Lake Wind Advisory 2, NWS Las Vegas, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
935 AM PST TUE FEB 13 2007

.SYNOPSIS...A PACIFIC STORM SYSTEM MOVING INTO CALIFORNIA TODAY WILL
PRODUCE A CHANCE OF HEAVY SNOW OVER PARTS OF THE SOUTHERN GREAT
BASIN...AND A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOJAVE DESERT.
THE STORM WILL MOVE THROUGH THE DESERT SOUTHWEST AND EXIT TO THE
EAST WEDNESDAY...ENDING THE CHANCES FOR RAIN AND SNOW. A RIDGE OF
HIGH PRESSURE WILL BRING DRY AND WARMER WEATHER THROUGH THE REST OF
THE WEEK...AND POSSIBLY INTO THE WEEKEND.
&&

.UPDATE...COOLING OF CLOUD TOPS ON IR IMAGERY COMPARES WELL WITH
AREA OF ENHANCED FRONTOGENESIS IN THE 850-700MB LAYER. THIS BAND IS
FORECAST TO SAG SOUTH DURING THE DAY. FARTHER SOUTH A SURFACE
CONVERGENCE ZONE EXTENDS ACROSS NORTHWEST ARIZONA AND FAR SOUTHERN
NEVADA WITH THE SURFACE LOW IN THE VICINITY OF LAKE MEAD. MID-LEVEL
COOLING ASSOCIATED WITH NEGATIVE TILT UPPER TROUGH WILL ASSIST IN
DESTABILIZING THE AIR MASS THIS AFTERNOON AND COULD SUPPORT ISOLATED
THUNDERSTORM DEVELOPMENT OVER LINCOLN...CLARK AND MOHAVE COUNTIES.
CURRENT FORECAST PACKAGE HAS THE SITUATION COVERED WELL SO NO
UPDATES PLANNED.

.SHORT TERM...SATELLITE SHOWS MAIN STORM OVER NORTHERN CALIFORNIA
EARLY THIS MORNING...WITH A VORTICITY LOBE ROTATING INTO SOUTHERN
CALIFORNIA. AHEAD OF THE STORM...BROAD SCALE ASCENT WAS NOTED OVER
OUR CWFA...WITH CLOUDS BEGINNING TO COOL AND ENHANCE. A BAND OF
HEAVY SNOW...INCLUDING THUNDERSNOW...DEVELOPED LATE IN THE EVENING
OVER WHITE PINE AND NORTHERN NYE COUNTIES...JUST NORTH OF OUR CWFA
BOUNDARY. NAM AND GFS STILL INSIST THAT THE AREA OF BEST LIFT WILL
SAG SOUTH DURING THE DAY INTO LINCOLN AND CENTRAL NYE COUNTIES...SO
WILL LEAVE THE SNOW ADVISORY IN PLACE. NEARLY NEUTRAL STATIC
STABILITY OVER MUCH OF THE CWFA BY AFTERNOON AS COLDER AIR ALOFT
MOVES IN SHOULD ALSO LEAD TO A SLIGHT CHANCE OF THUNDER. AS THE
STORM EXITS TO THE EAST THIS EVENING AND TONIGHT...DEVELOPING
NORTHERLY FLOW WILL FLUSH OUT THE MOISTURE AND PRECIP CHANCES FROM
NORTHWEST TO SOUTHEAST. THE NORTHERLY FLOW WILL INCREASE ON
WEDNESDAY...AND THE FINER RESOLUTION MODELS ARE GETTING A LITTLE
MORE BULLISH WITH WINDS DOWN THE COLORADO RIVER BY THE AFTERNOON.
STILL LOOKS BELOW ADVISORY CRITERIA...BUT WILL HAVE TO WATCH AND SEE
IF THE TREND CONTINUES. THE GRADIENT WILL RELAX ON THURSDAY AS A
DIRTY RIDGE BUILDS IN AND BRINGS TEMPERATURES BACK TO NORMAL FOR
THIS TIME OF YEAR.

.LONG TERM...HIGH PRESSURE OVER THE AREA FRIDAY STARTS OFF THE
EXTENDED PERIOD. THIS WILL BRING ABOVE NORMAL TEMPERATURES TO THE
REGION THEN. MAIN CONCERN FOR THE EXTENDED IS THE APPROACH AND
PASSAGE OF A LOW OPENING INTO A TROUGH FROM THE SOUTH ON SUNDAY. GFS
AND ECMWF HAVE BACKED OFF ON THE AMOUNT OF CLOUDS AND PRECIPITATION
FOR SUNDAY. IF MODELS PERSIST IN THIS EVOLUTION NEXT FORECAST MAY
NEED TO DECREASE THE POPS THEN. STILL LOOKING AT ANOTHER PACIFIC
SYSTEM TO START EXERTING ITS INFLUENCE EARLY NEXT WEEK.
&&

.AVIATION...FOR KLAS: SUBSTANTIAL CLOUD COVER WILL PERSIST OVER THE
LAS VEGAS VALLEY AND ALL APPROACH CORRIDORS FOR MOST OF THE DAY.
SCATTERED RAIN SHOWERS CAN BE EXPECTED IN THE AREA THROUGH THIS
EVENING WITH CEILINGS LOWERING TO AROUND 5000 FT AT TIMES. THERE IS
ALSO A SLIGHT CHANCE OF THUNDERSTORMS WITHIN 25 MILES OF THE AIRPORT
DURING THE AFTERNOON. CLEARING IS EXPECTED OVERNIGHT WITH A NORTH
WIND OF 10-15 KTS DEVELOPING WEDNESDAY.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA: CLOUD COVER WILL PERSIST TODAY. CEILINGS WILL BE AS LOW
AS 1500 FT AGL IN LINCOLN...ESMERALDA...AND CENTRAL NYE COUNTIES
ALONG WITH PERIODS OF MODERATE SNOW. THE ENTIRE AREA WILL SEE
CLEARING FROM NORTH TO SOUTH OVERNIGHT.

&&

.VEF WATCHES/WARNINGS/ADVISORIES...
.NV...SNOW ADVISORY UNTIL 4 PM ZONES 14-15.
.AZ...NONE.
.CA...NONE.
&&

RUNK/GORELOW

HTTP://WEATHER.GOV/LASVEGAS