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,
, UPDATED AVIATION DISCUSSION,
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.
040530, SCT-BKN clouds around 2000 to 4000 ft MSL will continue to fill into the inland areas of Orange/San Diego and southern Riverside counties. Areas of -DZ/-RA are possible (15-25% chance) for coastal San Diego County through 07-15z Wednesday, most likely in south county, but aren't expected to lead to any decrease in VIS. There is a relatively high likelihood (70+% chance) that CIGs stay above 3000ft for the most part, but dips to 2500-3000 ft MSL are possible, especially in southern SD County where the -DZ/-RA may occur. Lower clouds start to scatter out around 15z Wednesday. Otherwise, VFR conditions prevailing into the afternoon and evening for tomorrow, with a low chance (less than 10 percent) of cigs based around 2000 to 2500 feet returning to the coastal areas of San Diego after 06Z Thursday and through the end of the forecast period.
Northwesterly winds gusting in the outer coastal waters 20 to 25 knots through early Wednesday morning. Strongest gusts will be found near San Clemente Island and these winds will likely lead to rough, choppy seas. A Small Craft Advisory for this hazard remains through 4 AM 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.
