Model Mahem: Sandy's Forecast Is All Over The Place

Joe Furey called me this afternoon to have a forecast discussion.  That's never a good sign.  The European model has latched onto this idea of a massive storm targeting the northeast with damaging winds, torrential rain, flooding and storm surge (see below).  This is a low probability, high impact event. Meaning....it would be irresponsible to just "go with" the Euro right now.  But since the outcome could be so potentially devastating, we want to put this possibility in the back of our mind.

Other models are flip flopping on the idea.  Now about half of the GFS emsemble members are on board.  (See below)

The NAO is forecast to tank over the coming days. This would suggest very strong blocking.

This blocking pattern off the east coast is modeled on the 12Z European model below.  Look for the shape resembling the Greek letter omega. An "omega block" can cause a traffic back up in the atmosphere, preventing Sandy from heading out to sea.

If Sandy was forecast to hit CT in three days, I would be freaking out.  But we're a week away! The likelihood that the European model remains the same for the next 6 days is very small.  The timing of the storm needs to line up perfectly in order to phase with an incoming trough.  Otherwise, the trough pushes Sandy out to sea instead of absorbing the storm.

Climatology is important too. Generally tropical storms or hurricanes forming in the vicinity of Sandy take a track well offshore or into the Gulf of Mexico. Especially an October storm!

After the storm moves into the Bahamas (pretty much all the computer models agree on that), we will have the best idea of what will happen next.  At that point our models should begin to agree and we’ll be able to tell you to relax or get ready.