textproduct: San Diego

SYNOPSIS

The trough over the Desert Southwest will continue to push eastward today into Wednesday as high pressure expands off the coast. An area of low pressure enters the mix, where stronger Santa Ana winds and much warmer weather will occur across the region Thursday through Saturday. Confidence is increasing that the heat will be short-lived as another trough moves over the West Coast.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

A 559 mb low currently over Southern Nevada continues to bring the much cooler (and welcoming for some) weather pattern. Current temperatures this afternoon are only in the 60s and 70s west of the mountains and in the deserts, with 40s and 50s across the deserts. Scan your eyes across the sky because that may be the last time you see any large concentrations of clouds this week. The area of low pressure moves further to the east toward the Four Corners Region by Wednesday as high pressure off the coast expands. This will begin a larger warming trend. By Wednesday, temperatures will rise 5-10 degrees with highs mostly near average along and west of the mountains. Comfortable and below normal temperatures remain for the deserts with highs in the 70s and 80s. The wind flow behind this system will start to turn offshore, with portions of the coastal slopes and Inland Empire seeing elevated Santa Ana winds.

As the aforementioned low pressure ejects into the Great Plains, a cutoff low will detach from this as the ridge of high pressure off the coast amplifies into the Pac NW. The pressure gradient between these two systems will tighten, leading to increased Santa Ana winds across SoCal. Winds will begin to strengthen, at first more northerly and northeasterly on Thursday, favoring the San Bernardino Mts and LA Basin region. The low meanders somewhere to our south Friday into even Saturday, which will favor more easterly winds, leading to higher winds in the Riverside/San Diego County mountains and passes. High Wind Watches have been posted for all mountain areas, the Inland Empire and San Diego Co Foothills. Winds will gust near 50-65 MPH at times, locally higher along coastal slopes and the San Gorgonio Pass. All areas are under this watch Thursday and Friday, with San Diego County under the watch until Saturday as uncertainty remains in how long the high winds last.

Santa Ana winds often mean warm conditions west of the mountains! High temperatures Thursday through Saturday will be in the 80s and 90s in these regions. The coastal areas and inland Orange County will see the greatest warming with some spots to see highs in the mid 90s by Friday. NBM shows 30-50% chance that portions of inland Orange County see highs above 95, about 10-30% in the San Diego metro. Low temperatures will also stay above 70 degrees in some spots. A Heat Advisory has been issued for these areas Thursday through Saturday for moderate to locally high heat risk impacts.

Models show the low weakening this weekend into early next week, as a trough begins to enter the Pacific NW. This will turn winds onshore and bring cooling to the region. Models are in fair agreement that the trough will make some headway down the California coastline, which would drop temperatures below normal sometime around Tuesday. If this occurs, cool and breezy weather will accompany this, and even some precipitation by the middle of next week.

AVIATION

131900Z...FEW-SCT low to mid clouds 2500-4500 ft MSL for the coast and valleys and SCT-BKN cumulus based at 8000-10000 ft MSL over all mountains through the afternoon. North winds gusting 25-30 kts after 20Z in San Bernardino Mountain foothills and locally into northeast Inland Empire through 03Z. Weak ENE winds expected early Wed AM across the coastal basin.

MARINE

Isolated northeast wind gusts could briefly exceed 20 kt Thursday afternoon through Friday morning.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Thursday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas.

Heat Advisory from 10 AM Thursday to 8 PM PDT Saturday for Orange County Coastal Areas-Orange County Inland Areas-San Diego County Coastal Areas.

High Wind Watch from Thursday morning through Friday evening for Riverside County Mountains-San Bernardino County Mountains- San Bernardino and Riverside County Valleys-The Inland Empire-San Gorgonio Pass near Banning-Santa Ana Mountains and Foothills.

High Wind Watch from Thursday morning through Saturday evening for San Diego County Mountains-San Diego County Valleys.

PZ...None.