I’ve neglected to write my customary blog post on Hurricane Irene up to this point, mainly because of the high uncertainty in the track of the system. A few days ago many models were tracking Irene into the eastern Gulf of Mexico and Florida, now we’re finally coming to a consensus on a track that takes Irene just off shore of the Eastern Seaboard, providing the potential for an epic hurricane the likes have not been seen in many decades across the Eastern Seaboard.  Before we get into the potential worst case scenario, let’s start off by talking about the current state of Irene.

Infrared of Hurricane Irene - Taken at 8:25 PM CDT

This infrared image was taken at 9:25 PM Eastern/8:25 PM Central. I should caution that Irene is currently in a period of rapid change, so this image may not be relevant by the time you read this section. Irene has finally popped an eye on IR. Very cold (strong) convection is underway on the northeastern and western semicircles of the storm. Irene has been dealing with downslope from Hispaniola and light shear since this morning, but is finally beginning to move far enough away that both are having less and less of an impact. Never the less, some dry air is still trying to entrain into the storm. This is quite evident in the two highlighted areas on the graphic where warmer cloud tops are noticed. Irene is working to expel this dry air with the strong convection underway, and I do believe that this is becoming less and less of an issue as we continue on this evening.

Irene steadily strengthened on Monday and became a Category 2 hurricane with winds of 100 MPH at about 7 PM Central on Monday. Irene steadied off overnight and began experiencing the effects of passing by Hispaniola and its associated down sloping this morning. Winds fell slightly to 90 MPH, but the pressure has actually kept falling steadily this afternoon into this evening. As of 9 PM Central, the pressure was down to 969 MB. Flight Level winds have increased since this afternoon and surface wind speeds remain around 90 to 100 MPH. The intensity forecast is an interesting one. With Irene currently developing a well-defined eye, it’s possible , if not probable, that Irene quickens her pace of intensification. In fact, some models are showing a period of rapid intensification. As Irene continues moving northwest into the Bahamas, sea surface temperatures and the overall pattern aloft favor a significant intensification. Irene will likely become a major hurricane (Category 3 with winds of 115 MPH) by Wednesday. How strong Irene is able to become depends on how fast it can strengthen in the next two days. At some point, an ERC (Eyewall Replacement Cycle) will have to take place and that will put a hold on any strengthening and Irene will likely top out strength-wise at that point. Because of the extremely favorable conditions, Irene could become an extremely powerful hurricane in the next two days.

8/24/2011 0Z Intensity Guidance - Hurricane Irene

The general consensus among models is to make Irene a Category 3 hurricane within the next day, keeping it in that range as it approaches the Eastern United States. It should be noted that rapid intensity fluctuations (specifically rapid intensification) are not handled well by the models and that would not be depicted on this graphic with much accuracy. We’ll be monitoring the intensity closely, especially over the next 48 hours as Irene remains over an extremely favorable area for intensification. As the intensity is dependent on the eventual track of Irene, the intensity forecast in the long term is uncertain. However, conditions will be favorable for Irene to maintain major hurricane strength for a while. Something to think about is that Irene is forecasted to become a large hurricane with an expansive wind radius. This will allow for the formation of a very significant storm surge and at this point, it is safe to say that some areas along the Eastern US Coast will experience major coastal flooding associated with a storm surge. The closer the core of the storm gets to the coast, the higher the surge. There is the likelihood of coastal evacuations, perhaps widespread across several states, due to a major storm surge, but those specifics are still to be determined.

Hurricane Irene, while currently moving northwest, will soon be pulled more to the north and eventually to the northeast. When this happens and how strong the pull will be will determine what regions of the United States, if any, Irene will impact. Irene is currently being steered west by a strong Atlantic ridge, but a trough will be amplifying over New England as Irene approaches the East Coast. The stronger and farther south this trough gets, the sooner it will yank Irene back out to sea. This presents the possibility of several scenarios. Obviously the track of Irene has a massive impact on most of the Eastern United States. After several days of an eastward trend in the models, they have come to a consensus today. Below is the latest models off the 0Z suite. These are only models and should not be used for making life and death decisions.

8/24/2011 0Z Models for Hurricane Irene