If a storm is trapped in between a weakness to the west and a ridge to the east, the steering flow will largely collapse, with all that remains being the flow between a ridge and a trough -- out of the south towards the north. Coupled with the natural effect of Coriolis upon a storm and the storm would slow down and move into that weakness -- i.e. north and largely away from the shore. Unless he's saying "shore" as "New England", another ridge would have to build in before the storm gets captured in the midlatitude flow for the storm to hit land in that scenario.
Needless to say, most model guidance is now keeping this storm offshore through the forecast period, generally slowing it down but taking it out to sea. NOGAPS shows an interesting scenario of it recurving and heading NE, but in 6 days slowing down well N of Bermuda. Not buying that one just yet. If current trends continue -- the upper-low to the west is largely gone, replaced with a building ridge, but the storm is already into the weakness between the two cells -- my track forecast from the past two days will need to be substantially revised. The weakness created by that upper-low, not allowing the ridge to fully build in and allowing the storm to drift more towards the north, coupled with reogranization of the storm may be the saving grace if it stays offshore. The storm should turn back a bit more towards the WNW still, as previously noted, but it's already about 1deg further north than previously thought (by NHC & on this end). That 1deg could be big. We'll watch it, and a new update may be forthcoming late this evening.
Added: the upper-low dropping south may induce a little bit of "Fujiwhara" mutual rotation with Irene, the tendency of which would be to swing the storm more westward. The upper-low is dropping SW right now; a move to the SE would suggest some interaction. Not too worried about it now, but it bears watching. Nevertheless, Irene is headed for a classical deformation zone/col, where the steering currents are minimal, out over the Gulf Stream. Given the further north track, the position of the trough, and the added push the westerly flow that starts near 33-35N gets from the development of convective systems each night over the upper midwest, I do think a further north -- and potentially land-saving -- track is quite possible after about 3 days. That still places much of the coast from Myrtle Beach on northward in the cone of uncertainty. Stay tuned.
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