Hurricane Irene Threatens Carolinas and New England

As I’ve been privately warning my friends and colleagues in the area all summer, the summers following major La Ninas have been heavily populated with major U.S. East Coast hurricane hits. A few notable examples:

– The “bad girls” of 1954 – Carol and Donna.
– Hurricane Floyd (1999)
– Hurricane Gloria (1985)
– The great ’38
– The 1889 Disaster (the thing that destroyed an entire island near NYC)
– Hurricane Bob (1991 – the first year of a five-year El Nino, but followed a strong La Nina in 1989/1990

I had a rather aggressive forecast out as early as March that this hurricane season would be characterized by high impacts along the east coast (and in Texas…but not the central Gulf Coast), and that there could be as many as 3 major hurricane hits on U.S. soil this season. Well, the ninth storm of the 2011 hurricane season is looking like a doozy. We wasted about three names that never should have been used on short-lived atypical tropical disturbances – a common practice at the NHC these days – but this one is looking like a major hurricane rating is in the bag. A wide circulation is evident on the latest satellite imagery and the storm has well-defined outflow in all quadrants as it passes just north of the Dominican Republic.

The upper pattern stearing the storm is nearly non-existant…it is poised at the SW corner of the so-called “Bermuda High” but the winds aloft are very weak. The storm is expected to move very slowly throughout most of its life time…taking as much as 5-6 days to threaten landfall if it stays on its’ current projected east-leaning trajectory (which I believe is likely). The westerlies are further north than is typical for this time of year with a very subtle weakness in the height field between a high centered over the inter-mountain west and the Bermuda high. The major global models are in agreement out to hour 120 or so as to the relative lack of storminess across the eastern US…the pattern lacks a “kicker” trough to come down and get the hurricane and take it out to sea. Meaning it will likely continue meandering slowly northwestward and only by Sunday or so will it be caught by a much stronger looking short wave trough which is forecast to dig into the Ohio Valley area. At which point…depending on the depth and position of that short wave, the hurricane could turn NNW or due N or even NE, but by then, it will likely already have made landfall somewhere between Florida and North Carolina. I tend to lean more toward the latter than the former.

The pattern is also ideal for the formation of a very heavy rain event in advance of the storm. The scientists dub these “predecessor rain events” and they are capable of out-producing the core of the hurricane for total rainfall and magnifying the flooding impacts of a major hurricane. One such event occurred with Floyd, for example…in DC, it rained for 60 straight hours before the hurricane even made landfall over North Carolina. My co-author will remember the massive flooding and damage this storm caused on the campus of William and Mary as a result of that PRE.

Wherever this storm goes, it’s likely to cause damage on US soil, so I’ll keep the readers posted on its progress as we get closer.

One thought on “Hurricane Irene Threatens Carolinas and New England

  1. Update:

    Our suite of global forecast models are coming into better agreement on the track and even the intensity of Hurricane Irene as it heads for the US East Coast. The trend appears to be east of yesterday's school of thought, with the most likely landfall locations between between Wilmington, NC and Cape Hatteras…with most of the major forecast models leaning to the eastern half of that window. Secondary landfall may also happen on Long Island or the Eastern coast of Southern New England.

    On this trajectory, the heaviest rains would likely be confined to the eastern half of North Carolina and Virginia and then straight north from there into upstate New York and New England. But there is still time for this to change.


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