Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 191024
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
324 AM PDT Thu Oct 19 2017

.SYNOPSIS...

A fast moving storm will bring windy conditions this afternoon
and tonight, with colder temperatures and a short period of
valley rain and mountain snow tonight into Friday. Warmer and
drier conditions are expected for the weekend and into next week.

&&

.SHORT TERM...
Current satellite imagery shows a deep low near the British
Columbia coast and a cold front moving into the Pacific Northwest
shifting southward. The forecast is on track for strong winds
this afternoon and tonight ahead of the approaching cold front.
There will also be a short period of higher precipitation rates
tonight with the frontal passage, mainly in northeast CA and in
the Sierra.

Expect peak gusts in northeast CA and in the lee of the Sierra up
to 50 mph in general, but up to 65 mph at wind prone locations.
(Wind prone locations include Highway 395 between Susanville and
the NV/CA border, along I-580 in the Washoe Valley, and also for
foothill locations around Reno, Carson City and Minden.) Drivers
on Highway 395/I-580 should be prepared for strong cross winds.
Lake wind advisories remain in effect for Lake Tahoe and Pyramid
Lake for wave heights up to 4 feet starting this afternoon.

Latest computer simulations continue to show a few hours of
heavier precipitation tonight between 10 PM and 5 AM as the cold
front quickly moves through. For locations that transition to
snow, snowfall rates 1+ inch/hour are possible for 1-3 hours
during the frontal passage. Snow levels are forecast to fall
overnight to 5000-5500 feet for northeast CA, to 6000-6500 in the
Tahoe Basin. Depending on how quickly rain turns to snow, there is
potential for a couple of inches of snowfall west of Susanville
in northeast CA (near and above 5500 feet), and in the Tahoe
Basin for 2 to 6 inches above 7500 feet. Less moisture is
transported into Mono County, but at the higher passes (Sonora and
Tioga) and for higher elevations on Mammoth Mountain, several
inches of snow are very possible.

The bottom line is to be prepared for some slick or slushy roads
across most Sierra passes tonight above 7000-7500 feet, and also
on the higher elevation routes west of Susanville such as Highways
36 and 44.

For total liquid precipitation amounts, expect around 0.50 inch
with locally up to 0.75 inch along the Sierra crest west of Tahoe
and into northeast CA west of Susanville, and 0.25-0.50 inch for
the rest of the Tahoe basin. For western NV, expect up to 0.10
inch across far western NV including Reno-Carson City, with higher
amounts up to 0.25 inch possible north of I-80.

Precipitation should taper off to showers early Friday morning,
but isolated snow showers could create slick patches at times
Friday on Sierra roads. Winds decrease but remain breezy in
valleys Friday, and will continue to be very strong across
ridges especially in Mono County.

On Saturday, a shortwave moving across the Pacific Northwest will
bring warm advection cloud cover to much of the region, with very
light precipitation possible north of Susanville and Gerlach. A
dusting of snow could fall in the Surprise Valley Saturday morning
as cold air is likely to remain deep enough for snow in the
valley during this shortwave passage. JCM

.LONG TERM...Sunday through next week...
A quiet, mild week is still on tap for next week. High pressure is
expected to settle over the Sierra by Monday with warm temperatures
and light winds. Areawide temperatures will likely be in the 70s,
from the mountain valleys to lower valleys. Even ridge and mountain
top temps below 10,000 feet will get into the 60s next week. The
ridge is showing some signs of breaking down toward the end of next
week, but how and when are yet to be determined. At least until
then, temperatures will average 10 to 15 degrees above average
during the day with records in the mountains not out of the
question. With the dry air in place, overnight lows will be
seasonable due to strong radiational cooling.

&&

.AVIATION...
Concern today will be the winds with gusts from the southwest to 35
kts at area terminals. Then tonight, winds will continue to be an
issue along with precip moving into the Sierra. Detailed concerns
for the terminals are grouped below:

KRNO/KCXP: LLWS will be the main concern and be prevalent through at
least 07Z. SFC winds will remain more south with SW winds off the
deck. After 07Z, moisture increasing will cut the winds a bit and
they are also expected to become more SW, aligned with the winds
aloft. Chances of seeing any MVFR CIGS is only 20-30% and focused
from 10-13Z.

KTVL/KTRK: Winds will continue to gust through 06Z with LLWS due to
channeling especially near KTVL. After 06Z, sfc winds will diminish
some as precip moves in. It is expected to be mainly in the form of
rain with MVFR CIGS from 07-12Z (80% chc). It will mix with and
change to -SN as it ends around 12Z, but no runway accumulation is
expected. LLWS will also wane after 12Z behind the cold front as
winds aloft weaken and sfc winds become more aligned with them.

KMMH: Winds to be gusty here, but also expecting them to be more
aligned with winds aloft. Therefore less LLWS is expected, but it is
still not out of the question. Peak gusts to 40 kts could occur from
02-09Z here. Little if any threat for CIGS/VIS restrictions as the
moisture is expected to rapidly thin before making it this far south.

For Friday, some gusty west winds up to 30 kts, but then winds are
expect to diminish by Saturday with VFR conditions for all
terminals.

&&

.FIRE WEATHER...
Winds still look to increase this afternoon and continue through
this evening. Latest model trends continue to show more moisture
with this system so the threat for critical conditions is much
diminished. That said, localized areas could see a brief period
of Red Flag conditions for 1-3 hours. The most likely place for
this to occur would be along 395 in Mono County south of Lee
Vining.

Wetting rains are likely for the Sierra west of 395 and also north
of Gerlach in Western Nevada. Further east and south, the threat
remains low with many areas in Western Nevada south of I-80 not
seeing a drop.

&&

.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 3 PM this afternoon to 5 AM PDT Friday NVZ005.

     Lake Wind Advisory from 11 AM this morning to 5 AM PDT Friday
     for Lake Tahoe in NVZ002.

     Wind Advisory from 3 PM this afternoon to 5 AM PDT Friday NVZ003.

     Lake Wind Advisory from 11 AM this morning to 8 PM PDT this
     evening for Pyramid Lake in NVZ004.

CA...Wind Advisory from 3 PM this afternoon to 5 AM PDT Friday
     CAZ070-071.

     Lake Wind Advisory from 11 AM this morning to 5 AM PDT Friday
     for Lake Tahoe in CAZ072.

&&

$$

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



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