A major flash flood event could unfold over the next couple of days as what is likely to become Tropical Storm Bill limps its way towards Texas. What the storm lacks in vivacity it will more than make up for in intense rainfall. The storm will produce flooding rains from Houston to New York City, causing major flash flooding in areas that already have more water than they can handle.

The system—which is officially called “Invest 91L” right now—is attempting to develop in the favorable atmosphere over the Gulf of Mexico at this hour, but a Hurricane Hunter aircraft that flew into the storm this morning did not find a closed area of low pressure at the surface. The storm is producing 45 MPH winds, however, so it is the strength of a tropical storm without actually being one. The effects are still the same whether or not it becomes Tropical Storm Bill.

There’s No Such Thing as “Just” a Tropical Storm

Texas is the one part of the country that doesn’t need to be told that even something that’s “just” a tropical storm is dangerous. We recently passed the 14th anniversary of Tropical Storm Allison, a system that made landfall in Texas and stalled over the state for a week, dropping more than three feet of rain in the region, causing catastrophic flooding that killed dozens of people and produced billions of dollars in damage.

That being said, the two storms are nothing alike. PossiBill won’t stall out, but rather it’s forecast to loop around the big ridge of high pressure that’s currently baking the southeastern United States in a record-breaking heat wave. This morning’s run of the models pretty much agree on the general track that the system will take (whether or not it fully develops), and it’s not looking too good for areas already inundated by rainfall over the past couple of months.

Track Is Everything

Above is a spaghetti model plot showing the potential track of the center of the storm according to various runs of the major weather models this afternoon. It’s clear that the system will make landfall somewhere between Corpus Christi and Galveston, moving through Texas before hooking northeast and eventually east around the dome of heat in the southeast. The ultimate track of the storm is key in who sees how much rain—the majority of the precipitation will likely be along and to the east of the storm’s track, so just about any of these potential tracks puts Houston in a bad spot for flooding.

Flooding

While any gusty winds are dangerous when the soil is this saturated (it won’t take much to down trees and power lines), the greatest threat with possiBill will be flash flooding. The big weather story over much of the past couple of months has been the incredible amount of rain that’s fallen over Texas and Oklahoma, with flash flooding in just about every major city from San Antonio to Oklahoma City.

The Weather Prediction Center expects that this system will add to those totals in earnest, with many areas (especially in eastern Texas) exceeding seven inches of rain under the heaviest showers and thunderstorms that spiral through the area. While the focus is on Texas due to the recent flooding, heavy rain is expected all along the path of possiBill’s remnants—a swath of five or more inches of rain is possible from Houston through cities like Joplin, St. Louis, Indianapolis, Columbus, and Pittsburgh. Again, exact totals will differ based on location and the ultimate track of the storm, but it’s a good idea of what to expect if you live in any of the areas affected by this system.

Flash flood watches are already in effect for much of Texas and parts of the Midwest and Great Lakes region, and these watches will likely fill in across possiBill’s predicted track as confidence increases in the likelihood of a high-impact, high-water event. The watches up near the Great Lakes are also in place for the daily regime of pop-up thunderstorms that’s plaguing the region thanks to the heat wave down south; the latest flash flood guidance shows that it’ll only take about one inch of rain falling in a three-hour window to trigger flash flooding across much of Ohio and western Pennsylvania.

How to Prepare Ahead of Time

If you live in a flood zone, you likely already know the drill. Make sure you have a plan in place in case you need to quickly head to higher ground, keeping in mind that one or more of your escape routes could be inaccessible. If you don’t live in a flood zone (or don’t know), don’t assume you’re completely safe from rising waters. Keep an eye on flash flood warnings issued by your local National Weather Service office and keep checking outside to make sure you’re not suddenly an island in the middle of a rising ocean.

Keep your cell phone charged, your gas tank at least half full, and make sure you can quickly access cash, important documents, and enough prescription medication to last you a couple of days if you need to evacuate in a hurry or if the power goes out. Cash is especially important in the latter instance—your cards are worthless pieces of plastic if the power goes out or the telephones go down.

Not many people can afford to put their lives on hold for some heavy rain, so just about everyone affected by the storm over the next couple of days will go about their day to the best of their ability. Be proactive about your own safety. If you know that one of the roads on your route to work or school or home has a tendency to flood, find alternate routes now so you don’t get stuck or, worse, trapped in floodwaters.

Last, but not least, do not drive through a flooded roadway. Assume you won’t make it. Even if you theoretically could make it, assume you won’t. It’s not worth the risk. It only takes a couple of inches of swiftly-moving water to sweep you off of your feet, and it doesn’t take much more to strand a vehicle or sweep it away. Even the largest, most testosterone-dripping pickup trucks can easily get caught in high water and put passengers in the same scenario as someone driving a Smart Car.

The majority of flood deaths in the United States occur when people drive into high water and drown before help can arrive. Not only do people risk their own lives by driving through a flooded roadway, but they risk the lives of the men and women who have to go into the flood to rescue them or recover their dead bodies.

Keep an eye on the National Hurricane Center (hurricanes.gov) and the National Weather Service (weather.gov) over the next couple of days to keep up with the latest forecasts and warnings associated with this system, whether or not it becomes a tropical storm. And, as always, keep checking with The Vane for more detailed weather analysis and information on this and any other disasters looming on the horizon.

[Maps: author | Satellite: NASA | Image of flooding on I-45 in Houston on May 26, 2015: AP]

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