While spring is by far the most active time of the year for severe weather and tornadoes, there is a second severe weather season that develops in the fall.
Most often, this second severe weather season spans late October into early November, affecting the South Central and southeastern U.S. However, severe events can also periodically affect areas farther north as well.
The driver for this second season is the jet stream, an area of strong winds high above the ground that divides cold air to its north from warm, moist air to its south.
The jet stream acts to support strong upward development of thunderstorms and also creates wind shear, a necessary ingredient for severe thunderstorm development.
Wind shear is a change in wind speed and/or direction with height above the ground. When winds change direction with height, they can cause thunderstorms to rotate and produce tornadoes.
In the fall, the jet stream starts to become stronger as temperature differences across the United States become greater. This happens as cold air from Canada starts to spread southward into the northern tier of the U.S. and clashes with warm, relatively humid air still in place across the southern tier.
The result is the development of severe thunderstorm and tornado outbreaks.
The right ingredients for a severe weather outbreak, including the risk of tornadoes, are expected to come together over the southern U.S. next week. AccuWeather.com Expert Senior Meteorologist Alex Sosnowski has the details on this potential.
The coldest air of the season so far has descended on northeastern Pennsylvania and the I-80/I-81 corridors. A storm will move in Saturday and tap into some of that cold air.
Looking for a unique holiday gift idea? Ice wine will provide a special, sweet flavor if the winter weather conditions are right.
The coldest air of the season so far has descended on central Pennsylvania. A new storm will move in Saturday and tap into some of that cold air.
Episodes of snow and slippery travel are forecast prior to the departure of Arctic air this weekend around Cleveland.
With more snow in the forecast, we'll take a look at how to stay warm at outdoor winter events and the conditions it takes to create the intricate designs in snowflakes.
The coldest air of the season so far is settling in around Boston. A new winter storm will move in this weekend and tap into the cold air.
First of three large snowstorms that winter. Over a foot of snow from mid-Atlantic states into New England: Nantucket Island 15.7" Philadelphia, PA 14.6" Baltimore, MD 14.1" Avoca, PA 11.1" Newark, NJ 20.4" Central Park, NY 19.6" Boston, MA 18"
The West (1995)
Monster storm slams into coast. Winds gusted to nearly 120 mph at Sea Lion Caves, OR. 80 mph winds at San Francisco, CA. 12.25" of rain fell in Marin, CA. 1.5 million people in the Bay area without power.
Second severe storm in 10 days hit settlers.