textproduct: San Diego

SYNOPSIS

Strengthening high pressure will bring warming this week. A long- duration heat wave, with widespread Major to locally Extreme HeatRisk for the coast and valleys, is likely for this weekend through much of next week into the following weekend. Record warm overnight temperatures are likely for the coast and valleys for Saturday through Monday.

SHORT TERM (Today through Thursday)

A thunderstorm developed in the area around Indio Hills in the Coachella Valley on Monday evening with heavy rainfall resulting in flash flooding, strong gusty winds, and more than 1000 lightning flashes and strikes of all types. There have been reports of mud, rocks, and boulders covering portions of Dillon Road near and to the northwest of Indio Hills. A Caltrans sensor along Interstate 10 east of Dillon Road had gusts to 44 mph between 9:30 PM and 10:30 PM.

A closed low pressure system centered over southern Nevada will move eastward across Arizona today with a period of weak offshore lower level flow developing today. For this morning into this afternoon, north winds will gust to 35 to 45 mph in the San Bernardino County mountains with north to northwest winds in portions of the Coachella Valley gusting to 30 to 40 mph. There will also be gusty north winds to 20 to 30 mph in portions of the Inland Empire. Onshore flow will return on Wednesday and weaken on Thursday.

High pressure aloft off the California coast will move across California and slowly strengthen through Thursday. High temperatures for today will warm a few to as much as 5 to 10 degrees. On Wednesday, high temperatures will warm 5 to locally 10 degrees while coastal areas cool a few degrees with the return of onshore flow. On Thursday, high temperatures will warm a few to around 5 degrees with the greatest warming for the inland valleys.

High temperatures on Thursday will be a few degrees above average for the lower deserts and 5 to 10 degrees above average elsewhere. High temperatures on Thursday will range from around 80 near the coast to the 90s for the Inland Empire with the lower deserts in the upper 90s to around 100.

LONG TERM (Friday through Monday)

High pressure aloft will strengthen into the weekend with periods of weak easterly offshore flow during the weekend. Not much change is expected in high temperatures on Friday for the mountains and deserts while the coast and valleys warm 4 to 8 degrees. High temperatures on Friday for the coast and valleys will range from the 80s near the coast to the upper 90s to 105 for the Inland Empire with Moderate to locally Major HeatRisk for the coast and valleys.

Not much change in high temperatures is expected for mountains and deserts for the weekend while coastal areas warm another 5 degrees on Saturday with only slight additional warming on Sunday. Low temperatures for coastal areas will warm from around 70 on Saturday to the lower to mid 70s on Sunday. Widespread Major HeatRisk is expected on Saturday for the coast into the western valleys with Major to isolated Extreme HeatRisk on Sunday.

High temperatures for the weekend will range from around 5 degrees above average for the lower deserts to as much as 15 to 20 degrees above average for coastal areas into the western valleys. High temperatures for the weekend will range from the mid 80s to around 90 near the coast to the mid 90s to 105 for the valleys with the lower deserts around 100.

There could be periods of gusty east winds during the weekend for the coastal slopes of the mountains into the inland valleys with gusts to 25 to 35 mph.

A long-duration heat wave, especially for the coast and valleys, is likely to persist for much of next week into the following weekend.

AVIATION

291745Z...Coast/Valleys: SKC this afternoon and evening. Areas of low clouds based 1500-2000 ft MSL develop over coastal San Diego County starting around 06z Wed. As a coastal eddy takes shape overnight, clouds should spread northward into Orange County and reach 10-15 miles inland by 12z. Clouds scatter back to the coast 15- 17z.

Mountains/Deserts: FEW-SCT mid-level clouds at and above 9 kft through 01Z.

Otherwise...mostly clear skies today and tonight.

MARINE

No hazardous marine conditions are expected through Saturday.

BEACHES

High tides will peak at 6.8-7.1 feet between now and noon today and again late Wednesday morning, leading to minor coastal flooding in low lying areas and coastal erosion. A Coastal Flood Advisory is in effect through Wednesday afternoon.

Please note - mentioned tide predictions in the Advisory have been adjusted to reflect actual measured tide observations.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 5 PM PDT Wednesday for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.