Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 150848

Area Forecast Discussion
National Weather Service Reno NV
148 AM PDT Thu Mar 15 2018


A stronger and colder storm moves into the region by Thursday
afternoon and continues through Saturday morning. This storm will
produce additional periods of heavy snow in the Sierra with snow
accumulation also likely for lower elevations. Lighter showers
may continue through the rest of the weekend, then dry weather is
likely through at least Tuesday morning ahead of the next storm



The next winter storm is on track to bring serious travel impacts
to the Sierra, northeast CA, and western NV starting this
afternoon and evening. The better period for avoiding snow over
the main passes (including I-80 and US-50) is to complete the trip
by noon today. This is a moderate storm by Sierra standards but
the travel impacts in the Sierra will be fairly long lasting --
from late this afternoon through Saturday morning.

Forecast snow totals for this storm (Thursday afternoon through
Saturday morning) were not changed this morning. The forecast
still calls for 2-3 feet of snow for the Tahoe Basin above 7000
feet, with some locations along the Sierra Crest around Tahoe
potentially seeing up to 4 feet. For the Sierra valleys below
7000 feet, roughly 1 to 2 feet are expected, including around
Lake Tahoe, Truckee, and Portola. There is also high confidence
for heavy snow through Lassen-Plumas over this time period.

Snow will spread south across Mono County this evening. thus
there is potential for travel impacts along US-395 starting this
evening, but the period of heaviest snow in Mono county is
expected Friday afternoon through Friday night. For Mono County
west of US-395, we still expect roughly 1-2 feet but with 2-4 feet
possible near the crest.

For Lassen-Washoe-Carson locations below 5000 ft, spillover snow
is likely tonight into Friday. Confidence is lower for snowfall
totals for this region because snow rates don`t look to be as
high, and because surfaces will be warm enough to melt snow this
evening. For storm totals this evening through Friday -- on the
low end we expect 1-3 inches but on the high end there is
potential for 4-8 inches. For locations in this region above 5000
ft, including Virginia City, confidence is higher for storm totals
in the 4-8 inch range.

As for the valleys of west-central Nevada, we could also see light
snow accumulations Thursday Night into Friday morning, 1-3 inches
expected for Fernley-Fallon-Lovelock-Yerington-Hawthorne. Should
see some decent instability this afternoon and Friday afternoon in
western Nevada and northeast California as well, with potential
for an isolated embedded thunderstorm.

The low-pressure trough will be overhead Saturday afternoon.
While steady snow is not expected, the trough overhead should
leads to "hit and miss" instability showers, some of which could
quickly create an inch or two of snow in less than an hour. A
drying trend is expected to ensue starting Saturday night as the
upper trough exits to the east. JCM

.LONG TERM...Sunday through Wednesday...

Only very minor changes were made to the extended forecast through
early Tuesday morning. There are likely to be a few lingering
showers Sunday in northeast California north of Highway 70 as a very
weak impulse tries to push into the region.

By Monday the GFS is developing a ridge over the region that results
in a dry day with some warming and rising snow levels. But now the
ECMWF is trying to drop a weak slider-type trough into the Great
Basin Monday. It mainly affects the central and eastern portions of
Nevada...but if this were to come to pass we could see at least
increased clouds and lower high temperatures. This is the first time
the ECMWF has generated this solution...and it has almost no support
from the GEFS ensemble suite. For those reasons we will keep Monday
dry and trend toward the GFS solution.

Beyond Monday...the operational models differ on the timing of the
next system forecast to impact the region Tuesday into Thursday.
Because the ECMWF develops the ridge later than the is much
slower bringing the initial part of the storm into the region...
favoring Wednesday as opposed to Tuesday. The GFS is faster...but it
is also a little slower than previous runs indicated. This makes
some sense as the GFS ridge is holding on a bit longer Monday night
into early Tuesday morning. Thus...we have cut back POPs early
Tuesday and confined them mainly to the high Sierra. We let the
precipitation chances spread east and northeast Tuesday night into
early Wednesday.

The trajectory of this system favors warmer air overall and higher
snow levels. It appears to be tapping into a fairly deep moisture
plume and so QPF was increased...especially for Wednesday through
Thursday. While this system appears as though it could be a
significant precipitation producer...the chances of being a
prodigious snow maker are fairly low given snow levels potentially
rising above 5500-6000 feet in northeast California...above 6500-
7000 feet around the Tahoe basin..and above 7500 feet for Mono

It is early...and confidence on exact liquid precipitation and snow
amounts is low at this time...but confidence is starting to increase
in a mild and wet storm the middle of next week.



A winter storm arrives to the Sierra this afternoon and to western
NV this evening and overnight. This is a moderate storm by Sierra
standards but is fairly long lasting, creating snow impacts from
Thursday afternoon all the way into Saturday morning. For KTRK and
KTVL expect snow showers this afternoon with lowering ceilings
and visibility becoming LIFR by 00z Friday. The period of
strongest winds in the Tahoe Basin will be Thursday evening into
Friday morning, when blowing snow will create near zero
visibilities at times.

Snow will spread south along the Mono County crest this evening
but with lower confidence for when snow will spill over to KMMH.
There are chances for showers at KMMH starting late this evening,
but with the best chances for steady snow not until Friday evening
through Saturday morning.

At KRNO and KCXP, MVFR conditions are likely this evening by
around 03z. Confidence is high in seeing snow but is only medium
for snow amounts. Lighter snow rates and warm pavement may limit
snow accumulation until Friday morning. One to two inches of snow
could accumulate by early Friday morning. However, we also can`t
rule out more intense snowfall rates at times which could create
storm totals around 6 inches by Friday afternoon. JCM


.REV Watches/Warnings/Advisories...
NV...Winter Storm Warning from 2 PM this afternoon to 5 AM PDT
     Saturday NVZ002.

     Winter Storm Warning from 8 PM this evening to 11 PM PDT Friday

CA...Winter Storm Warning from 2 PM this afternoon to 11 PM PDT
     Friday CAZ071.

     Winter Storm Warning from 8 PM this evening to 11 AM PDT
     Saturday for Lake Tahoe in CAZ073.

     Winter Storm Warning from 2 PM this afternoon to 5 AM PDT
     Saturday CAZ072.



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