Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 010912
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
212 AM PDT FRI JUL 1 2016
Strengthening onshore flow and a deepening marine layer will bring
a cooling trend into weekend. Marine layer clouds will reach into
the valleys, however warm and dry conditions will prevail in the
mountains and deserts. A gradual warmup is expected early next
week as high pressure builds in over the desert Southwest.
Overall, 00Z models in good synoptic agreement through the period.
At upper levels, weak trough will linger across California through
the weekend. Near the surface, moderate onshore flow will
Forecast-wise, the main concerns in the short term will be the
marine layer stratus and temperatures. With the upper trough
lingering and moderate onshore flow, the marine inversion should
deepen a bit from day-to-day. So, will expect stratus/fog to push
into the coastal valleys each night/morning. Each afternoon, the
stratus should dissipate nicely although some beach areas could
be slow to clear. Other than the marine layer stratus, skies
should remain clear as southwest flow aloft keeps any moisture to
As for temperatures, only minor changes are expected from day-
to-day. There will be some slight cooling today/Saturday then a
bit of warming on Sunday. Overall, temperatures for most areas
will likely be a couple of degrees below seasonal normals through
With the moderate onshore flow, there will be some gusty afternoon
and evening winds across the mountains and deserts. At this time,
winds look to remain below advisory levels although some isolated
areas (such as Lake Palmdale) could experience some gusts near
For the extended, 00Z models continue to exhibit decent synoptic
agreement. At upper levels, the area will be between a ridge over
the central states and a trough over the Pacific Northwest. Near
the surface, weak to moderate onshore flow looks to continue.
Forecast-wise, things will remain on the quiet side through the
period. Due to the upper level pattern, southwest flow will
prevail through the week which will keep any monsoonal moisture
well east of the state. So, the only clouds of note will continue
to be the marine layer stratus which should continue to push into
the coastal valleys each night/morning. As for temperatures, there
will be a gradual warming trend as thicknesses rise and the marine
influence decrease slightly each day.
At 00Z at KLAX... The inversion was about 1300 feet deep. The top
of the inversion was near 4300 feet with a temperature of about
27 degrees Celsius.
Overall...Moderate confidence with 00z tafs. S of Point
Conception...confidence is good with timing of marine layer
returning with higher IFR/low MVFR cigs beginning within +/- 1
hour of tafs. Similar timing for scouring out cigs along coastal
tafs Fri morning. 30 percent chance that cigs could linger an
additional 2 hours along coastal taf sites. N of Point Conception.
Higher confidence with mainly IFR cigs but could see brief moments
of MVFR cigs by 15-17z Fri before scouring out. 30 percent chance
that cigs could linger a few more hours than tafs represent along
KLAX... Moderate confidence in the 00z TAF.
Confidence is a bit shaky with the timing that IFR/MVFR cigs will
move in this evening. But should be within a couple hours of taf.
Also, similar situation for scouring out times in the late morning.
There is a 30 percent chance that cigs could linger a few hours
longer than 00z taf shows.
KBUR... Moderate confidence in the 00z TAF. The uncertainty is
due to the timing and if the cigs will make it to KBUR. But
chances are better tonight as the marine layer should deepen. The
deeper marine layer stratus will also result in a slightly
delayed scour out time tomorrow morning but KBUR will be VFR by
Overall... Small Craft Advisory winds will continue across the
outer waters through the overnight hours tonight. Steep combined
seas of 7 to 10 feet across the outer waters will slowly subside
tonight as well. Winds and seas across all coastal waters will
remain below advisory levels from Friday morning through the
Patchy dense fog will continue across the coastal waters into at
least the weekend.
Elevated fire danger will continue across the mountains, deserts,
and interior valleys through the weekend due to combination of
gusty onshore winds, warm temperatures, and low humidities.
The Pines Fire which is burning in the mountains of Ventura
county will be vulnerable to minimum humidities each day
between 10 and 15 percent, possibly reaching single digits
over the weekend. In addition, there will be poor humidity
recoveries at night. Gusty onshore winds will impact the
fire area each afternoon. There is the potential for
vertical smoke plume growth once again during the afternoon hours
on Friday due to ample daytime heating and instability in the
atmosphere combined with the very dry fuels.
Meanwhile, gusty onshore winds of 25 to 40 mph will be common
across the mountains, Antelope Valley, and interior valleys
during the afternoon and evening hours through the weekend.
Isolated gusts as high as 50 mph can be expected in the foothills
of the Antelope Valley near Lake Palmdale. Datyime humidites in
the single digits and teens can be expected in the mountains and
Antelope Valley, bringing the potential for brief critical fire
weather conditions each day.
CA...Beach Hazards Statement in effect through this evening For
zones 40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT early this
morning For zones 670-673-676. (See LAXMWWLOX).