Lake Wind Advisory 39, NWS Reno, NV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
1006 AM PDT MON JUL 6 2009

.FIRE WEATHER UPDATE...

FRESH 12Z MODEL GUIDANCE SHOWING NO MAJOR CHANGES TO WIND/RH
FORECAST FOR TUESDAY, THEREFORE WITH HIGH CONFIDENCE WILL UPGRADE
FIRE WEATHER WATCHES CURRENTLY IN EFFECT TUESDAY TO RED FLAG
WARNINGS. WILL ISSUE THESE SHORTLY TO GIVE MORE LEAD TIME. HAVE
COORDINATED THIS WITH AREA GACCS. GUSTS 30-40 MPH EXPECTED IN RFW
AREAS. AREAS IN FAR NE CA INTO NW NV (FIRE ZONES 458,270) LEFT OUT
DUE TO ANTICIPATED HIGHER MIN RH VALUES TUESDAY.

STRONG UPPER LEVEL JET SEEN IN BOTH GFS/ECMWF SOLUTIONS WILL DROP
INTO THE AREA TUESDAY, CONTINUING INTO WEDNESDAY. FIRST INSTINCT IS
TO LEAVE WATCH GOING FOR WED, BUT WILL LOOK INTO THAT MORE LATER
TODAY. NAM SHOWING WINDS EQUAL TO TUESDAYS, GFS LIGHTER, AND SREF
JOINT PROBABILITIES FOR WIND/RH NOT AS HIGH AS TUESDAY VALUES...SO
SOME UNCERTAINTY THERE. WITH JET IN THE AREA, RIDGES WILL CERTAINLY
CONTINUE BLOWING INTO OVERNIGHT HOURS TONIGHT AND TUES NIGHT...50+
MPH GUSTS LIKELY.

UPDATED FIRE WEATHER PRODUCTS OUT BY 11 AM PDT.

CS

.PUBLIC FORECAST UPDATE...

WITH WINDS ON SLIDE MTN ALREADY GUSTING ABOVE 50 MPH...HAVE MOVED
THE ONSET TIME OF THE LAKE WIND ADVY FORWARD TO 18Z TODAY. SOME
GUSTS OVER 20 KT HAVE ALREADY BEEN REPORTED IN THE TAHOE
BASIN...ALTHOUGH IT WILL TAKE AT LEAST ANOTHER HOUR FOR ADVISORY-
LEVEL CHOP TO SPREAD ACROSS THE LAKE. LAKE WIND ADVY WILL ALSO
ISSUED ON TUESDAY FOR ALL AREA LAKES AS THE STRONGER JET STREAM
MOVING OVERHEAD WILL PRODUCE FREQUENT GUSTS OF 35-40 MPH ACROSS
THE REGION. MJD

&&

.PREVIOUS DISCUSSION... /ISSUED 212 AM PDT MON JUL 6 2009/

.SHORT TERM...
SHELTERED VALLEY LOCATIONS HAVE MAINLY DECOUPLED THIS MORNING
HOWEVER RIDGES AND FOOTHILLS REMAIN QUITE BREEZY. THIS IS ALL
ATTRIBUTED TO AN UPPER SHORTWAVE SWINGING INTO THE OREGON
COASTLINE WHICH IS EMBEDDED IN A LONGWAVE TROUGH OVER THE ERN
PACIFIC. THIS TROUGH IS SLOWLY PUSHING THE WEST COAST RIDGE EAST
TOWARD THE DESERT SOUTHWEST WHICH IS TIGHENING GRADIENTS AND
BRINGING A PERSISTENT WIND PATTERN TO THE CWA. SLIDE MOUNTAIN
RECENTLY GUSTED TO 71 MPH AND SHOULD CURRENTLY BE MAXING OUT AS
THE SHORTWAVE STARTS EXITING THE AREA. H7 WINDS DROP OFF
SIGNIFICANTLY OVER THE NEXT 6-12 HOURS BEHIND THE SHORTWAVE SO
GUSTS TODAY WILL NOT BE OVERLY IMPRESSIVE...HOWEVER THE WINDS WILL
INCREASE MUCH EARLIER THAN THE LAST FEW DAYS. PROLONGED GUSTS OF
25-30 MPH ON LAKE TAHOE WILL CREATE SIGNIFICANT CHOP BY THIS
AFTERNOON SO WILL CONTINUE WITH THE LAKE WIND ADVISORY.

