While spring has the most notorious reputation for severe thunderstorms and destructive tornadoes, a tornado can appear somewhere in the US during any month.
But the areas most vulnerable to tornadoes change throughout the year as the jet stream migrates from north to south.
Applying statistical analysis to the locations and frequencies of confirmed tornadoes in the U.S. since 1950, Shane Brown, senior weather data specialist at FOX Weather, compiled the series of maps below illustrating the areas most susceptible to tornadoes in each month.
During the winter months, when much of the country is shivering from low temperatures, you’ll notice that there is still a decent chance of tornadoes in parts of the south.
This is because the jet stream sets up camp in the southern United States during the winter, causing a marked temperature contrast between the cold air from the north (from Canada) and the warm air from the south from the Gulf of Mexico. .
During the winter months, there is still a decent chance for tornadoes in parts of the South, according to Fox Weather. Weather in Fox
The jet stream is also stronger in winter due to the collision of air masses.
A stronger jet stream can fuel severe weather, adding the necessary spin and energy in the atmosphere for storms to grow and intensify, possibly leading to the formation of tornadoes.
Severe winter storms are often found when there is a southward tilt in the jet stream (called a trough) or a cold front moving through a region.
Southern states have seen tornadoes during cold weather, such as Fort Lauderdale, Florida (seen above) on January 6, 2024. FOX Weather
In the spring, the jet stream is still quite strong as it begins its northward migration.
This causes the tornado threat to also extend further north as we move into March, April and May.
Temperatures in the 80s and 90s may penetrate northward across much of the Plains and Midwest, including Tornado Alley, in April.
The heat is often accompanied by dew points between 60 and 70 degrees, indicating a moist air mass that can provide fuel for severe thunderstorms and tornadoes.
May is historically the most active month for tornadoes, with an average of 294 tornadoes each year.
April and June follow, each with an average of 212 tornadoes.
In the summer, the jet stream typically parks near the United States-Canada border, causing the tornado threat to increase in parts of the northern and central Plains and the Midwest during July and August.
Summer is also the most favorable time of year for tornadoes in the Northeast and Mid-Atlantic states.
May is historically the most active month for tornadoes, with an average of 294 tornadoes each year. Weather in Fox
Given the amount of heat and humidity available, a tornado can form virtually anywhere during the warmer months.
A secondary peak of tornadoes usually occurs in the fall, especially in the Gulf Coast region.
This is because the jet stream begins to retreat southward and strengthen as the atmosphere transitions from summer to winter.
In the summer, the tornado threat will increase in parts of the northern and central Plains and the Midwest during July and August. Getty Images/iStockphoto
However, severe weather from fall through early winter can sometimes penetrate as far north as the Ohio Valley and southern Great Lakes, as we saw in December 2021, when a massive EF-4 tornado opened up a path of destruction nearly 166 miles long through western Kentucky.
Climatologically, in November and December, the main tornado threat is limited to the south, where temperatures and humidity typically remain higher due to the influence of the Gulf of Mexico.
Any late tropical activity may also increase severe weather along the Gulf Coast in November and December.
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Source: vtt.edu.vn