FXUS66 KLOX 192339
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
439 PM PDT Mon Aug 19 2019
Updated Aviation Section
Temperatures will warm into midweek with many locations in triple
digits Wednesday and Thursday. Temperatures will cool slightly
into the weekend. Overnight and morning low clouds and fog will
diminish in coverage each day through Thursday then increase
coverage again beginning Friday.
.SHORT TERM (TDY-THU)...19/151 PM.
The latest satellite imagery shows a ridge of high pressure over
the Texas Panhandle. This ridge will build into the Four Corners
Region through Tuesday while expanding westward into the area. 500
mb heights will climb and 1000-500 mb thickness values will
increase into Wednesday. Onshore flow will weaken and the marine
layer depth will thin over the coming. A warming trend will
develop across the area over the next couple days. Temperatures
will warm to above normal values on Tuesday then to well above
normal on Wednesday. The hottest temperatures will likely occur on
Wednesday when 500 mb heights and 1000-500 mb thickness peak
across the region. Dangerously hot conditions could develop for a
brief on Wednesday, but at this point, it seems a bit less likely
from the latest model solutions.
With the marine layer thinning, there is a good chance that dense
fog issues will develop each night and morning, especially near
the coast. The marine layer will thin substantially tonight and
into Tuesday morning to around 1000-1200 feet, then the marine
layer depth will thin to near 500-700 feet deep Tuesday night and
A tightening northerly gradient will increase winds across
southern Santa Barbara County and through the Interstate 5
Corridor each night. Sub-advisory Sundowner winds are expected
tonight with only local advisory level gusts. The best chance of
any wind advisory level Sundowner winds looks to be from late
Tuesday afternoon through early Wednesday morning, and Wednesday
afternoon through early Thursday morning. Farther east in the
Interstate 5 Corridor, breezy to locally windy conditions will
develop. Local advisory conditions could be met the next nights
and mornings near sites such as Whitaker Peak.
A trough of low pressure will brush the area to the north and
possibly bring some cooling for late this week. Onshore flow
should strengthen and the marine layer depth should deepen some.
.LONG TERM (FRI-MON)...19/219 PM.
The trough axis will likely move east of the area on Friday, then
ridging aloft should build back in for the weekend. Both ECMWF
and GFS model solutions agree that the region will sit between a
ridge centered to the west over the eastern Pacific Ocean and
another ridge centered east of the area over northern New Mexico.
Some warming should be expected for the upcoming weekend as
onshore flow will likely weaken and the marine layer will thin.
Model solutions continue to lean toward a tropical cyclone
developing off the Mexico Coast then drifting northwest along the
coast of Baja California. There is still uncertainty with this
solution, but ensembles are starting to fall inline with this
idea, leaning toward a wetter solution early next week. ECMWF
solutions are much more progressive with the feature, possibly
bringing the remnants north into the region between Sunday and
Monday, while GFS solutions are a bit slower. Ensembles are
starting to lean toward the ECMWF solutions. A dry forecast
remains for early next week, but PoPs may need to be added if
model trends continues.
At 23Z over KLAX, the marine layer was 1200 ft deep. The top of
the inversion was around 3100 ft with a temp of 24C.
The marine layer and associated CIGS should lower tonight compared
to last night. Moderate confidence in IFR conditions at KPRB KSBP
KSMX KOXR KSMO KLAX KLGB tonight. 20 percent chance of IFR
conditions at KCMA KBUR KVNY KSBA.
KLAX...80 percent chance of BKN008-10 conditions tonight, likely
forming by 06-10Z. 20 percent chance of brief BKN010 00-03Z. 20
percent chance of BKN004 11-15Z.
KBUR...VFR conditions like to prevail through Tuesday, except for
a 20 percent chance of IFR BKN005 11-15Z.
For the Outer Waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) level winds are expected
to develop this afternoon and continue through at least late Tue
night, and possibly through late Thu night. There is a 30% chance
of a period where winds drop below SCA levels late Tue night and
For the inner waters north of Pt Sal, only fair confidence in
forecast beyond today. No SCA level conds are expected today.
There is a 40-50% chance of SCA level winds during the afternoon
and evening hours Tue through Thu.
For the Inner Waters south of Point Conception, SCA level conds
are not expected through Fri. The exception is across western
portions of the SCA Channel, where there is a 20-30% chance of SCA
level NW winds this evening, and SCA level NW winds are expected
during the late afternoon through late night hours Tue and Wed,
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
zones 670-673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK (THU-MON).
Hot temperatures could lead to Heat Advisories for some inland
areas Thursday. The remnants of a tropical system could move north
into the region and bring chances for shower and thunderstorm
activity early next week. Strong rip currents and elevated surf is
also possible area area beaches.
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