Area Forecast Discussion
Issued by NWS Sacramento, CA

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913
FXUS66 KSTO 212044
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
144 PM PDT Tue Mar 21 2017


.Synopsis...
A series of weather systems will bring cooler and more unsettled
weather to the region this week. Chance of thunderstorms this
afternoon and Wednesday.

&&

.Discussion...
Enough clearing occurred this morning to allow for the development
of thunderstorms across the Valley late this morning-early
afternoon. As of noon, main orientation was linear from about
Oroville south to Lodi. This line was causing torrential rainfall
with localized flooding on roadways. Several reports of over a
half inch of rain falling in less than 30 minutes in Sac metro
area. As indicated by hi- res guidance over the past few days,
more discrete cells are popping up across the northern San Joaquin
Valley. Primary concern is hail with gusty winds, though still
cannot rule out a brief tornado or two where best instability and
low-level shear lie.

Precipitation becomes more showery late this evening and tonight.
Another line of moderate precipitation looks to move through
early Wednesday morning as upper level trough moves overhead.
Timing again looks favorable for some thunderstorms in the Valley
during the afternoon hours. At present indications, this activity
looks like it won`t be as strong as today`s. Snow levels will fall
to around 5000 feet with several inches of accumulation likely
near pass levels. This is bound to cause a few travel headaches so
travelers should carry chains and be prepared for delays.

Short-wave ridging briefly builds in for Thursday with a break in
precipitation across most of the area and a bit of sunshine ahead
of the next approaching system for the end of the week!

CEO

&&

.EXTENDED DISCUSSION (Friday THROUGH Tuesday)
Friday into early next week shows another stormy pattern setting
up for interior NorCal. The most significant storm wave will be
Friday into Saturday which will have similar rain and snow amounts
to our current Monday- Tuesday system...around half an inch to
over an inch of rain in the valley with a few inches up to a foot
of snow over the Sierra, Lassen Peak, and Shasta County mountains.
Snow levels around 5000 feet. Winds could be breezy to locally
gusty on Friday as the front passes. Temperatures will be about 5
to 10 degrees below normal. Showers diminish on Saturday into
early Sunday. Then another weak storm wave could move inland
Sunday evening into Monday morning. An upper level ridge will
build on Monday, which will bring a return of mostly dry weather
for the valley and warming temperatures.

&&

.AVIATION...
Isolated thunderstorms expected through the afternoon with light
rain after 6Z for KRDD, KRBL, KSMF, and KSAC. Southerly winds with
gusts 20 to 30 kts in the valley through 6Z. VFR conditions
expected.

HEC

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 6 PM PDT
Wednesday for Western Plumas County/Lassen Park.

Winter Weather Advisory until 6 PM PDT Wednesday for West Slope
Northern Sierra Nevada.

&&

$$



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