Scientific Forecaster Discussion
Southwest California area forecast discussion
National Weather Service Los Angeles/Oxnard California
820 PM PST Thursday Jan 29 2015
a trough of low pressure will bring moist northeast flow into the
area...with a few showers possible for Los Angeles County Friday and
Friday night. Offshore winds will increase by Saturday night through
Sunday morning. High pressure will bring warmer temperatures and
mostly clear skies over the weekend and into next week.
Short term (tonight-sun)...an upper level trough extending from off
of Baja California into California was continuing to stream moisture into the forecast
area this evening by way of middle and hi clouds. The cloudiness was
confined mainly to Ventura and Los Angeles counties. Radar was
showing some light rain showers or sprinkles over portions of l.A.
County as well. Little change in this pattern can be expected
overnight. Patchy dense fog will once again be possible in the
Salinas River Valley late tonight. Will update the zones this
evening to add light showers or sprinkles to l.A. County overnight.
The upper trough will strengthen into an upper level low over southeastern California
on Friday...then move very little Friday night. The upper low will be
shunted south on Sat as an upper ridge builds into northern California. The
upper ridge is forecast to move into central California by Sun morning. A
slight chance of showers overall can be expected for much of l.A.
County on Friday and Friday night...with a few leftover showers on the north
slopes of the san Gabriels Sat morning. Rainfall amounts will be
light where rain occurs...with generally less than 0.10 inch...although
most areas should less than 0.05 inch. Any snow in the mountains
will be confined to elevations generally above 7000 feet and be very
light. Otherwise...varying amounts of clouds will prevail Friday into
Sat morning for vtu/l.A. Counties...with clear to partly cloudy
skies over slo/sba counties. Skies should become mostly clear for
all areas by later Sat and continue through sun. Weak offshore flow
will continue Friday morning...then increase and become gusty
especially over higher terrain Friday night into Sat morning...and
again Sat night into Sun morning. Some gusts in the l.A./Vtu County
mountains could approach advisory levels at times over the weekend. Temperatures
across the region are expected to be near to slightly above normal
on Friday...then warm to several degrees above normal in all areas by
***From previous discussion***
Long term (mon-thu)...a moderately strong ridge of high pressure
(especially for january) will settle over the West Coast next week
and remain there for most if not all of the week. Above normal
temperatures will predominately clear skies will be the normal.
Pressure gradients will be around neutral through the period...with
not much in the way of winds to mention.
At 2305z...there was a surface based inversion at klax...with the
inversion top at 800 feet and a temperature of 21 degrees celsius.
Generally hi confidence in the 00z tafs...except moderate confidence
at kprb...where there is a 50-60 percent chance of LIFR conditions
late tonight and Friday morning. Otherwise...mostly VFR conditions with
varying amounts of mainly middle and hi clouds are expected at the
airfields through Friday. Periods of MVFR visibilities are also expected later
tonight and Friday morning at ksbp...klax and klgb. In addition...lower
level clouds with VFR ceilings should affect klax and klgb on Friday...with
a 20 percent chance of MVFR ceilings at times. There is a 20 percent
chance of showers in Los Angeles County Friday afternoon and evening.
Klax...hi confidence overall in the 00z taf. VFR conditions with
mostly middle and hi clouds are expected through Friday morning. A period of
lower level clouds and VFR ceilings are expected Friday afternoon and
evening...with a 20 percent chance of MVFR ceilings at times. There is
also a 20 percent chance of showers Friday afternoon and evening.
Kbur...hi confidence in the 00z taf. VFR conditions with mostly middle
and hi level clouds are expected through Friday afternoon. There is also a
20 percent chance of showers Friday afternoon.
Outer waters...Small Craft Advisory level winds will persist through
late Friday night...and while winds may diminish some Friday morning
they are expected to increase again Friday afternoon. A building
long period west swell will affect the waters tonight into Saturday.
Inner waters...from between Ventura and Malibu...NE winds 10 to 20
knots late Friday night into Saturday morning...and 20 to 25 knots
Saturday night into Sunday morning. 70 percent chance for a Small
Craft Advisory for Sunday morning for this area.
Small Craft Advisory (see laxmwwlox).