textproduct: San Diego

SYNOPSIS

Cooler conditions expected for much of this week. Increased winds and periods of precipitation expected for the middle the week. Dry conditions expected to return for Friday and Saturday with increased chances of precipitation and winds for early next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

At noon, temperatures were trending anywhere from a few degrees warmer than yesterday to up to 15 degrees warmer than noon yesterday. Breezy easterly winds were gusting to 20 to 30 mph below major mountain passes and on coastal foothills of the mountains. Those winds will weaken into this evening. The upper level pattern begins to shift Monday, bringing a few degrees of cooling across the area and the return of weak onshore flow. Further cooling is expected into Tuesday as troughing develops over the US West Coast.

Dry conditions are expected through much of Tuesday, with increasing confidence that a shortwave will move through the mean flow early Wednesday. A band of precipitation is expected to move northwest to southeast across the area starting early Wednesday morning and tapering off by the afternoon. Light to moderate rain is expected in the rain band. Latest forecast keeps total rainfall 0.25" or less for the coast and valleys and 0.30-0.50" for the coastal slopes of the mountains. NBM probabilities of total rainfall exceeding 0.25" from Tuesday morning to Thursday morning are highest in Orange County (30-40%) and the San Bernardino County mountains (50-70%). Light rain is possible again sometime Thursday into early Friday as the long-wave trough progresses eastward. NBM probabilities for rainfall totals exceeding 0.10" from Thursday morning into Friday morning are 10-20% for the coast and valleys and 20-30% for the coastal mountain slopes.

Snow levels during the highest chance of precipitation Wednesday are expected to be 6000-6500 ft. Latest forecast has 1-3" of snow from Tuesday night through Thursday, with totals at the higher end of that range expected at 7000+ feet. NBM chances of snowfall totals exceeding 3 inches is about 10 percent. In addition to rain and snow, gusty southwest to west winds are expected in the mountains and deserts. Strongest winds are likely to occur on the desert mountain slopes and below passes Tuesday afternoon into Wednesday. Current forecast has peak wind gusts of 40 to 50 mph.

Weak transitory ridging follows the upper trough for Friday afternoon into Saturday, bringing a brief period of dry and slightly warmer weather. A more robust trough dropping out of the Gulf of Alaska will bring additional chances of precipitation and gusty winds beginning as early as Saturday evening. Wet and cool weather will likely continue into much of the following week with the potential for much higher rain and snow amounts.

AVIATION

090000Z....VFR conditions and clear skies expected through the TAF period. Onshore flow with largely northwesterly winds persisting this afternoon become lighter and weakly offshore overnight. Low clouds may develop off the southern San Diego County coast overnight, but the weak offshore flow will keep any clouds over the waters.

MARINE

Northwest winds gusting near 15 knots in the outer coastal waters near San Clemente Island this afternoon and early evening. Otherwise, no hazardous marine conditions are expected through Friday.

BEACHES

Swell and associated elevated surf is winding down this afternoon, with most sites now reporting max sets at or below 6 feet. Surf will continue to fall through tonight.

SGX WATCHES/WARNINGS/ADVISORIES

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