Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 171128
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
218 AM PST Wed Jan 17 2018

.SYNOPSIS...
A high pressure ridge aloft will keep our weather fair and mild
through Thursday with above average temperatures. High surf will
continue into Saturday, and patchy fog may develop near the coast
each night as well. A fast-moving low pressure trough will drag a
cold front across the region on Friday, with gusty westerly winds
and scattered showers. Precipitation will be light. Fair, dry and
mild again over the weekend and into next week.

&&

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

High clouds were drifting from the north over SoCal and beginning to
thin early this morning, revealing patches of fog. Surface dewpoints
were well into the 50s over coastal areas at 2 AM PST, so a few
hours of clear skies toward dawn may be sufficient for some pockets
of dense fog to form. Weak easterly drainage flow should keep any
widespread fog confined to coastal areas, if at all. The surface
pressure gradient was weak offshore from the deserts.

A high pressure ridge will be building over the SW through Thursday
keeping skies fair and temperatures above average. The ridge will
flatten on Friday as a trough slides east across the State and
deepens. The trough has a modest amount of Pacific moisture to work
with, but will be moving fast, limiting any precip potential across
the Southland. Still, dynamics and moisture look sufficient for at
least some light showers anytime between Fri and Sat morning.

Ahead of the trough, west winds will be increasing on Thu, and
become strong and gusty on Fri into Sat morning over the coastal
waters, mts and deserts. It will be much cooler on Fri/Sat as max
temps fall below average, then gradual warming again early next week
as weak high pressure aloft is reestablished over the SW.

&&

.AVIATION...
171000Z...Coast...Patchy low clouds and fog through 16Z. When/where
these patches occur, bases will vary between 100-800 feet msl, with
vis 0-5sm. Prevailing vis at the coast 4-7sm. A similar patchy low
cloud/fog scenario will develop along the coast after 04Z this
evening. Across most of the region, VFR conditions and scattered
high clouds will prevail today and tonight.

&&

.MARINE...
Patchy fog with vis 1nm is forecast this morning and again tonight.
Onshore flow will increase Thursday and Friday as a storm moves into
the coastal waters. It will bring gales and hazardous seas Friday
and Saturday. Stay tuned to forecasts and other hazard bulletins
when they are issued later this week.

&&

.BEACHES...
High surf will gradually decrease today into Thursday. A new swell
associated with a Pacific storm will arrive Friday, peak Friday
night, and gradually decrease Saturday. Check the High Surf Advisory
and Surf Forecast for details.

&&

.SKYWARN...
Skywarn activation will not be needed through Thursday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory until 8 PM PST Saturday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.

&&

$$

PUBLIC...JAD
AVIATION/MARINE/BEACHES...MM



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