Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
925 am PST sun Feb 1 2015
high pressure aloft will result in dry weather and slightly above
normal temperatures for much of this week. A frontal system may
bring some light rain to the central coast Friday into Saturday.
Short term (today-tue)...update...
latest visible satellite imagery indicated less in the way of low clouds
across San Luis Obispo County interior areas compared to yesterday
at this time. Low clouds should scour out of Paso Robles several
hours earlier than yesterday. Otherwise skies were clear except for
a small band of patchy low clouds between Long Beach and near lax.
This should scour out by 10 am. As far as the forecast GOES...looks
to be in great shape with no changes anticipated this morning with
mostly sunny skies expected today. There will be some variable high
clouds moving around the upper ridge across the sky later today. A
quick look at the long term forecast shows that both the GFS and
European are coming into better agreement that light rain will
affect areas north of Point Conception by Friday afternoon into early
***From previous discussion***
Low level gradients were weakly offshore...and there were some gusty
winds in the mountains of l.A. And vtu counties. Some gusty winds could
push into the valleys of l.A. And vtu counties this morning...but winds
will remain well below advisory levels. Maximum temperatures today should be up
a couple of degrees in most areas...generally several degrees above
normal for the first day of February.
The positively tilted upper ridge building into central California today
will become more neutrally tilted Monday and Tuesday...with the ridge axis
moving across the region on Tuesday. Some low clouds may develop across
coastal sections of l.A. County tonight/Monday morning...with a better
chance of night through morning low clouds/fog in coastal sections
of l.A. County...portions of the central coast...and possibly the
San Gabriel valley Monday night/Tue. Heights/thicknesses change rather
little through Tuesday...but offshore gradients do turn onshore...and
increase...especially on Tuesday. Overall...expect mostly minor changes
in maximum temperatures Monday and Tuesday from those observed today...although there
will probably be at least a couple of degrees of cooling on the
coastal plain and in the Lower Valley locations.
Long term (wed-sat)...the upper high will actually amplify a bit
over the region Wednesday and Thursday as a broad trough moves into the eastern
Pacific. Expect a fair amount of high clouds...and any night through
morning stratus will likely remain confined to the coastal
plain...and possibly Lower Valley locations such as the Santa Ynez
Valley and the San Gabriel valley. Maximum temperatures will probably edge
upward a couple of degrees...especially away from the coast.
A frontal system will move into northern California on Friday...and while most
of its moisture will likely remain north of the region...there is a
slight chance of light rain or showers Friday afternoon through early
Sat north of pt Conception. Otherwise...there should be a fair amount of
high cloudiness. Heights will actually rise...especially across southern
sections of the forecast area...so there could be a bit of warming...but
there will probably be enough thick high clouds to temper and
warming. The upper ridge will amplify again Sat...forcing any
moisture well to the north of the region...and likely bringing a few
degrees of warming to most areas.
At 1635z...the inversion at klax was based at 1100 feet. The top of
the inversion was at 2300 feet with a temperature of 17 degrees
Overall...moderate to high confidence in 18z taf package. VFR conds
anticipated for all sites this afternoon/evening (as current
vlifr/LIFR conds at kprb and klgb should dissipate quickly).
Overnight...expect the marine layer to begin to make a return to
some coastal sites (klgb/klax/ksmx) with MVFR/IFR visibilities and IFR
ceilings. Also...likely another round of vlifr conds at kprb late
Klax...moderate confidence in 18z taf. High confidence in VFR conds
through this evening. Moderate confidence in return of IFR ceilings
tonight...but low confidence in timing (could be +/- 2 hours of
current 12z forecast).
Kbur...high confidence in 18z taf.