Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 221006
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
306 AM PDT WED OCT 22 2014

.SYNOPSIS...
AFTERNOON TEMPERATURES WILL WARM THE REST OF THE WEEK. MOISTURE
AHEAD OF A LOW PRESSURE SYSTEM IN THE PACIFIC WILL PRODUCE RAIN
OVER NORTHEAST CALIFORNIA AND NORTHWEST NEVADA THURSDAY. THE LOW
WILL MOVE INLAND ON FRIDAY NIGHT AND SATURDAY BRINGING A PERIOD OF
GUSTY WINDS AND THE POTENTIAL FOR RAIN AND MOUNTAIN SNOW.

&&

.SHORT TERM...

EXPECT A SEASONABLY WARM AFTERNOON TODAY ACROSS THE SIERRA AND
WESTERN NEVADA WITH INCREASING HIGH CLOUDS THIS AFTERNOON. AS A
PACIFIC TROUGH ARRIVES ALONG THE WEST COAST TONIGHT, SIERRA
RIDGE WINDS WILL BECOME STRONGER, WITH GUSTS ACROSS RIDGETOPS
INCREASING TO 30-50 MPH.

FORECAST CONFIDENCE HAS INCREASED TO MEDIUM FOR THE PACIFIC TROUGH
TO SPREAD PRECIPITATION ACROSS PLUMAS, LASSEN, MODOC AND NORTHERN
WASHOE COUNTIES THURSDAY AND THURSDAY NIGHT. PRECIPITABLE WATER
VALUES WILL BE HIGH, LIKELY IN THE 0.75 TO 0.85 INCH RANGE, BUT
FORCING FOR LIFT FAIRLY WEAK AS HIGH PRESSURE SLOWLY BUILDS OVER
THE AREA. THE FORECAST IS ON TRACK FOR RAINFALL TOTALS 0.25 TO
0.50 INCHES DUE TO UPSLOPE LIFT WEST OF A LINE FROM SUSANVILLE TO
PORTOLA, DECREASING TO 0.10 TO 0.20 FOR THE SURPRISE VALLEY AND
NORTHERN WASHOE COUNTY. THERE IS STILL A SLIGHT CHANCE A WEAK
IMPULSE COULD EJECT FROM THE PACIFIC LOW AND PROVIDE FORCING FOR
LIFT. IF THAT OCCURRED, THESE PRECIPITATION TOTALS COULD EASILY
DOUBLE DUE TO THE AMPLE MOISTURE AVAILABLE. SNOW LEVELS SHOULD BE
ABOVE 8000-9000 FEET THROUGH FRIDAY.

A LOW-PRESSURE TROUGH ALONG THE WEST COAST WILL CREATE BREEZY
SOUTH WINDS FRIDAY AFTERNOON. LATEST MODEL GUIDANCE TRENDED A BIT
SLOWER SUCH THAT THE STRONGER WINDS MAY NOT DEVELOP UNTIL AFTER
SUNSET. NONETHELESS, THERE IS POTENTIAL FOR GRADIENT-DRIVEN GUSTS
TO 30 MPH FRIDAY AFTERNOON, WHICH ALONG WITH LOW HUMIDITY COULD
CREATE FIRE CONCERNS ACROSS NEVADA ZONES FRIDAY AFTERNOON,
ESPECIALLY SOUTH OF HIGHWAY 50.

THE FORECAST REMAINS ON TRACK FOR SOUTH-SOUTHWEST WINDS TO
INCREASE FRIDAY NIGHT. THE STRONGEST WINDS ALOFT ARE EXPECTED
ACROSS NORTHWEST NV AND NORTHERN CA NEAR THE UPPER LEVEL JET MAX.
HOWEVER, THE STRONGEST PRESSURE GRADIENT MAY SET UP ACROSS
WESTERN NV, INCLUDING ACROSS THE WASHOE VALLEY AND THE I-80
CORRIDORS, AND ACROSS THE SOUTHERN SIERRA INCLUDING MONO COUNTY.
EXPECT WIND GUSTS FRIDAY NIGHT IN WESTERN NV VALLEYS UP TO 45 MPH
(IN WIND PRONE AREAS 50-60 MPH), AND ACROSS RIDGETOPS 60-80 MPH.
THESE WINDS ARE LIKELY TO IMPACT TRAVELERS, ESPECIALLY HIGH
PROFILE VEHICLES AND AVIATION EAST OF THE SIERRA FRIDAY NIGHT. JCM

LONG TERM...SATURDAY THROUGH TUESDAY...

