Published: July 26,2015
(MORE: Expert Analysis | Hurricane Central)
However, whether or not a tropical cyclone forms, the weather will remain unsettled for a while over parts of the Sunshine State.
(MORE: Florida Flooding Photos and News)
Let's break down what we know now, starting with the flood threat.
The Setup
Satellite and Surface Weather Map
A frontal boundary has stalled from near Bermuda southwestward to near the northwest Bahamas, across the Florida peninsula to the eastern Gulf of Mexico.
Boundaries such as this one 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.
A weak area of low pressure has formed in the upper levels of the atmosphere over the western Florida peninsula and adjacent waters of the eastern Gulf of Mexico. This upper-level spin is helping to 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.
As expected, a weak area of low pressure has also developed at sea level along that stationary front. As of Sunday evening, that low-pressure center was over the northeastern Gulf of Mexico just to the west of Tampa Bay.
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.
However, winds in the upper atmosphere are expected to remain hostile for development. The National Hurricane Center had been highlighting an area from the eastern Gulf of Mexico to off the Southeast coast for possible subtropical or tropical development during the next five days. They dropped that highlight early Sunday morning.
As of Sunday afternoon, NOAA's Cooperative Institute for Research in the Atmosphere (CIRA) still showed an area of potential development in that same zone – but the probability is no higher than 6 percent over the next 48 hours.
Rainfall Forecast
Current Flood Alerts, Radar
Impacts Regardless
Even though we are unlikely to see a tropical depression or storm form, 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 will see repeated clusters of storms with heavy rain into the new week ahead.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 10 inches of rain has fallen near Holiday, Florida, in the 48 hours ending 8 p.m. EDT Saturday, resulting in some reports of flooding. Tarpon Springs, Florida, has seen 8.56 inches of rain over the past three days, according to CoCoRaHS volunteer weather observations.
Flooding on the Anclote River from heavy rain the last several days resulted in an evacuation of some homes in Elfers (southwest Pasco County) on Sunday.
Here is a general look at the forecast to start the new week:
- Most numerous t-storms, flood threat: Central, southwest, possibly northeast Florida (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 nearly 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 may eventually produce elevated surf along parts of the Southeast coast, from Florida's First Coast to southeast Georgia and South 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.
Onshore winds are currently contributing to a high risk of rip currents along central and southern portions of the Florida Peninsula's west coast, bordering the Gulf of Mexico.
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
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 this 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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