Saturday, February 5, 2011

Numerical Forecast Models Fail (Again)

Today was a nice 6" surprise (for snow lovers).  But for forecasters, professionals and amateurs alike, it is part of an ongoing problem.  Take a look at Accuweather's forecast for today's snow maker.

It doesn't match up with the track or intensity.  The National Weather Service was very similar in with their forecast.  Yesterday afternoon were some warning signs the forecast might be in trouble.  The intensity was stronger than forecast.  Last minute model changes along with upstream observations sent everyone scrambling.

A Winter Weather Advisory was issued for central Indiana at 2 AM.  Very last minute.  People were pretty much unprepared for the snow.  Many were still digging (or chiseling) their way out from the last one.  The NAM yesterday did a huge shift northwest with the 18z run.  I didn't buy it.

I even made a post about it saying I didn't think the NAM would go negative at 500mb as modeled.  No way it would pull the storm northwest and no way it dumps 6 inches of snow here.  I blew it big time too.

Not to dwell on the last storm too much but the models also had some failure including missing the final track until the very last minute with a northwest shift.  

So given the poor performance of the models, how can anyone trust them?

Looking at tomorrow and Monday, I will make a best guess but will be watching the model trends and the actual performance upstream.  Still though, I am not thinking there will a lot of accumulations with this snow. It will also be much more strung out with some light winds.

Plan for 2-3 inches, mainly Sunday overnight into Monday morning.  Some blowing and drifting as today's snow will blow around nicely.

The bigger question is the middle to end of the week storm system.  Not favorable for us according to the models right now but given the recent history, Anything could happen.  No matter what happens, the week looks to be rather cold.

1 comment:

Chris in Tipton said...

Very eager to see if the low Sunday will wobble a bit northward...IE Saturday's snow. MUCH MORE curious to watch the progression of the storm for mid week. If the northern trend continues yet again....we may be in line for a great snow....however, we may not know it until it happens.

I don't recall the models doing a GOOD job several winters. And of all models...the NAM got one RIGHT (although it's call was made really late in the game!)