Continental Summary
Scattered light to moderate movements that begin the weekend give way to much more widespread movements to end the period in the West, while moderate to heavy movements will occur in many areas of the East as low pressure organizes and moves off the coast (and begets more Gulf Coast fall outs). Species on the move this week will include White-faced Ibis, Wilson’s Phalarope, Forster’s Tern, Common Nighthawk, Chimney and Vaux’s Swifts, Northern Flicker, White-eyed and Blue-headed Vireos, House Wren, Western, Scarlet, and Summer Tanagers, Blue, Rose-breasted, and Black-headed Grosbeaks, and Baltimore Oriole.
Arrows show wind speed and direction 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.
West
Favorable conditions prevail in the southerly portions of the region to begin the weekend, facilitating light to moderate movements. However, as the weekend continues, these movements become increasingly restricted to local movements as less favorable conditions take hold. By Monday favorable conditions begin to ease into the Pacific Northwest and northern Rockies, overspreading much of the rest of the region by Tuesday. These conditions will spawn widespread light to moderate movements in many areas, with heavier movements possible in portions of California and the Pacific Northwest. Passing disturbances late in the week will make movements more scattered and local, but favorable conditions continue in many areas where precipitation is not falling. Some areas in the Desert Southwest and just east of the Rockies may experience heavier flights during the mid to late week time frame, as southerly flow in those areas will create highly favorable conditions for nocturnal and diurnal movements. Species on the move this week will include White-faced Ibis, Semipalmated Plover, Western Sandpiper, Wilson’s Phalarope, Vaux’s Swift, Northern Flicker, Ash-throated Flycatcher, Varied Thrush, Ruby-crowned Kinglet, Nashville and Hermit Warblers, Yellow-breasted Chat, Brown-headed Cowbird, Summer and Western Tanagers, Lazuli Bunting, and Blue and Black-headed Grosbeaks.
Great Plains
Moderate to heavy movements will kick off the weekend in the Plains as southerly flow spreads across much of the region. As a disturbance with associated precipitation moves through the region, migration will become less apparent from north to south, with a nearly complete shut down by Monday morning. Birders should watch the incursion of precipitation into the area early Saturday morning, and again on Sunday, as some of the nocturnal movements may interact with precipitation (particularly on Sunday) and spawn fallouts and concentration. By the middle of the week, favorable conditions will return and spread across most of the region, bringing a new pulse of moderate to heavy movements. These movements continue through the remainder of the week, but they become less widespread as some changeable conditions including unfavorable winds and precipitation appear scattered across the region. Species on the move this week will include White-faced Ibis, Semipalmated Plover, Willet, Hudsonian Godwit, Spotted Sandpiper, Wilson’s Phalarope, Forster’s Tern, Chimney Swift, Northern Flicker, Eastern and Western Kingbirds, House Wren, Golden-crowned Kinglet, Yellow-headed Blackbird, Summer Tanager, Indigo Bunting, and American Tree, Song, Fox and Lark Sparrows.
Upper Midwest and Northeast
An area of precipitation and unfavorable winds sitting over the northern portions of the region keep most migrants on the ground to begin the weekend, while scattered light to moderate movements occur elsewhere in portions of the Great Lakes and central Mississippi River valley. More favorable conditions arrive by Saturday night, with much more widespread moderate and even heavy movements. Great Lakes birders should watch for fallouts and concentrations, as migrants will likely encounter precipitation on Saturday night and Sunday morning. The pattern continues through Sunday into Monday, with widespread favorable conditions spawning movements in many areas away from the immediate Great Lakes; in that area a cold front with precipitation continues to have the potential to create fallouts and concentrations of waterbirds and land birds. As the front moves east, favorable conditions become increasingly coastal and moderate to heavy movements will occur mostly in these areas, until finally the whole of the region is bathed in unfavorable conditions as low pressure exits to the east. After this passage of this system, changeable conditions remain in place through the rest of the period; light to moderate movements will be scattered and local, with the best chance for more widespread movements on Thursday night from the Ohio River valley east through New England. Species on the move this week will include Bufflehead, Green Heron, Broad-winged Hawk, Spotted Sandpiper, Chimney Swift, White-eyed and Blue-headed Vireos, Barn Swallow, House Wren, Blue-gray Gnatcatcher, Golden-crowned and Ruby-crowned Kinglets, Yellow-rumped, Prairie, Yellow, and Prothonotary Warblers, Common Yellowthroat, and Dark-eyed Junco.
Gulf Coast and Southeast
Mostly favorable conditions across the region spawn moderate to heavy movements for much of the weekend. A cold front arrives by Sunday night, and once again brings the likelihood of fallouts from the Upper Texas Coast east through Mississippi by Monday afternoon. Precipitation is forecast to spread over much of the Gulf of Mexico by Monday night and Tuesday, so the potential for fallouts expands to include more of the Gulf Coast. This potential will depend heavily on the conditions for migrant departure, which as of now are still favorable in Yucatan and portions of northern Central America and the western Caribbean. The whole migration system over water and over land shuts down by Tuesday night, as the front moves east across Florida. Moderate to heavy movements return on Wednesday night, away from the southeastern US where unfavorable winds prevail in the wake of frontal passage; and this pattern continues to end the period. Note that easterly flow across the region early in the period could bring more typically eastern Gulf of Mexico and Caribbean migrants to Texas and Louisiana, so birders there should watch for Black-throated Blue and Cape May Warblers among others. Species on the move this week will include Green-winged Teal, Belted Kingfisher, Yelllow-bellied Sapsucker, Common Nighthawk, Swainson’s and Wood Thrushes, Northern Waterthrush, Black-throated Blue, Cape May, Yellow-rumped, Yellow and Blackpoll Warblers, Yellow-breasted Chat, Baltimore Oriole, Scarlet and Summer Tanagers, Painted Bunting, Blue and Rose-breasted Grosbeaks, Field and Chipping Sparrows, Dark-eyed Junco, and Purple Finch.
