A Pacific storm will continue impact the region, producing scattered showers through tonight, some showers could produce locally heavy rainfall at times. Intermittent showers can be expected on Sunday with periods of sunshine. Another weaker system will move through the area on Monday and Tuesday, bringing another chance of rain showers as well as greater snowfall for resort communities. An additional storm system will approach the region by next Thursday and Friday, but forecast details remain uncertain.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
The low pressure system centered to our west is beginning to move east. The bands of widespread rain - heavy at times - have moved to the east with the frontal boundary. Behind the boundary in the colder air, scattered showers are moving from southwest to northeast across the region. These showers will mostly be light but have the potential for brief, locally heavy downpours. Additional rainfall amounts from tonight through Sunday evening will range from one third inch to three quarters inch in the coastal areas and inland valleys. The mountain slopes could receive an additional 1-1.5 inches and the deserts a few hundredths.
The strong southerly winds associated with the frontal bands have also moved east into AZ and at this hour, winds are mostly gusting to 20 mph or less. There were several lightning strikes this afternoon over the lower deserts but those thunderstorms have also moved east. One lightning discharge was detected in the last hour and it was over Los Angeles County. Additional strikes will be possible through tonight. There could be a brief period without rainfall Sunday evening/night as a dynamic ridge of high pressure between the low pressure systems moves over the region.
From previous discussion, The storm system will move northeastward through Sunday over our region, where leftover light to moderate showers will continue off and on for areas mainly along and west of the mountains. Like the forecast for tonight, some of these storms may produce rain rates near one half inch/hour.
A low pressure system currently in the Gulf of Alaska will move down the coast over the weekend, pushing into Southern California by Monday and Tuesday. Model guidance is in better agreement on the timing of this system producing a line of light to moderate intensity rain showers by late Monday morning into the afternoon moving from west to east. Though there is still some uncertainty on exact rainfall totals, confidence is high that these will be much less than those of this weekend. This system will also be colder, dropping 850 mb temps closer to 1-3C, so snow levels are expected to go down somewhere near 5,500 feet. This will yield a greater chance for areas like Big Bear to see accumulations greater than 1 inch. The coldest part of the system will move into our region on Tuesday, with highs staying in the 30s/40s across the mountains, with 50s/60s elsewhere.
A brief drier and sunnier day is expected by Wednesday as the early week system departs. Model guidance begins to diverge on an additional storm system moving into the region by later next week. Model guidance begins to diverge on the potential for yet another storm system to move into the region later in the week. Confidence is low on the exact placement of this storm system and exactly where/if we receive any precipitation from this. Model ensembles show about one half to two thirds of members showing measurable precipitation for those along and west of the mountains, so stay tuned as we iron out the details.
150500z, Patchy -RA and scattered SHRA continue across coastal basin. Main BKN-OVC layer at 3000-3500 feet MSL with SCT layers beneath. BKN-OVC 1500-2500 feet MSL in RA/SHRA. VIS generally greater than 6SM, locally 2-6SM where there is rain and 0-2SM where clouds intersect terrain. SHRA to continue this evening with same cloud bases and VIS reductions as tonight.
Between 08-16z Sun, more intense RA/SHRA along the coasts and valleys along with breezy southeast winds bringing lowered bases and reduced VIS, with high res guidance indicating highest chances in SD County for impacts.
After 20Z Sun, -SHRA becomes more isolated, though continuing through the evening.
WSW gusts 25-40 kts continue over mtns and desert slopes through tonight. Desert sites to continue to have VCSH with the occasional SHRA making it over the mountains and briefly reducing VIS/cigs.
Another round of heavier SHRA along the coasts and valleys along with breezy southeast winds possible between 08-14Z Sun, bringing lowered bases and reduced VIS, with high res guidance indicating highest chances in SD County for impacts. Continued SHRA activity for the coastal basin through the day Sunday.
Organized lines of showers will accompany south winds at 15-20 kts and choppy seas tonight and Sunday morning. Seas 5-7 feet throughout the coastal waters lower significantly by Sunday morning.
Winds strengthen again Monday afternoon ahead of the next storm system. There is still some uncertainty in exact intensity of winds, but gusts in excess of 20 knots are possible along with another round of precipitation.
Elevated surf 4-6 feet with sets to 7 feet continue for west facing beaches, though reduce gradually overnight. Surf becomes elevated once more with an additional storm system late Monday into Tuesday.
Ca, None.
PZ, None.
