Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 250939
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
239 AM PDT Sat Mar 25 2017

.SYNOPSIS...
Another spring storm will move across the Sierra and western
Nevada Sunday into Monday with travel impacts possible for the
Monday morning commute in the Sierra. Breezy winds may create
choppy lake conditions through the weekend. After a weak storm on
Thursday the pattern appears to trend drier and warmer for the end
of next week and next weekend.

&&

.SHORT TERM...
The main trough has dropped south out of the region for today but
it looks like the secondary trough will push across early this
morning. Overall the secondary trough will likely produce some
convective rain/snow showers for the Sierra and western Nevada
early this morning and intermittently through the afternoon. The
HRRR and NAM are hinting at a more substantial-looking band
developing just before sunrise this morning across the Tahoe
Basin, Interstate 80 corridor, and extending into Reno. If the
band develops it could result in a quick couple inches of snow
for locations above 5500 feet. Any snow accumulation should melt
off relatively quickly as the convective showers dissipate.

The next storm continues to trend drier and less impressive for
Sunday night into Monday. Forecast simulations are showing
warm air advection precipitation mainly north of a Susanville and
Lovelock line, but even that initial wave of moisture is looking
less cohesive than previous model runs. The bulk of the
precipitation is still forecast to push in late Sunday night into
early Monday morning. Although it has been trending drier, any
rain/snow during the Monday morning commute could result in some
travel delays. The NAM has been more dramatic in downplaying this
storm, while the GFS is still hinting at some potential for
banding by midday Monday. Snow amounts will be a little less than
the last storm with around 5-7 inches possible above 7000 feet.
Although it will be cold enough to snow down to 5500-6000 feet on
Monday morning, snow accumulation will be limited below 6500 feet
due to warmer road surfaces and the ground resulting from a
higher late March sun angle.

After that storm pushes through there will be some residual
showers through the day along with the best chances south of
Highway 50 as the low drops southward. -Edan


.LONG TERM...Tuesday through Friday...

Very minimal changes were made to the inherited long term forecast
this morning. The trend in the model solutions has remained roughly
the same...but the details still vary enough between the operational
models to keep forecast confidence in the low to medium range for a
mid-week system.

The period starts with a weak short wave ridge over the region which
should allow high temperatures to rise to slightly above normal for
Tuesday. After that the operational models differ with the next
short wave trough. The ECMWF is much faster and a little farther
west in bringing the trough into the northern part of Nevada by
early Thursday. The GFS is slower and drops the trough into
northeast Nevada by late Thursday. Both have trended farther
northeast with this low/trough. The GFS has more ensemble support.
With the operational models still showing differences in their
respective solutions regarding track and timing...have opted to
leave the forecast for late Wednesday into early Friday largely
unchanged. Some slight adjustments were made to raise snow levels
and low temperatures early Thursday in deference to the slower GFS.
That seems to be the trend to follow.

Track and timing of the upper low/trough will make all the
difference in whether areas along the far western edge of the CWA
see any precipitation at all. For now we will have slight chance to
low chance pops for most of the region Wednesday afternoon into
early Friday. Temperatures may need to be lowered Thursday if the
low/trough tracks farther west.

A ridge begins to develop again by late Friday into the overnight
hours Friday night and for next weekend.

&&

.AVIATION...
Showers linger in parts of the forecast area early this morning in
the wake of an upper level trough and associated surface front that
moved through the area Friday. This will result in periods of MVFR
to IFR conditions in the Sierra this morning...but no significant
snow accumulation at any area terminals. Winds should be lighter
today than Friday.

A short wave ridge develops later today...then moves well east by
Sunday afternoon. Another storm system will move through the region
Sunday night into Monday morning with periods of IFR conditions in
the Sierra and northeast California. Some snowfall is likely at the
higher elevation terminals by Monday morning. In the lower valleys a
brief period of rain or a rain/snow mix is possible by Monday
morning. Gusty winds will also develop late Sunday night ahead of
this system.

&&

.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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