000
FXUS66 KSTO 221348
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
648 AM PDT Fri Mar 22 2019


.SYNOPSIS...
Another round of rain and snow this afternoon through Saturday
with enough mountain snow to impact weekend travel. Dry Sunday
then more rain and mountain snow Monday through most of next
week. Heaviest precipitation mid week.
&&

.DISCUSSION...
Clear skies over the forecast area this morning under small scale
upper level ridging. Satellite imagery shows a Pacific frontal
system approaching the coast at this time with warm frontal cloud
cover and light showers approaching the coast. Cloud cover should
begin spreading over the forecast area through the morning hours
with some light precipitation entering the western CWA by mid day.
Models indicating main frontal band will push into the western CWA
by this afternoon and then into the Sierra overnight.
Precipitation at the lower elevations is expected to be fairly
light with this system but good orographics will bring heavier
amounts over the Sierra Cascade range. Associated upper trough
moves across Norcal on Saturday for continued shower activity. Should
see enough snowfall below pass levels from mid day today through
mid day Saturday to justify winter weather advisory currently in
place. Stability proggs indicating some minor instability moving
across the north state Saturday afternoon as the trough axis moves
through. Have kept thunderstorm threat for the Sacramento valley
in the forecast even though the threat will be short lived with
trough axis expected to be along the CA/NV border by 00z Sunday. Cloud
cover and cooler air associated with this system will bring
daytime highs back down below normal both today and Saturday.

Skies clear out Saturday night with a fair dry day expected
Sunday as another shortwave ridge slides across the state.
Daytime highs Sunday should push back up to around normal. Next
round of precipitation pushes quickly into Norcal Sunday night
with the main frontal band pushing through the north state on
Monday. This system appears will be a little wetter than the
Today/Saturday system. Once again orographics will aid in
precipitation production so travel impacts over the Sierra will
again be likely.

&&


.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Showery precipitation continues on Tuesday with moist southwest
flow. Light snow accumulations are possible in the mountains.
There is some potential for afternoon convection in the Valley,
but confidence isn`t high enough to add mention of thunderstorms to
the forecast yet.

A stronger Pacific storm arrives Late Tuesday with more
widespread rain and mountain snow. The core of the storm moves
inland Wednesday and continues precipitation into Thursday.
Precipitation amounts for Tuesday through Thursday currently are
projected to be around 1 inch for the Central Valley and 2 inches
for the foothills and mountains. Mountain travel impacts due to
periods of heavy snow and strong wind are likely. Early estimates
of snow amounts are 1 to 2 feet above 5000 feet, potentially more
above 6000 feet. Friday looks drier with northwest flow, with just
some lingering light mountain showers. EK

&&

.AVIATION...

VFR conditions through 16z, becoming widespread MVFR with -RA
spreading across TAF sites by around 18z and continuing into
Saturday morning. Surface winds generally below 12 kt through 18z,
increasing to 12 to 15 kt over the northern Sacramento Valley,
with gusts to 20-25 kt. EK


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 11 AM this morning to 5 PM PDT
Saturday for West Slope Northern Sierra Nevada-Western Plumas
County/Lassen Park.

&&

$$