textproduct: San Diego

SYNOPSIS

Moderate to locally strong Santa Ana winds will continue along the coastal mountain slopes, foothills, and into the valleys through Sunday. Periods of weaker Santa Ana winds will continue through the remainder of the week. A warming trend develops this weekend, with temperatures peaking around the middle of next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Evening update... Water vapory imagery shows a short wave behind the departing trough digging south across So Cal. Mid-level flow will turn more easterly, driving stronger winds across the San Diego County Mountains and below the San Gorgonio Pass tonight, while areas more prone to north to northeast winds have already seen their peak and will weaken slightly over the weekend. This short wave is forecast to develop into a closed low over central Baja by Sunday, with modest upper level support continuing over So Cal. At the surface, pressure gradients are forecast to peak late Saturday into Sunday morning. This is when the strongest easterly winds are expected with isolated gusts to around 70 mph below the San Gorgonio Pass and coastal slopes of the Cuyamaca Mountains. The Wind Advisories for the San Gorgonio Pass and San Diego County Mountains were upgraded to a High Wind Warning this evening, valid through 1 PM Sunday. Remaining Wind Advisories and the High Wind Warning for the San Bernardino Mountains remain in place through 1 PM Sunday as well.

Surface pressure gradients weaken late Sunday and Monday, allowing winds to weaken. Santa Ana winds will likely continue through at least Friday. The CW3E West-WRF maintains a 15-20% of at least a moderate strength event Tuesday-Thursday, and a 60% chance of at least a weak event.

Previous discussion... As long as the offshore flow persists, relative humidity will remain low. Daytime RH drops into the 10-20% range this afternoon and Saturday afternoon and continue to drop into the 20-30% range into next week, with overnight recoveries capped at only 35-40% in the mountains. Fire danger will be limited as the fuel moisture levels are high from recent rains.

Temperatures today are slightly below average, in the low to mid 60s in the lowlands. Temperatures climb 2-5 degrees F each day from today through Wednesday as a very longwave ridge slowly develops across the Western US and Northeast Pacific. WPC model clusters show the ridge likely centering off the Pacific Northwest though upper heights will increase as a result well into northern Mexico. With daytime heating, temperatures are likely (80% chance) to reach above 80 degrees in the valleys next Wednesday and Thursday. Next Friday and beyond, there is moderate to high confidence that the ridge remains strong off of British Columbia, although there are model solutions suggesting the possibility for an upper low to form near or retrograde into the southwest US, which could at the minimum cool our temperatures back closer to average.

AVIATION

100400Z...Coast/Valleys/Mountains...Mostly clear skies prevailing. Northeast and east winds gusting 35-50 kts along coastal slopes. Gusts of 25-35 kts expected through the Inland Empire and into inland Orange County, including VCTY KONT/KSNA, mainly during the early hours overnight and tomorrow afternoon. Periods of LLWS and moderate up and downdrafts downwind of coastal slopes (i.e. KONT, KSNA, KSBD). Wind pattern continues through much of Saturday and into early Sunday morning.

Deserts...VFR conditions through the period. Strong northeast wind gusts staying mostly confined to mountain slopes, with winds generally below 20 kts, and occasional gusts up to 30 kts.

MARINE

Northeast to east winds will occasionally gust to 20 to 25 knots through this weekend. Otherwise, no hazardous marine conditions expected through Wednesday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory until 1 PM PST Sunday for Orange County Inland Areas-Riverside County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Valleys-Santa Ana Mountains and Foothills.

High Wind Warning until 1 PM PST Sunday for San Bernardino County Mountains.

High Wind Warning until 1 PM PST Sunday for San Diego County Mountains-San Gorgonio Pass near Banning.

PZ...None.