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THUNDERSTORM FAQs

Several places will have storm information. The local National Weather Service office in the area of the storm conducts damage surveys from severe weather events. The Storm Prediction Center documents storm reports, but the official designation is left up to the local National Weather Service Office. The NOAA National Climatic Data Center maintains the official national database for weather.

There is no one direction the wind comes from when thunderstorms or tornadoes occur. Where warm moist air is forced to rise by hills, mountains, or areas where warm/cold or wet/dry air bump together, thunderstorms can form. The surface direction of wind varies depending on your location (northern/southern hemisphere, and even coastal/plains/mountains), and what weather patterns usually affect the area.

One of our scientists has compiled statistics on severe weather hazards for the U.S. You can click on your area and a graph will come up showing what days of the year have the most thunderstorms. You might consider contacting your local National Weather Service Forecast Office because they will be more in tune with local climatology.

The answer to this question is that most things have a beginning and an end. The rain has to start somewhere and end somewhere. Sometimes it happens to start on one side of the street, and moves away, never getting the other side wet.

There is less convection on the west coast in part because of the cool water temperatures off shore in the Pacific Ocean. That impacts the temperature of air that moves inland, making it generally more stable and less convective; convection = thunderstorms). To get thunder you need strong updrafts (convection), which means rapidly falling temperatures with height (vertically) in the atmosphere.

Thunderstorm Climatology

Where are thunderstorms most common?

In the United States, thunderstorms are most common over the Florida Peninsula and the southeast plains of Colorado have the highest frequency of thunderstorms. Small thunderstorms occur about once a year in Alaska and 2-3 times a year in the Pacific Northwest.

Where are severe thunderstorms most common?

The greatest severe weather threat in the U.S. extends from Texas to southern Minnesota. But, no place in the United States is completely immune to the threats of severe weather.

When are thunderstorms most likely?

Thunderstorms are most likely to happen in the spring and summer months and during the afternoon and evening hours, but can occur year-round and at all hours.

• Along the Gulf Coast and across the southeastern and western states, most thunderstorms occur during the afternoon.

• Thunderstorms frequently occur in the late afternoon and at night in the Plains states

• Thunder and lightning can occasionally accompany snow or freezing rain!

HOW DOES NSSL CONTRIBUTE?

An NSSL scientist developed the Severe Thunderstorm Climatology to determine the probability of occurrance of severe weather events such as tornadoes, hail and thunderstorm winds.

In a project to estimate the likelihood of severe weather hazards in the U.S., an NSSL scientist compiled severe weather statistics for the entire country. (Severe thunderstorms are defined in the U.S. as having either torndoes, gusts at least 58 mph, or hail at least ¾ inch in diameter.)

There are three primary kinds of information available:

The average number of days per year with the event occurring within 25 miles of any point.
Animated loops of the probability of severe weather occurring within 25 miles of any point on a particular day with images once per week through the year.
Graphs showing the annual cycle of the probability of severe weather occurring within 25 miles at any point you select.

Go to: http://www.nssl.noaa.gov/hazard/hazardmap.html.