Tropical Storm Cindy Could Cause Major Flooding Across the Southeast This Week

A water vapor image of Tropical Storm Cindy on June 20, 2017. Darker green indicates higher moisture in the atmosphere.
A water vapor image of Tropical Storm Cindy on June 20, 2017. Darker green indicates higher moisture in the atmosphere.

The stewing heat and humidity of a young summer finally gave way to the first tropical cyclone to threaten the United States this year. Tropical Storm Cindy is gathering steam in the Gulf of Mexico this week, and it promises to bring heavy rains to just about everyone in the southeastern United States. It won’t be a strong storm when it makes landfall, but wind isn’t as much of a concern as the copious amounts of tropical moisture being dragged northward, culminating in lots of precipitation and the potential for flooding.

As of Wednesday, June 21, 2017, tropical storm warnings are in effect for parts of the Gulf Coast from areas west of Houston, Texas, to as far east as Pensacola, Florida. Tropical Storm Cindy had winds up to 60 mph at 8:00 a.m. EDT Wednesday morning, and forecasters expect the storm to maintain winds of around 50 mph as it nears landfall. Winds of 45 mph are what you'd see in a healthy thunderstorm, but constant blustery winds over wet soil will make it easier for trees and power lines to topple over.

The traditional hurricane forecasting map—showing the forecast track of the center of the storm with a cone of uncertainty sweeping along its expected path—doesn't do much good in this situation. Sure, some areas will see gusty winds and power outages, but the real story with Tropical Storm Cindy is its rain. Cindy is a lopsided tropical storm with almost all of its heavy rain and wind shoved off to the east of the low-pressure center by wind shear higher up in the atmosphere. That's common to see in a weak, early season storm like this. Cindy's heavy rain will extend far beyond the center of the storm due to its lopsidedness and large size, so the forecast tracks we're all used to seeing don't go far enough to cover the threat posed by this storm. (If you'd like to see for yourself, forecasts are always available on the National Hurricane Center's website.)

Rain forecasts for Tropical Storm Cindy
The Weather Prediction Center’s rainfall forecast from June 20, 2017, through June 27, 2017
Dennis Mersereau

Tropical Storm Cindy will produce rainfall totals in the double digits in some locations through the end of the week, and the moisture from its remnants will continue to track inland through the weekend. The Tuesday morning precipitation forecast from NOAA’s Weather Prediction Center called for a widespread area across the Southeast to see more than three inches of rain by the time the storm finally clears out of the picture at the end of the week. Moisture from a landfalling tropical system is usually bad enough, but this storm will run into a pesky stationary front draped across inland areas of the Southeast. This front will help wring out the moisture and make it rain harder and longer than it would have otherwise.

This much rain over a short period of time will lead to widespread flooding concerns. If you live in or are visiting affected areas, make sure you know more than one route to get to where you're going. More than half of all deaths in a tropical storm or hurricane are caused by drowning. It's impossible to tell how deep the water is on a road before you drive across it, and it takes a surprisingly small amount of moving water to lift a car and sweep it downstream.

Denver is About to Experience Summer and Winter Temperatures Within 24 Hours

iStock.com/mphotoi
iStock.com/mphotoi

In a story tailor-made for exhaustive Weather Channel coverage, Denver, Colorado is about to experience one of the more bizarre weather shifts in recent memory. After an expected Tuesday high of 80°F, residents can anticipate a dramatic shift down to 32°F by midday Wednesday, with an initial half-inch of snow accumulation increasing to up to 7 inches by Wednesday night.

Put another way: Citizens who need to make sure they hydrate in the warm temperatures Tuesday will have to bring out the parkas the following day.

The Denver Post reports that the warm air coming ahead of the cold can result in a clash of air masses, prompting areas of low pressure that can create forceful and damaging weather conditions. The storm could bring winds of up to 60 miles per hour and possibly even cause power outages. Snow accumulation should dissipate by the weekend, when temperatures are expected to climb back into the 60s.

The high temperature record for April 9 in Denver is 81°F, set in 1977.

[h/t The Denver Post]

What Is a Bomb Cyclone?

Maddie Meyer/Getty Images
Maddie Meyer/Getty Images

The phrase bomb cyclone has re-entered the news this week as parts of the central U.S. face severe weather. Mountain and Midwestern states, including Colorado, Nebraska, Wyoming, and South Dakota, all fall in the path of a winter storm expected to deliver tornadoes, hail, heavy snow, flooding, and hurricane-force winds on Wednesday, March 13 into Thursday. It seems appropriate for a storm that strong to have bomb in its name, but the word actually refers to a meteorological phenomenon and not the cyclone's explosive intensity.

According to The Denver Post, the bomb in bomb cyclone stands for bombogenesis. Bombogenesis occurs when a non-tropical storm experiences at least a 24 millibar (the unit used to measure barometric pressure) drop within 24 hours. Low pressure makes for intense storms, so a bomb cyclone is a system that's built up a significant amount strength in a short length of time.

This type of storm usually depends on the ocean or another large body of water for its power. During the winter, the relatively warm air coming off the ocean and the cold air above land can collide to create a sharp drop in atmospheric pressure. Also known as a winter hurricane, this effect has produced some of the worst snowstorms to ever hit the U.S.

The fact that this latest bomb cyclone has formed nowhere near the coast makes it even more remarkable. Rather, a warm, subtropical air mass and a cold, Arctic air mass crossed paths, creating the perfect conditions for a rare bombogenesis over the Rockies and Great Plains states.

Central U.S. residents in the bomb cyclone's path have taken great precautions ahead of the storm. Over 1000 flights have been canceled for Wednesday and schools throughout Colorado have closed.

[h/t The Denver Post]

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