Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 032257
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
257 PM PST WED FEB 3 2016

.Synopsis...
Weak weather system will bring light snow down to 2000-4500 feet
through tonight. Another weak system is possible Friday night,
otherwise dry weather for the next week.

&&

.Discussion...
High pressure over the region this morning has quickly shifted
eastward as a high-amplitude trough approaches the West Coast.
This trough is expected to rapidly weaken over the next several
hours as it nudges into the upstream ridge. Highest precipitation
totals are expected across the Shasta County mountains,
diminishing quickly as you go south. Those Shasta mountains will
also see the highest snowfall totals as cold air remains trapped
in those river canyons. 2 to 5 inches will be possible along the
northern mountains, and only an inch or two of snow is expected
for the Sierra.

Dry weather is expected to return Thursday and Friday as the
eastern Pacific ridge quickly rebuilds into California. A weak
system is forecast to move across far northern California Friday
night into early Saturday, but at this point impact looks to be
minimal.

Dang

&&
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

Large scale pattern will be dominated by a highly amplified West
Coast ridge during the EFP. NAEFS and GEFS suggest a 30+ year return
interval in mid-level heights along the coast and primarily in
700-850 mbs temps. Strong subsidence and a lot of warm air aloft
will result in strong subsidence/temperature inversions. Thus...the
weather pattern is setting up for unseasonably warm wx with max
temps some 10-15 degrees above normal and potential for record max
temps for early Feb. The pattern is reminiscent of Feb 2006/2011.

Building high pressure will also result in surface pressure rises to
the NE of our CWA. Relatively strong offshore flow and N-NEly flow
will also result in katabatic winds and adiabatic warming effects
which could help boost max temps into record territory. Most of the
record temps in the Valley are in the 70s to low 80s during the
period.

925 mbs winds will be the most notable Sun into Tue morning before
weakening and transitioning to Sly. The Nly winds will preclude fog
formation early in the period...with the potential for patchy fog
in the Srn portion of the CWA during the latter half of the period.
   JHM

&&

.AVIATION...

Weak Pac fnt movs thru tngt with Wly flow alf vrg to NWly. Ovr
Cstl/Shasta mtns and in Cntrl Vly...lcl MVFR with isold IFR conds
poss tngt. For Wrn Plumas/Siernev mtns...areas MVFR/IFR/LIFR in
pcpn poss tngt into Thu mrng.


&&

.STO Watches/Warnings/Advisories...
Winter Weather Advisory until midnight PST tonight for Shasta
Lake Area / Northern Shasta County.

&&

$$


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