North American Birds

VOLUME 69 NO3 2016

A Quarterly Journal of Ornithological Record Published by the American Birding Association. The mission of the journal is to provide a complete overview of the changing panorama of our continent’s birdlife.

Issue link: http://nab.aba.org/i/778845

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Figure 1. Observed temperature change in the United States of America. The colors on the map show temperature changes over the years 1991-2012 in degrees Fahrenheit compared to the 1901-1960 average (or the 1951-1980 aver- age for Alaska and Hawaii). It is worth nothing that the period 2001-2012 was warmer than any previous decade in every region of the United States. Graphic courtesy of and copyright the United States National Climate Assessment and Development Advisory Committee, National Climatic Data Center, National Oceanic and Atmospheric Administration. 342 N O R T H A M E R I C A N B I R D S The Changing Seasons: Retrospect The Changing Seasons: Retrospect EDWARD S. BRINKLEY • 124 PEACH STREET • CAPE CHARLES, VIRGINIA 23310 • (THALASSOICA@GMAIL.COM) The Weather Spring and summer 2015 were the eleventh and twelfth warmest on record in the contig- uous United States, with spring 2.2° F above the twentieth-century average and summer 1.4° F above. In spring, Florida was record warm, while large portions of the South- east, Midwest, and West were much above average. March and much of April were cool, in some cases almost record cold, in the Northeast, but that trend was broken in May, which was record warm. On the Pacific coast, California, Oregon, and Washington posted their record-warmest summers, and June was particularly warm—in fact, it was the second warmest June on record for the contiguous United States. Warm tempera- tures in the West especially meant that snow cover extents were the lowest ever measured in the Lower 48 states, some 938,353 km 2 (362,300 mi 2 ) below the 1981-2010 aver- age, the least in the five decades of record- ing. The Midwest and Northeast, which had heavy snows in winter and relatively cool early springs, had above-average snow cover well into April. Overall, the seasons' precipitation levels were above average, with spring about the tenth wettest and summer the sixteenth wet- test on record. The Southern Great Plains, Southern Rockies, and Lower Mississippi River valley were particularly wet, especially in May. In fact, May 2015 ended up being the wettest month (of any month) ever re- corded in the contiguous United States. So much rain fell in the continent's center in spring that persistent drought conditions in Texas and Oklahoma were erased. The Carolinas received heavy rains from Tropical Storm Ana, which made landfall 10 May at Myrtle Beach, South Carolina. Widespread rains in spring reduced drought conditions in the Lower 48, from 31.9% of those states' land areas in early March to 24.6% by the end of May. But the lack of snowpack from the winter meant that drought in the Pacific Northwest intensified across large areas. In June, above-average precipitation lev- els were boosted tremendously by the re- mains of Tropical Storm Bill, which made landfall at Matagorda Island, Texas 16 June. Hawaii was rather dry during both seasons but in August finally enjoyed beneficial (and record-breaking) rains from the remnants of three storms: Hilda, Kilo, and Ignacio. By contrast, Puerto Rico endured steadily worsening drought conditions through the two seasons, from 17% in spring to 64% at summer's end. The eastern end of the is- land was in extreme drought, but this was anticipated because of the El Niño condi- tions, which are strongly associated with dry spells in the Greater Antilles. Overall during summer, the contiguous states saw drought conditions expand, ending in Au- gust at about 30.4%. The Southwest and Northeast had above-average summer rains, while the Southeast, Lower Mississippi val- ley, and Great Plains were much drier, with some areas slipping back into drought cate- gorization despite plentiful spring rains over much of these regions. In short: global warming continues, and notable cycles of drought and deluge con- tinue. Much of the increasing warmth in the atmosphere emanates from the warm- ing oceans. In 2015, the average tempera- -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 Temperature Change (ºF) • Observed U.S. Temperature Change •

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