Forecast and Analysis

Regional Migration Forecast: 17-23 August 2013

Andrew Farnsworth The Cornell Lab Aug 16, 2013

Continental Summary

The West will experience light to moderate movements early and late in the forecast period, and locally midweek where scattered precipitation is not falling, as the East experiences a mostly marginal and unfavorable weather week that will allow mostly light and locally moderate movements interspersed among increasingly prevalent showers and precipitation as the forecast period ends. Birds on the move this week will include Blue-winged and Green-winged Teal, Baird’s and Stilt Sandpipers, Olive-sided Flycatcher, Barn Swallow, and Yellow Warbler.


Although some scattered precipitation is forecast in portions of the region, most areas will experience light to moderate movements. This may be particularly true in the coastal Plain and near coastal ranges from Washington south through California. This pattern continues though to the middle of the week, though the increasing threat of precipitation means birds will be grounded in increasingly more areas where it falls. However, by the end of the forecast period, favorable conditions return to all but the mountainous eastern and far northwestern reaches facilitating moderate movements along the Pacific Coast and inland valleys south of Washington. Birds on the move this week will include Green-winged Teal, Northern Shoveler, Northern Pintail, Western, Baird’s, Stilt, Pectoral, and Solitary Sandpipers, Belted Kingfisher, Nashville, Orange-crowned, Yellow, Townsend’s, Wilson’s, and MacGillivray’s Warblers, and Lazuli Bunting.

Great Plains

Although reasonably clear skies are likely for the weekend in many areas, unfavorable or at best marginally favorable winds are forecast and mostly light to locally moderate movements will occur. These may be heavier if winds are lighter than forecast, particularly along the border states. This pattern continues into the week, and, compounded with an increasing threat of scattered precipitation, will keep migration on the lighter side for the remainder of the period. Birds on the move this week will include Least Flycatcher, Red-eyed Vireo, Gray Catbird, Black-and-white and Wilson’s Warblers, American Redstart, Baltimore Oriole, and Vesper Sparrow.

Upper Midwest and Northeast

Unfavorable and marginal conditions for migration are the norm for this week, with scattered precipitation and largely unfavorable winds ruling the roost. When and where precipitation is not falling, light movements will occur. Some widely scattered areas may see moderate movements if winds are calm and skies are clear. Most interesting is the forecast for the end of the period, when more favorable conditions are possible. On Thursday and Friday nights, birders in the Northeastern US and eastern Great Lakes should watch for the possibility of higher intensity movements in marginally or even favorable northerly or northeasterly flow. This may occur in a very narrow geographic zone from Pennsylvania north through New England. Birds on the move this week will include Red-necked Grebe, Green-winged Teal, Blue-winged Teal, Baird’s and Stilt Sandpipers, Common Nighthawk, Red-eyed Vireo, Tennessee, Magnolia, Black-throated Green, Chestnut-sided, Blackburnian, and Canada Warblers.

Gulf Coast and Southeast

The portions of the region West of the Mississippi will be the most likely to experience moderate to locally heavy movements to begin the weekend and possibly in the early part of the week, while the remainder of the region is forecast to experience rain and mostly migration shut downs. As the week continues, precipitation lingers and will be scattered across many parts of the region, shutting down most movements. When and where skies are clear, light to locally moderate movements will occur. However, these will be increasingly few and far between as the forecast period comes to an end. Birds on the move this week will include Blue-winged Teal, Olive-sided Flycatcher, Red-eyed Vireo, Barn Swallow, Ovenbird, Worm-eating and Yellow Warblers, and American Redstart.