MODELS ARE STICKING WITH A MORE PROGRESSIVE TROUGH EARLY IN THE
PERIOD WITH THE COLD FRONT REACHING NORTHEAST CA BY SAT MORNING
AND THEN CROSSING THE SIERRA AND WESTERN NV DURING THE DAYTIME.
THERE CONTINUES TO BE SOME SLIGHT TIMING DIFFERENCES BUT OVERALL
THE MODEL SPREAD HAS DECREASED AND ALLOWED US TO GO AHEAD AND
RAISE POPS TO LIKELY FOR THE TAHOE BASIN NORTHWARD ACROSS
NORTHEAST CA SATURDAY. LOWER CHANCE POPS WERE MAINTAINED FURTHER
EAST AND SOUTH AS MAIN MOISTURE PUSH STAYS ACROSS NORTHERN CA
BEFORE WANING SAT AFTERNOON AND EVENING. MOISTURE ASSOCIATED WITH
THIS TROUGH IS A BIT BETTER THAN PREVIOUS TROUGHS. SO EVEN THOUGH
IT APPEARS THE SYSTEM WILL BE PROGRESSIVE, PRECIP AMOUNTS WILL BE
A LITTLE BETTER, POSSIBLY APPROACHING 0.50 INCHES FROM WESTERN
LASSEN COUNTY SOUTHWARD TO PLUMAS AND SIERRA COUNTIES. WE
MAINTAINED A LOW CHANCE OF SHOWERS FOR SAT NIGHT-SUN AS THE GFS
SHOWS A WEAK SHORTWAVE FEATURE TRACKING ALONG THE OREGON BORDER
ON BACK SIDE OF TROUGH WHERE SUFFICIENT MOISTURE WILL LINGER.

OTHERWISE, EXPECT BREEZY AND COOLER CONDITIONS SATURDAY WITH SOME
LOCALLY STRONG WINDS NEAR THE HIGHWAY 395 CORRIDOR DURING THE
MORNING AS THE COLD FRONT APPROACHES. LIGHTER WINDS AND COOL
CONDITIONS WILL PREVAIL SUNDAY BEFORE A SLIGHT WARMUP OCCURS MON-TUE
UNDER WEAK RIDGE/ZONAL FLOW. PERIODS OF MID AND HIGH CLOUDS MAY SLOW
WARMING MONDAY. MODELS ARE BEGINNING TO SHOW SOME POTENTIAL FOR A
SYSTEM AROUND THE MIDDLE OF NEXT WEEK WITH RAIN POSSIBLY REACHING
THE AREA BY LATE TUESDAY. HOWEVER, CONFIDENCE IS LOW RIGHT NOW.
HOHMANN

&&

.AVIATION...
VFR CONDITIONS AND LIGHT WINDS TODAY WITH AREAS OF HIGH CLOUDS
OVERHEAD. INCREASING PACIFIC MOISTURE WILL BRING A BAND OF RAIN
MAINLY NORTH OF SUSANVILLE-GERLACH LINE BY THURSDAY, WITH LIGHTER
RAIN SHOWERS POSSIBLY SPREADING SOUTHWARD TO NEAR INTERSTATE 80.
WINDS WILL ALSO INCREASE TONIGHT INTO THURSDAY OVER RIDGES WITH
GUSTS AROUND 40KT. MJD/WH


&&

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

$$

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






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