Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 081756
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
930 AM PST Fri Dec 8 2017

.SYNOPSIS...
Northeasterly winds will be not be as strong today but low humidity
will continue to prevail. Areas of smoke will occur mainly near the
coast, partly due to a sea breeze bringing smoke currently over the
coastal waters back onto land. Winds will increase again Saturday
and peak Sunday due to more strengthening of the high pressure
system over the Great Basin, though they will not be as strong as
winds from Thursday. Overall, a strong ridge of high pressure will
keep skies mostly clear through next week with low humidity and
occasional east to northeast winds.

&&

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

Skies were mostly sunny this morning, except for areas of smoke near
and downwind from fires. Winds were somewhat lighter at mid-morning,
with gusts 40-45 MPH at windier locations mainly near and just west
of mountain crests and a recent gust of 46 MPH near Descanso. HRRR
and local WRF show a well-defined sea breeze this afternoon in
western San Diego County and parts of Orange County but mostly not
making it into the Inland Empire. A consequence of the sea breeze is
that it, based on HRRR Smoke output, will bring in smoke from the
coastal waters, most of which originated with fires in LA/Ventura
Counties. High temperatures this afternoon will be in the mid 70s to
lower 80s at lower elevations, locally higher.

A strong ridge of high pressure was aligned north-south along the
West Coast, with a deep trough of low pressure from the Great Lakes
to Texas. Only minor changes in the position of the high will occur
for the next week though winds will vary based on other factors,
including the surface pressure gradients, winds aloft and upper lows
periodically to our south. Surface winds will increase Saturday,
peaking Sunday as the mountain crest inversion strengthens again,
even though only moderate increases in the MSLP gradients will
occur. Local WRF shows gust potential around 50-55 MPH Saturday and
55-65 MPH Sunday mainly in San Diego County in the mountains and
western foothills. Easterly winds will likely reach parts of the
coast Sunday, especially in northern San Diego County. The high wind
warning may need to be extended for some locations beyond 4 PM today.

Winds will decrease quite a bit Sunday night and Monday, though
offshore flow will continue in most areas most of next week. There
could be sea breezes near the coast at times in the afternoons. Some
model runs have shown increases in the offshore flow again around
Thursday or Friday. Overall, temperatures will be above normal,
especially daytime temperatures with highs generally in the upper
70s to lower 80s through next week. Due to low humidities, wind
sheltered locations will be cool at night, with mostly 30s and 40s
except 50s where winds are more persistent and a few places along
the immediate coast.

&&

.AVIATION...
081605Z...NE to E winds 20-30 kt with gusts to 40 kt in the wind
prone passes and canyons and on the coastal mountain slopes and
foothills will create MOD-STG UDDFS/LLWS over and W or SW of the
mountains through Saturday morning. Strong surface winds at KONT,
KSNA, KCRQ and KSAN not expected. Otherwise gradually increasing
clouds AOA 20000 ft MSL and P6SM vis through Saturday morning.

&&

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


&&

.FIRE WEATHER...
Critical fire conditions will continue in many areas through Sunday.
Locally gusty winds will occur today mainly in the mountains and
foothills with 15-30 MPH sustained winds with gusts 40-55 MPH.
However, west of the mountains, winds will be lighter, with a sea
breeze reaching coastal and valley areas of San Diego County and
most of Orange County this afternoon, with winds mostly 8-12 MPH and
gusts to 20 MPH. Minimum humidities will mostly be at/below 10% in
many inland areas today, with only minor increases in sea breeze
locations.

Offshore flow will increase again Saturday and peak Sunday morning
with winds generally 20-35 MPH with gusts 45-65 MPH and minimum
humidities locally 5% or less. Winds will decrease substantially
late Sunday/Sunday night.

The Red Flag Warning remains in effect until 8 pm Sunday for most
areas, except coastal Orange County where it expires at 8 pm
Saturday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning until 4 PM PST this afternoon for Riverside
     County Mountains-San Bernardino County Mountains-San
     Bernardino and Riverside County Valleys-The Inland Empire-
     San Diego County Mountains-San Diego County Valleys-San
     Gorgonio Pass Near Banning-Santa Ana Mountains and
     Foothills.

     Red Flag Warning until 8 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 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.

     Red Flag Warning until 8 PM PST Saturday for Orange County
     Coastal Areas.

PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...Maxwell
AVIATION/MARINE...Harrison



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