textproduct: San Diego

SYNOPSIS

Today features the warmest day of the next week, with highs for inland area 7 to 12 degrees above average. Similar temperatures on Friday are followed by cooler temperatures for this weekend into early next week. A shallow marine layer limited to the coasts and western valleys today and tomorrow deepens for this weekend into next week. Elevated southwest to west winds during the afternoon and evening on Friday and Saturday for the mountains and deserts will gust to 30 to 40 mph. Near to slightly below average temperatures to persist into mid-late next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

New Aviation and Marine discussion...

This morning's sounding shows a stronger subsidence inversion aided by an axis of the subtropical ridge drawing closer. This has allowed the marine layer clouds to be more stubborn than yesterday, clearing for the inland areas, but remain fairly stuck along the beaches and immediate coastal areas. Intermittent clearing is possible through the afternoon, but clouds should stick around for most of the day. Elsewhere, clear skies and mild conditions expected under the building ridge - afternoon high temperatures in the upper 80s to low 90s for inland valleys and upper 90s to low 100s for the deserts, about 7-12 degrees above normal.

The ridge peaks in intensity later today as a large upper trough begins to nudge it's way into the Pacific Northwest on Friday. This helps nudge temperatures down a touch and should help the marine layer clear back more tomorrow as well. As this trough pushes in on Friday into Saturday, the ridge is backs off to the southwest some but an onshore pressure gradient strengthens, allowing for south to southwest wind gusts of 30-45 mph for mountain passes, deserts, and desert slopes Friday and Saturday afternoons. Temperatures also continue to trend cooler through the weekend thanks to the trough, with high temperatures returning back to normal by Saturday. The slow progression of this large trough keeps the cooler temperatures in place into early next week, with highs floating near to slightly below average. As the forecast stretches into early-mid next week, ensembles begin to diverge some, but there is still fairly good agreement in the slow progression of this trough, followed by a secondary reinforcing upper low. Much more disagreement follows regarding the progression of this secondary trough, but the general consensus is that a deep marine layer and cool to near average temperatures should persist through mid-late week.

AVIATION

050440Z...Coast/Valleys...Low clouds are making their way inland over the coastal areas and into the adjacent valleys with cigs currently between 1000-1500 ft MSL. Low clouds will continue to fill into the valley areas, stretching inland 20-25 miles. Bases are expected to lower briefly around 08-10Z 700-1000 ft MSL in SD and 14- 16Z in OC. Localized VIS reductions to 4-6 SM for inland valleys and higher coastal terrain will be possible, with lower VIS where clouds intersect higher terrain. Chances for low clouds have increased to 40-55% for cigs in and around KONT from 10-15Z. Low clouds will clear the valleys after 16-17Z and are expected to cling along most of the coast line through the rest of the period. Cigs will increase in height 17-19Z to 1200-1700 ft MSL. Low clouds will begin to shift inland after 02Z Saturday with similar bases expected.

Mountains/Deserts...Expect clear skies and VFR conditions through the period.

MARINE

No hazardous marine conditions are expected through Monday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

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