Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 250607
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1000 PM PST Sat Jan 24 2015

.Synopsis...
Dry weather with areas of night and morning valley low clouds and
fog through Monday. Temperatures expected to remain well above
normal through early next week in fog-free areas. Light
precipitation is possible Tuesday and Wednesday next week.

&&

.Discussion...
Stratus/fog reforming and expanding Nwd quickly over the CWA mainly
S of KMYV. Higher resolution models infer the ST/Fog will continue
to spread Nwd possibly as far N as KRBL Sun morning. The RDD-SAC
gradient has switched signs indicating the Nly flow is weakening
which makes the possibility of the ST spreading a little farther Nwd
than Sat morning.

As the upper high center shifts over Norcal on Sun...winds will be
lighter...making erosion of the cloud deck slower given the low sun
angle. While the ST/fog has been generally eroding from the N with
the aid of N winds during the last couple of days...the position of
the high center just to the NE of interior Norcal should cause some
erosion of the cloud deck from the E or NE...as well as from the
N...given the offshore trajectory of the wind. Thus...the ST/fog may
linger over the Wrn portions of the cloud deck...and in Solano
Co...longer than in other areas...generally speaking. This will have
an effect on Max Temps...and we have lowered the Max temps a little
from SAC and SUU Swd into the Nrn San Joaquin Vly in the evening
update. Lighter Nly flow also means less adiabatic warming effects
for the Nrn Sac Vly and a lesser chance of tying or breaking max
temps records compared to today. For now...the max temps look O.K.
up there.    JHM


.Previous Discussion...

The upper ridge shifts east of California on Monday, with some
synoptic cooling expected that day. We should also begin to see
increasing high cloud cover later on in the day as a system off
the Baja California coast moves northward.

Computer models are in better agreement on the track and timing of
this system. Looks like some precipitation will be possible along
the Sierra beginning Monday night and spreading northward on
Tuesday. Snow levels are currently expected to be around 6000-7000
feet, but only minor snow accumulations are expected. The valley
has lower odds of seeing precipitation, but can`t completely rule
out a sprinkle or light shower.

&&

.Extended Discussion (Wednesday through Saturday)

The weak low which is expected to develop off Baja California and
track through the Sierra should been mainly out of the area by early
Wednesday. There may be just a lingering light shower over the
Sierra crest with dry weather for the rest of the area. On Thursday
and Friday, a weak trough develops to the south and becomes an upper
low, with some moisture spreading into the Sierra south of I80. High
clouds will be the main affect for most of the area.

The upper low is forecast to slowly shift southward Saturday
and may spread a few very light showers northward up the Sierra
as far north as Tahoe. The rest of the forecast area will see
variable high cloudiness going into next weekend with daytime
highs remaining well above normal for the northern Sacramento
Valley under upper ridging. Temperatures further south expected
to be near to a little above normal. EK


&&

.Aviation...

Low clouds/fog and LIFR conditions tonight in the Srn Sac and Nrn
San Joaquin Vly...possibly expanding Nwd towards KRBL Sun morning.
Elsewhere...VFR. Light winds in foggy areas...otherwise north to
east winds 5 to 15 knots with gusts to 25 knots over
Sierra...decreasing on Sun.

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$








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