Weather Service Report

FXUS66 KSGX 092133

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PST Fri Dec 9 2016

A weak trough passing by to the north will bring high clouds, a
deeper marine layer and possible light showers Saturday night and
Sunday. Weak high pressure aloft will bring seasonal weather Monday
and Tuesday. A stronger storm that could bring showers late next



Weak impulses in the fast zonal flow over the Pacific will bring
precip to NorCal this weekend, and perhaps a little light rain to
SoCal too. An atmospheric river over the Pacific currently aimed at
north-central CA will shift southward Saturday afternoon with a weak
shortwave. PWATS of 1.40" approach SoCal Saturday night, with most
of this increase in the 700-500 mb layer. This increased moisture
may contribute to scattered light showers in the mountains Saturday
night into Sunday. In the low levels, the marine layer will deepen
to 5000-6000 feet for possible light showers west of the mountains
Saturday night through midday Sunday. Weak PVA and the lack of a
strong lifting mechanism (sfc cold front) will limit the precip
potential with this system. Precip in most areas will be light with
trace amounts to a few hundredths of an inch, with locally higher
amounts of 0.10-0.20". The precipitation will end Sunday afternoon
as drier air moves behind the departing wave. Mild Monday and
Tuesday with scattered to broken high clouds in prevailing zonal
flow aloft. 

Long Range...Timing issues abound in the long range guidance next
week as zonal flow transitions into a high amplitude wave pattern
where predictability is lower. Guidance diverges early next week
with the ECMWF maintaining weak ridging over the Southwest, while
the GFS sweeps another trough across CA. Both models project a long
wave trough over the West late next week but with significant
timing, strength and location differences. Best solution today is a
model blend of the GFS and EC ensembles, both of which have
troughing over the Southwest late next week for cooler weather and
a chance of precipiation. 


092056Z...Coast/Valleys...Through 10/0000 UTC...FEW-SCT clouds 1500-
2500 ft msl (with local BKN clouds) and BKN clouds AOA 20000 ft msl.
Mostly vis P6SM expected through the afternoon. 10/0000-1500
UTC...OVC-BKN stratus quickly developing and filling the coast and
valleys with bases 1000-2000 ft msl, tops around 2500 ft msl, and
areas of vis 3-5 sm in the valleys. Forecast confidence is moderate. 

Mountains/Deserts...Unrestricted vis and BKN clouds AOA 20000 ft msl
continuing through Saturday morning. 


No hazardous marine weather is expected through Wednesday.


Although morning high tides will reach 6.7-7 feet Monday through
Thursday, surf and swells are expected to be small, so any tidal
overflow threat will likely be very localized and very minor. 


Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.






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