Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 201801
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1101 AM PDT Thu Oct 20 2016
...Aviation discussion updated...
High pressure will bring gusty offshore winds today with
temperatures at near record levels. Warm temperatures will
continue Friday, then a broad upper level trough of low pressure
will affect the area this weekend into early next week, with
cooler temperatures and possible precipitation from late Sunday to
Monday. Onshore flow will increase next week for a deep marine
layer and below normal temperatures.
Warm start to the day across the region, about 3 to 8 deg warmer so
far than yesterday for many areas. As such, we are on track for even
hotter temps than yesterday, with widespread 90s to around 100 for
the coast, vlys and foothills. These temps will be about 12 to 20
deg above normal. Several records highs may be tied or broken today,
including at downtown L.A. (forecast hi 98, record 96 set in 1964),
Long beach (forecast hi 99, record 98 set in 1965), and Camarillo
(forecast hi 97, record 96 set in 1965). Winds are not as strong as
yesterday, with the strongest gusts up to 40 to 45 mph noted in the
foothills and mtns, and 20 to 30 mph for the coast and vlys.
Pressure gradients continue to be rather strong offshore (e.g., -6.4
mb LAX-DAG at 15Z) which will help to bring some advisory level
gusts of about 40 to 50 mph to portions of the VTU/L.A. County vlys,
mtns and VTU County coast thru about noon. The dry offshore flow
will keep sunny skies across sw CA thru today.
The upper ridge will peak over the area today with 500 mb heights
589 to 590 dm. The upper ridge will gradually weaken and move e
tonight and Fri as a broad upper level trof over the ern Pac
approaches the area. This ern Pac upper trof is forecast to
gradually move toward the forecast area thru Sat, with a broad sw
flow aloft and gradually lowering 500 mb heights.
Mostly clear skies will continue over swrn CA tonight thru Sat.
There will be one more round of offshore winds with the tail end of
this Santa Ana event tonight and Fri morning. Gusty northeasterly
sub-advisory winds are expected for the favored areas of VTU/L.A.
Counties, and locally for parts of SLO County. Low temps tonight in
the breezy valley and foothill areas will be warm and likely remain
in the 70s.
Daytime highs will be cooler Fri but still 10 to 18 deg above normal
with the inland coastal areas, vlys and foothills reaching the mid
to upper 90s. Increasing onshore gradients and earlier onset of the
seabreeze for Sat will help drop temps up to 10 deg cooler, with
highs in the warmest vlys and foothills in the mid 80s to around
***FROM PREVIOUS DISCUSSION***
Not much change in the thinking for the Sunday forecast. Strong
SW flow aloft will move in over the state as another strong storm
approaches the PAC NW. Heights will fall to 579 DM and onshore
flow will increase. Skies will turn partly cloudy as mid level
moisture streams in. Afternoon maximum temperatures will fall to
The EC continues the thinking of a small trof moving over SRN CA
later Sunday night and Monday. This agrees with its previous runs
and earlier runs of GFS. The current GFS however now forecasts the
energy and moisture to remain to the south. One mdl run does not
a trend make and will keep the current mostly cloudy with slight
chc of rain forecast going. But will have to keep an eye on the
Both GFS and EC agree the SW flow will continue over the area for
Tuesday and Wednesday. Embedded mid and high level moisture will
keep skies partly cloudy. Max temps will be near normal.
At 18Z at KLAX... There was no inversion.
Overall... High confidence in the 18z TAFs. Gusty north to
northeast winds at KOXR, KCMA and KVNY due to Santa Ana winds and
light to moderate LLWS/Turbulence over and near higher terrain.
Otherwise and elsewhere VFR conditions will prevail throughout the
KLAX... High confidence in the 18Z TAF. There is a fifteen
percent chance of northeasterly winds reaching 8 knots through
20Z. Otherwise VFR conditions will prevail throughout the forecast
KBUR... High confidence in the 18Z TAF. There is a fifteen percent
chance of LLWS/Turbulence through 22Z today. Otherwise VFR
conditions will prevail throughout the forecast period.
A Small Craft Advisory is in effect through noon for the northern
outer waters and the nearshore of the Central Coast due to strong
northerly winds. There is also a Small Craft Advisory in effect
through noon for the inner waters - particularly along the
Ventura and Los Angeles County coast - due to the Santa Ana wind
flow. The strongest winds will be below passes and canyons.
Winds will diminish slowly this afternoon and conditions should
remain below advisory thresholds tonight through Sunday. There is
a thirty percent chance of local gusts to 30 knots that will clip
the northwest portion of the northern outer waters tonight
.FIRE WEATHER...20/900 AM
Continued elevated to critical fire danger today as Hot and dry
conditions today with widespread 90s to near 100 degrees and
minimum humidities in the single digits. Offshore wind gusts of 35
to 50 mph across Santa Ana prone mountain locations with 25 to
locally 40 mph across favored valley and coastal areas through
this afternoon. The winds are expected to weaken through this
evening with red flag conditions on track to end for coastal and
valley areas during this time despite continued dry conditions.
Continued gusty offshore winds of 25 to locally 40 mph with single
digit humidities across the mountains through Friday early
afternoon also combined with the critical fuels may prompt the
extension of Red Flag Warnings for the mountains through this
time. The current Red Flag Warnings look good and will make any
updates with the afternoon package. Elevated fire danger is
expected to continue Friday for coastal areas and Saturday for
most interior areas.
An approaching trough of low pressure this weekend will support
gradual cooling with increases in relative humidities, especially
near the coast. However, elevated fire danger will continue for
interior areas early in the weekend and at higher elevations. Low
confidence in the weather pattern for next week and cannot rule
out showers at some point for the early to middle of next week nor
another north to northeast wind event by the middle to end of the
CA...Wind Advisory in effect until noon PDT today For zones
40-44>46-53-54-547. (See LAXNPWLOX).
Red Flag Warning in effect until 8 PM PDT this evening For
zones 240-241-244>246-253-254. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until noon PDT today For zones
645-650-655-670. (See LAXMWWLOX).