Although spring has the best reputation for severe thunderstorms and damaging tornadoes, a whirlwind can swirl somewhere in the US in any month.
But the areas most vulnerable to tornadoes change throughout the year as the jet stream migrates north and south.
Using statistical analysis on the location and frequency of confirmed tornadoes in the US since 1950, Shane Brown, senior weather data specialist at FOX Weather, compiled the series of maps below that depict the areas most prone to twisters each month.
During the winter months, when most of the country is shivering in cold temperatures, you will find that there is still a good probability of tornadoes in the South.
This is because the jet stream sets up camp in the southern US for the winter, causing a significant temperature difference between cold air to the north – which originates in Canada – and warm air to the south drawn in from the Gulf of Mexico.
During the winter, there is still a good chance of tornadoes in the South, according to Fox Weather. Fox weather
The jet stream is also strongest 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 thunderstorms to develop and intensify, possibly leading to the formation of tornadoes.
Severe winter storms are often found where there is a southward jet stream – called a trough – or a cold front moving through the area.
Southern states have seen tornadoes during cold weather, such as Fort Lauderdale, Florida (seen above) on January 6, 2024. FOX Weather
By spring, the jet stream remains relatively strong as it begins its northward migration.
This causes the tornado threat to also spread further north as we progress through March, April and May.
Temperatures in the 80s and 90s could penetrate north into much of the Plains and Midwest, including “Tornado Alley,” by April.
The warmth is often accompanied by dew points in the 60s or 70s, indicating a moist air mass that can provide fuel for severe thunderstorms and tornadoes.
May is the most active month in history for tornadoes, with an average of 294 spins each year.
That was followed by April and June, each with an average of 212 tornadoes.
In the summer, the jet stream is usually positioned near the US-Canada border, which causes tornado threats to increase for the northern and central Plains and Midwest in July and August.
Summer is also the best time of year for the meandering of the Northeast and mid-Atlantic states.
May is the most active month in history for tornadoes, with an average of 294 spins each year. Fox weather
Given the amount of heat and humidity available, tornadoes can form almost anywhere during the hottest months.
Secondary peaks in tornadoes often occur in the fall, especially in the Gulf Coast region.
This is because the jet stream begins to retreat to the south and strengthens as the atmosphere transitions from summer to winter.
In the summer, tornado threats increase in the northern and central Plains and Midwest in July and August. Getty Images/iStockphoto
However, severe weather from fall to early winter can sometimes penetrate north into the Ohio Valley and southern Great Lakes, as we saw in December 2021 when a large EF-4 tornado tore a nearly 166-mile path of destruction across western Kentucky.
Climatologically, by November and December, the threat of major tornadoes is limited to the South, where temperatures and humidity generally remain higher due to the influence of the Gulf of Mexico.
Any late-season tropical activity can also increase severe weather along the Gulf Coast in November and December.
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Source: thtrangdai.edu.vn/en/
