Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 220953
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
153 AM PST Fri Feb 22 2019

.SYNOPSIS...

A few very light snow showers are possible this morning along the
east and northeast facing slopes of the Sierra due to weak upslope
flow. weak high pressure will provide a break from the snow
saturday, but temperatures will remain below normal. We should
transition back to a more active pattern late in the weekend and
next week.

&&

.SHORT TERM...

The most significant lake enhanced snow showers have ended over
the region. We could still see a few showers through the morning
hours...but those will be more of the upslope variety as the low
level flow becomes northeast. Snow showers this morning will
favor the east and northeast facing slopes of the Sierra where
upslope potential will be maximized. Even so...accumulations will
be light.

A weak shortwave ridge develops tonight and Saturday. This should
lead to rather cold conditions again as we see a mainly clear sky
for all but areas near the Oregon border. This ridge presses east
rather quickly and we then transition to a more zonal flow aloft.

A strong west-northwest to east-southeast jet develops Sunday
morning to our north. This should focus the best forcing with the
next system near and north of the Oregon border. Model simulations
have been slowing the southward progression of this feature.
While we will continue to indicate at least a chance of precipitation
across the northern half of the forecast area late Sunday...we
will show the best potential in northeast California and far
northwest Nevada. A shortwave trough approaching the coast by late
Sunday night will start the process of pushing precipitation
chances farther south as lift ahead of the trough increases...but
this will happen more in the extended portion of the forecast.

With the best forcing to the north...we do expect temperatures to
warm a bit to more typical readings for late February by Sunday.
As the jet begins to sag south by late Sunday...gusty winds may
begin to develop across the region as well.

.LONG TERM...Next week (Monday through Saturday)...

Few changes made except to lower chances a bit in the Sierra Monday
and overall precip amounts a bit, except near the Oregon border.
Models continue to show differences in the system for Monday through
Wednesday with the 00Z GFS an outlier and extremely wet while the
EC/NAM are drier/farther north. The GEM and FV3 are a compromise
being a bit farther south and wetter, but not nearly as wet as
the GFS. The forecast overall with go with an EC/GEM blend to go
on the drier side of things, but not too dry. That said, while I
am not using the GFS, its solution is still plausible, although
unlikely. A couple outlier runs from 5 days out were close to
verifying the wet Feb. 13-14th system.

A general trend is having the main front draped near the Oregon
border Monday, sag south a bit Tuesday before lifting back north
Wednesday. Snow levels will lift off the valley floors along the I-
80 corridor, but the Surprise Valley may not see them rise much
depending on the location of the front. It could either be a bunch
of rain, or heavy snow there. To give an idea of the range of
solutions for moisture, the Sierra Crest in Tahoe could see as
little as 1/2 inch or more than 5 Monday through Wednesday. The
official forecast is in between these extremes, about 2-2.5 inches.
This gives us maximum flexibility for changes going forward, not
that I think it has the best chance of verifying out of the range of
possibilities.

There will be a short wave ridge after it moves through with mild
temperatures, a few degrees above average for a change. The dry
period looks to be Thursday-Friday. Then another mild system moves
in for next weekend. It continues to look active into the first week
of March. X

&&

.AVIATION...

Snow showers today will be mainly limited to the KMMH area as weak
upslope develops in the eastern Sierra. MVFR conditions are still
possible this morning for KTRK and KTVL...but these conditions
will improve through the day. With some clearing overnight...we do
look for a high likelihood of freezing fog around KTRK late
tonight and early Saturday. Right now the chances are about 70%.

VFR conditions and light winds develop for Saturday. By late
Sunday the next area of low pressure begins to lower cigs/vsbys
and develop light rain/snow near the Oregon border and down into
northeast California and northwest Nevada north of I-80. Gusty
west-southwest winds also begin to develop with a return of
turbulence aloft.

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

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


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