textproduct: San Diego

SYNOPSIS

High pressure over the eastern Pacific and across the southern US will keep temperatures slightly above normal through early-mid next week across Southern California. Moderate HeatRisk is expected for the deserts each day with localized Major HeatRisk in the lower deserts over the weekend where low temperatures will run 10-15 degrees above normal. The marine layer will remain relatively shallow with morning clouds remaining confined to coastal areas and western valleys through the weekend.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Satellite shows the marine layer has cleared out nicely this morning with mostly sunny skies expected through the day. 500mb RAP analysis shows fairly neutral flow aloft, with a weak upper low off the south- central Baja coast, the subtropical ridge in the east Pacific, and a broad ridge across the southern United States. Under this pattern and the effects of the nearby ridges, temperatures today will be notably warmer than yesterday and are expected to be a few degrees above normal. Afternoon highs feature 70s along the coast, mid 80s to low 90s for inland valleys and 100-107 degrees for the deserts.

Over the next few days, the weak upper low slides southwest, allowing the southern US ridge to slide westward and establish southwesterly flow aloft. Aside from this, little change in the upper level pattern keeps us locked in a similar setup into early next week, with high temperatures staying constant and 5-10 degrees above average. The only notable effect of this pattern will be a marginal surge of mid-level moisture set flow into the region from the southwest Thursday night, likely sticking around into the weekend. A subtle shortwave on the southwestern edge of the broad ridge to our east may be able to spawn a few light showers across the mountains/deserts of San Diego County on Friday. There is only about a 15% chance of any precipitation at this time and any rainfall amounts will likely be little to none. Other than the slight rainfall chances, the other main consequence of this increased moisture will be abnormally warm overnight low temperatures in the deserts - likely 10-15 degrees above climatological norms. Though no daytime high temperatures records look to be threatened, the very warm nights expected in the deserts could challenge a few warm low temperature records Friday/Saturday mornings.

Heading into mid next week, the amplified ridge over the eastern Pacific weakens as it spreads into the western US. Clusters and global ensembles do begin to diverge in the evolution of the upper pattern at this point, with many models suggesting the return of upper troughing and some relief to the above normal temperatures.

AVIATION

102100Z...Coast/Valleys...Low clouds have cleared the coast with a few clouds wafting in around 1000-1600 ft MSL. Low clouds will start to push in again after 23Z beginning along San Diego's coast line and fill in after 03Z Thursday. Bases are expected to be around 800- 1200 ft MSL. Minor vis reductions (4-6SM)will be possible for elevated coastal terrain. Clouds clear TO the coast after 17-18Z Thursday.

Mountains/Deserts...VFR conditions expected through the TAF period.

MARINE

No hazardous marine conditions are expected through Saturday.

BEACHES

Elevated surf and strong rip currents expected through Thursday afternoon. The surf peaks today, with surf 4-8 feet and sets up to 10 feet at south-facing beaches. Surf will gradually lower late this week. See the Beach Hazards Statement for more details.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Thursday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.