Area Forecast Discussion
Issued by NWS Sacramento, CA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

505
FXUS66 KSTO 221036
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
236 AM PST Thu Feb 22 2018

.SYNOPSIS...
A cold system will bring low elevation snow to the mountains
into early Friday, which could impact travelers. A few showers are
possible in the Valley. Below normal temperatures will continue.
Additional systems likely next week.

&&

.DISCUSSION...
Still awaiting the first signs of precipitation on the radar as of
1 am. System has slowed but snow expected to begin over the
northern Sierra within the next few hours, reaching the I-80 and
Highway 50 corridors between 3 and 5 am. Snow levels will
generally be in the 1500-2000 foot range. Snow will continue
through the morning hours, impacting the AM commute and mountain
travelers. Another burst of snow is likely this afternoon and
evening during the PM commute, with lowering snow levels. Still
looks like this secondary wave of snow could bring a dusting down
to the lower foothills. Total accumulations remain generally
intact, with 3 to 6 inches above 2000 feet, locally up to 10
inches near the Sierra crest. Winter Storm Advisory remains in
effect through tonight. Travelers should check Caltrans road
conditions before they go, carry chains, and prepare for delays.
Visibilities may rapidly change over short distances especially in
bursts of heavier snow.

Meanwhile in the valley, latest hi-res guidance is indicating the
possibility of some pop up showers this afternoon and evening as
trough swings through NorCal. Hard to pinpoint where activity
might be as most areas will likely remain dry. Of note, NAM
showing CAPE values of 100-200 J/kg so also cannot rule out a
thunderstorm or two. These may drop some small hail with colder
air overhead. Breezy winds possible as system moves through.

System pushes east tonight with snow ending between 10pm and
midnight. Brief period of dry weather is expected Friday as
shortwave ridging moves in. Depending on how fast cloud cover
clears out, could be fairly chilly Friday morning with valley
temperatures dropping below freezing again. Next in a series of
shortwaves will drop south in NW flow Saturday. This will bring
another chance for mountain snow, mainly north of Highway 50
corridor. Moisture looks fairly starved with this wave so only
expecting light accumulations, but may be enough for some minor
travel impacts. Dry weather again Sunday with additional systems
likely next week. Temperatures will remain below normal.

CEO

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)
Active pattern is expected through the extended period as
successive disturbances embedded in the upper flow drop down from
the north. Guidance is still struggling with the progression of
these systems and precipitation amounts. Regardless, these systems
have the potential to bring precipitation, mountain snow, and
breezy winds. Given the cold nature of these systems, snow levels
will remain low.

&&

.AVIATION...
VFR conditions expected next 24 hours except local MVFR vicinity
scattered showers and thunderstorms 22Z-02Z and widespread IFR
over the northern Sierra with snow showers thru about 03Z Friday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 10 PM PST this evening for Burney
Basin / Eastern Shasta County-Motherlode-Northeast
Foothills/Sacramento Valley-West Slope Northern Sierra Nevada-
Western Plumas County/Lassen Park.

&&

$$



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