Forecast and Analysis

Regional Migration Forecast: 30 March – 5 April 2013

Andrew Farnsworth The Cornell Lab Mar 29, 2013

Continental Summary:

This week’s migration forecast features an opening of some flood gates for migrant arrivals in the Eastern and Central US, while new arrivals continue to move across many areas of the West.


Mostly favorable conditions bring a forecast for light to moderate movements and continuing spring arrivals for most areas of the region.

Many areas of the West begin the weekend with mostly favorable conditions for light to moderate movements that continue through the weekend. Similar conditions are forecast to prevail in many areas for most of the week, suggesting a week of widespread arrivals for many species in many areas. High pressure to the East, however, may create a frontal boundary that stalls over the northern Rockies, slowing the onset of arrivals in those areas. On the move should be, among others, Turkey Vultures and Ospreys, Ash-throated Flycatcher, more northbound swallows, Yellow Warbler, Lazuli Bunting, and Black-headed Grosbeak.

Great Plains

Favorable conditions will occur for light to moderate movements in many areas, particularly later in the forecast period.

Light to moderate movements begin the weekend as a disturbance moves across the region. In its wake comes another large high pressure center, which will diminish movements to locally light and moderate in most areas. By the beginning of the week, this center slowly moves East, and by Tuesday night creates favorable conditions for more widespread light and moderate movements in many areas. This pattern will continue through the forecast period, although two disturbances in the northern Plains states will likely diminish the numbers of arrivals that are occurring farther to the South. Continued passage of and increases in Turkey Vulture, Red-tailed Hawk, and Osprey, Long-billed Curlew and other shorebirds, more swallows, House Wren, and Northern Parula will be apparent.

Upper Midwest and Northeast

Unfavorable conditions begin the period, but the potential for a floodgate to open for new arrivals comes by Sunday-Monday and again by Wednesday-Thursday.

High pressure continues to dominate, with northerly flow continuing to keep migrant arrivals to only a trickle in most places. As the high moves East by Sunday, more favorable conditions overspread the region and more widespread light to moderate movements occur. There should be a substantial pulse of migration in many areas, as these conditions will be the first even close to marginal conditions for movements in the past days. Areas in the Mississippi River Valley and western Great Lakes should watch for fallout conditions, particularly waterfowl and swallows. After this high moves East, a brief night or two of less favorable conditions will prevail, only to be followed by increasingly favorable conditions for light and moderate movements by the middle of the week. Another good pulse of arrival will occur between midweek and the end of the forecast period, particularly from coastal New England south through the Mid-Atlantic states. Birds on the move will include, among others, Snowy Egret, more early shorebirds like Pectoral Sandpiper, Forster’s Tern, continued swallow arrivals, Blue-headed Vireo, Palm Warbler, and Louisiana Waterthrush.

Gulf Coast and Southeast

Light to moderate movements occur in many areas, though an approaching and then passing cold front may spawn fallout conditions in a number of coastal areas by midweek.

High pressure dominates to begin the period, but light winds will allow light to moderate movements to be widespread in many areas. Although an approaching cold front may shut down some movements in the northern portions of Gulf states, birds should continue moving closer to the coast and in Texas and Florida. By Tuesday, however, this front pushes into the Gulf of Mexico, shutting down trans-Gulf flights and diminishing most overland movements to light levels. The degree to which this front pushes into the Gulf and its exact timing for doing so warrants close observation, as the potential for fallouts in coastal locations exists as winds shift to the north. Birders should be watchful beginning on Tuesday, focusing on coastal stopover habitat and migrant traps. As the front stalls over the northern Gulf of Mexico to end the period, light to moderate movements will occur overland in light winds, while small input of trans-Gulf migrants may add to some concentrations of birds already present in coastal stopover habitats. Birds on the move this week include Green Heron, more shorebird arrivals, and numerous passerines including Red-eyed Vireo, Scarlet and Summer Tanagers, Indigo Bunting, Rose-breasted Grosbeak, Yellow-breasted Chat and Orchard Oriole.