500 mb Heights
The following image displays the last four 12Z runs of March 24, 25, 26, and 27. The last four 12Z runs have been nearly consistent through the last four days of GFS model runs. The model run from today is indicated by the light blue color and the earliest model run from 12Z march 24 was the darker blue color. The earliest model run wanted to close the 500 mb height contour over the northwestern portion the United States for 12Z 27 March 2012. All models picked up on a ridge-trough pattern across the United states and the observations from 12Z 27 March 2012 verified.