What kind of future signals are these teleconnectors pointing to at present?
First, let me share with you today's graphs of the NAO, AO, and the PNA respectively.
North Atlantic Oscillation (NAO)
Please enlarge the graph above, as of today, December 9, the trend for the NAO going forward is positive, with some vascillation between neutral and positive. Although the 7-day forecast confidence level remains quite high, afterward, confidence values decrease. In fact, the 10-day forecast drops below 50 yet continues to show mostly a positive trend.
Not good for big snows around here unless the signals show something different in the coming days.
Next, the Arctic Oscillation (AO)
Unfortunately, the AO is forecast to remain positive, and the forecast values going forward are pretty confident for the next 10 days with some expected fluctuations between positive and neutral.
Last, the Pacific North American (PNA) pattern...
After a brief dip, the PNA is expected to turn neutral, perhaps slightly positive. PNA values that are negative allow for colder air to stay out west. However, this time, PNA values could go slightly positive in the days ahead. This would warm up the west and provide the midwest some cold air dropping in from Canada. However, as the NAO should remain positive, any cold air should not last too long.
This certainly sounds frustrating, as my winter forecast for 2011/2012 indicates a turn to a long-lasting colder air pattern, especially by the end of the month. Remember, though, it's still early. I'm still expecting the effects of La Nina to begin intensifying here by the end of the month. But, we do need the NAO to begin its trend toward negative, if we are going to see any threat of a big snow system.
Hopefully, in the days ahead, the trend will become our friend and begin pointing toward a colder, more typical wintry pattern for late December.
MS
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