...STRONG STRAIGHT- LINE WINDS...LARGE HAIL... AND LIGHTNING ARE MAJOR WEATHER THREATS IN THE NORTHWEST...

Thunderstorms may form by midday and carry on into the evening hours or possibly through the night. some threats from thunderstorms include large hail…lightning…and strong gusty winds.

Straight line winds

Downburst winds from a thunderstorm usually result when an area of air within the storm is cooled by raindrops, hailstones or by the evaporation of the raindrops. This pocket of cooled air, heavier than the surrounding air, accelerates downward to the ground. As the cool air impacts into the ground, it spreads out from the area of impact.

This process, in extreme cases, can cause winds higher than 100 mph. Weather forecasters call these bursts of wind "microbursts" if they are less than 2 1/2 miles across and "macrobursts" if they are greater than 2 1/2 miles across. These downbursts of air can be very hazardous and even life-threatening to people flying in airplanes and can cause extensive damage, injuries and fatalities at ground level as well.

Try to get indoors during all thunderstorm activity. High winds can suddenly develop, which can cause things on the ground to become swift moving airborne missiles, which can injure or kill.

Hail

Hail, another thunderstorm threat, often occurs in the northwest. Hail forms within thunderstorms as liquid water freezes in the cold mid and upper levels of the storms. The ice is kept aloft by strong updraft winds for a time, then when it becomes too large to be kept aloft by the updrafts, it cascades to the ground.

Hailstones may vary from pea-size to larger than softballs. Hailstones can do tremendous damage to farm crops, either as large hailstones or as a concentrated fall of small hailstones that accumulates to a depth of several inches. Large hail can easily damage vehicles and buildings and can be life-threatening to animals and people. Even small hail can be dangerous to motorists when it accumulates a few inches on roadways.

Lightning

One aspect of spring and summer storms is lightning. Each year about 400 people in the U.S. are struck by lightning while working outside or during other outdoor activities. In the United States an average of 62 people are killed by lightning each year and several hundred others are injuried and are left to cope with permanent disabilities.

Lightning often strikes as far as 10 miles away from any rainfall and has been documented to strike up to 70 miles away from the thunderstorm which generated the lightning. Many lightning victims are struck ahead of the storm or shortly after the storm has passed.

Outdoors is the most dangerous place to be during a thunderstorm. Watch for darkening cloud bases and head to safety before that first lightning flash. If you can hear thunder, the storm is close enough that it could strike your location at any moment, and you should seek shelter. If lightning is forecast, plan an alternate activity or know where you can take cover quickly.

If caught outside and lightning is in the immediate area,, and there are no safe locations nearby, the following steps will help decrease your chances of being struck by lightning. Do not seek shelter in partially enclosed building, or tall objects such as an isolated or small group of trees. Stay at least 15 feet apart from other members of your group so the lightning won't travel between you if hit. Keep your feet together and sit on the ground out in the open. If you can possibly run to a vehicle or building, do so! Sitting or crouching on the ground is not safe and should be used only as a last resort if an enclosed building or vehicle is not available.

Lightning injuries can lead to permanent disabilities or death. If someone is struck by lightning, call 9-1-1 or your local ambulance service. Give first aid as quickly as possible. People struck by lightning carry no electrical charge that can shock others, so you can examine them without risk.

Try to get indoors during all thunderstorms. When thunderstorms threaten you this season, tune to NOAA Weather Radio, The Weather Channel, or your local radio or television stations for up-to-date information.

This week is severe weather awareness week in the Pacific Northwest. Now is the time to get prepared for thunderstorms and hazardous weather such as strong gusty winds, hail, and lightning. Public safety information statements will be issued throughout the week to help you know how to respond when severe weather threatens.

This message is brought to you by your local NOAA National Weather Office.

HOW FAR IS THE LIGHTNING?
See the flash, then count 1000, 1001, 1002, 1003 and so on. Figure a count of 1000 to 1005 is one mile, as it takes thunder about 5 seconds to travel one mile. So, subtract 1000, then divide your count by 5. Now you know roughly how far away the lightning was.