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053
FXUS65 KREV 242218
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
318 PM PDT FRI OCT 24 2014

.SYNOPSIS...
LOW PRESSURE OFF THE WEST COAST WILL MOVE INLAND ON SATURDAY,
BRINGING A PERIOD OF STRONG GUSTY WINDS ALONG WITH LIGHT RAIN AND
MOUNTAIN SNOW. COOLER CONDITIONS WITH A FEW LINGERING SHOWERS ARE
EXPECTED EARLY SUNDAY WITH MILDER AND DRIER CONDITIONS FOR NEXT
WEEK.

&&

.SHORT TERM...
RAISED POP FURTHER FOR NORTHEAST CALIFORNIA AND THE NORTHERN
SIERRA SATURDAY AFTERNOON, OTHERWISE LITTLE CHANGE TO THE SHORT
TERM FORECAST. LOW PRESSURE ABOUT 550 MILES WEST OF SAN FRANCISCO
WILL MOVE NORTHEAST INTO THE OREGON AND WASHINGTON COASTS SATURDAY
AFTERNOON. A COLD FRONT ASSOCIATED WITH THE LOW WILL PUSH INTO THE
NORTHERN SIERRA AND NORTHEAST CALIFORNIA TOMORROW MORNING AND
INCREASE THE THERMAL GRADIENT ACROSS THE SIERRA AND WESTERN GREAT
BASIN.

WINDS ARE ALREADY GUSTY THIS AFTERNOON DUE TO MIXING DOWN OF
STRONGER WINDS ALOFT BETWEEN THE UPPER LOW OFF THE CALIFORNIA
COAST AND AN UPPER RIDGE OVER THE SOUTHWEST STATES. HOWEVER, WINDS
WILL INCREASE FURTHER SATURDAY MORNING AS THE FRONT APPROACHES AND
INCREASES THE GRADIENT. WITH THIS SYSTEM BEING A GRADIENT DRIVEN-
EVENT WITH SOUTHERLY FLOW ALOFT, THE SIERRA FOOTHILLS WEST OF
HIGHWAY 395 DO NOT TYPICALLY HAVE STRONGER WINDS THAN THE LEESIDE
VALLEYS. IN FACT, FOR THE RENO-SPARKS AREA WINDS ALONG AND EAST
OF HIGHWAY 395 TEND TO BE THE STRONGEST, AT LEAST UNTIL FROPA WHEN
WINDS ALOFT SWITCH TO SOUTHWEST ALOFT (FAVORED FOR STRONGER FOOTHILL
WINDS).

ELSEWHERE ON SATURDAY, THE BASIN AND RANGE EAST OF RENO WAS ADDED
TO THE WIND ADVISORY AS THE GRADIENT-DRIVEN PATTERN FAVORS STRONG
WINDS FOR ALL AREAS NEAR AND AFTER FROPA VERSUS SOUTHWEST FLOW
ALOFT WHICH WOULD FAVOR DOWNSLOPE WINDS IN THE LEE OF THE SIERRA.
ONE AREA THAT MAY SEE AN ADDED BOOST TO WINDS MAY BE ALONG HIGHWAY
395 BETWEEN SUSANVILLE AND DOYLE AS THE SOUTHERLY FLOW IS MORE
PERPENDICULAR TO THE DIAMOND RANGE AND COULD ENHANCE THE CHANCE
FOR DOWNSLOPING IN THAT AREA.

PRECIPITATION-WISE, THE FRONT WILL BEGIN TO FALL APART AS IT MOVES
INTO THE NORTHERN SIERRA AND WESTERN NEVADA WITH THE UPPER FORCING
MOVING INTO THE PACIFIC NORTHWEST. FOR THE CREST NORTH OF HIGHWAY 50,
THE OROGRAPHIC FLOW AND RESIDUAL MOISTURE DEPTH SHOULD BE SUFFICIENT
TO BRING SOME PRECIPITATION. HOWEVER, WITH MOISTURE AND FORCING
WANING PRECIPITATION SHOULD DROP OFF QUICKLY EAST OF THE CREST.
SATURDAY NIGHT, THERE WILL BE ONE MORE SHOT OF PRECIPITATION AS
ANOTHER DISTURBANCE MOVES AROUND THE LARGER UPPER TROUGH OVER THE
NORTHWEST CONUS. HOWEVER, THIS WILL BE RESTRICTED MAINLY TO
NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA AS THE DISTURBANCE
IS A GLANCING BLOW WITH THE BEST INSTABILITY FOR SHOWERS NORTH OF
INTERSTATE 80.

