The Pole continues to make for interesting theater, though the drama has died down from what it was a week ago, when temperatures were soaring to 35 degrees above normal and the ice at the north edge of Barents Sea was retreating. Fueling this weather was a strong south wind from the Atlantic that at times pushed right past the Pole towards the Pacific, thus confusing everybody, because a south wind became a north wind without changing direction. This flow achieved its peak around November 14:
By November 16 the flow was pushing an Atlantic low and its secondary up through Fram Strait, whereupon, due to the strict laws of this website, they are automatically dubbed “Ralph”. The southerly flow, while remaining southerly, had swung east, and was now coming less off the Atlantic and more off shore from Europe, but it nearly was able to push above-freezing temperatures to the Pole.
So strong was this flow that the sea-ice, which usually is expanding south as a thin sheet of ice, was pushed north by strong wind until it was briefly well north of Franz Josef Land, and unable to refreeze because temperatures were above freezing in that area. This produced a brief and unusual dip in the ice “extent”graph, which usually is rocketing upwards at this time of year. However the ice swiftly grew back down to Franz Josef Lands’s north coast as conditions began to change, and the graph resumed its upward climb.
The surge from the south had raised eyebrows by raising temperatures to unprecedented levels (in a history that goes back 58 years).
However my eyebrows were raised by the steep decline that followed.
This interested me because, whereas other places can get colder air from lands further north, there is no place north of the North Pole. Therefore it must get cold air imported from colder tundra to the south, but I didn’t see any strong flow from such tundras. This meant the cold must instead be home grown. Or, to put it more scientifically, the heat was lost locally, radiated upwards into the unending winter night.
Still, it seemed odd to me that the warm southerly flow should just turn off like a spigot. My curiosity sought reasons, for the cessation was obvious as early as November 17, because the first and second lows, following a storm track straight north to the Pole, (incarnations of “Ralph”), weakened with surprising speed. It was as if they were cut off from their warm inflow of mild, moist air, while the third storm in the sequence came to a dead halt and refused to head north, and just sat off the coast of Norway and twiddled its thumbs, remaining fairly strong.
I wondered if the stalled low off Norway might be consuming all the available energy, but this didn’t satisfy me, for the isobars in the above map still indicate a strong flow from the south. Why wasn’t the warmth heading out over arctic waters? The temperature anomaly map still showed the above-normal temperatures moving north in central Europe, but then being bent east at the top. What was stopping the import of heat north to the Pole?
I’d likely still be mystified, but dawn broke on Marblehead when I visited Joseph D’Aleo’s blog over at the Weatherbell Site, and during the course of one of his elegant descriptions of complex situations he turned on the light-bulb in my noggin.
Just as a meandering stream straightens its course from time to time, cutting across the neck of a loop and leaving an oxbow lake behind
So too can a loopy jet stream decide to straighten up its act, and the “surge” was part of a loopy jet:
When a jet straightens up it act, the cut off part of the stream is not called an “oxbow”, but rather a “cut off”, (which shows that meteorologists are occasionally more sensible than geologists). By November 23 the upper air maps showed the “cut off low” was sitting down over Spain. Over Spain a large part of the surge was no longer heading north, but caught up and going around and around and around, like a taxpayer caught up in a bureaucracy.
You will notice that at the top of the above map the jet is basically zooming west to east. The surge from the south has vanished, making a mess of all my forecasts that calculated the surge would move east this far one day, and this far further east the next. The surge simply disappeared, or at the very least fell over and surged west to east. It was confusing. (Actually the same thing happens when I straighten up my own act. It confuses people who depend on me to be loopy.) In any case, this morning’s surface map had a reflection of the cut-off-low stalled over Spain, but what about the North Atlantic low? It will plow west-to-east across Scandinavia in the jet, nothing like the lows that headed straight north, last week.
The tipped over surge can be seen giving some relief to central Asia in the temperature maps.
In the anomaly map the west-to-east surge looks like an arrow, making a layer cake out of the map (to mix my metaphors). The old cold is to the south, still capable of generating a few headlines, but likely to be slowly moderated out of existence. The new cold is along the top, and likely needs to be watched, for it seems likely to be a lasting feature. The “surge” itself seems likely to linger but weaken, but will remain interesting to watch. At the very least it will give some Asians a break, after they have been through an autumn colder than some winters.
But this is all off the point, which was (in case you can’t remember), that the mild air is not surging up to the Pole any more, and that the vast pool of mild air that was transported up there is slowly cooling, day by day.
I should note that Joseph D’Aleo mentioned that when a jet really gets roaring west to east it can act downright human. (After humans have straightened out their act, what tends to happen next? Answer: Their resolve buckles.) In like manner, we should be on our toes, watching for where the jet will next buckle, and get all loopy, (like a human falling off the wagon after keeping a New Year’s resolution as long as they can bear it). However, for the time being, up at the Pole, “Ralph” has little hope of reinforcements from the Atlantic.
Not that “Ralph” has vanished completely. Largely he has retreated to the Canadian Archipelago, as high pressure dominates the Arctic. At the end of my last post there actually was a small ghost of Ralph by the Pole, and hint of Ralph’s “signature” in the temperature map, hooking mildness towards the Pole, despite the power of the expanding high pressure. (See the tiny low by the Pole?)
The next day Ralph’s ghost was just a dent in the high pressure’s isobars. Freezing temperatures had snuck down to the northeast coast of Svalabard.
The next dawn Ralph, like all good ghosts, was vanishing, because that is what ghosts do at dawn. (If you you squint you can still see a microscopic low under the Pole.) The only real import of air towards the Pole was from central Siberia.
The following dawn saw an odd dimple in the high pressure’s isobars, on the Canadian side. It looked like (if you use your imagination) a face, that the ghost of Ralph had punched. Freezing temperatures were engulfing Svalbard. By evening the ghost of Ralph reappeared, (as good ghosts do at dark), just north of the Canadian Archipelago.
Today saw the freezing isotherm slump well south of Svalbard, and Ralph retreat and regroup north of Canada. Models are suggesting Ralph will soon start attacking the Pole from the Canadian side, though with colder air than before. The North Atlantic flow is totally from the north, and Scandinavia looks likely to get a dose of north winds.
The north winds are allowing the sea-ice to build south again where the “surge” had forced it to retreat, in the north part of Barents Sea, and sea-ice is again touching the north coast of Franz Josef Land. There was also a slight reduction on the Pacific side, due to strong south winds and a brief mild inflow a week ago, but that has been more than made up for by regrowth, which has now engulfed Wrangle Island.
A major difference from last year is that Hudson Bay was half skimmed-over last year, and the refreeze hasn’t even started this year. I think this will soon change. The Bay’s waters are shallow, and it tends to freeze over with remarkable speed, which contributes to the speed of the growth of the “extent” graph. I’ll bet a nickle the Bay is entirely frozen by Christmas.
Even though the flow from central Siberia has been weak, it appears to have nudged the thicker ice just off shore, in the Laptev Sea. Watch for the formation of polynyas along the shore there, for that is indicative of the export of ice into the Central Arctic Basin.
Baffin Bay is swiftly icing over, but remains behind last year’s rate of growth..
The Kara Sea’s sea-ice shrank back before the “surge”, but that sea has since swiftly grown sea-ice on its eastern side.
The reversing winds have seen multi-year ice start down through Fram Strait, along the east coast of Greenland, but the ice down towards the coast opposite Iceland in Denmark Strait is largely home grown.
I’m not sure how it is possible, but some models see a colder version of Ralph moving up from Canada to regain complete control of the Pole in a week to ten days. Stay tuned.