Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 192030
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PDT Fri May 19 2017

.SYNOPSIS...
High pressure building across CA and weak offshore flow will
create widespread above normal high temperatures through
Saturday. Above normal highs will continue for inland areas
through early next week, with gradual cooling the latter half of
next week. A return of a shallow marine layer and weak onshore
flow will create the possibility of low clouds and fog along the
immediate coast Sunday morning, spreading slowly inland next week.

&&

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

At 1 pm PDT, water vapor satellite imagery displayed an upper-
level ridge off of the California coast. Visible satellite showed
clear skies across the region. Surface observations showed east
to northeast wind gusts of mostly 20-25 mph through mountain
passes and along coastal mountain slopes, due to a 1020 mb high
over northeast Utah and a 1011 mb low over extreme southwest
California.

A warming trend will continue across the region through this
weekend as heights aloft increase and offshore flow keeps the
marine layer shallow and offshore. H850 temperatures will increase
to around 25 deg C by Monday, which will help highs in the Low
Deserts increase to the low 100s F Sunday through Tuesday.
Mountain and Valley areas will be warmest Saturday and Sunday,
while Coastal areas will begin to see relief Sunday as the marine
layer slowly redevelops. Only one site is forecast to break a
record high on Saturday and Sunday at this time. Chula Vista`s old
record for Saturday is 79 degrees set back in 1941 and they are
forecast to hit 83. Sunday`s record high for Chula Vista is 76 set
in 2012, and they are forecast to reach 79. Weakening surface
pressure gradients will create onshore westerly winds across the
region by Sunday afternoon. Offshore winds today through Saturday
are expected to remain below Wind Advisory criteria.

Patchy fog and low clouds could return to the coast Sunday
morning, has greater chances Monday morning, and should push into
the valleys by Tuesday morning. Lowering heights and the return of
onshore flow and marine layer will help highs across the region
return to seasonal normals by Wednesday, with slightly below
normal highs expected on Thursday and Friday as upper-level
troughing develops along southwest California.

&&

.AVIATION...
191955Z...P6SM and primarily SKC expected through Saturday morning.
One possible exception is the very slight chance of fog within 3 sm
of the coast 20/0600-1500 UTC.

&&

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

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

PUBLIC...JJT
AVIATION/MARINE...Harrison



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