Tuesday Storm Update: The Preliminary Forecast

Summary:

• Winter Storm to effect  most areas of the region Thursday
• There still is a decent degree of uncertainty with this system in terms of how close to the coast it gets
• My thoughts are this comes a little more west than currently modeled
• This means coastal areas can see significant impacts and the I-95 corridor has the shot to see a decent snowfall event
• This will be a powerful storm just offshore so any shifts will have big impacts on this forecast
• Storm would start early Thursday morning and end Friday
• It will be a cold storm so any snow that falls will accumulate quick, be light and blow around
• Expect high winds near coastal areas and high wind gusts just inland as this storm cranks up
• Big update tonight at 7pm

Good morning. This was not easy to do this time but given we are 48 hours away from the potential event I needed to put out an initial forecast. A big disclaimer here is that this forecast is based on current model guidance shifting a little bit more west. If that does not occur this forecast will be wrong. However, I think it is important to let you guys know where I think things are going now where they currently stand in model land.

So here you go...

If my thoughts are correct snow would overspread the region early Thursday morning and pick up in intensity as the day progresses, especially near coastal areas. This storm will be very powerful offshore and reach a very low pressure level. This means we can see gusty winds inland and higher sustained winds along the coast especially in eastern New England. Temperatures will stay very cold so this will be a light fluffy dry snow. That means blowing snow is possible and roads will deteriorate quickly. This also means snow ratios will be 15 to 20 to 1 in many areas. 

Current models for the most part are not as aggressive as my forecast....

GFS...

European...

NAM (closer than others)..

Canadian (similar to NAM)...

So am I just wishcasting or do I have a reason I think this storm trends a little more west similar to what the NAM shows above?

Well given the complex and extremely dynamic nature of this storm the models in my opinion are struggling with how they deepen this energy off the east coast. The result is to jump the low pressure more out to sea than what might actually happen. This is something called "convective feedback" which I will admit is an overused term but I really do think it applies this time.

Below is an example. You are looking at energy at 18000ft to form this storm. Notice how in the last 4 models runs the energy has been jumping all over the place but at the end starts to tuck more into the coast...

This is the model starting to correct to a more compact system that forms closer to the coast on the natural baroclinc boundary of warm water and cold air to the west. If we see other models catch on to this then my forecast will be in good shape. If not then I am completely wrong here. But I am trying to forecast not modelcast. Given we are still 48 hours away small changes to how this energy is consolidated will have big impacts. A 50 mile shift is nothing but a pin prick when it comes to this.


Stay tuned, big update tonight at 7pm. Today's models should tell the tale if I am right or wrong.