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'Hurricane' Schwartz: What if Joaquin hit?

Most computer models greatly underestimated the Joaquin rapid intensification from a tropical storm to a Category 4 with 130 mph winds.

MAJOR COASTAL FLOODING WITHOUT JOAQUIN

Below is the track of Hurricane Joaquin as shown by areas of tropical storm force (49 mph) and hurricane force (74 mph).

Joaquin clearly tracked well out to sea, with the hurricane-force winds never getting within 450 miles of the U.S. East Coast. Yet major coastal flooding occurred and wind gusts reached 60 mph that week. Obviously, it was not Joaquin itself that was the culprit.

Look at the map from Sept. 30. It's nice and colorful, but might be hard to read. It stretches from the Pacific Ocean on the left to Africa and Europe on the right. The lines and colors represent air pressure at the surface. Joaquin is the "bulls-eye" in the middle of the map. And the other important feature is the big pinkish blob in Eastern Canada. That's the huge blocking HIGH that we were talking about all week.

The closer the lines are together, the stronger the wind. Of course, they're closest around Joaquin, but there are also a lot of them between the storm and the big HIGH in Canada. This is the "pressure gradient" that we talk about sometimes. A blocked pattern like this led to day after day of strong onshore winds. Hence the flooding, high tide after high tide after high tide.

SOME RELIABLE MODELS DID PREDICT A DIRECT HIT HERE

Most computer models greatly underestimated the Joaquin rapid intensification from a tropical storm to a Category 4 with 130 mph winds. But one of their newer, more detailed models at the National Hurricane Center got that part right. It's called the HWRF. Here was a forecast from Sept. 30.

Like the earlier map, the closer the lines are together, the stronger the wind. It tracks Joaquin from the Bahamas to the North Carolina coast by Oct. 4, still as a major hurricane. Most models had tracks with landfalls from South Carolina to New England, although not as intense. So, what if this forecast was basically right, and Joaquin made a left turn into, let's say, the Chesapeake Bay, or even into Delaware?

THE WORST-CASE SCENARIO FOR OUR AREA

As we learned with Sandy, a hurricane moving in from the east is way worse than the typical track up the coast. The perpendicular track allows the ocean waves to build over hundreds of miles or more, eventually pounding the coast with a big storm surge. It was the surge that crippled the beaches from North Jersey to parts of Long Island, NY.

Sandy didn't do that to South Jersey or Delaware because it made landfall near Atlantic City. Those areas were hit by the "weaker" side of the storm. A Joaquin track toward Delaware would put our beaches in the crosshairs. The Sandy damage we saw would have been trivial compared to what Joaquin could have done.

Remember, the pressure gradient itself already was producing gusts over 50 mph at the shore and major coastal flooding while Joaquin was still in the Bahamas. Imagine two or three more days of water buildup, with 120+ mph winds pushing water toward our beaches. Yes, Joaquin would have weakened by the time it came up this way, but it could still have been a Category 1 or 2 hurricane. Remember, ocean temperatures were near record levels (for this time of year), above 80 degrees beyond North Carolina. It's not hard to imagine a 100 mph hurricane at landfall.

Coastal flooding would have set records. Ocean water would surge right up Delaware Bay and into the Delaware River, flooding parts of the Philadelphia and Camden areas that never flooded before. The torrential rains would add to the flooding at the shore and inland. Winds at the Delaware beaches and South NJ shore would gust up to 100 mph, causing extensive damage. Wind gusts in the Philadelphia area could reach about 80 mph, causing tremendous tree damage (and leading to massive power outages).

The storm surge would make some South Jersey beaches look like what Sandy did to the North Jersey beaches. Big dunes on Long Beach Island would help protect much of that island, but smaller dunes could be destroyed, allowing the water to race inland, causing even more flooding. Anyone staying on the barrier islands would be trapped, at best. The ocean would meet the bay in places like Margate, which has no dunes for protection. The Delaware beaches would see destruction that they couldn't have even imagined.

"WE DODGED A BULLET" - THAT'S PUTTING IT MILDLY

After Joaquin started moving out to sea, one of our anchors said to me: "Well, it looks like we dodged a bullet." Knowing what could have happened, I replied: "It's more like we dodged a nuclear blast." OK, maybe a bit too far — but not much. The loss of life would likely have been higher than what South Carolina saw (again, even without a direct hit). And the damage would probably have been more than $50 billion. Even the most rabid storm lover should have been grateful that the European computer model was the only one that was right, pushing Joaquin out to sea. Thank God it was right…..

Glenn "Hurricane" Schwartz

Chief Meteorologist, NBC10 Philadelphia