500 hPa Height Pattern Composite

Here is a composite of the 500 hPa height pattern associated with strong events. Though we were questioning whether the 500 hPa height anomalies were showing weakening of the monsoonal ridge or an actual trough, it appears quite clear from the actual height patterns that the anomaly feature is indeed associated with a strong trough moving in from the Pacific.

Ridging, though relatively weak in nature, does appear to be in place slightly east of the Four Corners (i.e., Four Corners' High) on Day -4 and -3 to the event. At this time we are already seeing signs of a deepening trough off Northern California. As we progress closer to the event day the trough deepens dramatically, nearly explosively, and progrades into regions where it could potentially affect the characteristics and development of the NAM system. The actual height patterns and the anomaly fields display a strong spatial relationship to one another, and thus, I feel confident say that the anomalies we are seeing are associated with a trough feature.

There are still quite a few questions regarding the origin of this trough feature though. More on that to come soon.

Same Bat-channel...Same Bat-Time.

-jamie