SUNDAY MORNING WILL BRING A LOW CHANCE FOR SHOWERS GENERALLY NORTH
OF HIGHWAY 50 AS THE MAIN TROUGH AXIS SWINGS THROUGH, WITH DRIER
MORE STABLE AIR ALOFT MOVING IN FOR AND END TO ANY SHOWERS IN THE
MORNING (ALTHOUGH PARTLY CLOUDY SKIES WILL CONTINUE). IF SKIES
REMAIN CLEAR SUNDAY NIGHT (HIGH CLOUDS IN SOME MODELS), WE COULD
FINALLY SEE A WIDESPREAD FREEZE FOR MOST LOWER VALLEYS THAT HAVE
NOT ALREADY SEEN A FREEZE. SNYDER

.LONG TERM...MONDAY THROUGH FRIDAY...
NO MAJOR SHIFTS FROM THE PREVIOUS THINKING FOR THIS FORECAST.
UNCERTAINTY REMAINS HIGH AS DETERMINISTIC RUNS TRY TO RESOLVE MAJOR
FEATURES LATE NEXT WEEK. THERE ARE TWO SYSTEMS IN QUESTION; THE
FIRST SKIRTING OUR NORTHERN ZONES MIDWEEK AND THE SECOND APPROACHING
AT THE END OF THE FORECAST PERIOD INTO NEXT WEEKEND.

WITH THE FIRST SYSTEM, WARM ADVECTION PRECIPITATION SHOULD REMAIN
NORTH OF INTERSTATE 80 AS THE PRIMARY MOISTURE PLUME IS DIRECTED
NORTHWARD IN THE CASCADES. STILL, WE COULD SEE A FEW SHOWERS DEVELOP
AS FAR SOUTH AS TRUCKEE IN THE SIERRA. MODELS CONTINUE TO HAVE
TROUBLE RESOLVING THE LATE WEEK SYSTEM AND HAVE CHANGED YET AGAIN.
THEY NOW SHOW A MORE HIGHLY AMPLIFIED RIDGE THAT WOULD SLOW DOWN AND
WEAKEN THE APPROACHING WAVE. HAVE BEGUN TO TRIM PRECIPITATION
CHANCES BACK TOWARD THE SIERRA CREST, BUT WILL NOT REMOVE COMPLETELY
UNTIL THE GFS AND ECMWF GAIN SOME STABILITY.

TEMPERATURES WILL BE DEPRESSED SLIGHTLY BELOW SEASONAL AVERAGES DUE
TO AMPLE CLOUD COVER EACH DAY. DID LOWER THE NORTHERN ZONES A DEGREE
OR TWO FOR WEDNESDAY SLOWING THE OVERALL WARMING TREND CLOSER TO THE
OREGON BORDER. OTHERWISE, HIGHS WILL REMAIN IN THE MID 60S FOR
WESTERN NEVADA VALLEY WARMING INTO THE UPPER 60S TO AROUND 70 BY THE
END OF THE WEEK. LOWS WILL CONTINUE TO BE WARMER THAN TYPICAL IN THE
LOW 40S IN WESTERN NEVADA AND AROUND FREEZING IN SIERRA VALLEYS.
BOYD

&&

.AVIATION...
WINDS WILL REMAIN BREEZY GENERALLY OUT OF THE SOUTH THROUGH THE
AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS. WIND GUSTS SHOULD BE
UP TO 30 KTS. TVL WILL LIKELY BE THE BREEZIEST AS SOUTHERLY FLOW
TENDS TO CHANNEL WINDS THROUGH LOCAL VALLEYS; GUSTS UP TO 40 KTS
ARE POSSIBLE. OTHERWISE, CONDITIONS WILL BE VFR THROUGH EARLY
SATURDAY MORNING.

