Winter Storm Warning 5, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
326 PM PDT Tue Mar 25 2014

.Synopsis...
Wet and cooler weather will continue through the weekend.
Significant mountain snow and gusty winds are likely with possible
thunderstorms in the Valley.

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.Discussion...
Initial band of precip has passed through the area. The band
rapidly broke apart as it reached the southern sac and nrn San
Joaquin valleys. A more convective showery area of precip has
developed between Blue Canyon and Red Bluff. Current snow levels
are between 6000-5000 feet. Gave some thought to pushing the start
time for the winter storm warning back to after midnight. Will
instead keep the initial start time for areas north of highway 50
and push areas south of highway 50 back to 11 pm. This is due to
the uncertainty of convective development this evening as the HRRR
develops showers and thunderstorms Blue Canyon north. The next
trough will drop to along the coast after midnight with deeper
moisture and more significant precip streaming over the area
towards morning.

Moist westerly flow with embedded disturbances will continue
tomorrow with likely shower and thunderstorm chances. Valley qpf's
up to 0.50 inches will be possible with several inches of snow
above 5500 feet. Another disturbance will drop southeast in the
flow Thursday morning enhancing precip through the day.

Latest model runs shift the main precip a bit north on Friday with
best chances over the nrn sac valley. Have lowered pops over the
central and south and placed likely pops over the north and
mountains...as models show very good agreement in this solution.
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.Extended Discussion (Saturday through Tuesday)

Another stream of East Pacific moisture takes aim at NorCal for
the weekend, with the GFS showing modest PWATs about 1.1". A jet
streak will slide to our north under SW flow aloft with WAA and
insentropic lift over our area, supporting a band of light precip
across NorCal. Currently, models are suggesting this band will be
situated mostly north of I-80, so that area will have the best
chance of precip. Another shortwave trough is expected to slide
inland by early Sunday, shifting the band south across our entire
forecast area. This will bring widespread precipitation with snow
down to pass levels or lower and breezy winds. A brief break is
expected Sunday night into Monday, but the active pattern will
continue as another cold and wet trough moves onshore sometime
early next week. Extended models are in great agreement with
moving this next system into our area by late Monday. Bottom line
is a wet and generally cool pattern will continue with snow
levels below pass level at times. -DVC

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.Aviation...

Weak front moving through with showers behind. VFR/MVFR ceilings
with isolated to scattered showers tonight and showers should
increase aft 12Z Wednesday. Slight chance of thunderstorms
developing this evening north of Interstate 80 and Wednesday
afternoon at all TAF sites in the Valley, foothills, Delta and
Lake County. IFR with local LIFR conditions over the mountains. Snow
levels above 5500 feet dropping to around 4000 feet Wednesday
morning.

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.STO Watches/Warnings/Advisories...
winter storm warning until 11 am pdt thursday above 5500 feet in
the west slope northern sierra nevada...western plumas
county/lassen park.

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