Fact or Faux: Can we get severe weather at night?

Weather Blog

ROCHESTER, N.Y. (WROC) — Hearing thunderstorms at night can be soothing to some, and a nuisance for others. But it’s important to know when storms do strike, they still can have the potential to be severe even during the night.

When we turn off the lights and the sun goes down, it’s important to not let our guard down completely, because contrary to what you may think it’s not impossible to see severe weather at night. It’s even a lot more common than you may think. So the answer to the question above is…

FACT

The general idea that goes is that when storms lose their prime fuel source, A.K.A. the sun, they lose the energy they need to form and/or strengthen. Many times this is in fact the case, but despite losing a prime fuel source, it’s not impossible under certain circumstances that storms can maintain their intensity and even strengthen well into the overnight hours.

This becomes essentially important to be aware of, especially when we’re talking about damaging winds, large hail, cloud to ground lightning and tornadoes. Tornadoes for example that occur at night are especially dangerous not only because it’s dark, but because they can be rain wrapped and hidden behind dark clouds too.

How does it happen?

Remember, all you need are these prime ingredients to get a severe thunderstorm: 

Shear, Lift, Instability, and Moisture

The instability is the key part here. When you have cold air directly above warm air, the warmer air will have the tendency to rise above the cooler air, because it’s naturally less dense.

Thunderstorms are generally fueled by the sun during the heating of the day when the air becomes warmer at the surface than the cooler air above it. This helps provide an unstable atmosphere and enough rising motion for storms. This is the first way, and most common way you get this kind of instability, or fuel for storms.

The difference between overnight storms is that at night, rather than warming the surface from “below” you’re cooling the air from above. You’re still getting the same instability, but the source has changed.

Thunderstorms that form at night can get their instability when enough cooler air moves in from aloft from a strong, incoming front. Surface convection can still form as a result from this especially after the ground is still warm from any residual heating from the sun during the day.

It can be trickier to predict storms like this since we lack measurements of both moisture and temperatures above the surface, which then becomes challenging for the meteorologist when situations like this arise.

Where does this happen?

Technically, any location that is capable of severe weather is fair game for nocturnal strong storms. There is a hot spot for this type of thing though, and it’s located a little farther south of here. Nocturnal thunderstorms happen most often across the Great Plains. The reason being is that they have a unique set up right next to the Rocky Mountains that can serve as an extra boost to storms. We call this extra boost the Low Level Jet, or Nocturnal Low Level Jet.

This jet sets up as warmth and moisture from the Gulf of Mexico is pumped in at the surface during the day. Over to the west, the air over the Rockies will cool down quicker at night, and when this cooler air is transported from west to east across this warmer, moist air below it serves as a bonus fuel source for storms. This is what helps them survive even past when the sun goes down.

Remember the Labor Day Derecho? That storm occurred overnight and brought widespread wind damage to many parts of the state including Western New York.

Oftentimes you can get a complex of storms like this with enough energy behind it to produce significant damage at a time when you least expect it.

Always check in with your local News 8 Meteorologists to get a sense of when you should be concerned for overnight strong storms.

Overnight Storm Safety

Most people are either sleeping at night, or they don’t have their TV’s and phones nearby to get the latest warnings. It’s always most helpful in situations like this to have a cell phone nearby with the volume on, or a NOAA Weather Radio if you don’t prefer having your phone on during the night. This would ensure you’d have the most warning possible in cases when severe weathers strikes. They can be just as dangerous if not more when taking into account the time of day when we’re not as aware of the weather happening around us.

Overnight Storms This Weekend

NOTE: Overnight downpours and perhaps a few storms will be likely as a frontal boundary makes its way across the region late Saturday night into Sunday, but we are not expecting a risk for severe weather that is worth losing any sleep over at this time.

There may be enough rumbles in any embedded stronger storms to wake you up during the night, and we may have to keep our eye on a few of these gusty downpours here and there, but this is not an instance we’re overly concerned about.

You can check up with the latest weather information with your local forecast HERE.

~Meteorologist Christine Gregory

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