Scientific Forecaster Discussion
fxus66 ksgx 082130
Area forecast discussion
National Weather Service San Diego California
130 PM PST Thu Dec 8 2016
seasonal weather through Friday with scattered high clouds at times.
There will be some increase in low clouds west of the mountains this
weekend along with a small chance of light showers early Sunday.
Mostly sunny and mild early next week with weak high pressure aloft.
Late next week a trough will bring cooling and a chance for showers
Thursday or Friday.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Quiet weather over socal today with mostly sunny skies and
temperatures about where they should be for early December. The
storm track and will remain well to our north tomorrow, then briefly
dip south Saturday and Sunday before lifting north again early next
week. The southerly shift of the jet stream will bring stronger
onshore flow and increasing low level moisture for possible showers
Saturday night and Sunday. Precipitable waters increase from 0.85" today to 1.40"
Saturday night, onshore flow will be stronger, and the marine layer
will be deeper. But there really isn't a strong shortwave aloft to
enhance lift, so most of whatever precip that does fall will be
light with only trace amounts to a few hundredths of an inch west of
the mountains. Orographic enhancement will favor locally higher
amounts up to 0.10" on the coastal foothills and Lower Mountain
slopes. Other impacts will be stronger winds in the mountains and
high deserts over the weekend.
Long range outlook for next week: the 12z GFS and European model (ecmwf) show zonal
flow through the middle of next week with embedded shortwaves
bringing precipitation to the northern half of the state. Late next
week a significant pattern change is forecast with a transition from
zonal flow to a highly amplified long wave pattern across the lower
48. A longwave trough deepening along the West Coast Thursday will
bring a chance for precipitation as it moves across socal Thursday
night and Friday.
Late next week a deep polar low settles over central Canada which
will bring a blast of frigid Arctic air to the plains and the
intermountain west. Modified cold air from this pattern could filter
all the way into the southwest December 17-19. If so, it would bring
cooler than average weather along with cold overnight lows near
freezing that may impact the agricultural community.
082100z...coast/valleys...few/sct mid and high clouds through
tonight. Stratus, with bases 1000-1500 ft mean sea level and tops near 2000 ft
msl, will develop along the coast late tonight and into the coastal
valleys by early Fri morning. Areas of vis 2-4 sm br is expected
over higher coastal terrain through the period. Conditions will
improve by late Fri morning. Forecaster confidence is moderate.
Mountains/deserts... scattered/broken low clouds over the highest peaks of
the San Bernardino County mountains this afternoon. Variable high
clouds at or above 10000 ft mean sea level through tonight. Otherwise mostly clear with
unrestricted visible through Fri afternoon.
no hazardous marine weather is expected through Tuesday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.