Scientific Forecaster Discussion
fxus66 klox 300340
Area forecast discussion
National Weather Service Los Angeles/Oxnard California
840 PM PDT Wed Mar 29 2017
a trough of low pressure will bring cooler conditions for
Thursday and Friday with another round of gusty northerly winds. A
brief warmup is likely this weekend with ridge of high pressure
nosing into the region, before another trough brings cooler and
breezy conditions early next week.
Mostly clear skies with a few hi clouds were noted across the
forecast area early this evening. There may be a few clouds
developing on the N mtn slopes later tonight, otherwise the mostly
clear skies will continue overnight. Gusty NW winds will persist
over the mtns and Antelope Vly thru the evening, with gusty N winds
across the sba County mtns and S coast below and thru the passes and
Upper level ridging over srn California this evening will weaken quickly
tonight while an upper level trof moves into nrn California. This upper
trof is forecast to be an inside slider and move inland to eastern
California and Nevada while deepening into an upper level low over Nevada on Thu.
The upper low will move se into Arizona Thu night and Fri, and E into New
Mexico Fri night and Sat. An upper level ridge will build off the California
coast Thu thru Fri, then begin to expand into California on Sat. A strong
northerly flow aloft and at lower levels will prevail Thu night into
Fri over swrn California.
Some cloudiness will be possible on the N mtn slopes on Thu,
otherwise mostly sunny to partly cloudy skies are expected across
the region. Gusty NW to N winds will begin to increase Thu
afternoon in response to the position of the inside slider and the
passage of a weakening cold front. Northerly gradients will increase
thru Thu evening, along with 850 mb winds (up to 55 kt) and 950 mb
winds (up to 30 kt). In addition, decent cold air advection will
prevail Thu night. These conditions will bring strong and gusty NW
to N winds to much of the mtns, Antelope Vly, and sba County S coast
Thu night into Fri morning. Wind gusts up to 80 mph will be possible
at the peak of the wind event Thu night over the l.A./Vtu County
mtns, up to 60 mph for the Antelope Vly Thu afternoon and evening,
and up to 65 mph Thu night for the sba County mtns, especially thru
the passes and canyons. There is also the chance for peak gusts up
to 60 mph in the Santa Monica mtns Thu night into Fri morning, but
the latest NAM forecast winds just below warning thresholds. High
wind watches have already been issued for these areas. Strong and
gusty N winds will likely also affect the Santa Clarita Vly,
portions of the vtu County vlys, San Fernando Vly, foothills of the
San Gabriel Vly, and l.A. County coast from Malibu to Hollywood
Hills, and possibly from Santa Monica to lax Thu night into Fri
morning. Wind advisories will likely be needed for these areas.
Gradients will turn more northeasterly Fri night, with a round of
gusty NE winds expected in the favored areas of vtu/l.A. Counties
Fri night into Sat morning, possibly to advisory levels in some
Needless to say, mostly clear skies are expected across the region
Thu night thru Sat thanks to the offshore flow. Temps will turn
quite a bit cooler Thu and Fri, but should still be near or slightly
above normal, with highs in the warmest vlys and inland coastal
areas reaching the mid 70s to near 80. Temps will warm to several
degrees above normal for most areas Sat with highs in the warmest
vlys and inland coastal areas reaching the upper 70s to mid 80s.
***From previous discussion***
Another pretty warm day Sunday, though likely a few degrees cooler
especially for coastal areas as offshore flow weakens. Models
continue to bounce around a little bit with the Monday trough.
Though virtually all solutions now are dry, the big question
remains how far south the trough will dig and whether we'll see
another burst of strong north winds late Monday into Tuesday.
Either way we should see another few degrees of cooling Monday,
then warming Tuesday/Wednesday as a ridge of high pressure
develops along the West Coast and gradients turn weakly offshore.
At 2255z, the inversion at klax was 100 ft deep. The top of the
inversion was at 1200 ft with a temperature of 22 deg c.
Generally hi confidence in the 00z tafs. VFR conditions are expected
at all the airfields thru Thu, except there should be a period of
IFR/MVFR vsbys at kpmd and kwjf aft about 21z Thu due to blowing
dust. There is, however, the slight chance (20 percent) of low
clouds with IFR cigs developing around klax and klgb aft about 12z
thru mid morning Thu. Gusty NW winds will affect ksbp and ksmx Thu
afternoon, with gusty W winds at koxr, kcma and klax, and gusty N
winds at kvny. Very strong W winds can be expected at kpmd and kwjf
late Thu morning thru the afternoon, with gusts up to 50 knots
expected, contributing to the reduced vsbys in blowing dust.
Klax...generally hi confidence in the 00z taf. VFR conditions are
expected thru Thu evening. However, there is the slight chance (20
percent) of low clouds with IFR cigs developing aft about 12z thru
mid morning Thu.
Kbur...hi confidence in the 00z taf with VFR conditions expected
thru Thu afternoon.
Across the outer waters...a combination of winds and seas will
keep Small Craft Advisory conditions through at least Thursday
morning. Gale force winds are likely Thursday afternoon through
Across the inner waters...strong Small Craft Advisory winds will affect the
western portions of the inner waters on Thursday and Friday with a
40 percent chc of gale force winds.
California...high wind watch in effect from Thursday evening through
Friday morning for zone 46. (See laxnpwlox).
High wind watch in effect from Thursday afternoon through
Friday morning for zones 52>54. (See laxnpwlox).
High wind watch in effect from Thursday afternoon through
late Thursday night for zone 59. (See laxnpwlox).
Pz...Small Craft Advisory in effect until 3 PM PDT Friday for zone
645. (See laxmwwlox).
Small Craft Advisory in effect until 1 PM PDT Thursday for
zones 670-673-676. (See laxmwwlox).
Gale watch in effect from Thursday afternoon through Friday
afternoon for zones 670-673-676. (See laxmwwlox).
Hazard potential outlook...(sat-wed)
gusty northeast winds are possible Saturday across la/Ventura