000
FXUS66 KSTO 211034
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
334 AM PDT Thu Mar 21 2019


.SYNOPSIS...
Scattered mountain showers today with light snow higher
elevations. Another round of rain and snow Friday afternoon
through Saturday with enough mountain snow for travel impacts.
Dry Sunday then more rain and mountain snow early next week.
&&

.DISCUSSION...
Negative tilt upper trough over the state this morning brought a
few light showers to the northern Sacramento valley earlier this
evening as well as some light shower activity over the northern
Sierra. Most showers have ended but a slight threat of mountain
showers will continue today as the upper low shifts eastward into
the the Great Basin. Daytime highs will reach near normal today in
the central valley under mainly sunny skies while the mountains
remain mostly cloudy. Most areas will see dry conditions tonight
under brief upper level ridging before the next Pacific frontal
system pushes onshore Friday morning. By mid day Friday, areas
west of the Sacramento valley should be seeing light precipitation
if current model projections hold. By Friday afternoon, the
frontal band shifts inland over Norcal with precipitation
expected over the Sierra Cascade range. Travel impacts are likely
over the Sierra during the Friday to Saturday afternoon timeframe
as the moderately cold for the season storm system will likely
bring several increases of snowfall below pass levels.  Have
therefore issued a winter weather advisory to deal with likely
travel difficulties. Light precipitation at the lower elevations
will likely only bring minimal issues. The main upper trough is
forecast to move through Saturday afternoon and night for
continued shower activity over the Sierra Cascade range. Snow
levels at this time are forecast to drop to 4000 feet before
precipitation drops off Saturday night.

Upper ridging will make Sunday a fairly dry day with mainly fair
skies warming daytime highs to near or a little above normal. This
dry period should make Sunday a fairly good travel day. This break
will be fairly brief, however, with the next Pacific system
pushing inland by Sunday night.

&&


.EXTENDED DISCUSSION (Monday THROUGH Thursday)

An unsettled and cool pattern is expected next week, with periods
of rain, mountain snow and breezy winds.

Confidence is good that wet weather will spread across the area
Monday, with general agreement across GEFS ensemble membersand the
potential for a weak atmospheric river continues. Models are
pretty consistent in directing the best moisture over Northern
California, but there is some variance in exactly where.

Additional waves with decent moisture plumes are expected to
continue through the week, bringing periods of moderate to heavy
rain, but exact timing remains uncertain. Early estimates of
precipitation are around 1 to 4 inches for Monday through
Wednesday. Snow levels continue to range between around 5000 to
6000 feet, with the potential for travel delays. EK

&&

.AVIATION...

VFR conditions are expected over the next 24 hours. Winds are
expected to generally under 10 knots. EK

&&

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

&&

$$