First and foremost, our storm is really taking a toll in the Southeastern US. Snows and ice are really hitting an area hard that is not normally accustomed to this. I can only hope everyone down there follows their forecasts and have plans done accordingly.
For our area up here, we are about 10 hours away from the start of our storm. As you can see, we are dealing with a very large storm. We can see a direct influence from the Gulf Of Mexico feeding directly into our low pressure. This will be a very intense and large storm. This will also probably be our longest duration event for the year.
My going thinking has been 4-8" for the area and then a switch over to a mix and possibly rain. I do think we switch back to snow as the CCB (Cold Conveyor Belt) swings through the area. The CCB is the back end of the "comma" head of the storm. As the storm pushes through, this will swing over the area. How much additional will that add? Well, like everything else with this storm, it depends.
I will say, the models have been all over the place with this very large and complex storm. My 4-8" is my best guess trying to make sense and from experience with these types of storms from prior years. Growing up in NJ, most of the large intense storms bring a period of a transition to a mix or rain. As the storm moves east of the area, we go back to snow till the end of the storm. While the model guidance has been less than stellar, I do hold out hope for the short range models, the HRRR and the RUC models which will be in their range later on tonight.
While my call is 4-8" with a transition, the confidence of that is low to medium. I think we are going to see some very impressive snowfall rates through the area. We have a storm that is going to dump between 1-2" of precipitation. The question is going to be figuring out, how much of that is snow, mix, rain. If it were all snow, we would be looking at 12"+ easily. Now, how fast do we transition? Do we transition? does it stay as sleet? freezing rain? rain? Do we go back to snow? What kind of precipitation rates do we have? These questions will all be answered starting in 10 hours. Until then, I am going with the 4-8" as my conservative estimate, with a strong feeling that the totals may end up higher than that.
So, while those are the accumulation questions, there will be other questions that will also need to be answered. I said that we are dealing with a very large and dynamic storm. Even if warm air moves in, and the surface temps get above freezing, if we have a period of very heavy precipitation, we can remain snow if the upper atmosphere is still below freezing. This will all have to be tracked as well with the storm. Obviously, if the rates are not that impressive, or the upper atmosphere and surface are above freezing, we will have rain. Speaking of dynamic......I fully expect there to be a good number of reports of thundersnow tomorrow. Maybe even as early as the early morning hours.
So, the specifics.
Snow moves in around midnight to 2am. It will snow very heavily in the early morning hours, with the possibility of thundersnow. Accumulations by the time we wake up will be 3-6". I expect to pick up another inch or two and then a transition to a mix will occur as the storm moves closer and some warmer air floods the upper atmosphere. I do think though we will remain sleet for a while. During the afternoon, precipitation may actually stop or become very drizzly. To the evening hours, I expect the CCB to intensify and move through dropping more intense snowfall before ending towards midnight. Exactly how much will depend on how the low pressure bombs out, and how much moisture can be thrown back over the area.
Anyways, those are my thoughts and concerns as of now. As always, I will be posting on facebook and twitter throughout the day and night.
Stay Safe!
