Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 112158

Area Forecast Discussion
National Weather Service Reno NV
258 PM PDT Sun Mar 11 2018


Drier conditions are expected tonight and Monday. A stronger
system will bring gusty winds, rain, and snow Tuesday and
Wednesday. Unsettled conditions will continue into the weekend
with additional storms possible. Temperatures will be near
average through the early portion of this week before falling
below average late in the week.



We had some pretty widespread freezing fog last night over the
region, with some areas struggling to break out this afternoon.
It`s possible we will see another round of freezing fog and
stratus tonight, especially over the Tahoe Basin and northeast
California valleys where there is still a bit of stratus and fog
hanging around. Monday should be a beautiful Spring-like day
across the region with highs reaching into the upper 60s across
western Nevada and 50s in the Sierra.

The next storm system begins to move into the region Monday night
into Tuesday, with high forecaster confidence for increasing
winds, mountain snow and a mix of valley rain and snow. Winds
start to increase Monday with gusts up to 20-30 mph, then winds
become gusty on Tuesday as the cold front pushes into the region
with gusts up to 40 mph along the Sierra Front.

Winter Storm Watch has been issued for the Tahoe Basin and Eastern
Sierra of Mono-Alpine Counties for snow Tuesday into Wednesday.
Precipitation pushes into the Sierra Tuesday morning and
continues through Wednesday morning as the main jet stream moves
over the region. Snow levels will start out near 7500 feet ahead
of the cold front on Tuesday. Snow levels drop behind the cold
front late Tuesday afternoon and into Tuesday evening down to near
valley floors 4000-5000 feet. The worst conditions for traveling
over the Sierra will be Tuesday evening as slick roads and chain
controls will be likely during this time over the Sierra.

Overall, snow totals Tuesday into Wednesday will be heaviest
along the Sierra Crest above 7000 feet. This storm will have
pronounced south flow ahead of the front that will really limit
the amount of precipitation in the lee of the Sierra, especially
before the front moves through Tuesday afternoon. Also, below
7000 feet, there will be much less snow accumulation as snow
levels won`t be coming down until towards the end of the
precipitation event. It`s possible that we could see a dusting of
snow in the valleys of western Nevada by early Wednesday morning,
but that still is low confidence and remains to be seen.
Additional shortwaves will move through the region Wednesday for
additional snow amounts mainly in the Sierra. -Hoon

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

While the weather will be unsettled, rainy, and snowy for much of
the week, there will be a couple different time frames where travel
conditions may become unruly: (1) Wednesday afternoon and evening as
well as (2) Thursday afternoon through Friday morning. Since we are
well into March, daytime snow showers would have to be quite
significant to affect road travel, so generally road conditions will
be worse after sundown than during the day. Stay up-to-date on road
conditions this week as they may vary significantly from day to day.

(1) Wednesday afternoon and evening -- showers may seem somewhat
continuous in the Sierra from the previous wave on Tuesday as the
next wave of moisture pushes into the Sierra and northeast
California. The upper level jet associated with this moisture
appears to dip far enough southward that we end up on the colder
side of the jet, which would mean lower snow levels (4500-5500 feet).

(2) Thursday and Friday -- This is the main big boom or bust time
frame. Model simulations are trending colder and wetter this
morning, but there is still quite a bit of uncertainty associated
with that round of moisture. The latest GFS and ECMWF are pinning a
deformation zone across Tahoe and into western Nevada by Friday
morning. There is potential for heavy snow in the Sierra as well as
some wet snow `down here` in western Nevada. Keep in mind, this
solution is off course from previous model solutions, so we won`t be
completely biting on it yet. If the low tracks westward in future
simulations, the Sierra and western Nevada will not be underneath
that prime deformation zone where the best snow potential and
intensity would occur. That being said, Thursday-Friday will be a
critical time frame to keep an eye on through this week, since in
typical spring fashion we could get a lot or very little.

Takeaway: Definitely monitor the forecast through the week,
especially if you have travel over the Sierra.



There is a chance that we could see some fog at KTVL-KTRK tonight,
although we are expecting some high clouds to move in tonight that
may limit fog formation. 50% chance of seeing MVFR/IFR CIGS/VIS
tonight at those locations. Even less chance of seeing fog at
KRNO-KCXP-KMMH tonight and into Monday morning, less than 20%

Winds increase Monday with gusts 20-25 kts ahead of the next cold
front moving into the region. Ridge winds increase further Monday
night above 40-45 kts likely resulting in light to moderate
mountain wave turbulence along the Sierra Front. South flow aloft
will also bring concerns of low level wind shear Monday night into
Tuesday. Conditions further deteriorate by Tuesday afternoon and
evening as the cold front moves through the region. -Hoon


.REV Watches/Warnings/Advisories...
NV...Winter Storm Watch from Tuesday afternoon through Wednesday
     afternoon NVZ002.

CA...Winter Storm Watch from Tuesday afternoon through Wednesday
     afternoon CAZ072-073.



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