High Wind in Nevada, April 19, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
343 PM PDT SAT APR 19 2008

.SHORT TERM...
A LARGE COLD LOW PRESSURE SYSTEM OVER THE PACIFIC NORTHWEST IS
DRIVING A COLD FRONT SOUTH ACROSS THE CWA THIS AFTERNOON. WITH
THE FRONT PUSHING SOUTH ACROSS THE CWA TONIGHT AND WITH A 110
KNOT JET STREAM OVERHEAD...THE STRONG SURFACE WINDS SHOULD LAST
UNTIL AROUND 10 PM NORTH OF HIGHWAY 50 WHILE MONO AND MINERAL
COUNTIES WILL SEE THE WINDS PERSIST BEYOND MIDNIGHT.

THERE IS SOME UNCERTAINTY IN HOW MUCH PRECIPITATION WILL RESULT
BEHIND THE COLD FRONT TONIGHT. THE NAM SHOWS A NARROW BAND
DEVELOPING NEAR TAHOE AND EXTENDING NORTHEAST TOWARDS LOVELOCK
THIS EVENING...STAYING NORTH OF THE RENO/SPARKS/CARSON CITY AREA.
THE GFS KEEPS THE PRECIP MUCH FARTHER NORTH WHILE THE HIGHER
RESOLUTION WRF KEEPS PRECIP NORTH OF A SUSANVILLE TO GERLACH LINE
EXCEPT FOR A SMALL AREA THAT DEVELOPS NEAR THE SIERRA CREST AROUND
LAKE TAHOE THIS EVENING AND PERSISTS FOR 3 OR 4 HOURS. HAVE
PRIMARILY GONE WITH THE DRIER WRF/GFS SOLUTIONS SINCE THE AIRMASS
IS EXTREMELY DRY (DEW POINTS AS LOW AS MINUS 5 F IN WESTERN NV
VALLEYS)...AND RADAR/SATELLITE SHOW LITTLE SUPPORT FOR ANY
SIGNIFICANT PRECIP TO THIS POINT.

MUCH COLDER AIR SPREADS ACROSS THE AREA OVERNIGHT AND SUNDAY. IT
SEEMS THAT THE MAV GUIDANCE IS VERY WARM FOR RENO ON SUNDAY WITH A
PROJECTED HIGH OF 51 (SAME AS FWC GUIDANCE). THIS DESPITE THICKNESS
VALUES REMAINING BELOW 540 DM THROUGH SUNDAY. THE MET GUIDANCE WITH
HIGHS IN THE LOWER 40S SUNDAY IS MORE REASONABLE AND WILL CONTINUE
TO BE USED FOR HIGH TEMPERATURE FORECASTS THROUGH THE SHORT TERM.

RELATIVE HUMIDITIES PLUMMETED ACROSS MANY AREAS TODAY AND WILL
LIKELY FALL SHARPLY IN MONO AND MINERAL COUNTIES THIS EVENING. HAVE
TRIMMED BACK RHS TONIGHT ESPECIALLY SOUTH ZONES AS RECOVERIES
SHOULD BE VERY POOR IN THE WELL MIXED LOWER LEVELS.

ISOLATED SHOWERS SHOULD AGAIN BE CONFINED TO THE NORTHERN PORTIONS
OF THE CWA SUNDAY WITH DRY CONDITIONS OVER NEARLY ALL OF THE CWA
MONDAY. AN OMEGA BLOCK IN THE GULF OF ALASKA GETS UNDERCUT BY A
LOW WHICH PHASES WITH THE PAC NW SYSTEM ON MONDAY AND TUESDAY. A
SHORTWAVE ROTATING THROUGH THIS SYSTEM MOVES TO NORTHERN CA BY
TUESDAY NIGHT AND BRINGS AT LEAST A SLIGHT CHANCE OF SHOWERS TO
ALL ZONES TUESDAY NIGHT WITH HIGHEST POPS IN THE EASTERN CA ZONES.
RC

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
THE 12Z DATA SEEMS TO BE COMING CLOSER TO A CONSENSUS SOLUTION WITH
THE LONGWAVE PATTERN INTO NEXT WEEKEND. OVERALL THE TROF AFFECTING
THE REGION FROM TUES-WED IS BEING CARRIED THRU THE REGION A LITTLE
FASTER...RESULTING IN WEDNESDAY MORE LIKELY TO HAVE ONLY LINGERING
SHOWERS MAINLY IN THE MORNING. POPS WERE SCALED BACK A BIT ON
WEDNESDAY TO POSSIBLY ESTABLISH A DRYING TREND BUT SOME MORE RUN TO
RUN CONSISTENCY WOULD BE NEEDED IN THE GUIDANCE BEFORE MAKING A MORE
SUBSTANTIAL REDUCTION IN POPS.

