Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 260354
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
854 PM PDT Sun Aug 25 2019

.SYNOPSIS...
High pressure aloft will keep the weather warm to hot this week with
temperatures near, to a little above already warm mid-summer
averages. The marine layer should slowly rebuild over coastal areas
into midweek, accompanied by a return of some low clouds and fog
nights and mornings. Moisture in easterly flow aloft will decrease,
eclipsing any chance for afternoon thunderstorms after Monday.

&&

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

Satellite imagery at sunset had the remnant low center of IVO about
450 miles south of San Diego. A sheet of thick mid-high clouds was
spreading far in advance of the sfc circulation, over the CA Bight.
Low marine clouds were far offshore and up the Central Coast. Our
00Z Miramar sounding had no marine inversion. Winds below 4K FT had
turned SW-W, but remained easterly 10-15 KTS above to about 15K FT.
PW had increased, mainly in the mid-levels and and stood at 1.44",
but the sounding profile had become more stable compared to 12Z. A
couple of thunderstorms popped over the Riverside Mts and south of
the border this afternoon, but they were remote and no significant
rain was reported.

The proximity of the remnant low off the Baja coast will continue to
influence our weather across SoCal with abundant high clouds,
elevated dewpoints and a warmer night. A weak onshore flow currently
in place, is forecast to persist through the night. Models take the
remnants of Ivo off to the west of us through tomorrow, so at some
point typical thermal influences will prevail with the sea breeze
strengthening and helping to rebuild a shallow marine layer into
coastal areas. The sea breeze may be delayed on Monday, which could
allow temps to rise rapidly west of the mts, but confidence is low.
Temps have been modified and generally increased to follow the ECM
Ensemble mean Mos Guidance this week. Convective chances for Mon
look smaller than today. A Zone Fcst update has been issued.

From previous forecast...

Some night and morning low clouds are still expected at times near
the coastline. Coachella Valley high temperatures should be
moderated, at least for a few days, by a surge of cooler, low level
moist air surging in from the gulf of California.

Generally ensemble data and local WRF shows very little day to day
change in the upper level pattern and in the mid-upper level
moisture for a week or more into the future starting Monday,
including limited if any convection

Some remnant mid level moisture from decaying Tropical Storm Ivo
will be around for the next couple of days  but only interesting
looking mid and high clouds for the rest of the area for most areas,
and maybe some unusual temperature fluctuations.

Temperatures could  peak in the lower deserts and The Coachella
Valley around 109-113 degrees midweek or so, dependent on whether
the low level moisture hangs around there or not.

The upper high will be centered near SoCal late in the week,
although this does not seem to be intense enough for heat products
at this time, especially with some remnant moisture likely to linger
over the area, but the position of the high raises concerns for both
valleys and desert areas on the hottest days.

&&

.AVIATION...
260400Z...Coast/Valleys...Mostly BKN clouds will prevail at/above
15000 ft MSL through Monday, decreasing Monday evening. Local
stratus/fog is possible near the coast 09Z-16Z Mon with bases likely
below 800 ft MSL and vis below 3 miles, but confidence is low.
Otherwise, vis will remain unrestricted through Monday evening.

Mountains/Deserts...Mostly BKN clouds will prevail at/above 15000 ft
MSL through Monday, decreasing Monday evening. Some cumulus with
bases around 8000 ft MSL will develop Monday afternoon over the
mountains. Vis will remain unrestricted through Monday evening.

&&

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

&&

.BEACHES...
South-southeast swells from 160-170 degrees with a 12-13 second
period, generated by the former Tropical Storm Ivo, will generate
elevated surf through Monday morning. Isolated surf up to 6 ft is
possible on the south facing beaches of Orange County. Main impacts
on west facing beaches will be longshore currents. A Beach Hazards
Statement remains in effect for Orange and San Diego county beaches
through Monday morning.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Monday morning for Orange
     County Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.
&&

$$

PUBLIC...10/SMALL
AVIATION/MARINE/BEACHES...Maxwell


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