The Hurricane That Flooded Ithaca

25 08 2011

Hurricane Agnes (1972). Image property of NOAA.

Ithaca weather is generally known for cool-season events (blizzards, ice storms and the like). I figured that with the current panic attack starting to set in on the East Coast regarding the impending arrival of Hurricane Irene, this entry is rather timely. Plus, most of my department is having a collective weather-gasm that makes doing work next to impossible (quoting one faculty member, “The Weather Channel has entered [for a disaster-addicted public] total ass-kissing mode”).

Anyways, Ithaca had actually seen some tropical-born activity over the years. I phrase it that way because typically, the storm has weakened into a remnant low or turned extratropical (i.e. becomes more like your standard cold-core mid-latitude low-pressure storm system) by the time the cyclone has passed into and over the region. Hurricane Hazel in 1954, for instance, passed over as an extratropical system with winds still at hurricane strength, but because the Allegheny Mountains wrung out most of the moisture from the east side of the storm, the region was mostly spared (Toronto was not so lucky). Wikipedia identifies 84 tropical cyclones that have impacted the state of New York, and as you might imagine, the majority of these have affected New York City and Long Island.

Reasonably, when a storm transitions to an extratropical state, it doesn’t just stop raining. Occasionally, if the conditions are favorable (i.e. moist environment and perhaps some topographical effects coming into play), the rain can be heavy and prolonged, resulting in flooding. This is exactly what happened with Hurricane Agnes.

Hurricane Agnes was the first named storm of the 1972 hurricane season. As a tropical cyclone, Agnes wasn’t particularly special; about the most unusual thing was that it was a June hurricane, a bit early in the year since the first hurricane isn’t usually until early August. Agnes formed off the eastern coast of the Yucatan Peninsula of Mexico, and moved directly north through the gulf, strengthening into a Category 1 storm with sustained 1-minute winds of 85 mph. The TC (tropical cyclone) made landfall over the Florida Panhandle, moved northeast into Georgia while weakening into a tropical depression, and then passed over the Atlantic and redeveloped into a tropical storm before swinging back west and making a second landfall near New York City with 70 mph winds. Agnes merged with a non-tropical low on the 23rd, and this system impacted the region until it finally moved out late on the 25th.

This was a very dangerous combination. The combined system had large amounts of tropical moisture from Agnes, and was slow moving thanks to the non-tropical low. Therefore, rains of 6-12″ occurred over 2 days, with the highest recording at 19″. In perspective, imagine getting three months of your region’s normal rainfall in two days. The resulting flooding for Pennsylvania and New York was disastrous. In Pennsylvania, 50 lives were lost and $2 billion in damage (1972 dollars) was incurred. The governor had to flee his flooding mansion and downtown Wilkes-Barre was under nine feet of water.

As for New York, the hardest-hit areas were a swath from Olean east to Elmira and Corning. In Elmira, the raging Chemung River destroyed or badly damaged most of the downtown area. One of Elmira’s big industries was railroads and railcars, but the railways were washed out by the storm and the bill for repairs was so high that the railroad companies opted for bankruptcy instead. In my own experience, talking with the older Elmira locals, they say the city never quite recovered from the “Flood of ’72”. In Ithaca, where the rainfall came out to about 7 inches, several bridges in the city and in nearby Brooktondale were washed out and the low-lying areas near several of the local streams were flooded. The lake level also rose enough to flood and damage the facilities at Stewart Park. Thankfully, Cornell and IC were out for the summer, and neither sustained major damage.

Image property of TompkinsREADY

The final toll in New York was 24 deaths and $700 million in damage (1972 dollars). Keep in mind, Ithaca has had worse floods, in 1857 and 1935. But neither one of those had tropical influence.

So, Ithaca is far from the action of the tropics, but not necessarily immune to the passage of tropical cyclones. As for Irene, Ithaca will be on the edge of the circulation at worst, it’s simply too far to the west and under the “protection” of a short-wave trough. But if I were at Weill Cornell, I would be very concerned right now.



One response

26 08 2011
Eric Key

As I recall, this was the storm that washed out the trail from downtown to Collegetown along Cascadilla Creek. This was the year before I came to Ithaca.

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