Forecast and Analysis

Regional Migration Forecasts: 8-14 March 2013

Andrew Farnsworth The Cornell Lab Mar 08, 2013

Continental Summary

This week’s migration forecast highlights the effects of a strong frontal boundary crossing the country, facilitating light and scattered moderate movements with its approach to a region and shutting down migration in its wake.

Weather Map for Forecast Period 8-14 March 2013

Click the image to view a larger version of this loop.


Generally unfavorable conditions ground most migrants, although scattered light migration will occur in isolated areas with more favorable conditions.

Scattered light migration in the Pacific Northwest may be apparent to begin the forecast period and the weekend. However, stormy conditions will shut down movements by Sunday through the end of the period. The Northern Rockies should experience light migration on Sunday to begin the week, but conditions deteriorate as the week progresses and unfavorable conditions spread to the East. A disturbance passing through the Desert Southwest and the Central and Southern Rockies will keep most migrants grounded until Sunday night. However, clearing skies and light winds through the remainder of the forecast period will facilitate scattered light migration, particularly by Wednesday and Thursday.

Great Plains

Another winter storm moving through the region shuts down migration early in the period, but building high pressure brings more favorable conditions for light and moderate movements late in the week.

Southerly flow prevails as a storm system moves east across the Rockies, facilitating light to moderate migration in many areas from Texas into the central Great Plains. However, precipitation farther north will shut down these movements, and may even spawn local fallouts of waterfowl and early season migrants. Unfavorable conditions follow the passage of this system, but by Tuesday night some areas of the central Plains should again experience light migration. As high pressure builds over the Mississippi River valley and spans a large area of the Southeastern US, light winds should facilitate more widespread light and scattered moderate movements in many areas by mid-week.

Upper Midwest and Northeast

A brief respite with some favorable conditions for light and moderate migration is sandwiched between an exciting winter storm and a new approaching frontal boundary.

The weekend begins with northerly and northeasterly winds continuing to produce good sea-watching conditions along the immediate coast but poor conditions for most migrants. However, diminishing winds with this system’s exit and southerly flow in advance of the next low pressure center’s arrival bring more favorable conditions to the Upper Midwest. Light migration with locally moderate migration should occur over the weekend, and birders should watch for potential fallout conditions in any inland bodies of water as the low passes and precipitation falls. Although these more favorable southerly winds continue east over the early part of the week, unfavorable flow behind the frontal boundary quickly overspreads the region and shuts down migration through the end of the period.

Gulf Coast and Southeast

A frontal boundary crossing into the Gulf of Mexico may bring very early spring fallouts along coastlines, but unfavorable conditions in the wake of the cold front shut down movements by mid-week.

Southerly and southeasterly flow across the Gulf of Mexico to begin the forecast period should facilitate early arriving trans-Gulf migrants from Texas through Alabama. However, by Sunday night an approaching frontal boundary pushes off the coast. Although early in the season, birders should watch for fallouts in coastal locations, particularly for some of the earliest trans-Gulf migrants (e.g. early waterbirds and passerines). Additionally, southerly flow ahead of the frontal boundary should facilitate light to moderate migration from the Mississippi River Valley east through the Appalachians as the system approaches. With the passage of the low-pressure center, however, unfavorable conditions across the region and for trans-Gulf flights build in from the West and continue for the duration of the forecast period.