GOOD RAINS FORECAST FOR HILLS OF NORTH BAY. FIRE WEATHER WATCH SUNDAY NIGHT.

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As of 1PM Saturday, a band of moderate rain was visible on radar arriving in Mendocino County. (Image 1) Meanwhile satellite imagery shows the initial cold front progressing south. (Image 2)

Although it’s been drizzling for most of the day as the approaching front squeezes moisture from the marine layer, the real rain will arrive in Sonoma County in the mid to late afternoon. There has been remarkable agreement among the high resolution models as to the amounts, and distribution of rainfall.

All agree the coastal ranges will wring out the most moisture, with one half to even a full inch (in isolated spots) possible by early Sunday morning across the North Bay.

The wide views show forecast rain across Norcal….a nice soaking for many areas north of the Bay Area. (Images 3 and 4)

Closer in, we see the rain forecast to fall in the hills, with much less in the valley areas. However, given how dry the hills have been (above the marine layer), this is a welcome sign that areas with the most potential fire risk are getting wetting rains. (Images 5, 6, and 7) In all of these graphics, Sonoma County is at center.

Turning to late in the day Sunday, a Fire Weather Watch is in effect for areas of the North Bay above 1000 feet. (Image Moderate to strong offshore winds, with gusts to 50mph at the highest peaks, are expected to develop by 11PM Sunday as the frontal system passes to our east. This is a typical autumn wind event.

Less typical is the rain that will fall just before the winds arrive. This is the wild card that may moderate the fire danger. The NWS will decide on Sunday whether to upgrade the Watch to a Red Flag Warning based largely upon how much rain falls, and where.

On Monday, temperatures will rebound and winds from the northeast (breezes at lower elevations) will bring lower humidity and dry things out . The rest of the week looks dry and quite warm.