Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
810 FXUS66 KSGX 102051 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 151 PM PDT Fri May 10 2024 .SYNOPSIS... There is a slight chance of showers over the San Bernardino and Riverside County mountains this afternoon and evening. Areas of night and morning low clouds and fog will continue across portions of the coastal areas and valleys through the week. Gradual warming inland through Sunday followed by minor cooling Monday and Tuesday. Inland warming trend will resume on Wednesday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Low clouds have stubbornly hung on in coastal San Diego County early this afternoon, and it doesn`t look so good for clearing today. Low clouds have cleared elsewhere just fine. Cumulus clouds have accumulated in the mountains and deserts, but so far they haven`t grown tall enough to produce showers. A weak upper level trough sits over the West today, with a wave of mid-level moisture and instability rotating through inland SoCal. This feature is the cause of the cumulus clouds over the mountains and deserts, leading to a slight chance of showers to the higher mountains through early evening. The trough begins to weaken and move out over the weekend, but with lingering moisture and some clouds over mountains in the afternoon. The trough`s departure will bring us a warming trend, and a shallower marine layer for less nocturnal cloud/fog extent Sunday into Monday. A new weak upper low from the northwest will float harmlessly across SoCal Monday and Tuesday, which should deepen the marine layer and extend the coastal clouds. Today we`ll have max temps a few degrees below normal except inland valleys should reach a little above. We warm up this weekend, so that by Sunday max temps should be 0-8 degrees above normal. The 0-degree difference representing the coast and the 8-degree difference in the low desert, probably hitting 100 degrees in spots. For the second half of next week, there is unsurprisingly a large spread in ensemble guidance. An amplified high-pressure ridge develops over the West, but with a weak low-pressure trough directly south of it, what we call a Rex Block. SoCal lies within the lower pressure embedded under the strong high pressure, so the forecast picture gets wishy-washy. A slimming minority of members indicate some low pressure and moisture leading to showers, but the vast majority of members keep our weather dry and seasonal. For now our forecast Wednesday through next Friday is dry with a warming trend, a typical medium strength marine layer, and temperatures near normal at the coast and a few degrees above normal inland. && .AVIATION... 102045Z...Coast/Valleys...Areas of low clouds with bases 1800-2200 ft MSL and tops to 3000 ft with local VIS 1-4 miles in BR, mainly in the southern coastal areas. Local terrain obscurations in clouds. Mostly clear northern coastal waters and valleys. After 11/02Z low clouds moving onshore and inland...pushing east past KONT and KRNM late tonight. Mountains/Deserts...SCT/BKN clouds over the mountains with bases around 2000 ft MSL with local TCU possible. Otherwise, mostly clear skies will prevail through this evening with unrestricted VIS. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...MM AVIATION/MARINE...Small