Forecast and Analysis

Regional Migration Forecast: 12-19 September 2014

Andrew Farnsworth The Cornell Lab Sep 12, 2014

Continental Summary

Pulses of more provincial movements that begin the weekend contrast the widespread movements that will end the period in the West, while the opposite pattern of movements occurs in the East. Species on the move this week will include American Wigeon, Eared Grebe, Osprey, Sharp-shinned and Broad-winged Hawks, Say’s Phoebe, Swainson’s and Gray-cheeked Thrushes, Ruby-crowned and Golden-crowned Kinglets, American Redstart, Black-throate Blue, Yellow-rumped, Tennessee, Magnolia, and Palm Warblers, White-throated, White-crowned, and Golden-crowned Sparrows, 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.


The weekend begins with light to moderate flights in the Pacific Northwest and norther Rockies as well as scattered portions of the Desert Southwest and California. This pattern holds for most of the weekend but begins to collapse by early in the work week as southerly flow returns more marginal conditions to most areas. Conditions in the Rockies remain favorable to marginal for the light to moderate movements to continue during this period, but by Wednesday southerly flow overspreads much of the region and puts a damper on movements in most locations. A substantive change to this widespread unfavorable flow follows, as a disturbance and precipitation spawned from the southerly flow moves out of the region, allows more favorable conditions to return, and facilitates light to moderate and even locally heavy movements to end the period. Species on the move this week will include Golden-crowned Sparrow, White-crowned Sparrow, Fox Sparrow, Lincoln’s Sparrow, Ruby-crowned Kinglet, Yellow-rumped Warbler, Say’s Phoebe, American Wigeon, Eared Grebe, American Pipit, Merlin, and Hermit Thrush.

Great Plains

A pulse of moderate to heavy movements in the southern Plains contrasts much lighter movements farther north to begin the weekend. This pattern flips over the course of the weekend, as southerly flow spreads and moves east across the region. The work week sees movements generally diminish in extent and intensity as more unsettled conditions move in. These unsettled conditions culminate at the end of the week with the arrival of a substantial frontal boundary. Species on the move this week will include Ruby-crowned Kinglet, White-crowned Sparrow, Harris’s Sparrow, Lincoln’s Sparrow, Yellow-rumped Warbler, Franklin’s Gull, White-throated Sparrow, Dark-eyed Junco, Orange-crowned Warbler, Pied-billed Grebe, Vesper Sparrow, Swamp Sparrow, and Osprey.

Upper Midwest and Northeast

Widespread moderate to heavy movements, particularly east of the Appalachians, will kickoff the weekend. Some of these movements may reach the rare very heavy condition. Birders interested in flight calls should consider breaking out the microphones and spending time outside on Friday night. Most of the region continues to experience moderate to heavy movements on Saturday, away from New England where a passing disturbance shuts down migrants and the Upper Midwest where southerly flow arrives. The following days see a patchwork of moderate to heavy movements in different portions of the region where more favorable northerly flow persists, until Wednesday night when more extensive and intense movements become widespread in most areas. The end of the week see most of the favorable conditions, and the moderate to heavy movements associated with them, occurring primarily east of the Ohio River valley and north of DelMarVa. Species on the move this week will include Ruby-crowned Kinglet, White-throated Sparrow, Lincoln’s Sparrow, Yellow-rumped Warbler, Palm Warbler, Sharp-shinned Hawk, Broad-winged Hawk, Golden-crowned Kinglet, Blue-headed Vireo, Swamp Sparrow, Yellow-bellied Sapsucker ,Winter Wren, American Pipit ,White-crowned Sparrow, a suite of warblers, and Brown Creeper.

Gulf Coast and Southeast

Moderate to heavy movements begin the weekend in many areas of the region away from the coast, gradually shrinking in extent over the course of the weekend as more southerly flow returns to overpower its cooler and drier northerly flow. By early in the week, precipitation spreads, more unsettled conditions become more widespread across the region, and migration will be greatly diminished. And just as another blast of marginal and favorable northerly flow on Wednesday and Thursday will return moderate to heavy movements to inland portions of the Mississippi River valley and southern Appalachians, a more organized suite of disturbances with more precipitation and southerly winds takes hold to end the period and shuts down most movements. Species on the move this week will include Rose-breasted Grosbeak, Palm Warbler, Swainson’s Thrush, Merlin, Black-throated Blue Warbler, Magnolia Warbler, Ruby-crowned Kinglet, Common Yellowthroat, Gray-cheeked Thrush, Sharp-shinned Hawk, Ovenbird, Veery, American Redstart, Philadelphia Vireo, and Tennessee Warbler.