FXUS65 KREV 181119

Area Forecast Discussion
National Weather Service Reno NV
319 AM PST Fri Jan 18 2019


Cloudy and cool conditions will prevail today and tonight with a
chance of light rain and snow mainly north of Highway 50. Dry and
mild conditions return Saturday before another fast moving storm
moves across the region Sunday. Rain and high elevation snow will
begin across northeast California Sunday and spread to western
Nevada and the Sierra Sunday night. Brisk and cooler conditions
will follow Monday. A generally quiet pattern will then develop
for the remainder of next week.



Warm air advection was already initiating extensive cloud cover
this morning on the heels of the vigorous storm that brought heavy
rain and snow to the region Wednesday and Thursday. Model sounding
profiles show a gradual moistening aloft through the day with
sufficient forcing to produce light rain and snow, most pronounced
north of I-80 but as far south as Highway 50. Snow levels will be
on the rise by this evening as the warm front lifts northward. So
accumulating snow will be limited and should only cause some
brief travel issues for the northern Sierra and northeast CA. Rain
and snow will taper to showers overnight into early Saturday with
some breaks in the clouds for Saturday. Winds will be gusty
across ridges and in the Surprise Valley/far northwest NV where
gradients will tighten later today into tonight. Limited mixing
today will improve some Saturday as temperatures rebound into the
40s Sierra and 50s lower valleys.

For Sunday-Sunday night, the next storm will drop southeast into
the region with strong winds developing across ridges and gusty
surface winds leading to another mild day for lower elevations. A
lead shortwave pushes precipitation into northeast CA and
possibly the Tahoe Basin by midday Sunday where it will hang up
and wait for the main cold front and trough to push it out into
western NV and the rest of the Sierra down to Mammoth Sunday night.
Much of Sunday will see relatively high snow levels with rain at
lake level and even a mix possible up to the main passes around
Tahoe. As the front moves through Sunday night, snow levels will
fall quickly but precipitation too will taper behind the front. So
much of the snow accumulation will remain above lake level where
8 to 14 inches look reasonable. A couple of inches are possible at
lake level on the back side of the cold front. So travel will
deteriorate late Sunday into Sunday night for Sierra passes with
slick conditions to start the day Monday. QPF-wise, we are looking
at 1.00-1.25" along the crest in the Tahoe Basin tapering to
around 0.50" down by Mammoth. For the Tahoe Basin, 0.50-0.75" is
possible while 0.10-0.25" will prevail mainly with forcing along
the front across western NV. Hohmann

.LONG TERM...Monday through Thursday...

Only minimal changes were made to the extended part of the
forecast this cycle. There is some agreement in the overall
pattern...but there remains a fairly large difference in the
details as they pertain to the possibility of a slider-type system
by the Wednesday/Wednesday night time frame.

Monday should see residual snow showers as a trough exits to the
east. Gusty winds are likely east of the Sierra during the day...but
nothing worthy of an advisory. A ridge of high pressure builds for
Tuesday with light winds and drying.

Model agreement begins to break down Wednesday. The ECMWF...and most
of the GEFS ensemble members...take a fast moving short wave into
northeast Nevada late Wednesday afternoon. This would leave our area
dry. Meanwhile...the GFS brings this short wave farther west and is
slower. That would open our area up to the possibility of snow
showers late Wednesday evening into Thursday morning. Given most of
the ensemble solutions do not favor this scenario...we have opted to
keep snow showers east of our area Wednesday night and Thursday. We
will show a shift to northerly then easterly winds and a slight
cooling for Thursday.

The models often struggle with these types of features this far
out...so we may see multiple solutions over the next few days. That
makes this a low confidence forecast.



There should a period of decreased low cloud cover early today
with only a few lingering showers. Most of the area east of the
Sierra should remain VFR while conditions early this morning
favor MVFR in the Sierra. Winds aloft are starting to decrease so
turbulence...while still there...should decrease today.

By late this afternoon into this evening another round of
precipitation should develop north of Highway 50 with the best
chances north of a line from KTRK to KLOL. This precipitation is
likely to lower cigs and vsbys back into the MVFR range for much of
the northern Sierra...northeast California...and far northwest
Nevada. The heaviest precipitation may produce IFR conditions for
brief periods of time.

We should go back to VFR Saturday as a short wave ridge builds
briefly...but that is quickly replaced Sunday afternoon and
overnight by a fast moving storm system. This storm should bring a
return to IFR/MVFR conditions...stronger winds...accumulating snow
in the Sierra and northeast California...and possibly even a brief
period of light accumulating snow to terminals in the lower
valleys of western Nevada by Monday morning before showers end.


.REV Watches/Warnings/Advisories...


For more information from the National Weather Service visit...

NWS REV Office Area Forecast Discussion

Honor Flight NV - Honoring all of our Veterans CoCoRaHS (Community Collaborative Rain, Hail and Snow Network) Station Number: NV-DG-2 Live Lightning Map - USA Reno Skywarn Spotter ID: DO21 AlertID Southwestern Weather Network Carson Valley Community Food Closet - providing for the needs of our community