Computer modeling on Hurricane Irene has reversed its eastward nudge over the past couple of days and has been on a slow, arduous westward trend for the last couple of major computer model runs. I spoke yesterday about the 100 mile error that computer modeling can have with hurricanes in the four day out timeframe and how that meant nothing was certain (I was optimistic, perhaps wishing, that the east nudge would hold but pointed out that a 100 mile shift would change everything). While the models have not adjusted a full 100 miles, we’ve seen a movement of 50-75 miles to the west since this time yesterday and the modeling outcome has changed a good deal for this region.

A few caveats I’ll put out there.   First, Irene will be a large storm when it gets to this latitude and will impact many (especially if the “close to coast” or inland track verifies) but it should not pack the same intensity punch (Category 3 status) to our latitude as ocean temperatures in this part of the world are lower than they are in the Bahamas.  Hurricanes thrive on hot water and ocean temperatures locally are not conducive to supporting high intensity storms.   Irene will probably not be as strong as she is now but still pack a wallop when it visits us on Sunday.   Second, we probably have not seen the last of the nudges with this storm’s modeled path in either direction and it’s possible that we see a bit more nudging west or east in the coming day or two.

The models have shifted the storm’s projected track to the west, with the Euro taking Irene’s eye up the Chesapeake Bay through the western suburbs and north through the Poconos into Upstate New York after initial landfall in Eastern North Carolina.  Irene could bring near hurricane force sustained winds on its eastern side to South Jersey Shore Points in this scenario, with higher gusts.  Winds in Philadelphia could reach 50 mph in this scenario but the worst impacts would definitely be felt at the Shore from a wind and storm surge standpoint, with everyone impacted from heavy rainfall on the order of several inches.  The surge of water pushing up Delaware Bay would result in potentially significant coastal flooding on southern facing beaches (NJ side) in Delaware Bay and then lead to the risk of reverse coastal flooding on the northern facing beaches (Lewes) as winds veer around after the eye passes by.  The “saving grace” is that the landfall point being in the Carolinas would result in an inland track for Irene.  The result of Irene’s center being removed from the Atlantic for a period of time could weaken the storm some from its landfall intensity.  Definitely an ugly scenario but Irene is not as strong here as in the GFS’ case.

The GFS has a landfall point along the Jersey Shore and tracks the storm nearly over New York City.  This is nearly as ugly a scenario as the models can envision for track.  The storm will have had more time over water (granted, water not as warm but it’s still water and not land) and will be a bit stronger when it makes landfall.   The storm track could result in hurricane force winds hammering the Jersey and Delaware coastlines and bring heavy rain to the entire region.  Winds in Philly are not as strong in this scenario but we get a bit more rain in this scenario as we would be on the western side (rainy) of the storm.

One last point to make this morning:    East of the “eye” will have stronger winds than west of the eye, with the eastern side of the storm providing a better potential for quick spin-up tornadoes compared to the western side.   The west side of the storm provides a better potential for heavier rainfall.   Unless the storm takes a track over 100 miles east of the coastline, the region will see impacts from it…unfortunately, some of those will be rather significant.