RIDGE IS NOW MORE LIKELY TO REBUILD OFF THE WEST COAST ON THURSDAY
THEN PROGRESS EASTWARD INTO NEXT WEEKEND AS ANOTHER TROF APPROACHES
THE NWRN US-SWRN CANADA COAST. THE GFS IS FASTEST WITH THIS INLAND
PROGRESSION...INDICATING THE AXIS ALREADY INTO ERN NV BY MIDDAY
FRIDAY...WHILE THE ECMWF AND CANADIAN ARE ABOUT A DAY BEHIND WITH
THIS RIDGE POSITION. EVEN WITH THESE DIFFERENCES...THE GAP HAS
NARROWED IN COMPARISON TO PREVIOUS ECMWF AND GFS DATA SO CONFIDENCE
IS IMPROVING WITH TRACKING THIS RIDGE. ALL OF THESE SCENARIOS WILL
KEEP DRY WEATHER OVER THE REGION...WITH THE MAIN UNCERTAINTY
INVOLVING MAX TEMPS AND AFTERNOON WINDS. IN GENERAL A BLEND OF THE
LATEST ECMWF AND GFS SOLUTIONS WAS APPLIED TO THE REMAINDER OF THE
EXTENDED PERIOD...TRENDING MAX TEMPS UPWARD A FEW DEGREES FOR
THURS-FRI WITH SOME VALLEYS RECOVERING TO AROUND 70 DEGREES BY
FRIDAY. TEMPS MAY DROP SLIGHTLY BY SATURDAY AS 500 MB HEIGHTS
DECREASE BUT IMPROVED MIXING AND LIMITED CLOUD COVER SHOULD DELAY
ANY SUBSTANTIAL COOLING. MJD

&&

.AVIATION...
WINDS WILL BE THE PRIMARY AVIATION CONCERN THRU TONIGHT AS GUSTS TO
40 KT REMAIN A THREAT THRU 03Z FOLLOWED BY GRADUAL DECREASE IN WINDS
OVERNIGHT. SOME MINOR DIRECTIONAL OR SPEED SHEAR MAY BE ENCOUNTERED
WHILE APPROACHING THE KRNO AIRPORT THRU 03Z...BUT OVERALL WINDS IN
THE LOW LEVELS SHOULD REMAIN RELATIVELY CONSISTENT IN DIRECTION
AND SPEED SO IT IS UNLIKELY THAT THE KRNO TAF WILL NEED A WS GROUP.
HOWEVER...PILOT REPORTS WILL CONTINUE TO BE MONITORED DURING THE
NEXT FEW HOURS. FOR KLOL...SO FAR TODAY VSBY HAS RANGED FROM 3-7 SM
IN BLDU BUT OCCASIONAL DECREASES TO NEAR 1 SM ARE LIKELY THRU 04Z AS
WIND DIRECTION TRENDING TOWARD THE WEST AND NORTHWEST WILL INCREASE
THE AMOUNT OF BLDU IN THE VICINITY.

MOISTURE IS SPARSE BUT POTENTIAL STILL EXISTS FOR A NARROW BAND OF
-SHSN TO DEVELOP IN THE POST FRONTAL AIR MASS AS JET STREAK ALOFT
GENERATES STRONG DYNAMICS THIS EVENING. THE POTENTIAL FOR THIS -SN
IS GREATER AT KTRK WHERE CIGS/VSBY MAY DROP TO IFR FOR AN HOUR OR
TWO BETWEEN THE 03Z-07Z TIME WINDOW. THE SNOW POTENTIAL DIMINISHES
FOR KTVL...AND DROPS EVEN FURTHER FOR KRNO-KLOL WHERE THE MORE
LIKELY RESULT IS A NEAR-MVFR CEILING.

FOR SUNDAY...VFR CONDS WILL PREVAIL ACROSS THE REGION WITH W-NW WIND
GUSTS TO 25 KT THROUGHOUT THE DAY. MJD
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR NVZ002>004.

     HIGH WIND WARNING UNTIL 5 AM PDT SUNDAY FOR NVZ001.

CA...WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CAZ072.

     HIGH WIND WARNING UNTIL 5 AM PDT SUNDAY FOR CAZ073.

&&

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