Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 230349
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
849 PM PDT Sat Apr 22 2017

.UPDATE...

Winds are decreasing on schedule on Pyramid Lake but remain rather
strong around Lake Tahoe. A couple of buoys on Lake Tahoe are
still in the 15 to 25 mph sustained range. A few land sites around
the lake are gusting into the 25 to 35 mph range as well. Thus we
have extended the Lake Wind Advisory for Tahoe until 11 pm. All
indications are the winds will begin to decrease after that time.
We will allow the Lake Wind Advisory for Pyramid to expire at 9
pm.

No other changes to the current forecast. A weak wave is lifting
east-northeast across northern California and southern Oregon.
Most of the forcing and deeper moisture is north of the Oregon
border tonight so pops were left out of the forecast.

&&

.PREVIOUS DISCUSSION... /Issued 218 PM PDT Sat Apr 22 2017/

SYNOPSIS...

A couple of weak systems brushing to the north today and Sunday
are bringing breezy winds and periods of clouds, with light
showers possible north of Susanville and Gerlach Sunday. For the
first part of next week, additional systems will bring gusty winds
with light shower chances spreading farther south. Temperatures
will ease down to near or slightly below average next week.

SHORT TERM...Through Tuesday Night...

Our short-lived ridge is already shifting eastward as one weak
shortwave moves through the Pacific Northwest today, followed by a
second weak system shifting through the northwest Sunday. This will
bring increased winds and high level clouds to the region, but any
precipitation chances should be limited to near the Oregon border,
with meager totals. Northwest flow will usher in multiple shortwave
for the early part of the week, keeping cool and breezy conditions
in place along with chances for showers.

Breezy southwest winds this afternoon will weaken overnight, but may
not fully decouple, especially for higher elevation valley
locations. Upper level winds are not quite as strong on Sunday as
they are today, but the surface gradient is stronger. This is likely
to lead to slightly stronger sustained winds Sunday compared to
today, but less of a speed/gust spread. As the jet moves over the
eastern Sierra and northern Nevada Monday into Tuesday, it will
bring a further increase in wind speeds. Monday looks to be the
windiest day at this point, with surface wind gusts of 30 to 45 mph
and ridge gusts of 80 to 90 mph likely. Winds will bring choppy
conditions to area lakes over the next several days, in addition to
periods of mountain wave activity for aviation.

The trajectory of the jet stream and position of the main area of
low pressure well to the north will lead to the best precipitation
chances north of I-80 Monday into Tuesday. These waves are fairly
progressive and lack organization this far south, so precipitation
totals should be minimal. Generally a couple tenths up to a third of
an inch is possible for the Sierra and northeast California with one
to two tenths in the Tahoe Basin. For western Nevada and Mono
County, totals up to a few hundredths are likely for some locations,
while others will not receive any rainfall. Locations closer to the
Oregon border, such as the Warner Mountains, could see upwards of a
half inch Sunday through Tuesday. Outside of Monday night into
early Tuesday morning, snow levels will be high enough to keep all
but the highest Sierra passes clear.

These systems will also bring several degrees of cooling each day
through the early part of the week. Highs Sunday will return to near
normal, then fall a few degrees below normal Monday into Tuesday.
- Dawn

LONG TERM...Wednesday through next weekend...

The large scale pattern next week will feature a trough developing
in the Great Basin and over the Rockies with ridging building into
the southeastern Pacific. The pattern will become more amplified
through the week as additional shortwaves dig into the Great Basin
deepening the trough into the Southern Rockies.

Wednesday and Thursday will remain cool with lingering showers
possible Wednesday. Wednesday and Thursday could also be quite
breezy as cold fronts push through from the northwest.

Daytime high temperatures will remain below average through most of
the week with highs in the upper 50`s to mid 60`s in western Nevada
and upper 40`s to low 50`s in the Sierra. Hard freezes become less
common this time of year in western Nevada and aren`t expected this
week, but temperatures could near freezing in colder valleys for a
Wednesday-Friday. For early season gardeners and late season skiers
in the Sierra, hard freezes will become likely again for a few days
at the end of next week as clouds clear out and the upper level cold
pool remains over the Great Basin.

The storm track continues to stay active in the Pacific Northwest
next weekend which will keep the ridge from amplifying over the
western U.S. Currently looks like next weekend could be similar to
this weekend with above average temperatures limited to just a few
days. Precipitation is looking unlikely next weekend, however, the
ridge is showing signs of retrograding west which could allow fast
moving cold fronts from the north back into the region by the first
week of May. -Zach

AVIATION...

Widespread VFR conditions are anticipated throughout the weekend
with increasing high level clouds and breezy winds both surface
and aloft. Gusty winds this afternoon will weaken overnight, but
may not fully decouple for KTRK, KTVL, and KMMH. Winds will return
Sunday, with slightly stronger sustained winds, but lighter wind
gusts likely as compared to today. Satellite observations are
indicating mountain wave activity downwind of the Sierra today,
with these conditions to continue into Sunday. A few light showers
are possible near the Oregon border on Sunday, but otherwise the
eastern Sierra and western Nevada will remain dry though the
weekend.

Stronger winds look likely Monday into Tuesday with scattered
showers. Please see the short term section above for additional
details. -Dawn

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 11 PM PDT this evening for Lake Tahoe
     in NVZ002.

CA...Lake Wind Advisory until 11 PM PDT this evening for Lake Tahoe
     in CAZ072.

&&

$$

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


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