textproduct: San Diego

SYNOPSIS

Strengthening high pressure aloft into the weekend will bring very hot days for inland areas and warm humid nights except for the highest elevations in the mountains for Thursday into the weekend with record overnight warmth for many areas for Friday and Saturday. Monday and Tuesday will cool a few degrees each day, but high pressure as strong or stronger than late this week could return near the end of next week.

..UPDATED AVIATION DISCUSSION

High pressure aloft will expand westward today and will build into the weekend. This means high temperatures will continue and increase over the next few days.

High temperatures for the coastal areas today will be a few degrees cooler than yesterdays highs, while high temperatures in the mountains and Inland Empire will warm 5 to 10 degrees. Thursday, highs will warm 5 to locally 10 degrees in the valleys and in the coastal mountain slopes with little to no change for high temperatures Friday and Saturday. This will bring seasonal temperatures 5 to 10 degrees above average for most of the area Thursday through Saturday.

Elevated overnight lows will offer little to no reprieve from the daytime heat. Coastal areas and inland valleys will see overnight lows predominately in the 70s, upper 80s to upper 90s in the low deserts, and mid 70s to mid 80s for the high deserts.

These high afternoon temperatures and elevated lows will bring widespread moderate HeatRisk to most of the area with major HeatRisk in the Inland Empire, San Diego mountains and south deserts today, and to include the high deserts Friday through Sunday. Major to extreme HeatRisk indicates that anyone may be negatively impacted by the heat if the proper precautions are not taken. Make sure to stay hydrated, stay cool, avoid heavy activity and direct sunlight and check on the elderly, children and pets.

Coastal low clouds are expected to be patchy in nature and stick close to the coast through Saturday. Some high clouds will move across the area later this afternoon through the evening. A slight increase in monsoonal moisture will create mid-level clouds over the mountains Thursday and Friday with a 10-20% chance for light rain in the mountains for San Bernardino and Riverside Counties.

High temperatures will continue into early next week with some slight cooling for daily high and low temperatures by mid-week. The ECMWF and GFS show high pressure aloft returning by the end of next week that is as strong or possibly stronger.

AVIATION

230000Z....Coast/Valleys...SCT low clouds are lining the SD County coast this evening. Cigs will struggle to develop most likely until after 08z Thu, when there is moderate confidence for BKN cigs over SD County coastal areas up to 15 miles inland. Bases most likely 500- 900 ft MSL. Patchy vis reductions (from BR/HZ): 4-6SM (locally 0- 3SM) over elevated coastal terrain and valleys along the I-15 corridor. Orange County will struggle to develop cigs until after 11z, from south to north. Less than 40% chance for more than 1 hr of cigs overnight at KSNA. Clouds scatter out 15-17z.

Mountains/Deserts...FEW high clouds tonight and small afternoon cumulus over mountain peaks after 21z Thu. Otherwise, VFR conditions prevail through the TAF period.

MARINE

Northwesterly winds with gusts 20-25 kts in the outer waters near San Clemente Island to continue this evening and again Thursday afternoon. Additionally, a mixed swell will cause steep and choppy seas 6 to 7 feet on Thursday and Friday in the outer waters.

BEACHES

A 3 to 4 feet south swell from 190 degrees with 13-15 second period will bring surf of 5 to 7 feet to area beaches Thursday through Sunday. Highest surf will be on south-southwest facing beaches. In addition to elevated surf, tides are expected to increase starting Friday peaking at 5.5 to 6.5 feet MLLW by early next week. The combination of surf and tides will result in minor coastal flooding during high tides.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement from 5 AM PDT Thursday through Sunday evening for Orange County Coastal Areas-San Diego County Coastal Areas.

Heat Advisory from 10 AM Thursday to 8 PM PDT Monday for Orange County Coastal Areas-San Diego County Coastal Areas.

Extreme Heat Warning until 8 PM PDT Monday for Coachella Valley- San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Deserts-San Diego County Mountains- San Gorgonio Pass near Banning.

Heat Advisory until 8 PM PDT Monday for Orange County Inland Areas-Riverside County Mountains-San Bernardino County Mountains-San Diego County Valleys-Santa Ana Mountains and Foothills.

Extreme Heat Warning from 10 AM Thursday to 8 PM PDT Monday for Apple and Lucerne Valleys.

PZ...Small Craft Advisory until 9 PM PDT Thursday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.