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,
.Evening Update,
Patchy low clouds have cleared off the coastal areas this evening, where the area will remain clear throughout the night with thin high clouds above the rest of SoCal. A brief ridge of high pressure still looks to graze the region on Sunday with warmer weather. The chances for high temperatures to reach over 85 degrees are around 30-50% across east county San Diego and the western half of Orange County (e.g. Santee, Anaheim). Chances in the Coachella Valley increase for the eastern end of the valley (60-80%), notably Indio to Mecca. Weather pattern change looks on track for the upcoming week. Slight chances for showers remain Tuesday through Thursday, but would not be surprised for much of the area to remain dry later on Wednesday through Thursday per latest model guidance.
Previous Discussion (1235 PM Saturday),
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.
080600z. VFR expected to prevail through the period. Satellite shows fully clear low/mid levels with just some high cirrus clouds AOA 20,000ft streaming in from the north. Weak offshore flow overnight will prevent any low clouds that may form over the water from moving ashore.
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 earlier 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. This swell peaked earlier today and will continue to wane into Sunday morning. Otherwise, no hazardous marine conditions are expected through Thursday.
The long-period (15-16 second) swell from the west-northwest (280 degrees) which has resulted in elevated to high surf of 5-8 feet with locally higher sets to 10 feet on west facing beaches, has been gradually waning this evening, and will continue to decrease into Sunday morning. The High Surf Advisory remains in effect until 6 AM PST Sunday morning and contains more information.
Ca, High Surf Advisory until 6 AM PST Sunday for Orange County Coastal Areas-San Diego County Coastal Areas.
PZ, None.
