Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 092237
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
237 PM PST Fri Dec 9 2016
A series of weak disturbances will continue to bring periods of
light rain to the area through Sunday morning. Expect another
round of light showers midweek for the Central Coast, becoming more
potent and widespread later in the week.
Plenty of clouds continue to stream across the forecast area today
as a moist west to northwest flow pattern prevails. There has been
a break in precipitation today, but short range models continue to
show another wave of more organized precipitation moving into the
Central Coast later this afternoon into tonight where light rain
will become likely. Precipitable water values continue to hover
around 1.1 inches off the Central Coast this afternoon, with
values as high as 1.5 inches a couple hundred miles off the coast
to the west. Have already seen some rainfall amounts exceed one
inch across the northern coastal areas and foothills of SLO
County, with Cambria checking in at 1.62 inches as of 11 am.
12z and 18z NAM cross sections continue to show another increase
in low level moisture for areas south of Point Conception later
tonight into Saturday morning, so could see areas of drizzle and
a 20 percent chance of measurable light rain. Another band of
light rain is expected to hit the Central Coast later Saturday
afternoon and evening, with a 20 percent chance of light rain
extending into LA/Ventura counties later Saturday night. There
will also be some gusty west winds across interior section on
Saturday and Saturday evening, shifting to a more northwest
direction late Saturday night into Sunday. At this point, mostly
expecting to see wind gusts in the 35 to 45 mph range, remaining
just below advisory levels. Drying trend later Sunday into Monday
however still expecting plenty of mid and high level clouds to
drift over the area. Continued mild temperatures through the
Overall, 00Z models do not exhibit the best of synoptic agreement.
At upper levels, westerly flow will remain over the area Monday
and Tuesday. On Wednesday, the GFS brings a weak disturbance over
the area while the ECMWF has a ridge. On Thursday, both models
indicate another decent system will impact the district. Near the
surface, onshore flow will continue.
Forecast-wise, Monday and Tuesday will be partly cloudy and dry
with a slight warming trend. On Wednesday, will keep the forecast
dry for now (given the model discrepancies), but would not be
surprised to see pops added by later shifts. For Thursday, models
differ a bit with timing, but both indicate the potential for a
rather wet storm to impact the area. Will indicate an increasing
chance of rain Thursday afternoon and Thursday night.
At 18Z, there was a moist layer below 8000 ft but no marine layer
Moderate confidence in bkn015-25 most common today over coastal
sites...but low confidence in timing and presence of any breaks.
70 percent chance of KSBA having cigs under 010 through 23Z, 30
percent chance of persisting through Saturday. Expecting similar
cig/vis behavior tonight as last night, but with less rain and
drizzle amounts and longevity.
KLAX...Moderate confidence in bkn015-25 most common today, but low
confidence on presence and timing of any breaks. There will likely
be some improvement 03-09Z, but not sure for how long. 60 percent
chance of MVFR cigs returning after 09Z tonight. 20 percent chance
for -RA/-DZ Saturday morning.
KBUR...Moderate confidence in VFR conditions through 08Z tonight
with sct-BKN mid-level clouds. 60 percent chance of MVFR cigs
after 08Z...30 percent chance of IFR. 20 percent chance for
-RA/-DZ Saturday morning.
Gusty west winds (20-25 KT) will expand into this evening south
of Point Conception, especially impacting areas around the
Channel Islands and to the south where a low-end Small Craft
Advisory (SCA) will be posted. These winds will persist through
Saturday night and should expand some on Saturday. A SCA may be
needed for the Santa Monica Basin either tonight (30 percent) or
on Saturday (60 percent). These winds will also create a building
short period swell (4-6 feet at 6-8 seconds). NW winds will likely
reach SCA levels across the outer waters late Sun through at least
PZ...Small Craft Advisory in effect until 3 AM PST Sunday for
zones 650-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
There is the potential for widespread rains and gusty winds later
next week. Still considerable uncertainty in timing and amounts
from this storm, but most likely impacting the area sometime
between Thursday and Friday. There is the potential for a cold and
unsettled pattern lingering into next weekend, with a threat of
rain showers and mountain snow.