Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 171033
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
333 AM PDT Sat Jun 17 2017

.SYNOPSIS...
High pressure aloft over the southwest states will bring well
above average high temperatures into next week...peaking Tuesday
and Wednesday. A shallow marine layer and weak onshore flow will
moderate the heat towards the coast with areas of night and
morning coastal low clouds and and patchy dense fog spreading
locally inland at times. High pressure may weaken slightly the
latter part of next week with cooling spreading into the valleys
Thursday...and slight cooling farther inland on Friday.

&&

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

High pressure aloft over the southwest states will gradually
strengthen the next few days...reaching peak intensity around
Tuesday while centered over Arizona. Slow weakening of the high
pressure is expected for Wednesday and Thursday continuing into
Friday.

High temperatures today and Sunday may warm slightly for inland
areas...with a little greater warming on Monday...with Tuesday and
Wednesday expected to be the hottest days with high temperatures
10 to 15 degrees above average from the inland valleys
inland...and 5 to 10 degrees above average towards the coast. This
will push high temperatures in the lower deserts to around
120...in the upper deserts to near 110...and in the Inland Empire
to the upper 90s to around 110. The excessive heat warning for
the deserts has been extended through Thursday of next week. Even
with slight cooling...high temperatures for Thursday of next week
are expected to be similar to those of this weekend. The marine
layer and weak onshore flow will keep areas towards to the coast
cooler...but with high temperatures still above average.

Satellite imagery early this morning shows an extensive stratus
field off the Baja coast spreading northward along the coast into
Santa Barbara County with a coastal eddy evident. The marine layer
is near 1000 to 1200 feet deep...near to slightly deeper than 24
hours ago with stratus coverage more extensive. The stratus
extends into the far western valleys in San Diego County with
patchy dense fog near the mesas. Not much change is expected for
tonight into Sunday morning...with the marine layer becoming a
little shallower for Monday through Wednesday and stratus coverage
a little patchier. Stratus coverage may increase some the latter
part of next week as onshore flow increases.

&&

.AVIATION...
170830Z...Areas of low clouds and fog at the coast through 16Z
Saturday. Expect bases around 400 feet msl with vis 3-5sm, locally
as low as zero on coastal mesas. Elsewhere, clear skies with
unrestricted visibility through this evening.

&&

.MARINE...
Areas of fog with local visibilities 1 NM or less, mainly during the
late nights and mornings into early next week. Otherwise, no
hazardous marine weather is anticipated through Wednesday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 9 PM PDT Thursday for Coachella
     Valley-San Diego County Deserts-San Gorgonio Pass Near
     Banning.

     Heat Advisory from 11 AM this morning to 9 PM PDT Wednesday for
     Riverside County Mountains-San Bernardino County Mountains-
     San Bernardino and Riverside County Valleys-The Inland
     Empire-San Diego County Mountains.

     Excessive Heat Warning from 11 AM this morning to 9 PM PDT
     Thursday for Apple and Lucerne Valleys.

     Heat Advisory from 11 AM Monday to 9 PM PDT Wednesday for Orange
     County Inland Areas-San Diego County Valleys-Santa Ana
     Mountains and Foothills.

PZ...NONE.

&&

$$

PUBLIC...17
AVIATION/MARINE...PG



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