Thursday, October 25, 2012

Strong weather ahead

This week's upcoming weather calls for an alert to all birders in the northeast US, Atlantic Canada & Ontario. We currently have a rather strong low pressure system in the Great Lakes region with an associated cold front draped south to Texas. Ahead of this front is a moderate-to-strong SSW flow in a straight line from Texas to SE Canada. Behind the front we see a sharp drop in temperatures with a moderate north wind.

courtesy of http://hint.fm/wind/


In late October (and through November), this is classic Cave Swallow weather. The birds are swept northeastward ahead of the front to the Great Lakes/Ontario region. If the front proceeds eastward with strong enough NW winds behind it, the birds will then redirect in a southeast heading, eventually reaching the east coast. It's quite predictable at this time of year.

Cave Swallows are the classic bird species associated with this weather, but really any migratory species from the central/western US is more likely to occur after such an event. For example, Ash-throated Flycatchers and Franklin's Gulls can also be linked to this pattern, though these guys are far less predictable than the swallows. It appears that this front will not clear the region in typical fashion, meaning that locally we won't be seeing NW winds in the immediate future, but the low and front are strong enough to displace birds so we should be on the lookout nonetheless.

This is only Part One of the story this week, and it's the one that is currently getting far less attention in the national headlines. Part Two is Hurricane Sandy, a Category 2 storm that has just passed north of Cuba and is about to move through the Bahamas. The big question is where this storm will be 3-5 days from now. Meteorologists presently have little confidence in the computer models given their variability, but within 24 hours they should have a better idea of what she's going to do. I'm going to hold off on any discussion until we know more, but stay tuned. At the worst, we may have another tropical cyclone on our hands. If not, we should at least see some strong winds behind it that could deposit some of those swallows and other western vagrants to our area.



 - Nick

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