Marine Weather and Tide Forecast for Orange, CA

DISCUSSION
FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Evening update...
Skies are mostly clear this evening over land areas with a few patches of low clouds beginning to develop off the coast. Low cloud coverage will be sparse much of the night, then the HRRR has a 50-60% probability of low clouds in the coastal areas by sunrise Wednesday morning, clearing by mid-morning. Weak transitory upper level ridging moving over the region on Wednesday will bring warmer weather with highs near mid-April normals.

Previous discussion...
An 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 dependent on 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
150400Z
Coasts/Valleys
Mostly clear skies and VFR conditions expected through this evening. Low clouds based around 2000 ft MSL will develop over nearshore waters around 10-13z Wed. 40% chance for coastal TAF sites to experience BKN cigs 12-17z. Clouds scatter out by late morning. Low clouds may redevelop over waters and coastal San Diego County late Wednesday evening, but coverage will likely remain patchy as SCT-BKN high clouds AOA 20 kft move overhead.

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

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.