Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 202059

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
159 PM PDT Fri Apr 20 2018

.SYNOPSIS...20/1230 PM.

A high and offshore flow will bring above normal temperatures into
Monday for the inland areas. An eddy will usher in overnight coastal
low clouds and fog from Saturday into Monday. Then a low should
arrive by Tuesday for increasing onshore flow and a cooling trend
west of the mountains through Friday.


.SHORT TERM (TDY-MON)...20/146 PM.

Pretty quiet weather pattern next several days. A ridge of high
pressure will build tonight along the west coast and should shrink
the marine layer depth quite a bit. Profilers and soundings
already showing impressive warming aloft which confirms the
presence of the ridge. Gradients also turn lightly offshore Sat
morning. Probably not enough to keep low clouds away from at least
the coastal areas but enough to generate decent warming inland and
maybe a couple degrees at the coast.

Sunday and Monday look like pretty solid marine layer days at
least for coast and coastal valleys. The ridge weakens Saturday
night and a trough will pass north of the area Sunday. This will
deepen the marine layer and increase onshore flow through at least
early next week, bringing cooler temps inland but still near to
slightly above normal.

.LONG TERM (TUE-FRI)...20/158 PM.

Models seem to have settled down on a solution for next week,
keeping the upper low well west of the coast through at least the
middle of the week, then lifting it northeast into the Pac NW
Friday night into Saturday. This will keep some ridging along the
coast going through mid week at least, however onshore flow
strengthens slightly each day. So it looks like the marine layer
should be a consistent feature for coast and coastal valleys next
week with temps near to slightly above normal. A strong onshore
push will likely cool temps to below normal by the end of the week
with some gusty winds in the Antelope Valley.



At 17Z, the marine layer at KLAX was 1800 feet deep. The top of
the inversion was 3000 feet at 12 degrees Celsius.

High confidence in VFR conditions everywhere through 01Z with
seasonal onshore flow. 40% chance of IFR ceilings at KSMX 01-06Z,
likely clearing by 08Z. Ceiling possibilities after 06Z...80%
KSBP KPRB. Low confidence on ceiling heights, with anything
between 005-015 possible.

KLAX...High confidence in VFR through 06Z with seasonal onshore
flow. 80% chance of ceiling tonight with arrival window of 06-10Z.
If ceilings form, 60% chance of low-MVFR, 30% chance of IFR, 10%
chance of LIFR. SE winds will form again after 08Z, likely under
08 KT.

KBUR...High confidence in VFR through 09Z with seasonal southerly
winds. 20% chance of IFR conditions 10-16Z.


.MARINE...20/122 PM.

Low confidence on fog forecast, but dense fog is possible now
through the weekend. High confidence in widespread short period
seas into tonight, with decreasing heights.

High confidence in Small Craft Advisory (SCA) winds from the
Central Coast the San Nicolas Island through tonight, with weaker
and more borderline SCA over the weekend. Over the inner waters
from the Santa Barbara Channel to the San Pedro Channel, SE winds
will form each morning through at least morning, up to 15 kt
through the passages and channels. Typical onshore winds expected
in the afternoon, with near SCA west winds on the far western
Santa Barbara Channel.


PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 645-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Sunday for
      zones 670-673. (See LAXMWWLOX).



No significant hazards expected.



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