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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

                            
020 
FXUS66 KSGX 212032
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PDT Thu Jun 21 2018

.SYNOPSIS...
High pressure aloft will bring hot weather to the deserts this 
afternoon through Friday, but onshore flow and a strong marine layer 
will continue the mild weather along the coast with extensive night 
and morning low clouds and only partial afternoon beach clearing. 
High pressure will weaken over the weekend and bring cooler weather 
to inland areas. Fair weather will continue early next week with 
temperatures increasing slightly, but night and morning low clouds 
will continue near the coast.

&&

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

Stratus cleared to near the beaches, with widespread stratus from 
the beaches west a few hundred miles off the coast. Temperatures had 
exceeded 100 in the deserts, with some areas likely reaching 110 by 
late afternoon, but the marine layer, with an early morning 14 deg C 
inversion, kept the coast much cooler, with areas near the beaches 
only in the mid to upper 60s. A weak coastal eddy was also occurring.

High pressure aloft is centered over NW Sonora, and a roughly east-
west ridge of high pressure will continue this afternoon and then 
shift a little bit south farther into Mexico Friday and Saturday as 
troughing developing to the north. While heights fall slightly 
Friday, 850 MB temps peak then, so most of the deserts, especially 
the lower deserts, will have their hottest day Friday. The lower 
deserts should be mostly around 110 or slightly higher today and 112-
115 Friday. The high deserts will be 102-108. An upper low moving 
through Idaho/northern Nevada/northern Utah Saturday will bring weak 
cyclonic flow aloft here, versus the previous anti-cyclonic flow and 
also force the high to be farther south and also farther west over 
the ocean. It will end up being 5-8 deg F cooler over inland areas 
Saturday, with little change Sunday. While clouds will likely linger 
along the coast today/Friday, the cooling aloft should result in 
better afternoon clearing over the weekend. Some warming could 
return early next week as the high aloft gradually expands, 
extending all the way from the Central Pacific to Texas. Monsoonal 
moisture should stay well to the southeast, so no precipitation is 
expected through late next week except for very minor drizzle from 
the marine layer at times.

&&

.AVIATION... 
211930Z...Coast/Valleys...BKN-OVC008-012 Tops 2200 ft at the coast 
this afternoon spreading 20-25 miles inland tonight and reaching 
KONT and KRAL between 12-16Z Friday where vis will be 3 SM in FG/HZ. 
The low clouds will clear from the inland valleys by late morning, 
with afternoon clearing reaching KSAN, KCRQ, KSNA between 19-22Z. 

Mountains/Deserts...Mostly clear with unrestricted VIS through 
Friday. 

&&

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

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning from 11 AM this morning to 8 PM PDT 
     Friday for Apple and Lucerne Valleys-Coachella Valley-San 
     Diego County Deserts-San Gorgonio Pass Near Banning.

PZ...NONE.

&&

$$

PUBLIC...Maxwwell
AVIATION/MARINE...Moede


000
FXUS66 KSGX 212032
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PDT Thu Jun 21 2018

.SYNOPSIS...
High pressure aloft will bring hot weather to the deserts this 
afternoon through Friday, but onshore flow and a strong marine layer 
will continue the mild weather along the coast with extensive night 
and morning low clouds and only partial afternoon beach clearing. 
High pressure will weaken over the weekend and bring cooler weather 
to inland areas. Fair weather will continue early next week with 
temperatures increasing slightly, but night and morning low clouds 
will continue near the coast.

&&

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

Stratus cleared to near the beaches, with widespread stratus from 
the beaches west a few hundred miles off the coast. Temperatures had 
exceeded 100 in the deserts, with some areas likely reaching 110 by 
late afternoon, but the marine layer, with an early morning 14 deg C 
inversion, kept the coast much cooler, with areas near the beaches 
only in the mid to upper 60s. A weak coastal eddy was also occurring.

High pressure aloft is centered over NW Sonora, and a roughly east-
west ridge of high pressure will continue this afternoon and then 
shift a little bit south farther into Mexico Friday and Saturday as 
troughing developing to the north. While heights fall slightly 
Friday, 850 MB temps peak then, so most of the deserts, especially 
the lower deserts, will have their hottest day Friday. The lower 
deserts should be mostly around 110 or slightly higher today and 112-
115 Friday. The high deserts will be 102-108. An upper low moving 
through Idaho/northern Nevada/northern Utah Saturday will bring weak 
cyclonic flow aloft here, versus the previous anti-cyclonic flow and 
also force the high to be farther south and also farther west over 
the ocean. It will end up being 5-8 deg F cooler over inland areas 
Saturday, with little change Sunday. While clouds will likely linger 
along the coast today/Friday, the cooling aloft should result in 
better afternoon clearing over the weekend. Some warming could 
return early next week as the high aloft gradually expands, 
extending all the way from the Central Pacific to Texas. Monsoonal 
moisture should stay well to the southeast, so no precipitation is 
expected through late next week except for very minor drizzle from 
the marine layer at times.

&&

.AVIATION... 
211930Z...Coast/Valleys...BKN-OVC008-012 Tops 2200 ft at the coast 
this afternoon spreading 20-25 miles inland tonight and reaching 
KONT and KRAL between 12-16Z Friday where vis will be 3 SM in FG/HZ. 
The low clouds will clear from the inland valleys by late morning, 
with afternoon clearing reaching KSAN, KCRQ, KSNA between 19-22Z. 

Mountains/Deserts...Mostly clear with unrestricted VIS through 
Friday. 

&&

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

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning from 11 AM this morning to 8 PM PDT 
     Friday for Apple and Lucerne Valleys-Coachella Valley-San 
     Diego County Deserts-San Gorgonio Pass Near Banning.

PZ...NONE.

&&

$$

PUBLIC...Maxwwell
AVIATION/MARINE...Moede