Irene is strengthening this morning and as of 8am the NHC has officially raised Irene to a category 3 hurricane with winds of 115mph. The most recent aircraft vortex message had a minimum pressure of 957mb and has found flight level winds of 114 knots. This also supports the NHC decision to raise Irene’s strength to a low end category 3 hurricane. Irene’s eye has become very distinct on satellite imagery and it is obvious that Irene is in a strengthening mode. I think Irene will become a category 4 hurricane within the next 24 hours. Eyewall replacement cycles could become common over the next few days so short term fluctuations in intensity will likely occur but the overall trend should continue to be upward.
The overall track philosophy is unchanged from yesterday. Irene is going to head WNW for the next 48 hours or so with a gradual turn to the NW. The storm then will begin to turn north as steering currents weaken. Irene will likely slow down off the southeast coast and will move slowly N and NNE before taking a quicker and more definitive NNE motion as we head into the weekend and early next week. I made a slight east shift with my track today shifting the landfall from Morehead City to more of a Cape Hatteras landfall keeping the center off the mid-Atlantic coast and a 2ndlandfall near the CT/RI border. This would obviously lessen the impact from areas of the Mid-Atlantic up through New York but could deal a very severe blow to eastern Long Island and Cape Cod. There is still some wiggle room for the track to shift west or east. The obvious trend has been eastward the last few days as the trough has trended deeper and quicker.
As far as intensity goes, the storm will likely continue to increase in intensity and I think a menacing looking category 4 hurricane will be approaching the southeast coast tomorrow on satellite imagery. I have seen the HWRF and GFDL taking turns maxing the storm out with a pressure in the 920s off the southeast coast. This type of strength for a hurricane is pretty rare that far north, but I think a storm in the low 930s is certainly possible with winds in the 135-145mph range. As the storm turns north it will start to weaken some, but I am predicting a storm with 130-135mph winds as it passes by Hatteras Saturday evening. The storm will gradually weaken as it moves off the northeast coast, but I would not be surprised to a 95-105mph hurricane at least as it makes a 2ndlandfall in southeast New England. This is tricky and I could be wrong on this end, but it sure seems like this isn’t going to just fall apart as it heads towards Cape Cod. A low end category 3 intensity is possible as well although not likely.
This scenario would obviously be very severe for those in the Outer Banks and southeast New England. The major cities of Philadelphia and New York City could certainly still see some strong winds and heavy rain in this track. The GFDL model is further west and would be a catastrophic scenario for the big cities. Right now that is viewed as an outlier, but I will keep an eye on it.
I will update again around 3 after the 12z data is in.