321
FXUS65 KVEF 080355
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
855 PM PDT TUE OCT 7 2008
SYNOPSIS
DRY AND MILD CONDITIONS WILL CONTINUE THROUGH WEDNESDAY
BEFORE A SIGNIFICANT CHANGE BEGINS THURSDAY AND BECOMES MORE DRAMATIC
FRIDAY AND SATURDAY AS A STRONG LOW PRESSURE SYSTEM DIVES OUT OF
WESTERN CANADA AND INTO CENTRAL NEVADA. THIS SYSTEM WILL BRING
INCREASING WINDS THURSDAY FOLLOWED BY COLDER AND UNSETTLED WEATHER
THROUGH THE WEEKEND.
UPDATE
VERY LITTLE CHANGE TO THE 00Z NAM FROM THE PREVIOUS RUN
WITH VERY STRONG LOW FORMING AND DROPPING INTO THE GREAT BASIN
THURSDAY NIGHT INTO THE WEEKEND. WEDNESDAY WILL CONTINUE TO SEE
CLEAR SKIES WITH TEMPERATURES 4-6 DEGREES ABOVE NORMAL ACROSS MUCH
OF THE CWA. CURRENT FORECAST ON TRACK AND DO NOT PLAN ANY UPDATES
FOR THIS EVENING.
PREV DISCUSSION...335 PM PDT SHORT TERM
THE PLEASANT WEATHER OVER
THE REGION WILL PERSIST UNDER ZONAL FLOW THROUGH EARLY THURSDAY.
SOUTHWEST FLOW THEN INCREASES AS A DEEP TROUGH BEGINS TO TAKE SHAPE
OVER THE WESTERN STATES IN RESPONSE TO A BROAD COLD LOW SLIDING
SOUTH OUT OF THE GULF OF ALASKA AND BRITISH COLUMBIA. THE RECENT
RUNS OF THE NAM AND GFS NOW SUPPORT THE ECMWF WHICH HAS BEEN SHOWING
THIS PATTERN CHANGE FOR MORE THAN A FEW DAYS NOW. BREEZY CONDITIONS
WILL DEVELOP THURSDAY AFTERNOON AND TEMPERATURES MAY DROP A FEW
DEGREES...ESPECIALLY OVER CENTRAL NEVADA. DOWNSLOPE CONDITIONS COULD
POTENTIALLY DEVELOP OVER THE EAST SLOPES OF THE SOUTHERN SIERRA AS
NORTHWEST TO WEST RIDGETOP WINDS STRENGTHEN LATE THURSDAY THROUGH
EARLY FRIDAY.
LONG TERM
MODELS REMAIN IN EXCELLENT AGREEMENT WITH REGARDS TO
THIS WEEKENDS SYSTEM. A DEEP COLD LOW PRESSURE SYSTEM EXPECTED TO
DROP SOUTH OUT OF THE PACIFIC NORTHWEST FRIDAY MORNING WITH
INCREASING SOUTHWEST WINDS AHEAD OF A STRONG COLD FRONT. TIMING OF
THE FRONT IS STILL UNCERTAIN...BUT CURRENT THINKING IS THAT THE
FRONT WILL MOVE THROUGH THE CWA BETWEEN 00Z-12Z SATURDAY. STRONGEST
WINDS ARE LIKELY TO OCCUR OVER THE SOUTHERN CWA FRIDAY AFTERNOON
WITH THE POTENTIAL OF ADVISORIES/WARNINGS NEEDED. HOW MUCH MOISTURE
WILL BE AVAILABLE IS ANOTHER QUESTION. SINCE THIS LOW IS TAKING A
MORE INLAND APPROACH...NOT LOOKING FOR A SIGNIFICANT PACIFIC TAP.
HOWEVER THERE SHOULD BE ENOUGH DYNAMICS ASSOCIATED WITH THE LOW
CENTER TO GENERATE SCATTERED SHOWERS...MAINLY IN THE NORTHERN CWA.
EVEN WITH THE FRONT ITSELF A FEW SHOWERS ARE LIKELY TO DEVELOP...
BUT MAINLY OVER THE HIGHER ELEVATIONS. ANOTHER FACTOR WILL BE
TEMPERATURES. HIGH TEMPERATURES ARE FORECAST TO DROP 15 TO 20
DEGREES ON SATURDAY FROM THURSDAYS HIGHS AND ITS POSSIBLE THAT THE
LAS VEGAS VALLEY WILL REMAIN IN THE 60S FOR HIGHS. WITH LIGHTER
WINDS EXPECTED SUNDAY MORNING LOW TEMPERATURES MAY DROP INTO THE 40S
IN LAS VEGAS WITH BELOW FREEZING TEMPERATURES OVER THE NORTHERN CWA
AND THE HIGHER ELEVATION OF THE SOUTH. HIGH PRESSURE WILL START TO
REBUILD OVER THE AREA MONDAY WITH LIGHTER WINDS AND SLOWLY WARMING
TEMPERATURES...WHICH SHOULD CONTINUE THROUGH THE REMAINDER OF THE
EXTENDED PERIOD.
AVIATION...FOR MCCARRAN
CLEAR SKIES WITH LIGHT WINDS EXPECTED
THROUGH WEDNESDAY. SOUTHWEST WINDS WILL BEGIN TO INCREASE THURSDAY
AS A STRONG LOW PRESSURE SYSTEM APPROACHES THE AREA. BREEZY TO WINDY
CONDITIONS ALONG WITH A SLIGHT CHANCE OF SHOWERS CAN BE EXPECTED
FRIDAY AND FRIDAY NIGHT WITH THE APPROACH OF A STRONG COLD FRONT.
CURRENT THINKING IS THAT THE FRONT WILL MOVE THROUGH THE LAS VEGAS
VALLEY BETWEEN 00Z AND 08Z SATURDAY. HIGH TEMPERATURES ARE FORECAST
TO DROP AROUND 15 DEGREES BEHIND THE FRONT.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...CLEAR SKIES WITH GENERALLY LIGHT WINDS EXPECTED THROUGH
WEDNESDAY. AN APPROACHING LOW PRESSURE SYSTEM WILL START TO BRING A
CHANGE TO THE WEATHER BY THURSDAY. SOUTHWEST WINDS WILL INCREASE
OVER MOST AREAS THURSDAY AFTERNOON WITH BREEZY TO WINDY CONDITIONS
EXPECTED FRIDAY AND FRIDAY NIGHT AS A STRONG COLD FRONT MOVES
THROUGH THE REGION. ALONG WITH THE INCREASING WINDS...THERE WILL BE
A CHANCE OF RAIN AND HIGH ELEVATION SNOW SHOWERS LATE FRIDAY AND
SATURDAY OVER NORTHERN NYE...LINCOLN...AND ESMERALDA COUNTIES.
VEF WATCHES/WARNINGS/ADVISORIES
NV...NONE.
AZ...NONE.
CA...NONE.
JENSEN/ADAIR/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
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