January 22-24 Storm Thursday Morning Update

Good morning everyone, here we are grinding down for the end of the week. In addition, we are looking for a rather significant winter storm to move into the area tomorrow night and lasting much of the weekend. A month ago, a storm like this was the last thing people were thinking about while air conditioners were cranking away. But alas, here we are. So, lets get caught up:

The National Weather Service has issued a Winter Storm Watch for all of NJ, DE and E PA. In addition, blizzard watches are issued for the metro areas around DC, Baltimore and NYC. Reading the daily briefing from Mt Holly, they mentioned the possibility of upgrading some areas to blizzard watches, but had some concerns about the wind aspect for the inland areas. They can always upgrade to warnings later. People hear the word blizzard and think massive snow. The definition of a blizzard per the NWS is a three hour period of winds greater than 35mph and visibility less than 1/4 of a mile in falling or blowing snow. Blizzard warnings do not mean more snow. In any case, here is the warning box and the latest amounts from NWS PHL/MtHolly:

Snow is looking to start around evening through the overnight hours from the south to north. Snow will gradually become moderate and then heavy. As our storm begins to intensify, we will then have to watch the mix line to see how far inland it moves. Most Nor'easter storms will have this mix line in our area, just depends how far inland it goes. This will have to be now-casted Saturday. In any event, if you do mix, it will not be for the entire event, you will eventually go back to heavy snow. For those areas that dont mix, you will have the max accumulations (and a much better shoveling experience). As of now, I think the mix line will make it into S NJ and coastal areas. We will have to watch it though as some models (The GFS in particular) pushes the mix line back to rt 95 for a prolonged period of time.

While there was generally very good model agreement earlier in the week, some really funky stuff has been going on. The NAM model has been spitting out tremendous amounts of precipitation, which it has been known to do. The GFS model has the mix line moving well inland and mixing being a very real possibility from Philly to the east. Not sure I buy into the GFS right now, as the Canadian model tends to overdue warm air, and even that has us primarily all snow. The EURO model is the southern most model, keeping us all snow, but really cutting off amounts to our NW.

There are a number of possibilities, and hopefully some of these things can be resolved today with the assistance of modeling. I have been talking over the past couple days about the upper atmosphere low pressures and where they develop and can "grab" the surface low pressure. When, where and how strong they are will be a driving force behind our forecast. As of now, they have us in a favorable spot for a slow moving, snow making storm.

The other aspect that will challenge accumulations is where the banding sets up. This is another aspect that will have to be now-casted on Saturday. Where these bands set up, those areas will really cash in on accumulations. As those bands setup, you will have areas of very heavy snow and you could go a couple miles away and just have light snow. In any case, at some point many reading this will fall under one of those bands so we should all have the luxury of experiencing it.

Coastal areas, I cannot stress enough about the threat of coastal flooding. Storm surge models are already showing 4-5 foot storm surge as the storm gets cranking and the winds start howling off the water inland. Couple that with a full moon phase and flooding with beach erosion will be a serious problem.

We have a very fluid and changing system coming. And, as always, I will try and stay on top of it and bring you the latest. I put out my accumulation map last night (no flaming, it was my first attempt). As of now, I am sticking with it.

Townerswxpage January 22-24 Storm Accumulations (Click)