Published: July 25, 2015
(MORE: Expert Analysis | Hurricane Central)
But even if there is no tropical development, a threat of flash flooding is underway for parts of the Florida peninsula.
(MORE: Florida Flooding Photos and News)
Let's break down what we know now, starting with the flood threat.
Setup For Potential Tropical Development
Setup For Potential Tropical Development
The Setup
A frontal boundary will stall out Saturday 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 could eventually develop into at least a tropical depression by next week.
On Friday evening, the National Hurricane Center said there was 20 percent chance that a tropical or subtropical cyclone could form in an area from near the Southeast Atlantic coast to near Bermuda during the next five days. The NHC lowered those odds to 10 percent late Saturday morning, noting conditions are "only marginally conducive" to any development.
Rainfall Forecast
Current Flood Alerts, Radar
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 and Flood Threat
While at least isolated thunderstorms are almost a daily occurrence in mid-summer in Florida, there is a swath of the state that may see repeated clusters of storms with heavy rain through much of next week.Some flooding is likely where rainfall persists the longest. Flash flood watches are in effect for a part of the west-central Florida coast, including the Tampa Bay area. About eight inches of rain fell near Holiday, Florida, in the 12 hours ending 8 p.m. EDT Friday, resulting in some reports of flooding.
- 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 some breaks in the rain.
However, keep in mind your outdoor plans may be interrupted multiple times during the day into the week ahead.
Incidentally, parts of Florida need the rain.
The most serious drought in the mainland U.S. is in south Florida, with "extreme" drought in parts of Miami-Dade and Palm Beach Counties, according to the latest Drought Monitor analysis.
Miami International Airport is running a 2015 rainfall deficit of over 12 inches. Several groundwater wells in Palm Beach and Miami-Dade Counties have plunged to the lowest 10 percent of levels on record, according to the U.S. Geological Survey.
As mentioned above, while parts of drought-stricken southeast Florida will see some rain, the heaviest rain will generally target areas of the Sunshine State not in drought.
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.
It's Happened Already This Season
Again, we think the chance of a tropical depression or storm forming in the eastern Gulf of Mexico or off the Southeast coast is low, but not zero.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.
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