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Rain returns tonight and some moderate to heavy potential exists

Posted at 2:53 PM, Dec 03, 2019

A storm system is expected to bring moderate to locally heavy rain to the region later this evening through mid-day Wednesday. There is a chance of thunderstorms Wednesday. Temperatures will be below normal the rest of the week. Another low pressure center will drop out of the Pacific Northwest this weekend will bring a chance of rain showers this weekend.

A weak atmospheric river will bring periods of moderate to heavy rain to the area, but the heaviest activity looks to take place from the Southcoast into Southern CA. Peak rain expected later tonight through early afternoon Wednesday, though light rain possible as early as this evening. Models have been struggling with the placement of the heavier rain bands. There is some instability with this system, especially when the upper low moves overhead Wednesday morning. There`s a slight chance of scattered thunderstorms and lightning.

No flash flood watch....yet. While rain rates are expected to be heavy at times, outside of thunderstorms peak rates are expected to be around a half inch per hour which is below critical thresholds. In thunderstorms those rates could rise to .75"/hr or locally higher, but chances of those falling over a recent burn scar are too low to go with a watch at this time, though not zero. Again the period of time when those higher rates is expected to be between 4am and 2pm.

Overall rain totals still look on track, .5-1.5" with locally higher (and lower) amounts.

Rain is expected to taper off Wednesday evening with mostly dry conditions Thursday but some scattered light rain is showing up on models.

Another tricky system coming in Fri some atmospheric river components to it but this one looks much weaker with the upper low remaining well north of our area. Some light rain possible northern areas Friday but otherwise dry.

Lots of uncertainty over the weekend on timing but it does look likely that most areas will see at least some rain before the weekend is out with the best chances Sat into Sat night. This is a much weaker storm with the upper low well to the north and no thunderstorms expected. There is a decent moisture so we could see another .5-1" of rain (especially along the northern SLO county coast).

We could see some lingering showers early Sunday but we are trending to a dry Monday and Tuesday.