textproduct: San Diego

SYNOPSIS

Fair and warmer weather with variable high clouds through the end of the week, along with patchy coastal low clouds and fog Wednesday and Thursday mornings. Brisk westerly winds will develop for late Wednesday mainly in the mountains and high deserts. Cooler with increasing clouds for early next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

This afternoon...Warm and dry with variable high clouds. Temperatures are near or a few degrees warmer than at this time yesterday except in the high desert and the San Bernardino Mountains where temps are as much as 15 degrees higher. Weak offshore pressure gradients are trending onshore and a sea breeze is spreading marine air several miles inland.

The ridge of high pressure will continue to dominate our weather into the weekend and the warming trend will continue through Friday. High temperatures today are expected to be in the upper 60s to mid 70s near the coast, in the upper 70s to low 80s in the inland valleys, the 50s to 60s in the mtns, the upper 70s in the high deserts and in the upper 80s in the low deserts. These temps are as much as 13-17 degrees above seasonal averages in the valleys, mtns and deserts. Friday will likely be the warmest day, with temperatures as much as 20 degrees above seasonal averages in the valleys, mtns and deserts. Temperatures on Saturday lower slightly as the upper ridge weakens but will remain 15-20 degrees above seasonal averages.

At the surface, the flow begins to turn onshore today and peaks Wednesday with gusty west winds mainly in the high deserts and the mtns. Onshore flow will continue through Thursday before turning offshore briefly on Friday. The onshore flow will likely bring a return of coastal marine layer clouds/fog for tonight/Wed morning and again for Wed night/Thu morning. High-resolution ensemble models show a 30-40 percent chance of patchy clouds/fog for tonight/Wed morning and a 40-60 percent chance of more widespread low clouds/fog Wed night/Thu morning. On Friday, weak offshore flow will likely disrupt the marine layer.

For Sunday through next Tuesday...numerical models are coming into better agreement with respect to the evolution of the synoptic pattern. At this time, we can say with reasonable confidence that a low pressure system from the northwest will move over or close to SoCal. It will likely bring increasing clouds and cooler conditions. Temperatures on Monday will lower to about 5-9 degrees above seasonal averages. This system could also bring some precipitation but at this time that seems unlikely as only about 25 percent of ensemble members show any chances for precip.

AVIATION

241800Z...VFR conditions expected through the TAF period. Mostly clear skies with high clouds AOA 20,000 ft MSL. Patchy fog based 200- 400 ft MSL is expected to develop after 06Z along the immediate coast with a 10-30% chance of pushing inland around KSAN and north near KSNA. Ceilings and visibilities are not expected to be impactful to coastal airports. Patchy fog will move offshore 16-18Z.

MARINE

No hazardous marine conditions expected through Sunday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

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