Persistent high pressure over the region will contribute to warm days with dry weather for the foreseeable future. High pressure will weaken some by the weekend, allowing for slight cooling trend with areas of low clouds and fog each morning by later this week. The area of high pressure will drift southward by early next week, continuing the warmer and drier weather pattern.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Four locations broke their daily high temperature record today, Chula Vista, Ramona, Riverside, and San Jacinto reaching the mid to upper 80s. Palomar Mountain tied their daily high temperature record by reaching 72 degrees. More information on today's records can be found on our weather.gov/sandiego homepage. Highs tomorrow are expected to be 3 to 5 degrees cooler than today for the coast and valleys but a degree or two warmer in the mountains and deserts. There are a few locations in contention for breaking or tying high temperature records tomorrow in the mountains and deserts. Big Bear and Lake Cuyamaca are forecast to reach 65 and 70, respectively, which would tie daily high temperature records. Borrego is forecast to reach 84 degrees which would break the high temperature record.
From Previous Discussion Issued at 2 PM December 10,
There is low confidence in the cloud and fog forecast for the next couple of mornings as the marine layer remains thin. Models suggest patchy fog may form tonight, but confidence remains low on this. As the high slowly weakens overhead, the marine layer will have a better chance to rebuild slowly over the coming days. The best chance for any impactful fog would be by Friday morning. The marine layer will deepen more significantly by the weekend as the high weakens further, with low clouds expected into the western valleys.
Weak offshore flow will continue each afternoon as the high slowly weakens into the weekend, which will bring a subtle cooling trend to our region. Most area west of the mountains in the 80s today will dip into the 70s by the weekend. The area of high pressure will begin to drift southward but assert dominance over the area, bringing a similar weather pattern with warm and dry weather. Ensemble models show this ridging pattern holding on for the foreseeable future, which would continue the dry weather pattern into much of next week.
110415z, There is a 10-20% chance of fog developing near the coast after 07Z, but confidence in fog reaching any of the coastal TAF sites is low. Chances of cigs 500 ft or less and vis 1 mi or less increases to around 30-50% after 12/05Z for the coast and up to 5-10 mi inland. Otherwise mostly clear with unrestricted vis through Thursday evening.
10-20% chance of patchy, intermittent fog development after midnight tonight which may reduce local visibility below 1 NM at times through Thursday morning. Higher chances (30-50%) of fog development Thursday evening into Friday morning and again Friday evening into Saturday morning.
Ca, None. PZ, None.
