Tropical Development Possible as Dying Front Stalls off the Southeast Coast; Florida Heavy Rain Threat Ahead

Jon Erdman
Published: July 23,2015

The 2015 Atlantic hurricane season has already featured three rather short-lived named storms.
We now have our eyes on an area near the Southeast U.S. coast for potential development in the coming days.
(MORE: Expert Analysis | Hurricane Central)
Even if there is no tropical cyclone, one popular vacation destination is likely to get a soaking.
Let's break down what we know now.

Setup For Potential Tropical Development

 

 

 

 

 

 

 

 

The Setup

Meteorologists look for patterns in both upper-air and surface computer model forecasts when identifying potential weather scenarios in the extended range, say, beyond three days or so.
(MORE: What to Expect in July in the Tropics)
Heading into the final week of July, one such pattern, in particular, is drawing our interest.
A frontal boundary is expected to stall out from near Bermuda southwestward to near the northwest Bahamas, across the Florida peninsula to the eastern Gulf of Mexico.
These boundaries help focus clusters of showers and thunderstorms over the mainland in the spring, summer and fall, and the same can be true, at times, in the Gulf of Mexico as well as the subtropical Atlantic basin.
Computer guidance also suggests a weak area of low pressure in the upper levels of the atmosphere may form near the Florida peninsula or eastern Gulf of Mexico. This upper-level spin may help boost the formation of showers and thunderstorms and diminish upper-level shearing winds otherwise hostile for developing tropical cyclones.
The front's location over the warm Gulf stream and northeast Gulf of Mexico water only adds low-level warmth and moisture to the air, increasing instability, or the ability to generate convection.
One or more areas of low pressure may eventually form at sea level along that stationary front somewhere off the Southeast coast or in the eastern Gulf of Mexico.
If a cluster of showers and thundershowers can develop in the same place as a low-pressure center and persist, it may eventually develop into at least a tropical depression by next week.
If one does form, it would most likely get pushed northeast, remaining off the Southeast coast, but that is not a guarantee at this point.

Rainfall Forecast

Rip Current Threat

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Impacts Regardless

Whether or not a tropical depression or storm develops, there are two significant impacts that will result from this pattern.

Heavy Rain

While at least isolated thunderstorms are almost a daily occurrence in mid-summer in Florida, here is a general outlook of where the heavy rain threat is greatest, and who may see less thunderstorms:
- Most numerous t-storms, flood threat: Central, southwest, northeast Florida, possibly far southeast Georgia (FORECASTS: Orlando | Daytona Beach | Tampa/St. Pete)
- Less numerous t-storms: Florida panhandle, southeast Florida and the Florida Keys (FORECASTS: Pensacola | Miami | Key West)
Of course, this doesn't mean a complete washout is likely in the areas mentioned above for most numerous thunderstorms. There will be breaks in the rain.
However, keep in mind your outdoor plans may be interrupted multiple times during the day into the week ahead.

High Surf/Rip Currents

Northeast winds this weekend into at least early next week may eventually produce elevated surf along parts of the Southeast coast, from Florida's First Coast to southeast Georgia and the Outer Banks of North Carolina.
Accompanying this will be a threat of rip currents. Keep this in mind particularly if you're vacationing in these areas. Rip currents can and often do occur when the weather is otherwise tranquil. Heed all warnings from lifeguards.

2015 Atlantic hurricane season named storm tracks, as of July 21, 2015.

Origin locations of Atlantic Basin named storms from July 21-31, based on climatology since 1950. Note the number of tropical cyclones that have formed in late July in the Gulf of Mexico and southwest Atlantic Ocean, off the Southeast coast of the U.S.

It's Happened Already This Season

This is a relatively common early-season pattern known to generate tropical cyclones near the U.S. coast.
Despite high wind shear squashing any chance of tropical development in the Caribbean Sea, the Atlantic Basin has manufactured three named storms so far this season, all either close to, or landfalling in, the U.S.
On Mother's Day weekend, Tropical Storm Ana was the earliest East Coast landfall on record.
A little more than a month later, Tropical Storm Bill soaked an already saturated southern Plains, Ozarks and Ohio Valley.
Finally, a disturbance that originated from a Midwest thunderstorm cluster sprouted convection over the Gulf Stream and developed into Tropical Storm Claudette on July 13.
Last July, Hurricane Arthur formed in this same general area, off the southeast U.S. coast, pounding eastern North Carolina and southeast Virginia on the July 4th holiday weekend.
If you have vacation plans next week from the northern and eastern Gulf Coasts to Florida and the Southeast coast as far north as the Outer Banks of North Carolina and southeast Virginia, don't cancel them yet.
But, do check back with us at weather.com, Weather Underground, and The Weather Channel for the latest on this situation.

MORE: Tropical Storm Ana - May 2015