Area forecast discussion National Weather Service San Diego California 900 am PDT Friday may 24 2013 Synopsis... daytime temperatures will remain slightly below seasonal averages through Memorial Day...with only minor day-to-day variations. Onshore flow with gusty winds in the mountains and deserts will also continue...along with areas of low clouds extending into the inland valleys during the nights and mornings. For Tuesday through early Wednesday...increasing clouds with even lower temperatures and a chance for precipitation. Dry and warmer for Wednesday and Thursday with stronger northwest winds in the mountains and deserts. && Discussion...for extreme southwestern California including Orange... San Diego...western Riverside and southwestern San Bernardino counties... This morning...low clouds are clearing out of San Diego County but extensive clouds remain over Orange County and the inland Empire. Surface pressure gradients remain onshore...but are trending weaker with +1.5 mb san-tph. The morning nkx sounding shows the marine layer about 3400 feet deep with southerly winds near the surface and west winds above a weak inversion. Through Memorial Day...the large-scale low/trough over the West Coast will maintain the onshore flow for gusty west winds in the mountains and deserts. Daytime temperatures will continue to be a little below seasonal averages...and the marine layer will remain relatively deep with night and morning low clouds extending into the inland valleys. Small day-to-day variations in the marine layer depth are expected as minor shortwaves move through the mean cyclonic flow aloft. For late Monday night through Tuesday night...a stronger shortwave moving through the northwest flow aloft...is expected to deepen the trough...forming a closed upper low over central California by Tuesday morning. There is not yet a clear consensus among the deterministic models as to the exact timing and track of the low as it progresses eastward through Tuesday night...and the individual models continue to make minor adjustments to their various solutions. However...confidence is growing that this system could produce rain and showers late Monday night through Tuesday night. Preliminary rainfall estimates are for one tenth to one quarter inch near the coast and one half to one inch in the mountains. Dry and gradually warmer for Wednesday through Friday in northwest flow aloft as the trough moves east and heights rise over socal. This will bring stronger...gusty northwest winds in the mountains and deserts and a shallower marine layer. && Aviation... 241600z...coast/valleys...areas of few-scattered stratus will continue west of the mountains with bases 2500-3500 feet mean sea level and tops to 4500 feet mean sea level through the remainder of this morning into the late afternoon. Visible will remain p6sm. Stratus returning tonight between 25/0200-0400z. A weaker coastal eddie and slightly higher pressure aloft will lead to a cloud deck a couple hundred feet lower than this mornings. Bases around 2500 feet and tops near 3500 feet. Visible is expected to remain above 5sm. Mtns/deserts...westerly wind gusts around 35 knots will occur over the Desert Mountain slopes and through/east of San Gorgonio Pass late this afternoon/this evening. Otherwise...mostly clear with unrestricted visible through Saturday afternoon. && Marine... astronomical high tides to 7.2 feet and below normal low tides...with swings of 8.9 feet...will combine with slightly above normal surf to bring a small chance of minor coastal flooding today through Memorial Day. Strong rip currents will continue through Memorial Day...partly due to the swings in The Tides. && Sgx watches/warnings/advisories... California...none. Pz...none. && $$ Public...pg aviation/marine...jt