Ovenbird. Anonymous eBirder/Macaulay Library. 26 Mar 2016. eBird S28566155
Warming conditions, occasionally punctuated with scattered precipitation, will generally see light to moderate flights featuring Common Loon, White-faced Ibis, Bonaparte’s Gull, Caspian Tern, Nashville Warbler, Black-throated Gray Warbler, and Yellow-headed Blackbird across the West, particularly during the second half of the period, while a cold and quiet start to the weekend in the East will change markedly to begin (and end) the work week with moderate to locally heavy flights that include Little Blue Heron, Lesser Yellowlegs, Hudsonian Godwit, Whimbrel, Common Tern, Chuck-will’s Widow, Hermit Thrush, Blue-winged Warbler, Worm-eating Warbler, Scarlet Tanager, and Savannah Sparrow.
Wondering what species are migrating through right now? Check out our analysis for the past 7 days.
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.
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A cold, wet, and generally quiet start to the weekend will stand in stark contrast to Sunday’s conclusion, when warmer temperatures and southerly flow will usher a pulse of moderate movements into and across the region. Some of these will be locally heavy. Birders should watch these movements carefully, as a strong frontal boundary will interact with birds aloft and potentially create concentrations and fallouts in zones where birds and precipitation overlap. The cold front’s passage shuts down movements for Tuesday and Wednesday, as cooler and northerly flow spreads across the region. And these effects persist through the end of the period east of the Appalachians, where the influence of high pressure will keep most movements light and scattered. Note, however, that west of the Appalachians, the forecast is more favorable; beginning on Wednesday moderate to heavy flights will occur in these more favorable conditions, first in the Midwest and gradually spreading into more eastern locations on Thursday.
A brief aside – the polar vortex that is and will continue to keep much cooler temperatures in place in the region is also influencing the formation of a strong high pressure center over Greenland (a “rex block” – see this old gem). This high pressure typically creates a circulation favorable for bringing European vagrants to northeastern North America (particularly on the front lines of Newfoundland). Birders in coastal New England and Maritime Canada should stay alert for such goodies as Northern Lapwing, European Golden-Plover, Black-tailed Godwit and more in the coming two weeks.
A slow start to the weekend, with locally moderate flights primarily occurring west of the Mississippi River, will gradually shift to more exciting migration moments by Sunday and Monday. Building high pressure, and associated southerly flow, returns to the region and will spawn moderate to heavy flights. By Monday night, a frontal boundary approaches the Gulf Coast, suggesting birders east of the Mississippi River should be on the look out on Tuesday for coastal fallouts and concentrations. As this frontal boundary pushes farther east, and bows farther south, birders farther west along the Gulf Coast should watch for similarly interesting conditions on Wednesday. By Thursday much of the migration system across the region shuts down in the northerly flow in the frontal passage wake. However, signs of life return to the western Gulf to end the week, as more favorable conditions also return and bring moderate to locally very heavy flights.
Worm-eating Warbler. Robert Norton/Macaulay Library. 30 Mar 2016. eBird S28663287
A brief pulse of moderate to locally heavy flights will come to the region on Friday and Saturday nights, as a warm air mass builds into the region. A low pressure system moving east puts an end to that excitement by the end of the weekend, quieting movements in the region until Tuesday night. But from Tuesday night through the end of the period, a consistent presence of warming temperatures and southerly flow will see moderate to heavy flights become increasingly widespread through the end of the period.
Little Blue Heron. Rob Francis/Macaulay Library. 7 Apr 2016. eBird S28800349
Light to moderate flights in the Great Basin and Rockies will kick off the weekend, while scattered precipitation makes for widely scattered flights in other areas of the West. This scattered precipitation expands as a manifestation of generally marginal conditions for the days that follow, with most movements scattered and light for the region. Note, however, that the northern Rockies and Montana will experience some favorable conditions for moderate flights on Monday night. A similar pattern of scattered precipitation continues for the remainder of the week, although generally warming temperatures and increasing southerly flow will allow for light to moderate movements in areas where precipitation does not fall.
Savannah Sparrow. Dan Murphy/Macaulay Library. 6 Apr 2016. eBird S28786728