Quiet weather with slightly below normal temperatures through Wednesday and gusty winds over the coastal waters. Warmer and drier weather returns late week, with well-above-normal temperatures and weak to moderate Santa Ana winds for the weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Current visible satellite shows high clouds streaming in from the north while low clouds 30 miles off the coastline continue to scatter out. The thermal ridge axis remains over SoCal today, but high clouds will inhibit some of the afternoon peak heating. As such, today will mimic Monday with highs generally in the low to mid 70s for the coast and valleys, 50s for the mountains, 60s for the High Desert and low 80s for the low desert. The ridge axis slides eastward quickly today as a deepening low off the coast advances towards Northern California. As this system moves inland this evening and the gradient tightens, gusty onshore winds will develop over the coastal waters, with a Small Craft Advisory currently in place. Additional details can be found in the Marine Discussion section below.
Tonight as this low moves in, an deepening marine layer across much of San Diego County will support some localized light rainfall early Wednesday morning for far southern SD County. While chances continue to be 15% or less for any given area, a lucky few may experience some wetting rain before sunrise. Otherwise, the general pattern this week remains dry.
The low will move into Nevada on Wednesday, providing one final day of below-normal temperatures before a warming trend returns for late week. With the departure of the low, subsidence builds over CA with temperatures quickly warming to well-above-normal by Friday. Global models continue to set up high pressure over the Four Corners with a substantial ridge stretching from Canada down to Mexico, expected to usher in offshore flow for the majority of California. While the exact set up remains in flux, especially on Saturday, by Sunday, alignment is better on weak to moderate Santa Anas bringing exceptionally warm temperatures and gusty winds to inland valleys and coastal regions. For now, have maintained Santa Ana winds for both Saturday and Sunday, with highs for coastal cities in the upper 80s, quite a bit warmer than even some of the deserts, and minor to Moderate HeatRisk will return for areas west of the mountains. Should the system pan out with a robust high over the Four Corners, easterly wind gusts could reach or exceed 30-40 mph in some of the more wind-prone spots, especially the Inland Empire and coastal Orange County. With these winds, humidity may plummet both days to the teens, even for areas west of the mountains. We are still a bit far out to be nailing out the details, but prepare for a windy, dry, and abnormally hot weekend.
031030, Widespread VFR conditions expected through late this afternoon, with SCT to BKN clouds AOA 20kft at times through late Tue. SCT-BKN clouds around 3000 to 5000 ft MSL move into San Diego Co and south Orange/Riverside counties after 00Z Wed. Likely (60+% chance) these will be above 3000 ft for the most part, but dips to 2500-3000 ft MSL are possible, especially in southern SD County. Areas of -DZ/-RA are likely for coastal San Diego Co after 06Z Wed, most likely in south county, but aren't expected to lead to any decrease in vis. Clouds start to scatter out around 15Z Wed.
Weak winds expected tonight through this morning, before onshore winds strengthen into this afternoon and evening, with gusts in the outer coastal waters 20 to 25 knots through early Wednesday morning. Winds will lead to rough, choppy seas. A Small Craft Advisory for this hazard is in effect this afternoon through early morning Wednesday.
Ca, None. PZ, Small Craft Advisory until 4 AM PST Wednesday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
