Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 272159
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
259 PM PDT THU AUG 27 2015

.SYNOPSIS...

TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH FRIDAY WITH ONLY A
SLIGHT CHANCE FOR A SHOWER OR THUNDERSTORM SOUTH OF HIGHWAY
50 TODAY. LOW PRESSURE WILL MOVE INTO THE WEST COAST THIS WEEKEND
AND BRING BREEZY TO WINDY CONDITIONS AND COOLER TEMPERATURES.

&&

.SHORT TERM...

THE SHORT TERM FORECAST IS IN FOR A TRANSITION AS A VIGOROUS...
FALL-LIKE...TROUGH MAKES ITS WAY INTO THE PACIFIC NORTHWEST
STARTING FRIDAY AND BEGINS TO AFFECT OUR REGION BY EARLY SATURDAY.

THIS TROUGH WILL HOLD OFF LONG ENOUGH FOR ONE MORE DAY OF ABOVE
AVERAGE TEMPERATURES FRIDAY WITH RELATIVELY DRY CONDITIONS. BUT
BEFORE THAT THERE COULD BE A FEW ISOLATED STORMS SOUTH OF HIGHWAY
50 AND WEST OF HIGHWAY 95 LATE THIS AFTERNOON AND THIS EVENING.
THIS IS IN RESPONSE TO DAYTIME HEATING IN THE FAVORABLE
MONO/MINERAL CONVERGENCE AREA. ANY STORMS THAT DEVELOP MAY
TRANSLATE NORTH AS WESTERLY WINDS DEVELOP LATE IN THE DAY AND
BEGIN TO FOCUS LIFT AND INSTABILITY ON THE SOUTHERN PINE NUT
MOUNTAINS. GIVEN THE DRY LOW LEVELS LITTLE PCPN SHOULD REACH THE
GROUND.

AS THE TROUGH APPROACHES FRIDAY...CLOUDS SHOULD BEGIN TO INCREASE
ACROSS THE NORTHERN FORECAST AREA...BUT LOW LEVEL LIFT AND
MOISTURE IS INSUFFICIENT FOR PCPN. THIS WILL BEGIN TO CHANGE BY
EARLY SATURDAY MORNING AS INCREASING LOW LEVEL MOISTURE COMBINES
WITH AN APPROACHING SURFACE FRONT TO PRODUCE SHOWERS MAINLY ALONG
AND NORTH OF A LINE FROM PORTOLA TO GERLACH BY SATURDAY AFTERNOON.
TO GO ALONG WITH THIS POTENTIAL FOR SHOWERS...LOW TO MID LEVEL
FLOW BEGINS TO INCREASE WITH AN APPROACHING UPPER LEVEL JET. THESE
WINDS EXTEND SOUTH THROUGH THE TAHOE BASIN AND INTO WESTERN NEVADA
BY MIDDAY SATURDAY. GRADIENT WINDS WILL INCREASE IN RESPONSE TO
THE INCREASED WINDS ALOFT AND A NOTABLE LOW LEVEL THERMAL GRADIENT
ASSOCIATED WITH A COLD FRONT. GUSTS 35-45 MPH ARE LIKELY WEST OF
HIGHWAY 95 WITH LOCAL GUSTS UP TO 50 MPH POSSIBLE IN WIND PRONE
AREAS. WE COULD REACH CRITICAL CONDITIONS SOUTH OF INTERSTATE 80
AS RH VALUES WILL ALSO BE FAIRLY LOW...BUT NOT IN THE SINGLE
DIGITS...SATURDAY. THIS WILL BE COVERED MORE IN THE FIRE WEATHER
SECTIONS BELOW. FOR AREA LAKES THE GUSTY WINDS WILL BE MORE
WIDESPREAD STARTING LATER FRIDAY NIGHT. EVEN THOUGH NORTHEAST
CALIFORNIA MAY SEE A FEW GUSTS OVER 30 MPH FRIDAY AFTERNOON...WE
WILL HOLD OFF ISSUING LAKE WIND ADVISORIES AT THIS TIME. BOATERS
SHOULD BE AWARE THAT THE WINDS COULD BE STRONGER FOR LATE FRIDAY
AFTERNOON ON EAGLE...FRENCHMAN AND DAVIS LAKES. ALL AREAS WITH
LAKES WILL LIKELY NEED ADVISORIES BY EARLY SATURDAY.

SOUTH OF INTERSTATE 80 CONDITIONS SHOULD REMAIN LARGELY PCPN FREE
THROUGH SATURDAY NIGHT AS THE BEST MOISTURE AND LIFT REMAIN OVER
THE FAR NORTH. TEMPERATURES WILL BE IN FOR A DIVE AS HIGHS ON
SATURDAY COULD BE 10-14 DEGREES LOWER THAN FRIDAY. BY LATE
SATURDAY NIGHT LOW TEMPERATURES COULD DROP SLIGHTLY BELOW AVERAGE
IN NORTHEAST CALIFORNIA...BUT CONTINUED BREEZY CONDITIONS OVERNIGHT
SATURDAY WILL HOLD LOWS TO NEAR AVERAGE FOR WESTERN NEVADA. 20

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

BY SUNDAY THE COLD FRONT WILL BE WELL EAST OF THE AREA WITH HIGH
TEMPERATURES REMAINING A FEW DEGREES BELOW NORMAL. TEMPERATURES WILL
WARM BACK UP TO NEAR NORMAL FOR THE BEGINNING OF THE WEEK WITH A
RETURN TO TYPICAL AFTERNOON ZEPHYR WINDS.

