Area Forecast Discussion
Issued by NWS Sacramento, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
000
FXUS66 KSTO 200507
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
907 PM PST Thu Jan 19 2017

.Synopsis...
A series of winter storms will move through NorCal through
Monday. Expect mountain travel impacts due to snow and winds.
Moderate to heavy rain at the lower elevations with windy
conditions.

&&
.Discussion...
The next storm system is spreading rain along the coastal range
and will continue to spread inland overnight. the heaviest rain
will move through late tonight and in the morning hours before
changing over to showers. Winds will increase late tonight and
early morning hours before decreasing by mid to late morning. The
strongest winds look to occur between 3 am and 9 am for the
valley. Winds generally 20 to 35 mph with gusts 35 to 50 mph.

Snow levels will remain fairly low with levels generally varying
between 3000 to 4000 feet...near 2000 feet over Shasta County.
They may raise a little during Friday morning over the Sierra
before decreasing Friday afternoon and Friday night. Thunderstorms
may also be possible behind the front...mainly for the afternoon
and night time hours but could linger into Saturday morning.
Snowfall through Saturday afternoon will be 2 to 3 feet near pass
levels.

The last system Sunday night into Monday will be the stronger of
the two with a little more precipitation for the valley with
similar snowfall total near the crest. Winds look similar to
Wednesday evenings event. Timing of the strongest/damaging winds
looks to be late Saturday night into early Sunday morning. Snow
levels may lower to near 1500 feet in Shasta County on Sunday and
near 2000 feet in the Sierra Nevada Sunday night. Colder air
filtering in the north may even bring snow levels a little lower
over Shasta County. Thunderstorms also look possible again behind
the front Sunday afternoon into Monday.
.Previous Discussion...
Showers and isolated thunderstorms will continue through the
evening...with a few heavier bursts of snow over the mountains.
Snow levels have dropped as low as as 3000 feet...but should
generally remain between 3500-4000 feet. South to southeast winds
will again increase around midnight under 45-55 kt 925 jet max.
This will translate to 30-35 mph winds with a few gusts to 50 mph
over the Sacramento valley Redding to Modesto into mid-day Friday.
These type of winds will likely down trees and power
lines...especially those weakened by yesterday`s strong winds.
Power outages will be possible late tonight and Friday morning.

Snow showers will continue over the Sierra this evening with a few
more inches...much heavier band will move in begining around 4 am
continuing into Friday with 1 to 3 feet possible above 4000 feet
through Saturday morning. Snow levels may dip to 3000 feet at
times in the heavier precip bands. Valley rainfall of 0.50 to 1
inch are forecast. Have added isolated thunderstorms to the Friday
afternoon forecast as enough clearing may open up for
destabilization over valley locations.

The next storm system will swing through NorCal Saturday night
into Sunday with valley rainfall of 1 to 2 inches and mountain
snow of 1 to 2 feet and snow levels 3000-4000 feet. Another round
of gusty winds with speeds to 50 mph will also be possible.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Transition to amplified upper air pattern forecast for next week
expected to give a break in precipitation to the region beginning
Tuesday. Until then, lingering upper trough will continue showers
across the region on Monday with accumulating snowfall likely
across the foothills and higher terrain.
&&

.AVIATION...

Interior NorCal will be in between stronger storms today with
showers continuing, most numerous over the mountains. Widespread
IFR conditions will continue over the mountains and north end of
the Sacramento Valley while VFR with areas of MVFR will
predominate elsewhere. Deteriorating conditions by 06Z Friday as
the next storm approaches. Southerly winds 10-20 kts today,
increasing to 15-25 kts with gusts 30-40 kts after 06Z Friday.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 AM PST Saturday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Winter Weather Advisory until 4 PM PST Friday for Mountains
Southwestern Shasta County to Northern Lake County-Shasta Lake
Area / Northern Shasta County.

Wind Advisory from 1 AM to 1 PM PST Friday for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

&&

$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.