Area Forecast Discussion

SYNOPSIS

Cooler weather for inland areas is expected this weekend into the first half of next week as a trough of low pressure moves over the region. This will also bring breezy conditions across the mountains and deserts this afternoon and tomorrow afternoon. High pressure looks to expand over the West Coast by the latter half of next week, which would lead to a warming trend.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

..UPDATED aviation discussion for 18Z TAFs

Today through tomorrow night...

Current satellite imagery reveals that the marine layer has formed and filled in along the coastal areas for San Diego and Orange counties, and extends roughly around 10 to 15 miles inland with bases of around 1500 to 2000 ft elevation. Given how strong the inversion is in place over the region, it is likely that the marine layer will struggle to mix out and dissipate later this afternoon, especially for locations right along the coast, where there will likely be low clouds lingering throughout the afternoon.

High pressure conditions continue to dominate the region, however, there is a major shortwave trough upstream that is advancing eastward and beginning to influence the area with cooler temperatures with a better push of onshore flow, and breezy conditions, especially for the mountains and areas prone to gusty winds. These winds are not expected to reach advisory level, although there may be a few occasional gusts approaching 60 mph within the San Gorgonio Pass. By later this evening, these winds will begin to decouple overnight, but then pick back up to be gusty again on Sunday during the afternoon, being slightly weaker. Temperatures will be around the same for highs on Sunday, perhaps just a smidgen warmer.

Monday through Friday...

There has been very little change in the extended forecast since previous model runs. As the trough exits the region towards the middle of the week, and as the overall longwave pattern begins to shift more east and allows a ridge over the E PAC waters to expand over the west coast region, it will allow for there to be a gradual warming trend occurring towards the end of the upcoming week. This will also allow for the marine layer to lower with possible vis restriction impacts as a result closer to the coastal areas. Conditions are expected to remain dry through then.

AVIATION

061800Z...Coast/Valleys...Low clouds 1800-2200 ft MSL are lingering along the immediate coast this morning. Scattering possible 19-23Z today for coastal sites, higher chances for north SD County/Orange County. Scatter out for south SD County likely to be intermittent and brief, with sustained BKN cigs for most of the day. Clouds move back inland after 23Z this afternoon, reaching into parts of the inland valleys similar to this morning overnight, with similar bases 1800-2300 ft MSL.

Mountains/Deserts...VFR with clouds AOA 20000ft MSL through this evening. Southwest-west winds will increase in the mountains and deserts today with gusts reaching 30-40 knots after 19Z. Winds slowly decrease late this evening and overnight. MOD up/downdrafts and pockets of LLWS in lee (north and east) of mountains.

MARINE

No hazardous marine conditions are expected through Wednesday night.

BEACHES

A series of long period (17-19 second) swells from the south (200 degrees) will result in elevated surf this weekend. Surf 4-6 feet at south facing beaches remains through this evening, before swell and surf diminishes slightly on Sunday. Surf builds again Monday as a fresh 3-4 foot swell at 18-19 seconds moves into the region. Surf peaks Tues-Wed with sets to 5-8 feet likely at south-facing beaches, then gradually diminishes late next week.

SGX WATCHES / WARNINGS / ADVISORIES

CA...None. PZ...None.