Friday, December 2, 2011

A Few Things

This post was originally going to be drawn out into two or three separate parts, but I'm going to  bunch them together into one large post.

First, I would like to recap what happened earlier this week. My forecast was, in my opinion busted. Some people say that forecasting shouldn't be personal, but for me, it is. That forecast was not a good one, and I realize that. There are two main parts to why my forecast failed: my own personal errors, and errors within the computer models themselves.

I had been watching the computer models the entire week, and was very surprised to see a eastern trend on the models. This storm was going to be well west of the area for anything signifcant- or so I thought. I've rarely seen a storm trend east on computer models (typically it's a NW trend)- but this was a very complex storm system. It started with a powerful, strong Upper Level Low, which tracked into the eastern Lakes. A 1000mb low followed on the north side. However, I almost would consider it a double barrel low, due to the way the isobars looked. There appeared to be on center over western Lake Erie (and there was one on some  of the RUC runs), and one further east over Lake Ontario. Now, this should have been a red flag, but I did not recognize it. This was where I looked at computer models- which almost all the hi-res models showed the deformation band stalling before it reached I-75. This is why I forecasted 2-4" for areas west of I-75. However, the deformation band actually got to the last column of counties in NWOH, which is why areas like Bryan, Defiance, Ft. Wayne, etc. got the projected 2-4", rather than those further east.

However, there were some bright spots in the forecast. I did recognize that there would be a large gradient over a few counties. I also had mentioned someone in NE IN would get some double digit totals in, and generally got the corridor of the heaviest snow (although again, further east). This again, can be attributed to the actual position of the surface low and the upper level low and how the models handed the situation. I can't make promises, but I hope that the next forecast becomes a bit easier to predict.

This does not appear to be the case, as the next storm appears to be developing within the next 5 days. The global models are all over the place again, and I don't expect that to change anytime soon. Another complex pattern, with a shortwave now over the SW United States, is supposed to eject from a basically stationary trough early next week. This storm is expected to develop along a strong baroclinic zone, and head generally northeast:

Taking a look at global models, the NAM remains the most amplified, and furthest west, resulting in a heavy snow band from Lafayette, IN to extreme NWOH. However, it also is the most lacking on cool air, especially in Ohio. This results in a very wet snow or rain/snow mix for most areas, although a few inches would likely accumulate. The GFS, on the other hand, is much more progressive with this system, showing only a very weak low pressure system. This storm isn't expected to be very strong- because of a positive tilt 500mb trough, GFS is still significantly weaker with the storm- ending with a colder, less snowy solution. The ECMWF is in the middle of these two solution, showing a decent storm north of a line of Defiance to Bowling Green. The UKMET and GEM both develop this storm- but over 36 hours later.

Since it is early in the season, temperatures will be marginal again, leading to another tough forecast. However, I've gotten the rust shaken off me, and I'm back in full forecasting model now. It's officially winter, folks!

1 comment:

  1. Nice post! but can you please change the black page with white words? It really hurts the eyes.

    Thanks

    ReplyDelete

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