Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 012242
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
242 PM PST SUN FEB 1 2015

.SYNOPSIS...

HIGH PRESSURE OVER THE SIERRA NEVADA TODAY WILL WEAKEN MONDAY AND
TUESDAY AS WEAK SYSTEMS MOVE INTO OREGON AND WASHINGTON. SOME
SHOWERS ARE POSSIBLE NEAR THE OREGON BORDER BOTH DAYS WITH MOSTLY
CLOUDY SKIES AND MILD TEMPERATURES ELSEWHERE. HIGH PRESSURE WILL
STRENGTHEN AGAIN FOR MIDWEEK WITH CONTINUED MILD TEMPERATURES AND
DRY CONDITIONS. A WARM PACIFIC STORM MAY AFFECT NORTHERN CALIFORNIA
AND NEVADA NEXT WEEKEND.

&&

.SHORT TERM...

A STREAM OF PACIFIC MOISTURE IS PUSHING INTO THE PACIFIC
NORTHWEST TODAY, WEAKENING THE RIDGE AND SPREADING HIGH CLOUDS
ACROSS THE SIERRA AND NORTHWEST NEVADA. RADAR MOSAICS ARE SHOWING
PRECIPITATION DEVELOPING ACROSS OREGON AND INTO IDAHO ASSOCIATED
WITH A SHORTWAVE MOVING THROUGH THE FLOW. THIS WILL RIDE ALONG
THE NORTHERN CA/NV BORDER WITH JUST SLIGHT CHANCES FOR SHOWERS IN
NORTHERN LASSEN AND EXTREME NORTHERN WASHOE COUNTIES ALONG WITH
THE SURPRISE VALLEY TONIGHT. A SECOND SHORTWAVE MOVES ACROSS
NORTHERN CA/NV MONDAY FOLLOWED BY ANOTHER ONE TUESDAY. THESE DO
BRING DEEPER MOISTURE AND CHANCES FOR SHOWERS NORTH OF A PORTOLA-
LOVELOCK LINE MONDAY AND TUESDAY. HOWEVER, WITH LITTLE IN THE WAY
OF DYNAMICS, AM NOT EXPECTING SIGNIFICANT AMOUNTS OF
PRECIPITATION. SNOW LEVELS WILL BE MAINLY IN THE 7000-8000 FOOT
RANGE WITH LITTLE IF ANY IMPACTS ON ROADWAYS. AREAS SOUTH OF
THERE WILL REMAIN DRY WITH PERIODS OF CLOUDINESS.

EACH WAVE WILL BRING AN INCREASE IN 700 MB WINDS TO AROUND 30-40
MPH ACROSS NORTHERN CA/NV MONDAY AND THEN AGAIN TUESDAY/TUESDAY
NIGHT. THERE IS NOT MUCH OF A SURFACE GRADIENT, BUT SOME WIND MAY
BE ABLE TO MIX DOWN FOR BREEZY CONDITIONS IN THE SURPRISE VALLEY
AND THE BLACK ROCK DESERT. SIERRA RIDGE WINDS WILL ALSO BE GUSTY,
UP TO 65 MPH.

DESPITE THE CLOUDS, MILD TEMPERATURES ARE EXPECTED WITH HIGHS
MAINLY IN THE 60S IN VALLEYS WITH UPPER 40S TO MID 50S IN THE
SIERRA. OVERNIGHT LOWS WILL BE WELL ABOVE NORMAL DUE TO MOISTURE
AND CLOUDS WITH MID 30S TO LOW 40S IN WESTERN NEVADA AND UPPER 20S
TO MID 30S IN THE SIERRA. DJ

.LONG TERM...

ONLY A FEW CHANGES TO THE LONG TERM TODAY. DID LOWER SNOW LEVELS A
BIT FOR FRIDAY NIGHT AND SLIGHTLY INCREASED POPS FARTHER SOUTH
ALONG THE SIERRA CREST OF MONO COUNTY FOR THAT TIME PERIOD. ALSO
CONTINUED TO TREND UP WINDS FOR THURSDAY AND FRIDAY. THE BIGGEST
IMPACT IN WESTERN NEVADA MAY BE THE WINDS ON FRIDAY WHICH CONTINUE
TO LOOK QUITE STRONG.

THERE ARE OF COURSE THE USUAL INCONSISTENCIES BETWEEN FORECAST
MODELS WITH THIS STORM BEING 5-7 DAYS OUT, BUT HERE IS WHAT WE CAN
SAY AT THIS POINT REGARDING THE PRECIPITATION POTENTIAL.

IN GENERAL, WE ARE STILL LOOKING AT A VERY LARGE TROUGH IN THE
EASTERN PACIFIC THAT IS GOING TO PULL UP SUBTROPICAL MOISTURE TO THE
WEST COAST. MOISTURE WILL PROBABLY COME IN AT LEAST TWO SEPARATE
WAVES WITH POTENTIAL FOR A DECENT BREAK BETWEEN THEM. AREAS IN THE
NORTHERN SIERRA, NORTH OF INTERSTATE 80, HAVE THE BEST CHANCE OF
RECEIVING SIGNIFICANT PRECIPITATION. THE SOUTHERN SIERRA AND WESTERN
NEVADA STILL LOOK THE LEAST LIKELY TO SEE SIGNIFICANT
PRECIPITATION, WITH THE CENTRAL SIERRA THE MOST IN QUESTION.

CURRENTLY THE FIRST WAVE IS FORECAST TO COME THROUGH FRIDAY WITH THE
SECOND WAVE FOR LATER IN THE WEEKEND LESS CERTAIN. WHILE I DID
LOWER SNOW LEVELS ON FRIDAY NIGHT, AND THERE IS SOME CHANCE OF
SNOW CAUSING TRAVEL IMPACTS ON MOUNTAIN PASSES, SNOW LEVELS IN
GENERAL ARE GOING TO BE HIGH WITH THIS STORM AND COULD FLUCTUATE
BY A FEW THOUSAND FEET OVER THE WEEKEND.

SHORTWAVES ROUNDING THE BASE OF THE TROUGH ARE THE MAIN CULPRIT
CAUSING INCONSISTENCIES IN TIMING, SNOW LEVELS, AND THE SOUTHERN
EXTENT OF THE PRECIPITATION. IT IS TOO EARLY TO NAIL DOWN THESE
SMALL SCALE FEATURES EVEN THOUGH THEY DO HAVE THE POTENTIAL FOR
LARGE IMPACTS IN THE FORECAST. TOLBY

&&

.AVIATION...

VFR WITH LIGHT WEST WINDS TODAY BECOMING 10-15 KTS BY MONDAY
AFTERNOON. INCREASING MID AND HIGH LEVEL CLOUDS WITH SLIGHT CHANCE
OF PRECIPITATION DEVELOPING NEAR THE CA/OR BORDER LATER TONIGHT
THROUGH MONDAY NIGHT. TOLBY

&&

.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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