textproduct: San Diego

SYNOPSIS

The HeatRisk will continue to slowly increase through Saturday with widespread major HeatRisk for the deserts and widespread moderate HeatRisk for Inland Empire and for the mountains below 6500 feet. There will be a slight chance of afternoon showers and thunderstorms for the mountains through next Tuesday with the relatively greater chances for this afternoon and again for Sunday through Tuesday. Gradual cooling and drying will then follow for the rest of next week.

SHORT TERM (Today through Saturday)

Ensemble output shows precipitable water values peaking this afternoon, then declining into Saturday afternoon. The peak hourly REFS 90th percentile rainfall is around 0.75 inch for this afternoon and around 0.25 inch for Friday afternoon. There is a slight chance of showers and thunderstorms for the mountains for this afternoon with slowly decreasing chances for Friday afternoon and Saturday afternoon.

The HeatRisk will continue to slowly increase through Saturday with widespread major HeatRisk for the deserts and widespread moderate HeatRisk for Inland Empire and for the mountains below 6500 feet. High temperatures on Saturday will be a few degrees above average near the coast to 5 to 10 degrees above average for the deserts. High temperatures on Saturday will range from the mid 70s to lower 80s near the coast to the mid 90s to 105 for the Inland Empire with 110 to 114 for the lower deserts.

Night and morning will continue to spread into coastal areas, but with some occasional disruptions in coverage from mid level monsoonal moisture and clouds.

LONG TERM (Sunday through Wednesday)

The Extreme Heat Warning for the deserts and Heat Advisory for the mountains and Inland Empire has been extended through Sunday with only a slight decline in HeatRisk on Sunday. Greater declines are expected for Monday and Tuesday with moderate HeatRisk for next Tuesday confined mostly to the deserts.

Ensemble output shows another peak in precipitable water values for Sunday afternoon, similar to the peak for this afternoon, then a gradual slow decline through next week. A slight chance for afternoon showers and thunderstorms for the mountains will continue for Sunday through Tuesday with gradual cooling and drying for the rest of next week. For Thursday of next week, high temperatures for the deserts and near the coast will be around average and could be as much as 4 to 8 degrees below average for the inland valleys. For Thursday of next week, high temperatures could range from the 70s near the coast to the mid 80s to mid 90s for the Inland Empire with 106 to 110 for the lower deserts.

AVIATION

060600Z....Coasts/Valleys...Areas of low clouds based 1200-1700 ft MSL have developed over coastal areas late this evening. Intermittent cigs at coastal TAF sites should become more persistent by 12z Thu as the low cloud layer slowly becomes more uniform overnight. Clouds may reach up to 20 miles inland Thursday morning before scattering back to the coastline by 16z. VFR conditions expected Thursday afternoon and evening with low chances for any cigs before 06z Fri. Thereafter, clouds will slowly develop over coastal areas with slightly lower bases and patchier coverage than tonight.

Mountains/Deserts...ISO SHRA/TSRA (10% chance) may develop along mtn ridges 20-23z Thu. Otherwise, SCT-BKN clouds AOA 20,000ft MSL with unrestricted VIS through Thursday evening.

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 until 8 PM PDT Sunday for Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains.

Extreme Heat Warning until 8 PM PDT Sunday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.