Gone are the days of temperatures in the 90s as the southern U.S. finally joins the rest of the country in the damp, dreary experience that is the arrival of fall. A ribbon of moisture direct from the tropical Pacific Ocean will team up with an approaching low to dump loads of heavy, much-needed rain on the south in the coming days.

Lots of Rain

The Weather Prediction Center—the branch of the National Weather Service responsible for issuing countrywide precipitation forecasts, among other things—expects a slug of heavy rain across just about every square inch of the Deep South between today and next week. They’re predicting the heaviest rain to fall in northern Texas around the Dallas-Fort Worth area, with a secondary bullseye down along the coast near Corpus Christi.

Precipitation forecasts like the one above are generalizations—actual rainfall totals can vary wildly from spot to spot and are completely dependent on the track of individual batches of rain and thunderstorms. Some areas could see much less than what’s forecast above, and some areas caught under a persistent line of storms could see much more than what’s forecast.

Steady rain is already falling across parts of New Mexico and western Texas at this hour. The heaviest rain will approach areas like Oklahoma City, Dallas, and Austin on Thursday, lasting on and off through the weekend in most spots. Severe weather shouldn’t be too much of an issue, but stronger storms could get just strong enough that they produce some damaging wind gusts.

Why It’s Happening

An upper-level low over the desert—the same one that’s triggered the heavy rain and severe thunderstorms in Arizona and New Mexico for the past couple of days—is running smack against a stream of tropical moisture hiking north direct from the extremely active Pacific Ocean. As the disturbance moves east and winds shift and bring more mugginess into the area, large-scale lift will trigger widespread batches of rain and thunderstorms.

The atmospheric moisture will only get thicker over the next few days, with precipitable water (PWAT) values exceeding 50 millimeters (about 2.00 inches) across Texas on Friday afternoon. Precipitable water shows you the amount of rain that would fall at a certain location if you were to wring out all of the moisture in the atmosphere above it. Higher PWAT values indicate a deeper reserve of moisture for thunderstorms to tap into and dump heavy rain.

What Does This Mean For You?

The biggest impact you’ll see is that vegetation (that isn’t dead yet) will look a little healthier and bodies of water will look a little more lively by the end of the weekend. After the flooding rains of last spring, much of the south has slipped back into drought, with a few spots already back into an “exceptional drought,” which is the highest level on the five-category scale.

Of course, this is also a double-edged sword. Heavy rain falling over parched ground is a recipe for flooding, and it’ll be a real threat during and after the heavy rain event. If you live in an area that commonly floods during bad rainstorms, be prepared to seek higher ground or alter your driving routes as necessary.

Pay close attention to your surroundings this weekend, especially if you’re visiting areas that are expecting heavy rain. Lots of people will be in Austin this weekend for Formula One, which is right in the middle of the area expecting several inches in the gauges by next week. If you’re going to be at any outdoor event (that isn’t outright cancelled) during the storms, make sure you have safe shelter in case there’s lightning nearby, and know more than one way to escape if you encounter rising water.

Never drive through a flooded roadway. The number one cause of death during a flood is someone driving through a flooded roadway; in other words, flooding is pretty much the only natural disaster where the majority of deaths are completely preventable and almost wholly attributed to human stupidity.

It only takes about a foot of swiftly-moving water to endanger even a large vehicle, and there’s no guarantee you’ll be rescued before you drown or suffer fatal trauma. Driving through a flooded roadway risks your life and the lives of those who have to rescue you or recover your dead body. Don’t do it.

[Maps: Author | Model Images: Tropical Tidbits | Satellite: NASA | Map at the top of this post updated at 4:53 PM EDT to reflect the latest WPC forecast.]

Email: dennis.mersereau@gawker.com | Twitter: @wxdam

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