Posted by Chris Lambert
The pieces to the forecast puzzle on Sandy continue to come closer together and the latest model data to analyze suggests that Sandy becomes a high impact storm for the mid-Atlantic and/or New England.
The 5:00 AM update from the National Hurricane Center has Hurricane Sandy coming off the coast of Cuba with winds sustained at 105mph. Sandy is expected to move into the Bahamas later this afternoon and emerge north of the Bahamas by Friday night.
Notice the 5-day track? There is a turn to the NE by Saturday, and typically, that’s the point of no return, where storms head out to sea and never look back. The typical kicker out to sea is a west to east jet stream that accelerates storms across the opens waters of the Atlantic.
Therein lies the problem this go around. The jet stream, by Monday, won’t be west to east. More and more computer models now insist that a massive area of high pressure builds in south of Greenland and just east of Labrador, blocking the pattern. It’s what we meteorologist refer to as a negatively indexed North Atlantic Oscillation (-NAO). When it’s strongly negative, it can coincide with the jet stream upstream (across the eastern U.S.) buckling.
As a piece of energy rotates in around that buckling jet stream, just at the right time across the eastern U.S., Sandy may actually phase with that upper-level energy and move back toward the coast. As this occurs, Sandy, turns into more of a massive Nor’easter, provides an expanding wind and rain field that produces damaging gusts, flooding rains and coastal flooding over parts of the mid-Atlantic and/or New England anywhere in the Monday-Tuesday timeframe. This scenario is now more likely, and over the next few days, we will be ironing out the details. Although, the timing of all these ingredients coming together has to be precise, so there is still a chance of a miss to the east, but that chance has lowered.
The exact positioning of the incoming low/Sandy (I think it’ll likely keep the name as it becomes more of a hybrid storm… warm core may stay intact) will matter in a sense of wind direction and intensity impact for us.
A path that lands either into us from the SE or just south of us from the SE would create widespread onshore winds that frequently produce 50-60mph speeds, gusts to hurricane force at the coast (74mph+), severe beach erosion and severe coastal flooding, inland flooding from torrential rains and widespread power outages due to downed trees and tree branches.
A path that takes Sandy into the mid-Atlantic or into Northern New England/Canadian Maritimes would have a lighter impact here. We’d still deal with some coastal flooding and beach erosion, but it’d be minor. Wind gusts at the coast could push 40-50mph, causing isolated power outages, but wind speeds inland would likely be in the 20-30mph range. Rain causes localized flooding, but not as much rain falls.
Obviously the stakes are high with this storm but the potential is there for a damaging storm. We’re still 4-5 days out with plenty of details to iron out including the direct path.