Strengthening high pressure to the east will bring a warming trend through Wednesday with moderate HeatRisk for the deserts. Mid level moisture in southerly flow aloft will bring a slight chance of showers and thunderstorms for this afternoon through Wednesday afternoon for the mountains of San Bernardino and Riverside Counties east and northeastward across the deserts of southern California. This will be followed by a cooling trend for Thursday through the weekend. Southwest to west winds for the mountains and deserts will strengthen through Saturday with gusts on Saturday to 30 to 40 mph with gusts to 65 mph in the northern Coachella Valley below the San Gorgonio Pass.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Thursday), High pressure to the east will continue the warming trend today with slight additional warming of high temperatures on Wednesday. High temperatures on Wednesday will range from a few degrees above average near the coast to 4 to 8 degrees above average inland. High temperatures on Wednesday will range from the lower to mid 70s near the coast to the 90s for the Inland Empire with 108 to 112 for the lower deserts. Tonight will be much warmer as well with low temperatures for early Wednesday mostly in the 80s for the lower deserts. The marine layer will remain around 2000 feet deep with night and morning coastal low clouds extending inland into portions of the western valleys late each night.
Southerly flow between a weak upper level low pressure system off the southern California coast and high pressure centered near El Paso will allow some mid level moisture to be drawn northward into portions of southern California into Wednesday. There is 20 to 30 percent chance for showers and thunderstorms for this afternoon through Wednesday afternoon, mainly for the mountains of San Bernardino and Riverside Counties northeastward across the Mojave Desert. The ECMWF Extreme Forecast Index for precipitation has a large shift of tails for tonight through Wednesday afternoon for this area, most likely a reflection of a few relatively wetter ensemble members during the climatologically driest time of the year for portions of southern California.
(Friday through Monday), A low pressure system moving southward just off the coast of British Columbia will strengthen the onshore slow across southern California into the weekend. Southwest to west winds for the mountains and deserts during the afternoon and evening will strengthen for Thursday through Saturday with gusts on Saturday of 30 to 40 mph with gusts to 65 mph in the northern Coachella Valley below the San Gorgonio Pass. The marine layer will deepen with night and morning coastal low clouds spreading farther into the valleys late each night.
There will be a cooling trend through the weekend with high temperatures on Sunday as much as 15 degrees below average for the mountains and inland valleys. High temperures on Sunday will range from around 70 near the coast to mid 70s to lower 80s for the Inland Empire with the mid 90s to 102 for the lower deserts. High temperatures for Monday of next week will be a few degrees warmer.
230530z, Coast/Valleys, Low clouds with bases 1000-1500ft MSL have infiltrated the coastal areas and will continue to increase in coverage and push inland, up to 15 miles, over the next few hours. Bases are expected to lower 09-13Z up to a few hundred feet. Lower visibilities of 3-6SM can be expected where clouds intersect terrain. Clouds will scatter and retreat to the coast 15-18Z. Low clouds return after 03Z Wednesday with similar bases.
Mountains/Deserts, VFR conditions expected through the TAF period with periodic high clouds AOA 15000 ft MSL after 19Z.
No hazardous marine conditions are expected through Sunday.
Surf will increase Tuesday through Thursday with the arrival of a 3 foot 15 to 18 second period south swell from 190 to 210 degrees. Surf of 4 to 6 ft is expected. Expect locally hazardous swimming conditions and strong rip currents through the week. Please see the Beach Hazards Statement for more details.
Ca, Beach Hazards Statement from 11 AM PDT Tuesday through Thursday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
