Wednesday, May 10, 2006


Since I am working on our next weather-climate discussion for the ESRL/PSD MJO web site (link below), I will not have time to post a complete writing on this blog until hopefully sometime this weekend.

A very well defined convectively coupled signal, weakly projecting onto a MJO, is currently moving across the WH. The phase speed is ~8-10 m/s, and is roughly over the tropical Atlantic Ocean (where SSTs are ~1-2C above normal). Enhanced convection with this feature extends from the east Pacific ITCZ to central Africa. Twin upper tropospheric subtropical anticyclonic circulation anomalies linked to this forcing are present ~60W. Tied to the lingering effects of La-Nina, weakly coherent tropical convective forcing remains centered ~0/150E. Typhoon Chanchu has spun off from this convection. See:

Convection across the IO remains strongly suppressed. However, I do feel fairly confident the WH will come back around into the EH within the next 10 days. SSTs are ~1C above normal across the IO, and it is probable that the tropical convection will increase rapidly in this region with in the next 1-2 weeks. Another consolidation ~120E is possible roughly late week 2 into week 3 (keeping in mind the seasonal cycle).

GSDM Stage 3 best describes the current weather-climate situation. The current split-flow/large amplitude pattern across North America is going to persist ~5-7 days longer than I thought last weekend. This is partly due to feedbacks from the current high-latitude retrogression of the block that started in northern Europe about a couple of weeks ago. From next weekend into week 2, GSDM Stage 4 would be probable, meaning a continued retrogression the large amplitude ridge particularly from western Canada into the central Pacific. Like the CDC and Canadian ensembles hint at, that would allow the eastern Pacific trough to reach the Pacific Northwest coast during week 2 (with a STJ into the southwest USA). A more spring-like pattern may then return to the CONUS. In summary, what I advertised last weekend for a prediction looks to be delayed perhaps a week. Oh well, I guess I am struggling.

Ed Berry

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