Saturday, August 6, 2011
12:52 A.M. (up late)
When storms come our way, I usually look at multiple weather models, because they all show different outcomes from the same set of present conditions. Sometimes these different outcomes are pretty similar, and other times, they are completely out of sync. When there is an especially tricky situation for the models to handle (such as a moderately-sized windstorm or a lowland snow event), events can change drastically from each iteration of the same model. This is especially common as forecast time increases, as the models become much less accurate due to the magnification of the approximations made after the input data goes in (I will talk about this some other time/search the blog for a post on it… I may have done it before).
However, when there are calm times like these, I use one model over all of the others because it is easy and it usually works. This is the “Extended WRF-GFS Model” from the UW, which can be found here: http://www.atmos.washington.edu/mm5rt/extendedgfsinit.html.
I’ve looked over this model for several days, and it has been pretty consistent in continuing the trend of cloudy mornings and bright afternoons. Some mornings are more cloudy than others; today only got to 66 degrees in downtown Seattle as the morning clouds proved too thick to burn off, but other mornings in the future may have little or no clouds at all. Regardless, I predict that over the next two weeks, we will see average temperatures with slightly below-normal precipitation. We’ve got that big blocking high over the Pacific that will shield us from any storms coming from our west.
Above is a shot of the current winds at the 300mb level of the atmosphere. As you can see, we are stuck in the doldrums between the northern and southern branches of the summer jet stream.