Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
815 PM PST Thursday Nov 27 2014
Updated aviation section
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)...
today was a very warm Thanksgiving day across the region. Many
locations experience their warmest or second warmest Thanksgiving
day on record...keeping in mind that the date of Thanksgiving varies
from year to year. A handful of daily record high temperatures for
November 27th were also set today.
Gradients were still -4 mb offshore between klax and kdag this
evening...stronger than initialized by the WRF. While there is zero
support for winds...there may be some locally
gusty winds in the mountains of l.A. And vtu counties overnight and early
Friday morning. It remains very warm just above the surface...with 950 mb
temperatures still near 27c or 80f. Expect another warm night in the
foothills and where it remains breezy. Do not expect any stratus
across the region tonight...although with some stratus lurking off
the central coast...confidence is a bit lower there.
Gradients are forecast to turn onshore Friday afternoon...but it should
still be another warm day...especially the valleys and interior
portions of the coastal plain in l.A. And vtu counties.
..from previous forecast...
A Little Eddy and a general onshore push should bring back the
marine layer on Saturday morning. By the afternoon we should be
seeing some clouds in advance of the weather systems that will drive
the narrative for next week. The onshore winds and cloud cover
should have US back down to seasonal temperatures by Saturday.
Sunday is something of a transition day as the first in a series of
low pressure waves enters the area. Everywhere in the area will be
cloudier and the temperatures will continue to drop. Models in pretty good
agreement that northwest slo County should get some measurable rain
by Monday morning but not expecting more than a tenth to a quarter
inch. The rest of the area could see some light rain so have some
probability of precipitation in the forecast but really not expecting more than a tenth
anywhere if even that much.
Long term (mon-thur)...
the aforementioned model agreement? Its just not there from Monday
through the rest of the period. As discussed in earlier afds...the
problem is the track and intensity of an upper low that forms over
the Aleutians Friday evening and then takes a south-southeast track to a point
about 1200 miles west of pt Conception. After it gets there on
Sunday night there is no agreement on how far or fast this low will
track to the east nor on how much moisture it will entrain on its
eastward journey. The GFS remains fast and wet with good rainfall
Tuesday and Wednesday. The ec is much slower and brings in a storm
with less rainfall Wednesday that lingers to Friday.
Keeping a generalized cloudy forecast with a chance rain going each
day in the extended until there is more agreement. In either
solution we should get at least some rain next week and any is
welcome...but it will take many many rain events to ultimately give
California the drought relief it needs.
clear skies and VFR conds expected across the region through the
At lax at 2230z there was a surface based inversion...with an
inversion top is of 1400 feet with a temperature of 27 degrees c.
Klax...very high confidence in the 00z taf with ceiling and visibility unlimited conds through
Kbur...very high confidence in the 00z taf with ceiling and visibility unlimited conds through
A low pressure system in the eastern Pacific today is expected to
move east while weakening through Friday. A trough of low pressure
will then persist over the eastern Pacific Friday through Saturday.
A warm front will move over the coastal waters Sunday while low
pressure develops and deepens over the eastern Pacific. South winds
will develop Sunday and possibly create Small Craft Advisory
conditions from the northern Channel Islands to Point Piedras
Blancas. As the low pressure system shifts east and approaches the
coast next week Monday through Tuesday seas generated south of the
low center within a limited fetch area and oriented between 240-270
degrees relative to the area are expected to begin to arrive late
Tuesday and build through Wednesday and small craft for hazardous
sea conditions area possible.