After a burst of cool air last weekend, the mercury continued on its way up again over much of the East.  It's another chapter in what has been an incredibly warm December over much of the Eastern United States, a pattern that some meteorologists have coined the "blowtorch."  Major metropolitan areas in the Northeast saw some of the warmest Christmas Days on record, meaning green grass rather than white snow in time for Santa's visits.  The normal high on Christmas in New York's Central Park is 41 degrees Fahrenheit. Yet the record-high Christmas Day temperature of 64 degrees, set in 1982, was already history as of 2 a.m., and things hardly cooled down from there.  By day's end, five New York area locations -- including Central Park at 66 degrees, plus LaGuardia and Kennedy airports -- had set records.  It wasn't just New York. From 82 degrees in Savannah, Georgia, to 79 in Norfolk, Virginia, to 68 in Philadelphia, to 62 in Portland, Maine, cities up and down the East Coast tied or smashed record high temperatures for Christmas Day.  And while the calendar says winter, these unseasonably warm temperatures are likely to stick around into next week.  The shirts come off on Christmas Eve as a group plays volleyball in New York's Central Park.  The record warmth is not only confined to the I-95 corridor. Record highs were recorded from Texas, through the Gulf Coast, mid-Atlantic and New England. Almost all of Florida was in the 80s, with the 70-degree line reaching as far north as Washington.  Not only have the daytime temperatures been warm, but the nighttime lows in many locations have been running 10 degrees above the normal daily high temperature.  Some meteorologists are pointing to El Niño -- in which warming ocean waters in the tropical Pacific alter weather patterns worldwide -- as the primary cause for such higher-than-average temperatures.  Not only is the United States seeing record temperatures this month, but much of Europe is warm as well. It was nearly 50 degrees in Moscow this week, with puddles, not ice, surrounding the Kremlin.  The higher-than-normal temperatures are forecast to continue for most of the northern half of the United States through the rest of the winter, according to the latest forecast from the Climate Prediction Center.  But what's going on in the United States can't be attributed to El Niño alone.  There's a high-pressure ridge over the East Coast that is causing the warm temperatures. Meanwhile, on the West Coast, there's a low-pressure trough and plenty of snow coming down. Snow in much of the Northwest is above normal already. Even the Sierras in California, which are in the fourth year of a record drought, are well on their way to normal snowfall this year.  There's also a blizzard watch in western Texas, and the clashing of cold and warm air is what's behind some of the severe weather.  What will all this mean for travel in the days ahead?  AAA projects year-end holiday travel will exceed 100 million people this year, which would be a record.  Some in the Southeast got a late start, or got waylaid altogether, by torrential rains and tornadoes.  As of Friday night, 15 deaths in Mississippi, Tennessee and Arkansas had been linked to this severe weather, in addition to scores of injuries. That figure does not include a woman and two small children who died when their car drove into a pond in Clinton County, Alabama, before dawn Friday, County Coroner Aaron Ellison said. Ellison described "very deplorable" weather conditions at the time, but didn't specify that the crash could be blamed on these heavy rains.  The bad weather also contributed to major flooding in many parts of Alabama, which announced Friday that Gov. Robert Bentley had declared a state of emergency for select counties to help authorities handle the damage.  "Flooding is a major concern," Bentley said. "(We) are prepared to respond to any request for assistance."  Those dangers continued Friday with flooding in parts of the Southeast, with tornadoes reported in Alabama. As of 8 p.m. ET, flash flood watches were in effect for parts of 16 states, from Texas in the West to Indiana and Ohio in the north to Virginia in the East.  And the weather won't get much better this weekend in some areas.  Rain and storms continue from Chicago to New Orleans, which could cause minor delays for the major Northeast hubs.  And a new storm is taking shape in the Plains, bringing colder temperatures with it. There could be snow and ice from the Texas Panhandle north to Kansas and Missouri.  CNN's Dave Alsup contributed to this report.
That deep warm feeling on Christmas wasn't just from the glow of the season -- for much of the country, it was from some unusually warm temperatures outside.