000
FXUS66 KSTO 071207
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
407 AM PST Sat Dec 7 2019



.SYNOPSIS...
A strong winter storm will bring periods of heavy rain, mountain
snow, strong winds, and hazardous travel this weekend. Dry
conditions return next week with near average temperatures.

&&

.DISCUSSION...
The closed low is currently sitting at 130W this morning with one
embedded disturbance moving into southern OR. Radar imagery does
show a quite a few showers over interior NorCal, with the bulk of
the precip currently located over NW CA. Expect to see increasing
chances for precip again later today as the next wave moves in.
This will bring periods of moderate to heavy rain and mountain
snow, along with the chance for some Valley thunderstorms.
Instability, shear, LI, and a favored vort max support the chance
for storm activity. HREF probabilities continue to high light the
potential for over a half inch of rain an hour for portions of
the foothill and Valley regions. Some blesses form over Lake and
Butte counties in particular, thus we kept the Flash Flood Watch
going for the the Carr/Hirz/Delta, Camp, and Mendocino Complex
burn areas.

For those also, or perhaps more interested in the snow forecast,
snow levels are expected to be around 6500-7000ft throughout most
of the day, but will slowly be falling this evening. The profiler
at Colfax this morning depicts snow levels around 7500ft. Expect
to see moderate to heavy mountain snow over the Sierra Nevada
today, especially for areas above 6500ft. Significant travel
impacts are expected. Gusty winds may create near white out
conditions at times in combination with heavy snowfall rates. Snow
levels do drop slightly by early Sunday morning as the low moves
over NorCal, with snow down to about 5500-6000ft. Feet of snow are
still expected by the end of this system. The Winter Storm
Warning continues through early afternoon Sunday.

Finally, we can expect to see breezy winds continue in the
Valley through much of the morning and into the early afternoon
hours. Wind gusts of 30-45 mph will be possible, mainly for the
northern portion of the Sacramento Valley.

Looking to Sunday, showers will linger over the area with the
possibility for some isolated thunderstorms, mainly south of HWY
36. As the mid level wave pushes out of NorCal chances for precip
will dwindle, with drier weather expected for the evening.
Ridging returns Monday with average temperatures and dry weather
expected through Tuesday.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...

Ensemble guidance continues indicate zonal flow across the eastern
Pacific later next week with ridging across NorCal. The pattern
will bring potential for light warm-advection precipitation
across the northern mountains, but the remainder of the area will
likely remain dry. Temperatures will be slightly above average.

&&
&&

.AVIATION...

Widespread MVFR, with local IFR, conditions next 24 hours as
Pacific storm system continues to bring showers to the region.
Southerly surface wind gusts 25-35 kts, strongest over the
northern Sacramento Valley, gradually tapering after 00Z Sunday.
Isolated thunderstorms possible 18Z-00Z accompanied by small hail
and surface wind gusts to 45 kts. Snow levels 6500-7500 ft.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this afternoon for 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.

Winter Storm Warning until 1 PM PST Sunday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Wind Advisory until 1 PM PST this afternoon for Carquinez Strait
and Delta-Central Sacramento Valley-Mountains Southwestern
Shasta County to Northern Lake County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

&&

$$