Heavy rain, storm surge flooding are biggest risks in Florida from Tropical Storm Hermine
UPDATE: Aug. 31, 2016, 3:34 p.m. EDT Computer model projections have shifted significantly on Wednesday, now showing the risk for the storm to ride up the eastern seaboard over the holiday weekend. Coastal areas from North Carolina to Massachusetts may see heavy rain and strong winds from Tropical Storm Hermine, with impacts similar to a winter nor'easter, including coastal flooding concerns. Stay tuned to Mashable for further forecast updates on Wednesday night and beyond.
Tropical Storm Hermine, which formed on Wednesday, is forecast to strike the "Big Bend" area of Florida on Thursday night. It may not look all that fearsome right now, but it is still likely to have significant impact.
As of Wednesday at 2 p.m. EDT, the storm had maximum sustained winds of 40 miles per hour, after spinning for days as a tropical depression, which has weaker winds.
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Hermine is already bringing heavy rain to Florida, and could cause flooding from 6 to 12 inches of rain from Orlando northward to Jacksonville, given the weather system's slow movement and the abundance of moisture off the unusually warm waters of the Gulf of Mexico.
Because the storm is forecast to intensify, tropical storm warnings are in effect along with a hurricane watch between Tampa and Tallahassee, where the storm is expected to pass Thursday night into Friday morning (local Weather Service guidance can be found on this webpage).
The tropical storm warnings include Panama City and Panama City Beach, which are popular resort destinations.
The National Hurricane Center (NHC) has issued its first-ever prototype storm surge warning for a relatively sparsely populated area to the north of Tampa and south of Tallahassee.
A storm surge guidance map put out by the agency calls for 3 to 5 feet of storm surge from Ochlockonee River to the Suwannee River, with 2 to 4 feet of surge possible from Indian Pass to the Ochlockonee River.
Because of the shape of the coastline and the continental shelf offshore, Florida's Big Bend area is especially vulnerable to storm surge flooding. Such flooding comes on top of the normal tide levels and can result in total inundation, with levels high enough to damage coastal infrastructure.
This is the first year that the NHC is issuing prototype storm surge watches, warnings and maps, after research showed that hurricane warnings did not adequately convey the full extent of the storm surge threat.
In addition, research has demonstrated that the public has difficulty interpreting numerical storm surge guidance, with map-based products hopefully allowing people to better envision the threat they face, permitting wiser evacuation decisions.
If the storm strengthens into a hurricane, it would be the first to strike Florida since 2005 -- ending a record streak of years without such a storm there -- and it would elevate both the wind and storm surge threat.
However, with the storm still struggling to reach tropical storm intensity, that scenario is relatively unlikely, based on computer model projections and other weather data.
There is quite a bit of uncertainty regarding what happens to this storm after it crosses the northern part of Florida.
Some computer model projections take the storm close enough to the Carolinas for those areas to be impacted by rain and wind, and even show New England could face a threat from the system toward the end of Labor Day weekend.
Others turn the storm onto a more offshore track, which would spare other parts of the East Coast from this storm.
Andrew Freedman is Mashable's Senior Editor for Science and Special Projects. Prior to working at Mashable, Freedman was a Senior Science writer for Climate Central. He has also worked as a reporter for Congressional Quarterly and Greenwire/E&E Daily. His writing has also appeared in the Washington Post, online at The Weather Channel, and washingtonpost.com, where he wrote a weekly climate science column for the "Capital Weather Gang" blog. He has provided commentary on climate science and policy for Sky News, CBC Radio, NPR, Al Jazeera, Sirius XM Radio, PBS NewsHour, and other national and international outlets. He holds a Masters in Climate and Society from Columbia University, and a Masters in Law and Diplomacy from The Fletcher School at Tufts University.
