Thanksgiving Eve Coastal Storm

So... Snow is possible... how much?

The Setup:

  

 Snow is expected to fall on Wednesday. How much and how long has yet to be determined. This is quite a marginal setup, requiring us to get many things right in order to get good, sticking in the metro area. Areas to the west probably will have a better time with getting sticking snow due to their elevation. In any case, this storm has the potential to really screw with our Thanksgiving  travel.

 

Sighs Model Differences:

The computer guidance (models) are still all over the place. The Canadian (GEM/CMC) brings the storm way east and out to sea (OTS) while the European model (ECMWF) brings it just off the coast. Even the similar models, the GFS and the Parallel GFS, have vastly different solutions. The main difference beween the GFS and the P-GFS is  that the P-GFS has higher resolution. They both run on the same physics principles. The main issue is the difficulty in resolving the strength of the coastal low. For example, the Euro brings the storm west because it amps it up a lot off the coast, which keeps us a bit on the warm side. The P-GFS depicts a scenario where there is a low over the Great Lakes, which disrupts our developing coastal system. the Operation GFS is similar to the Euro, which lends credence to the more amped solution, which is more ideal for us. One issue that all models show for us is surface temperature issues. Our temperatures will likely start near 40, dropping with the onset of heavier precipitation. Since there is a lack of true cold air near the storm, the storm will have to manufacture its own cold air through a process called dynamic cooling.

A comparison between the Operational GFS and the P-GFS

In Conclusion:

While we have a pretty decent chance at some accumulating snow, we still can have some improvement  to the scenario. The setup isn't perfect; the lack of a truly cold airmass to our NW is worrying. We are currently dependent on heavy precipitation to save the day although there are signs that high pressure may develop to the north, injecting cold air into the storm. Otherwise, we could just get white rain or plain rain, with no accumulation. Th most likely scenario is rain/snow in the morning changing to snow with 1-3 inches of accumulation in the metro area and 2-5 as you go towards the more rural areas to the north and west.