Lake Wind Advisory 8, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
300 AM PDT MON SEP 3 2007

.SHORT TERM...
DEVELOPING LOW PRESSURE SYSTEM CURRENTLY SHOWING UP WELL ON
SATELLITE IMAGERY AROUND 135W 43N WITH STRONG UPPER JET DIVING TO
THE SOUTH BEHIND THE LOW. MODELS STILL CONSISTENT IN BRINGING THIS
LOW TO THE OREGON COASTLINE BY THIS EVENING BEFORE DIVING SOUTH TO
NRN CALIFORNIA OVERNIGHT AND THEN PASSING OVER NRN NV AS A DEEP
CLOSED LOW ON TUESDAY. THIS WILL BRING DRASTICALLY CHANGING WEATHER
CONDITIONS TO THE REGION WITH THE MAIN CONCERN BEING BREEZY WINDS
THE NEXT FEW DAYS. WINDS TODAY WILL BE STRONGEST NORTH OF INTERSTATE
80 AS AN ASSOCIATED COLD FRONT BEGINS TO SET UP OVER OREGON. WITH
INCREASED BOATING ACTIVITY DUE TO THE LABOR DAY HOLIDAY...FEEL THAT
LAKE WIND ADVISORIES ARE WARRANTED EVEN WITH MARGINAL WIND GUSTS
AROUND 30 MPH. DID HOWEVER PUSH THE TIMING OF THE LAKE WIND
ADVISORIES BACK TO THE AFTERNOON AS CONDITIONS IN THE MORNING
SHOULDNT BE TOO BAD.

WINDS INCREASE OVERNIGHT AS THE LOW MOVES ONSHORE AND GRADIENTS
TIGHTEN. SOME LOWER VALLEYS SHOULD DECOUPLE FROM THE WINDS HOWEVER
RIDGES AND FOOTHILLS WILL STAY BREEZY ALL NIGHT. MODELS HAVE
LIGHTENED UP A LITTLE ON WIND SPEEDS TUESDAY HOWEVER WITH STRENGTH
OF THE LOW AND THE COLD FRONT...STILL EXPECTING WIDESPREAD BREEZY
CONDITIONS. THE STRONGEST WINDS TUESDAY SHOULD BE ALONG THE SIERRA
FRONT FROM SUSANVILLE SOUTH TO THE MAMMOTH AREA...AND OVER THE GREAT
BASIN ZONES SOUTH OF INTERSTATE 80. WINDS IN THIS AREA SHOULD GUST
TO AROUND 40 MPH WITH THE POSSIBILITY FOR WIND ADVISORY CRITERIA
ALONG THE SIERRA FRONT. ANOTHER CONCERN WILL BE FOR BLOWING DUST IN
THE MOISTURE-STARVED GREAT BASIN ZONES. MODELS...MAINLY THE
NAM...STILL WANT TO GENERATE A GOOD AMOUNT OF MOISTURE AND
INSTABILITY OVER THE MONO-MINERAL CONVERGENCE ZONE TUESDAY AFTERNOON
WITH THE POSSIBILITY FOR THUNDERSTORMS. STILL BELIEVE THAT IT IS
OVERDONE AND STRONG WINDS ALOFT WILL SHEAR ANY DEVELOPMENT
APART...HOWEVER IT CANT BE IGNORED SO KEPT WITH SLIGHT CHANCE POPS
OVER THOSE AREAS. BETTER INSTABILITY MOVES INTO THE NRN ZONES LATE
TUESDAY AS THE COLD POOL MOVES OVERHEAD. WITH GOOD FORCING ALONG THE
FRONT AND DECENT JET DYNAMICS THE CHANCES ARE IMPROVING FOR SHOWERS
AND SOME EMBEDDED THUNDERSTORMS. RAISED THE POPS TO CHANCE CATEGORY
OVER THE FAR NORTH AND BROUGHT SLIGHT CHANCE POPS FURTHER SOUTH.

WINDS SHIFT TO THE NORTH TUESDAY NIGHT AND QUICKLY DECREASE AS THE
FRONT CONTINUES PASSING THROUGH THE AREA. MUCH COOLER TEMPERATURES
SETTLE IN TUESDAY NIGHT AND WEDNESDAY WITH READINGS LIKELY BACK
BELOW NORMAL. JORDAN

.LONG TERM...THURSDAY THROUGH SUNDAY...
HIGH PRESSURE OFF THE WEST COAST PRODUCES A LIGHT NORTHWEST FLOW
WITH DRY AND STABLE AIR OVER THE SIERRA AND WESTERN NV THURSDAY INTO
FRIDAY. THE AIRMASS DESTABILIZES JUST ENOUGH OVER THE CENTRAL SIERRA
FRIDAY AFTERNOON TO SEE A FEW CUMULUS CLOUDS. CLOUD COVER INCREASES
OVER SOUTHERN ZONES ON SATURDAY AS MID LEVEL CONVERGENCE DEVELOPS
BETWEEN A TROUGH DROPPING SOUTH THROUGH THE PAC NW AND A WEAK
DISTURBANCE MOVING NORTH ALONG THE SOUTHERN CA COAST. DO NOT EXPECT
THUNDERSTORM DEVELOPMENT AS INSTABILITY REMAINS MARGINAL HOWEVER
WILL LEAVE LOW POPS/NO WEATHER IN THE GRIDS. WILL ADD LOW POPS IN
NORTHERN ZONES ON SUNDAY AS THE LATEST GFS DROPS A VORT MAX INTO
NORTHEAST CA...A SOLUTION NOT SEEN IN THE ECMWF/CANADIAN MODELS
ALTHOUGH THE ECMWF DOES SHOW A MUCH WEAKER TROUGH MOVING INTO
EXTREME NORTHERN NV. THE GFS/ECMWF SOLUTIONS WOULD COOL DAYTIME
TEMPS SLIGHTLY OR AT LEAST KEEP THEM NEARLY STEADY OVER THE WEEKEND.
EITHER WAY THE FORECAST TEMPERATURES WILL REMAIN ABOVE SEASONAL
NORMALS...WHICH SEEMS APPROPRIATE AFTER SETTING RECORDS FOR HOT
WEATHER IN AUGUST AND OVER THE SUMMER SEASON. RC
&&

