Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
321 PM PST Mon Jan 26 2015
a weak storm system will bring light showers to norcal late
tonight and Tuesday. The best precip chances will be over the
High Sierra where 1-2 inches of snow will fall above 6000 feet.
upper low is spinning just west of San Diego. Moisture generally
at mid/high level is moving up from the south in advance of the
system. A few showers showing on radar south of Fresno. Showers
will spread north over the Sierra after midnight with isolated
showers possible for the valley towards morning into Tuesday.
Rainfall amounts will be light with opf's under 0.05 inches for
valleys and up to 0.25 for the mountains. Models have trended
drier with this system over the past few runs. Snow levels will
be above 6000 feet with 1-2 inches possible.
Another weak system will move through the area from the southwest
on Wednesday. Current models are not indicating any precip with
this system...only increased cloud cover. System will track east
into the Great Basin Thursday with high pressure building back
over the area. High temperatures will be upper 50's to upper 60's
through the period.
Extended discussion (friday through monday)
Upper level trough over the Desert Southwest on Friday. This will
bring a slight chance of precipitation near the Sierra
crest...mainly south of Highway 50 on Friday. High pressure
builds into northern California from the eastern Pacific on
Saturday and the low retrogrades over Southern California and
Mexico. This will bring dry weather on Saturday. North to east
winds are expected Friday into early Saturday as surface high
pressure builds into the Pacific northwest and into Nevada. Breezy
and gusty north to east winds are expected to weaken on Saturday
afternoon as the surface high shifts to the East.
Ridge flattens Sunday into Monday with the potential for some
disturbances moving through. The timing and track of these varies
with the models but they could bring a threat of precipitation and
have introduced slight shower chances for Shasta County and also
over all mountain areas Mon-tues.
Taf sites are currently at VFR conditions as low clouds have
either scattered out or lifted. Mid and high clouds spreading
northward ahead of low pressure system moving northeast into
California with potential showers Tue remaining over Eastern
Valley and mtns. Expect MVFR conditions to return late tonight for
most of the taf sites with local IFR/LIFR possible between
10-17z. Southerly winds will remain light bewteen 3-10 kts.