Forecast and Analysis

Regional Migration Forecast: 29 August – 5 September 2014

Andrew Farnsworth The Cornell Lab Aug 29, 2014

Continental Summary

An early period patchwork of favorable and unfavorable conditions sees light to moderate movements scattered across the continent, primarily in the West, until a more organized and substantial end of the week frontal passage sees moderate to heavy movements in the northerly flow that follows. Species on the move this week will include Green-winged Teal, Wilson’s Phalarope, Hammond’s and Least Flycatchers, Nashville, Orange-crowned, Wilson’s, Magnolia, Chestnut-sided, Townsend’s, Black-throated Green, and Black-throated Blue Warblers, Clay-colored and White-crowned Sparrows, and Baltimore Oriole.

Arrows show wind speed and direction (arrow points in the direction to which wind is blowing) 100 m above ground level. Areas with southerly winds are colored red; northerly winds colored blue. Accumulated precipitation (in 6 hour intervals) is green, outlined by white. Broadly speaking, areas of the map in red will experience conditions that are favorable for migration, and areas where red and green (and red and blue) intersect and overlap may experience migrant concentrations and fallouts as migrants interact with precipitation.


Light to moderate movements will be scattered across the region this weekend, as a patchwork of favorable and unfavorable peppers the region. Sunday, Monday, and Tuesday nights will see the greatest extents of these movements, as northerly flow and clear skies will be most apparent on these evenings. But by the end of the forecast period, southerly flow takes hold in many areas, demising the intensity and extent of movements in all but the sparsest locales of the Pacific Northwest and Northern Rockies. Species on the move this week will include Lincoln’s Sparrow, Townsend’s Warbler, White-crowned Sparrow, Sharp-shinned Hawk, Hammond’s Flycatcher, Western Tanager, Yellow-rumped Warbler, Warbling Vireo, Orange-crowned Warbler, Clay-colored Sparrow, Green-tailed Towhee, Ruby-crowned Kinglet, and American Pipit.

Great Plains

Moderate to locally heavy movements that begin the weekend follow a frontal passage, but favorable conditions quickly give way to much less widespread movements in the days that follow. After the Friday night movements, southerly flow returns with a vengeance and largely remains in the picture for the remainder of the week. More favorable and marginal conditions do arrive locally across the region in the midst of this flow, bringing moderate and isolated heavy movements, particularly on Monday, Tuesday, and Wednesday evenings in the northern Plains states. Birders should watch the distribution of precipitation, especially on Sunday evening as birds may fly into unfavorable conditions and concentrate in areas where rain is falling. Species on the move this week will include Black-crowned Night-Heron, Green-winged Teal, Clay-colored Sparrow, Northern Shoveler, Barn Owl, Orange-crowned Warbler, Northern Harrier, Olive-sided Flycatcher, Nashville Warbler, Wilson’s Phalarope, and Swainson’s Hawk.

Upper Midwest and Northeast

A period of largely unfavorable conditions is in store for most of the region for this week, with southerly flow and warm and moist conditions keeping movements scattered and light. Some areas with more marginal or even locally favorable conditions, particularly in the Great Lakes, Ohio River valley, and New England, may experience higher densities. But it is not until Wednesday night in the Upper Midwest and Thursday night from the Great Lakes to the Atlantic that favorable conditions return and spawn widespread moderate to heavy movements. Note that early in the forecast period, offshore winds from the north and northeast may spawn some interesting near shore and onshore movements of shorebirds and passerines along the immediate coast – birders from Maine to DelMarVa should watch for coastal flights that may include an interesting component of typically over-Atlantic species. Species on the move this week will include Magnolia Warbler, Bay-breasted Warbler, Black-throated Green Warbler, Northern Parula, Nashville Warbler, Tennessee Warbler, Sharp-shinned Hawk, Black-throated Blue Warbler, American Redstart, Cape May Warbler, and Philadelphia Vireo.

Gulf Coast and Southeast

A week of unsettled weather that has more affinities to summer than fall will keep movements light and sparse during this forecast period. Some areas with more marginal and even locally favorable conditions may see light to moderate movements. However, the only moderate and possibly locally heavy movements will occur at the end of the period from the southern Appalachians west to the Mississippi River. Species on the move this week will include Wilson’s Warbler, Magnolia Warbler, Baltimore Oriole, Nashville Warbler, Tennessee Warbler, Veery, Chestnut-sided Warbler, Swainson’s Thrush, Least Flycatcher, Sharp-shinned Hawk, Blackburnian Warbler, Green-winged Teal, Cape May Warbler, and Blue-winged Warbler.