Forecast and Analysis

Regional Migration Forecast: 9-16 May 2014

Andrew Farnsworth The Cornell Lab May 09, 2014

Continental Summary

A patchwork of conditions in the West brings mostly scattered light to moderate movements over the forecast period, while a wild week of moderate to heavy movements and the potential for fallouts scattered among precipitation and severe weather comes to the East. Species on the move this week will include Ruddy Turnstone, Stilt and White-rumped Sandpipers, Yellow-billed Cuckoo, Common Nighthawk, Eastern and Western Wood-Pewees, Willow and Alder Flycatchers, Red-eyed Vireo, many warblers, Chipping, White-throated, and White-crowned Sparrows, Rose-breasted and Blue Grosbeaks, and Bobolink.

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.


A patchwork of conditions kicks off the weekend, with largely unfavorable weather for movements in the Pacific Northwest and favorable conditions for moderate movements in the Desert Southwest and eastern Rockies. Over the weekend, however, unfavorable conditions overspread the region, limiting movements increasingly to only portions of the Desert Southwest by Sunday night. These conditions continue for much of the week, with only isolated areas of favorable conditions scattered locally across the region (where light to moderate movements will occur). Wednesday night sees favorable conditions expand in more areas of the Desert Southwest and eastern Rockies. As the week draws to an end, favorable conditions again are scattered widely, and an increasing number of areas will experience light to moderate movements, in particular California, the Colorado and Gila River valleys, portions of the northern Rockies. Species on the move this week will include Solitary Sandpiper, Greater and Lesser Yellowlegs, Dunlin, Least Sandpiper, Olive-sided Flycatcher, Western Wood-Pewee, Willow Flycatcher, Eastern Kingbird, Veery, Swainson’s Thrush, Gray Catbird, Cedar Waxwing, Yellow Warbler, Western Tanager, Blue Grosbeak, Indigo Bunting, Bobolink, and Orchard Oriole.

Great Plains

A weekend of variable, and sometimes dangerous, conditions brings moderate to heavy movements to some areas, while other areas get shut down by precipitation. Birders should watch carefully where favorable conditions carrying migrants and unfavorable conditions interact. However, birders should also exercise extreme caution, as severe weather, including dangerous tornadic storms, are forecast during the weekend. As low pressure moves out of the region by Monday, Monday night sees unfavorable conditions overspread the region; despite these, light to moderate movements may occur locally in more marginal conditions, given the time of year, despite the northerly flow. Favorable conditions return by Wednesday night, bringing a new round of moderate to heavy movements to the central and southern Plains, but these movements stay localized to this part of the region as the northern Plains continue to see unfavorable conditions and sparse light to locally moderate movements. Species on the move this week will include Ruddy Turnstone, Stilt and White-rumped Sandpipers, Red-necked Phalarope, Least and Black Terns, Yellow-billed Cuckoo, Eastern Wood-Pewee, Alder Flycatcher, Mourning Warbler, American Redstart, Magnolia Warbler, Lark Bunting, Bobolink, and Orchard Oriole.

Upper Midwest and Northeast

Southerly flow coupled with widespread threat of precipitation will make for an forecast period across much of the region. Moderate to heavy movements are likely in many areas, but precipitation scattered throughout the region may create local concentrations or shut down movements depending on its exact distribution. Birders across the region should watch carefully where migration and precipitation meet, because an interesting mix of species’ concentrations or fallouts may occur. This includes passerine concentrations, but also migrating waterbird on inland bodies of water (including, perhaps, rare migrants like Red Phalarope and Arctic Tern, although timing is still a bit early for those). Note also that by the end of the forecast period, the trans-Atlantic flow of easterlies that has brought numerous European vagrant shorebirds to the Canadian maritimes may bring some surprises to New England – BirdCast will highlight this discussion further in an upcoming post. Species on the move this week will include Semipalmated Plover, Ruddy Turnstone, Semipalmated Sandpiper, Common Nighthawk, Eastern Wood-Pewee, Willow Flycatcher, Red-eyed Vireo, Cedar Waxwing, Mourning Warbler, American Redstart, Magnolia, Bay-breasted, Blackpoll, Canada, and Wilson’s Warblers, and Chipping, White-throated, and White-crowned Sparrows.

Gulf Coast and Southeast

Scattered precipitation makes for interesting possibilities in the otherwise favorable conditions forecast for the weekend. Moderate to heavy movements will occur where precipitation does not fall, but many areas may experience concentrations or fallout conditions where migrants meet rain. This includes trans-Gulf migrants and circus-Gulf migrants. By Monday night, a strong frontal boundary moves into Texas, shutting down movements in its wake and creating increased potential for concentrations and fallout conditions along the Texas coast. However, conditions are forecast to be marginal in portions of the source areas to the south, so numbers of migrants may be diminished if these events occur. Additionally, birders in the western Gulf should examine the composition of migrants they encounter carefully, as easterly flow may bring more typical Caribbean migrants farther west than normal. By Wednesday night much of the region away from Texas will see light to locally moderate conditions as the unfavorable conditions press east of the Piney Woods and Ozarks. Gradually more favorable conditions continue to return to the region bringing more moderate and heavy movements through end the period, with the exception of the Florida Peninsula. Species on the move this week will include Red Knot, White-rumped Sandpiper, Black Tern, Yellow-billed Cuckoo, Common Nighthawk, Yellow-bellied, Acadian, Alder , and Willow Flycatchers, Northern Waterthrush, Tennessee, Nashville, Cape May, Black-throated Blue, Palm, and Yellow-rumped Warblers, Clay-colored, Savannah, White-throated, and White-crowned Sparrows, Rose-breasted Grosbeak, and Baltimore Oriole.