000
FXUS66 KSGX 211017
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
317 AM PDT Sat Oct 21 2017

.SYNOPSIS...
High pressure aloft and surface high pressure over the Great Basin
will bring areas of gusty northeast to east winds...especially
below passes and canyons...very low humidity...and hot weather
this weekend through Tuesday. The most extreme combination of low
humidity... stronger and more widespread winds...and heat is
expected on Monday and Tuesday. Winds will weaken Wednesday with
cooling spreading inland for Wednesday into next weekend.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

High pressure aloft off the Baja coast will expand northward into
California and strengthen through Tuesday. Surface high pressure
over the Great Basin will bring locally gusty northeast winds near
the coastal foothills and below passes and canyons today and
Sunday...with more widespread and stronger winds for Monday and
Tuesday. This will bring a strong warming trend through Monday.
Monday and Tuesday are expected to the hottest days for coastal
and valley areas with highs temperatures mostly in the
90s...except 98 to 106 for inland Orange County into the western
Inland Empire and for the mesas to the western valleys in San
Diego County. The beaches will not be quite as hot with high
temperatures mostly in the 80s. Temperatures may not fall below
the 70s Monday night in some of the windier coastal foothill
locations.

High pressure aloft will begin move westward to a position off the
California coast beginning Wednesday with a trough of low pressure
developing over the interior western states for the latter half of
the week. A cooling trend is expected to develop on Wednesday and
extend into Friday and Saturday. The GFS and Canadian models are
faster to move this trough of low pressure into the plains on
Friday and Saturday with the ECMWF slower and more amplified over
the Great Basin and southwest states on Friday before moving it
slowly eastward on Saturday. With these scenarios...the cooling
would be less with the GFS and greater for the ECMWF.

&&

.AVIATION...
210945Z...Coast/Valleys...Areas of low clouds will persist this
morning, with bases 2500-4000 ft MSL and tops to 5000 ft MSL. TAF
sites could be impacted at times through 18Z, but timing is
uncertain. Aft 18Z, mostly clear with unrestricted vis. Gusty
northeast winds will develop after 12Z and could impact KSNA, KONT
and KSBD through this afternoon.

Mountain/Deserts... Strong and gusty northeast winds develop this
afternoon. Winds of 15-30 kt with gusts to 35-45 kt will produce
mdt up/downdrafts and LLWS over and west of the mtns.

&&

.MARINE...
Winds and waves continue to subside this morning. Lighter winds and
calmer seas are expected through next week.

&&

.BEACHES...
A short-period northwest swell from 290 degrees and a long-period
northwest swell from 295 degrees will build through Saturday. This
will bring another round of elevated surf from 3-6 ft and an
increased rip current threat. Although surf lowers somewhat on
Sunday, rip currents will still be a concern. A Beach Hazards
Statement is in effect through Sunday afternoon.
&&

.FIRE WEATHER...
High pressure aloft and surface high pressure over the Great Basin
will bring areas of gusty northeast to east winds...especially
below passes and canyons...very low humidity...and hot weather
for this weekend through Tuesday. The most extreme combination of
low humidity... stronger and more widespread winds...and heat is
expected on Monday and Tuesday. Winds will begin in the San
Bernardino County Mountains...the Inland Empire and Santa Ana
Mountains this morning...then increase in coverage toward the
coast and spread into San Diego County Sunday through Tuesday.
Strongest winds will be during the mornings Monday and Tuesday.

Lowest daytime humidity of 10 to 15 percent today...5 to 10
percent Sunday...and around 5 percent Monday and Tuesday with
poorest overnight recovery in the windier areas near the coastal
foothills. For today and Sunday areas of northeast winds 15 to 25
mph with gusts to 35 near the coastal foothills and below passes
and canyons. Stronger and more widespread winds for Monday and
Tuesday with areas of northeast winds 20 to 30 mph with gusts to
45 mph. Isolated gusts to 50 mph.

Winds should weaken Wednesday with some cooling and recovery of
humidity with cooling and higher humidity spreading inland for the
latter half of the week.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Fire Weather Watch from Sunday morning through Tuesday afternoon
     for Orange County Coastal Areas-Orange County Inland Areas-
     Riverside County Mountains-Including The San Jacinto Ranger
     District Of The San Bernardino National Forest-San Diego
     County Inland Valleys-San Diego County Mountains-Including
     The Palomar And Descanso Ranger Districts of the Cleveland
     National Forest.

     Red Flag Warning from 10 AM this morning to 6 PM PDT Tuesday for
     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-Santa Ana Mountains-Including The
     Trabuco Ranger District of the Cleveland National Forest.

     Excessive Heat Watch from Monday morning through Tuesday evening
     for Orange County Coastal Areas-Orange County Inland Areas-
     San Bernardino and Riverside County Valleys-The Inland
     Empire-San Diego County Coastal Areas-San Diego County
     Valleys.

     Beach Hazards Statement through Sunday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...Small Craft Advisory until 4 AM PDT early this morning for
     Coastal Waters from San Mateo Point to the Mexican Border
     and out to 30 nm-Waters from San Mateo point to the Mexican
     Border Extending 30 to 60 nm out including San Clemente
     Island.

&&

$$

PUBLIC/FIRE WEATHER...17
AVIATION/MARINE/BEACHES...PG