Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Los Angeles/Oxnard California
939 am PST Friday Feb 12 2016
A fast moving low will bring some clouds and cooler temperatures
on Saturday. The high will then rebuild...and offshore
winds and near record temperatures are expected early next
week. A low system will arrive by midweek for possible
precipitation and a cooling trend into the weeks end.
Latest satellite shows some scattered high clouds drifting
overhead with some patchy stratus along the central coast and
coastal waters. This stratus should dissipate quickly...and the
balance of the day will be mostly sunny/partly cloudy. There was
some dense fog earlier...but it has dissipated. Therefore the
dense fog advisory has been cancelled. Surface gradients are
currently trending slightly onshore. So...with the upper ridge
weakening a bit...the onshore trends should allow for a bit of
cooling across the coasts and valleys today.
Quick look at initial 12z model data indicates no major changes to
previous forecast thinking. Weak disturbance will move across the
area late tonight and Saturday...allowing for a bit more cooling
on Saturday...and the possibility of a little more stratus for the
coastal areas (although confidence in stratus forecast is low). On
Sunday...the upper level ridge builds back in from the west and
the offshore gradients strengthen. So...expect a nice warmup on
Sunday along with some locally gusty offshore winds in the usual
Overall...current forecast looks good in the immediate short term.
Did update the zones earlier to remove the dense fog headline. No
further updates are planned.
By Monday...a rather strong 589dm high sets up just off the
southern and central coast with a weak cutoff low just to the SW
of the high. At the surface...a relatively strong offshore
surface gradient sets up as a 1030mb high builds in over northern
Nevada. This will translate to warmer temperatures and a moderate Santa
Ana wind event. Lax-dag surface gradient was -6.8mb. Some upper support
over the mountains...but not much over coast and valleys. By
Tuesday the upper ridge axis will weaken but persist overhead
while another upper trough starts to dig south towards northern cal.
High temperatures will remain close to monday's for areas S of Point
Conception...but should see some minor cooling for areas to the
north. Expect highs for la/vtu coast and coastal valleys to be in
the middle to upper 80s...with cooler conds for areas to the north
and interior locations.
By Wednesday...a broad trough with a more significant cold front
will move into northern California...then slide south to bring
rain into the forecast area by Wednesday night or Thursday. With
the models consistent in the slow down of the approaching storm
have backed off probability of precipitation 6-12 hours. Looks like the brunt of the storm
will be Thursday into Thursday night...with possible residual
showers into Friday. Too early to get a handle of rainfall
amounts...but looks like the snow level will begin above 6500
feet...then lower to between 5500 and 6000 feet Thursday-Thursday
night. High temperatures will only reach the middle 70s Wednesday...with
even cooler conds on Thursday with the rain.
Upper level trough of low pressure upstream will shift southeast
while a middle level ridge of high pressure builds over the area. Upper
level moderate southwest winds will become moderate north by
14/00z while middle level light and variable winds become light
north-northwest after 12/17z. Mixed weak onshore and northerly
gradient through 13/02z then weak to moderate northerly gradient
between 13/03-13/20z and then mixed weak onshore and weak to
moderate northerly gradient.
Marine layer at lax at 1600z is none.
Klax...there is a chance visibility 5sm br between 13/12-12/17z
otherwise current sky/visibility conditions will likely exist.
Kbur...current sky/visibility conditions will very likely persist
through the period.
Virtually certain - 95-100%
very likely - 80-95%
likely - 60-80%
chance - 30-60%
very unlikely - 20% or less
Northwest winds will increase and Small Craft Advisory conditions
are likely from Piedras Blancas to Point Sal 10-60 nm and from
Point Sal to Santa Barbara Island each afternoon through Sunday.
Small Craft Advisory for hazardous sea conditions with swells
over 10 feet is likely from Piedras Blancas to San Clemente Island
excluding the inner basins south of Point Conception through
Sunday. There is a chance swells will build to near 10 feet in the
Santa Barbara basin tonight. Northeast winds will likely develop
from Ventura to Santa Monica Sunday morning and again early Monday
morning. The northeast will likely create Small Craft Advisory conditions Monday
morning and there is a low chance Sunday morning.
California...high surf advisory in effect until 9 am PST Sunday for zones
34-35. (See laxcfwlox).
Beach hazards statement in effect through Sunday morning for
zone 39. (See laxcfwlox).
High surf advisory in effect until noon PST Sunday for zones
40-41-87. (See laxcfwlox).
Pz...Small Craft Advisory for hazardous seas in effect until 9 PM
PST Sunday for zone 645. (See laxmwwlox).
Small Craft Advisory in effect until 3 am PST Monday for
zones 670-673-676. (See laxmwwlox).