Wednesday, November 24, 2010

Winter 2010-11 Outlook Part 2 - What to expect

The base state of the atmosphere is expected to feature, a NW US trough which expands to the Great Lakes, and a storm track which is primarily west of the Appalachians toward the Greak Lakes.   This leaves the SE US in what is most often a mild and dry sector.  This prognostication is based on the Ocean temperature anomalies:
Ocean Sea Surface Temperature Anomalies
  1. La Nina - Cold water along the equator encourages buildup of high pressure and a subsequent slowing of Global AAM along the equator.  As a result warm high pressure is favored southeast of mountain ranges and continents.
  2. East Pacific Oscillation Zone - Positive state is favored. High Pressure NE of Hawaii favors a trough and subsequent stormy weather in the NW US.
  3. Cool Ocean near SE US - Favors stable surface high pressure.
  4. Warm near Darwin AU - Darwin downpours are great for those who want to play golf and other outdoor sports near the eastern seaboard and south of the Mason-Dixon line.  This can change quickly!
  5. The North Atlantic Oscillation Zone - The ocean favors a positive base state (mild and dry SE US) BUT there are influences which are in play to cause potential trouble. 
      Therefore we are in a situation where much of a winter will be warmer than average and dry.

Now for the interesting part...
     Winter 2010-11 will be remembered for its events not for being consistently miserable like last year.  I am deeply concerned that January's "Bear Market Rally" when the North Australia rainy season comes to an end has tremendous potential for bring destructive weather to our region.  La Nina's are well known for volatility because of the terrible cold which is often dammed up north of the jet stream.  There comes a time that imbalances must be satisfied.  The legendary snowstorm of January 2000 is an extreme version of a breakout event.  In other seasons like this one severe thunderstorms and tornadoes strike in January when they are least expected.  January 2008 featured a 4 day historic Tornadic outbreak.  The 1996 January Blizzard paralyzed the whole eastern seaboard.

     Unlike 2007-08 when I predicted very little winter at all the hurricane paths, evidence that La Nina has already hit bottom, volcanic activity, a subtropical jet stream (unusual for this weather pattern), and continued low solar all seem to indicate that this winter for Central VA and NC is one with a great deal of potential to be remembered for its misbehavior for a long time.

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