Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 191701
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1001 AM PDT Mon Jun 19 2017

.SYNOPSIS...
Building high pressure aloft will continue to increase afternoon
temperatures through mid week, creating very hot weather Tuesday
and Wednesday for inland areas. A shallow marine layer will
develop night/morning low clouds and fog along the coast through
the week, and keep high temperatures closer to seasonal normals.
Slightly lower high temperatures for the end of the workweek, then
a slight increase in temperatures again for the weekend.

&&

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

At 9 am PDT, water vapor satellite imagery displayed an upper-
level ridge centered over the AZ/NM border, with south-southeasterly
flow aloft over Southern CA. Visible satellite showed low clouds
over the waters hugging the coast, with a few areas of fog over
the coastal mesas. Surface observations showed temperatures were
around 5 degrees warmer than this time yesterday, and Palm Springs
airport was already at the century mark.

The aforementioned ridge will continue to build over the next few
days. This will continue the warming trend, especially over the
deserts where record-breaking heat is expected. 32-24 deg C H850
temps will yield surface temperatures of...

113-121 deg F in the Coachella Valley and S. D. County Deserts
108-114 deg F in the High Desert
100-110 deg F in the Inland Empire
95-105 deg F in the mountains below 5000 ft
90-103 deg F in the inland valleys

by Tuesday. The Excessive Heat Warnings and Heat Advisories
remain in effect through mid week (See LAXNPWSGX for additional
details). The very hot weather weather will linger Wednesday, then
lowering heights aloft will drop temperatures a few degrees
Thursday and Friday. Unfortunately, models show the ridge
lingering near the region through the weekend, with a slight bump
in high temperatures Saturday through next Monday. Luckily for the
coast, a shallow marine layer will help to moderate temperatures,
keeping highs near seasonal normals through the week.
Night/morning low clouds and fog is expected to continue along the
coast through the week, with lowest visibility expected Tuesday
and Wednesday morning due to the ridge aloft peaking. Slight
deepening will develop by the end of the week as heights aloft
lower.

The position of the high this weekend might be able to pull some
monsoonal moisture into the region. Right now, only one model is
showing precipitation over the mountain ridges, so will keep the
forecast dry for now. However, it will be something to keep an
eye on.

&&

.AVIATION...
191615Z...Coastal airports...SKC-SCT005 today at KSAN, KCRQ and
KSNA. Beaches and coastal waters BKN005-008.

Tuesday 04-10Z...BKN-OVC005-010 moving onshore with CIGS lowering to
OVC002-005 between 10-15Z and vis lowering to between 1/2 and 3
miles in fog. Clouds and fog clearing from coastal airports between
15-16Z Tuesday.

Valleys, Mountains and Deserts: Clear skies and unrestricted
visibility through Wednesday. High density altitude at KPSP and
KTRM with max temperatures between 118-122.

&&

.MARINE...
Areas of late night through mid-morning fog with visibility 1 mile
or less through Thursday. Increasing south swell mixing with the
west swell Tuesday through Thursday.

&&

.BEACHES...
Beach Hazard Statement for strong rips currents in effect through
Thursday. A mix of southerly and westerly swells Tuesday-Thursday
with large tidal swings (high tides 7 ft with low tides -1.0 ft)
will result in strong and dangerous rip currents.

&&

.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 Apple and
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass Near Banning.

     Heat Advisory until 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.

     Heat Advisory until 9 PM PDT Wednesday for Orange County Inland
     Areas-San Diego County Valleys-Santa Ana Mountains and
     Foothills.

PZ...NONE.
&&

$$

PUBLIC...JJT
AVIATION/MARINE/BEACHES...Moede



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