A cooling and drying trend will occur across the region into the weekend and early next week. This will be accompanied by a building marine layer with clouds returning closer to the coastal areas each night and morning. An area of high pressure may strengthen by the end of next week, nudging temperatures back above average.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
Nighttime satellite currently shows patchy low clouds caught in the flow of a weak coastal eddy drifting into coastal Orange County. Clouds should eventually fill in over coastal areas overnight with greater inland coverage to the western valleys (and patchy fog) in the following nights.
The ridge that spiked coastal temperatures over the past week continues to move inland into the south central US. This has increased the depth of our marine layer influence to reach into the interior valleys with overnight humidities reaching 80-100% in these lower areas for the next few nights.
Today's temperatures will be similar to yesterday's: upper 70s near the beaches, 80s in coastal areas, low 90s inland, mid-to-upper 90s in the IE and high desert and 100s in the lower deserts.
Sunday's temperatures fall another 3-5 degrees as the trough to the north moving through the PacNW continues to displace the remaining ridge influence from SoCal, restoring near average max and min temperatures region-wide.
There is moderate confidence that cooling continues into Tuesday given the northern trough looks to expand in length and maintain its influence as it moves eastward. Temperatures early week could be a few degrees below average with highs back to the mid-70s at the coast, only reaching to around 90 degrees in the interior valleys/IE/high desert and around 100-102 degrees in the lower deserts. Low temperatures in the interior valleys Tuesday and Wednesday mornings could drop into the mid-50s, offering significantly cooler nighttime air as compared to last week. Elsewhere in the coastal basin, lows will drop into the lower 60s.
Although model uncertainty is higher Wednesday onward, both the GFS and ECMWF show the ridge in the Southern Plains expanding westward, initiating another warming trend to some degree. Inland temperatures may increase once again another 5-15 degrees while there is greater uncertainty for coastal areas as this will depend on the placement of the peak ridge axis.
121130z, Coasts, Very patchy low clouds with bases around 700-1500 ft MSL along the coast. Minor vis reductions (1-5SM) expected along elevated coastal terrain and locally into western valleys. Clouds clear toward the coastline 16-18z with SKC expected for the afternoon. Cigs may redevelop early, 01-03Z Sun, bases will likely be 1000-2000 ft MSL. Vis reductions most likely on higher coastal terrain.
Otherwise, FEW clouds above 15 kft and VFR conditions through Sunday.
West-northwest winds expected to gust up to 20 knots in the afternoons through Sunday over outer coastal waters. Otherwise, no hazardous marine conditions are expected through Wednesday.
Ca, None. PZ, None.
