Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 312302
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
302 PM PST SAT JAN 31 2015

.SYNOPSIS...

HIGH PRESSURE IS BUILDING INTO NORTHERN CALIFORNIA AND NEVADA THIS
WEEKEND WITH GUSTY NORTHEAST WINDS CONTINUING ACROSS SIERRA RIDGES
THROUGH THIS EVENING. MILD CONDITIONS ARE EXPECTED THROUGH THE
MIDDLE OF THE UPCOMING WEEK WITH A SMALL CHANCE FOR LIGHT
PRECIPITATION ACROSS NORTHERN CA/NV EARLY IN THE WEEK. THERE IS A
BETTER CHANCE FOR UNSETTLED WEATHER BY THE END OF THE WEEK.

&&

.SHORT TERM...

A POSITIVELY TILTED RIDGE IS BUILDING INTO THE NORTHWEST, FLANKED
ON EITHER SIDE BY LOW PRESSURE CENTERS, ONE IN THE GULF OF ALASKA
AND THE OTHER DROPPING INTO THE DESERT SOUTHWEST. GUSTY NORTHEAST
RIDGE WINDS WILL CONTINUE THROUGH THIS EVENING IN BETWEEN THE
NORTHWEST RIDGE AND THE SOUTHWEST LOW, BECOMING LIGHT OVERNIGHT.
THE STRONGEST WINDS ARE ON SOUTHERN SIERRA RIDGES, WITH THE
MAMMOTH MOUNTAIN SUMMIT REPORTING GUSTS AROUND 100 MPH MUCH OF THE
MORNING, DECREASING TO AROUND 75 MPH EARLY THIS AFTERNOON. AS
WINDS WEAKEN AND WITH CLEAR SKIES TONIGHT, RADIATIONAL COOLING
WILL BE MAXIMIZED WITH OVERNIGHT LOWS IN THE TEENS AND 20S.

THE RIDGE FLATTENS MONDAY IN RESPONSE TO SEVERAL WEAK SHORTWAVES
PUSHING INTO THE PACIFIC NORTHWEST. THESE PIECES OF ENERGY ARE NOT
ESPECIALLY DYNAMIC AND THE DEEPEST MOISTURE REMAINS NORTH IN THE
PACIFIC NORTHWEST. HOWEVER, THE TREND HAS BEEN TO BRING SOME
MOISTURE FARTHER SOUTH, SO HAVE INCREASED POPS SLIGHTLY MONDAY AND
TUESDAY, BUT KEPT TOTAL PRECIP AMOUNTS LOW, WITH MEDIUM CONFIDENCE
ON THE SOUTHERN EXTENT. THERE WILL BE ABUNDANT CLOUD COVER, BUT
DESPITE THIS TEMPERATURES WILL REMAIN QUITE MILD, IN THE 60S IN
MOST LOWER ELEVATION VALLEYS AND 40S AND 50S IN THE MOUNTAINS.
WITH TEMPERATURES THIS MILD IT IS NO SURPRISE SNOW LEVELS ARE
GOING TO BE HIGH, MAINLY 7000-8000 FEET. THEREFORE, THERE WILL BE
LITTLE IF ANY IMPACT FROM ANY SHOWERS THAT DO DEVELOP. DJ


.LONG TERM...WEDNESDAY THROUGH SATURDAY...

MAIN CHANGES TO THE LONG TERM FORECAST TODAY WAS TO INCREASE WINDS
FOR FRIDAY. OTHERWISE STILL EXPECTING A RETURN OF MOISTURE TO THE
WEST COAST THIS COMING WEEKEND AS A STRONG LOW PRESSURE SYSTEM
IN THE EASTERN PACIFIC DRAWS IN SUBTROPICAL MOISTURE. AFTER ONE OF
THE DRIEST JANUARY`S ON RECORD, MOISTURE WILL BE A WELCOME SIGHT IN
CALIFORNIA, HOWEVER THE MAIN PLUME OF MOISTURE IS EXPECTED STAY
MOSTLY DIRECTED AT NORTHERN CALIFORNIA. THE SUBTROPICAL MOISTURE
TAP WILL KEEP SNOW LEVELS AROUND 8000 FEET, WHICH WILL DO LITTLE
TO HELP THE SIERRA SNOWPACK.

RIDGING OVER THE SIERRA WILL PEAK ON WEDNESDAY WITH HIGH CLOUDS
BEGINNING TO WORK INTO THE REGION. WEDNESDAY AND THURSDAY WILL SEE
TEMPERATURES REACHING THE MID 60`S IN WESTERN NEVADA WITH
INCREASING CLOUDINESS.

CURRENT GFS RUNS BRING A ROBUST MID LEVEL JET INTO THE SIERRA ON
FRIDAY AHEAD OF MAIN MOISTURE PLUME. THIS ALONG WITH INCREASING
SURFACE GRADIENTS COULD MAKE FRIDAY A VERY WINDY DAY ALONG AND
EAST OF THE SIERRA.

NOW FOR A LOOK AT PRECIPITATION POSSIBILITIES. THE GOOD NEWS IS
THERE IS ACTUALLY A RELATIVELY WIDE PLUME OF PWAT 1.5" OR MORE
POINTED AT NORTHERN CALIFORNIA THROUGH THE WEEKEND ALONG WITH THE
RETURN OF THE JET STREAM WHICH MANAGED TO AVOID CALIFORNIA FOR THE
WHOLE MONTH OF JANUARY.

THERE ARE A FEW THINGS WORKING AGAINST THE SIERRA AND WESTERN NEVADA
RECEIVING SIGNIFICANT PRECIPITATION. DURING THE HEAVIEST
PRECIPITATION THE SIERRA WILL REMAIN ON THE WARM SIDE OF THE JET.
THIS WOULD LIMIT SPILLOVER PRECIPITATION AND KEEP SNOW LEVELS AT
MID-MOUNTAIN OR HIGHER. THERE IS ALWAYS THE POSSIBILITY THAT A
SHORTWAVE COULD BRING IN SOME COLD AIR OR THAT HEAVY PRECIPITATION
COULD BRING DOWN SNOW LEVELS FOR A SHORT PERIOD OF TIME. MODELS TEND
TO HAVE A SOUTHERN BIAS WITH ATMOSPHERIC RIVERS IMPACTING THE WEST
COAST WHICH INCREASES UNCERTAINTY IN THE SOUTHERN EXTENT OF THE
MOISTURE. IT ALSO LOOKS LIKE THERE WILL BE A SHARP GRADIENT IN
PRECIPITATION WITH AREAS IN NORTHERN CALIFORNIA RECEIVING
SIGNIFICANT PRECIPITATION AND SOUTHERN CALIFORNIA RECEIVING LITTLE
OR NO PRECIPITATION, ALTHOUGH IT`S TOO EARLY TO TELL EXACTLY WHERE
THAT LINE WILL BE. TOLBY

&&

.AVIATION...

VFR CONDITIONS AT ALL TERMINALS THROUGH THE WEEKEND WITH HIGH LEVEL
CLOUDS INCREASING FROM NORTH TO SOUTH ON SUNDAY. GUSTY E-NE RIDGE
WINDS OVER THE SIERRA WILL BRING PERIODS OF TURBULENCE, BUT THESE
WILL BECOME LIGHT OVERNIGHT. OTHERWISE, WINDS WILL BE LIGHT E-NE
TODAY, SHIFTING TO THE WEST ON SUNDAY. 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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