Tropical Storm Sandy potential New England Impacts

The meteorology world has been buzzing about a potential storm system impacting the northeast next Monday, Tuesday, and Wednesday.  Most forecasters have tried to hold off issuing any dire announcements or declarations about this system because it is just too early to be sure of any specifics.  However there has been too much consistency from some of our weather models and quite frankly the solutions of several of these models are downright scary.  Rather than alarm anyone I feel tonight is a good time to tell the public what may be coming so we can keep an eye on it.  Here is a breakdown that will be somewhat technical but this will be the first of potentially many blogs on this system.

Overview
Tropical Storm Sandy developed yesterday afternoon in the western Caribbean Sea.  Sandy is forecast to strengthen as she heads north over Jamaica, then Cuba, and into the Bahama's.  Here is the National Hurricane Center forecast track

Hurricane Warnings for Jamaica, Cuba

 Up until Friday at 2 PM most of the computer guidance is in remarkable agreement about this.  In fact, there is roughly a 90% chance that Sandy is a hurricane in the Bahama's on Thursday evening.  For my meteorology friends here are the relative measure of predictability from the 00z/23 model suite.  For causal readers I hope you will be able to read this chart.

The ridge over the east is highly predicted; the diving trough is in the Midwest is not.

In terms of the computer models some of the global guidance (NOGAPS, EURO) and ensembles (EURO, GFS) are indicating that Sandy will try to come north and not escape out to sea, which is favored for October tropical cyclones. However a developing atmospheric block will eject the system to the northwest.  There is also a very cold air mass diving south into the Midwest and southeast from Canada.  Here is the 18/23 GFS 2 m temperature anomaly charts courtesy of Dr. Ryan Maue of weatherbell.com at several points in the next week to illustrate the coming cold.  Note that anomaly charts measure the departure from average so negative anomalies are colder than average and vice versa.

Tuesday 2 PM

Thursday 2 PM

Monday 2 PM

This is a major temperature clash so there is already a strong baroclinic zone forecast, with or without a tropical system.  A big question is how "deep" the trough will dig into the south.  A friend of mine who works for the National Weather Service down south noted that there have been some unusually strong trough's that have dug deep this year.  The deeper the trough the more likely it is Sandy is captured and ejected into New England.  

Related to the trough is a developing block in the Atlantic Ocean.  This "omega" block will not allow Sandy to escape out to sea.  Some models do not have this block being as strong and thus allow the system to meander further out to sea.  However the American Global Forecast System model (GFS) has the system eventually finding its way back towards Southern New England.  From a synoptic and physical standpoint I cannot see Sandy escaping out to sea.  I will not predict strength or impacts this early, nor will I pick a model .  Track is important but this will be a large system.  For my meteorology friends I am leaning towards a hybrid of Sandy impacting the Northeast early next week.  Hopefully the EURO is wrong.

What does this mean?

It means its time to make an emergency plan.  Make sure you have working flashlights, batteries, radio's, water, non perishable foods.  Clear the gutters of leaves on roofs.  If you live near the coast and make preparations for winter storms its a good time to think about when to secure property.  This could be all hype; if that's the case no lives will be lost.  This also could be the real deal, a storm of this magnitude hasn't occurred in generations.  

For what its worth here is the seven day forecast from the Hydrometeorological Prediction Center (HPC), one of the best government meteorological agencies.

Updates will be made each day.  Questions comments tweet me @zgreenwx .