1ST GUESS SNOW FORECAST MAP FOR FEB 9
FIRST GUESS FORECAST MAP
After some massive flip flopping by the operational GFS amnd some syb poart permformance by the GFS ensembles on Monday the midday Tuesday data is much strionger on ALL the models. Even the European model which had some of the weakest or lowest snow accumulations turned colder and snowier on the 0z Tuesday run
Many folks south of the Pennsylvania Maryland border are a little skeptical with regard to the fact that it's going to snow significantly on Thursday, February 9 over some portion of the northeast. But that IS based on the perception that it's amazingly warm over much of Maryland Delaware and Virginia right now and that these warm temperatures extend north of the Pennsylvania Maryland border. But that is a misperception because the warm temperatures over the lower Middle Atlantic states do NOT extend north of the Pennsylvania Maryland border.
This is important because it means that when the cold from arrives on early Thursday morning before dawn the temperatures don't have nearly as far to fall and as a result the atmosphere can cool off much up th rapidly north of the Pennsylvania Maryland border.
. The issues of uncertainty are
1) the track of the LOW
2) how much warm there is on Wednesday and how far north does it get?
3) How fast does the cold air come in as the precipitation is falling.?
There is undoubtedly going to be a significant area of heavy snow over Northwest Connecticut the western third of Massachusetts into much of New Hampshire and the western or southwestern third of Maine. These areas could see over 12 inches. Boston could see that much but I am not certain about that just yet.
New York City and northern New Jersey as well as Philadelphia will start off as rain in the predawn hours of Thursday but the model data is strongewr with the cold air and changes over to snow by 6 or 7:00 AM northwest to southeast. The ground temperatures there are warm and the ground will be wet so it will take some time before accumulation begins. But the model data shows very strong vertical velocities over these areas and it looks it will snow into the early afternoon over southeastern Pennsylvania and Southern New Jersey .. late into Thursday afternoon over interior southeastern New York Northern New Jersey New York City and Western Long Island. This could be one of the snows where the urban areas sees a lot less snow then what the colder surface -- grassy lawns trees bushes cartops... see. For example central park in New York City could end up seeing 6-7 inches of snow but the urban areas see only a slushy 2 inches
Probably area biggest uncertainty has to do with central and Southern New Jersey into the Philadelphia metro area and the northern half of the Delmarva. I think the deformation band will set up over this area but it's quite possible that a slight change in the track of the low would mean that the dry slot over Virginia could reach into Southern New Jersey which of course would drastically alter this forecast for that area.
There is also some variability in the suburbs of Washington, DC and Baltimore up to the Pennsylvania border.