Lake Wind Advisory 17, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
217 AM PDT Sun Mar 26 2017

.SYNOPSIS...

The next spring storm will move across the Sierra and western
Nevada today into Monday with travel impacts possible for the
Monday morning commute in the Sierra. Breezy winds may create
choppy lake conditions through the weekend. Storm on Thursday
may bring additional rain and snow to the Sierra and western
Nevada.

&&

.SHORT TERM...

The next spring storm is still on track to move into the Sierra
and western Nevada later today. No big changes were made to the
forecast with the primary concerns being snow for the Sierra
passes late tonight into early Monday morning and choppy
conditions on Monday for Pyramid Lake.

There may be some light warm air advection precipitation early
today, but it appears that much of it will be either right along
the Oregon border or along the Sierra crest. The bulk of the
precipitation moves into the Sierra after 6pm which will result in
a period of moderate to heavy snow for elevations mainly above
6000 feet. The main cold front pushes through in the morning where
snow levels may drop down to around 4500 feet for northeast CA.
Bottom line: If you are traveling back from a ski weekend in the
mountains you will want to plan on leaving before this evening to
avoid slowdowns and delays due to the snow moving into the Sierra.

Simulations have continued to be on the drier side, but with the
sufficient moisture and colder air there will be some snow
accumulations by Monday morning. For areas above 7000 feet,
including the passes, we are forecasting between 5 to 7 inches.
Although we could see some light snow into western Nevada with
brief periods of spillover, it appears that we will be dealing
with wet roads Monday morning. Some areas like the foothills above
Reno and Carson City, the north valleys of Reno and Virginia City
could see a couple of slushy wet inches, so plan on leaving
plenty of time for your morning commute.

Monday will be brisk as westerly flow transitions to northerly
flow behind the cold front. There may be a few leftover showers
Monday afternoon with the cold core of the low over north central
Nevada, but overall precipitation chances will be on the decrease.
As the area of low pressure pulls away and allows ridging to build
in across the region, the Sierra and western Nevada should
experience a bit of a warming and drying trend. This will be
relatively short-lived as the next system approaches the area for
late Wednesday into Thursday. -Edan

.LONG TERM...Wednesday Night through Saturday...

Primary changes made to the long term forecast involve increasing
pops/QPF for the Thursday time frame while lowering pops/QPF a
little for Wednesday evening. This is all in response to operational
models starting to converge toward a solution by Thursday. There are
still some differences in the solutions...and the models still have
plenty of time to go off the rails...but for now forecast confidence
is starting to increase in a system dropping south-southeast across
the Great Basin Thursday.

The leading edge of this system begins to affect areas near the
Oregon border Wednesday evening. The surface front slides south by
early Thursday and crosses the forecast area by Thursday
afternoon. Snow levels were adjusted down a little for Thursday
afternoon...but raised slightly ahead of this low. Overnight lows
for Wednesday night into Thursday morning were also raised as
winds should not decouple overnight. Highs Thursday may be early
in the day as well...prior to frontal passage.

The ECMWF is still a bit more aggressive with the upper low/trough
Thursday...carving it farther west and dropping it south faster than
the GFS. The Canadian and most of the GEFS ensemble members tend to
favor the GFS solution. The GFS is trending farther west than
previous runs...so we will see how this plays out. We increased pops
during the day to account for better lift/forcing along the front
and with the upper low. Instability parameters support a slight
chance of thunder over far northwest Nevada and the basin and range
country of western Nevada Thursday afternoon/evening. QPF is still a
bit of a question. Normally an overland trajectory would not be
conducive for significant precipitation amounts...and that is how we
have it for now. But the highly convective nature of the system
could produce brief heavy bursts of precipitation east of Highway 95
Thursday.

The upper low exits to the southeast slowly Friday morning with a
few lingering showers over parts of Pershing/Churchill/Mineral
counties. A ridge begins to build after that with mild air returning
by Saturday. This will bring above normal temperatures for the
weekend if the GFS and its ensemble members are correct...for now
the ECMWF is producing another low that drops south across the
forecast area next Sunday. This is in contrast to ridging on the
GFS.

&&

.AVIATION...
Mountain obscurations expected this morning with increasing cloud
cover through the day as the next spring storm moves into the
Sierra and western Nevada. Light snow showers will be possible for
Sierra terminals by daybreak, but main push of precipitation will
not move in until after 0z today. Winds will increase through the
day today with surface gusts generally up to 30 kts. For the
Sierra ridges, wind gusts could be around 65 kts, leading to
increased risk for mountain wave activity and turbulence.

This storm will move through quickly with periods of snow
producing IFR conditions in the Sierra and northeast CA. For the
lower valleys into western NV there could be a brief period of
rain or a rain/snow mix by Monday morning as the cold front moves
through.

A dry period Tuesday and Wednesday gives way to another system
Thursday that drops south across the region. Showers and possibly
thunderstorms are expected with this system. -Edan

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

For more information from the National Weather Service visit...
http://weather.gov/reno