textproduct: San Diego

SYNOPSIS

Santa Ana winds expected today through Saturday, with the strongest and most widespread on Friday. Additionally, moderate to major HeatRisk is expected for coastal areas. Cooler conditions will spread inland Sunday, with greater cooling and chance of showers next Tuesday and Wednesday.

..UPDATED AVIATION/BEACHES/MARINE DISCUSSION

Today through tomorrow night...

As an upper level low that has been cut off east of the region establishes itself to the southwest of San Diego, with a high positioned to the north over northwestern Nevada in a rex blocking pattern, the pressure gradient between the two are going to allow for offshore winds to strengthen, initially out of the north to northeasterly direction today, and then becoming more easterly tomorrow. These winds are expected to peak tomorrow, with gusts at around 35 to 55 mph for the inland valleys, and stronger gusts along the slopes, with local gusts approaching 70 mph within some of the higher terrain passes and canyons. As the low taps into some of the remnant tropical moisture from Simon, it will provide a slight increase in humidity tomorrow, and there will be slight chance of a shower or two developing over the mountains during the afternoon hours. RH values will diminish to 15-25 percent by later this afternoon, but then gradually increase to 20 to 30 percent minimum values from Friday, with the influx of moisture. (see fire weather section below). Temperatures will be warmest for the coastal locations, due to the offshore flow. This will also help to impede the marine layer from forming overnight. Highs will be the warmest tomorrow, and for the coastal regions, ranging from upper 80s to low 90s, hence the reason for the Heat Advisory.

This weekend through next Wednesday...

Santa Ana conditions will persist through Saturday, and then these offshore winds will begin to weaken. Temperatures will gradually cool throughout the weekend, and onshore flow will eventually return going into Sunday, which may bring about the onset of some dense fog for portions of the coastal areas during the early morning hours. There will also be an approaching major shortwave trough towards the middle part of next week, which will bring chances of precipitation back into the picture by late Tuesday into Wednesday, along with the return of much cooler temperatures.

AVIATION

151830Z...SKC and VFR through Fri. Northeast winds will remain elevated into Fri, when the strongest and most widespread winds are expected. For the mountain foothills peak gusts of 45 to 55 kt are expected. For the valleys, gusts 30 to 45 kt, locally higher near mountain foothills are likely. Coast and Coachella Valley will also see elevated winds with gusts 20 to 30 kt. There is a potential for gusts of 50 kt to occur at KONT early Fri AM. Winds may decrease briefly after 00Z Fri, increasing around 10Z Fri. Winds Fri will weaken from north to south 18-22Z. Areas of MOD-STG up/downdrafts in lee of (south and west of) mountains along with areas of LLWS where strong winds do not surface. East winds continue into Sat.

MARINE

Isolated northeast gusts could exceed 20 knots Friday into early Saturday. Otherwise, no hazardous marine conditions are expected through Monday.

BEACHES

A south swell from 190 to 200 degrees at 3 to 4 feet with a 15-17 second period will generate elevated surf of 3 to 6 feet, with local sets to 7 feet. There is an increased risk of strong rip currents.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement until 2 PM PDT this afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

Heat Advisory until 8 PM PDT Saturday for Orange County Coastal Areas-Orange County Inland Areas-San Diego County Coastal Areas.

High Wind Warning until 8 PM PDT Saturday for San Bernardino and Riverside County Valleys-The Inland Empire.

High Wind Warning from 8 PM this evening to 8 PM PDT Saturday for San Diego County Valleys.

High Wind Warning until 8 PM PDT Friday for San Bernardino County Mountains.

High Wind Warning until midnight PDT Saturday night for Riverside County Mountains-San Diego County Mountains-San Gorgonio Pass near Banning.

High Wind Warning until noon PDT Saturday for Santa Ana Mountains and Foothills.

Wind Advisory until noon PDT Saturday for Orange County Inland Areas.

PZ...None.