Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 250923
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
223 AM PDT Wed Apr 25 2018

.SYNOPSIS...
Fair and seasonal weather will continue this week, with coastal
low clouds and fog nights and mornings. Lower pressure this
weekend into next week will bring cool and brisk weather.

&&

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

The marine layer and coastal clouds are behaving themselves more
predictably this morning. Visibilities are under control; only
reduced in the cloud itself at around 1500 to 1800 feet elevation.
The cloud deck might poke into the Inland Empire through the
Chino Hills and Temecula before sunrise. Weak high pressure aloft
will change very little through Thursday, and the low clouds will
play peek-a-boo with the Inland Empire the next couple nights.
Days will be mostly sunny, with temperatures slightly above
average away from the coast today and Thursday. A low pressure
trough that has cut off from the jet stream will continue to spin
off the Northern California coast. A shortwave from this low will
take a swipe at California on Friday, increasing the onshore
flow. That should extend the coastal clouds farther inland
Friday and also boost the winds through mountain passes and in the
deserts. Then the entire low itself moves through the interior
West over the weekend. The resulting deep but disrupted marine
layer will produce mostly to partly cloudy skies from the
mountains westward, and temperatures will dive below average in
all areas. Winds in mountains and deserts will get pretty strong,
with top gusts at top spots reaching at least 45 mph. A long wave
trough of low pressure will allow some sequence of short waves to
move through it Sunday through Tuesday (and the correlating ridge
of high pressure will finally bring warm spring weather to the
eastern half of the country). Model runs have depicted one or more
of these short waves to produce light showers, but keeps putting
off that chance and can`t seem to nail down the timing anyway. The
uncertainty is too great to even introduce a small chance of rain
at this time. The bigger story anyway will be cooler, cloudier,
and breezier weather next week.

&&

.AVIATION...
250850Z...Coast/Valleys...Stratus with bases 900-1100 ft MSL
continuing to spread 15-20 mi inland this morning. Local vis 3-5 SM
in the valleys, including near KONT, 11-16Z. Stratus and vis
restrictions clearing 16-19Z. Stratus spreading back inland after
26/02Z with bases near 1000 ft MSL. Otherwise, a few high clouds
at/above 20000 ft MSL through Thursday morning.

Mountains/Deserts...A few high clouds at/above 20000 ft MSL with
unrestricted vis through Thursday morning.

&&

.MARINE...
Stronger west to northwest winds will develop in mainly the coastal
waters beyond 30 NM each afternoon and evening Friday through
Sunday with gusts around 25 knots possible.

&&

.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...MM
AVIATION/MARINE...SS


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