A low pressure system moving southward off the California coast will bring general cooling through Thursday. It is also expected to produce showers and a slight chance of thunderstorms for late Wednesday through Thursday is it moves inland through California into Nevada. Warmer and drier for next weekend. Offshore flow on Saturday could produce gusty northeast to east winds in and below mountain passes and canyons as well as the Inland Empire corridor between the Cajon Pass and the Santa Ana Mountains. The offshore flow weakens for Sunday into early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This afternoon, Skies are partly cloudy with only a few low clouds off the coast, some mid and high clouds streaming in from the southwest and cumulus clouds developing over the mountains. Isolated showers over the mtns this afternoon can't be ruled out but the chances are very low. Temperatures are generally a few degrees lower than at this time yesterday.
The low pressure system west of Point Conception continues to move south today before turning east tomorrow. It will move through SoCal on Thursday and Friday. It will bring further cooling, a deepening marine layer with more low clouds, and widespread precipitation. Showers could spread into coastal areas during the afternoon on Wednesday. Those showers are expected to spread farther inland for Wednesday night into Thursday with the greatest chances for thunderstorms for late Wednesday night into Thursday.
Between Wednesday and Thursday night, rainfall across Orange and southwestern San Bernardino Counties could range from around 1 inch near the coast to as much as 2 inches in the mountains. Rainfall for San Diego County will range from around 1 inch in North County to 0.50 to 0.75 near the border. High desert areas will receive around 0.50 inch of rainfall and the low deserts will receive 0.25 inch or less. Probabilities for 0.10 inch or more of rainfall from Wednesday morning through Thursday night exceed 90 percent for the coast, valleys, and mountains. Probabilities for 0.50 inch or more exceed 80 percent for the mountains as far south as the northern half of San Diego County. Probabilities for 1 inch or more range from 15 to 50 percent from the coast to the mountains for Orange and southwestern San Bernardino Counties. Probabilities for 2 inches or more exceed 10 percent for the mountains of southwestern San Bernardino County.
High temperatures on Thursday will range from around 5 degrees below average near the coast to 15 to 20 degrees below average for mountain elevations above 6000 feet. High temperatures on Thursday will be in the 60s to around 70 for the coast and valleys and in the 40s and 50s for the mountains.
Precip tapers off late Thu into Fri as the low pressure system moves eastward into AZ.
Warming and drying is expected for the weekend into early next week, with some weak offshore winds possible Saturday and Sunday. Offshore flow on Saturday could result in northeast to east winds gusting 30 to 40 mph in and below mountain passes and canyons as well as the Inland Empire corridor between the Cajon Pass and the Santa Ana Mountains. The offshore flow weakens on Sunday.
For Saturday through Tuesday, high temperatures for coastal areas will range from 5 to locally 10 degrees above average with inland areas around 5 degrees below average to locally 10 degrees below average in the mountains. High temperatures for the coast and valleys will be mostly in the mid 70s to lower 80s with the lower deserts in the lower to mid 80s with the mountains in the 50s and 60s.
210000z, Coast/Valleys, Low clouds based around 1800-2200 feet MSL will develop over coastal areas and western valleys in the next few hours. Low clouds fill into the southern Inland Empire after 06z Wed and potentially fill into the northern Inland Empire overnight. There's a 30-40% chance for cig impacts vcnty KONT/KSBD. Vis reduced 3-6SM for elevated inland valleys. Low clouds scatter out relatively early (13-16z) due to increasing upper cloud cover and decreasing stability.
.Region-wide, SCT mid-level Cu over mtns and portions of the coastal basin currently will slowly dissipate through this evening. A band of -SHRA/SHRA will move through the region from west to east Wednesday afternoon and evening. There is still some uncertainty in exact timing, but impacts may start near KSNA/KONT as early as 21z Wed and slowly progress eastward through the evening. A few hours of 2000-3000 ft cigs and intermittent MVFR vis expected for each TAF site in the coastal basin. A few embedded heavier showers may produce local IFR conditions, mainly north of SD County. Winds shift from south to southwest as the precip band passes through.
A storm system will move through the coastal waters late Wednesday through Thursday. Southerly winds Wednesday will shift to southwesterly Wednesday night, then westerly Thursday, with occasional wind gusts exceeding 20 knots. There is a 10-20% chance of TSRA Wednesday night through Thursday. No additional hazardous marine conditions are expected Thursday night through Sunday.
Southerly swells will continue to bring surf of 3 to 5 feet with sets to 6 feet, highest at south and southwest-facing beaches through this evening (locally to 7 feet at Huntington Beach/The Wedge). This will bring hazardous swimming conditions for most. While surf and rip currents will be elevated, daily high tides will not be particularly high, and the threat of coastal flooding is minimal. See the Beach Hazards Statement for more details.
Ca, Beach Hazards Statement until 11 PM PDT this evening for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
