‘Unusually cold’ spring storm brings chances of lightning, hail Tuesday in Sonoma County

Following a week of temperatures reaching the high 80s, the North Bay is expected to cool down to below-normal temperatures this week as a cold front moves into the region, triggering widespread rain and chances for thunderstorms, lightning and hail, the National Weather Service said.

While it is normal to see some light rain in May, it is not typical to see daily high temperatures in the 50s and low 60s ― about 10 to 15 degrees below normal, said Roger Gass, a meteorologist with the weather service’s Monterey office.

“It’s definitely an unusually cold system to drop down into the region,” he said, in comparison with most springtime storms.

Lows will bottom out in the low 40s, about a degree or two cooler than average.

Light showers will begin Monday night across the North Bay and will cover most of the region by Tuesday. Rain will most likely diminish Wednesday, though there is a slight chance it will linger into Thursday and Friday, depending on where the low pressure system positions itself.

There’s a 20% chance of thunderstorms beginning about 11 a.m. Tuesday and through the evening. Lightning, hail and periods of heavy downpours ― up to about 1/10 of an inch per hour ― could occur during the storm, Gass said.

In total, up to 1/5 of an inch of rain is expected across the North Bay, with some coastal regions slated to received up to 1/2 of an inch.

Flooding will not be a concern during the storm, Gass said, though roads may be slippery and hail could pose a hazard on some roads.

“Mainly it will just be a travel hazard during the morning and evening commute,” Gass said.

You can reach Staff Writer Madison Smalstig at madison.smalstig@pressdemocrat.com. On Twitter @madi.smals.