textproduct: San Diego

SYNOPSIS

Light showers will continue this evening, tapering off overnight. A period of drier weather will occur on Friday. A series of weak but colder weather systems will bring more chances for light to moderate showers over the region for this weekend through the middle of next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

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

Scattered showers continue this evening across San Diego County, with very isolated coverage further north. Any additional accumulation tonight will generally be less than 0.10 inch. CAMs are still showing isolated light showers moving up from the south on Friday, mainly over the coastal areas and valleys. These light nuisance showers could continue into Friday night in moist southwesterly flow ahead of the next system.

An upper level trough digs off the West Coast as a low drops out of the Gulf of Alaska. A leading short wave associated with this trough will lift across CA on Saturday, with most of the precipitation occurring across So Cal sometime late Saturday morning through Saturday evening. NBM mean 24 hr precipitation for Saturday morning through Sunday morning ranges from around 0.15" near the Mexico border to around 0.50" near the LA County border, with amounts up to 1" for the eastern San Gabriel Mountains, and a few hundredths in the deserts. Snow levels will fluctuate between 7,500 and 8,500 ft during this period.

This is followed closely by another short wave Sunday afternoon into Monday, which ensembles are producing slightly higher precipitation amounts for, but still nothing close to what we saw today. NBM probabilities of 1" or more for Sunday morning through Tuesday morning are only around 10-15% for Orange County and the mountains (up to 45% for the eastern San Gabriels), and less than 10% elsewhere. Snow levels finally drop to 6,500-7,000 ft by Monday morning, so we may start to get some accumulations in the mountain communities.

Ensembles start to diverge in the track of the main trough/upper low later Monday into Wednesday. Around 23% of the members keep the trough as a more progressive open wave, while the remaining members dig it further south and try to close it off, resulting in a slower eastward progression. The latter would delay the onset of precipitation with the next wave, allowing for more of a break in precipitation between the Sunday/Monday and Wednesday-ish system. There is even the potential for this system to dig so far south that we get little to no precipitation, especially for the northern areas. Needless to say, confidence is low in timing, amounts, and snow levels with this system.

Another trough is forecast to move inland across the Western US on Thursday into Friday. Ensembles vary in the depth and timing of this trough, but mostly agree on a somewhat inside track which would limit the precipitation chances in So Cal - currently around 15-25% on Thursday. Otherwise near to slightly below normal temperatures through Saturday followed by cooler weather with highs 5-10 degrees below normal each day through Thursday.

AVIATION

020400Z...Isolated -SHRA still lingering in San Diego County may create minor vis reductions (4-6SM) over the next few hours. Otherwise, BKN clouds based 3000-5000 ft MSL will continue to slowly rise overnight, becoming FEW-SCT at times. Mid level cloud cover increases again Friday afternoon and evening from the coast to the mtns with a slight chance -SHRA, highest in Orange County. Coverage becoming mostly BKN Friday evening and overnight with bases lowering to 2000-3000 ft MSL 00-06Z Sat.

MARINE

No hazardous marine weather conditions expected through Monday, though there will be periods of breezy south winds through the weekend.

BEACHES

High tides of 6.5 to 7 feet this weekend could lead to minor coastal overflow/flooding for beaches and flood-prone beach lots and walkways.

SKYWARN

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

SGX WATCHES/WARNINGS/ADVISORIES

CA...Beach Hazards Statement through Sunday morning for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.