Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
842 am PST sun Feb 14 2016
strong high pressure is building over the southwest once again and
developing offshore flow will result in Santa Ana conditions
through Tuesday with gusty winds near the coastal foothills and
unseasonably warm days. Cooler midweek as onshore flow returns
ahead of a low pressure trough moving inland along the West Coast.
The trough will bring a chance of showers by Thursday...and gusty
westerly winds over the mountains and deserts. Dry and warmer Friday
into next weekend.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Dense fog was persistent over northern Orange County as of 8 am
PST...but cleared the San Diego County coast early this morning. The
12z Miramar sounding had a strong surface-based inversion with light
and variable winds below 4k feet. Slight warming was indicated above
700 mbs. The surface pressure gradients showed neutral 24 hour
trends and were still about 7 mbs offshore from Nevada. As of 8 am PST...
winds were light across the region.
Sunny and mild today..then much warmer Monday and Tuesday under
building high pressure aloft and dry...offshore flow. Wind advisories
have been posted for this evening into Monday along and west of the
mts for gusty Santa Ana winds. Strongest below the Cajon Pass and
the Santa Ana mts.
From previous discussion...
For Wednesday night and Thursday...a trough of low pressure moving
inland along the West Coast will bring cooling to near average...
gusty west winds in the mountains and deserts...and a chance of
showers. There continue to be some run to run and model to model
differences with the trough timing and amplitude which would affect
the precipitation timing and amounts. The GFS has generally been a
little faster and weaker with the trough versus the European model (ecmwf) and
Canadian...but the 06z GFS was actually a little slower than the
European model (ecmwf) and more amplified than previous runs.
The GFS does continue to show a decent subtropical moisture plume
feeding into the system as it approaches from the west with
precipitable water values more than 200 percent of normal. Probability of precipitation
for Wednesday night and Thursday are still in the slight chance to
chance range...but could be raised for a portion of that time
period as the models converge on a solution.
Gradual warming for Friday and Saturday with greater warming for
Sunday and Monday as high pressure aloft strengthens near the West
141600z...clearing conditions along the immediate coast. However...
low clouds and fog may remain over portions of northwest Orange
County through around 14/1700z...before eroding to the beaches.
Mostly clear with unrestricted visible this afternoon through Monday
Valleys/mtns/deserts...mostly clear with unrestricted visible through
Monday morning. Local northeast winds with surface gusts to 30 knots
developing this afternoon...strengthening tonight into Monday
morning with gusts to 40 knots. Associated moderate uddfs and low level wind shear over/SW
of the mountains tonight through Monday...including vicinity kont and
Marine... 800 am...no hazardous marine weather is expected this
afternoon through Wednesday. A cold front will bring gusty southwest
to west winds and a chance of showers late Wednesday into Thursday.
Beaches... 800 am...the west-northwest swell from 290 degrees will
gradually lower today. Strong rip currents and high surf of 4 to 7
feet with sets to 8 feet will continue today. Highest surf will be
north of Newport Beach and south of del Mar. A high surf advisory
remains in effect through 8 PM this evening. The swell and surf will
continue to lower Monday.
offshore flow will strengthen into Monday with locally gusty
northeast winds developing near the coastal foothills. The winds will
strengthen and become more widespread later tonight into Monday...
weaken slightly Monday afternoon...then increase again Monday night
for a few hours. Strongest gusts are expected Monday morning.
Relative humidity will lower today with minimum daytime values
expected to remain in the 10-15 percent range through Tuesday.
The low humidity and gusty winds will bring several hours of near
critical fire weather conditions near the coastal foothills and below
passes and canyons for on Monday. Marginal fuel conditions are
expected to mitigate the potential for rapid fire growth.
Conditions will improve on Wednesday as onshore flow spreads higher
relative humidity inland and weaker winds prevail.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...Wind Advisory from 10 PM this evening to 2 PM PST Monday for
Riverside County mountains-San Diego County mountains-San
Diego County valleys.
Wind Advisory from 6 PM this evening to 2 PM PST Monday for
Orange County inland areas-San Bernardino County mountains-
San Bernardino and Riverside County valleys-the inland
Empire-San Gorgonio Pass near Banning-Santa Ana Mountains
High surf advisory until 8 PM PST this evening for Orange County
coastal areas-San Diego County coastal areas.