Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 312110
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
210 PM PDT Tue Mar 31 2020

.Synopsis...
Dry and mild weather expected this week. Breezy north winds expected
tomorrow and Thursday. A storm moves in over the weekend into early
next week bringing chances for rain, mountain snow, and gusty winds.

&&

.Discussion...
Light scattered showers are noted across the northern mountains
early this afternoon, with these showers expected to continue this
evening spreading over portions of the Southern Cascades and Sierra
north of I-80. Valley highs are expected to reach into the upper 60s
and low 70s this afternoon with cloud cover continuing to decrease
in this area.

Showers are expected to end by late tonight with dry weather
continuing through Friday. Some breezy north winds are expected both
tomorrow and Wednesday as a system passes to the north and east,
increasing pressure gradients across NorCal. Gusts from 25-35 mph
will be possible each day in the Valley.

A shortwave progresses towards the west coast Friday night, with
precipitation chances beginning early Saturday morning for the
northern portion of the area. Seasonal, or slightly below average
temperatures are expected through the period.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...

After looking at the 5H Cluster analysis for the weekend, confidence
is high that a long wave trof will dominate the wx pattern over
Norcal through much of the forecast period. Although there are
differences in timing and in the details a cooler and wetter
scenario is favored. A pair of Pacific storms will move through
interior NorCal, the first on Sat, followed by a colder/stronger low
Sunday. The deterministic ECM is slower than its counterpart on Sat,
then faster with the second system on Sun as the GFS slows down due
to the formation of a deep closed low off the CA coast.

Widespread precipitation is expected over Norcal this weekend with
Sun`s system bringing periods of moderate to heavy snow to the
Sierra/Wrn Plumas Co during the day and into the evening. Residual
showers are expected on Mon as the trof (ECM), closed low (GFS) pass
east/south of the CWA by the end of the day. Dry NWly flow aloft is
forecast on Tue with a chance of some upslope showers over the
Sierra in the afternoon.

A chilly/cold period is in store for Norcal with max temps some
10-15 degrees below normal on Sun, moderating to about a handful
of degrees below normal on Tue. JHM

&&

.AVIATION...

VFR conditions in the Vly with local MVFR conditions from 12z-18z
Wed. Over mtns, widespread MVFR and local IFR conditions with
scattered showers mainly N of I-80. Freezing level 6 kft over Nrn
mtns sloping to 7-8 kft over Central Sierra. Over mtns, local S-W
G50+ kts, and after 18z in Sac Vly Local NW G25 kts.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$


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