Forecast and Analysis

Regional Migration Forecasts: 18-25 October 2012

Andrew Farnsworth The Cornell Lab Oct 18, 2012

The West will experience light migration in areas away from the immediate Pacific Coast and elsewhere that precipitation is forecast, whereas strong high pressure in the Southeast creates favorable conditions for moderate to heavy movements in the Northeast and generally unfavorable conditions in the country’s midsection. A brief note – birders in the Upper Midwest, Northeast, and portions of the mid-Atlantic states should watch for Cave Swallows in the wake of low pressure passing this weekend.

Coastal precipitation in the Pacific Northwest will shut down movements to begin the weekend, and precipitation will continue to shut down movements as this rain continues and expands to more southerly portions of the coast and into the Sierras by the middle of the coming week. Some portions of the Great Basin and central Rockies will also see scattered precipitation to similar ends in terms of bird movements. Elsewhere in the region, migration will be primarily light as high pressure over the Four Corners persists for much of the forecast period.

Great Plains
Migration will be moderate to high in many areas to begin the weekend following a low pressure system moving across the Upper Mississippi River valley and ensuing northerly and northwesterly flow. As high pressure builds into the Southeast, winds become less favorable to end the weekend and diminish movements to light to moderate levels in most areas. These unfavorable winds continue into Tuesday, when a disturbance passes through the central Plains. This system may bring more favorable conditions to the Dakotas and Minnesota, with more moderate to high movements possible. More intense southerly flow follows for Wednesday and Thursday, and most birds will likely stay where they are on these days and nights. The next large scale system moves into the region by 25-26 October, and interesting and potentially favorable migration conditions may occur to end the forecast period depending on the system’s speed and intensity.

Upper Midwest and Northeast
Low pressure moves across the Great Lakes by Friday night and Saturday morning, creating favorable conditions for moderate to heavy movements in the Upper Mississippi River valley and western Great Lakes and unfavorable and messy conditions across much of the region east of those places. As the system passes east and north on Saturday night, moderate to heavy movements will occur in many more areas in favorable conditions with the exception of portions of New England. By Sunday night, westerly flow across the entire region will bring light to moderate movements in western locales, and moderate to heavy movements in the east, primarily east of the Appalachians. Sunday and Monday mornings may see very nice later migrant morning flight occurring in coastal areas in the stronger westerly winds. High pressure in the Southeast brings continued favorable conditions for moderate to heavy movements through Monday night in many areas east of the Appalachians. However, areas west of the Ohio River valley and through the Great Lakes will see limited movements in southerly winds and rain. Similar conditions prevail through midweek and into the end of the forecast period. Many areas of the Northeast may see several nights of favorable conditions for migration, suggesting that many of the remaining Neotropical migrants and many later season migrants will be on the move. Additionally, increasing numbers of waterfowl should be apparent during diurnal skywatching and nocturnal listening. Furthermore, later season raptor migration should be in full swing, particularly from Monday through Thursday. Birders should also be alert to the possibility of Cave Swallows in the region in the wake of the passage of low pressure between 19-20 October.

Gulf Coast and Southeast
High pressure moving into and through the lower Mississippi River valley over the weekend will bring favorable conditions for moderate movements to many areas of the Southeast away from central and eastern Texas and the immediate Atlantic coast. As this high pressure center parks itself in the Carolinas on Sunday night and Monday, primarily moderate movements will prevail east and southeast of the Appalachians while scattered light to moderate movements will occur farther west in southerly flow. This pattern continues and shifts even farther east through the end of the forecast period, with all areas but the immediate Atlantic coastal plain and the Florida Panhandle experiencing limited movements.