Hurricane Irene has weakened a bit more this afternoon in terms of maximum sustained wind speed in the core, but as I mentioned earlier, the main threats are the storm surge and the rain... the exact intensity should not be the focus when it comes to preparations and evacuations. At 21Z today, the maximum sustained winds were 85kts, making it a Cat 2 storm. It is located 265 miles south of Cape Hatteras NC and moving N at 12kts.
I first mentioned this disturbance on Aug 16, one day after it exited the African coast. Now, 10 days later, it's getting a bit more attention! Here is a satellite image from Aug 15 showing pre-Harvey approaching the Lesser Antilles and pre-Irene just west of Africa.
Tropical storm force winds and outer rainbands are already ashore in NC, where landfall isn't expected until early Saturday morning. The radar loop covering the landfall can be found here: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/atlantic/ (in the News & Updates section)
For some perspective on size, if you placed Irene's circulation over the continental US, it would cover Florida up to Pennsylvania, and from North Carolina to Oklahoma. This is a large storm.
There are evacuations in coastal areas from NC up to MA, and wisely so. Even if Irene continues to weaken, the storm surge and rainfall will be extremely destructive. The storm surge is forecast to reach 8' in parts of the Chesapeake Bay, up to 6' in parts of the Delaware Bay, and 3-6' in the NJ/NY area. The latest storm surge forecast for the NJ/NY area is shown below. For the first time in history, New York City is shutting down its mass transit systems and evacuating low-lying portions of the city (300,000 people so far).
Looking back, I was able to find just 12 hurricanes in the past 160 years that had comparable tracks to Irene, many of them notable and infamous. These include Floyd (1999), Bob (1991), Gloria (1985), Belle (1976), Donna (1960), Carol (1954), Edna (1954), and 5 from earlier years when storms weren't given names (1944, 1894, 1879, 1861, and 1858). The plot below shows the east-central portion of the coast with these storms' tracks overlaid. So Irene will be added to this list and be remembered just as these are.
Please visit my tropical Atlantic headquarters.