I’m going to do a post on the big storm everyone is talking about, now what I want to emphasize here is the word POTENTIAL. This is not an official forecast , this is just laying out the possibilities and what I think is going to happen as of right now. Keep in mind the time frame for this storm is still 5-6 days away, so plenty of time for things to change
A very complex pattern will be setting up this week and weekend that will lead to the potential for something very big to occur along the east coast.
Tropical storm Sandy (which developed as of 5 pm yesterday) is currently spinning just south of the Bahamas and moving slowly NW due to the ridge building over the east.
Meanwhile a very strong cold front will be approaching the east coast by the time we get to Sunday, and depending on how these 2 interact, or if they interact at all will determine whether we just have a cloudy and cool weekend or do we have a MAJOR storm system with tropic storm ad hurricane like conditions?
The NAO is a big factor here, without it going into a deeply negative state there is no potential for this storm what so ever and Sandy slips out to sea with no major impact to the east coast.
The cold front will have a trough associated with it, and this negative NAO will force the trough to go into a negative tilt, or in other words it is oriented from SE to NW, this will be one of the keys in pulling the storm towards the coast. The more tilted and deep this trough can get, the better the chance for a huge east coast storm
The general and simplified idea here, is that Sandy interacts and phases with the trough and polar jet stream gets pulled up and then into the coastline from SE to NW, and Sandy would likely transition to more of a hybrid or cold cored system through this process.
Another factor in determining just how tilted and deep this trough will get is the PNA
In order to get a deep trough in the east you need the PNA to be positive (which means ridging is evident over the western US) and we can see during the time frame of the storm the PNA is expected to be transitioning from negative to positive, keep in mind many of our biggest storms occur when the telecoonections are in transition so you can probably see where im going here
We have a very large model spread going on, the Euro/Canadian models are all showing this huge storm impacting the mid atlantic and NE US , while the American model (GFS ) has it going out to sea harmlessly
I’m going to start here with comparing the GFS model to the European model (by the way both solutions are both very possible)
The main difference here is the ridging in the western US , the GFS model has a ridge but its much flatter and that leads to a flatter and more neutral oriented trough in the east, a neutral oriented trough or a weakly negative tilted trough will not pull the storm NW and lead to much less of a chance of the polar jet stream phasing with Sandy and so the storm doesnt move NW into the coast line but instead allows Sandy to go north and then eventually NE and out to sea with nothing but a cold front coming through Sunday
The European however has a much more amped up ridge in the west, and its also a bit further east which helps, but the bigger and more amped up ridge allow the trough to really into the east and become negative tilted with help from the powerful negative NAO pattern, Sandy interacts with the trough, the trough pulls the storm NW and you get this
Yes, a hurricane or at least a hurricane – like storm ( it could be more cold cored) barreling up the coast and eventually turning NW into the NE US coastline
Keeping in mind the GFS bias of being to progressive and weak, and the European models strength in tropical forecasting I am leaning toward the Euro /Canadian camp right now, especially since the latest GFS is showing signs of going that way too.
We have all the right ingredients to get something like this HOWEVER these ingredients have to interact perfectly and interact in a timely fashion, which is why we don’t see storms like this very often and keeping that in mind , the out to sea solution can not be forgotten
The best thing we can do is just continue to watch the overall weather pattern, satellite pictures and the model guidance over the next few days to see if this becomes a threat , so there’s no need to panic , theres a lot moe time to watch this and for things to change but just keep this in the back of your mind that we COULD be dealing with a serious situation by Sunday and stay tuned to later forecasts. This post is just advertising the POTENTIAL ( theres that word again!) of a major storm system