The secret to comedy

Timing! The same with this storm (Thu-Fri). Much has to do with the timing of the two shortwaves phasing, as well as the front exiting the east coast.

The GFS has been quick to phase energy in the south and have it ride northward, before the front is sufficiently off shore for cold air to infiltrate the region.

The NAM has the front clear much of the east coast with a 500mb low festering in the Gulf of Mexico at 84 hours.

In addition to timing, another factor to watch is how amplified the models make the shortwave entering the great lakes on Thursday. For instance, the 12z Euro displayed the main storm system closer to the coast which would make precipitation type a problem all the way up to the Mass Pike. One of the contributing factors to this change from the previous runs was that it amplified the shortwave to the west more which then pulls the coastal low west. Model runs yesterday had this clipper moving east quicker, which would present a reinforcing shot of cold air. In addition to this change, high pressure in southeast Canada was weaker and scooted east much quicker, eliminating cold air damming.

One very interesting aspect of this storm so far is that it is bringing out the biases in models. The GFS has a tendency to phase too quickly, the Euro has displayed a bit of a warm bias, and the NAM, well, it's just a bad model.

Needless to say, there is a lot of disagreement among models / model runs. One thing that has been consistent so far is low pressure riding north along a dying front off the coast. There hasnt been any model yet to show low pressure heading inland. This indicates good potential for a winter storm for at least some portion of New England Thursday into Friday.

I think the models will begin to have a better handle on this event by the 00z runs Tuesday which will come out late tomorrow night. This is because the shortwave associated with the Wednesday frontal passage will be onshore in the west where there is more concentrated data collection.

There is a reason it's called "threading the needle" - many things can go wrong to produce a miss or rain. Some might call this comedy.