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Area forecast discussion
National Weather Service San Diego California
400 PM PST sun Dec 10 2017

Quick update...
have increased cloud cover even more to account for the thick high
clouds that are streaming in associated with the cutoff low off
baja. Mostly cloudy skies will persist through Monday morning then
gradual clearing Monday afternoon through Monday evening. No other
changes at this time.

&&

Synopsis...
the Santa Ana winds will gradually weakening this afternoon and
tonight, but humidity will continue to be very low. Dry east
to northeast winds will continue in most areas this week, with
locally gusty winds at times below passes, canyons and mountain
crests. Temperatures will be well above normal, though with a slight
cooling trend the second half of this week. No precipitation is
expected this week and likely much of next week. However, occasional
high clouds will drift over, especially through Monday.

&&

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

Local gusty winds were continuing in the mountains and western
foothills, especially in San Diego County. Local gusts were still 50-
60 mph, but these will decrease in the next few hours. Temperatures
were mostly in the upper 70s and 80s at lower elevations, with
highest temps in Orange County, where one mesonet site near Laguna
Beach was 90, and Huntington Beach reported 89. High clouds were
rather thick in San Diego County, and that combined with some
lingering wind will result in another mild night, though some low-
lying locations will still have lows in the 40s, especially north of
San Diego County.

Winds decrease rapidly tonight in response to much weaker
temperature and height gradients, especially at 850 mb. Only local
gusty winds will occur Monday morning, mainly below Cajon Pass and
just downwind from mountain crests, with most gusts under 35 miles per hour.
Overall, with the West Coast ridge combined with the eastern North
American trough and surface high pressure over the Great Basin, we
will continue to have above normal temps, mostly 75-85 for highs,
through Wed or Thu, then decreasing slightly due to some shortwaves
moving through the West Coast. Winds might increase slightly Tuesday
with a weak upper low to our south, but later in the week, the winds
will be relatively weak. Humidity will remain quite low, except
during sea breezes near the immediate coast, and no marine layer
will be present over the coastal waters. While the upper ridge looks
weaker from next weekend into early next week, there is no
indication of any system producing precipitation here for at least
10 days, probably longer.

&&

Aviation...
102115z...NE to east winds 20-30 kt with gusts to 50 kt in the wind
prone passes and canyons and on the coastal mountain slopes and
foothills will create strong uddfs/low level wind shear over and west or SW of the
mountains through about 11/00z. Winds will decrease tonight, but
remain gusty from the NE-east 15 to 25 kts with locally higher
gusts along the coastal foothills into Monday. Otherwise, broken clouds
at or above fl200 and unrestricted vis through Mon morning.

&&

Marine...
no hazardous marine weather is expected through Thursday.

&&

Fire weather...
very low humidity will continue this week, with inland areas having
5 to 10 percent minimums each day and poor nocturnal recoveries.
Humidity at the coast will be somewhat more variable due to
occasional sea breezes. The stronger easterly flow this afternoon
with areas of 20-30 miles per hour winds and local gusts to 60 miles per hour will weaken
tonight. Only local winds 15-25 miles per hour with gusts to near 35 miles per hour will
occur Monday, with durations of these winds less than 6 hours. A
slight increase in wind is possible Tuesday before winds decrease
again the second half of the week. There could be slight
improvements in the relative humidity late in the week, but with
values still below normal. Fire weather hazards will be critical
today but then just elevated Monday through next weekend.
The red flag warning will be allowed to expire at 8 PM tonight.

&&

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

&&

Sgx watches/warnings/advisories...
California...High Wind Warning until 4 PM PST this afternoon for San Diego
County mountains-San Diego County valleys.

Red flag warning until 8 PM PST this evening 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 coastal
areas-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.

Pz...none.

&&

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