Sunday, April 22, 2012

Bird Migration Forecast

Cornell's eBird website has released their bird migration forecasts for this week. I've excerpted the sections relevant to folks here in the northeast, but you can read the entire forecast here.

BirdCast Migration Forecast: 20 - 26 April 2012

Areas of the western US lacking precipitation should experience widespread light to moderate migration early in the forecast period, but an increasing threat of precipitation later in the week may shut down movements in many places. The Great Plains begin the period with largely unfavorable conditions for bird movement, but by midweek southerly flow returns and widespread moderate movements should occur. A frontal passage will make for poor conditions across the Upper Midwest, but favorable conditions for moderate movements in the Northeast to begin the period. Better conditions for more widespread moderate movements should develop around midweek. The Gulf Coast and Southeast begin the period with the passage of a front that could spawn some coastal fallouts in the western Gulf region; but this front will shut down the trans-Gulf migration system until midweek, when a return to more widespread moderate movements begins.

Daily forecast maps are available here.

Black-throated Gray Warbler
The western U.S. should see a good movement of Black-throated Gray Warblers this week. Expect arrivals across the breeding range from Colorado to Washington, Oregon and into British Columbia. Migrants are likely to be found with flocks of Yellow-rumped Warblers, kinglets and other landbirds. Late April and the first couple days of May are also excellent times to watch for this species in the Great Lakes region, where very rare. There are several records that stretch from New York to Ohio and Wisconsin for this time period. There is even a record from St. Catherine's Island, Georgia. Take a look at the April and May map here and zoom into your region of interest.

Upper Midwest and Northeast
Although most of the Upper Midwest begins the period with unfavorable northerly winds and precipitation, many areas of the Northeast will see favorable southerly winds that facilitate widespread moderate movements. Some of these may be locally heavy. Birders in the eastern Great Lakes, far northern portions of the region, and Appalachian areas should be aware of the potential for fallouts in areas where precipitation meets bird movements. As the front passes, largely unfavorable conditions will persist across the region through the beginning of the week; some areas in the western Great Lakes may see widely scattered light to moderate movements during this time, as some clear periods with calm or favorable winds may occur. By Wednesday, with high pressure centered over the Central Appalachians, western portions of the region should see more extensive moderate movements, some of which may be locally heavy. By the end of the forecast period, many areas away from the immediate coast and northern New England should see widespread moderate movements, including scattered heavy movements; the immediate coast and adjacent areas are still forecast to have westerly and northerly winds, but even in these primarily unfavorable winds, light to moderate migration may occur and concentrate birds along the coast. Birders in the western Great Lakes should watch precipitation associated with low pressure to the north on Thursday, as it may spawn local fallouts.

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