Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 252046
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
146 PM PDT THU AUG 25 2016
A low will bring a deeper overnight marine layer and cooling trend
into Saturday. Then early next week a high will reduce the cloud
coverage and start a warming trend. By midweek another low should
arrive for a deeper overnight coastal marine layer and a cooling
trend into the weeks end.
The approaching weak trough already having the expected impacts
locally, those being increased onshore flow, cooler temps, and
increased marine lyr coverage with later clearing times (including
the coastal valleys). We should see all these trends continuing
Friday with temps generally 1-3 degrees, though more like 4-8
degrees across inland SLO county with likely some marine lyr
developing in the southern Salinas Valley later tonight.
We`ll turn the corner over the weekend as the trough exits to the
east and is replaced by an even stronger high pressure ridge than
we had a couple days ago. Temps will nudge upward Saturday but
bigger jumps Sunday as the ridge builds.
The ridge will strengthen further Monday and peak early Tuesday.
Warmer valley highs expected to climb into the lower triple digits
(100-103). For coastal areas gradients do trend offshore but not
really enough to offset the marine lyr impacts. Still, inland
coastal areas should reach the mid to high 80s early next week.
The ridge starts weakening Tuesday, though initial cooling should
be confined to northern areas. For southern areas high Tuesday
shouldn`t be much different than Monday and possibly even a degree
or two warmer across the interior. Beyond Tuesday models differ
with respect to the pattern, with the GFS showing just a slight
cool down mid to late week then turning warmer again by next
weekend. The ECMWF shows a continued cooling trend through the
period. Have trended towards the warmer GFS solution as that seems
to have been the better performer lately.
At 16Z at KLAX... the inversion was around 1200 feet deep. The
top of the inversion was near 4500 feet with a temperature of
about 23 degrees Celsius.
Overall... Moderate to high confidence in the 18z TAFs. Marine
incursion is lingering again this morning. Not a surprise along
the Central Coast but strong lingering in the bight supports a
widespread marine push tonight across all coastal areas and a
strong incursion into the adjacent coastal valleys as well.
Lowering pressure should lift the inversion enough to keep the
visibility off the deck but there will be some locations with
vsbys dipping below three miles at times. Clearing will be slow
again tomorrow morning. Gusty winds in the Antelope Valley will
continue through late Friday. Smoke continues in northern San
Luis Obispo County from the Chimney Fire and in Santa Barbara and
western Ventura Counties from the Rey Fire. Otherwise and
elsewhere VFR conditions will prevail.
KLAX... Moderate to high confidence in the 18z TAF. Marine
incursion is lingering this morning which supports an early return
tonight. Lowering pressure should lift the inversion enough to
keep the visibility off the deck but there will be some reduction.
Clearing will be slow again tomorrow morning. Otherwise VFR
conditions will prevail.
KBUR... Moderate to high confidence in the 18z TAF. Marine
incursion is lingering this morning which supports a strong push
into KBUR tonight. Lowering pressure should lift the inversion
enough to keep the visibility off the deck but there may be some
reduction. Clearing will be slow tomorrow morning. Otherwise VFR
conditions will prevail.
Conditions will remain below advisory levels through Saturday.
Winds across the outer waters will strengthen late Saturday and
Small Craft Advisories may be needed for some areas by Sunday.
Patchy fog will be widespread across the coastal waters through
Saturday... most intense in the overnight and morning hours.