Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 182129
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
229 PM PDT Wed Oct 18 2017

.SYNOPSIS...

Dry conditions with above average temperatures will continue
through Thursday. A fast moving storm will bring windy conditions
Thursday afternoon and night, with colder temperatures and a
short period of valley rain and mountain snow Thursday night into
Friday. Warmer and drier conditions are expected for the weekend
and into next week.

&&

.SHORT TERM...

The main weather highlight for the upcoming week continues to be
the quick moving storm system which will bring windy conditions
Thursday afternoon and night, followed by a short period of rain
and higher elevation snow Thursday night into early Friday. Here`s
the latest details on this event:

Winds...All wind-related headlines will remain intact with peak
gust potential still up to 50 mph (65 mph in wind prone areas) in
the advisory areas, with Sierra ridge gusts near 100 mph. The
peak winds in valleys with greatest travel/boating impacts are
most likely to occur between 4-10 PM, with foothill/ridge winds
occurring a few hours longer on both ends of this time range.
Today is the day to secure loose outdoor objects and Halloween
decorations that are at risk for being blown over.

Precipitation...The moisture feed looks a little more organized
on the latest guidance, so we bumped precipitation chances and
amounts up a bit higher, with model guidance now indicating 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. Forcing along the
cold front looks to be sufficient for a quick burst of rain (up to
0.10 inch across far western NV including Reno-Carson), with
higher amounts up to 0.25 inch possible north of I-80. The bulk of
the precip is likely to occur between 10 pm and 5 am, with
forcing and moisture feed dropping off significantly by daybreak.

Snow Levels/amounts...Snow levels will begin quite high (above
9000 feet) at onset, then drop rapidly overnight to 5000-5500
feet for northeast CA and near 6000 feet around the Tahoe basin.
There is some uncertainty as to how much of the heavier precip
rates will occur in the cold sector, but a 1-3 hour period of
snow is a reasonable expectation with potential snowfall rates 1+
inch/hour. This could yield a couple of inches of snowfall west
of Susanville in northeast CA (near and above 5500 feet) and also
for Mono County near the crest including the higher passes (Sonora
and Tioga), while a few sites above 7500 feet around Tahoe could
receive up to 6 inches. Currently we are not planning any winter
weather headlines but there could be some slick or slushy roads
across most Sierra passes above 7000-7500 feet, and also on the
higher elevation routes west of Susanville such as Highways 36 and
44. Conditions will improve after daybreak as the precip tapers
off, but with temperatures slow to rise on Friday there may be
some slick patches on these higher elevation roads into the mid-
morning.

For the remainder of Friday, brisk and chilly conditions are
expected with isolated snow showers possible, mainly near the
Sierra and north of I-80 with no additional accumulations
expected.

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 enough cold air is likely to be present during this shortwave
passage.

.LONG TERM...Sunday and beyond...

Several quiet weather days are expected as ridge of high pressure
rebuilds over CA-NV early next week, then moves east across the
Great Basin by midweek. Temperatures will rebound quickly by
Sunday and remain above average through much of next week, with
highs mainly in the 70s for lower elevations. The Sierra valleys
will also become quite warm (highs near 70) as inversion
conditions set up, resulting in light winds and possible
reductions in air quality for some valleys. MJD

&&

.AVIATION...

VFR with light winds through Thursday morning. Then winds will
increase through the day with peak gusts at area terminals 30-40
kts after 21Z or so. Ridge winds will also see gusts increase to
60 kts at this time. Mtn wave turbulence expected, but LLWS is
unlikely through Thursday afternoon.

For Thursday evening and night, LLWS threat increases with high
confidence (>80%) of LLWS affecting KTRK/KTVL/KCXP/KRNO for a
period from 03-09Z. Mtn wave turbulence will also increase. Winds
begin to diminish after 09Z with turbulence and LLWS also
decreasing.

Late Thursday night between 06-12Z, the best chances for precip
will affect KTVL/KTRK/KSVE with a period of MVFR CIGS and mtn
obscuration. This precip could briefly change to -SN with IFR
CIGS/VIS at KTVL/KTRK before ending early Friday morning. A short
period of rain (2 hours or less) is becoming more likely to reach
KRNO/KCXP early Friday morning, although CIGS may not drop to MVFR
levels. MJD

&&

.FIRE WEATHER...

Poor humidity recovery will continue along mid-slopes and ridges
tonight before an incoming low pressure system provides strong and
gusty winds and increased moisture.

Winds will increase through the day on Thursday with the peak winds
occurring early evening and overnight in foothills and higher
elevations. This looks to be our first moderate level wind event for
the season but increased moisture arriving with this system will
help mitigate the development of widespread critical fire weather
conditions. The one area which could see a brief period of near
critical conditions may occur in southern Mono County where gusts
between 25-30 mph may be possible with RH near 15%. Thereafter,
moisture will continue to rise as the winds do overnight. Due to
lack of solid phasing of gusty winds and low humidity on Thursday,
have dropped the Fire Weather Watch that was in effect for Mono
County.

Winds will die off toward Friday morning and RH will then start to
recover quite well. Precip is also expected to move in as well.
Latest trends are showing a better chance for wetting rains (40-80%)
west of a line from South Lake Tahoe to Gerlach. Chances to the east
of that line will be low to non-existent. Fuentes

&&

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

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

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

     Lake Wind Advisory from 11 AM to 8 PM PDT Thursday for Pyramid
     Lake in NVZ004.

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

     Lake Wind Advisory from 11 AM Thursday 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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