This has not been a good day for snow lovers in terms of the model data. As I have previously noted, when I speak of "model data" I am referring to computers programmed with algorithms to predict how the weather will react in the future based upon the input of current data analyzed in reference to historical outcomes. The various models are programmed differently and current data is input to each at various times throughout the day. So, within a day, as more current data is fed into the system, differing outputs occur.
I mention this as the models are continuing to shift things around for us. You know I have been mentioning Wednesday's snow potential for some time now since the models have been very consistent in keeping the storm. Well, on Tuesday the models either took it away or greatly reduced it. Why? I'm not too sure, but I do believe that part of the answer lies in their inability to cope with the temperature issues in the varying layers of the atmosphere. As I mentioned in my previous post, the upper atmosphere is cold enough for snow, but the surface is a bit too warm. Here is how I see Wednesday.
TIMING: Precip beginning in the afternoon lasting through Thursday morning.
PRECIP TYPE: For those in S MD I believe it will be primarily rain, although a few snow flakes could filter in, if you look closely. For the rest of central and N MD the rain will eventually change over to all snow.
ACCUMULATIONS: I will slightly cut down my numbers from my previous post, saying those around Baltimore could see a dusting to 1" while those closer to the MD/PA line and W could see on average 3".
PROBLEMS: The main issue is the ground temp and the rain. My numbers are based on the rain changing to snow late in the evening. The longer the rain holds out the shorter time frame for snow and so less snow accumulation. Also, more rain means a warmer and wet ground. Therefore, the first batch of snow will melt, cutting down on the accumulation totals. So, if the change over happens earlier and the snow falls heavy, we could see more snow than I am saying. What are the odds? I don't think the odds are great. I do believe that the ground temp is working against us this time, so I am sticking with my numbers.
SATURDAY: Referring to my discussion above on the models, the major models, on Tuesday, took away the Saturday coastal storm. But, not to fear, this is typical behavior for models this far away from the actual event. Keep in mind that the models work off of current data, and the system that will help produce Saturday's storm is still in the Pacific Ocean. For many reasons I do feel Saturday is still good for snow for us. Currently the local NWS has us at a 20% chance for snow, but in their discussion to the forecasters they talked about it being too warm for snow on Saturday. I respectfully disagree since all the model data, even taking away the snow, keeps us in temps below freezing just above the surface. So, I will keep an eye on Saturday and see how it shapes up.
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