Daily high temperature departures from average for February so far. Notice a dominant color? Image: weatherbell analytics
There's something about a warm February day that reminds you that something just isn't right. It gives you that nagging feeling that maybe global warming is real after all...
February 2016 has featured prolonged warm weather the likes of which many areas have not seen before, or have only experienced on rare occasions.
Taken as a whole, the month-to-date in the U.S. has seen a ridiculously lopsided ratio of daily record highs to daily record lows, which is a key indicator of short-term weather variability and, over the longer term, human-caused climate change.
For individual days' worth of warm weather, you mainly have the jet stream to thank. This current of fast-moving air at about 35,000 feet above the ground has been steering a never-ending series storms into the West Coast, where California's mountains have picked up a crazy 500 inches of snow so far, and then moved across the U.S. in a way that has cut off flow of frigid air from the Arctic.
While transient weather variability is playing a key role here, the widespread record warmth across the U.S. so far this year is part of a long-term trend toward more warm temperature records versus cold ones.
This February offers a vivid illustration of this trend.
Through Feb. 23, daily record highs have been blowing away daily record lows by a far greater than 100-to-1 ratio, which, if it holds for a few more days, would itself set a record. So far this month, there have been nearly 5,000 daily record highs set or tied, compared to just 42 daily record lows. (Although this records ratio might need an asterisk, considering the short calendar month.)
And it's not the daily records that are most impressive, but rather the number of monthly records that are being tied or broken from the Gulf Coast all the way to the Midwest and northeastward into Canada. During the past week alone (not including Feb. 23), there were 736 daily record highs set or tied in the U.S., compared to zero daily record lows for the same period.
Even more startling is the number of record warm overnight temperatures set or tied in the past seven days, which total a whopping 940. There were no record cold overnight low temperatures set or tied during the same period.
And the monthly records, which are far harder to break than daily milestones, are astounding.
Temperature anomaly across North America for Feb. 19 as seen through the GFS computer model. Image: weatherbell analytics
According to the National Center for Environmental Information (NCEI) in Asheville, North Carolina, February has seen 336 monthly record highs set or tied, along with 203 records set or tied for the warmest overnight minimum temperature. In comparison, there was not a single monthly cold temperature record set or tied through Feb. 23.
These figures do not include monthly temperature records that were broken on Friday, which included 73 degrees in Boston, shattering the previous record by 3 degrees Fahrenheit. In addition, Allentown, Pennsylvania hit a remarkable 77 degrees, and Binghamton, New York reached 70 degrees Fahrenheit. Dayton, Cincinatti and Columbus Ohio each either tied or broke their monthly high temperature records on Friday as well, with numerous monthly milestones set on Thursday, too.
In Albany, New York, the high temperature of 74 degrees on Thursday was the warmest temperature on record for any day during the months of December, January and February.
On Wednesday, the record warmth was centered across the Midwest, where the three major cities in Wisconsin (Milwaukee, Madison and Green Bay), all saw temperatures hit record highs for not just February, but for any month during meteorological winter, which encompasses the months of December, January and February.
Milwaukee, for example, broke its monthly all-time record high for February when the temperature reached 71 degrees Fahrenheit, and Madison set a monthly record with a high of 68 degrees Fahrenheit.
In Ottumwa, Iowa, where the ground would normally be snow-covered this time of year, the high on Wednesday was 79 degrees, which set a monthly record as well. Some cities set records for the longest stretch of February warmth they've seen, including Kansas City, which set a seven-day February warmth record on Wednesday, according to weather.com.
On Monday, Chicago had a high temperature of 70 degrees, which was only the fifth time that has happened in any February in the "Windy City." (The fourth time also came this February.)
The warm weather in the Midwest was enabled by a marked lack of snow cover and lake ice across the Great Lakes, which allowed air temperatures to soar on mild southwesterly winds for days on end. As of Feb. 22, just 19.1 percent of the lower 48 states were snow-covered, far below average for this time of year.
While cold air is staging a comeback across the Midwest, where heavy snow is predicted to fall from Nebraska into Wisconsin, much of the South and East is likely to stay milder than average for at least a few more days.
Where's the snow? Image: noaa
The warm weather in the U.S. hasn't been a freak phenomenon only occurring for the past few weeks, either. The year-to-date is averaging a record daily highs to record daily lows ratio of more than 4-to-1, and studies have shown that over the past several decades, human-caused global warming has increased the odds of warm temperature records so that these ratios are becoming more and more skewed.
And the warmth isn't just limited to the U.S., either, with the planet recording its 3rd-warmest January on record, after its warmest year so far in 2016. This continues the long-term warming of about 1.7 degrees Fahrenheit since reliable surface temperatures began in 1880.
As the planet warms in response to the buildup of greenhouse gases in the atmosphere, the ratio of high temperature records compared to low temperature records has become more skewed. If the climate weren't warming, that long-term ratio should average out to about 1-to-1.
However, that isn't the world we're living in. A 2009 study found that the record highs to lows ratio was 2-to-1 for the lower 48 states during the 2000s, and this disparity has only grown since then, though not evenly across every part of the country. Projections show the imbalance increasing in coming decades as global warming continues, possibly to as high as 15-to-1 if emissions of planet-warming pollutants such as carbon dioxide continue apace.
"One thing I remind myself when comparing contemporary events to trends or patterns is that the contemporary events themselves make up the trends and patterns," said Deke Arndt, who leads the climate monitoring branch at NCEI. "This is a real-time view into what we will call "recent trends" in a few years."
"This week has been an up close look at the DNA of what we are seeing in the big picture: relative to historical norms, extreme heat continues to outpace extreme cold across almost every place, season and time of day in the USA."
While individual months will still vary from this trend, it's clear that over the long-term, the ratio of record highs to record lows is now strongly favoring record highs as well as record warm overnight temperatures. This is consistent with computer model projections of a warming world.
In other words, if you like 70-degree February days in Washington, D.C., you're in luck.
The odds are (increasingly) ever in your favor.
Feb 24, 2017
original story HERE
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