Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 040406
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
906 PM PDT THU SEP 3 2015

.UPDATE...

NO REAL CHANGES TO MAKE TO THE CURRENT FORECAST. WINDS ARE
STARTING TO DECREASE SO WE WILL CLEAN UP THAT WORDING FOR THE REST
OF THE EVENING. LINGERING CLOUDS MAY KEEP TEMPS FOR FALLING VERY
QUICKLY THIS EVENING...BUT OVERNIGHT LOWS STILL LOOK REASONABLE.
LATEST MODEL GUIDANCE IS STILL ON TRACK FOR STRONGER WINDS
FRIDAY...SO THAT FORECAST LOOKS REASONABLE AS WELL. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 304 PM PDT THU SEP 3 2015/

SYNOPSIS...

GUSTY WINDS FRIDAY AFTERNOON AND EVENING WILL RESULT IN HAZARDOUS
BOATING CONDITIONS, AREAS OF BLOWING DUST, AND PERIODS OF CRITICAL
FIRE WEATHER CONDITIONS. A COLD FRONT PASSAGE FRIDAY WILL ALSO BRING
WELL BELOW NORMAL TEMPERATURES TO START THE HOLIDAY WEEKEND.

SHORT TERM...
A COLD AIR MASS AND CLOSED LOW PRESSURE SYSTEM WILL MOVE FROM THE
PACIFIC NORTHWEST SOUTHWARD INTO NV/CA TONIGHT AND FRIDAY. THE
UPPER-LEVEL SYSTEM WILL THEN MOVE EASTWARD TOWARDS UTAH FRIDAY
NIGHT THROUGH SATURDAY NIGHT.

A COLD FRONT PASSAGE WILL RESULT IN INCREASING WINDS FRIDAY
AFTERNOON WITH GUSTS 30 TO 40 MPH. IMPACTS FRIDAY INCLUDE
HAZARDOUS CONDITIONS ON AREA LAKES, DANGEROUS CROSSWINDS FOR HIGH
PROFILE VEHICLES AND BLOWING DUST ACROSS THE WESTERN NV DESERTS.
TEMPERATURES IN COLDER SIERRA VALLEYS WILL COOL TO THE MID TO
UPPER 20S FRIDAY NIGHT AND IN WESTERN NV VALLEYS TO THE MID 30S.
SATURDAY NIGHT IS EXPECTED TO BE EVEN COLDER WITH LOW TEMPERATURES
UP TO 5 DEGREES COOLER. GARDENERS AND ANYONE WITH PLANS TO BE
OUTDOOR IN THE DESERT OR IN SIERRA VALLEYS THIS WEEKEND SHOULD
BE PREPARED FOR OVERNIGHT FREEZING TEMPERATURES.

THIS SYSTEM WILL BRING A VERY DRY AIR MASS ACROSS THE EASTERN
SIERRA AND WESTERN NV WHICH, ALONG WITH GUSTY WINDS, WILL CREATE
DANGEROUS FIRE WEATHER CONDITIONS FRIDAY AFTERNOON AND EVENING FOR
SOME AREAS. SEE THE FIRE WEATHER DISCUSSION BELOW FOR DETAILS.

REGARDING PRECIPITATION CHANCES: A SHORTWAVE STRENGTHENS OVER FAR
NORTHWEST NV FRIDAY PROVIDING JET DYNAMICS AND MODERATE FORCING
FOR LIFT. AS THE COLDEST AIR ALOFT MOVES ACROSS NORTHERN NV
FRIDAY NIGHT THROUGH SATURDAY NIGHT, THIS WILL INCREASE
INSTABILITY SOMEWHAT (ALTHOUGH UPPER-LEVEL LAPSE RATES LOOK
STABLE). HOWEVER, A LACK OF DEEP MOISTURE IS THE LIMITING FACTOR.
THE UPSHOT IS THERE ARE CHANCES FOR SHOWERS FRIDAY AFTERNOON
THROUGH SATURDAY EVENING FOR LOCATIONS NORTH OF A PORTOLA-PYRAMID
LAKE-LOVELOCK LINE (INCLUDING BLACK ROCK CITY). INSTABILITY
IS LIMITED SO ANY THUNDERSTORMS WON`T BE STRONG, BUT WE CAN`T RULE
OUT ISOLATED THUNDER/LIGHTNING FRIDAY AFTERNOON, ESPECIALLY
CLOSER TO THE OREGON BORDER. JCM

LONG TERM...SUNDAY THROUGH THURSDAY...

MAIN CHANGES TO THE FORECAST WERE TO RAISE HIGH TEMPERATURES NEXT
WEEK AS MODELS ARE WEAKER WITH THE SHORTWAVE MOVING THROUGH THE
EXITING TROUGH.

BY SUNDAY, THE EXITING TROUGH AXIS WILL BE OVER THE ROCKY MOUNTAIN
STATES AS RIDGING SLOWLY BUILDS OVER THE EASTERN PACIFIC. ALONG THE
WEST COAST THE JET STREAM WILL REMAIN NORTH OF U.S./CANADIAN BORDER
THROUGH MOST OF NEXT WEEK WITH THE EAST PACIFIC RIDGE VERY SLOWLY
BUILDING INTO THE WEST COAST.

