textproduct: San Diego

SYNOPSIS

Today and Wednesday will be dry with weakening winds with Wednesday high temperatures warming to around average. Stronger onshore flow will spreading cooling inland on Thursday with southwest to west winds for the mountains and deserts gusting to 35 to 45 mph. The flow will turn offshore on Friday with warming for the coast and valleys and continued cooling for the mountains and deserts. Northeast winds along and below the coastal slopes of the mountains will gust to 35 to 45 mph. Warmer inland with weaker winds for next weekend with high temperatures warming to around 5 to 10 degrees above average on Sunday.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Drier and cooler air is in place after the passage of Monday's low pressure system, which now is spinning over the Four Corners region. The last of the moisture remains over the coastal basin in the form of cumulus clouds from earlier this morning, which will mostly clear throughout the afternoon. Slightly warmer weather will be seen on Wednesday as the system departs into the Great Plains and an area of low pressure stays far to the north along the West Coast and U.S. - Canada border. High temperatures will be close to normal for this time of year by Wednesday afternoon with highs in the 70s for much of the coastal basin and high desert with 50s and 60s across the mountain areas.

The area of low pressure over the Pacific Northwest will descend into the Great Basin on Thursday, generating an increase in onshore flow across the region. Gusty west winds will occur in the mountains and deserts, with the exact speeds given by the location of the low and how tight the pressure gradient becomes. There is about a 10-15 MPH spread in wind gusts values from the NBM's 25th to 75th percentiles, indicating some uncertainty. A combination of high resolution models and NBM guidance in yields gusts 30-45 MPH across the deserts with local gusts over 50 MPH in the mountain passes. As the base of the trough passes closer to SoCal and over the Desert Southwest, winds will transition to a Santa Ana wind pattern by Friday. This will bring north and east gusty winds to coastal slope and western valley locations. Again, the exact track of the low will determine how windy it becomes, but wind speeds do look similar to that of Thursday in these regions, probably closer to 20-35 MPH across valleys of Orange County and the Inland Empire. The Santa Ana wind regime will bring a slight warm up to the coastal basin with slightly cooler weather across the deserts.

A transient ridge enters the picture by this coming weekend, bringing less wind and warmer weather across the board. This will bring highs near to slightly above average with 70s and 80s west of the mountains and reaching into the 90s across the lower deserts. Another large area of low pressure system will move closer to the West Coast by early next week. Model guidance continues to show differences in timing, strength, and placement of this system. This will bring cooler and windier weather with the increased chance of precipitation. How much precip and what time (if any) occurs, is still...up in the air. Confidence continues to increase that this weekend will be dry, but we will continue to watch a change in the forecast pattern slated for early next week.

AVIATION

141745Z...Coasts/Valleys...SCT clouds above 3000 ft MSL through the afternoon. Patchy low clouds to gradually form and increase after 10Z Wed. Any cigs that form would be around 1500 feet MSL. Low clouds will scatter out 16-18Z Wed.

Mountains/Deserts...Mostly clear with VFR conditions will prevail into Wed.

MARINE

Wind gusts could briefly reach 20 kt Thursday afternoon and evening. Otherwise, no hazardous marine conditions are expected through Sunday.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.