432 FXUS66 KSGX 250344 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 844 PM PDT Mon Jun 24 2019 .SYNOPSIS... An upper level trough will persist over the West this week, maintaining onshore flow and a moderate marine layer. Low clouds will move inland each night and clear back to near coastal areas each day. Some drizzle will be possible again tonight and Tuesday night into Wednesday morning. Slight cooling is on tap through Wednesday, followed by slight warming late in the week, and further inland warming early next week as the subtropical high moves north toward a mid Summer position near the Four Corners. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... ...Patchy drizzle added to coastal and western valley areas again tonight and Tuesday night... The marine stratus was well on it's way through the valleys by 8 PM PDT. The 00Z Miramar sounding had a 6C inversion based near near 1850 FT MSL. This was little changed from yesterday. The sfc pressure gradients (KSAN to the deserts) were all trending onshore and wind-prone desert/pass areas were responding with peak westerly wind gusts of 30 to 40 MPH. Looks like our daytime temps will be running some 5-10F below average through Wednesday, with only partial coastal clearing each day. With a deepening marine layer and ample moisture, a persistence forecast (including patchy drizzle) seems more likely than not, so it has been added for the next couple of nights. From previous discussion... An upper low off British Columbia will move south then eventually east over the Pacific Northwest. This will maintain a large scale trough pattern along the U.S. West Coast. However, across SoCal heights will slowly build, leading to slow warming late this week. An upper ridge will build over the Desert Southwest early next week and will nudge westward into our area. However, the degree of warming is uncertain as we will be on the edge of some shortwave troughing over the eastern Pacific. Indications are that heat will build inland early next week. Whether or not it gets to excessive levels inland will be dependent on the desert ridge placement and strength. Ensembles favor keeping the heat in check, but we'll be watching the trends. && .AVIATION... 250330Z...Coast/Valleys...OVC010-015 tops 023 through Tuesday at KSAN, KCRQ and KSNA. A brief period of SCT015 possible between 22Z- 02Z. Ocnl vis 5 miles at KCRQ. CIGS 010 at KONT and KSBD from 09Z-17Z Tuesday with vis 3-5 miles in fog and haze. After 17Z...skies becoming clear with vis increasing to 6+ miles. Mountains/Deserts...Scattered high clouds above 20kft with unrestricted VIS through Tuesday. && .MARINE... No hazardous marine conditions through Saturday. && .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...10/Gregoria AVIATION/MARINE...Moede