Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

138 pm PDT Fri aug 17 2018


Monsoonal moisture will bring some thunderstorms mainly to the mountains this afternoon. Warmer and drier weather is expected Saturday through Monday. For Tuesday and Wednesday, monsoon moisture will increase, bringing a chance of afternoon thunderstorms for the mountains and deserts. Coastal areas will continue to get areas of night and morning low clouds.


For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,

Several thunderstorms have erupted in the mountains and are dropping locally heavy rain. They might cause some problems with severe damage or flash flooding this afternoon. But they won't be as numerous or as widespread, or as evil, as they were yesterday, although instability is still quite high so any individual storm could grow pretty strong. Thunderstorms should dissipate fairly rapidly after about 6 pm as monsoon moisture and instability decrease. The atmosphere dries out a little more this weekend, although we'll see some cumulus clouds build over the mountains each afternoon. With the higher pressure aloft, the coastal clouds will be relegated to the coast and far western valleys each night and morning. Temperatures will climb inland a few degrees this weekend, and a few more Tuesday and Wednesday. When will the thunderstorms return? Right now it appears to be Tuesday through Thursday. Which day will have the most thunderstorms still eludes us becauses guidance varies on that question. All next week look for seasonal August weather with a shallow marine layer and varying chances of mountain thunderstorms each afternoon.


172000z, Coasts/Valleys, BKN/OVC coastal stratus will begin to spread back inland after 00Z this evening, with similar bases to this morning, with bases 1300-1800 ft MSL and tops to 2200 ft MSL. Stratus should clear to the coast 16-18Z Saturday morning, with some clouds lingering at the beaches into Saturday afternoon.

Mountains/Deserts, Scattered TSRA over the mountains and deserts through this evening, with strong up/downdrafts, LLWS and surface wind gusts to 40 knots. CB bases will be around 8000 ft MSL with tops to 45000 ft MSL. Otherwise, FEW-SCT clouds at/above 10000 ft MSL, with vis unrestricted outside of TSRA.


No hazardous marine weather is expected through Wednesday.


Beach Hazard Statement has been extended through Saturday for elevated surf and strong rip currents. A 4 ft/16-17 second period swell from 180 degrees will bring surf of 3-6 ft, with isolated sets to 9 ft, mainly along the south facing beaches of Northern Orange County, and strong rip currents. Surf will lower Saturday night through Sunday.

Watches, Warnings, Advisories

Ca, Beach Hazards Statement through Saturday evening for Orange County Coastal Areas-San Diego County Coastal Areas.


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