Area Forecast Discussion
Issued by NWS San Diego, CA

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930
FXUS66 KSGX 271023
AFDSGX

AREA FORECAST DISCUSSION
National Weather Service San Diego CA
323 AM PDT WED JUL 27 2016

.SYNOPSIS...
Hot and dry weather will continue through Thursday. Slightly
cooler over the weekend as moisture in monsoonal flow from the
southeast brings more clouds and a chance of showers and
thunderstorms, mainly in the mountains and deserts. The cooler
conditions should persist into next week as a weak trough develops
along the West Coast.

&&

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

The main story for the next several days will be the hot weather
and then chances for mountain and desert thunderstorms over the
weekend and into early next week.

Weak onshore flow was noted early this morning with some scattered
coastal stratus offshore and along the SoCal coast. A rather
strong upper high was centered over Central Nevada this morning
and is forecast to strengthen to about 597 DM through Thursday and
shift a bit southeast as well. The high should cause our desert
areas to warmup a few degrees further compared to Tuesday`s highs
which were already near heat advisory levels. Therefore have
issued a heat advisory for the High Deserts, Coachella Valley,
and Anza Borrego Desert through Thursday. Temperatures in those
areas will be 5 to 10 degrees above normal.

A weak upper level trough will approach from the NW this weekend,
and the subtropical high pres ridge will weaken and shift further
east. Onshore flow will also increase a bit, and a SE flow aloft
will also develop due to the repositioning of the high.
Temperatures will cool down to near normal or even a few degrees
below normal for this weekend, along with an influx of
subtropical moisture from the SE. Enough moisture and instability
should help to kick off scattered diurnal convection in the
mountains and deserts beginning Friday, and continuing into early
next week. Initially, there will be a risk of dry lightning as the
lower levels will be slow to moisten up. Then by Sunday and
Monday, there will be a threat of heavy rainfall, as an influx of
deeper moisture with PWATS over 1.5" moves, into the region from
the SE.

It looks like convection chances should decrease by the middle of
next week as another weak upper level trough moves in from the NW
and helps to shift the monsoonal moisture to the east of the
region.

&&

.AVIATION...
270940Z...Coasts...Patchy stratus with bases 800-1100 ft MSL will
slowly develop along the San Diego County coast and up to 10 mi
inland through the morning. Only a small chance of a cig at KSNA
between 12-15Z. Local vis 3-5 SM in BR possible where stratus nears
higher coastal terrain. Clouds and vis restrictions clearing by 16Z.
Patchy stratus will redevelop along the coast after 28/07Z. Bases
will be around 900-1300 ft MSL.

Valleys/Mountains/Deserts...Cumulus clouds will develop over the
mountain crests late this morning and dissipate shortly after
sunset. Otherwise a few clouds at/above 15000 ft MSL and
unrestricted vis through Thu morning.

&&

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


&&

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


&&

.SGX Watches/Warnings/Advisories...
CA...Heat Advisory from 10 AM this morning to 8 PM PDT Thursday for
     Apple and Lucerne Valleys-Coachella Valley-San Diego County
     Deserts.

PZ...None.
&&

$$

PUBLIC...Brotherton
AVIATION/MARINE...SS



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