Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 162048

Area Forecast Discussion
National Weather Service San Diego CA
145 PM PDT Wed Aug 16 2017

An upper-level trough along the West Coast will maintain a deep
marine layer and below average temperatures Thursday. The trough
will weaken Thursday through Saturday for minor warming and a
shallower marine layer. Another trough will form off the Southern
California coast early next week for cooler weather and a deeper
marine layer.



Marine layer clouds cleared more quickly from the coastal and valley
zones today due to a weaker inversion and thinner cloud layer. Skies
were clear over the mountains and deserts. A West Coast trough
weakens Thursday through Saturday with prevailing dry southwest flow
aloft and low level onshore flow at the surface. The marine layer
will turn a little shallower as heights gradually increase, but low
clouds will spread into the coastal zones and western valleys each
night. Temperatures will remain at or slightly below average.

Early next week shortwave energy over the Pacific will drop down the
backside of the trough. This will once again deepen trough along the
West Coast. The GFS and ECMWF both forecast a 581 dm closed low near
Pt Conception on Monday with increasing onshore flow and a deeper
than normal marine layer early next week. Areas along the coast may
have trouble viewing the solar eclipse on Monday due to possible
marine layer clouds.


162005Z...Coast/Valleys...Clear with unrestricted vis this
afternoon. Low clouds with bases near 1800 ft MSL and tops around
3000 ft MSL will return to the coast and western valleys after 03z
Thursday, spreading up to 20 miles inland overnight. Expect areas of
vis blo 3SM where clouds and terrain intersect. Low cigs could
impact KONT and KSBD aft 09Z, but confidence is not high. Clearing
to the coast is expected between 16Z and 18Z Thursday.

Mountains/Deserts...Clear skies and unrestricted visibility through


No hazardous marine weather is expected through Sunday.


A building moderate period south swell (2-3 ft at 200 degrees) will
arrive in the coastal waters late Thursday and continue through the
weekend. This swell may bring elevated surf (4-6 ft) and strong rip
currents to the beaches Friday - Sunday. No products are being
issued at this time, however a Beach Hazard Statement may be
necessary later in the week.






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