Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
350 am PST Friday Nov 28 2014
The large ridge overhead will slowly flatten and offshore breezes
will gradually turn onshore...beginning a cooling trend on Friday
and through the weekend. There is a chance of light rain on the
central coast on Sunday...but only a slight chance south. The next
chance of rain appears to be Tuesday or Wednesday.
Short term (today-sun)...
the upper high that has dominated the recent weather will flatten
today. At the same time the offshore flow which has persisted since
last Sunday will weaken and should turn onshore this afternoon. Some
actual stratus covers the beaches of the central coast. All of this
will combine to cool things off from yesterdays very warm day (the
2nd warmest Thanksgiving recorded at downtown l.A. 89 vs 90 degrees
The cooling trend will continue Saturday as a weak eddy and onshore
flow will bring some stratus to the central coast and the la coast.
Maximum temperatures will fall about 8 degrees across most of the coasts and
valleys save the central coast which will see its big cool down today.
Still many maximum temperatures will be a degree or two above normal.
A weak front will sag across the central coast Sat night and will
bring clouds and slight chance of light rain nothing more than a
tenth. South of Point Conception a deep marine layer cover the
coasts and valleys.
On Sunday a weak warm front will set up over the area and will bring
mostly cloudy skies to the area along with a slight chance of rain but
the rain chance is looking more and more unlikely. Maybe some drizzle
or some sprinkles. Maximum temperatures will fall a few more degrees.
Long term (mon-thu)...
long range models are finally beginning to exhibit some agreement and
consistency. Both now bring a weak pop up ridge to the area Monday.
This should allow for some clearing...dry conditions and a couple of
degrees of warming.
Both ec and GFS agree (for now) that and upper low will move into
position west of sfo. A cold front is forecast to move up in the SW
flow and bring rain to the area early Tuesday morning into early
Wednesday morning with perhaps a 4 to 6 hour period of decent rain.
The southwest flow will keep snow levels very high and this will be
a rain only event. If this scenario comes true we might see an inch
of rain across the csts and valley and 1 to 3 inches in the mountains with
lesser amounts inland. Did not introduce any probability of precipitation higher than 50
into the forecast because have next to no Faith the models will have the
same forecast today so will hold off of the higher probability of precipitation until there
is some run to run consistency.
A series of impulses will ride in behind the main system keeping the
area mostly cloudy with a chance of rain. Also there is a chance the
storm forecast for Tuesday will be delayed again and its rain will
arrive a day or two later than currently forecast.
Clear skies and VFR conds expected across the region through this
evening...except some IFR conds are possible on the central coast
through middle morning. Expect more widespread IFR conds on the central
coast and across coastal sections of l.A. County late tonight/Sat
At lax at 0915z there was a surface based inversion. The inversion
top was 1700 feet with a temperature of 24 degrees c.
Klax...high confidence in the 12z taf with ceiling and visibility unlimited conds through
this evening. There is a 20 to 30 percent chance that IFR ceilings will
not materialize tonight.
Kbur...high confidence in the 12z taf with ceiling and visibility unlimited conds through the period.
High confidence that wind and sea conds will remain below Small Craft Advisory levels
through Sat evening. There will be an increasing chance of Small Craft Advisory level
S winds late Sat night across the outer waters...with Small Craft Advisory conds
becoming fairly likely across the northern two thirds of the outer
high rip current risk (see laxsrflox).