Monday, March 14, 2016

Monday Morning Storm Outlook: Winters Final Charge This Weekend

Good morning everyone. Interior New England might  have a winter storm on tap late this weekend! Thats right, latest signals continue to point at possible storm development. This also happens to coincide with larger scale signals we have been looking at such as the stratospheric warming that hinted we could see an active end to March. Before anyone gets too excited, I do not expect any type of winter event along the I-95 or big cities at this time. I am talking about areas of VT,NH,NY State and ME. Especially in the mountains. If verified, this would give all you ski lovers one shot to soak in the winter glory.

So lets dive into the factors at play here and how they need to come together for this storm to develop.

Looking above you are seeing a printout of the latest European Ensemble Forecast System. I highlighted the key features many of which need to be seen for a big east coast storm. We have:

  • A ridge of high pressure out west.
    • This ridge looks to be in an OK spot not a great spot at this time
    • Ideally we want to see the axis a little more to the east to prevent any possible inland runner
  • High pressure or a -NAO over Greenland
    • This is a major factor and increases the chances for energy to consolidate along the east coast
    • Think of this high pressure as bending the jet stream not allowing energy to escape easily out to sea. 
  • Evidence of a low pressure area around coordinates 50/50
    • This is another major factor and usually is the direct result of a -NAO
    • This low pressure center near eastern Canada aids in locking in high pressure over the east coast
    • When you lock in high pressure, you lock in cold air
  • Active northern shortwave of energy diving down into eastern trough as seen by yellow circle
    • This shows that we have energy on the field ready to consolidate into a storm
    • Potential phasing can occur between the northern and southern streams aided by the -NAO
    • This is how you get big storms to develop
So as you can see we have the major factors on the map but that alone does not guarantee a storm. It will be all about how these factors trend and come together over next few days. Similar to cooking, its not just about having all the ingredients but also how you bring them all together that dictates the end result.

The biggest deterrent I see at this time is that western ridge axis being a little too far towards the west coast. Similar to many storms this winter, if we see this become too dominate too far west then we can see an inland runner. 

One additional thing to note about the -NAO. Research has been done that east coast storms tend to occur when the NAO is in transition from negative to positive. The image below shows you how this will be the case this weekend indicated by the yellow circle. 

So now that I laid out the factors we will be monitoring lets look at some models for fun..

The GFS..

The Canadian..

The Euro..

You can see that all models are showing a storm developing. You can also see that they are showing it effecting interior areas with the frozen precip due to the placement of the low. To give you an idea of where accumulating snow is possible lets look at the GFS ensemble mean..

Well this sure will keep the blogging interesting this week. Many more updates to come!

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