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A "potentially historic" winter storm will slam the north-central USA over the next few days with up to 2 feet of snow possible in some areas.
Snow will accumulate from eastern Washington and Montana to Colorado, the Dakotas, Minnesota and northern Wisconsin, the Weather Channel said. Record low temperatures are also possible Thursday and Friday across the western USA.
The system will produce severe storms and heavy rain Thursday in the southern Plains and critical-to-extreme fire weather threats from the central and southern Rockies to California, the National Weather Service said.
The size and intensity of this snowstorm are unheard of for October, according to AccuWeather.
[...] A slew of winter storm warnings, watches and freeze warnings were in effect across parts of seven states as the storm ramped up Wednesday, AccuWeather said.
[...] The storm will have two parts, the first of which is targeting the northern and central Rockies and High Plains on Wednesday into Thursday. The second part will bring snow to the eastern and central portions of the Dakotas and western Minnesota by week's end.
"Near-blizzard to full-fledged blizzard conditions are possible across portions of central North Dakota Friday afternoon into Saturday morning," the weather service in Bismarck said. "Expect high impacts and dangerous to impossible travel conditions."
The weather service called it a "potentially historic October winter storm."
Meanwhile, locations in Kuwait, Saudi Arabia, India, and Australia (among others) reported temperatures well over 100°F (38 C)!
(Score: 5, Informative) by Anonymous Coward on Friday October 11 2019, @05:55PM (11 children)
That's false, or at least quite misleading.
High latitudes are warming much faster than lower latitudes. While it's still quite cold at high latitudes, it's not nearly as cold as it was a few decades ago. The tropics receive more incoming solar radiation than they emit to space as outgoing longwave radiation. The opposite is true at the poles, where they emit more longwave radiation than they receive from incoming solar radiation. There is an excess of heat at the equator and a deficit at the poles, requiring the heat be transported poleward. A lot of this transport is accomplished by monsoons, but extratropical cyclones have a role. Rather than the winds transporting heat directly poleward, the rotation of the Earth and resulting Coriolis effect leads to three cells in each hemisphere, with ascent at the equator, subsidence in the subtropics, and a second area of persistent ascent farther north between mid-latitudes and polar regions.
The boundaries between these cells tend to be associated with a temperature difference over the depth of the atmosphere. Warm air occupies a larger volume than cold air. A warmer column of air, perhaps in an equatorward region of the atmosphere, will be taller than a colder column of air, perhaps in a more poleward region. Air pressure is simply the mass of the air pressing down from above. The temperature gradients in the lower and middle troposphere lead to large pressure gradients in the upper troposphere. These large pressure gradients between the aforementioned cells lead to belts of strong winds in the upper atmosphere, which are known as jet streams.
Because the poles are warming faster than the tropics, the temperature contrast is decreasing. This means that the pressure gradients in the upper atmosphere are also getting weaker, leading to slower jet streams. When we have a strong polar vortex, that is the jet stream at the boundary between the polar and mid-latitude regions is quite strong, the jet isn't particularly wavy, and the cold air generally remains trapped near the pole. When the polar vortex weakens, meaning that the polar jet stream weakens, the jet also tends to become more wavy and the waves in the jet are generally more amplified. This allows cold air to more readily move away from polar regions and into mid-latitude regions.
Because the tropics and poles aren't warming equally, the jet stream is weakening, causing it to become more wavy and the waves to become more amplified. While the air near the poles isn't as cold as normally expected for that region, it's still quite cold by mid-latitude standards. If that not-quite-as-cold air can more readily surge into the mid-latitudes, those regions might see more cold air outbreaks and more extremes. The very wavy jet stream with waves that are more amplified will probably result in slower moving mid-latitude cyclones. The more amplified jet may also more readily advect warm, moist air northward from the subtropics on the warm side of the polar front, possibly resulting in heavier precipitation.
That's the actual theory about how and why global warming may lead to more cold air outbreaks regionally in the mid-latitudes.
(Score: 1, Informative) by Anonymous Coward on Friday October 11 2019, @06:11PM
The difference between the poles and equator is due to geometry. It has nothing to do with heat transport. You see the same effect (of more warming at the poles for the same increase of energy) when considering an object like the moon.
(Score: 2, Touché) by Anonymous Coward on Friday October 11 2019, @07:02PM (5 children)
Say the sunlight is 1360 W at noon at the equator, then it will be 1360*cos(80) = 236 W at noon at 80 degrees latitude
Temperature is proportional to the fourth power of irradiance, specifically according to the Stefan-Boltzmann law:
Lets just call the second term a constant c, then for the temperature at the equator and pole respectively:
Now say you add an extra 100 watts uniformly over the entire surface:
The differences will be:
(Score: 0) by Anonymous Coward on Friday October 11 2019, @09:54PM (4 children)
Except that you forgot to adjust the extra 100 watts by your cos(80) factor. Quoted line 5 should be T_p2 = 253^0.25*c
(Unless you can come up with an isotropic 100watt/m2 energy source.)
(Score: 0) by Anonymous Coward on Friday October 11 2019, @10:04PM (2 children)
That "isotropic source" is supposedly well-mixed CO2 acting uniformly over the entire globe.
(Score: 0) by Anonymous Coward on Friday October 11 2019, @10:53PM (1 child)
If it is acting as a reflector to send 100 watts back down then the radiative temperature of the ground needs to be taken into account. The polar areas are more than 20 degrees cooler than the equatorial areas. Your 100 watts average should be higher near the quator and lower near the poles.
(Score: 1, Touché) by Anonymous Coward on Friday October 11 2019, @11:05PM
Well that makes sense to me. But afaict you are now a climate heretic, because all they do is add an equal magnitude CO2 effect to the entire surface with no regard for that:
https://www.ipcc.ch/site/assets/uploads/2018/03/TAR-06.pdf [www.ipcc.ch]
Can you find an example of someone doing otherwise?
(Score: 1, Informative) by Anonymous Coward on Friday October 11 2019, @10:10PM
And 100 W was just a nice example. In reality it would be more like 3 watts.
(Score: 1, Interesting) by Anonymous Coward on Friday October 11 2019, @07:52PM (3 children)
https://www.nasa.gov/topics/earth/features/warmingpoles.html [nasa.gov]
So we observe 2.4x faster when we would expect about 3-4x just from basic algebra and geometry. That means something may actually be reducing the gradient, transporting energy away from the poles.
(Score: 0) by Anonymous Coward on Friday October 11 2019, @09:01PM (1 child)
Yes. It's called the atmosphere and the ocean.
(Score: 0) by Anonymous Coward on Friday October 11 2019, @10:07PM
The parent apparently thinks energy was being (net) transported to the poles via the atmosphere and oceans. This indicates the opposite is happening (or some other assumption is wrong, eg CO2 is not actually well-mixed).
(Score: 1) by khallow on Saturday October 12 2019, @03:13AM