Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 261030
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
330 AM PDT Sun Mar 26 2017

.Synopsis...
Pacific storm moves through today into Monday bringing
some rain and mountain snow. Drier Tuesday followed by a threat
of another storm midweek.

&&

.Discussion...
Pacific frontal system is approaching and will move through
Interior NorCal today into Monday. Models have slowed onset of
precipitation across the CWA with northern and western portions
seeing the best chances today. Bulk of precip modeled to move
across the CWA tonight with showers Monday, mainly over the
mountains. Storm total QPF amounts look to be less than half an
inch in the Central Valley with around half an inch to inch for
the foothills and mountains. Snow levels forecast to be around
4000 feet over the Shasta mountains, 4500 feet over Western
Plumas/Lassen Park, and 5500 feet over the Trans-Sierra passes
tonight during the peak precip period. Snow turns to snow showers
Monday morning as snow levels drop another 500 to 1000 feet. Snow
totals at this time appear to be upwards of around 3 to 6 inches
with locally up to a foot over the highest terrain. Have issued
a Winter Weather Advisory to cover this. Lighter snow amounts
possible over the higher terrain of Shasta county and the Coastal
range over the next 24 hours.  Some breezy conditions possible
this afternoon into evening but wind speeds remain below advisory
criteria.

Increasing subsidence over the area Monday night into Tuesday as
upper level ridging in EPAC pushes inland. Surface high also
builds inland across Oregon into the Great Basin. This will
increase the low level N-S pressure gradient over Interior NorCal.
Tightened surface gradient along with momentum transfer from
stronger winds aloft will result in some breezy northerly wind
over the CWA Monday night and Tuesday. Above normal temperatures
expected Tuesday with highs in the lower 70s for the Central
Valley with 50s to 60s for the mountains and foothills.

Models suggest ridging shifts east Wednesday as next Pacific storm
begins to spread some generally light precip north of a KUKI-KOVE-
KRTS line during the day. Precip threat increases over most of
the forecast area Wednesday night into Thursday.

PCH

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)
A fast moving clipper system is forecast to brush through the
region Thursday bringing a chance of showers, mainly to the
mountains. Impacts are expected to be minimal. Ridging from the
eastern Pacific will then build into NorCal for the remainder of
the week resulting in dry and milder weather along with locally
gusty north to northeast wind.

&&

.AVIATION...
Weather system moves through NorCal over the next 24 hours.
Valley TAF sites expected to remain VFR with local MVFR possible
vicinity showers 20Z-04Z Monday. Widespread IFR/MVFR conditions
developing over the mountains by 18Z. Local southerly winds 10-15
kts 18Z- 02Z Monday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 PM this afternoon to 5 AM PDT
Monday for Western Plumas County/Lassen Park.

Winter Weather Advisory from 8 PM this evening to 8 AM PDT
Monday for West Slope Northern Sierra Nevada.

&&

$$



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