Winter Storm Warning 10, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
825 AM PST Thu Dec 11 2014

.Synopsis...
A Strong Pacific storm impacts the area into Friday bringing
heavy precipitation including significant mountain snow and strong
winds. A mainly dry weekend is expected with the next chance of
precipitation early next week.

&&

.Discussion...
Strong Pacific storm impacting NorCal this morning. Satellite
imagery showing deepening low center, near 977 mb, about 130 nm
off the southern Oregon coast with associated frontal system
extending through WA/OR/CA. Baroclinic zone tapping into
atmospheric river extending from CA southwestward into Hawaii.
Blended TPW showing PWs peaking near 1.8 inches along the NorCal
coast. Very tight pressure gradient extends from low center
through Central Cal. Warm sector precip has occurred overnight
with strong SE winds. As a result, strong isentropic lift and
favorable orographics into the Shasta basin have lead to
impressive rainfall amounts with some rain gauges reporting over
4.5 inches of rain with about 2.5 inches at Redding ASOS. KRDD
also reported a wind gust at 63 mph this morning as the cold front
moved into the area. Farther south, near the Bay Area, several
NCFR (narrow cold frontal bands) seen on radar along leading edge
of cold front indicating strong low level southerly jet. Both the
KBBX and KDAX VAD profilers showing 65 kt SE winds at 2K ft above
the surface. Strongest winds expected along the front this morning
as it moves inland with downed trees and power outages continuing.

Heavy precip over the northern CWA attm will spread south and
east today as the atmospheric river sags south over the CWA. Urban
flood warning issued for northern/northwestern portions of the CWA
already and additional ones likely for the southern half latter
this morning. Instability progs indicating thunderstorm chances
today look unlikely.

Very strong winds occurring in the mountains this morning with
KBLU reporting a gust to 69 mph. Snow levels however remain high
attm, above 8000 feet, but will gradually lower from north to
south today into tonight as colder air is ushered into the area.
3KM HRRR showing heaviest precip in the Lassen Park/Western Plumas
area through 00z Friday and over the Northern Sierra Nevada this
afternoon into tonight. Snow levels will lower to around 4000 to
5000 feet by Friday morning with several feet of snow expected
over the higher terrain.

Front drops south of the CWA tonight then associated upper trough
moves through Friday keeping unstable conditions over Interior
NorCal. Showers and isolated thunderstorms expected with best
instability depicted over the Coastal range, Delta and Southern Sac
Valley into the San Joaquin Valley. Trough axis moves through
Friday night then upper ridging progged over the weekend with
drier weather and valley fog.

PCH

&&

.Extended Discussion (Monday through Thursday)

Ridge shifts off to the east Monday ahead of an offshore upper level
trough that will swing into the area Monday into midweek. As
several waves drop SE in the flow, chances for precipitation will
return. Model differences remain in timing and strength of trough
and associated shortwaves so have continued with chance of precip
through midweek. The system will be weaker than this week's with
less precip but colder with lower snow levels. Valley daytime
temps will be in the 50s with 30s to 40s in the foothills and
mountains. CEO

&&

.Aviation...

Strong Pacific front offshore will be moving inland today. Wet
and very windy conditions will spread over the TAF sites today.
Already MVFR cigs/vsbys in RDD/RBL will spread over Sac area and
SCK TAF sites during afternoon and evening. Main band of moderate
to heavy rain will cause IFR conditions. Southerly winds
increasing over TAF sites peaking between 15z-20z with gusts up
to 55 kts possible in the Valley. Airport Weather Warnings have
been issued for Redding and Stockton Airports for the winds. IFR
and areas of LIFR conditions developing over the Siernev obscuring
terrain. Snow levels 7000-8000 ft lowering to around 5000 ft
Thursday evening.

&&

.STO Watches/Warnings/Advisories...
high wind warning until 2 pm pst this afternoon west slope
northern sierra nevada...western plumas county/lassen park.

flood watch through friday evening burney basin / eastern shasta
county...central sacramento valley...clear lake/southern lake
county...mountains southwestern shasta county to northern lake
county...northeast foothills/sacramento valley...northern
sacramento valley...shasta lake area / northern shasta county...
western plumas county/lassen park.

flood watch through friday evening carquinez strait and delta...
motherlode...northern san joaquin valley...southern sacramento
valley...west slope northern sierra nevada.

blizzard warning until 4 am pst friday above 6500 feet in the
west slope northern sierra nevada.

high wind warning until 2 pm pst this afternoon burney basin /
eastern shasta county...carquinez strait and delta...central
sacramento valley...clear lake/southern lake county...
motherlode...mountains southwestern shasta county to northern
lake county...northeast foothills/sacramento valley...northern
sacramento valley...northern san joaquin valley...shasta lake
area / northern shasta county...southern sacramento valley.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
846 AM PST THU DEC 11 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0846 AM     NON-TSTM WND DMG AUBURN                  38.89N 121.08W
12/11/2014                   PLACER             CA   PUBLIC

            DOWNED TREE KNOCKED OUT POWER LINE.

&&

NWS SACRAMENTO CA
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
859 AM PST THU DEC 11 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0855 AM     FLOOD            LAKEPORT                39.04N 122.92W
12/11/2014                   LAKE               CA   NEWSPAPER

            MINOR ROAD FLOODING TO NUMEROUS ROADS.

&&

NWS SACRAMENTO CA
IRIS SYSTEM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
933 AM PST THU DEC 11 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0933 AM     NON-TSTM WND DMG 3 NW FLORIN             38.53N 121.44W
12/11/2014                   SACRAMENTO         CA   PUBLIC

            DOWNED TREE.

&&

NWS SACRAMENTO CA
IRIS SYSTEM

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