Why the Water Retreated From Florida Bays Before Irma's Storm Surge Arrived

Strong northeasterly winds ahead of Hurricane Irma pushed water out of Florida's waterways on the Gulf Coast from the Keys to Tampa Bay on Sunday.

(FULL COVERAGE OF IRMA: Hurricane Central)

Winds swirl in a counterclockwise motion around Irma's low-pressure center. This resulted in a northeast wind direction across Florida's Gulf Coast on Sunday morning.

Since the winds were strong and persistent from the same general northeast direction, the water had nowhere to go but away from the coast, exposing the underlying sand bed for an unusually long distance.

You can visualize this by thinking about how a small amount of water would move to one side of a bowl if you were blowing on it.

The retreating water led to tide levels that were over 3 feet lower than normal for that time of day in Naples and in Fort Myers at the Caloosahatchee River.

Images posted to social media showed exposed the mucky seabed of Tampa Bay and residents walking through puddles of sludge near the Bayshore Boulevard seawall.

The scene is just temporary, however. Once the center of Irma moves north of these areas, the winds will reverse direction and be out of the west or southwest. That will quickly funnel the water back toward the coast and send water levels surging.

(INTERACTIVE: How Much Storm Surge May Occur)

Storm surge is forecast to be as high as 10 to 15 feet above normal tide levels from Cape Sable to Captiva in southwest Florida, with life-threatening inundation expected all along Florida's western Gulf coast.

Tampa Mayor Bob Buckhorn warned residents of what was to come.

"We are about to get punched in the face by this storm. We need to be prepared," Buckhorn said. 

Storm surge was estimated at 10 feet above normal tide levels at Cudjoe Key, Florida, where Irma made landfall Sunday morning.

Brian Donegan is a meteorologist at weather.com. Follow him on Facebook and Twitter.