Good news! We’re pretty sure that Hurricane Joaquin is going to head out to sea, with the chance of landfall on the United States fairly low at this point. The bad news is that there will still be more than a foot of rain in parts of the Carolinas, and stiff onshore winds and high waves will create coastal flooding in the Mid-Atlantic much like a storm surge would.

Flooding Rain

The big weather story at the moment (in the U.S., at least) isn’t Hurricane Joaquin, but rather the potential for significant—possibly devastating—flooding along parts of the East Coast today through early Monday.

The Weather Prediction Center is calling for more than ten inches of rain in South Carolina, with quite a few spots probably seeing more than a foot of rain by the time the skies clear out next week. The National Weather Service office in Charleston keeps calling this a “historic” rainfall event, pointing out that life-threatening flash flooding is likely across areas expected to see the heaviest precipitation.

Rainfall totals gradually fall off once you leave the Palmetto State, but given recent rains—a nearby weather station says we had a foot of rain in four days earlier this week at The Vane’s glass-enclosed nerve center in central North Carolina—it won’t take much heavy rain to trigger flash flooding elsewhere.

As such, flash flood watches are in effect for...well, everyone who lives between the Atlanta and Baltimore metro areas, including eastern Georgia, the entire states of North and South Carolina, all of Virginia save for three mountain counties, the entire D.C. area, and parts of West Virginia and the Delmarva Peninsula.

We’re seeing Rainpocalypse II only in part because of Joaquin. An upper-level low embedded in a sharp trough in the jet stream, along with a developing low at the surface, will work together to wring the tropical moisture out of the atmosphere and into backyards and basements across the southeast. While it’s not the storm itself, Joaquin certainly isn’t helping matters—a good chunk of the tropical moisture over the East Coast this weekend will come direct from the hurricane itself.

Hurricane Joaquin

Joaquin still has 130 MPH winds as it slowly—finally—starts making its way north as the trough over the southeast kicks it away from land. The National Hurricane Center’s latest forecast shows Joaquin slowly weakening over the next couple of days as it picks up speed and heads northeast out to sea. Bermuda will need to watch this storm closely—any eastward shift in its track could lead to a significant impact on the tiny island.

For the second day in a row, the worst winds and rain in Hurricane Joaquin are pounding the central Bahamas. Several sparsely populated (but populated nonetheless) islands have experienced the full effects of this category four hurricane for more than 24 hours.

In addition to the widespread flooding and wind damage that likely occurred on the affected islands, news reports indicate that a Puerto Rico-bound cargo ship with 33 people aboard stopped communicating during the height of the storm and may have been lost in the waters of the central Bahamas. A U.S. Coast Guard plane is flying into the hurricane to see if they can find the ship.

The above map shows the probability of tropical storm force winds according to the National Hurricane Center. The probabilities range from 10% (dark blue) to 100% (bright red), and no portion of the United States is under a serious threat from this storm at the moment.

However...

Wind

Many locations on the eastern seaboard are still experiencing tropical storm force winds, just not as a result of a landfalling system. We’re dealing with a powerful hurricane running smack against a strong ridge of high pressure over eastern Canada, which is creating an exceptionally tight pressure gradient in between that’s shooting wind ashore like a jet engine.

The result is a stiff, relentless onshore wind that’s creating a nightmare for communities along the coasts of New Jersey, Delaware, and Maryland. The strong winds are pushing a couple of feet of water ashore—just like the storm surge in a hurricane—and when you combine that wind-driven surge with high waves, high tide, and ongoing beach erosion, the situation gets worse with each passing hour and each time we experience high tide.

Though weakened, the gust winds will continue inland, where the combination of windy conditions and saturated ground will allow for trees and power lines to fall with ease. There are several thousand power outages right now across the Carolinas and Mid-Atlantic—nothing too bad, but it won’t take much wind to take down the wrong tree and plunge folks into darkness for a few hours. Also, falling trees do not tickle if they hit humans or pets, so be mindful of where you’re walking, driving, and what’s looming overhead at home.

Tornadoes

It’s worth mentioning that there’s a small risk for tornadoes right along the coasts of North and South Carolina over the next couple of days. Thunderstorms that come ashore and encounter low-level shear could begin rotating and spin-up a quick tornado or two. Brief tornadoes are very dangerous because they can occur with little or no warning. Stay alert and check the radar as often as possible.

Prepare

While you’re probably not going to see a full-fledged hurricane making landfall, there’s still going to be enough widespread nasty weather that anyone reading this from Florida to Maine should get ready for some sort of hazardous conditions, whether it’s flooding rains in the Carolinas, coastal flooding in the Mid-Atlantic, gusty winds bringing down trees, or just high waves and rip currents making it unsafe to go in the water for the next few days.

You have to be proactive about your own safety. Have a plan in case the power goes out; keep your cell phone charged, make sure you have gas in the car and a little bit of cash on hand, and ensure you have bottled water and some food to eat that doesn’t need to be cooked.

As I said yesterday, make a mental map of where you go during your daily routine, whether it’s your route to work, school, church, home, or wherever. Check with local sources to see if those roads are susceptible to flooding, and go to great lengths to avoid those roads during or just after heavy rain. Stay home if you can! It’s a great excuse to do nothing this weekend.

If you come across a flooded roadway, don’t drive across it. It sounds silly to say, but thousands of people attempt it every year, and it’s the number one cause of flood-related deaths in the United States. Every flood event, people misjudge the depth of the water, make a go at it, and they get stuck. If they’re lucky, they survive and rescue crews can get them. If not, they get swept to a brutal death or simply drown in the rising water.

It’s not worth driving across a flooded roadway, because not only does it risk your life, but it also risks the lives of those who have to go into the water to rescue you or recover your body. Just don’t do it.

[Satellite: NASA | Model Image: GREarth | Maps: author]

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

My new book, The Extreme Weather Survival Manual, comes out next Tuesday! You can pre-order it now from Amazon.