Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 211122

Area Forecast Discussion
National Weather Service Reno NV
322 AM PST Wed Feb 21 2018


Winter weather will continue to impact the region with a series
of cold winter storms through at least next week. The first
tonight through Thursday will likely bring widespread light to
moderate snowfall throughout the region. Most areas will see a
break in snowfall through the weekend with a another stronger
storm possible Monday/Tuesday next week.



Widespread snow accumulation in the Sierra and western Nevada is
expected late tonight through Thursday evening. The main message
today is that you should be prepared for the potential for
significant travel impacts to both the morning and afternoon
commutes on Thursday in western Nevada. Snow advisories have been
issued throughout the region for light to moderate snowfall. For
specific snow amounts for each region please refer to the Winter
Weather Advisory.

Winds aren`t expected to be very strong with this system, but
with very cold temperatures in place wind chill will be a serious
concern, especially in the high Sierra where wind chill
temperatures could again be as low as -20 degrees Thursday into
Friday. Keep in mind that at that temperature the risk for
frostbite occurs within 30 minutes.

A fairly classic `slider` storm is forecast to move through
western Nevada on Thursday. One big difference with this storm
vs. many of the previous slider systems we have seen this year,
and maybe even for the last couple years, is that very cold air
(-14C at 700mb, around ridge top level) is already in place. This
will create very deep instability and produce much higher snow
ratios than we have seen for a long time. Also, with light snow
ratios and breezy winds Thursday morning, low visibility due
blowing snow can be expected, especially in the Sierra.

Sliders are a challenge to forecast, and are highly dependent on
exact track (<50 miles) of the upper level wave, so I`ll try to
give break it into a few scenarios. If system tracks a little
farther west it would favor higher snow accumulations in the
Sierra with lower snow accumulations in western Nevada. And if the
system moves just a little east the opposite would be true. With
the highly convective nature of the precipitation it is also
possible a few areas could see much higher snow amounts, but it is
impossible to say where that might be. With all that said, still
think there is a good chance that western Nevada will see
widespread snow accumulations of a couple inches that will likely
cause travel disruptions throughout the region. -Zach

.LONG TERM...Saturday through next week...

Winter continues into next week! The Pacific ridge continues to pull
away, allowing more shortwaves to drop into the Western U.S. through
the weekend and into next week. These waves will bring reinforcing
shots of cold air to the region, along with chances for snow.

Forecaster confidence is high that we will remain unsettled through
next week, although models have been struggling with timing and
details. While none of these systems look to change our huge Sierra
snowpack deficit, they will likely bring periods of moderate snow
to the region next week. Anyone with travel plans next week
should check back with the forecast as periods of winter driving
conditions are likely. These slider type systems typically become
clearer 2-3 days ahead of time, and then we can have better
specifics about timing and snow amounts. For now, it does look
like the weekend will be the best time to travel over the Sierra
with deteriorating conditions as we go into next week.

The next storm system that comes in Monday-Tuesday has been showing
a bit further offshore trajectory that would allow this cold trough
to pick up a little more Pacific moisture before coming into the
region. Snow levels would be at all valley floors, along with a
strong cold front that will drop temperatures even further by the
middle of next week. The active weather pattern is expected to
continue through the first week of March as the longwave pattern
remains locked-in over North America bringing cold shortwaves down
from the Gulf of Alaska and into the West Coast. -Hoon



VFR conditions (just higher clouds) are expected through today with
a few light flurries in the Sierra.

The next storm system/cold front moves into the region tonight
into Thursday, bringing widespread light to moderate snow to the
region, including the lower elevations in northeast CA and western
Nevada. Breezy winds along the front, along with moderate snow
will bring periods of MVFR/IFR CIG/VIS to the area terminals,
especially Thursday morning and with a second round Thursday

Storm total snow amounts for KTRK-KTVL will be around 3-6 inches
with the biggest impacts to CIG/VIS being , with about 1-3 inches
expected for KRNO-KCXP, as well as KMMH. Snow accumulations are also
likely for KNFL-KHTH-KLOL with up to 1-2 inches possible. -Hoon


.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 8 PM this evening to 4 PM PST
     Thursday NVZ005.

     Winter Weather Advisory from 2 AM Thursday to 4 AM PST Friday

     Winter Weather Advisory from 10 PM this evening to 10 PM PST
     Thursday NVZ002.

     Winter Weather Advisory from 2 AM to 10 PM PST Thursday

CA...Winter Weather Advisory from 8 PM this evening to 4 PM PST
     Thursday CAZ070-071.

     Winter Weather Advisory from 2 AM Thursday to 4 AM PST Friday

     Winter Weather Advisory from 10 PM this evening to 10 PM PST
     Thursday CAZ072.



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