National Oceanic and Atmospheric Administration (NOAA)
As is often the case in July, the Atlantic tropics were quiet after Hurricane Beryl slammed into Texas and the short-lived Tropical Storm Chris moved into Mexico. But now that the African dust has cleared from the atmosphere and August is well underway, the oceans are waking up.
Tropical Storm Debbie formed this weekend, and forecasters at the National Hurricane Center say the system will likely reach Category 1 hurricane strength before making landfall on Florida’s west coast on Monday.
As far as hurricanes go, this isn’t the most threatening storm we’ve seen in the Sunshine State in years. Yes, no one likes hurricanes or the storm surge they bring. But Debbie is likely to hit a relatively sparsely populated part of Florida, and will likely unleash a lot of wrath on protected areas and wildlife areas. It’s never fun, but as a hurricane, it’s probably pretty manageable from a wind and surge standpoint.
Major flood storm expected
But a much bigger threat from Debbie is looming over the Southeastern United States next week: a major flood storm. Historic flooding is expected across Florida, Georgia and South Carolina.
Debbie is currently moving north-northwest at a fairly good 13 mph as of Sunday morning. This is a fairly common path for a hurricane to pass through the edge of a high-pressure system. Then, when the hurricane gains enough latitude (as Debbie is doing now), it turns polar and eventually moves northeast.
Debbie is expected to wander next week.
National Hurricane Center
And that’s exactly what Debbie could do on Monday. But after that time, the high pressure that’s forming over the mid-Atlantic is expected to be strong enough to block Debbie’s path to the northeast. If that happens, the storm will be blocked off the coast of Georgia and the Carolinas for two or three days.
There is still a lot of uncertainty about where Debbie will go after it hits Florida. It will most likely pass through Georgia on Tuesday, after which the center could re-emerge into the Atlantic. However, the center is likely to remain near or just off the coast. From there, it could advance into very warm waters, with temperatures ranging from 83 to 85 degrees Celsius.
In this pattern, with nearly stationary storms, the rain bands can be continually replenished with moisture drawn from the ocean. This produces intense tropical rainfall and “training”, where the rain bands remain more or less in a given area, fed by coastal moisture.
With the pattern still a few days away from forming, and the uncertainty surrounding Debbie’s path, it’s hard to say exactly where the heaviest rain will fall. But the National Weather Service’s Weather Prediction Center, the division tasked with forecasting precipitation, is predicting some pretty impressive totals for the period between now and Friday.
Weather bell
From Savannah, Georgia, north to Hilton Head Island and Charleston, South Carolina, the National Weather Service is expecting 20 to 25 inches of rain, with some areas expecting even higher amounts. Additionally, these high amounts could extend dozens of miles inland.
The African wave train begins operation.
Due to uncertainty about Debbie’s movement, parts of Florida and North Carolina could also see extremely heavy rainfall over the next few days.
And that’s not all. As August deepens, tropical waves have begun to blow off the west coast of Africa. One of these is now approaching the Windward Islands and will move into the Caribbean next week, where it has the potential to develop into a tropical storm or worse. This is likely the beginning of a period of intense activity that is characteristic of the Atlantic tropics during August, September, and the first half of October.
All of this is consistent with forecasters’ expectations that the Atlantic hurricane season will be a very busy one, as an unusually warm Atlantic (where climate change is causing the ocean to reach its warmest temperature on record) and an impending La Niña event in the Pacific Ocean create favorable conditions for hurricane development in the Atlantic basin, including the Caribbean and Gulf of Mexico.
