textproduct: San Diego

SYNOPSIS

Strengthening high pressure aloft will bring a warming trend with a long-duration heat wave likely for this weekend through much of next week into the following weekend. The highest HeatRisk is expected for the coast and valleys with widespread Moderate or greater HeatRisk for the coast and valleys for Friday through next week with widespread Major to Extreme HeatRisk for the weekend into next week for inland coastal areas into the western valleys. There will also be periods of gusty easterly Santa Ana winds along and below the coastal slopes of the mountains in Riverside and San Diego Counties for Friday through Sunday.

SHORT TERM (Today through Saturday)

High pressure aloft will strengthen across southern California through the weekend with periods of easterly offshore flow for Friday through Sunday, strongest on Friday and Saturday with east winds along and below the coastal slopes of the mountains in Riverside and San Diego Counties gusting to 30 to 40 mph. The ECMWF Extreme Forecast Index has those easterly wind gusts locally reaching the 80th to 90th percentile on Saturday and Sunday.

High temperatures for the coast and valleys will warm 5 to locally 10 degrees with downslope warming from the easterly offshore flow bringing the greater warming on Friday to the western valleys and inland coastal areas in San Diego County. High temperatures for Friday and Saturday for the coast and valleys will be mostly 15 to 20 degrees above average, except locally 20 to 25 degrees above average for inland coastal and western valley areas in San Diego County.

High temperatures on Friday and Saturday will be around 90 at the beaches with the hottest temperatures for the coast and valleys of 100 to 106 for inland coastal areas into the western valleys. Warming low temperatures for Saturday for the coast and valleys will be mostly in the mid 60s to mid 70s, 10 to 15 degrees above average and locally 20 to 25 degrees above average near the coastal foothills of the mountains in San Diego County.

LONG TERM (Sunday through Wednesday)

While some coastal and western valleys areas could be slightly cooler for Monday and Tuesday, this long duration heat wave is expected to continue through much of next week. HeatRisk will be highest for the coast and valleys with at least Moderate HeatRisk with mostly Major to Extreme HeatRisk areas just inland from the beaches into the western valleys.

AVIATION

010930Z...Coast/western valleys: Somewhat patchy low clouds based 700-1000 ft MSL will continue to fill into western valleys through about 13Z. Areas of vis reductions (1-5SM) expected for areas of elevated coastal terrain and western valleys (I-15 corridor). Clouds scatter back toward the coast 15-17Z. Clouds will be far patchier and intermittent when they reform late Thursday evening, impacting coastal sites late, if they do (30-50% chance for cigs, highest vcnty KSAN).

Otherwise...clear skies today and tonight.

MARINE

No hazardous marine conditions are expected through Monday.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Extreme Heat Warning from 10 AM Friday to 8 PM PDT Thursday for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Coastal Areas-San Diego County Valleys- Santa Ana Mountains and Foothills.

PZ...None.