Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
372 FXUS66 KSGX 252043 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 143 PM PDT Wed Sep 25 2024 .SYNOPSIS... Minimal day to day changes in the weather pattern will be expected through the weekend. Temperatures and the marine layer depth will subtly fluctuate as we become under the influence of high pressure to the east and a weak area of low pressure to the west. Slightly warmer weather can be expected by early next week, with a more significant cooling pattern and deeper marine layer occurring by the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A weak trough to our southwest is currently displaced by an amplified ridge across the southern Rockies. The ridge will continue to dominate much of our weather pattern with above normal temperatures from the coastal foothills into the deserts, while a thinner marine layer will keep areas west of the mountains near to slightly below average through the weekend. The high will move slowly westward centering over Arizona by the weekend, where deserts will see a slight bump in temperatures. Chances of seeing temperatures over 110 degrees by Friday and Saturday in the lower deserts is currently 30-60% per NBM, with Saturday being the hottest day over all. Chances are similar for areas of the high desert reaching over 95 degrees during this time period. The high`s movement will also suppress the marine layer, so patchy fog will be more common near the coast into western valleys. Latest ensemble models show the weak low pressure moving over us by Sunday, leading to temperatures dropping off a few degrees area wide. The high to our east will build in with another high off the Pacific coast by next Monday and Tuesday, leading to another slight warm up with highs nearing the century mark across the Inland Empire and foothills in San Diego County. This warming looks to be short-lived though, as latest ensemble model clusters reveal good agreement on a trough dropping in from the north. This will cool us off some, but how cool we will go remains uncertain as the positioning and strength of said trough is still in question at this time. && .AVIATION... 252030Z...Coasts/Valleys...Low clouds have been persistent along the immediate coast this afternoon, with only intermittent or partial scattering, especially along the San Diego County coast. Bases vary between 1000-1500 ft MSL, with tops to 1800-2000 ft MSL. Coastal sites could briefly scatter out this afternoon 21-23Z, but low clouds will start to move back inland after 23-01Z and into western inland valleys overnight, reaching about 20-25 mi inland. Bases will likely lower slightly this evening to 900-1300 ft MSL. Vis reduced 0- 5SM locally in valleys and higher coastal terrain. Low clouds mostly scattering out to beaches 16-18Z Thu, but cigs again look to be persistent along the beaches and immediate coast Thu afternoon. Mountains/Deserts...Mostly clear today and tonight. && .MARINE...No hazardous marine conditions are expected through Monday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning from 10 AM Friday to 8 PM PDT Saturday for Coachella Valley-San Diego County Deserts. PZ...None. && $$ PUBLIC...APR AVIATION/MARINE...CSP