THE NEXT UPPER SHORTWAVE IS PROGGED TO MOVE INTO THE WEST COAST
DURING PEAK HEATING ON TUESDAY BRINGING THE WINDIEST PERIOD OF THE
FORECAST. GOOD UPPER JET SUPPORT COUPLED WITH TIGHT LOW LEVEL
GRADIENTS SHOULD SPELL WIDESPREAD GUSTS OF 30-40 MPH WITH HIGHER
GUSTS POSSIBLE IN WIND PRONE AREAS. THE MAIN CONCERN WITH THESE
WINDS WILL BE THE INCREASE IN FIRE POTENTIAL...SEE THE FIRE
WEATHER DISCUSSION BELOW...HOWEVER LAKE WIND ADVISORIES WILL ALSO
BE NEEDED FOR MOST AREA LAKES.

THE PATTERN DOES NOT CHANGE MUCH WEDNESDAY HOWEVER MODELS ARE AT
ODDS REGARDING PASSING UPPER SHORTWAVES. THE ANOMOLOUS LOW
CONTINUES OVER THE PACNW COAST SO THE POTENTIAL FOR BREEZY
CONDITIONS CONTINUES AS WELL. TEMPERATURES COOL OVER THE NEXT FEW
DAYS WITH VALUES AROUND 5 DEGREES BELOW NORMAL BY WEDNESDAY.
JORDAN

.LONG TERM...THURSDAY THROUGH SUNDAY...

MODELS IN GOOD AGREEMENT WITH TROUGH OVER THE PACIFIC NORTHWEST AND
FLAT RIDGE OVER THE FOUR CORNERS/SOUTHERN HIGH PLAINS.  SOLUTIONS A
BIT DIFFERENT FOR THE WEEKEND...IN KEEPING THE TROUGH ALONG THE
COAST AND NOT BUILDING THE RIDGE OVER THE EASTERN GREAT BASIN.

OVERALL GOOD CONFIDENCE IN A DRY AND BREEZY CONDITIONS...WITH NEAR
NORMAL TEMPERATURES INTO THE WEEKEND.  PATTERN IS FAVORABLE FOR PEAK
GUSTS OF 25-35 MPH WITH LOW TO VERY LOW AFTERNOON HUMIDITY.
THUNDERSTORM CHANCES BELOW 5 PERCENT ALL AREAS WITH DRY AND STABLE
SOUTHWEST FLOW. BRONG

&&

.AVIATION...

VFR CONDITIONS THIS WEEK. TROUGH WILL REMAIN OVER THE PACIFIC
NORTHWEST COAST AND PRODUCE AFTERNOON AND EVENING WIND GUSTS OF
25-35KTS 21Z-05Z.  35-55KT WINDS LIKELY OVER THE SIERRA RIDGES LATE
TUESDAY.  BRONG

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...RED FLAG WARNING FROM 11 AM TO 11 PM PDT TUESDAY FOR NVZ450-453-
     459.

     FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
     EVENING FOR NVZ450-459.

     LAKE WIND ADVISORY UNTIL 8 PM PDT THIS EVENING FOR NVZ002.

     LAKE WIND ADVISORY FROM 11 AM TO 8 PM PDT TUESDAY FOR NVZ002.

     LAKE WIND ADVISORY FROM 2 PM TO 8 PM PDT TUESDAY FOR NVZ004.

CA...RED FLAG WARNING FROM 11 AM TO 11 PM PDT TUESDAY FOR CAZ271>273-
     278.

     FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
     EVENING FOR CAZ273-278.

     LAKE WIND ADVISORY UNTIL 8 PM PDT THIS EVENING FOR CAZ072.

     LAKE WIND ADVISORY FROM 11 AM TO 8 PM PDT TUESDAY FOR CAZ072.

&&

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