Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 082055

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
155 PM PDT Sat Aug 8 2020

.SYNOPSIS...08/117 PM.

Slightly warmer and near normal Sunday through Tuesday, then more
warming Wednesday through Saturday. Low clouds and fog will
persist over coastal sections, otherwise clear skies.


.SHORT TERM (TDY-TUE)...08/127 PM.

The very weak upper level low, currently spinning over northern
California, will get pushed to the west Sunday through Tuesday by
an upper level high expanding over northern Mexico. This will
bring some warming to the region tomorrow with very little change
through Tuesday. Temperatures should push back up to normal,
especially over the mountains and valleys where daytime
temperatures between 90 and 100 are expected in the warmest spots.
Coastal plains and nearest valleys will continue to be driven by
the ebbs and flows of the marine layer, which continues to be on a
frustratingly unpredictable bent. Still expecting temperatures to
generally be higher in these areas, but the trends will be more
of a mixed bag in space and time. Sunday should generally be the
warmest, when onshore flow is the weakest of the next few days and
the low clouds and fog should be the shallowest. There may even be
some dense fog with low visibility, especially on the Central
Coast. Gusty onshore winds will impact the interior valleys and
deserts each afternoon and evening, especially Monday and Tuesday,
but should stay under advisory and in the envelope of what is
typical for this time of the year.

.LONG TERM (WED-SAT)...08/152 PM.

Warming trend looking more likely starting Wednesday or Thursday
and lasting through at least Saturday, as the previously
mentioned high over northern Mexico steadily expands and
strengthens each day, while shifting northward into the four
corners. Projections still differ as to how much warming we can
expect however. The ECMWF and most of it ensembles remain very
bullish, with the core of the high expanding into southern
California and onshore gradients turning slightly offshore each
morning. The GFS and nearly all of its ensembles keep the core
from expanding out of Arizona, with similar but weaker trends in
the surface pressure pattern. While confidence is growing for
widespread above normal temperature and a shrinking marine layer,
to what degree is still very much an unanswered question. Prefer
to lean toward the more bullish ECMWF as it seems that the GFS is
trending toward it as opposed to the other way around. By leaning
the forecast in that way, starting to see more daytime
temperatures around 100 degrees in the warmer valleys and
mountains by Friday and Saturday. At this point, not expecting an
Heat Advisories, but there is a small chance in the event that
the ECMWF solution wins out. No appreciable threat of any
monsoonal surge through next week, but there is a window for the
following week, as well as a chance for even more warming.



At 1730Z at KLAX, the marine layer was 1300 feet deep. The top of
the inversion was around 3200 feet with a temperature of 20 C.

Moderate confidence in the 18Z TAFs at the coastal airfields. Low
clouds and LIFR/IFR/MVFR conditions should move into the airfields
from this evening at KSMX and KSBP to late tonight elsewhere. The
clouds should dissipate by 18Z Sun. There is uncertainty in the
timing and extent of the low clouds, with airfields S of Point
Conception possibly not having any low clouds or minimal low
clouds. The timing of the onset and dissipation of any low clouds
may be off +/- an hour or two. Otherwise, VFR conditions can be

For the valley and desert airfields, there is hi confidence in the
18Z TAFs with VFR conditions expected thru Sun morning.

KLAX...Moderate confidence in the 18Z TAF. Low clouds and
IFR/MVFR conditions are expected from 11Z-18Z Sun. There is
uncertainty in the timing and extent of the low clouds, with a
20%-30% chance the airfield may not have any low clouds or minimal
low clouds. The timing of the onset and dissipation of any low
clouds may be off +/- an hour or two. Otherwise, VFR conditions
can be expected thru Sun afternoon.

KBUR...Hi confidence in the 18Z TAF with VFR conditions expected
thru Sun morning.


.MARINE...08/1259 PM.

High confidence that winds and seas will remain below Small Craft
Advisory levels through Tuesday night across all waters. However,
there is a 30% chance of SCA level gusts over portions of the
coastal waters Wednesday and Thursday.





No significant hazards expected.



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