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Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
147 FXUS66 KSGX 111635 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 935 AM PDT Sun Aug 11 2024 .SYNOPSIS... Slightly cooler today with continued chances of thunderstorms over the mountains and deserts. Lower thunderstorm chances on Monday with any activity limited to the mountains and southern deserts. Drier with near normal temperatures Tuesday through the end of the week. Patchy low clouds and fog will gradually increase for the coastal areas each night and morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Coastal low clouds never made their presence felt over land this morning, probably discouraged by the easterly flow aloft from our inverted trough aloft. This trough continues to bring in monsoonal moisture today and chances of thunderstorms for mountains and deserts. It looks quite unstable and humid, so we should get at least several decent storms this afternoon and early evening. Any storm would produce frequent lightning and could produce flash flooding and strong, gusty winds. Elsewhere it should be mostly sunny with a hampered marine layer. A coastal eddy today should help repair the marine layer, so coastal low clouds should make an earlier comeback late today and tonight. Temperatures will start to moderate today from those highs yesterday. The potential temp rise is literally dampened by the low level moisture intrusion this morning. So not so hot, but more muggy. The inverted trough overhead today will fade as a low pressure trough off the Pac northwest coast will amplify over the next couple days. This will effectively sweep away the monsoonal moisture, but enough residual moisture and instability remain over southeastern mountain/desert portions of our area for a slight chance of tstorms Monday afternoon. The amplifying trough to the north will help rebuild the marine layer and boost winds through mountain gaps into deserts during the afternoons and evenings. Temps will settle down to around normal. Coastal clouds will become more uniform, extensive and longer lasting, but still restrained to nights and mornings. Expect these seasonal and dry conditions to remain with very little day to day variation this entire week. && .AVIATION... 111530Z...Coast/Valleys...Mostly clear skies with some FEW-SCT clouds near 20K ft MSL. Low clouds based near 700-1100 ft MSL offshore with tops near 1200 FT MSL locally impacting coastal areas with local VIS 3-5 miles. ISO TSRA drifting into foothills and adjacent valleys west of the mountains this afternoon with the highest chance in SD County. Low cloud coverage confidence higher (50-70%) in cigs reaching coastal TAF sites later tonight, mainly after 06Z Mon based near 1000 ft MSL with tops to near 1500 ft MSL. Mountains/Deserts...SCT-BKN clouds with bases around 10,000 ft MSL develop after 16Z, followed by scattered TSRA between 19Z Sunday and 03Z Monday. Gusty and erratic winds possible near storms as well as MOD UDDFS. && .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