Special Weather Statement, NWS Reno, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
208 PM PDT FRI JUL 15 2011

.SHORT TERM...
WEAK TROF OFF THE WEST COAST WILL SWING INLAND THIS
EVENING...KEEPING A THREAT OF ISOLD-SCT TSTMS OVER THE REGION.
THE COMBINATION OF EAST WINDS AND SSW WINDS ALONG THE SIERRA CREST
HAS ALLOWED SOME CUMULUS TO FORM NEAR THE CARSON RANGE WITH SOME
CELLS TRYING TO FORM NEAR THE DOUGLAS-ALPINE COUNTY LINE. PRIMARY
AREAS OF INSTBY THRU LATE AFTN INCLUDE THE SIERRA FROM TAHOE SOUTH
TO MONO COUNTY...AND ALSO FROM NERN CA TO NWRN NV WITH GENERAL
CELL MOVEMENT MAINLY TO THE NORTH. HIGH RESOLUTION MODEL OUTPUT IS
HINTING THAT SOME CELLS COULD BUILD BACK TO NEAR THE RENO-SPARKS
VICINITY BTWN 22Z-01Z...WITH A FEW STRONG CELLS POSSIBLE AS
OUTFLOWS INTERACT WITH LOW-MID LEVEL CONVERGENCE AFTER RIDGE WINDS
AT SLIDE MTN SHIFT TO THE SOUTHWEST.

BY THIS EVENING...THE FORCING FROM RENO-TAHOE SOUTHWARD IS
EXPECTED TO WEAKEN BUT LINGER FOR A FEW MORE HOURS FARTHER NORTH
WHICH WILL BE IN CLOSER PROXIMITY TO THE MAIN TROF. ELEVATED
INSTBY WITH 500-300 MB LAPSE RATES NEAR 7.5 C/KM IN PORTIONS OF
NWRN NV WILL KEEP THE POSSIBILITY OF A FEW TSTM CELLS GOING THRU
EARLY SAT MORNING.

FOR THE REMAINDER OF THE WEEKEND AND INTO MONDAY...LONGWAVE TROF
IS EXPECTED TO BECOME RE-ESTABLISHED OFF THE WEST COAST AND KEEP
MODERATE SSW FLOW ALOFT OVER THE SIERRA AND WRN NV. WITH THE UPPER
LEVEL JET EXPECTED TO BE TOO FAR EAST AND DYNAMICS ASSOCIATED WITH
THE OFFSHORE TROF TOO FAR WEST...MOISTURE AND INSTBY DO NOT APPEAR
TO BE SUFFICIENT FOR PRODUCING ANY TSTMS.

THE PRESENCE OF THIS TROF WILL ALSO KEEP DAYTIME TEMPS A FEW
DEGREES BELOW NORMAL WITH ONLY THE LOWER VALLEYS NEAR AND EAST OF
HWY 95 EXPECTED TO SURPASS 90 DEGREES. ZEPHYR-TYPE BREEZES
GUSTING NEAR 30 MPH ARE EXPECTED THRU THE WEEKEND...PRODUCING SOME
CHOP ON TAHOE BUT BASED ON RECENT DAYS WITH SIMILAR WINDS THE
OVERALL CONDITIONS SHOULD REMAIN JUST BELOW LAKE WIND CRITERIA. A
SLIGHT INCREASE IN GUST SPEED AND DURATION OF AFTERNOON WINDS IS
PROBABLE BY MONDAY AS SFC PRESSURE AND 700 MB THERMAL GRADIENTS
TIGHTEN A BIT. MJD

.LONG TERM...TUESDAY THROUGH FRIDAY...
500MB HEIGHTS TO INCREASE TUESDAY AND WEDNESDAY AS THE PAC NW TROUGH
WEAKENS AND RIDGING OVER THE SW US BUILDS INTO THE FORECAST AREA. THIS
WILL KEEP TEMPS NEAR TO A FEW DEGREES BELOW NORMAL WITH MOSTLY CLEAR
SKIES. THE BIGGER ISSUE WILL BE GUSTY AFTERNOON WINDS AS THE AREA
REMAINS IN STRONG GRADIENT BETWEEN THE COOLER PAC NW TROUGH AND THE
MUCH WARMER SW RIDGE. THE MODELS DIVERGE FOR THURSDAY AND FRIDAY
WITH THE EC DROPPING ANOTHER ANOMALOUSLY COLD LOW DOWN THE PAC NW
COAST BRINGING COOLER CONDITIONS AND CONTINUED GUSTY AFTERNOON AND
EVENING BREEZES. THE GFS ALLOWS THE SW US RIDGE TO EXPAND INTO
NEVADA WITH WEAK ZONAL FLOW OVER THE PAC NW AND MUCH HIGHER HEIGHTS.
THE GFS ENSEMBLES ARE CONSISTENT BESIDES A FEW SLIGHTLY COOLER
SOLUTIONS. DID LOWER THE GOING FORECAST A FEW DEGREES AS THE 12Z GFS
IS COOLER THEN WHAT WE WERE ADVERTISING AND MIGHT STILL BE COOL
ENOUGH. GOING FORECAST WILL NEED TO BE COOLED SEVERAL DEGREES MORE
IF THE GFS STARTS LEANING TOWARD THE EC SOLUTION. MILNE
&&

