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fxus66 ksgx 162302 

Area forecast discussion
National Weather Service San Diego California
300 PM PST Sat Nov 16 2019

Santa Ana winds will prevail through Monday with locally strong
winds occurring along the coastal mountain slopes and through
valley corridors below passes and canyons. The strongest winds
will occur after midnight tonight through Sunday afternoon. Winds
will subside on Monday, but low humidity will remain inland from
the coast. On Tuesday, winds will turn onshore ahead of a storm
system approaching from the north. The first winter storm of the
season will arrive from the north Tuesday night, moving over
Southern California Wednesday through Thursday. This will deliver
the first widespread, and potentially significant, precipitation
of the season to socal. The precipitation will gradually taper off
Thursday night into Friday as the storm departs to the east.
Upper level high pressure will build in from the west next


Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino


* red flag warning for inland parts of socal 1am-6pm Sunday
* first winter storm of the season to impact socal mid week

Santa Ana winds have have returned to Southern California and
will peak late tonight-Sunday with Max gusts to 50 mph in the
favored areas, such as below the Cajon Pass, Santa Ana foothills
(freemont canyon), below the San Gorgonio Pass and along the
coastal mountain slopes of the San Diego County mountains.
Relative humidity has lowered into the teens into portions of the
inland valleys. Critical fire weather conditions will occur in the
wind-prone areas late tonight through Sunday afternoon. High
temperatures will soar with some inland valley locales reaching into
the lower 90s with a few record highs possible. See fire weather
section below for more details on the fire weather concerns late

Santa Ana winds will subside on Monday and winds by Tuesday
transition back to onshore ahead of the first winter storm of the
season poised to impact Southern California during the middle
part of next week.

There is high confidence that widespread precipitation will occur
across socal Wednesday-Thursday, but there is low confidence on
the details.

A cut off low off the Baja Peninsula will meander there through
Monday. Southerly mid/high level wind flow on the east side of
the low will slowly draw moisture northward from Tropical Storm
Raymond, but that moisture stays south of the border through
Monday. On Tuesday, a northern stream shortwave will dive
southward and into socal Wednesday-Thursday. However, GFS and
European model (ecmwf) and their ensembles diverge with regards to the track of
the low. The 12z run of the GFS is over socal and more open,
while the European model (ecmwf) has a track over the ocean, closing off, slower
and grabbing more moisture, and hence is a wetter scenario.

There is an extremely large spread with regards to rainfall
amounts when looking at ensemble model data, ranging from light
amounts (around 0.10 inches) to hefty amounts (3-4"+). Our current
forecast is placed towards the mean, depicting a widespread
0.50-1.00 inches. Nbm is slightly higher overall with a more
coastal focus. Trended towards nbm, but did weigh some of the
inherited forecast to trend/not jump. Quantitative precipitation forecast adjustments will be the
norm in the coming days. Users should keep in mind that a wide
range of solutions is possible, ranging from little rainfall to
significant rainfall, capable of producing flash flooding.
Mountain snowfall will depend on the low track as well. Currently,
the snow level is forecast to fall to around 6000 feet with
several inches of snow possible above. Thunderstorms may occur
with this storm system as some runs do show enough instability,
particularly the European model (ecmwf). Stay tuned as we fine tune the details in
the days ahead.

Lingering showers are possible on Friday as the storm system
departs the area to the east. Upper level high pressure will build
in from the west, promising a tranquil next weekend after
(hopefully) the region receives a much needed, appreciable


162135z...coast/valleys...a few patches of low clouds remain at the
immediate coast vcnty ksan. Patches of low clouds may return to the
immediate coast after 03z Sunday, but impacts at coastal taf sites
is unlikely.

Areas of northeast winds 15-25 knots with local gusts to 35 knots
will continue through tonight. Low level wind shear and weak to moderate
up/downdrafts are likely vcnty ksna, kont and ksbd.

Mountains/deserts...sct-bkn high clouds at/above 20,000 ft mean sea level and
unrestricted vis will continue through tonight.


no hazardous marine weather is expected through Tuesday. Stronger
west winds gusting to 20 knots could occur Tuesday night through
Wednesday, along with showers.


Fire weather...
Santa Ana winds have begun with the top wind gust measured today
standing at 48 mph this morning at csu San Bernardino. East to
northeast winds have subsided this afternoon, but will pick back up
again tonight with slightly higher speeds than occurred this
morning. Also, relative humidity will continue a dive this
afternoon with poor overnight recovery. Low relative humidity
will prevail inland with a minimum of near 10 percent on Sunday.
Fuel moisture is at record lows. Given these factors and in
coordination with fire partners and weather forecast office Oxnard, a red flag
warning was issued for areas along the coastal mountain slopes
and through valley corridors below the passes and canyons
effective from 1 am Sunday through 6 am Sunday. Note that this
will not be a widespread wind event, rather the strong winds will
be contained through these wind-prone corridors where east to
northeast winds will blow at 20 to 30 mph with peak gusts to 50

Winds will subside on Monday with wind-prone locations out of the
east to northeast at 15-20 mph with peak gusts to 35 mph before
relaxing during the afternoon. Relative humidity will remain low
at near 10 percent Monday afternoon.

The humidity will increase beginning on Tuesday as winds turn back
onshore ahead of a storm system moving down the coast from the

The storm system from the north will arrive late Tuesday, poised
to bring our first widespread wetting rain of the season! The
brunt of the precipitation will occur Wednesday-Thursday.
There is a large spread of outcomes in relation to the track of
the storm system and precipitation amounts. A solid 0.50-1.00
inches is currently forecast, but note that this could change up
or down drastically, depending on the track of the storm.


Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


Sgx watches/warnings/advisories... flag warning from 1 am to 6 PM PST Sunday for Orange County
inland areas-Riverside County mountains-including the San
Jacinto Ranger district of the San Bernardino National
Forest-San Bernardino County mountains-including the
mountain top and front country Ranger districts of the San
Bernardino National Forest-San Bernardino and Riverside
County valleys -the inland Empire-San Diego County inland
valleys-San Diego County mountains-including the Palomar
and Descanso Ranger districts of the Cleveland National
Forest-San Gorgonio Pass near Banning-Santa Ana Mountains-
including the Trabuco Ranger district of the Cleveland
National Forest.


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