SATURDAY, THE MAIN SYSTEM MOVES IN WITH INCREASING WINDS ALOFT.
WINDS WILL BE LOCALLY BREEZY AFTER 06Z TONIGHT WITH SOME MTN WAVE
TURBULENCE. AFTER 12Z SAT, THE WINDS INCREASE WITH TURBULENCE AND
LLWS LIKELY WHERE WINDS ARE CHANNELED BY STRONG WINDS ALOFT. IN
GENERAL, EXPECT SW WINDS OF 25-30 KT AT THE TERMINALS WITH GUSTS
40-45 KTS AFT 15Z POSSIBLY LASTING THROUGH 00Z SUN. SIERRA FRONT
TERMINALS, KRNO AND KCXP, MAY SEE BRIEF BUT HIGHER WINDS SUSTAINED
AROUND 35 KTS WITH GUSTS UP TO 50 KTS.

AS THE COLD FRONT NEARS, EXPECT SOME MVFR/IFR CONDITIONS IN -RA WITH
MTN OBSCN. THIS WILL BEGIN OVER WESTERN LASSEN DOWN THROUGH THE
TAHOE BASIN BY 18Z AND SLOWLY SHIFT EASTWARD TO THE SIERRA FRONT BY
00Z. THE BIGGEST THREAT WILL REMAIN IN THE SIERRA. WALLMANN/BOYD

&&

.FIRE WEATHER...
GUSTY WINDS WILL CONTINUE THROUGH THIS EVENING WITH GUSTS PEAKING
OUT AROUND 30-35 MPH. LOW PRESSURE MOVES INTO NORTHERN CALIFORNIA
TONIGHT WITH INCREASING WINDS ACROSS THE SIERRA AND WESTERN
NEVADA. THE INCREASED WINDS OVERNIGHT WILL KEEP THE LOWER LEVELS
MIXED, WITH MODERATE TO POOR OVERNIGHT RECOVERY TONIGHT. WINDS
WILL ONLY CONTINUE TO INCREASE AFTER THE SUN COMES UP SATURDAY
MORNING AS THE GRADIENTS TIGHTEN UP IN RESPONSE TO THE INCOMING
FRONT.

RED FLAG WARNINGS HAVE BEEN ISSUED FOR WESTERN NEVADA ON SATURDAY,
AS STRONG WIND GUSTS UP TO 55 MPH OR MORE WILL COMBINE WITH
MODERATELY DRY CONDITIONS. WITH THE COOLER TEMPERATURES THE HUMIDITY
WON`T GET DOWN INTO THE SINGLE DIGITS, ALTHOUGH WITH STRONG WINDS OF
THIS MAGNITUDE THE CRITICAL CONDITIONS WILL STILL BE THERE. THE
STRONGEST WINDS WILL BE BETWEEN 1100-1700 SATURDAY, AND ESPECIALLY
ALONG THE HIGHWAY 395 CORRIDOR. THE FRONT WILL MOVE THROUGH THE
RENO-CARSON CITY-MINDEN AREAS AROUND 1400-1600 SATURDAY, WITH THE
MOST CRITICAL TIMING AROUND MID DAY. THE COLD FRONTAL PASSAGE IN THE
AFTERNOON WILL HELP INCREASE HUMIDITY AND DAMPEN THE WINDS A BIT
ALONG THE SIERRA FRONT, WHILE CRITICAL CONDITIONS EAST OF RENO WILL
LIKELY CONTINUE THROUGH AROUND 2000. HOON

&&


.REV WATCHES/WARNINGS/ADVISORIES...
NV...WIND ADVISORY FROM 8 AM TO 11 PM PDT SATURDAY NVZ003-005.

     LAKE WIND ADVISORY FROM 11 PM THIS EVENING TO 11 PM PDT SATURDAY
     FOR LAKE TAHOE IN NVZ002.

     RED FLAG WARNING FROM 8 AM TO 8 PM PDT SATURDAY NVZ453-459.

     WIND ADVISORY FROM 11 AM TO 11 PM PDT SATURDAY NVZ001-004.

     RED FLAG WARNING FROM 8 AM TO 3 PM PDT SATURDAY NVZ450.

CA...WIND ADVISORY FROM 8 AM TO 11 PM PDT SATURDAY CAZ070-071.

     WIND ADVISORY FROM 11 AM TO 11 PM PDT SATURDAY CAZ073.

     LAKE WIND ADVISORY FROM 11 PM THIS EVENING TO 11 PM PDT SATURDAY
     FOR LAKE TAHOE IN CAZ072.

&&

$$

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











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