Fierce North Atlantic storm to send temperatures soaring at North Pole (again)

Hurricane-force low pressure system seen on Feb. 6, 2016.
Image: nasa worldview

An extraordinarily powerful storm system is spinning across the North Atlantic Ocean, just southeast of Greenland. Together with long-term climate change and other transitory weather systems, it is setting the stage for a dramatic and unusual warmup at the North Pole this week.  

For the third time this winter, such a storm is likely to vault unusually warm air toward the pole, potentially bringing temperatures across the sunless Arctic to near the melting point for a brief period late this week. 

The storm, an unnamed beast that looks like it came straight from meteorological central casting, exploded in intensity on Sunday. The air pressure at the center of the storm bottomed out at an astonishing 932 millibars, or 27.52 inches of mercury on a home barometer. In general, the lower the pressure, the stronger the storm, and a reading this low indicates that the storm means business. 

In fact, such a low pressure reading is more typically seen in Category 3 or 4 hurricanes, although this particular tempest is not tropical in origin, and therefore was not given a name by the National Hurricane Center.

The National Weather Service's Ocean Prediction Center (OPC) has been keeping an eye out on this storm for a while. In fact, the center predicted that the storm would develop and intensify into a dangerous low pressure area that could doom ships caught in its path. 

According to the OPC, the weather system has clocked in with winds as high as 90 miles per hour, and churned up waves of greater than 46 feet along its southeastern flank.

Arctic heat wave

While this powerful storm is noteworthy on its own, its impacts across the Arctic will be especially significant. 

The Arctic has had a freakishly warm winter to follow its warmest year on record. Sea ice extent continues to limp along at an anemic record low for this time of year, due to weather patterns and long-term climate change. The Arctic is warming at twice the rate of the rest of the globe, mainly because of feedback loops in the climate system that kick in as snow and ice melts and darker land and sea surfaces are exposed to the sun.

This winter has been anything but typical in the far north. On at least two occasions, so far, the North Pole itself has neared or reached the melting point of 0 degrees Celsius, or 32 degrees Fahrenheit, in part because of pulses of mild and moist air flooding the region from the Atlantic side of the Arctic Ocean.

On Thursday, temperature departures from normal of 50 to 60 degrees Fahrenheit are projected for areas near the North Pole. Such anomalies would take actual air temperatures to near the melting point. 

This particular storm will cause the third such event since November, as the counterclockwise flow of air around the low pressure area teams up with the circulation around a high pressure area over northern Europe, funneling mild air toward the North Pole.

While these relatively brief Arctic warmups are not unheard of, having so many of them in a single winter is rare. 

If this situation seems familiar to you, it's because a nearly identical event occurred in December 2015, causing alarm over a melting North Pole. 

During the last warm Arctic event, experts said that while storm systems are the major player in causing transient and dramatic warm spells, such events are most likely enabled by low sea ice cover as well.

The second-lowest sea ice cover on record in the Arctic was recorded in September, and recent months have set monthly records as well.

In the summer and fall, missing sea ice cover allows ocean waters to absorb heat from the sun, which is then slowly released into the air in the fall and early winter. Ice-covered areas stay cooler since sea ice reflects most incoming solar radiation.

A study published in Nature Scientific Reports on Dec. 15 found that North Pole winter warming events are associated with low pressure systems, or cyclones, near the pole, as well as a polar vortex that is "perturbed," or weakened, which allows for areas of extreme cold to leak out into the midlatitudes. 

Top-down view of the Arctic Ocean with arrows indicating warm air transport from the North Atlantic Ocean.


Image: weatherbell analytics/mashable

Both of these conditions are present this week, and have been at other times this winter. 

The author of that Nature study, Kent Moore, a physics professor at the University of Toronto, said in December that records of such events go back at least to 1959, with an observed frequency of about once or twice each decade. 

While there isn't a clear indication that these events are becoming more frequent, Moore said the magnitude of the temperature extremes are growing at twice the rate of general Arctic warming. 

Temperature anomalies projected for the Arctic on Thursday, Feb. 9, 2016.


Image: weatherbell analytics

Moore says this is consistent with the loss of winter sea ice near Norway, which allows a "reservoir" of warm air to move closer to the Pole, where storms can tap into it. 

"We’re getting to the point where extremes are becoming more extreme,” Moore said. 

According to Moore, sudden warming events like this one can cause serious problems for Arctic wildlife by causing rain to fall on top of snow, leading to an icy crust that prevents reindeer herds from accessing their food beneath the snow.

