textproduct: San Diego

SYNOPSIS

Gusty Santa Ana winds will continue through the weekend across the mountains into the inland valleys as an area of low pressure nears the region. This will also bring warmer weather. The system will move southward into Mexico, where there is a small chance for light rain over San Diego County by late Sunday into Monday. High pressure will move over the region for much of next week, bringing warm and dry weather.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Evening update... Skies are clear this evening. Weak offshore flow is ongoing, but surface pressure gradients are beginning to strengthen, currently around -8.4 mb SAN-TPH. Water vapor imagery shows the positively tilted upper level trough across the Desert Southwest. This low will retrograde and deepen as it moves towards So Cal, with a vort max forecast to move across our forecast area tonight. This will cause northeast winds to strengthen, peaking late tonight into late Saturday morning with gusts of 40-50 mph across the mountains, valleys, and inland Orange County. Isolated gusts of 60-65 mph are possible along the coastal slopes of the San Bernardino Mountains and below the Cajon Pass and in the Santa Ana Mountains.

Previous discussion... The area of low pressure will move further south on Saturday into Sunday, which will favor a more easterly wind component around the northern side of the system. These easterly winds will begin to lead to stronger winds across San Diego County during this time period. Highest winds will occur during the morning and afternoon hours each day. Moderate to high chances exist for foothill regions to reach 40 MPH, while valleys see these chances closer to 25-30 MPH. Offshore flow will also bring the greatest warming by Sunday. Western valleys will see moderate to high chances (50-80%) in seeing highs reach 85 degrees. There is about a 50-60% chance to reach 90 degrees across inland Orange County. These high temperatures would be 15-20 degrees above normal for early March. The low will wrap around minimal amounts of moisture with a slight increase in precipitable water values, which may be able to provide light rain showers from the deserts to the western valley regions in San Diego County by Sunday night into Monday. Chances remain low near 15-25 percent with high confidence in light amounts possible.

Ensemble models show good agreement on the movement of this system, pushing it out of the area by Tuesday. High pressure off the coast will move into the area for much of next week. Cooler weather returns on Monday as offshore winds weaken, but a warming trend continues through the week as high pressure off the Pacific strengthens over our region.

AVIATION

070600Z....Coast/Valleys...VFR through Saturday evening. N/NE gusts increase to 20-30 kts after 09z, then increase more significantly after 14z Sat morning to 35-50 kts through the Inland Empire (below the Cajon Pass) and 25-40 kts throughout Orange County. Winds decrease slightly after 21z (still elevated 20-35kts), then greater confidence for more significant wind weakening after 02z Sun, though periods of gusty winds are possible through Saturday evening. Localized areas of LLWS and mod up/down drafts expected, especially in the lee of mountains.

Moderate for gusts above 30 kts at KSNA, 15-20z. Moderate to high confidence for gusts above 35 kts at KONT, 15-22z.

Weaker offshore winds (10-20kts) for the SD County coast after 12z; onshore (NW) winds only reaching areas along the immediate coast, after 18z Sat.

Mountains/Deserts...VFR with FEW-SCT high clouds AOA 20,000ft MSL this evening. Periods of gusty N/NE winds expected through Saturday evening: sustained at 20-35 kts, and gusts 25-45 kts with isolated gusts to 55 kts through mountain passes and on coastal facing foothills. Areas of LLWS and mod up/down drafts in lee (south of) mountains mainly in SBD County. Peak gusts in SBD/OC/Riv Co. mtns 12- 20z Sat; peak gusts over SD Co. mtns not until after 00z Sun.

Low confidence on gusts exceeding 35 kts at KPSP Saturday, most likely 12-16z.

MARINE

Intermittent gusts near 20 knots possible in the outer coastal waters near San Clemente Island early Saturday morning and again Sunday evening. Otherwise, no additional hazardous marine conditions are expected through Tuesday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory until 5 PM PST Sunday for Orange County Inland Areas-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-Santa Ana Mountains and Foothills.

Wind Advisory until 5 PM PST Sunday for Riverside County Mountains-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning.

PZ...None.