Sunday, May 23, 2010

More On Summer 2010 Outlook

John Diebolt (thanks John!) said: agree with the comments regarding the Climate Prediction Center's outlooks, the three-class system is misleading to the average person - They just look at the map and think well the darker the red, the warmer it will be, and those white areas mean normal temperatures, etc. Not to mention here in the SW we are seemingly permanently outlooked as above average to the casual observer. On a side note, I would like to offer kudos to Eric Pytlak for putting together his briefing. Monsoon season forecasting is terribly hard. Trying to refine so many variables into a local or regional-scale forecast would have been almost unheard of 10-15 years ago. Remember this time last year most indicators were pointing solidly to a wet and strong season? We wound up with a parade of low latitude closed lows well into early summer then a mid level high seemingly as jittery as a college kid on caffine- never in one spot for more than a day..and nearly always in the 'wrong' place for us. With the atmosphere/ocean circulations in such a rapid transition phase, anything could happen this year and I thought as a season opening salvo, Erik did a great job!
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First: let's review the details of last year's "Outlook" as per the web briefing hosted by U of A CLIMAS late last May:

Monsoon

The 2009 monsoon in the Southwest is forecast to be early and wet. During a Web briefing Thursday, May 21, scientists from The University of Arizona; the National Weather Service (NWS); Servicio Nacional Meteorológico, Mexico’s national weather service; and the National Center for Atmospheric Research emphasized the forecast applies to June and July but becomes more uncertain for August into September.

“The large-scale signal suggests the monsoon will arrive early and will be wet and strong,” said Chris Castro, an assistant professor of atmospheric sciences at the UA. The days leading up to the rains, he said, are likely to be very hot and dry. However, recent rainfall during the third week of May was not caused by the monsoon.

The NWS forecasts a 33 to 45 percent chance of above-average rainfall in June, but the forecast becomes increasingly uncertain later in the summer, said Erik Pytlak, a NWS meteorologist in Tucson. One reason is that forecasts indicate a rapid development of an El Niño event this summer into fall, which can weaken the easterly winds characteristic of the monsoon and bring drier weather to the Southwest.

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As John reported in his comment - these outlooks didn't verify well at all. The summer storms and rains weren't early and the first part of summer was not wet (at least in the Tucson and Phoenix regions - I'm not sure about far southeast Arizona (Art ?). Those who read my blog last summer know that I often referred to the dismal summer weather as the "nonsoon."

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My first question for anyone out there with an opinion: With the current, totally ambivalent, situation, should the LOCAL NWS be providing any climate forecast information, other than repeating what CPC has to say and referring questions to the "experts" at CPC?

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