Forecast and Analysis

Regional Migration Forecast: 15-22 March 2013

Andrew Farnsworth The Cornell Lab Mar 15, 2013

Continental Summary

This week’s migration forecast highlights favorable conditions for migrant arrivals in the Gulf Coast region and unfavorable conditions for migrants to advance into much of the West, Great Plains and Upper Midwest and Northeast because of late winter-early spring storms moving east during the forecast period.

Forecast 925mb winds and precipitation for 15-22 March 2013.

Forecast 925mb winds and precipitation for 15-22 March 2013.

West

Several storms systems will keep migrants grounded in many areas, although light migration will occur sparsely across some areas with favorable conditions.

Scattered light migration may occur over portions of the West during the weekend, but conditions are largely unfavorable for more extensive movements. With storm systems passing from the Pacific Northwest eastward across the Northern Rockies, any movements will likely be farther to the south in California and the Desert Southwest. Tuesday and Wednesday will likely see the most widespread light movements, followed by another shut down as low pressure once again moves across the region into the Rockies. Thursday night, 21 March, may see localized light to moderate movements in portions of the southern Rockies as the low passes the Four Corners region.

Great Plains

Cold air and a strong late winter-early spring storm shut down some movements, but southerly flow, particularly later in the period, bring more spring arrivals in more widespread light and moderate nocturnal movements and some diurnal movements.

The region is divided to begin the weekend with light to moderate migration occurring in the southern Plains and little movement farther north. Sunday night should see more widespread light to moderate movements as a low pressure center moves across the Dakotas, spawning favorable conditions for waterfowl, early shorebirds, and early passerines to migrate. Although this fast moving storm system shuts down movements across the region, its effects are ephemeral as southerly flow returns by Wednesday and Thursday, spawning more light and moderate movements from the Gulf coast to the Canadian border. Skywatchers should plan to watch for diurnal movements of raptors, waterbirds, and some passerines on Wednesday and Thursday.

Upper Midwest and Northeast

Primarily unfavorable conditions with inhibit most movements, although a pulse of migration will likely occur early in the week as a strong low advances to the region.

Unfavorable conditions will keep migration mostly light and scattered through the weekend, as primarily northerly and westerly flow prevails. By the beginning of the week, however, things change – strong southerly flow in advance of a storm system moving out of the northern Plains should facilitate good diurnal movements across the Upper Midwest on Monday and light to locally moderate nocturnal movements on Monday night. As the storm system passes, migration shuts down across most of the region through the remainder of the period, with the possible exception of the Upper Mississippi River valley and western Great Lakes.

Gulf Coast and Southeast

Generally southerly flow brings several waves of new migrants, though an early week storm system briefly shuts down movements.

As high pressure moves East across the Florida peninsula, increasingly favorable conditions spread over the Gulf of Mexico for trans-Gulf migration to occur. New arrivals of earlier waterbirds and songbirds should be apparent later in the weekend and through much of the forecast period. ┬áPrecipitation is forecast to reach the Gulf Coast on several days, particularly early in the week. Birders in the eastern Gulf states should watch this carefully – although it is still early in the season, fallouts of early trans-Gulf migrants could occur in typical coastal hotspots of Alabama and the Florida Panhandle. Light and moderate migration prevails through the weekend and early week in many areas, but the low pressure system passing north of the region shuts down flights by midweek. As high pressure builds behind this system and moves east, favorable southerly flow spawns more light and moderate movements, particularly to the West of the Mississippi, to end the period.

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