Marine Weather and Tide Forecast for San Jacinto, CA

DISCUSSION
FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

Update: Showers are continuing to dissipate and come to an end at this hour. This will lead to skies clearing tonight, which may allow for some patchy fog to develop within some of the inland valleys where there is sufficient radiational cooling under clear skies and where there is antecedent soil moisture given the recent rainfall today. Temperatures will continue to be on the cooler side for tomorrow, although slightly warmer from where they were today. Guidance suggests that there will still be a slight chance of showers developing over the mountains as some weak instability aloft moves over as the decaying low north of the region propagates southward and over SoCal throughout the day tomorrow.
As far as the rest of the forecast, it still remains on track with a fairly good agreement showing a deepening shortwave moving into the region, with the main brunt of precipitation moving in by next Monday morning. After the first initial shortwave moves through, there is more dispersion between the deterministic models, although the pattern looks to remain unsettled with a broad longwave trough remaining in place over the western states.
This will provide continued cool conditions with chances of rain for most of next week.

Previous discussion submitted at 122PM:

Showers across the region have become lighter over the past few hours. Winds continue to decrease as well, with gusts across mountain desert slopes near 25-40 MPH. Showers will continue to become more isolated through the afternoon hours. Low clouds continue to depart the region toward the southeast, where brighter conditions are being seen closer to the LA County line. A low pressure system over the Bay Area will move southward over the region by Thursday into Friday morning. The system will be weak and moisture starved, so rain chances are low. If any rain falls, it would be over the mountains or the lower deserts. Though the troughing pattern will remain over us, temperatures will slightly warm with highs near average. High temperatures will be in the 60s west of the mountains with highs 50s/60s in the mountains. The trough passes to the east later on Friday into Saturday, and will be replaced by a weak ridge. This will bring sunnier and slightly warmer weather with highs near to slightly above normal.

Models continue to hone in on a large area of low pressure moving down the West Coast. This system will bring a better chance for more widespread rainfall and mountain snow. Timing of models shows some spread on the exact start timing of the precipitation on Sunday. As of now, light showers ahead of the storm would start early Sunday morning across the LA Basin and into the afternoon hours further south and east. The exact path of system will be crucial to exact rain and snow amounts, and right now, that still remains to be seen as models begin to show differences. NBM points to around a 65% chance in seeing rainfall over 1" over populous areas of Orange County, where this chance goes down to 15% from Monday-Wednesday.
Chances go down slightly into western San Diego County. A weak atmospheric river associated with this system will move through the area on Monday, where the heaviest precipitation is expected.
IVT values from models depicts values near 400-500 kg/m/s. This will bring an increased flood threat for areas along and west of the mountains, especially along the coastal slopes. While exact snow amounts remain uncertain, snow levels will be closer to 6,000 feet, bringing areas of heavier snowfall to areas like Big Bear Lake.

The troughing and active weather pattern looks to stick around by Tuesday into the middle of next week. Model details are not as defined, but a series of troughs may move in from the north to provide more chances for rain and mountain snow. NBM chances for precipitation are moderate to high by Tuesday into Wednesday of next week. Next week will also feature cooler weather with highs up to 10 degrees below normal and windier conditions, especially in the mountains and deserts.

AVIATION
120400...Current satellite imagery shows that high clouds have mostly departed the region to the east. Expecting generally VFR conditions through the period. However, patchy low clouds based 2000- 3000 ft MSL will linger through tonight in the coastal basin. SCT- BKN high clouds AOA 20 kft return after 12Z Thu.

MARINE
No hazardous marine conditions are expected through Sunday.

BEACHES
Strong westerly swell (260-280 degrees) with a 11-12 second period will lead to elevated surf of 3-6 feet through this evening, highest in southern San Diego County. Surf will diminish early Thursday morning.

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



SGX WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...None.