SAN DIEGO (KGTV) — Patchy low clouds and fog are possible near the coast this morning and again tonight. Warm and dry conditions will continue through the week with periods of weak to locally moderate Santa Ana winds. Tuesday will likely be the warmest day with temperatures 15 to 20 degrees above seasonal averages in the inland valleys.
A few thin patches of fog are developing over the coastal waters this morning with clear skies elsewhere. Surface dew points have been trending downward along the coast with weak drainage flow, so chances of fog forming right along the coast are diminishing. There's a 20 to 40% chance of dense fog over the coastal waters tonight into Monday morning, but coverage of any fog would be sparse.
The upper level ridge of high pressure over the Eastern Pacific will strengthen but remain relatively stationary through Tuesday, then weaken slightly as it shifts eastward over the Western U.S. through the end of the week. At the surface, persistent surface high pressure over the Great Basin will drive Santa Ana winds across Southern California through Saturday.
Gradual warming takes place through Tuesday with the strengthening winds and increasing offshore flow, when highs will be as much as 10 to 20 degrees above normal. Widespread highs in the low to mid-80s are forecast across the inland coastal areas into the valleys as well as the low deserts.
With winds being purely gradient-driven, they will be confined to the usual passes, canyons and coastal slopes each night through early afternoon. The first peak in the winds is still forecast to be on Tuesday, though models have trended weaker with peak gusts now around 25 to 40 mph in the wind-prone areas.
Weaker Santa Ana winds and the weakening high will allow for minor cooling Wednesday and Thursday, though highs remain around 10 to 15 degrees above normal inland. Another peak in Santa Ana winds is forecast for Friday, when surface pressure gradients are now forecast to be strongest this week. This will bring another bump up in high temperatures, mainly west of the mountains with highs once again nearing 20 degrees above normal in the valleys.
Nights and mornings will remain cool, especially in the wind-sheltered areas, minimizing any heat impacts. The upper ridge continues to weaken next weekend, and weak offshore flow on Saturday will transition back to onshore flow on Sunday, bringing slow cooling through the weekend. By Sunday high temperatures will "only" be 8 to 13 degrees above normal inland.
