textproduct: San Diego

SYNOPSIS

Upper level high pressure system and offshore winds will combine to bring hot and dry conditions to Southern California today and Friday. Daily record highs will be broken in several locations. A return of onshore flow will bring some cooling to the coastal basin over the weekend, but temps will remain above average nonetheless. Relief will be short lived as yet another, stronger ridge pushes in from the west starting Sunday into Monday. This will bring a moderate to locally major heat risk for inland areas along with widespread daily record highs next week.

..UPDATED AVIATION AND MARINE DISCUSSIONS FOR 06Z TAFS

Offshore flow has led to a cloudless sky across Southern California today. This in combination with a strong upper level high pressure system has set the stage for widespread near- record high temperatures and a minor to moderate heat risk today and tomorrow. Lack of marine layer influence will allow 850 mb temperatures near 20 degrees C to mix to the surface, producing temperatures in the 90s in the low deserts and inland valleys. 80s expected at the coastline and 70s in the mountains.

A shortwave trough will pass to the north over the weekend. This will act to somewhat break down the upper ridge and bring back onshore flow. Wind gusts 25-35 mph through the High Desert and along desert slopes will likely be the only sign of its passage in desert and mountain areas. Temperatures in these zones will still be near record highs. However, the coastal basin will see a notable drop in temperatures on Saturday as the marine layer returns to modify the boundary layer. Temps in the 80s inland and 70s along the coast will still be above normal, but not record- breaking. Additionally, there is a chance for low clouds and fog to return to coastal areas Saturday and Sunday mornings. However, scattered high cloud cover may prevent this from occurring.

By late Sunday into Monday, another ridge will begin to push into the region from the west. There is strong model agreement that the ridge axis will move over Southern California mid-next week with 500 mb heights well above 590 dm. This will allow for widespread record-breaking heat to return for all of Southern California through next week with the possible exception of the coastline. For coastal areas, temperatures will be highly dependent on the direction of the flow. A surface high pressure will move into the Plains and parts of the intermountain west behind a storm system by next Monday. If a strong enough pressure gradient develops, then offshore flow will return to Southern California. This would allow coastal areas to also experience record breaking heat. Regardless, most of Southern California will remain hot and dry for the foreseeable future. NBM probabilities of exceeding 110 degrees late next week are near 40% for Palm Springs and 70% for Coachella. In the coastal basin, probabilities of exceeding 100 degrees are 90% in San Bernardino, 80% in Riverside, 30% in Anaheim, and 25% in El Cajon. This indicates an increased chance of breaking March monthly record highs.

AVIATION

130500Z...VFR with SKC-FEW250 through Fri evening.

MARINE

No hazardous marine conditions are expected through Tuesday.

BEACHES

Long period southerly 2-3 ft swell at 19-21 seconds will create elevated surf and a high rip current risk along south and southwest-facing beaches through tonight. Surf heights peaking at 3- 6 feet with sets to 7 feet.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 8 PM PDT Friday 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.

PZ...None.