Friday, February 12, 2016

Friday Morning Storm Outlook: Releasing My Preliminary Impact Map for Tuesday

Good morning everyone. As we have been discussing, we are tracking a storm that will impact the area Monday night into Tuesday. So many details need to be worked out as usual (as they all say), but I want to try my best to keep you guys ahead of the situation and give you my best thinking. First lets take a updated look at model projections for Sunday mornings temps!



Yes that's sub zero in many spots! Highs all weekend will only be in the teens for many areas. This is the result of the polar vortex coming to town..



Ok back to early next week.

 Here is my first projection on what can happen Tuesday..




We do not currently have the proper set up for a big east coast storm (big cities). This is due to the bitter cold air we will experience this weekend (sub zero in spots) exiting the area ahead of this storm. HOWEVER, in this pink zone the cold air should put up a fight. I expect things to start off as snow Monday night (few inches possible) then transition to ice then finally rain. There is a big risk here cold air can hold on near the surface  especially in the western areas of the pink zone. This means freezing rain and a potential horrible commute Tuesday morning. Rain should eventually take over but not until some impacts are made. 

For the green zone, things should start frozen but I expect a much quicker transition to rain and limited impacts at this time.

The jackpot looks to be the dark blue zone where significant snow accumulations are possible. I will note there is some model guidance that is west of my map which would result in even the dark blue zone getting liquid. At this time, I am trying to show you guys what I think will happen as opposed to just copying a model projection. 

This map will be updated twice over the next 4 days. I will eventually have a snowfall map then tweak it to a final forecast as event approaches.

So now that you have a general idea of what I am thinking, lets take a look at the maps. We have a wide range of solutions here as the models are still struggling to get a handle on this. The image below is my best way of showing whats influencing this storm. The European model is on the left and the Canadian on the right (click to make bigger)..



Looking above a few things to note. Notice how the European model has that southern feature stronger. Also compare it to the Canadian which has a weaker southern feature and more evidence of a stronger lead short wave ahead of this storm. Here lies our forecasting issue folks. The key to the track of this storm depends on what feature ends up being modeled correctly. If the lead short wave as seen on the right image ends up being stronger like the Canadian shows then it will help hold in the cold air longer and also develop a low closer to the coast. If this does not happen as the European shows, we have a warmer solution. This is what we are going to have to track over the next few days.

My forecast map is basically a blend of these two with some input from the GFS model. I also am trying to look at similar storms from history. At the surface here are some model projections for Tuesday morning..

GFS..


Canadian..



As you can see much different outcomes and it all comes down to the features I discussed above!

More later. 

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