Dry and warm conditions expected this weekend. Cooler, windier, and wetter conditions expected for the middle of next week. Additional rounds of unsettled weather are expected next weekend and potentially into the following week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Temperatures at noon today were running 5 to 10 degrees warmer than noon yesterday for many inland locations. High pressure aloft is expected to build over Southern California into Sunday. Influence from the high combined with weak offshore flow at the surface will result in an additional 3 to 7 degrees of warming across the area. That will raise high temperatures to 10 to 15 degrees above average for most locations, locally close to 20 degrees above average on Sunday. The high is expected to weaken on Monday with weak onshore flow returning. That will allow for a few degrees of cooling, mainly for areas west of the mountains. A broad troughing pattern will remain in place for much of next week, maintaining near to slightly below average temperatures.
There is generally good consensus among global models that a shortwave will move through the mean flow Tuesday evening into Wednesday. In addition to cooler conditions this will bring an increase in southwest to westerly winds and periods of precipitation. Most of the individual ensemble members of the ECMWF and GFS indicate light precipitation will occur Tuesday into Wednesday. There does remain some uncertainty in timing with the passage of a secondary shortwave sometime Thursday or Friday. Gfs ensemble members show more spread through time with solutions showing light precipitation continuing through Friday. The ECMWF shows more of a distinct dry period for much of Thursday into Friday. The probability of rainfall totals exceeding 0.25" for Tuesday through Thursday is 15 to 25 percent for the coast and valleys; 30 to 60 percent for the coastal slopes of the mountains; and 10 to 15 percent for the High Desert. The low desert is expected to remain dry.
Spread in snow levels has decreased since yesterday with conditions trending in the colder direction. Nbm 25th and 75th percentiles have snow levels between 5000 and 6500 feet respectively for Tuesday through Thursday. Guidance is indicating an inch or two of snow could accumulate, but chances of snowfall totals exceeding 3 inches is about 10 percent. In addition to precipitation chances, gusty southwest to west winds are expected in the mountains and deserts. There are still some uncertainties in the timing and strength of the winds, but strongest winds are likely to occur on the desert mountain slopes and below passes.
For next weekend, the pattern looks to remain unsettled with another upper level trough approaching the US West Coast. This will maintain cooler weather with additional chances of precipitation.
080000z. VFR expected to prevail through the period, though there is a brief window for possible CIGs (less than 15% chance) this evening at KSAN/KCRQ. This slight chance for low clouds (which will likely be near 700ft-1100ft MSL) will close around 06-09z Sunday as weak offshore flow settles in towards the coast, helping to push out any clouds that managed to sneak in.
Westerly swell (280 degrees) at 15-16 seconds has resulted in seas of 6-9 feet in the outer waters near/around San Clemente Island today. This may also lead to localized steep, rough conditions near the bay entrances, including the entrance to the San Diego Bay/Zuniga Shoal area and Oceanside Harbor. Otherwise, no hazardous marine conditions are expected through Thursday.
Increasing long-period (15-16 second) swell from the west-northwest (280 degrees) has resulted in elevated to high surf of 5-8 feet with locally higher sets to 10 feet, continuing through early Sunday morning. Impacts are greatest at west facing beaches, especially across southern San Diego County with a high risk for rip currents. This may also lead to minor tidal overflow for low-lying beach areas overnight. Further information can be found in the High Surf Advisory.
Ca, High Surf Advisory until 6 AM PST Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
