Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 180937

Area Forecast Discussion
National Weather Service San Diego CA
237 AM PDT Thu May 18 2017

Mostly clear and warmer weather will begin today as offshore flow
and high pressure aloft settle into the region. Fair and warm
weather will continue into next week, but with increasing coastal



The marine layer is feeling the pressure, literally. High pressure
aloft and an offshore pressure gradient have begun to erode the
deck of marine layer clouds. By late morning mostly clear skies
will prevail and our warming trend will get underway. The dry
offshore flow will peak Friday with northeast winds through the
northern Inland Empire into eastern Orange County. This intrusion
of dry air compressed and heated by downslope flow will allow
temperatures to rise rapidly Friday. The dry air mass continues
through the weekend as the high pressure aloft peaks, even as the
offshore flow relaxes. That will allow temperatures, especially
far inland, to continue to rise into next week while coastal areas
will start to cool a bit as weak onshore flow returns Sunday. A
very weak cutoff low develops to our southwest over the ocean
which will probably send some higher clouds our way and also help
redevelop a marine layer. That cutoff low meanders around our
vicinity next week so expect slightly cooler weather. Coastal
clouds should increase in coverage and duration each night and
morning into the middle of next week.


180900Z...Coast/Valleys/Coastal Mountain Slopes...SCT-BKN020-030
tops 4000 ft through 14Z with vis down to 1 mile in fog where clouds
intersect terrain on the lower mountain slopes. Skies clearing
through 18Z this morning. Coastal stratus expected to be more
limited to the immediate coast late tonight and into Friday morning.

Mountains/Deserts...Winds NNE 15-25 kt with higher gusts to 35 kt
over the San Bernardino Mountains through midday.


No hazardous marine weather is expected through Sunday.


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





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