Storm Potential Very Much Alive For Week of December 11th

While admittedly there are three different scenarios on the table for this upcoming event on the three different global models ..the one thing that they have in common is that there is going to be a storm system somewhere in the East. In other words if this is a fantasy storm then all three models are sharing the same hallucinating misconception.

I have heard comments that this storm will disappear on the next run of the GFS ..and as if to put those comments at rest the GFS still had the storm. Still a powerful storm as well.

One thing seems certain a storm is coming but the details at this range are next to impossible to figure out. We can only look at the guidance and try to determine what is the most likely scenario to occur.

So lets look at the two main operational models and then we will take a look at the ensembles of the ECM as well. Again..more emphasis will be placed on the European Model because despite some misinformation on the net that model still is beating every other model when it comes to verification time.

18 Z GFS essentially had an all out blizzard with 1-2 feet of snow. So lets see what the 00z GFS said:

Now the first thing i want to point out is that the GFS essentially beyond 180 hours switches to a lower resolution. Notice where the low is at 180 and then look at the extreme jump east by 192 hrs. Do you see that? This I believe is due to that resolution switch.

However..the first things one notices is that this particular run is south and east of the 18 Z run ..however..cold air is in place…and though it is south and east it still effects parts of the mid atlantic into the Northeast.

Switching models we will look at the operational ECM first.

The European Computer model also has a big storm along the east coast but develops an inland runner which actually tracks OVER the Appalachian MTN chain. While this has happened in times past (very few) , weather history has taught us that systems either tend to pass 100 miles to the west of the MTNS or 100 miles east of the MTNS ..so the operational run of the ECM becomes highly suspect at this point and time..This means we have to turn to the ensembles to see what they are showing..so here we go:

Now as you can tell looking at the ensemble means you see that the storm is weaker then the operational model..This is pretty natural considering the mean is made up of multi members and its smoothed down..but you also notice that the system is further to the ENE at 192 hours and definitely much further east at 216 hours as it is off the coast instead of over the coast.

The next thing you notice is that the means are once again colder then the operational run.

So, taking the means and setting them to the side..when one looks at the 00z GFS which is south and east and one looks at the ECM which is an inland appalachians runner…one would generally take a blend of those two models and if that were to happen you would then be looking at something similar to the ECM ensemble means where the storm system would most likely pass across SNJ and Northeast along the coast from there! This would not be good for our SNJ friends but basically pretty much elsewhere would be dealing with a potential significant snowstorm.

What this storm system is going to come down to is highly dependant on the first clipper system in the 120-156 hr range in which it becomes the 50/50 low. Also if the confluence relaxes across the Northeast as the models indicate. The NAO is negative and the AO is neutral heading to negative! There is also blocking in place.

So the pattern that is in place is indeed very favorable and the potential for the first wide spread significant snowfall is very much alive and well for the week of December 11th. Stay tuned for further updates and you can always find the latest tracking coverage at the R.W.S weather forums!