Forecast and Analysis

Regional Migration Forecast: 5-12 September 2014

Andrew Farnsworth The Cornell Lab Sep 05, 2014

Continental Summary

Mid to late week favorable conditions will bring light to moderate movements to many portions of the West, while frontal passages bring an early and late week pulse of moderate to heavy movements through the East. Species on the move this week will include Osprey, Sharp-shinned Hawk, Franklin’s and Ring-billed Gulls, Philadelphia and Warbling Vireos, Veery, Swainson’s Thrush, Ruby-crowned Kinglet, Orange-crowned, Tennessee, Magnolia, Blackpoll, Black-throated Green, and Yellow-rumped Warblers, Savannah, Lincoln’s, White-crowned, and Vesper Sparrows, Green-tailed Towhee, and Rose-breasted Grosbeak

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.


Continuing the trends of previous weeks, the forecast period begins with scattered favorable conditions, mostly across more northerly portions of the region, that will facilitate scattered light to locally moderate movements where such conditions occur. Monday and Tuesday nights will see more intense movements in portions of the Pacific Northwest and in and to the east of the northern Rockies, where northerly flow or marginally northerly flow is forecast. By Wednesday and Thursday more extensive marginal and favorable conditions will allow for these movements to expand to their greatest extents of the period and for the movements to intensify to moderate or even locally heavy in some areas (particularly in the northern Rockies and eastern reaches of the region). Species on the move this week will include Lincoln’s Sparrow, American Pipit, White-crowned Sparrow, Say’s Phoebe, Ruby-crowned Kinglet, Golden-crowned Sparrow, Vesper Sparrow, Yellow-rumped Warbler, Fox Sparrow, American Wigeon, Green-tailed Towhee, Brewer’s Sparrow, Orange-crowned Warbler, Western Meadowlark, and Sabine’s Gull.

Great Plains

Moderate to locally heavy movements will begin the weekend, especially in the northern Plains, as marginal and favorable conditions facilitate exodus in those areas. However, conditions deteriorate for such movements to continue quickly over the course of the weekend, decreasing extents and intensities of movements to locally light to moderate for many areas through Monday night as southerly flow takes over and keeps many birds on the ground. A passing disturbance brings a new pulse of moderate to heavy movements to the Dakotas by Tuesday night, and the passage of this disturbance brings more intense moderate and heavy movements to most areas of the region of the end of the forecast period. Species on the move this week will include Lincoln’s Sparrow, Savannah Sparrow, Franklin’s Gull, Ruby-crowned Kinglet, Nashville Warbler, Western Grebe, Marsh Wren, Vesper Sparrow, and Osprey.

Upper Midwest and Northeast

Warm and moist conditions persist across much of the region to kick off the weekend, keeping movements light to locally moderate in most areas away from the western Great Lakes (where more favorable conditions spawn moderate to heavy flights). As the air masses over the western Great Lakes moves east, more favorable conditions and more intense moderate to heavy movements follow suit through the weekend. Although conditions never become highly favorable, moderate to heavy movements are likely to end the weekend in many areas. But these movements do not persist far into the work week, as southerly flow and warm and moist conditions return, keeping movements mostly light to locally moderate. Note that heavier movements may occur in the wake of local storm passages, similar to movements we discussed last year (see this story). By Wednesday night a frontal boundary brings a change to many areas in the Great Lakes and to the west of the Ohio River valley, where moderate to heavy movements will occur. By Thursday night favorable conditions associated with this frontal movement will bring more intense migration to more areas across the region, with the exception of the mid Atlantic and portions of southern New England where precipitation is forecast. Species on the move this week will include Palm Warbler, Blackpoll Warbler, Swainson’s Thrush, Gray-cheeked Thrush, Ruby-crowned Kinglet, Sharp-shinned Hawk, Northern Parula, Lincoln’s Sparrow, White-throated Sparrow, Black-throated Green Warbler, Philadelphia Vireo, Merlin, Rose-breasted Grosbeak, and Yellow-rumped Warbler.

Gulf Coast and Southeast

Unfavorable conditions that dominate the region begin to change over the weekend, and by Sunday night moderate to heavy movements are likely across much of the region away from the immediate Gulf Coast and southeastern coastal plains. This pulse of movements is short-lived, as much less favorable conditions build across the region over the remainder of the week. Light to locally moderate will be the norm during this time frame, with some isolated areas that experience more marginal or slightly favorable conditions and stay precipitation free experiencing more intense movements. Species on the move this week will include Swainson’s Thrush, Magnolia Warbler, Tennessee Warbler, Veery, Common Yellowthroat, Nashville Warbler, Rose-breasted Grosbeak, American Redstart, Chestnut-sided Warbler, Clay-colored Sparrow, Cape May Warbler, Scarlet Tanager, Black-throated Green Warbler, and Philadelphia Vireo.

Special September 11 Tribute in Light update for New York, NY

A frontal boundary is forecast to push through the greater New York metropolitan area on the evening of September 11, with major changes in wind direction (winds shifting to the west and then northwest), humidity (much drier), and temperature (cooler). As this occurs, birds will take flight as usual, and migration through the area will be moderate to heavy. Observers on the ground at the Tribute in Light in southern Manhattan will likely experience larger numbers of birds than in previous years, probably at times reaching thousands of birds.