National Weather Service Forecast Discussion

Dicussion provided by the National Weather Service Forecast Office located in San Diego, California

000
FXUS66 KSGX 231631
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
931 AM PDT Mon Oct 23 2017

.SYNOPSIS...
High pressure aloft and surface high pressure over the Great Basin
will create gusty Santa Ana winds and hot weather into Tuesday.
Winds and high temperatures will begin to lower on Wednesday, with
above normal highs expected into early next week. Low clouds and
fog will return to the coast this weekend.

&&

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

Hot and very dry weather will start off the work week with upper-
level ridging aloft, and surface high pressure over the Great
Basin. H500 heights will peak around 595 DM today and tomorrow
over southwest CA. This will create high temperatures around 10
deg above normal for desert and mountain locations. The
downsloping winds west of the mountains will help create highs 15
to 25 deg above normal for coastal and valley locations today and
Tuesday. Several high temperatures records are expected to be
broken or tied over the next few days. Please see our weather
story on our webpage for the specific temperatures and record
information. An Excessive Heat Warning will continue for the
Coasts and Valleys through Tuesday for highs in the low 100s
inland, and the mid-80s to mid-90s at the beach.

Gusty Northeasterly winds will continue through Wednesday
afternoon in the mountains, valleys and over most of Orange
County. Sustained winds of 15-30 mph with gusts of 40-60 mph are
possible through the period, with strongest winds developing
Tuesday morning though mountain passes and along coastal mountain
slopes. A Wind Advisory remains in effect through the period.
A Red Flag Warning also remains in effect through Wednesday
evening for extremely low relative humidity in the single digits,
gusty Northeasterly winds and hot weather.

The ridge aloft will weaken through the end of the week, but
remain over the region. High temperatures will lower to just above
seasonal normals by Saturday. Returning onshore flow will
increase humidity across the coast and valleys by the end of the
week, and also create the possibility of low clouds and fog along
the immediate coast.

&&

.AVIATION...
231600Z...Clear with unrestricted vis through Tuesday. Areas of
northeast winds 15-25 kt and gusts 35-45 kt will occur at times,
strongest Tuesday morning. Strongest winds will be through and below
the passes and canyons, on coastal mountain slopes and foothills,
and locally extending into coastal areas. This will produce MDT-STG
UDDFS and LLWS over and W/SW of the mountains. This will impact
vcnty KONT, KSBD, KRAL and KSNA at times. Surface northeast winds
will be most likely at those airports Tuesday morning.

&&

.MARINE...
No hazardous marine weather is expected through Friday.

&&

.BEACHES...
A combination of west-northwest and south swells will bring mostly 3-
5 foot surf at the beaches of Orange County and San Diego County
through Wednesday, along with a high rip current risk.

&&

.FIRE WEATHER...
High pressure aloft and surface offshore flow will create critical
fire weather conditions for areas over and west of the mountains
through Wednesday. Northeasterly wind gusts of 40-60 mph are
possible for portions of the mountains, valleys and areas of
Orange County, with strongest winds occurring Tuesday morning
along coastal mountain slopes. Minimum relative humidity will be
in the single digits for most areas, with poor overnight recovery.
High temperatures will range from 10-25 deg above normal, as well.
A Red Flag Warning remains in effect through Wednesday Evening.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 6 PM PDT Wednesday 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 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.

     Wind Advisory until 2 PM PDT Wednesday for Orange County Coastal
     Areas-Orange County Inland Areas-Riverside County Mountains-
     San Bernardino County Mountains-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Mountains-San Diego County Valleys-Santa Ana Mountains and
     Foothills.

     Excessive Heat Warning until 8 PM PDT Tuesday 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.

PZ...NONE.
&&

$$

PUBLIC/FIRE...JJT
AVIATION/MARINE/BEACHES...Maxwell

NWS SGX Office Area Forecast Discussion