University of Washington Models, and Stormy Early Next Week?

Friday, September 30, 2011
6:06 P.M.

Now that I am an official UW student, I figure I might as well advertise the super-ultra-awesome mesoscale modes at the University of Washington Department of Atmospheric Sciences Website.

There are two main models that the University of Washington runs. These are the NAM (North American Mesoscale) and GFS (Global Forecast System). These are the most common models used by NOAA. What makes these models different is that they have extremely high resolution.

But what is resolution? I don’t completely understand it… I’ve read Cliff’s blog post on it but I still don’t quite understand it. From what I’ve read, it seems to mean the difference in space between the points on a three-dimensional grid. There are forecasting models done in 3-dimensions, but something I have seen more often is a 2-dimensional grid that has no vertical component. Even though you would generally use x and y, it looks as though based on the picture below, you would use x and z and omit y, because y is the height component, while x and z are situated horizontally.

Again, you shouldn’t take my word for this, I could be completely wrong, but hopefully I am not.

Three-dimensional resolution – Cliff Mass Weather Blog, “Resolution, ” 9/14/11
Cliff Mass did a post on this, and used this exact picture. I will try to steer this blog post away from being a copy of his, but he talked directly about resolution, and that is what makes the UW models special. I don’t want to get kicked out of college for plaigarism. If anybody reads this, and I am not citing enough credit, let me know. If this screws me over for college, I might as well join Delta House (John Belushi, anyone?). 
But in all seriousness, I’ll show you the two basic models, plus different levels of resolution. Both the NAM and the GFS here use different mesoscale models to provide resolution. The NAM uses the MM5 (Penn. State/NCAR mesoscale model) and the GFS uses the WRF (Weather Research and Forecasting model).
The GFS, which is generally more accurate, has 36, 12, 4, and 4/3 km resolution runs, and the NAM has 36 and 12 km ones.
Let’s take a look at the GFS!!!
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 36km 00z WRF-GFS 2-meter temp
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 12km 00z WRF-GFS 2-meter temp
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 4km 00z WRF-GFS 2-meter temp
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 4/3km 00z WRF-GFS 2-meter temp
All of these pictures are from the same time frame, which has already passed, but you can see the difference in resolution! Sorry about the 36km GFS, they only had that size (at least that I could find)
Now the NAM…
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 36km 00z MM5-NAM 2-meter temp
Valid 02:00 pm PDT Fri, 30 Sep 2011 – 21hr Fcst – UW 36km 00z MM5-NAM 2-meter temp
You get the idea. More resolution = more accurate forecasts. This will be especially useful for convergence zone events!!!
Now, let’s look at next week… I’ll have more details as it approaches, as the models aren’t in perfect agreement, but we will see some moderate systems and there is a chance we could see a strong one. I wish I could give you more information, but doing so could be misleading. However, there could be strong winds on Tuesday as a surface low moves to our north. It looks to be weakening as it moves ashore, but if that changes, we could get pretty blustery.
Thanks for reading, I hope you learned something today!

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