN.



A DEEP UPPER TROUGH IS SHOWN BY THE MODELS TO MOVE TOWARDS THE WEST 

COAST BY NEXT WEEKEND. HOWEVER THERE IS CONSIDERABLE DISAGREEMENT 

WITH RESPECT TO THE TIMING OF THIS FEATURE WITH IT POSSIBLY MOVING 

IN AS EARLY AS SATURDAY AFTERNOON OR AS LATE AS SUNDAY AFTERNOON. 

PER COORDINATION WITH SOME OF THE SURROUNDING WFO/S WE HAVE 

INTRODUCED POPS AS EARLY AS SATURDAY AFTERNOON WITH TIMING LEANED 

TOWARDS A BLEND OF THE ECMWF/GEM/GFS WHICH LEAVES IN POPS THROUGH 

NEXT SUNDAY NIGHT/MONDAY MORNING IN THE EAST. SNOW LEVELS WILL START 

OUT QUITE HIGH GIVEN THE WARM SOUTHWEST FLOW...AROUND 9K FEET...BUT 

LOWER TO AT LEAST 5K FEET BY SUNDAY EVENING OR WHENEVER THE TROUGH 

AXIS PASSES THROUGH. TEMPERATURES SHOULD DROP BACK TO AT LEAST 

NORMAL. THE OTHER BIG CONCERN WITH THIS SYSTEM WILL BE WINDS...AS A 

100 KNOT JET CROSSES THE AREA AND CAUSES STRONGER WINDS ALOFT TO MIX 

DOWN. MODELS SHOW 50 KT WINDS AS LOW AS 600 MB SO RIDGETOP WINDS 

WILL CERTAINLY BLOW. THAT SAID...DUE TO TIMING DIFFERENCES DID NOT 

GO QUITE THAT STRONG YET...AS IT IS STILL TOO EARLY TO PICK OUT JUST 

WHEN WE WILL GET THAT 5 TO 10 HOUR WINDOW OF STRONGER WINDS. 

&&



.VEF WATCHES/WARNINGS/ADVISORIES...

NV...NONE.

AZ...NONE.

CA...NONE. 

&&



$$



JENSEN/MORGAN/STACHELSKI



HTTP://WEATHER.GOV/LASVEGAS