textproduct: San Diego

SYNOPSIS

Patchy low clouds and fog possible near the coast this morning and again tonight. Warm and dry 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.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

A few thin patches of fog are developing over the coastal waters this morning with clear skies elsewhere. Surface dew points have been trending downwards along the coast with weak drainage flow, so chances of fog forming right along the coast are diminishing. The HREF has a 20-40% 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 East Pac will strengthen but remain relatively stationary through Tuesday, then weaken slightly as it shifts eastwards over Western US through the end of the week. At the surface, persistent surface high pressure over the Great Basin will drive Santa Ana winds across So Cal through Saturday. Gradual warming takes place through Tuesday with the strengthening winds and increasing offshore flow, when highs will be as much as 10-20 degrees above normal. Widespread highs in the low to mid 80s is 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 25-40 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 10-15 degrees above normal inland. Ensembles are now showing another peak in Santa Ana winds on 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 8-13 degrees above normal inland.

AVIATION

070930Z....Chances for low clouds and fog development along the coastal locations have gone down from earlier with San Diego seeing chances of less than 10% and Orange County at 10-20% through 18Z this morning. Low clouds seem to be keeping their distance and staying out over the water for the time being. Chances begin to increase after 01Z Monday for patchy fog and low cloud development along the coast with the highest chances occurring after 04Z for San Diego County and after 09Z for Orange County through 18Z. Until then, VFR conditions are expected for all TAF sites.

MARINE

Still a 10-20% chance of dense fog with visibility 1 nautical mile or less developing this morning through 11 AM.

BEACHES

Morning high tide is predicted to be 6.5 around 10 AM this morning. Astronomically high tides may result in tidal overflow in normally dry beach areas. High tide is predicted to fall below 6 ft by Monday.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...None.