ANOTHER STRONG TROUGH (FOR THIS TIME OF YEAR) IS PROJECTED TO BRUSH
THE AREA AGAIN LATER IN THE WEEK. THIS WILL PUSH TEMPERATURES BACK
BELOW NORMAL AND COULD AGAIN BRING A DAY OR TWO OF STRONGER WINDS.
HUMIDITIES LOOK TO REMAIN A LITTLE LOWER WITH THE NEXT TROUGH, WHICH
COULD AGAIN INCREASE FIRE WEATHER CONCERNS. TOLBY

&&

.AVIATION...

A FEW LOW TOP THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON IN WESTERN
NEVADA. STORMS ARE SHORT-LIVED AND EXPECTED TO SUBSIDE BY 02Z. WEST
WINDS TODAY GUSTING TO 25KTS UNTIL 04Z. STRONG FALL-LIKE TROUGH
EXPECTED TO BRING STRONG WINDS GUSTING UP TO 35KTS FRIDAY EVENING
INTO SATURDAY WITH RIDGE GUSTS UP TO 65KTS POSSIBLE. TOLBY

&&

.FIRE WEATHER...

WINDS WILL START TO INCREASE FRIDAY AFTERNOON WITH GUSTS 30-35
MPH, WITH MINIMUM HUMIDITY AROUND 15%. SOME LOCATIONS IN
NORTHWEST NV AND THE SIERRA FRONT MAY BRIEFLY MEET CRITICAL FIRE
WEATHER CONDITIONS, ALTHOUGH THE HUMIDITY WILL LIKELY EDGE UP
ABOVE 15% AFTER THE WINDS INCREASE. FARTHER EAST ACROSS WEST
CENTRAL NV, HUMIDITY IS LIKELY TO DROP TO AROUND 10 PERCENT, BUT
WIND GUSTS WILL ALSO BE LOWER, MAINLY BETWEEN 25-30 MPH.

THE MORE SIGNIFICANT WIND EVENT IS EXPECTED LATE FRIDAY NIGHT AND
SATURDAY AS STRONG 700 MB FLOW INCREASES TO NEAR TO 50 KT, WHICH
IS UNUSUALLY STRONG FOR LATE AUGUST. WIND GUSTS WILL RANGE FROM
35-45 MPH IN THE TAHOE BASIN OVERNIGHT THROUGH SATURDAY MORNING,
AND CONTINUE THROUGH SATURDAY AFTERNOON ACROSS MOST LOWER
ELEVATIONS AS TIGHT SURFACE PRESSURE GRADIENT CONTINUES AFTER THE
MAIN TROUGH PASSAGE. SOME OF THE MODEL GUIDANCE WAS HINTING AT A
POSSIBLE SHORT PERIOD OF DOWNSLOPE WIND ENHANCEMENT SATURDAY
MORNING. ALTHOUGH WE ARE NOT EXPECTING DAMAGING WINDS, THERE COULD
BE LOCAL GUSTS TO 50 MPH IN SOME WIND PRONE AREAS. AFTER THREE
WEEKS WITHOUT PRECIPITATION, FUEL MOISTURES HAVE DRIED OUT TO NEAR
AVERAGE FOR THIS TIME OF YEAR. SO EVEN THOUGH HUMIDITY MAY NOT BE
EXCEEDINGLY LOW, THE MAGNITUDE OF THE WINDS ALONE COULD CREATE
POTENTIALLY CRITICAL FIRE WEATHER CONDITIONS NEAR THE SIERRA, AND
EXTENDING INTO WESTERN NV MAINLY BETWEEN I-80 AND HIGHWAY 50.
THEREFORE WE WILL ISSUE A FIRE WEATHER WATCH FOR THESE AREAS.

FARTHER NORTH INTO NORTHEAST CA-NORTHWEST NV, GUSTY WINDS ARE
ALSO EXPECTED BUT HUMIDITY WILL INCREASE MORE QUICKLY. THICKER
CLOUD COVER WITH SHOWERS MAY LIMIT THE AMOUNT OF MIXING WHEN THE
STRONGER 700 MB FLOW MOVES OVERHEAD, SO WE WILL JUST KEEP A WIND
HEADLINE FOR THESE AREAS BUT NOT INCLUDE THEM IN THE WATCH. MJD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...FIRE WEATHER WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
     AFTERNOON NVZ450-453.

CA...FIRE WEATHER WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
     AFTERNOON CAZ273.

     FIRE WEATHER WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
     MORNING CAZ272.

&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)


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