Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 272116

216 PM PDT Sat May 27 2017

A weak ridge aloft and shrinking marine layer will support a
warming trend through early next week. The ridge will be replaced
by a weak trough aloft by the middle of next week providing a
cooling trend with more widespread night to morning low clouds.



Satellite imagery showing mostly clear skies across the forecast
area this afternoon. Earlier this morning, ACARS sounding over
LA basin showed a marine layer depth around 3700 feet. A weakened
marine inversion along with offshore trends in the pressure
gradients allowed for low clouds to burn off this afternoon.
As a result, most areas seeing a 3 to 6 degree rise in
temperatures, except some mountain and desert locations where
temperatures have increased 10 to 20 degrees from this time

The marine layer is expected to shrink to around 1500 feet later
tonight into Sunday, as a weak offshore flow component develops
over the interior sections of the forecast area. This will result
in a further reduction of low cloud coverage for Sunday morning,
and lead to additional warming across the region. In fact, valley
areas are expected to climb well into the 80s on Sunday while the
Antelope Valley soars into the lower to mid 90s. Similar warm
temperatures expected on Monday. A weak upper level trough will
move into the area on Tuesday bringing an influx of higher level
clouds and a few degrees of cooling.


The GFS and ECMWF models in fairly good agreement on deepening
upper level trough for Wednesday across forecast area. This system
will likely bring a deepening of the marine layer while model
cross sections showing increased mid and high level clouds. Have
introduced a slight chance of showers for Wednesday afternoon
across north facing slopes and Antelope Valley. All portions of
the forecast area should see noticeable cooling on Wednesday. Weak
upper level ridge of high pressure will bring a slow warming
trend Thursday into Friday with little change into Saturday.



At 17Z, the marine inversion at KLAX was based at 3800 feet. The
top of the inversion was 6300 feet with a temperature of 14
degrees Celsius.

High confidence for VFR everywhere through 02Z...except for an
occasional BKN035 18-22Z at KLAX KSMO KLGB KBUR KVNY. Marine
layer and CIG should lower tonight into Sunday. 90 percent chance
of CIG at KSMX KLAX KSMO KLGB, 60 percent chance at KPRB KSBP KBUR
KVNY KOXR KCMA, 30 percent chance at KSBA. Possible CIG ranges of
010-015 KSMO KLAX KLGB. Moderate confidence in TAF timing +/- 3

KLAX...Occasional BKN035 possible through 22Z, low confidence on
timing. Typical seabreeze winds today. Light SE winds Sunday
morning under 6KT. Ceilings should return sometime between 06Z
and 10Z. 30 percent for a couple of hours just under 010, but
generally should be 010-015.

KBUR...Occasional BKN035 possible through 22Z, low confidence on
timing. Typical seabreeze winds today. 60 percent chance for
ceilings (006-010) Sunday morning arriving sometime between 09Z
and 14Z.


.MARINE...27/200 PM.

80 percent chance of low-end Small Craft Advisory (SCA)
conditions from the Central Coast to San Nicolas Island (Outer
Waters) late this afternoon...becoming certain by Sunday...after
which SCA conditions should persist at least through Wednesday.
Some of the winds will spill into the western half of the Santa
Barbara Channel each evening, but at this point does not look
expansive enough to warrant a SCA for the whole channel. These
winds will create a short period chop over all waters including
the Santa Barbara Channel and Santa Monica Basin (Inner Waters).
The winds peak Monday and Tuesday and there is a chance that Gale
Conditions form beyon 30 nm of the Central Coast.


PZ...Small Craft Advisory in effect from 3 PM to 9 PM PDT Sunday
      for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 AM PDT Monday for
      zones 670-673-676. (See LAXMWWLOX).


No significant hazards expected.



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