Warmer conditions for the middle to end of the week with above average temperatures. The marine layer is expected to get shallower with night and morning low clouds and fog not reaching as far inland. There is a a slight chance of showers and isolated thunderstorms over the mountains Thursday afternoon, with otherwise dry conditions expected to prevail. Cooler conditions may return for early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Sunnier skies are expected this afternoon with high temperatures running near to up to 7 degrees warmer than yesterday. The marine layer is expected to get shallower over the next few nights, staying mostly confined the the coast. Conditions will warm through the middle of the week.
Wednesday, high temperatures will warm 5 to 12 degrees for the valleys, with 3 to 5 degrees of warming elsewhere. Additional warming is expected through Saturday with temperatures along the coast with the highest departure from normal at 7 to 12 degrees. For the latter half of the week, overnight lows will increase to the mid- 60s to 70 west of the mountains and in the upper 70s to low 80s in the low desert. Moderate HeatRisk is expected along the coast Friday and Saturday and in the low deserts for the second half of the week. Moderate HeatRisk has the most impacts on those sensitive to heat, especially those without cooling/hydration. A low pressure system is expected to move inland early next week which will bring cooling conditions and a deeper marine layer.
For Thursday, a closed low lingering to our southwest will start to move east. This will draw moisture into Southern California from the southeast increasing chances for precipitation, mainly in the mountains. There remains a 10% chance of thunderstorms over the mountains.
Tropical Cyclone Polo, currently off the southwest coast of Mexico, is now a major hurricane. Polo is basically stationary but is expected to move generally west-northwest over the next few days. There remains a lot of uncertainty in the forecast for late in the weekend into next week but there could eventually be at least some peripheral impacts to portions of Southern California. Right now, it looks like the most likely impacts will be coastal flooding and erosion but that will ultimately depend on the track, intensity, and duration of the cyclone.
221800z, Coast/Valleys, Nearly all low clouds have cleared out this morning, with VFR conditions expected to prevail into the afternoon. Clouds with lower bases (initially around 2000-2500ft MSL) look to redevelop across coastal San Diego County after 00z Wednesday. High confidence in CIGs at KSAN, lower confidence at KCRQ between 00-06z. After 06z, CIGs look to spread throughout coastal SD County and northward towards Orange County, with bases likely lowering to around 1500ft MSL. Moderate confidence in CIGs at KSNA between 11-16z. Clouds scatter out between 16-17z Wednesday.
Otherwise, Mostly clear skies today and tonight.
No hazardous marine conditions are expected through Sunday.
Ca, None. PZ, None.
