textproduct: San Diego

SYNOPSIS

High pressure to the east will slowly strengthen into the middle of this week with high temperatures for Wednesday and Thursday around 5 degrees above average for inland areas. High temperatures will cool slightly for Friday into early next week to within a few degrees of average for next Monday. Night and morning coastal low clouds will continue into next week. There is also a slight chance of afternoon showers and thunderstorms for the mountains and deserts on Thursday and Friday.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

This afternoon, scattered high clouds are streaming in from the Pacific, caught in the broader clockwise high pressure flow across much of the western US. Temperatures are running generally 1 to 4 degrees F warmer than yesterday with more 100 degree readings expected across the Inland Empire and more 90 degree readings throughout inland areas east of I-5 in Orange County and east of I- 15 in SD County.

Low clouds will struggle to develop initially tonight but will eventually fill into coastal areas in patchy fashion and lead to patchy fog in the some of the elevated inland valleys around I-15 in San Diego County. High clouds streaming through the region will continue to disrupt low cloud development in the following evenings as well.

Hotter low-tropospheric air from the Desert Southwest will continue to stream into Southern California, which will allow temperatures to increase into Wednesday throughout the Inland Valleys. Similar high temperatures are expected Thursday: 98-105F in the Inland Empire and interior valleys like Ramona, Alpine...For these areas, highs may decrease a degree or two into Friday, then another few degrees into Saturday but still remain a degree or two above seasonal average.

Meanwhile, desert and coastal temperatures remain rather stable, mostly un-phased by the positioning of the ridge, but still a few degrees above average. Coastal communities will generally see highs in the low to mid 80s while cities more inland (Anaheim, Escondido...) will see highs in the upper 80s and low 90s. The Coachella Valley and San Diego County deserts will see highs between 108-114F through next week.

As the ridge moves into the Four Corners region, the flow of monsoonal moisture opens up and brings along a slight chance for afternoon mountain thunderstorms Thursday through the weekend. At this time, there is great uncertainty in terms of how much t-storm activity occurs during this timeframe as long range model solutions range from scattered activity each day to none at all. PWAT's are generally highest Thursday and Friday, though instability increases Saturday through early next week as the ridge moves eastward.

AVIATION

181740Z....Coast...SCT-BKN high clouds through the TAF period. Patchy BKN low clouds impacting TAF sites intermittently between 10- 15Z Wed near 700-1000 ft MSL. Best chance for cigs will again be in San Diego County. Complete scatter out between 15-17Z.

Otherwise...VFR prevails with SCT-BKN high clouds AOA 15000 feet MSL through the period.

MARINE

No hazardous marine conditions are expected through Saturday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory from 10 AM Wednesday to 8 PM PDT Thursday for San Bernardino and Riverside County Valleys-The Inland Empire.

PZ...None.