Warm, Wet Year for U.S.

Many Americans were throwing on T-shirts or rain gear instead of heavy coats last month, in what proved to be the nation’s mildest and wettest December in more than a century of record-keeping. On Thursday, NOAA’s National Centers for Environmental Information (NCEI) released initial data on December and for the year 2015.  (A full report will be issued on January 13).  As a whole, 2015 came in as the second warmest and second wettest year on record for the contiguous U.S.

It’s hard to overstate the striking character of December’s mildness.  Millions of people along the Eastern Seaboard experienced it first hand, as all of the big cities (and many smaller ones) from Washington, D.C., to Portland, Maine, smashed their previous records for December warmth. New York City’s Central Park went through the entire month of December without dipping down to freezing, whereas all prior Decembers back to 1871 had reached 32°F at least six times.  As shown in Figure 1, each state east of the Mississippi--plus Minnesota, Iowa, and Missouri--saw its warmest December on record, and even the coolest states were close to their long-term December average.  All told, close to 12,000 daily records (warm highs and warm lows) were set across the nation in December, as noted by weather.com.  There was plenty of moisture to be had as well:  40 states came in above average on precipitation, with Iowa and Wisconsin getting their wettest December on record and Minnesota, Missouri and Illinois coming in at second-wettest. These rains contributed to the exceptional flood crest now moving along the lower Mississippi River.

For the year as a whole, the warmth and moisture were widely distributed across the contiguous U.S.  There were more than twice as many daily record highs as record lows for the year, but as noted by Climate Central, a brutally cold February over the eastern U.S. was the main factor keeping 2015 from being the nation’s warmest year.  The northwest and southeast corners of the 48 states, Washington and Florida, both had their warmest year on record, as did Oregon and Montana.  All 48 contiguous states saw at least a top-25 warmest year.  Only five were notably drier than average in 2015--California, Montana, Connecticut, Rhode Island, and Massachusetts--while many central states had a top-10 wettest year, with Texas and Oklahoma notching their wettest on record.  (During the first week of 2016, moisture has also returned to California in a big way, thanks to a parade of soggy Pacific storm systems; more on that in a future post.)

Read more at Warm, Wet Year for U.S.; Record Heat in South Africa; Tropical Storm Pali Intensifies