textproduct: San Diego

SYNOPSIS

Santa Ana winds expected through tomorrow; gradually weakening by later this evening into tomorrow morning, with the strongest and most widespread winds today. Additionally, moderate to major HeatRisk is expected for coastal areas. Cooler conditions will spread inland tomorrow, with greater cooling, increase in westerly winds, and chance of showers for the middle of next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Today through tomorrow night...

With strong and gusty winds in place throughout the night for most locations, temperatures have remained rather warm overnight, with increasing clouds (mostly mid to high level) as an upper level low advanced towards the region from the south. There are some showers (and even a few embedded thunderstorms) viewable on radar over northern Baja California, and this moisture will provide the region with a few light to moderate rain showers being possible, although the lower levels are so dry that if anything were to fall, it would most likely evaporate before it reaches the ground. Still, it cannot be ruled out.

Santa Ana winds will continue today and into tomorrow, but gradually begin to weaken as the pressure gradient loosens with the U/L low pulling away by later this evening and the high pressure centered over the Great Basin weakening as the ridge begins to flatten over the western CONUS. Expect winds to generally gust between 35 and 55 mph for the most wind-proned areas, with local gusts possibly over 60 mph below passes and along mountains slopes/foothills. These downsloping winds will continue to keep temperatures rather warm, especially for the coasts, with low to mid 90s being possible. It should be a couple degrees cooler for most locations than yesterday, especially with the extensive cloud coverage moving in over the region this morning due to the U/L low being in the vicinity. These warm temperatures will also likely keep temperatures elevated overnight, with record high minimums may occur, where winds remain gusty and mixing persists within the PBL. There will be somewhat a decoupling of the winds for tomorrow night, and some areas might have winds become calm enough for there to be some more efficient cooling. For all other locations, the elevated winds will keep overnight lows mild again for tomorrow night. Although there are strong winds in place, RH values have increased a bit from where they were a couple of days ago, with the valleys dropping to around 20 to 30 percent minimums by later this afternoon. This translates to fire concerns still remaining elevated throughout the day. There will only be a very slight chance of there being a few showers this morning for San Diego County, mainly over the mountains and deserts of the southeastern portion of the county. With offshore flow continuing into tomorrow, it will inhibit the marine layer for one more night.

Monday through Thursday...

By Sunday evening into Monday morning, winds will gradually weaken and return to being onshore. Some of the high res members are revealing some low level moisture moving back into the inner SOCAL waters, which alludes to the possibility of there being some patchy fog over the coastal waters, and also along portions of the coastal areas. Some of these areas of patchy fog may also yield denser fog down to below a quarter of a mile. The notable cooldown will begin on Monday as a longwave trough advances towards the region. This will allow for the onshore flow to strengthen going into Tuesday morning, and bring about the possibility of more patchy fog, with better coverage extending further inland. Temperatures by Tuesday will generally be anywhere from 5 to 10 degrees below average. By later in the evening, there may be a few developing showers west of the mountains as an associated major shortwave trough begins to propagate over the region going into Wednesday. This will allow for winds and rain to become more widespread over the region from Wednesday into Thursday as the area of low pressure aloft moves over the area. This will keep the cool and inclement weather sticking around through then, with highs on both Wednesday and Thursday running around 15 to 20 degrees below average for most locations. Snow levels will also drop down to around 8000-8500 ft MSL, with a few inches of snowfall for the higher terrain above. Preliminary rainfall amounts for this storm system look to be around a half an inch to three quarters of an inch for most of the coastal and inland areas, with higher amounts up to around an inch for the San Bernardino Mountains and the Santa Ana Mountains. Stay tuned for more details about this low pressure system in the coming days again.

AVIATION

171000Z...Easterly winds have weakened somewhat across the area. Local gusts 25-35 kts will continue through this morning in the valleys with more persistent gusts 30-45 kts along coastal slopes and adjacent foothills, locally higher for east-facing slopes. Intermittent LLWS expected where winds decouple from the surface (KONT, KSNA, and maybe KCRQ). Easterly winds 20-35 kts continue for coastal slopes and portions of the valleys this afternoon. Winds weaken further and become confined to coastal slopes after 06z Sun.

Otherwise...VFR conditions expected with SCT-BKN high clouds through today. High clouds scatter out across the area tonight.

MARINE

Isolated northeast gusts could exceed 20 knots through this afternoon. Otherwise, no hazardous marine conditions are expected through Wednesday.

BEACHES

A south swell increasing Sunday and Monday will bring elevated surf of 3 to 6 feet for Sunday through Tuesday. Sets to 7 feet along south and southwest-facing beaches. While surf and rip currents will be elevated, high tides will not be particularly high, and the threat of coastal flooding is minimal.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

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

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

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

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

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

PZ...None.