National Weather Service Forecast Discussion

Dicussion provided by the National Weather Service Forecast Office located in San Diego, California

000
FXUS66 KSGX 222000
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
100 PM PDT Mon Apr 22 2019

.SYNOPSIS...
Low pressure will drop south over Southern California tonight,
bringing partly cloudy skies, along with a chance of showers and
even an isolated thunderstorm or two, mainly over the mountains this
afternoon and evening. Some weak offshore breezes will develop
through and below passes and canyons as flow turns offshore on
Tuesday, bringing drying and warming inland. High pressure aloft
will continue the warming inland this week, but a shallow marine
layer will keep the Coast cooler, along with some low clouds at
times. Cooling will spread inland next weekend, along with more
clouds, and even a chance of showers early next week.

&&

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

At Noon PDT...Satellite imagery showed mostly clear skies across
SoCal except over the mountains and high deserts where cumulus
clouds were building. There were a few spots near the mts reporting
wind gusts from the North at 25-35 MPH, otherwise most areas were
light.

Low pressure is still on track to dig south over SoCal this evening,
pulling a disturbance with it along and west of the mountains. There
appears to be enough moisture and sufficient instability for at
least a chance of showers and isolated thunderstorms, mainly along
the mountains, but some points west could get some light precip as
well. Any shower development will be moving from north to south. By
Tue morning, the low center should be over far NW Mexico, setting up
northern portions of the CWA for some offshore winds. These are not
expected to be strong, but will cause further drying and warming
inland where daytime temperatures will be much warmer this week.
Along the coast, onshore flow is expected to hold a shallow marine
layer, keeping the days much cooler, with some patchy marine clouds
at times.

A broad ridge aloft will dominate the weather through the midweek
period, with fair skies most areas away from the immediate coast.
Temperatures will be some 5-10F above average most areas, although
not nearly as much along the coastal strip due to the marine layer
and afternoon sea breezes.

Looking ahead to the weekend...The 12Z ECMWF/GFS operational runs
continue to show a closed low moving across SoCal Sun/Mon. It looks
strong enough to generate widespread showers at this point, and low
POPS are in the forecast for now, but likely to go higher if the
models stay on track. Increasing onshore flow over the weekend will
bring cooler weather and a deeper marine layer as well.

&&

.AVIATION...
221945Z...Coast/Valleys...FEW-SCT cigs 2000-3000 ft MSL through the
afternoon. ISO -SHRA possible in parts of the valleys and Inland
Empire through early evening. BKN cigs filling in around 2000 ft MSL
redeveloping after 08Z for the coastal TAF sites, pushing approx 15-
20 miles inland. Scatter out expected by 18Z Tuesday.

Mountains...Northwest winds 20-25 kt gusting to 40 kt over the
mountains continue through this afternoon with MOD UDDFS along the
desert facing mountain slopes and into the deserts. Winds
diminishing after 02Z Tuesday, then picking back up after 17Z. Cigs
2000-3000 ft MSL continuing to develop this afternoon. Possible -
SHRA and isolated -TSRA after 21Z lasting into early evening.

Deserts...Mostly clear with VFR conditions through Tuesday. Gusty
northwest winds continue through the afternoon with MOD UDDFS
possible. Brief period of calmer winds after 03Z Tuesday, before
gusting to 25 kts after 17Z Tuesday.

&&

.MARINE...
No hazardous marine weather is expected through this weekend.

.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...10
AVIATION/MARINE...APR

NWS SGX Office Area Forecast Discussion