.AVIATION...
A FEW SHOWERS OR STORMS POSSIBLE WITH THE LOW OVERHEAD EARLY THIS
EVENING OVER THE SIERRA INTO WESTERN NV BUT ANY CONVECTION SHOULD
KICK EAST AS WESTERLY FLOW DOMINATES IN THE EVENING. SOME AFTERNOON
GUSTS TO 25 MPH THE NEXT FEW DAYS...BUT OVERALL NO SIGNIFICANT
IMPACTS TO AVIATION OTHER THEN ISOLATED SHOWERS/STORMS. MUCH DRIER
AIR MOVES IN TONIGHT SO FOG AT TRK IS LESS LIKELY BUT A 10-20%
CHANCE OF OCCURRING.  MILNE

&&

.FIRE WEATHER...
ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP OVER THE AREA LATE
THIS AFTERNOON AND CONTINUE INTO THE EVENING. STORM MOTIONS OVER THE
ERN HALF OF THE FORECAST AREA SHOULD BE FAIRLY QUICK...LIMITING THE
CHANCE FOR WETTING RAINS. OVER THE NRN PORTIONS OF THE FORECAST AREA
STORM MOTIONS WILL BE SLOWER AND THUS SOME WETTING RAINS ARE
POSSIBLE...BUT THERE COULD STILL BE DRY LIGHTNING OUTSIDE THE CORES
OF STORMS.

INTO THE WEEKEND DRY CONDITIONS WILL RETURN WITH BREEZY WINDS
EXPECTED EACH DAY...ALTHOUGH THE WINDS WILL BE STRONGER SUNDAY AND
MONDAY. THIS IS IN RESPONSE TO AN APPROACHING UPPER LVL TROF. DRY SW
FLOW ALOFT WILL MOVE INTO THE AREA LATE SATURDAY. AS THE PRESSURE
GRADIENT INCREASES BY SUNDAY EXPECT AFTERNOON WIND GUSTS UP TO AS
HIGH AS 30 MPH ALONG THE HIGHWAY 395 CORRIDOR AND POINTS EAST...
ESPECIALLY NORTH OF HIGHWAY 50. WINDS WILL BE MARGINAL FOR RED FLAG
CONDITIONS SUNDAY. ZONE 450 IS LIKELY TO SEE THE STRONGEST WIND
GUSTS...BUT RIGHT NOW FEEL GUSTS 30 MPH OR BETTER WILL NOT BE
WIDESPREAD ENOUGH TO WARRANT ISSUING A FIRE WEATHER WATCH.
SUBSEQUENT SHIFTS WILL REEVALUATE THIS.

BY MONDAY AFTERNOON AND EARLY MONDAY EVENING WIND GUSTS AT OR ABOVE
30 MPH SHOULD BE WIDESPREAD ENOUGH...ALONG WITH RELATIVE HUMIDITY
DROPPING TO THE SINGLE DIGITS...THAT CRITICAL FIRE WEATHER
CONDITIONS MAY DEVELOP EAST OF THE SIERRA INTO WRN NV AND NORTH INTO
FAR NE CA. WILL NOT ISSUE A WATCH YET FOR MONDAY BUT THERE IS A
STRONG POSSIBILITY ONE WILL BE ISSUED BY LATE SATURDAY AFTERNOON FOR
MONDAY. MLF
&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

HTTP://WEATHER.GOV/RENO

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RENO NV
243 PM PDT FRI JUL 15 2011

CAZ072-NVZ003-152215-
GREATER LAKE TAHOE AREA-GREATER RENO-CARSON CITY-MINDEN AREA-
243 PM PDT FRI JUL 15 2011

...STRONG THUNDERSTORM IN EASTERN ALPINE AND WESTERN DOUGLAS COUNTY...

AT 239 PM PDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A STRONG THUNDERSTORM NEAR TOPAZ LAKE...AND MOVING NORTH AT 10 MPH.

OCCASIONAL LIGHTNING...SMALL PEA SIZE HAIL...AND GUSTY WINDS
OF AROUND 30 TO 40 MPH... ARE EXPECTED WITH THIS STORM.

THIS STORM WILL AFFECT TRAVELERS ON HIGHWAY 395 BETWEEN HOLBROOK
JUNCTION AND GARDNERVILLE. DRIVERS SHOULD EXPECT STRONG GUSTY CROSS
WINDS. HEAVY RAINFALL MAY RESULT IN PONDING WATER AND DECREASED
VISIBILITY. SLOW DOWN WHEN ENCOUNTERING HEAVY RAIN AND TURN ON YOUR
HEADLIGHTS.

&&

LAT...LON 3889 11966 3888 11953 3868 11960 3869 11966
TIME...MOT...LOC 2140Z 198DEG 8KT 3873 11962

LINDAMAN