San Diego, California

Isolated light showers will continue for the coastal basin this morning. More widespread moderate showers develop late this evening into Sunday morning, becoming more scattered during the day Sunday before tapering off Sunday afternoon and evening. Dry and warmer for the remainder of the week with highs near to a few degrees below normal each day.

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

UPDATED AVIATION/MARINE/BEACHES DISCUSSION

Morning water vapor imagery shows an upper level low near the Pacific NW coast with a trough extending south well off the coast of central Baja. The base of this trough is tapping some tropical moisture with PW in excess of 2" currently observed on satellite. The bulk of this moisture is forecast to remain to our south, but a weak and brief Atmospheric River is poised to move into far Southern CA this evening into Sunday morning. Ensemble mean IVT from the GEFS and EPS are on the order of 300-400 kg/m/s across San Diego County, and closer to 250 kg/m/s further north. A few light showers are possible this morning ahead of the trough, but the bulk of the precipitation from this system is expected to occur late this evening into Sunday morning. The majority of the high-res guidance is holding off on the heavier/more widespread precipitation until after 8 PM, so most will likely luck out on dry candy collecting conditions this evening. For the most part rainfall rates will be around a third-inch per hour or less, with isolated rates of half-inch per hour or more mainly in San Diego County. Showers will become more scattered and lighter by mid-morning Sunday, then tapering off from north to south Sunday afternoon, ending by Sunday evening.

Current rainfall forecast is for around 0.35-0.70" for the coastal areas and valleys, 0.50-1" in the mountains, and around 0.10-0.30" in the deserts, with the highest accumulations in San Diego County. Snow levels will be over 10,000 ft during the heaviest precipitation, falling to around 9,000 ft as precipitation tapers off this evening, leaving only trace amounts on the highest peaks of the San Bernardino and San Jacinto Mountains.

Transitory ridging and weak offshore flow builds in for Monday and Tuesday for relatively warmer weather, though highs will be a few degrees below normal inland - generally low to mid 70s for the coasts and valleys, low 50s to low 60s in the mountains, upper 60s in the high desert, and mid 70s to low 80s in the low desert. Another trough is forecast to move inland across the West Coast towards the middle of the week, though there is a lot of spread in the ensembles on the timing of this trough. For now forecast remains dry with this system with just some minor cooling. Weak troughing remains in place through Friday with little change in high temperatures each day.

311730...Multiple cloud layers across the coastal basin today with mid to high clouds in the deserts. Widespread precip moves into the coastal basin after 03Z Sun, bringing vis reductions (3-5SM) as well as cig reductions (2000-3000 ft MSL) under heavier rain. The highest confidence in heavier rain leading to the aforementioned restrictions is in San Diego County. -SHRA possible in the desrts 10-16Z Sun. Low to moderate confidence on timing of heavier rain occurrence in TAFs. Showers will become scattered after 18Z.

Westerly winds increase for Sunday afternoon and evening with gusts 20-25 kt. There is a 5% chance of isolated thunderstorms Sunday morning. Weaker winds expected Monday, followed by more elevated onshore winds Tuesday afternoon and evening, with gusts in the outer coastal waters potentially exceeding 20 knots.

An increasing southwesterly swell (3 ft at 15 seconds from 200 degrees) will bring elevated surf this weekend into Monday, with breaking wave heights 3 to 6 feet Sunday/Monday. While high tides will continue to wane through the weekend, tides will remain just above 6 feet which could still lead to local minor tidal overflow during high tides where breaking waves approach 5-6 feet, mostly on southwest facing beaches Sun/Mon.

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