Eastern Promises: Update 10 December 2012

Following last week’s post about the North Atlantic Oscillation (NAO) and the promise of European vagrants in North America, we thought it useful to note the current forecast from NWS Climate Prediction Center for the NAO index. The graphic below shows the forecast for the NAO index for the coming two weeks. Note, that there is a strong negative value forecast to continue through the coming two weeks, suggesting a period of easterly flow across the North Atlantic will occur over the coming 10-14 days.

Will this flow be sufficient to transport European species to North America? It is still too early to tell whether the easterly flow will be as strong and as extensive as that associated with the mid-to-late October event that brought the first wave of Northern Lapwings to North America. The synoptic map below shows strong easterly flow forecast for 14 December from just north of the United Kingdom across the North Atlantic to Greenland. Note, also, the southerly winds from Europe north into the North Sea. This flow does not reach the mainland of the continent, but it gets close; if the easterly flow extends farther west, conditions would likely be even better for displacing European vagrants. Nonetheless, given the small but exciting bounty from the October event, birders in Eastern Canada and the Northeastern US should be watchful, particularly in coastal locations, for oddities from across the pond beginning 10-14 December.

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