THIS WILL BRING DRY CONDITIONS TO THE REGION WITH LIGHT WINDS AND
WARMING TEMPERATURES THROUGHOUT THE WEEK. HIGH TEMPS ON SUNDAY WILL
REMAIN A FEW DEGREES BELOW NORMAL. BY MIDWEEK, HIGH TEMPS WILL
REBOUND TO ABOUT 6-8 DEGREES ABOVE NORMAL. LOW TEMPS WILL BE SLOWER
TO REBOUND IN THE VERY DRY AIRMASS WITH MANY SIERRA VALLEYS
REMAINING NEAR OR BELOW FREEZING THROUGH MIDWEEK. TOLBY

AVIATION...

TROUGH MOVING THROUGH THE PNW WILL CONTINUE TO BRING GUSTY WEST
WINDS THROUGH FRIDAY. GUSTS 20-25 KTS WILL SUBSIDE TODAY BETWEEN 04-
06Z WITH STRONGER GUSTS 25-30 KTS ON FRIDAY. WINDS ON FRIDAY COULD
BEGIN TO PICK UP MUCH EARLIER THAN USUAL, STARTING AS EARLY AS
15Z AT SIERRA TERMINALS AND AS EARLY AS 17Z FOR WESTERN NEVADA.
GUSTS TO 50 KTS WILL CONTINUE ALONG THE SIERRA CREST THROUGH
FRIDAY WITH LEE SIDE TURBULENCE LIKELY.

VFR CONDITIONS EXPECTED AT ALL TERMINALS WITH MODERATE AFTERNOON
CONVECTIVE BUILDUPS ALONG AND EAST OF THE SIERRA FROM KTVL NORTH
WILL CONTINUE THROUGH 04Z WITH CLOUD BASES 060 AGL IN THE SIERRA
AND 080 AGL IN WESTERN NEVADA. VERY SLIGHT CHANCE (10 PERCENT) OF
WEAK THUNDERSTORMS REMAINS NEAR THE OREGON BORDER NORTH OF
SUSANVILLE/GERLACH THROUGH THIS AFTERNOON. TOLBY

FIRE WEATHER...

GUSTS ARE IN THE 25-30 MPH (LOCALLY 30-35) RANGE THIS AFTERNOON AS A
COLD FRONT REMAINS HUNG UP OVER FAR NORTHERN CALIFORNIA AND NEVADA.
AS TEMPERATURES HAVE COOLED SOME 4-8 DEGREES OVER YESTERDAY AND
DEWPOINTS HAVE RISEN, HUMIDITIES ARE ABOVE TO WELL ABOVE CRITICAL
THRESHOLDS (AT LEAST WHERE THERE IS WIND). TONIGHT WILL SEE MODERATE
TO GOOD RECOVERIES EVERYWHERE WITH COOLER (CONSIDERABLY IN SOME
AREAS) TEMPERATURES AS COMPARED TO LAST NIGHT.

FRIDAY, MODELS CONTINUE TO INDICATE A PRONOUNCED DRY SLOT PUSHING
INTO AREAS SOUTH OF I-80 ABOVE ABOUT 650-700 MB (10,000-11,000 FT
MSL). BASED ON EXPECTED TEMPERATURES BY EARLY-MID AFTERNOON, THE
DRIER AIR ALOFT SHOULD BEGIN TO BE TAPPED AND MOS GUIDANCE INDICATES
FALLING DEWPOINTS DURING THE AFTERNOON AND EARLY EVENING. THEREFORE,
CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED FOR LOWER ELEVATIONS
SOUTH OF I-80 WITH THE MOST PROLONGED CONDITIONS EAST OF HIGHWAY 395
OUT INTO THE BASIN AND RANGE. IF LESS DRY AIR IS TAPPED THAN
EXPECTED, AREAS ALONG/WEST OF HIGHWAY 395 IN THE SIERRA FRONT MAY
SEE A SHORTER PERIOD OF CRITICAL CONDITIONS AS THE INCOMING TROUGH
COOLS TEMPERATURES BY EARLY EVENING.

FRIDAY NIGHT AND SATURDAY, THE COLD FRONT MOVES THROUGH AND BRINGS
WELL BELOW AVERAGE TEMPERATURES TO THE REGION WITH A SUBSTANTIAL
REDUCTION IN WINDS. TEMPERATURES RETURN TO NEAR AVERAGE EARLY NEXT
WEEK WITH LIGHT WINDS EXPECTED. SNYDER

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 11 AM TO 9 PM PDT FRIDAY NVZ002.

     BLOWING DUST ADVISORY FROM 2 PM TO 9 PM PDT FRIDAY NVZ004-005.

     RED FLAG WARNING FROM 2 PM TO 9 PM PDT FRIDAY NVZ453-459.

     RED FLAG WARNING FROM 2 PM TO 9 PM PDT FRIDAY NVZ450.

     LAKE WIND ADVISORY FROM 2 PM TO 9 PM PDT FRIDAY FOR PYRAMID LAKE
     IN NVZ001-004.

CA...LAKE WIND ADVISORY FROM 11 AM TO 9 PM PDT FRIDAY CAZ071>073.

     RED FLAG WARNING FROM 2 PM TO 9 PM PDT FRIDAY CAZ273.

&&

$$

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


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