Monday, December 12, 2011

Model Wars - GFS vs GEM

I found a potential weather system that could be impacting our region by the beginning of next week. In this specific series, I want to follow these two, what I call, medium to long-range model forecasts and their interpretation of the existing data. As an extra bonus, I decided to throw in the ECMWF at the end of this discussion.

A brief introduction is necessary along with the 'cast' that may be playing a role in this potential system.

The maps I'm about to show you are from the GFS and the Canadian GEM-GLB models. Both models are on board that a southern storm system could develop along a strong cold front that may impact our weather here in the next 7 days or so.

Here's the cast of main characters to look for:

1) Cold front in mid-section
2) Developing Low along Texas coast
3) Strong SE ridge of high pressure

First, the GFS model, initialized Sunday evening December 11, for the period of December 20-21



Primarily a rain event for the area as the SE ridge pumps warm air into the area but shows signs of breaking down and moving on.


GFS moves the system on outta here with colder air coming in behind the system.

Next, the GEM for the same time period initialized at the same time as the GFS.


The SE ridge pumps moisture from the south, creating an all-rain event at the outset. Again, ridge breaks down and moves on...colder air filters in behind the front.

Ah, an ominous southern track that could create wintry problems around here according to this model run. With cold air in place, low rides along the front, creating a potential wintry mess.

Here's a look at precip types according to the GEM for the same time period (Dec 20-21)


Again, all rain along the front...notice a low taking shape down south.

Rain, sleet, and snow setting up, where else, across the battle zone of winter to be or not to be, an all-too familiar scene.

Now, you know these models will change over the coming days. But I posted this so we can see who has the better idea on this system this far out.

Coincidentally, the ECMWF has maps out that go this far out. It too shows a Low from the south, riding up the front that basically slices Kentucky in half, diagonally with rain to the south and southeast and a snow/mix north and northwest.

In another day or so, I'm going to present more models and their thoughts about this potential storm system, including an update on the two that I featured here, the GFS and the GEM.

MS

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