How the new storm surge maps will work

Storm surge probabilities product (Courtesy: NOAA)
Storm surge probabilities product (Courtesy: NOAA)

MOBILE, Ala. (WALA) – Storm surge is a hurricane’s most destructive force. It’s also been one of the hardest things to accurately predict. The National Hurricane Center will be using new surge maps this year with a range of probabilities that give a range of what can expected.

Ivan's forecast 12hrs from landfall
Ivan’s forecast 12hrs from landfall (Courtesy: NOAA)

Hurricane Ivan makes a great example of how the new surge product can be helpful. The forecast path for Hurricane Ivan about 12 hours before landfall took the storm right through Dauphin Island and the center of Mobile County.

Surge forecast 12hrs from landfall
Surge forecast 12hrs from landfall (Courtesy: NOAA)

With that path, the storm surge models predicted a ten foot plus storm surge in Mobile Bay while in Pensacola Bay only around a two foot storm surge.

Ivan's Actual Path
Ivan’s Actual Path (Courtesy: NOAA)

Of course that’s not what happened. About twelve hour before landfall Ivan made a turn to the right and the actual path ended up about thirty miles to the east of the forecasted track.

Ivan's actual storm surge
Ivan’s actual storm surge (Courtesy: NOAA)

This made a huge difference with the storm’s surge. There was actually four to five feet of storm surge in Mobile Bay, while in Pensacola Bay there was eight plus feet of storm surge.

In order to get better numbers to emergency managers the National Hurricane Center put together a product with probabilities of storm surge.

Storm surge probabilities product
Storm surge probabilities product (Courtesy: NOAA)

This is what they would have seen twelve hours out. The probability was still high for Mobile Bay to get eight feet plus of storm surge at 50%, but Pensacola Bay’s probability wasn’t far behind with a 40 percent chance of an eight foot plus storm surge. The probability product gives emergency managers better numbers by averaging out several models and not putting all their eggs in one basket.

These probabilities are what we’ll see the next time a storm approaches the coast.

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