Scientific Forecaster Discussion
fxus66 klox 241154
Area forecast discussion
National Weather Service Los Angeles/Oxnard California
454 am PDT Mon Apr 24 2017
an upper trough moving through the Pacific northwest will bring
cooler weather to the region today with gusty northwest to north
winds in some areas. Persistently sharp north to south pressure
gradients will keep breezy to locally windy conditions across
much of the region through at least Thursday. Temperatures will
generally be above normal in most areas Tuesday through Friday,
then well above normal over the weekend.
An eddy circulation across the inner waters has caused the marine
layer to deepen to over 1500 feet, and an organized area of low
clouds has overspread coastal sections of l.A. County and the San
Gabriel valley. Clouds were beginning to spill into the San
Fernando Valley, and may spread into vtu County from the east by
daybreak. Low clouds have also developed on the central coast and
in the Santa Ynez Valley. Otherwise, there was a fair amount of
high cloudiness drifting across the region this morning. Expect
low clouds to break up by late morning or around noon, then it
should be partly cloudy across the region. Max temps should be
down a few more degrees in most areas, down to near normal levels
in most areas.
Main story will be the winds. Good N-S low level gradients, and
decent upper support with good NW winds at 850 mb and subsidence
should continue to bring advisory level winds to the Interstate-5
corridor, southern Santa Barbara County through and below passes
and canyons, and the Antelope Valley today and tonight. Expect
advisory level northwest winds to develop on the central coast
this afternoon and evening.
An upper low will drop southeastward through the pac northwest today and
tonight, then into Utah on Tuesday. Models show some decent
upslope moisture from the northerly flow pushing into the
north facing mountain slopes tonight and Tue morning, and there
will be plenty of clouds and even a slight chance of showers.
Low cloud forecast for tonight and Tue morning is difficult. The
WRF shows low level nly flow wiping out the clouds in coastal
and valley areas south of pt Conception, with stratus developing
late tonight and early Tue on the central coast as low level
northerly flow pushes against the northern slopes of the Santa
Good northwesterly flow aloft and decent N-S low level gradients
should bring continue gusty northwest to north winds to the same
areas tonight through Tuesday night, so advisories in place
through late Tue night look good. Wind advisories will likely
be needed for the central coast Tue afternoon, and possibly for
coastal sections of l.A. And vtu counties. Slight rises in
heights and thicknesses and less in the way of low clouds should
lead to a couple of degrees of warming on Tue, especially in
coastal and valley areas.
Looks like less in the way of low clouds Tue night/Wed. Max temps
should rise a few more degrees in most areas on Wed as thicknesses
and heights cont to rise.
An upper low will drop into Idaho and Montana Wed night and Thu,
then into Utah on Fri. This will cause northwesterly flow aloft
to increase across the region Thu and Fri, and with continued
sharp N-S gradients, expect gusty northwest to north winds to
continue at times through Fri. Low level moisture on northern
mountain slopes could cause a few showers again late Wed night/Thu
morning, but have held off pops for now. There will be a few
degrees in most areas Thu, with additional cooling across the mtns
and Antelope Valley on Fri.
Height and thicknesses will rise over the weekend as an upper
ridge amplifies along the West Coast. Low level flow will
turn more northeasterly by Sat, and remain offshore, though weakly
on Sunday. Max temps should jump Sat, especially west of the
mountains, with well above normal temps expected in most coastal
and valley areas next weekend.
At 11z, the marine inversion at klax was based at 2100 feet. The
top of the inversion was around 3000 feet with a temp of 15c.
Expect MVFR conds across la County coast and valleys to the
coastal slopes. Also some MVFR stratus was developing around Santa
Ynez Valley and there is a 50% chance for MVFR stratus across
portions of the central coast through 16z. Also 50% chance for
some patchy MVFR stratus across Ventura coast and valleys after
13z to 18z this morning.
There will be areas of gusty NW winds through the pd across the i5
corridor, southern sba County, the Antelope Valley and on the
central coast. Expect some low level wind shear and MDT uddf through and below
passes and canyons, especially near ksba.
Klax...high confidence in the 12z taf through 17z with MVFR cigs.
There is a 30-40% chance that conds will persist into early this
afternoon. Gusty northerly winds should keep any stratus from
developing this evening into Tue morning.
Kbur...moderate confidence in 12z taf with MVFR conds thru 16-17z
this morning. Then VFR conds through Tue morning.
For the outer waters, high confidence in current forecast. Strong
northwest winds are anticipated to continue through the week.
Currently, a Gale Warning is in effect through late Tuesday night.
60-70% chance that gale force winds will likely continue through
For the inner waters, moderate to high confidence in current
forecast. For the waters north of Point Sal, strong Small Craft
Advisory (sca) level winds are expected each afternoon/evening
through Friday with a 30% chance of gale force winds developing
Tuesday through Friday. For the waters south of Point Conception,
Small Craft Advisory level winds are expected each afternoon and evening through
Friday with the strongest winds across the western Santa Barbara
Channel. Expect local gusts to 35 knots across the western
portions of the inner waters. For now have kept in strong Small Craft Advisory for
the inner waters. But there is a 60% for local gusts to 35 kt late
this afternoon through late this evening. And once again Tuesday
afternoon into the late evening hours. There will continue to be
a 50% chance of gale force winds across the far western portion
Tuesday through Friday across western sections. A 30% for
widespread gale winds for the same time frame.
Due to strong winds throughout the waters, seas will be very
choppy this week, making for hazardous boating conditions through
California...high surf advisory in effect until 10 PM PDT this evening for
zones 34-35-40-41-87. (See laxcfwlox).
Wind Advisory in effect until 3 am PDT Tuesday for zones
34-35. (See laxnpwlox).
Wind Advisory in effect until 3 am PDT Wednesday for zones
39-52>54-59. (See laxnpwlox).
Pz...Small Craft Advisory in effect until 3 am PDT Wednesday for
zone 645. (See laxmwwlox).
Small Craft Advisory in effect from 1 PM this afternoon to 3
am PDT Wednesday for zones 650-655. (See laxmwwlox).
Gale Warning in effect until 3 am PDT Wednesday for zones
670-673-676. (See laxmwwlox).
Hazard potential outlook...(wed-sun)
very gusty north to northwest winds are expected across southern
Santa Barbara County, the central coast, the I-5 corridor, and
the Antelope Valley. Advisory level winds expected at times and
possibly exceeding warning levels, especially in the I-5 corridor
and southern sb County Wednesday through early Friday.