Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
892 FXUS66 KSGX 030410 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 910 PM PDT Tue Jul 2 2024 .SYNOPSIS... A prolonged heat wave will continue into next week for inland areas, with the hottest conditions expected Friday and Saturday. A persistent marine layer will keep temperatures near the coast from soaring. Low clouds and fog are expected to spread into the western valleys each night and morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... High temperatures Wednesday are expected to be a few degrees warmer than today for most locations. Heat is expected to continue for the Fourth of July with highs 3 to 5 degrees above average for the coast and western valleys and 5 to 12 degrees above average for inland areas. Make sure to take seek shade and drink plenty of water if your Fourth of July plans are taking you outdoors. Above average temperatures will continue for most areas through next week as the ridge of high pressure lingers over the Western United States. There is some uncertainty surrounding the position of the ridge axis early next week, with GFS and Canadian ensemble guidance showing the ridge axis more over the Great Basin, while the ECMWF keeps the ridge axis over the West Coast. There is lesser uncertainty in the strength of the ridge, with most guidance indicating that the ridge will weaken slightly by early next week from its peak Friday and Saturday. Major to extreme heat risk will continue in the deserts through next Wednesday. Moderate to locally major heat risk is expected for areas in and west of the mountains. From previous discussion issued at 2 PM July 2... A strong upper ridge develops Wednesday just off the coast and spills into CA and the West through Saturday. And I do mean strong; a lot of guidance shows heights that reach 600 decameters over NorCal Thursday through Saturday. Friday and Saturday right now appear the be the hottest days. Heat warnings are in effect in all desert regions through next Tuesday. Heat Warnings are in effect for mountains and inland valleys Friday and Saturday. Heat Advisories are in effect for inland Orange County and the Santa Ana Mountains Friday and Saturday. This heat wave will be significant and long- lasting even for early July. Temps at night will not cool off much, so the accumulated heat risk will add to the stress on humans. The marine layer will get more shallow for the rest of the week, with less nocturnal coverage, but coastal clouds and fog will not go away entirely. Max temps today through Thursday will range from 2 to 12 degrees above normal, with the greatest anomalies in the desert. On Friday and Saturday, the hottest days, max temps will range from 6 to 15 degrees above normal. That puts Palm Springs up to 122, flirting with the highest temps on record. The 12Z model/ensemble guidance has a slightly better consensus on the ridge beginning to weaken Sunday, but only slightly. This will result in a few degrees of "cooling" for areas west of the mountains with similar to only a degree or two "cooler" for the deserts. && .AVIATION... 030330Z...Coast/Valleys...Areas of low clouds will continue to slowly develop within 5 miles of the coast through 07Z Wed, then spread up to 20 miles inland by 12Z Wed with BKN/OVC bases 800-1300 ft MSL and tops to 1500 ft MSL. Local VIS 1-3 miles will occur in the coastal valleys and higher coastal terrain 08Z-16Z Wed. Most areas will clear 15Z-18Z Wed with slow development of low clouds and fog Wed evening. Mountains/Deserts...Mostly clear skies with unrestricted VIS will continue through Wed evening. Local west sfc winds will occur on the desert slopes and through San Gorgonio Pass with gusts mostly 25 kt or less through 08Z Wed and then again 02Z-08Z THu. && .MARINE... No hazardous marine conditions are expected through Sunday. && .BEACHES... A swell of 2-3 feet from 190 degrees with a period of 16-18 seconds will arrive at SoCal beaches as early as Wednesday morning, peak Friday and gradually subside next Sunday and 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 from Wednesday through next 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 Thursday 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 Tuesday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass Near Banning. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE/BEACHES...Maxwell