FXUS66 KLOX 291032

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
332 AM PDT Fri May 29 2020

.SYNOPSIS...29/243 AM.

Temperatures will cool today through Saturday and will be near
normal by Saturday. Overnight and morning low clouds and fog will
develop through at least Tuesday along the coast and at times
into coastal adjacent valleys. The Central Coast has a chance of
showers late Friday night and Saturday.


.SHORT TERM (TDY-SUN)...29/304 AM.

Strong onshore flow and increasing cyclonic flow aloft have
combined to bring low clouds and some fog to all of the coasts and
vlys as well as the coastal slopes. The onshore flow to the east will
peak this afternoon near 9 MB while the push to the north will
max out at 7 MB and this kind of onshore flow almost guarantees
no coastal clearing as well as slow vly clearing. Areas absent of
low clouds will be partly cloudy as mid level clouds stream
overhead from an approaching low. The clouds and the massive
onshore push as well as lowering hgts will drop max temps 4 to 8
degrees across the coasts and vlys, except for the Central Coast
which had their big cool down ydy, and 10 to 20 degrees across the

The upper low will make its approach to the Central Coast
tonight. A slight chc of showers will develop north of Morro Bay
this evening and then a chance of rain will overspread most of SLO
county after midnight. The unstable core of the low will make its
closest approach to the area after midnight and it will bring a
slight chc of TSTMs to the western half of the outer waters north
of Pt Conception. Elsewhere a deep marine layer will bring stratus
to all the coasts and vlys as well as the coastal slopes while
mid level clouds drift overhead.

A vort max will zip through SLO and SBA counties Saturday morning.
Rain is likely for NW SLO county while the rest of the Central
Coast will see a chc of rain. The eastern portions of SLO and SBA
county will have a slight chc of rain from this as well. Rainfall
amounts will generally be a tenth of an inch of less but areas
north of Morro Bay could see a quarter inch of rain. there will be
better clearing in the afternoon as the pressure grads relax and
the upper low clears out to the north. Hgts will fall to 578 DM
over LA county and 572 DM over SLO county. These lower hgts will
bring another 5 to 10 degrees of cooling to the interior. The
coasts and vlys will only cool a little or not at all.

Sunday will be a fairly unremarkable day with dry SW flow aloft.
Onshore flow will bring low clouds and fog the coasts and some of
the vlys. The onshore push in the afternoon will be weaker than
today and this will allow for total clearing. Max temps will climb
4 to 8 degrees due to the rising hgts, weaker seabreeze and
increased sunshine.

.LONG TERM (MON-THU)...29/324 AM.

The EC and GFS are coming into better agreement but still exhibit
significant differences. The ensembles are not that much help
with both ensemble clusters sticking fairly close to their
respective operational runs.

Both mdls now agree that an upper low will form to the SW of LA on
Monday. Neither mdl moves the upper low very much but the GFS
positions the low a couple hundred miles closer to the coast than
the EC. As a result the GFS is much wetter than the EC. The EC has
a stronger sfc reflection of the upper low and forecasts much less
onshore flow and even some offshore flow for SoCal.

Have generally discounted most of the wet GFS soln xcp for
Wednesday afternoon when a statistical mash up of most every long
range forecast indicates a slight chc of some showers over the LA
mtns and Antelope Vly.

Figure the onshore flow will come in somewhere in between the EC
and GFS and given the time of year and sea sfc temps think a
persistent night through morning low cloud pattern for the coasts
is the way to go. Its likely the the upper low will throw off
enough mid and high clouds to call skies partly cloudy through the

Max temps will be pretty close to normal through the period. They
will be a little cooler than fcst if the GFS is more correct and
conversely a little warmer if the EC forecast comes true.



At 0530Z at KLAX, the marine layer was around 1400 feet deep. The
top of the inversion was near 5000 feet with a temperature of 24
degrees Celsius.

Moderate confidence in the current forecast. Higher confidence in
timing, less confidence in the flight categories. IFR conditions
should improve to the MVFR category between 14Z and 16Z. There is
a chance of LIFR conditions from KSBA northward between 10Z and
14Z. Most coastal and valley terminals should remain shrouded in
MVFR conditions through today, then conditions will lower to the
IFR category between 01Z and 04Z.

KLAX...IFR conditions should improve to the MVFR category between
14Z and 16Z. MVFR conditions will likely linger through the
remainder of the period, but there is a 30 percent chance of brief
scattering out to VFR conditions between 21Z and 01Z.

KBUR...IFR conditions should improve to the MVFR category between
14Z and 16Z. MVFR conditions will likely linger through the
remainder of the period, but there is a 40 percent chance of
VFR conditions between 20Z and 04Z.


.MARINE...29/246 AM.

High confidence that winds and seas will remain below Small Craft
Advisory (SCA) levels through tonight, then moderate confidence
thereafter. There is a 50 percent chance of SCA level winds across
the north and west of the Channel Islands, then increasing to
50-60 percent Sunday through Tuesday. SCA level winds may also
spread into the nearshore waters north of Point Sal at times
through Tuesday.

Local SCA level winds could develop at times inside the southern
California bight during the afternoon and evening hours through
Sunday evening, especially through the Santa Barbara and San
Pedro Channels and near Point Dume.

Patchy dense fog with visibility one nautical mile or less is
possible at times across the waters through Friday morning.
Mariners should be prepared to reduce speeds and use GPS
navigation if available.


CA...Wind Advisory in effect from 3 PM this afternoon to 9 PM PDT
this evening for zone 37. (See LAXNPWLOX).
Beach Hazards Statement in effect from noon PDT today through
Sunday afternoon for zones 40-41-87. (See LAXCFWLOX).
Wind Advisory in effect from noon today to 9 PM PDT this
evening for zone 59. (See LAXNPWLOX).



No significant hazards expected.




Back to Main Forecast Discussion Page