Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
1040 am PST Friday Dec 26 2014
..new aviation discussion...
High pressure building into the Great Basin will produce gusty north
and northeast winds for parts of the area through Saturday and
mostly clear skies through the weekend. A large low pressure system
may bring unsettled weather to the region for the early and middle
part of next week. Temperatures will remain slightly below normal
through the weekend...with cooler conditions possible next week.
Short term (today-mon)...
Chilly start this morning despite the offshore flow in Ventura and
la County. All of the freeze and hard freeze warnings for last night
and early this morning verified. Tonight and tomorrow morning will
be just as cold or even slightly colder for the wind sheltered
areas...so freeze and hard freeze warnings will remain in place for
those areas. May also have to consider issuing a freeze warning or a
frost advisory for the central coast zones...as a couple isolated
areas got a little colder than expected last night.
Today will be bright and sunny...but cool and breezy for parts of la
and Ventura County that are normally affected by Santa Ana winds.
The lax-dag gradient this morning is about -2mb...which is a fairly
weak offshore gradient. But with decent upper-level support and cold
air advection...NE winds have still been gusting 40-50 miles per hour in the
mountains this morning. Winds in the valley areas have remained
mostly below advisory level so far...but will see what happens in
the next couple of hours. Wind advisories in la and ventua County go
through 3pm this afternoon. These will be extended through Saturday
afternoon...as the NAM strengthens the lax-dag gradient to -5mb by
The other item of interest today will be the Big Cutoff low that
develops by the middle of next week. Most likely won't be able to
pin the forecast details down with that this afternoon...but will
take a look.
***From previous discussion***
Sunday and Monday will have a few more clouds and less wind. Maximum
temperatures will be a degree or two warmer.
Long term (tue-thu)...
the extended forecast will be dominated by a very large and very
cold upper low that will spin out of a trough that started out in
Alberta Canada. These systems typically confound all attempts to
forecast them until they are about 3 days away. Here at day six
there is Little Hope getting the forecast track of the low correct.
So it is no surprise that all of the long range models are exhibiting
zero agreement with each other or their own previous runs.
Unfortunately the forecast is very dependent on the track of the low
a west Ward arc will bring rain sometimes a lot of rain to the area
while a inside track brings very windy and dry conditions. Anything
in between results in a mix of things. It will be very cool perhaps
even very cold.
For now broad brushed in 20 percent probability of precipitation (an 80 percent chance of no
rain) across the area with cloudy skies and below normal temperatures. Will
come back tonight and hope for sign of what direction to point the
At 1749z...there was no inversion at klax.
VFR conds expected through the period. Areas of gusty north to NE winds will
affect l.A. And vtu counties through early afternoon...and again
late tonight/Sat morning.
Klax...high confidence in the 18z taf. VFR conds will continue
through the period. There is a 10 to 20 percent chance of northeasterly winds
reaching 8 to 10 knots Sat morning between 11z and 15z.
Kbur...moderate to high confidence in the 18z taf. VFR conds will
continue through the period. There is a 20 percent chance gusty north to
northeast winds could surface before 20z this morning.
Marine...26/900 am PST...
for the outer waters...northwest to north winds were near Small Craft Advisory
levels...and will diminish by afternoon. Seas at or above 10 feet
will subside below 10 feet during the afternoon.
Across the inner waters...moderate confidence in Small Craft Advisory conds through
early afternoon due to winds from Oxnard to Point Mugu and out to
anacapa and Santa Cruz Island...near shore from Point Mugu to Santa
Monica...and through portions of the San Pedro Channel.
Small Craft Advisory conds will probably affect there areas again Sat morning.
hard freeze warning (see laxnpwlox).
Freeze warning (see laxnpwlox).
Wind Advisory (see laxnpwlox).
Small Craft Advisory (see laxmwwlox).
High rip current risk (see laxsrflox).