Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 272048
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
148 PM PDT Thu Jul 27 2017

.SYNOPSIS...
Seasonal summer weather through Friday with high pressure over the
Southwest. Weak monsoonal flow returns over the weekend with
isolated thunderstorms over the mountains and deserts Saturday and
Sunday. The monsoonal pattern strengthens Monday and Tuesday with
greater thunderstorm coverage over the mountains. Some
thunderstorms may drift west of the mountains into the valleys.

&&

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

For mid summer today is shaping up to be near normal for most
areas. The marine layer is pretty strong for this time of the year
but the much lower atmospheric moisture has helped to burn off
the morning clouds quicker than previous days. With the relatively
strong marine layer in place morning clouds will slow heating
near the coast Friday morning, but clearing will affect all areas
by late morning. Temperatures Friday will be similar to today.

A gradual return to a SE monsoonal flow pattern will setup this
weekend. On Saturday there will be a slight chance for mountain
thunderstorms in the afternoon and evening and with dry lower
levels there will be a slight risk for dry lightning strikes.
Sunday through next week will see gradual increase in atmospheric
moisture due to persistent SE flow in our region. Monday and
Tuesday may see the highest relative coverage of convection,
possibly affecting areas west of the mountains too, due to a
couple of weak easterly waves moving through the flow regime.
Flash flood risk will also be relatively the highest at that time
due to potentially better thunderstorm organization.

The moist SE monsoonal pattern will generally continue through
next week. Deep tropical moisture will remain well to the south as
the hurricane activity moves west over the open Pacific Ocean.

The medium range models are suggesting that a strong upper level
high will shift north across Central and Northern Nevada towards
the end of next week. The GFS is more aggressive strengthening the
high to 600 DM during the period which could bring a very hot
pattern to the deserts, with the most abnormally hot weather north
of our area...but continued above normal for Southern California
as well.

&&

.AVIATION...
272021Z...Coasts/Valleys...Through 28/0000 UTC, P6SM vis and mostly
SKC except for possibly some lingering SCT-BKN clouds 1500-2000 ft
msl within 3 sm of the coast. 28/0000-1400 UTC, stratus re-
developing and moving 15-20 sm inland, with bases around 1200-1600
ft msl, tops around 1800-2000 ft msl and local vis 3-5 sm.
Confidence in stratus/fog reaching KONT is low. Forecast marine
layer inversion strength of 10 deg C at 28/1200 UTC. Clearing of
stratus likely during the 28/1500-1800 UTC time-frame. For valley
locations beyond 20 sm inland, P6SM vis and mostly SKC will likely
continue through Friday morning.

Mountains/Deserts...P6SM vis and mostly SKC through Friday morning.

&&

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


&&

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


&&

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

PZ...NONE.
&&

$$

PUBLIC...Brotherton
AVIATION/MARINE...Harrison



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