Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
699 FXUS66 KSGX 050346 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 846 PM PDT Thu Jul 4 2024 .SYNOPSIS... Hot conditions will continue into at least the middle of next week. The heat will peak on Friday and Saturday for most areas, but above average temperatures will continue for all areas into next week. The marine layer will continue to moderate temperatures near the coast with night and morning coastal low clouds extending into portions of the western valleys at times. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Low clouds redeveloped at the beaches earlier this evening and are beginning to spread a couple miles inland, elsewhere skies are clear. Low-level moisture from the Gulf of California made it into the lower deserts today with dew points at Palm Springs reaching 70 degrees this morning. This moisture didn`t completely mix out as southeast flow prevailed there through the day, limiting heating and keeping the high at Palm Springs at "only" 115 degrees. Local hi-res guidance shows another low-level moisture surge late tonight into Friday morning, however, as the upper high repositions itself low and mid level northeasterly flow should usher in some drier air, allowing for more warming across the entire region. With this in mind, did not do any further downward adjustments for high temperatures tomorrow. Previous discussion... A strong ridge of high pressure will slowly move east setting up over California`s Central Valley by Sunday. This will result in well above average temperatures for inland areas this weekend. The upper level ridge is expected to be it`s strongest Friday and Saturday, which correlates with the peak of the heat for most areas at the surface. The greatest warming on Friday is expected to be in the inland valleys with a couple degrees of "cooling" for inland areas Saturday. Moderate to major heat risk is expected Friday and Saturday for inland Orange County, the valleys, and mountains. The influence from the marine layer will continue to moderate daytime temperatures along the coast. Highs Friday are expected to be a few to 5 degrees warmer than today in the deserts. An additional degree or two of warming is expected on Saturday. Until the ridge becomes more settled over California, there is a potential for morning gulf surges from the Gulf of California to make it into the lower deserts. This could put a cap on how high temperature readings get in the lower deserts Friday through the weekend, but with the moisture increases will make it feel more muggy. Current trend from the guidance is for a gradual drying into early next week. If that drying trend verifies that will allow for more daytime warming to actually occur each day, with the potential for record breaking temperatures in the deserts. Even if the daytime highs are capped by the moisture surges, HeatRisk for the deserts will be major to extreme Saturday and Sunday, continuing into next week. Not quite as hot for the coast to the mountains for Sunday and Monday with not much change for the deserts. There is a small chance of at least a minor influx of monsoonal moisture into the area for the latter half of next week. That would tend to bring warming west of the mountains with high temperatures for the lower deserts not quite as hot depending on the degree of moisture influx. Current forecast follows the NBM closely for the middle to end of next week with an uptick in temperatures for areas west of the mountains Tuesday through Thursday and little change in temperatures in the deserts. Chances of showers and thunderstorms remain 10 percent or less through next Thursday. && .AVIATION... 050330Z...Coast...Low clouds will gradually cover coastal areas overnight, latest for Orange County. Bases will be 700-1000 feet MSL, tops to 1500 feet, with reduced vis 2-5SM in BR over higher coastal terrain 10-16Z. Scatter out Friday 15-17Z. Low clouds to redevelop Friday evening after 03Z with similar bases/vis. Otherwise, mostly clear skies with unrestricted VIS through Friday. && .MARINE... No hazardous marine conditions are expected through Tuesday. && .BEACHES... A long-period south swell will increase the surf, peaking late Friday through Saturday, before subsiding Sunday. Sets of 6-7 feet can be expected on south and southwest-facing beaches, especially in Orange County. Check the Beach Hazards Statement for details. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Sunday afternoon for Orange County Coastal Areas-San Diego County Coastal Areas. Excessive Heat Warning from 11 AM Friday to 9 PM PDT Saturday for Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains-San Diego County Valleys. Heat Advisory from 11 AM Friday to 9 PM PDT Saturday for Orange County Inland Areas-Santa Ana Mountains and Foothills. Excessive Heat Warning until 9 PM PDT Wednesday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...SS/CO AVIATION/MARINE...MM