Winter Storm Warning 8, NWS Sacramento, CA

Area Forecast Discussion
National Weather Service Sacramento CA
1221 PM PDT Thu Mar 22 2018

.SYNOPSIS...
Wet weather continues with chances for afternoon thunderstorms
today. Active weather will continue into the weekend. Snow levels
will begin lowering today with significant accumulations at the
higher elevations into the weekend.

&&

.DISCUSSION...

Bands of narrow heavy precipitation have formed over the forecast
area this afternoon and continue to bring heavy precipitation to
the valley and foothills. Many reports of flooded roadways, parks,
and local streams have been reported across the area earlier this
morning and afternoon. Latest short term high resolution guidance
suggests lines of heavy precipitation and isolated thunderstorms
are likely to develop this afternoon. Chances for small hail,
gusty winds, funnel clouds and a tornado or two cannot be ruled
out this afternoon as atmospheric dynamics favor storm
development.

Rain and heavy mountain snow will begin Friday, especially during
the afternoon and evening hours. Travel is expected to become very
difficult for the mountain passes, especially after 4 PM Friday.
Snow accumulations between 3 to 4 feet are possible for higher
elevations with snow levels dropping between 1500 feet for the
mountains north of Redding to the 2500-3000 feet for the Sierra.

Chances for wet weather will continue through Sunday before dry
weather returns to the area.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)

Building high pressure will bring an end to any precipitation
threat by Monday morning. Clearing skies and warming airmass
under the ridge will bring warmer temperatures but highs are still
forecast to run slightly below normal. Upper level and surface
gradients indicate breezy north winds which will help to start
drying things out. Temperatures continue to warm on Tuesday as
upper ridge pushes inland with highs expected to warm to slightly
above normal. Pressure gradients weaken slightly but breezy north
winds are still expected. Even more warming is expected on
Wednesday under light north wind conditions with highs throughout
the valley expected to reach the upper 60s to lower 70s or several
degrees above normal. Daytime highs Thursday reach to between 5
and 10 degrees above normal as high pressure settles in over the
region with lighter north breezes continuing.

&&

.AVIATION...

Mainly MVFR/IFR conditions TAF sites as a Pacific storm system
pushes through the region. Mainly IFR over mountains. Snow levels
dropping to 4000 to 6000 feet by this afternoon. Valley
thunderstorms possible 18z today to 00z Friday. Mainly VFR
conditions after 03z Friday. Southerly winds with gusts 20 to 35
knots northern in the Central Valley, 40-50 knots over the higher
Sierra. Winds decreasing after 06z Friday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 11 PM PDT this evening for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.

Winter Storm Watch from Friday morning through late Saturday
night for Burney Basin / Eastern Shasta County-Shasta Lake Area
/ Northern Shasta County-West Slope Northern Sierra Nevada-
Western Plumas County/Lassen Park.

Flash Flood Watch until 11 PM PDT this evening for Motherlode-
Northeast Foothills/Sacramento Valley.

&&