textproduct: San Diego

SYNOPSIS

Windy over the mountains and into the deserts, well below average temperatures across Southern California, and a deeper marine layer can be expected this weekend. Areas of drizzle are possible, with Saturday morning as the most likely day. Conditions will gradually warm into next week.

Updated Aviation Discussion for the 06z TAF Package

A unseasonable trough of low pressure is expected to dig into the Great Basin this weekend. This will increase the onshore pressure gradient, resulting in stronger westerly winds on the desert mountain slopes into the deserts, well below average temperatures, and a deeper marine layer. By Sunday, highs are expected to be 7 to 9 degrees below average at the coast and low deserts and 15 to 20 degrees below average in the valleys, mountains, and High Desert. There is also a potential for patchy drizzle west of the mountains, most likely on Saturday morning.

Winds on the desert mountain slopes and in the deserts will strengthen into Saturday. Wind gusts Friday will be 35 to 50 mph, combined with relative humidity 7 to 15 percent in the deserts will create periods of near critical to locally critical fire weather conditions in the deserts. For more information on fire weather concerns, see the Fire Weather section below. Winds are expected to peak in strength on Saturday afternoon and evening, with peak gusts 50 to 65 mph with locally higher gusts possible below the San Gorgonio Pass. Winds will decrease Sunday into next week.

Global ensembles are indicating broad scale weaker troughing may linger into the end of next week. Even with the lingering troughing, heights will rise leading to a gradual warming. About 27 percent of ensemble guidance is indicating a ridge may begin to build back in by next weekend. By next Thursday, highs will be 3 to 7 degrees below average. Additionally, the weak troughing will maintain a deeper marine layer into at least the middle of next week.

AVIATION

260530Z...Coast/Valleys...Patchy low clouds based 1600-2200 ft MSL are expanding in the lowlands, eventually reaching into the inland valleys by 08z, and partially filling in to the Inland Empire 07- 13z. Minor vis reductions (3-6SM) expected for elevated inland valleys (KSBD, KRNM). Clouds clear toward the coastline 15-18z Fri with SKC expected for the afternoon. Patchy clouds with slightly higher bases are expected to develop near the coast around 01-04z Sat before pushing inland again.

Mountains/Deserts...Mostly clear and VFR conditions expected through Friday evening, except for coastal slopes shrouded in fog below 3500 feet MSL 10-15Z Friday. West-southwest winds gusting 20-30 kts gusts and up to 45 kts through mtn passes to remain localized through Friday morning before increasing after 21z. Gusts 25-40 kts to occur Friday evening in parts of desert valleys and slopes with gusts locally to 55 kts through the passes. There is a 25% chance for gusts exceeding 35 kts Friday evening at KPSP and higher chances in the vcnty, north and east of KPSP. Occasional MOD up/downdrafts in lee of mountains.

MARINE

Breezy NW winds gusting over 20 kts Saturday afternoon and evening near San Clemente Island will create hazardous conditions to small craft. Otherwise, no additional hazardous marine conditions are expected through Wednesday.

BEACHES

While the long-period south swell has diminished, a brief uptick in period (15-17 seconds) Friday afternoon will create locally elevated surf up to 5 feet along south facing beaches.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory from 11 AM Friday to 5 AM PDT Sunday for Apple and Lucerne Valleys.

Wind Advisory from 5 PM Friday to 11 AM PDT Sunday for San Diego County Deserts.

Wind Advisory from 11 AM Friday to 5 PM PDT Sunday for San Gorgonio Pass near Banning.

PZ...None.