Forecast and Analysis

Regional Migration Forecast: 7-13 September 2013

Andrew Farnsworth The Cornell Lab Sep 06, 2013

Continental Summary:

A divided West sees light to moderate movements, as a complex East sees several primarily northern pulses of moderate to heavy movements. Birds on the move this week will include Sharp-shinned Hawk, Eastern Kingbird, Barn Swallow, Ruby-crowned Kinglet, Swainson’s Thrush, Palm and Blackpoll Warblers, and White-throated and Lincoln’s Sparrows.


The weekend sees mostly favorable conditions for light to moderate movements to the West to the Rockies, with less favorable conditions farther East. This pattern changes during the early part of the week, when the distinction is less East to West and more North to South, with more favorable conditions in the Pacific Northwest, Great Basin, and northern Rockies prevailing through Wednesday night. Conditions become less favorable across the region to end the period, with light movements being the norm on Thursday and Friday. Birds on the move this week will include American Wigeon, Say’s Phoebe, Ruby-crowned Kinglet, American Pipit, Yellow-rumped Warbler, and Lincoln’s, Vesper, and White-crowned Sparrows.

Great Plains

Marginal conditions prevail this weekend, with areas closer to the Canadian border experiencing mostly light to moderate movements to begin the weekend and areas farther south experiencing primarily scattered light movements. Some areas of the northern Plains may see localized heavy movements on Saturday night, particularly in the Dakotas as a fast moving high passes to the North and East of the region. Tuesday night sees a return of favorable conditions to the northern Plains, extending to the South and East on Wednesday, facilitating moderate to heavy movements. As a high pressure center moves East to end the week, marginal conditions return and movements will be mostly light, locally moderate where winds are more calm in eastern and northern portions of the region. Birds on the move this week will include Double-crested Cormorant, American White Pelican, Sharp-shinned Hawk, Franklin’s Gull, Eastern Kingbird, Ruby-crowned Kinglet, Marsh Wren, Swainson’s Thrush, Yellow-rumped Warbler, Chestnut-collared Longspur, and Lincoln’s Sparrow.

Upper Midwest and Northeast

The weekend begins with mostly marginal and unfavorable conditions across the region, with light to moderate movements being the norm in most places. However, the Appalachians may be more active, seeing moderate to locally heavy movements in more favorable conditions of calm and even light northerly flow. Sunday night brings a change to the region, as favorable conditions ahead of the high pressure center building over the Great Lakes spawn moderate to heavy movements across the region. These movements will also include good morning flights on Monday morning in New York and New England, particularly in coastal areas. An approaching front brings less favorable conditions for the beginning of the work week, but clearing comes quickly by Wednesday to the Mississippi River valley, Thursday to the Appalachians, and Friday to the coast. As this clearing trend moves East, moderate to heavy movements will follow. Skywatchers should also track these conditions, because hawk watching will be good as this air mass moves East. Birds on the move this week will include Sharp-shinned Hawk, Ruby-crowned Kinglet, Swainson’s and Gray-cheeked Thrushes, American Redstart, Northern Parula, Ovenbird, Palm, Blackpoll, and Black-throated Green Warblers, and Lincoln’s and White-throated Sparrows.

Gulf Coast and Southeast

Light to moderate movements will prevail for the weekend in primarily marginal and unfavorable conditions, with the possible exception of some areas of the southern Appalachians that may experience locally moderate to heavy movements. Conditions are forecast to deteriorate over the course of the forecast period, and migration will be shut down in many areas where precipitation falls. However, given the time of year, when rain is not falling, birds will be moving, so light to moderate movements will occur in many places if precipitation does not occur. Not until the end of the period, on 13 September, does the air mass presiding over the region change markedly, bringing northerly and northeasterly flow and more extensive moderate to heavy movements away from the coastal plain. Birds on the move this week will include Black Tern, Barn Swallow, Gray Catbird, Veery, American Redstart, Common Yellowthroat, and Nashville, Tennessee, Palm, Magnolia, and Chestnut-sided Warblers.