Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Los Angeles/Oxnard California
903 PM PDT Thursday Jul 28 2016
High pressure aloft will result in above normal temperatures
through the end of the week, with night through morning low clouds
and fog affecting some coastal areas. Monsoonal moisture will
bring a slight chance of thunderstorms for the mountains and
desert for the weekend and early next week. Temperatures will
return to near normal over the weekend as high pressure weakens.
An upper-level ridge of high pressure remains anchored over
southern Nevada this evening. A very warm weather pattern will
continue into Friday. Onshore flow will keep a some marine
influence in play, especially near the coast, but the marine
layer will remain shallow. Patchy dense fog will continue to
plague the central coast late tonight and early Friday morning
and possibly portions of the Santa Barbara South Coast. Current
forecast looks agreeable and no updates are planned at this time.
Minimal changes to the forecast for the next seven days. Low level
temps are expected to increase Friday as models show a 1-2 mb
offshore trend in surface pressure gradients. This should lead to
1-3 degree warmup in most areas, otherwise tomorrow should look
and feel a lot like today. Solid but shallow marine lyr along the
central coast with areas of dense morning fog. Patchy and shallow
in the south.
Models continue to trend slightly cooler through the weekend as
high pressure weakens and gradients weakly trend onshore. Still
4-8 degrees above normal for inland areas Saturday then just 2-4
degrees above normal Sunday.
Still a small chance of convection in the la/Ventura mtns and av
over the weekend as air mass becomes a little more unstable. Still
not much moisture to work with so not a big precip threat. Mainly
gusty winds and possibly an isolated dry lightning strike or two.
Of the two days this weekend models currently favoring Saturday
slightly over Sunday.
Minimal changes through the work week next week as temperature and
gradient trends are Pretty Flat. Main thing will be the potential
for thunderstorms Monday as today's GFS was actually a bit wetter
than earlier runs and the European model (ecmwf). I've gone ahead and extended the
small weekend pops to Monday for the mtns and av. After that the
models are in decent agreement showing the moisture boundary
shifting well east of the area.
At 23z, the marine layer was around 800 feet deep at klax. The
top of the inversion was near 4300 feet with a temperature around
29 degrees celsius.
LIFR to IFR conditions will likely spread into coastal terminals
through 13z. The highest likelihood on LIFR conditions exists for
coastal terminals north of koxr. Conditions should improve to VFR
between 15z and 19z.
Klax...low confidence with return of IFR cigs between 10z and 16z.
There is a 30 percent chance that VFR conditions could persist
through entire forecast period.
Kbur...high confidence in VFR conditions through period.
High confidence exists in the forecast through Saturday.
Widespread dense fog will continue across the coastal waters,
mainly northwest of The Channel islands, as shallow marine layer
remains in place. Weak to locally moderate northwest winds will
kick up each afternoon near the islands and across the outer
waters, with gusts of 20 to 25 knots through the early evening
hours. A Small Craft Advisory is in effect through late tonight
for the southern outer waters, and this advisory has been extended
for the waters from Point Sal to Santa Cruz Island and westward
60 nm into Saturday morning. There is a 50 percent chance that the
advisory for the outer waters south of Santa Cruz Island could be
extended into Saturday morning.
A small but long period southerly swell will develop Saturday
night through Sunday. Not anticipating any issues.
Pz...Small Craft Advisory in effect until 3 am PDT Saturday for
zone 673. (See laxmwwlox).
Small Craft Advisory in effect until 3 am PDT Friday for zone
676. (See laxmwwlox).