A few people have asked me why I haven’t written a new article about the tropics. You may have noticed that others have said “this is going to happen” or “that is going to happen.” =) I tend to focus on those events that I feel are likely to happen, or would be of interest to our users rather than just writing something with the intention of filling empty space! =)
I mentioned one of our HAMmodel products on Sunday, today I have been playing with a few more as well as researching into other HAMweather products that we have developed over the years, and future products we will be releasing to the general public, and some that will not be.
Of interest today is a product called “forecast snow depth.” Essentially what it means is that if snow were to fall in some area within a forecast cycle, how much snow would likely be left on the ground at the end of each interval within that forecast period?
As we discussed Sunday, NAM has been hinting at trace amounts of snow here and there, getting me pumped for the winter season. So today I thought I would show you what GFS is thinking along similar lines.
Keep in mind for those unfamiliar with computer model products, that just because a computer model thinks something is going to happen, does not make it so. However, with experience one learns to identify patterns over time that helps to explain what direction the atmosphere is moving, especially in identifying seasonal trends in space and time. Additionally, GFS is a very coarse resolution model, designed as such to fulfill its specific purpose.
Look closely at the scale on the bottom left of the graphics when you view them. I begin at 1/10 of an inch and move upwards with the intention of identifying generalized areas where snow depth is possible according to GFS. For example, notice the graphic below left (depending upon your browser, you may need to ‘click’ the image to view full size after opening. Image is 1024×768). This is from the 18z GFS run, for a forecast period out to 180 hours (7.5 days) from the time the model was initialized, valid for the time ending at 6z on Wednesday, October 8. 2008. Here GFS thinks that at that time in the Colorado Rockies somewhere in the neighborhood of 1.5″ of snow may be on the ground at higher elevations. Just thinking about that today, I’ve had Christmas songs playing inside my head: Silver Bells, White Christmas, the Charlie Brown Christmas song that I can never remember the name of =)
The second graphic at below right is an animation of the forecast snow depth product at 6 hour intervals out through 180 hours or 7.5 days. When viewing the graphic first keep in mind that I resize animations down to 800×600, and most importantly notice that snow depth will disappear in some areas as the animation loops. Such as in southern Michigan and upstate New York (October 3). Does this mean that it will or will not snow in those areas? =) That’s where the art of forecasting comes into play!
|Static Forecast Snow Depth Image Valid 6z 10/3/08||Forecast Snow Depth 180hr Animation|
Does GFS think snow will “stick around” in some areas of the Continental United States? =)