Major New England Storm System Possible Early Next Week

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It’s already being called the Perfect Storm but confidence remains low on what is certainly shaping up to be a major storm system that is still a week away from the U.S. East Coast.

There are two sides to this developing storm system. First, the confidence level of the forecast. We’re indicating the confidence level as low because the best computer models are offering different solutions, and this is still six to seven days away. In the world of numerical computer modeling, things can change in six hours let alone six days.

Second is that two significant weather features must combine, and combine with the perfect timing to bring about this major early-winter storm. Timing is everything, as they say, and this potential system is case in point. If the low arrives too early, or late, or tracks in such a way as to be too far off the coast it won’t have the dynamics of the frontal system to allow it to quickly strengthen as expected.

The European model indicates a 926 mbs low off the coast of Long Island Halloween morning, however, the model is known to overestimate. Remember too, this is forecast nine days from now. Click to enlarge. ECMWF image via Raleighwx

Weather Feature #1 is a low pressure area now in the southwestern Caribbean. We’ve been tracking this as Tropical Disturbance 60 since early this past weekend. Now Tropical Storm Sandy, the forecast calls for a north-northeast movement as well as a slow strengthening trend over the coming week. By the weekend, with the low offshore the Mid-Atlantic states, it should transition into an extratropical low. But at the same time, the strong early winter cold front we’re referring to as Weather Feature #2 is expected to move off the coast with enough instability to allow the low pressure center to explode into a significant storm system with abundant rainfall potential. This is why the ImpactWeather StormWatch team is concerned that this scenario may produce one of the strongest low pressure centers of the season.

An extratropical low pressure center moving northward from the Caribbean will combine with a well-developed cold front moving eastward from the Great Lakes so that by Monday significant rainfall is possible from Delaware to southern New England. Additionally, lake-effect snowfall is likely to exceed several inches across western New York, Pennsylvania and West Virginia. This image is for Monday, but the low is expected to continue northward along the coast for another few days. Click to enlarge. Image: ImpactWeather

How strong? The most recent European model (ECMWF) is indicating a 926 mbs central low pressure off the coast of Long Island by Wednesday morning. Though this model is known to overestimate long-range low pressure systems, consider that 1993’s Storm of the Century had a lowest pressure reading of 960 mbs. 2010’s Snowmaggedon (aka: Snowpocalypse) recorded its lowest pressure as 978 mbs. Both of these storms recorded record-breaking snowfall amounts and though next week’s storm is not expected to produce widespread snowfall, it’s expected to be more a rainfall event as temperatures in most places are not yet expected to be cold enough for snow. That’s not to say that several inches of snow just in time for Halloween Trick-or-Treaters is not a significant snowfall, but the snow should be confined to the southern snow belts of the eastern Great Lakes.

Rainfall could exceed 10 inches in many areas from Delaware to New York and southern New England. Sustained winds could be as strong as 35-40 mph, with higher gusts. The winds and rainfall could lead to an ongoing flooding situation as well as widespread power outages.

Again, this is the first notice of a long-range weather situation that might result from the combining of two weather features that, as of now, are in the development stages themselves — a lot could happen between now and then. At this time, the key to all of this is that all of the major computer models are hinting at something coming down the pike early next week, with it seemingly centered over the Northeast. For now, it’s time to begin thinking about preparations for the storm (what’s the status of your emergency kit?) and to keep an eye on this weather situation to see how these features develop.


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