.AVIATION...
VFR CONDITIONS THROUGH TUESDAY MORNING. ISOLD TSTMS WITH BRIEF MVFR
CONDS AND OUTFLOW GUSTS TO 35 KT PSBL BTWN 21Z-03Z TODAY SOUTH OF
FALLON TO COLEVILLE LINE. RC
&&

.FIRE WEATHER...
BREAKDOWN OF THE UPPER RIDGE WILL OCCUR OVER THE NEXT FEW DAYS
BRINGING CRITICAL FIRE WEATHER CONDITIONS.

THE CONCERN TODAY WILL BE GUSTY WINDS AND LOW RHS MAINLY NORTH OF
INTERSTATE 80. GUSTS IN THIS AREA ARE EXPECTED TO BE 30-35 MPH AFTER
ABOUT 1400 HOWEVER RIDGES AND WIND PRONE AREAS MAY SEE GUSTS TO 40
MPH. LATEST MODEL RUNS HAVE CAUGHT ON TO THE DRY AIR OVER THE AREA
SO GETTING HUMIDITIES BELOW 15% SHOULD BE PRETTY EASY. AREAS WITH
HIGHER HUMIDITY WILL BE THE TAHOE BASIN AND WRN LASSEN COUNTY SO
THEY WILL CONTINUE TO STAY OUT OF THE RED FLAG WARNING...ALTHOUGH
ZONE 271 COULD BE CLOSE. MODELS ALSO HAVE HIGHER WINDS ALONG THE
SIERRA FRONT NOW SO WILL UPGRADE ZONE 450 TO THE RED FLAG WARNING AS
WELL.

WINDS ON MIDSLOPES AND RIDGES WILL STAY BREEZY ALL NIGHT HOWEVER
RHS SHOULD CLIMB ENOUGH TO BE OUT OF RED FLAG CATEGORY. SINCE
CONDITIONS ARE EXPECTED TO IMPROVE A LITTLE MONDAY NIGHT BEFORE
DETERIORATING AGAIN TUESDAY...WILL CONTINUE TO HANDLE THE 2 DAYS AS
SEPARATE EVENTS.

TUESDAY STILL LOOKS LIKE THE MOST CRITICAL DAY AS A STRONG COLD
FRONT PASSES FROM NORTH TO SOUTH ACROSS THE AREA. MODELS ARE STAYING
QUITE CONSISTENT WITH THIS EVENT SO THINKING IS STILL THE SAME AS
PREVIOUS SHIFTS. THE MOST CRITICAL AREA IS STILL EXPECTED TO BE
SOUTH OF INTERSTATE 80 INCLUDING THE SIERRA FRONT AROUND RENO. RHS
SHOULD STILL BE IN THE 10-15% RANGE IN THIS AREA...ESPECIALLY OVER
ZONES 453 AND 459...AND WIDESPREAD WIND GUSTS UP TO 40 MPH ARE
EXPECTED. RHS WILL BE ON THE RISE OVER THE LEESIDE VALLEYS NORTH OF
INTERSTATE 80...HOWEVER THE WIND CONCERN MAY BE HIGH ENOUGH TO
OVERCOME THE INCREASING HUMIDITY. ALSO A SIGNIFICANT WIND SHIFT FROM
SOUTHWEST TO NORTH IS EXPECTED IN THE 270-278-458 ZONES AROUND 1600
AS THE COLD FRONT MOVES THROUGH. WILL CONTINUE TO MONITOR THE
POTENTIAL FOR RED FLAG CONDITIONS IN THESE AREAS. RHS IN THE
CENTRAL AND NRN SIERRA SHOULD BE HIGH ENOUGH TO PREVENT CRITICAL
CONDITIONS FROM DEVELOPING. CONDITIONS WILL IMPROVE FROM NORTH TO
SOUTH TUESDAY NIGHT AS THE WINDS DECREASE AND COOLER TEMPERATURES
QUICKLY MOVE INTO THE AREA. JORDAN

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM PDT THIS
     EVENING FOR NVZ001-002-004.

     RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
     EVENING FOR NVZ450-458.

     FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
     FOR NVZ450-453-458-459.

CA...LAKE WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 9 PM PDT THIS
     EVENING FOR CAZ071>073.

     RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
     EVENING FOR CAZ270-278.

     FIRE WEATHER WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
     FOR CAZ273.

&&

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