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Area Forecast Discussion (AFD)

Issued by San Diego, CA (SGX)

FXUS66 KSGX 170416 AAA

Area Forecast Discussion
National Weather Service San Diego CA
915 PM PDT Tue Jul 16 2019

Upper-level low pressure moving into the region will create a
deeper marine layer and cooler weather across the area through
Saturday. High pressure building to the east early next week will
create near normal high temperatures by Tuesday. A gradual influx
of monsoonal moisture will create a slight chance of afternoon 
thunderstorms near the mountains on Tuesday.



Evening Update:

Stronger pressure gradients this evening running up to 8 mb from the 
coast to the lower deserts. The marine layer is stronger and coastal 
stratus is already pushing onshore. The threat of dense fog 
continues to look less than last night. The forecast is on track and 
no updates were made this evening.

Previous Discussion, issued at 151 PM PDT:

At 1 PM, water vapor satellite imagery displayed an upper-level 
ridge centered around the AZ/NM/Mexico border, and an upper-level 
trough moving into central CA. A coastal eddy was helping to keep
stratus along portions of the coast this afternoon.

Ensembles are in good agreement with the trough moving across CA
through Wednesday, and southwest flow aloft lingering over the
region through Saturday. This will create a deeper marine layer,
developing night/morning low clouds and fog further inland into
the valleys and cooler weather across the region. Highs today will
be between 5 degrees below normal to 5 degrees above normal, then
most areas will be just below normal Wednesday, then highs will be
from 5 to 15 degrees below normal Thursday through Saturday.

Ensemble solutions become a bit scattered for the overall pattern
early next week, however confidence is moderate to high that a
ridge will strengthen over the Four Corners region. This will help
increase our high temperatures to mostly near normal by Tuesday.
Monsoonal moisture will start to move into the region, with
a slight chance of thunderstorms possible over the mountains Tuesday
afternoon. Night/morning low clouds will be more restricted to 
coastal areas through the period.


170355Z...Coast/Valleys...Stratus with bases 600-1200 ft MSL will 
spread 15-20 sm inland overnight. Areas of vis 3-5 SM developing on 
the coastal mesas and higher coastal terrain after 08Z. Stratus 
clearing inland 15-17Z and near the coast 17-19Z, though beaches 
will remain mostly BKN-OVC through the afternoon. Low clouds will 
move back inland after 18/00Z with bases 900-1500 ft MSL.

Mountains/Deserts...Mostly clear with unrestricted vis through 
Wednesday evening.


No hazardous marine weather is expected through Sunday.


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