A weak storm system will move through the area later today into early Wednesday. This will bring light to moderate rain showers and accumulating snowfall in the mountains. There will be a brief lull in the action on Wednesday, with sunnier but continued cooler weather. Yet another winter storm system will move closer to the region later on Thursday through at least Friday night, bringing another round of rainfall and higher elevation snow. Things look to dry out sometime early next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
An area of low pressure has moved into Northern California, where an associated frontal boundary continues to move through Southern California. Light showers have been noted so far from LA to Ventura. Showers may increase in intensity through the afternoon and evening hours over our region as hi-res models indicate. Hourly rain rates will peak around 0.50"/hr, but most rates will be closer to one quarter of an inch. We are not expecting too many impacts with this but areas that flooded from the weekend or any other low lying/poor drainage areas may see localized ponding or flooding. This system will be colder than the last, so snow levels near 7,000 feet to start but lower near 5,000 feet by Tuesday evening. A Winter Weather Advisory has been issued for areas in the San Bernardino County mountains above 6,000 feet. A general 2-4 inches is expected around this elevation with locally over 5 inches for areas over 7,000 feet through Tuesday evening.
The exact track of this low pressure system is being a bit more resolved in the models, where the low will move directly over our area. This will provide a better chance of thunderstorms as the cold core moves over the region, so areas mainly west of the mountains will see continued isolated showers and thunderstorms into the day on Tuesday. There will be intermittent breaks in the clouds west of the mountains throughout the day with sunnier conditions in the deserts. Tuesday will be a chillier day as well, with highs 10-20 degrees below average. By Wednesday, the track of this system starts to diverge in the model guidance. Some show the system going far enough south, giving us sunnier and drier conditions. Others show a more interesting scenario, where the backside of the low will produce more precipitation along the mountains into the deserts. We will continue to watch this, as this could produce additional desert rain and mountain snowfall.
The weather pattern continues to remain interesting as we move into Thursday and Friday. Yet another area of low pressure looks to move into the Southern California vicinity, where the probability of rain and mountain snow increases once more. The exact track and precipitation timing / amount details still somewhat uncertain, though compared to yesterday, the model guidance is in better agreement on the system moving over the area or off the coast, which would give us a wetter weather setup. This will solidify a cooler and cloudier weather pattern through the work week. High pressure off the coast looks to move into the region sometime early next week (Sunday or Monday), where drier and warmer weather will move into the region.
172130z, FEW-SCT low clouds based 2-5 kft will increase in coverage this afternoon along with increasing southerly flow. A frontal precipitation band arrives from the northwest starting in Orange County around 01-02Z Tue, reaching San Diego by 05-06Z, and pushing over the mountains and into the low deserts by 09-11Z. Expecting a few hours of cigs 800-2000 feet MSL and vis 1-4SM through the coastal basin with the passage of this band. Slight chc (10-15%) TSRA. Cigs/vis lift and/or scatter out with generally VFR conditions, thereafter. Higher terrain obscured in FG/RA during the frontal passage and through the overnight hours. SCT -SHRA/SHRA begins to develop 12-18Z Tue, reintroducing the threat for intermittent MVFR cigs/vis through the coastal basin. Slight chc (10- 15%) TSRA after 18Z.
A cold front will west to east across the coastal waters from 00-06Z Tue with a distinct wind shift from south to west-northwest. Wind gusts behind the front may reach 20-25 knots through 10Z. Check the Small Craft Advisory for details.
There is a slight chance of thunderstorms this evening along the cold front, and again Tuesday afternoon. Any thunderstorm could produce lightning, gusty erratic winds, choppy seas, and/or a waterspout. No hazardous marine conditions are expected Tuesday night through Thursday, but the next storm system has the potential to bring hazardous winds and seas Thursday night and Friday.
Ca, Winter Weather Advisory until 10 PM PST Tuesday for San Bernardino County Mountains.
PZ, Small Craft Advisory until 2 AM PST Tuesday for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm- Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
