River Flood Warning 6, NWS Sacramento, CA

Area Forecast Discussion
National Weather Service Sacramento CA
1121 AM PST Sun Jan 8 2017

.Synopsis...
Heavy rain, gusty winds, and flooding concerns today. Flooding
concerns continue Monday into Wednesday with very heavy mountain
snow expected. Another weather system possible Thursday.

&&

.Discussion...
Moderate to heavy precipitation has spread across most of the area
this morning, except for southern portions of the northern San
Joaquin Valley. A few isolated thunderstorms have developed in the
Motherlode and have added these to the forecast.

There have been reports of minor flooding, trees down, and local
power outages associated with this storm, mainly in the Mother
Lode area. Voluntary evacuations continue on Yuba River near
Simpson Lane, and along the Cosumnes River by Wilton.

The main band of precipitation will gradually track southward
through the afternoon with heavier rain rates expected. The
Valley will see generally decreased precipitation by this
evening, though some thunderstorms may develop behind the main
band. Heavy precipitation will continue in the mountains
overnight, gradually decreasing in intensity.

Winds have also steadily been ramping up this morning across the
Valley, 20-25 mph with gusts up to 30 to 45 mph being reported.
Trees have been reported down, with some power outages, especially
in the Motherlode. Winds may pick up in the early afternoon,
before decreasing late in the afternoon.

Main concern shifts to heavy snow on Monday as snow levels lower
below pass levels in the morning, below 5000 feet by afternoon. Snow
amounts of 3 to 5 feet are possible in the Sierra, potentially
more. Major impacts to travel are expected, and will likely
upgrade the Winter Storm Watch to a Warning.
&&
.EXTENDED DISCUSSION (Thursday THROUGH Sunday)

Large level in uncertainty in the extended forecast as models
continue to struggle. Looks like wet pattern extends at least into
Thursday with GFS and ECMWF showing some level of troughing over
the west while GEM shows overrunning precip ahead of a more
offshore trough solution. High chance pops seem appropriate at
this time with moderate snow levels. Forecasting wind direction
nearly impossible with all models showing different scenarios but
at least strong winds are not indicated. GFS and ECMWF show drying
on Friday under upper ridge but GEM keeps things quite moist
bringing a moderately moist system across the coast. Have left in
chance pops for now but could see a change to a drier solution if
model solutions become more consistent. Models actually become a
little more consistent with each other going in to next weekend
showing a fairly flat ridge over the west and overrunning
precipitation moving into the region at least by the end of the
day Saturday. Again, have kept chance pops in for now but details
still fuzzy. GFS and ECMWF agree on continued break down of any
ridge by next Sunday so at least chance pops will remain in the
forecast for second half of next weekend.
Not much change in the extended forecast. Wednesday continues to
look wet as that is part of the second wet storm expected to hit
NorCal on Tuesday-Wednesday with snow levels below passes at
approximately 4000-5000 feet. The models continue to struggle on
how the wet pattern will look between Thursday through Saturday.
At this point, it looks like Thursday will at least see some
scattered showers (GFS), but it could be more widespread (ECMWF).
Both models are showing a break Friday with an additional storm
arriving either early Saturday (GFS) or late Saturday (ECMWF).
Chance pops continue to be best bet at this time. Snow levels
remain moderate through the extended period. JBB

&&

&&

.AVIATION...

MVFR/IFR ceilings and visibilities are expected next 24 hours as
another system moves onshore. Moderate to heavy rain at times. Strong
south winds 20 to 30 gusts to 40 mph south of Sacramento
spreading northward over much of area by mid morning. Gusts over
50 mph over Sierra. Winds decreasing in the valley after about
03z. Heaviest precipitation moving into Sierra after 06z.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Wednesday afternoon for 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-West Slope Northern Sierra
Nevada-Western Plumas County/Lassen Park.

Winter Storm Watch from late tonight through Wednesday afternoon
for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

Wind Advisory until 6 PM PST this evening for Carquinez Strait
and Delta-Central Sacramento Valley-Clear Lake/Southern Lake
County-Motherlode-Northern Sacramento Valley-Northern San
Joaquin Valley-Southern Sacramento Valley.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
1102 AM PST SUN JAN 8 2017

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

1000 AM     HEAVY RAIN       1 N QUINCY              39.94N 120.92W
01/08/2017  M3.50 INCH       PLUMAS             CA   TRAINED SPOTTER

            24 HOURS.

&&

IDM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
1136 AM PST SUN JAN 8 2017

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

0800 AM     HEAVY RAIN       1 E QUINCY              39.92N 120.90W
01/08/2017  E2.52 INCH       PLUMAS             CA   TRAINED SPOTTER

            2.52 INCHES RAIN SINCE 8:00 PM. LOW WATER
            CROSSINGS FLOODED.

&&

IDM