Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
721 FXUS66 KSGX 041035 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 335 AM PDT Thu Jul 4 2024 .SYNOPSIS... A long-duration heat wave will continue for inalnd areas into next week. High temperatures will be above average for all areas into next week with Friday and Saturday the hottest days for most areas with high temperatures 10 to 15 degrees above average for inland areas. The marine layer will continue to moderate the daytime warming toward 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... .SHORT TERM (Today through Friday)... The long-duration heat wave for inland areas will continue as high pressure aloft over California strengthens. High temperatures today will be a few degrees warmer than Wednesday for the deserts with not much change elsewhere. Friday will be several degrees warmer with the greatest warming for the inland valleys. The hottest high temperatures on Friday for the lower deserts will be around 120, and 112 for the Inland Empire and Apple and Lucerne Valleys. For Saturday, slight warming for the deserts with slight cooling for inland valleys. On Wednesday morning, there was a shallow influx of lower level moisture into the Coachella Valley. The dewpoint at Palm Springs increased into the lower 60s Wednesday morning, then fell into the mid 40s during the afternoon with daytime mixing. That`s in contrast to dewpoints in the lower 30s on Tuesday afternoon. The influx of that moisture was enough to reduce high temperatures a few degrees from what would have otherwise occurred absent the moisture influx. That type of moisture influx could occur today to a more limited extend with NBM showing a lower level drying trend for Friday and Saturday. This should allow more of the potential daytime warming to be realized each day. The marine layer will continue to moderate the daytime warming toward the coast with night and morning coastal low clouds extending into portions of the western valleys at times. && .LONG TERM (Sunday through Wednesday) Not quite as not for the coast to the mountains for Sunday and Monday with not much change for the deserts. There are at least small chances of at least a minor influx of monsoonal moisture into the area 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. NBM has 24-hour chances for measurable precipitation at Big Bear near 10 percent on Friday of next week and 20 percent on Saturday. For Palm Springs, NBM has at least a 60 percent for high temperatures of at least 120 each day for Friday through Tuesday, greatest on Saturday at 90 percent. NBM chances to at least tie the all-time record high temperature of 123 at Palm Springs are greatest on Saturday and again on Monday at 24 percent. Chances to break the record are greatest on Saturday at 14 percent followed by 13 percent on Monday. && .AVIATION... 040930Z...Coast/Valleys...BKN-OVC low clouds at 700-1200 ft MSL will stay within 15 miles of the coast through the morning, locally SCT conditions at SD Co TAF sites as well. Local VIS will be 1-3 SM in BR in some valleys and higher coastal terrain, with local obscurations possible. Clouds clearing toward the coast with moderate confidence in timing between 16-18Z, though some areas of BKN cigs may linger into the afternoon hours near 1200 ft MSL. Low clouds redeveloping and pushing inland after 03Z Fri with similar bases as this morning. Mountains/Deserts...Mostly clear skies with unrestricted VIS will continue through this evening. Local west sfc winds 20-30 kt will occur through San Gorgonio Pass 00Z-12Z Fri. && .MARINE... No hazardous marine conditions are expected through early next week. && .BEACHES... Long-period south swell (2-3 feet/16-18 seconds/190 degrees) will build later today, peak Friday and Saturday, then gradually subside on Monday. This will lead to elevated surf with breaking wave heights up to 7 feet, mainly on exposed south and southwest-facing beaches in Orange County. Rip and longshore current risks will be high as well through Monday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement from 11 AM PDT this morning 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...17 AVIATION/MARINE/BEACHES...APR