Thursday, October 04, 2007


Given travel and other obligations, it is not likely I will write another posting until hopefully Monday, 8 October. In the interim, there is no real news I could offer in regard to the current ocean-atmosphere coupling to La-Nina. Weak evidence suggests a recent mountain-frictional torque variation along with another northward propagation event of Eastern Hemisphere tropical convective forcing. In any case, diagnostic monitoring tools support the notions I discussed a week ago of tropical convective forcing redeveloping across the Indian Ocean closer to the equator with northwest Pacific tropical cyclones.

Hovmoller plots indicate a slow retrogression of extratropical circulation anomalies since ~ 1 September. I think there is a seasonal cycle component contributing to this in addition to the other processess persisting our GSDM Stage 1 base state. Again, this also supports my notion of a break from the barrage of western USA troughs. As it typical of October (in this situation enhanced), starting later week 1-week 2 eastern Pacific troughs-western USA ridges and troughs amplifying across the eastern states appear probable. Loosely this translates to warmer and dryer than climatology for much of the USA focusing on the Plains. Even with the westward shift the Pacific Northwest is probable to stay wet while Alaska remains north of the storm track.

Ed Berry

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