High pressure aloft will maintain high temperatures through Friday from around 10 degrees above average near the coast to 15 to 20 degrees above average for inland areas. Night and morning coastal low clouds and fog will spread into the western valleys at times. Cooling will begin to spread farther inland next weekend, but with high temperatures for next Sunday still 10 to 15 degrees above average in the coastal areas and inland valleys.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Evening update, The string of record breaking heat continued today with seven locations breaking their daily high temperature records, in most cases by 5 degrees or more.
Marine layer low clouds have returned to parts of the coast this evening but remain patchy off the San Diego County coast. These clouds will fill in overnight, spreading into the far western valleys by sunrise. Even far northwest parts of the Inland Empire have high enough dew points for some light radiation fog to develop early Tuesday morning. Otherwise scattered high clouds will continue to move across the region tonight.
Previous discussion, High pressure ridging over SoCal with a closed upper low off the coast of northern Baja will control our weather through the workweek. The ridge will build over the region through Tuesday as the closed upper low moves to the southwest but by Wednesday the low will move northeastward over SoCal. It will have little impact on conditions at the surface, although there will be minor day-to- day differences in temperature. The ridge will rebuild for Thursday and Friday. The marine layer will play a role in affecting temperatures depending on how far inland the low clouds/fog spread during the nights and mornings and how long it takes for them to lift each morning. The subsidence from the high pressure ridge will keep the marine layer inversion fairly strong so clearing is unlikely to be very early each morning. Daytime high temperatures will range from around 10 degrees above average near the coast to 15 to 20 degrees above average for inland areas. Daily maximum records may be broken or tied in the inland areas but the monthly records are unlikely to be challenged.
For the weekend into early next week, temperatures will trend lower and marine layer clouds and fog will spread farther inland as the high pressure ridge weakens and gets displaced to the southeast as a low pressure trough approaches the coast from the west. Next Monday will likely be the coolest day, with high temperatures mostly 5-10 degrees above seasonal averages.
240430z, Low clouds based 900-1300 feet MSL are developing in coastal areas. Clouds gradually fill into inland valleys and OC 05- 08z, up to 15 miles inland. From 08-16z, patchy FG/BR and vis 0-4SM over coastal mesas and inland OC; 5-6SM (from BR/HZ) for lower coastal areas. Patchy cigs down to 400 ft MSL (and VIS 3-5SM) for coastal TAF sites at times. Bases lift to 800-1500 ft MSL after 13z as vis improves starting around 16z. Low clouds clear to beaches 17- 18Z Tue.
Low clouds with similar bases begin to redevelop at the coast around 23z Tue, filing into coastal areas 02-04z, then to inland areas thereafter (similar extent as tonight).
Otherwise, mostly clear and VFR conditions will prevail into late Tuesday.
No hazardous marine conditions expected through Friday.
Ca, None. PZ, None.
