Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 251557
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
857 AM PDT Sat Mar 25 2017
There will be a few lingering showers mostly across the mountains
today with below normal temperatures. It will be mostly sunny
Sunday with a few degrees of warming. On Monday a weak trof will
result in clouds a few light showers over SLO and Santa Barbara
counties. Gusty northerly winds will set up Monday night and
persist into Tuesday. Weak ridging aloft and northerly winds at
the surface will bring warm and dry conditions for the middle of
An upper trof and dissipating cold front was over srn CA this
morning. A few lingering showers were noted on RADAR mainly over SBA
County and were moving e. Widely scattered showers and mtn snow
showers may persist across portions of the forecast area this
morning and linger on the n mtn slopes this afternoon. Otherwise,
skies are expected to become partly cloudy for much of the area by
midday and thru this afternoon. Any additional precip will be light
and less than 0.05 inch. Temps today will be several degrees below
normal throughout the region. Highs in the warmest vlys and inland
coastal areas should reach the mid to upper 60s this afternoon.
The upper trof will move well e of the forecast area this afternoon,
with weak upper ridging over srn CA tonight and Sun. A fast-moving
upper level trof will move thru the e Pac and into CA Sun night,
followed by an inside slider quickly moving thru CA on Mon.
The north mtn slopes should have persistent upslope clouds with a
few rain and snow showers tonight, while elsewhere clear to partly
cloudy skies should prevail. However, the 12Z NAM is indicating an
eddy with possible low clouds developing over the L.A. County coast
and some vlys later tonight. Clear to partly cloudy skies overall
should prevail across the region on Sun. The upper trof Sun night
will bring some increasing clouds and a slight chance of showers
over SLO/SBA Counties. As the inside slider moves inland on Mon, a
slight chance of rain and snow showers can be expected mainly on the
n mtn slopes to the Cuyama Vly. Otherwise, partly cloudy skies
overall should prevail across much of the forecast area thru the
day. A tightening northerly pressure gradient and some cold air
advection Mon afternoon will help to bring strong and gusty nw winds
to the mtns and Antelope Vly, as well as gusty nw winds to the
Central Coast. Wind advisories will likely be needed for these areas
Temps Sun and Mon are forecast to be several degrees below normal
for many areas. Highs in the warmest vlys and inland coastal areas
should reach the upper 60s to low 70s both days, altho the Antelope
Vly will turn much cooler on Mon with highs 4 to 8 deg below normal.
***FROM PREVIOUS DISCUSSION***
The biggest weather news for the next 7 days will occur Monday
night and Tuesday. Good north flow both SFC and aloft along with
cool air advection will set up behind Monday`s weak trof. Strong
and gusty north winds will develop through and below the northerly
oriented passes and canyons. The i-5 corridor and the SBA south
coast will see the strongest winds. The wind speeds will be
strong advisory levels for sure and possibly warning levels. The
winds will turn to the NE during the day on Tuesday. Otherwise a
building ridge will provide clear skies and will combine with the
offshore flow to bring a 6 to 12 degree bump up in temps. There
may be a few 80 degree readings in the vlys.
The ridge peaks on Wednesday and with continued albeit weaker offshore
flow Wednesday will be the warmest day of the next 7 with all of
the vlys in the 80s and most of the coasts in the mid to upper
70s. Max temps will be 6 to 12 degrees above normal.
Big mdl differences for Thursday with the GFS continuing the
ridging and warm temps. The EC on the other hand has cooler NW
flow. GFS has been the more consistent of the mdls and favored the
warmer solution in the forecast.
Both mdls show an inside slider for Friday which will bring cooler
temps and will set up another offshore wind event.
At 1230Z, the moist layer was around 1500 ft deep. There was a
weak inversion around 2400 ft deep. The temperature at the top of
the inversion was around 11 degrees C. This is part of a
deepening moist layer.
Low confidence with 12Z TAFs. Cigs will fluctuate between VFR and
MVFR through 19z in most locations. Otherwise expect VFR conds
later this afternoon as front pushes east. There is a 40% chance
that MVFR cigs could linger near the foothills into this
afternoon. There is a 10% chance that IFR cigs will occur after
06z this eve.
KLAX...Low confidence with 12z TAF through 20z. Then better chance
for VFR with 30% chance for MVFR cigs into this afternoon. Lower
confidence with cigs after 06z this eve. Higher likelihood of
MVFR Cigs and vsbys after 08z tonight.
KBUR...Moderate confidence in 12z TAF. Cigs will fluctuate between
VFR and MVFR through this afternoon. There is a 20% chance for IFR
conds after 10z Sun morning.
For the Outer Waters, moderate to high confidence in current
forecast. High confidence in winds increasing to Small Craft
Advisory (SCA) levels this afternoon and continue through Sunday
morning. By Sunday afternoon/evening, moderate confidence (60%) in
winds increasing to Gale force levels with a good chance of winds
remaining at Gale force levels through Wednesday.
For the Inner Waters, moderate confidence in current forecast. For
the waters north of Point Sal, there is a 40% chance that winds
will increase to SCA levels this afternoon/evening. From Monday
through Wednesday, moderate confidence in winds increasing to SCA
levels each afternoon/evening. For the waters south of Point
Conception, moderate confidence in winds increasing to SCA levels
this afternoon/evening across the western half of the Santa
Barbara Channel, but remaining below advisory levels elsewhere.
For Sunday afternoon through Monday, there is a 50% chance of SCA
level west winds developing. For Monday night and Tuesday, the
winds will shift to an offshore direction (north to northeast)
with a chance of SCA level gusts from Ventura south to Santa
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
PM PDT this evening for zone 650. (See LAXMWWLOX).
Small Craft Advisory in effect from 3 PM this afternoon to 3
PM PDT Sunday for zones 670-673-676. (See LAXMWWLOX).
Gale Watch in effect from Sunday afternoon through late
Sunday night for zones 673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
A weak weather system will bring some showers and mountain snow
showers to SLO County and the north mountain slopes on Monday.
Gusty northwest to northeast winds will affect the area at times
Monday through Friday. The winds should cause some travel issues
at times during the period. Winds may be strong enough in some
areas for small trees or tree branches to be knocked down.