Sunday, November 20, 2011

+AMO/-PDO Provides Support To Major Trough Potential In Last Days of Nov.

Effects of PDO

Table 1: summary of Pacific and North American climate anomalies associated with extreme phases of the PDO.
climate anomalies
Warm Phase PDO
Cool Phase PDO
Ocean surface temperatures in the northeastern and tropical Pacific
Above average
Below average
October-March northwestern North American air temperatures
Above average
Below average
October-March Southeastern US air temperatures
Below average
Above average
October-March southern US/Northern Mexico precipitation
Above average
Below average
October-March Northwestern North America and Great Lakes precipitation
Below average
Above average
Northwestern North American spring time snow pack and water year (October-September) stream flow
Below average
Above average
Winter and spring time flood risk in the Pacific Northwest
Below average
Above average


Joe Bastardi, former Chief Long Range Meteorologist at Accuweather, has put up a message indicating that a +AMO/-PDO would help the potential for the theory of a major trough to hit the East/North US going into the last few days of November. You can see the differences between a warm PDO and negative PDO in the columns above, thanks to the University of Washington.
We are currently in a Cold PDO phase and a warm AMO phase. These indices change on a multidecadal basis- every couple decades. Since the mid 1990s, the AMO has been on a mainly positive streak. However, it is less positive than last year. During the warm phase of the AMO, temperatures across North America are above average, as shown by this map below thanks to Intellicast.
Since we are in a less positive phase than last year, it is possible that global temperatures may be slightly cooled from last year, in addition to low sunspots.
We will have more information on the trough as we come closer to the date.

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