(Senior Storm Chaser)
Tue Dec 06 2005 11:00 AM
Re: graycast

More on the Graycast (more like 'overcast' it's so gloom and doom!); this is from Jeff Master's Wunderground blog this morning, and I found this summary of the factors taken into account in the forecast very helpful (for newbies like me):

"The CSU team uses observations of monthly average atmospheric winds and pressures over six specific regions of the globe taken this Fall to determine whether favorable or unfavorable conditions will exist for the 2006 hurricane season. All six of these "predictors" are favorable for an active 2006 hurricane season. A condensed summary:

"1) El Niņo, which acts to suppress Atlantic hurricane activity, is not expected to be active during the 2006 hurricane season. It is more likely that neutral or even La Niņa conditions will develop, which are favorable for Atlantic hurricane activity.

"2) The stratospheric quasi-biennial oscillation (QBO), an oscillation in the stratosphere that creates alternating westerly and easterly winds there, is expected to be in it west phase during the hurricane season of 2006. The west phase of the QBO has been shown to provide favorable conditions for development of tropical cyclones in the deep tropics.

"3) The observed pressure and wind patterns over the North Atlantic will allow stronger than normal southerly winds to keep sea surface temperatures over the entire North Atlantic well above normal during 2006. Sea surface temperatures during 2005 were the highest measured since at least 1950, and helped fuel 2005's record-breaking intense hurricanes. Sea surface temperatures during the 2006 hurricane season may be just as warm.

"4) Perhaps most importantly, observed wind and pressure patterns this Fall indicate that upper-level winds in the upper atmosphere (200 mb) will blow from the east during the hurricane season of 2006, like they did during 2005. This results in low wind shear over hurricane formation regions of the tropical Atlantic. Low wind shear is the key ingredient needed for tropical storm formation and intensification.

Jeff Masters"

margie, for large excerpts like this you should just put a link... unless you have a bunch of specific comments related to the text. -HF

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