textproduct: San Diego

SYNOPSIS

A few sprinkles or light showers will continue through tonight but any measurable amounts are unlikely. Dry and warm conditions expected over the weekend with weak Santa Ana winds. A pattern change is expected next week, bringing cooler conditions, periods of gusty southwest to west winds, and chances of widespread precipitation.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

A couple of showers developed over the San Gabriel Mountains just over the county line in LA County earlier this afternoon. They seemed to have the potential for it but no lightning strikes were detected. Currently, a closed upper low will continue to bring mid and high level sub-tropical moisture into SoCal from the south and sprinkles or light showers will continue to move northward through much of tonight. Very little, if any, precipitation will reach the ground as most of it will evaporate in the dry sub-cloud layer.

From previous discussion... The closed upper level low off the California coast will continue to move southeast, reaching Baja California early Sunday. The southerly track of the low will allow an upper level ridge to build over Southern California and for weak offshore flow to develop. The combination of these will bring an uptick in high temperatures for the weekend. Highs will peak on Sunday at 10 to 18 degrees above average.

A change in the overall upper level pattern is expected for next week. The effects will be felt as early as Monday, with temperatures expected to be 3 to 5 degrees cooler than Sunday. Further cooling is expected through next week as broad troughing prevails over the Western United States. In addition to cooler conditions, marine layer low clouds and fog will likely reach into the valleys, with the potential to reach the mountain slopes at times.

This pattern is also expected to bring periods of widespread precipitation. Current forecast has precipitation chances starting as early as Tuesday, but there remains uncertainty in the timing of the trough passage and the trough's track. About 35 percent of ensemble solutions show the trough axis reaching the central California coast on Tuesday, which would bring precipitation. By Wednesday, the solutions increase to about 60 percent, with similar percentages for Thursday and Friday. Most of the individual ensemble members are indicating light rainfall amounts, with only a few members showing moderate amounts. Mountain snow is possible for the the middle to end of next week. There remains uncertainty in snow level due to uncertainty in the forward progression of the low and it's ultimate track. NBM 25th and 75th percentile has snow levels between 5500 and 7000 feet respectively. Increased westerly winds over the mountains and into the deserts are also possible depending on the track of the low. Latest ensemble guidance has the peak of the winds Tuesday afternoon, with more spread in wind speeds into Wednesday and Thursday.

AVIATION

070445Z....Coast/Valleys...VFR conditions prevailing currently with FEW-SCT low clouds developing in San Diego and Orange Counties. Coverage should increase over the next few hours allowing for areas of BKN cigs with bases 2000-2500 ft. Clouds expand into portions of the Inland Empire 08-11Z Sat. Low clouds scatter out of most land areas 13-16Z, but may linger over coastal Orange County through 18Z. The return of low clouds may start as early as 00Z Sun for coastal San Diego County with lower bases around 1000-1500 ft MSL. Light offshore flow should keep coverage of low clouds patchy and confined to coastal areas Saturday night with bases continuing to lower overnight.

Mountains/Deserts...VFR conditions through the period with FEW-SCT high clouds above 15kft through tonight.

MARINE

Westerly swell (280 degrees) at 15-16 seconds will bring seas of 6-9 feet in the outer waters near/around San Clemente Island through Saturday. This may also lead to localized steep, rough conditions near the bay entrances, including the entrance to the San Diego Bay/Zuniga Shoal area and Oceanside Harbor. Otherwise, no hazardous marine conditions are expected through Wednesday.

BEACHES

Increasing long-period (15-16 second) swell from the west-northwest (280 degrees) will bring elevated to high surf of 5-8 feet with locally higher sets to 10 feet through early Sunday morning. Impacts will be greatest at west facing beaches, especially across southern San Diego County, and there will be a high risk for rip currents. This may also lead to minor tidal overflow for low-lying beach areas during high tide late tonight into early Saturday morning. Further information can be found in the High Surf Advisory.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...High Surf Advisory until 6 AM PST Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.