Hurricane Irene Adam Sobel, Suzana Camargo, Hui Shi, Columbia University

Visual summary of Irene’s track,intensity, size and appearance

Maximum wind,minimum pressure

Satellite image whenIrene was category 3 (near max intensity)

Model forecasts Different curves show results from different computer models. These forecasts were made on August 24.The track was forecast remarkably well; the intensity forecasts tendedto predict a stronger storm than actually occurred.

Sea Surface TemperatureA rule of thumb isthat tropical cyclonesneed the SST to beat least 26C in order to form, or to maintain their strength.

Satellite image justafter NYC landfallIrene had become quite Asymmetric (non-circular) but still had an eye, despite beingonly tropical storm strength atthis point

Radar image atNYC landfallRainfall was focused on thenorth side as Irene Encountered a cold front over land on its northwest flank.

Wind fieldA full barb is 10 knots, half a barb is5 knots; add up the barbs to get thewind speed at any point. 1 knot is1.15 mph. This wind field is anestimate based on satellite imagery,from when Irene was over the NewJersey coast.

RainfallThe left plot is from satellite estimates (in mm), the right is fromrain gauges (which is why it shows nothing over the ocean). Bothrepresent total accumulated rain from Irene’s passage.

Storm surgeThis plot shows the waterlevel measured by the tidegauge at the Battery. Thepeak storm surge was about4 feet above the normaltide. It happened to be aSpring Tide, higher than usual anyway.

FloodingThe most devastating flooding, particularlyin upstate NY and New England, was fromrainfall. This image shows the sediment plume in the Hudson River and NY harborfrom all the flooded streams that draininto the Hudson.

Have there been other storms like Irene?Yes. Floyd (1999) had a very similar trackto Irene’s, shown above right. The 1938Hurricane’s track is shown above left. That one was different because it came directlyfrom the ocean, not making landfall beforereaching the NY area as Irene and Floyddid. Because it moved fast, the 1938 stormwas able to stay strong (category 3) as itcame over the colder waters off Long Island.Irene moved much more slowly. Because ofits large size and slow motion, it was clear early on that the danger in our area fromIrene was rain and storm surge.

Rainfall from FloydCompare to Irene, on the middle panel..

1938 Hurricane Floyd (1999)_