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Thunderstorms Expected To Rumble San Diego

Thunder rumblings are expected in the mountain and deserts areas of San Diego County today as summer thunderstorms threaten the region.

Rare thunder and lightning are expected to roll through San Diego County today. The summer storm could rumble neighborhoods and light up the skies -- from the mountains to the coast.

Lightning Safety Tips

PLAN in advance your evacuation and safety measures. When you first see lightning or hear thunder, activate your emergency plan. Now is the time to go to a building or a vehicle.

IF OUTDOORS...Avoid water. Avoid the high ground. Avoid open spaces. Avoid all metal objects including electric wires, fences, machinery, motors, power tools, etc. Unsafe places include underneath canopies, small picnic or rain shelters, or near trees. Where possible, find shelter in a substantial building or in a fully enclosed metal vehicle such as a car, truck or a van with the windows completely shut. If lightning is striking nearby when you are outside, you should:

A. Crouch down. Put feet together. Place hands over ears to minimize hearing damage from thunder.

B. Avoid proximity (minimum of 15 ft.) to other people.

IF INDOORS... Avoid water. Stay away from doors and windows.

INJURED PERSONS do not carry an electrical charge and can be handled safely. Apply First Aid procedures to a lightning victim if you are qualified to do so. Call 911 or send for help immediately.

Source: National Lightning Safety Institute

The rare storms occur when moisture and unstable air masses come together. The National Weather Service is warning the subtropical moisture moving in from the east will likely pack a punch.

"This weather system is pretty massive," said Robert Ballfour, senior forecaster with the National Weather Service. "It’s got a lot of moisture with it, and all the parameters that we look at point to the possibility of flash flooding, especially over the mountains and the desert areas. This evening there’s a good chance it’s going to move west of the mountains and come across the valleys and even reach the coast."

Balfour said lightning activity is forecast as a category 4, which means about 15 or more strikes every five minutes. He added that the threat of fires from lightning strikes has diminished.

"The moisture column or the whole air mass has moistened up considerably," Balfour said. "Just a measure of the surface moisture which usually is going to control the spread of a fire—you want to see that below 45 percent because otherwise the grass just won’t carry the fire, and right now it’s 65 percent and climbing to about 80 percent, and then we do expect wetting rains."

A flash flood watch for local mountain and desert areas is scheduled from 11 a.m. through this evening.

"A slow cooling trend will develop for Friday through the weekend, as a weak trough of low pressure develops near the west coast,'' according a weather service advisory.

City News Service contributed to the information in this report.

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