Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 280612
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1012 PM PST Mon Feb 27 2017
A trough of low pressure over the region will slowly move east
through Tuesday. High pressure will gradually establish between
Wednesday and Thursday and bring a warming and drying trend in
offshore flow through Friday. Offshore flow will linger into
Friday before being replaced by onshore flow for the upcoming
A plume of subtropical moisture focusesd heavy rains and flooding
concerns across San Diego County today, and continues this
evening. The northern edge of this moisture plume brought some
light shower activity earlier today to southern and eastern
portions of Los Angeles county, with a slight chance of showers
continuing this evening. Meanwhile, a cold but weak upper trough
has generated some isolated rain/snow showers across other
interior portions of the forecast area today, and this should
continue tonight. North facing slopes, including the Grapevine
area could see some light snow showers tonight, with accumulations
up to 1 inch possible. Snow levels are ranging between 3500 and
As the upper level trough moves through the region and passes
to our east, look for increasing northwest winds across the
mountains. The strongest winds will be focused across the
Interstate 5 corridor overnight into Tuesday morning, where
gusts of 45 mph can be expected. As a result, a wind advisory
was posted until noon Tuesday in the evening update. The
threat of showers should diminish for north facing slopes
after sunrise on Tuesday, with a general drying trend
across the entire region. Slight warming expected on Tuesday
with more significant warming and drying on Wednesday
as the flow turns offshore.
High pressure continues Friday though with weaker offshore flow.
Friday will be the warmest day of the next 7.
Both the EC and GFS agree that Saturday will be dry and also cooler
than Friday as the ridge is flattened out and the offshore flow
Trof or a ridge Sunday? You choose. GFS advertises a cool trof
while the EC forecasts a very large scale ridge. Will sit back and
take a wait and see approach to this forecast. Whatever the mdl it
will be dry.
At 06Z, there was a deep moist layer with no inversion to speak of
VFR conditions with occasional ceilings at or below 5000 feet
will improve through 12Z. 30% chance for weak to locally moderate
UDDF possible for KVNY, KBUR,KLAX, KSMO 09z-18z.
KLAX...Ceilings at or below 5000 feet will improve through 12Z.
There is a 30 % chance of weak UDDF and LLWS Northerly cross
winds should develop between 10Z and 16Z, possibly increasing to
between 10 and 15 knots between 10Z and 17Z.
KBUR...Ceilings at or below 6000 feet will improve through 12Z.
There is a 30 percent chance of weak to locally moderate UDDF and
LLWS between 10Z and 17Z.
For the Outer Waters, high confidence in current forecast. Winds
will increase to Small Craft Advisory (SCA) levels this afternoon
then continue at SCA levels through Saturday (although there may
be a bit of a lull during the day on Wednesday). Seas will
remain below SCA levels through Saturday.
For the Inner Waters, moderate confidence in current forecast.
Through Saturday, winds and and seas are expected to remain below
SCA levels. However, there is a 30% chance of SCA level wind
gusts this afternoon through Wednesday for the waters north of
Point Sal. For the waters south of Point Conception, there is a
20% chance of SCA level gusts tonight through Tuesday evening.
CA...Wind Advisory in effect until noon PST Tuesday for zones
53-54. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Tuesday for
zones 645-650-655. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PST Wednesday for
zones 670-673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(THU-MON)
On Thursday, offshore winds could be gusty across Los Angeles and
Ventura Conuties and create hazards for motorists, especially for
those operating high-profile vehicles.