If the planet is warming -- how can it be so damn cold out there, in the winter?
Well the connections are complex, but they are not unfathomable (to science and physics literates.)
'Polar vortex' to blast frigid air over much of US
by Carson Walker, Associated Press; boston.com -- Jan 3, 2014
SIOUX FALLS, S.D. (AP) — The weather warnings are dire: Life threatening wind chills. Historic cold outbreak.
Winter is normally cold, but starting Sunday tundra-like temperatures are poised to deliver a rare and potentially dangerous sledgehammer blow to much of the Midwest, driving temperatures so far below zero that records will shatter.
One reason? A "polar vortex," as one meteorologist calls it, which will send cold air piled up at the North Pole down to the U.S., funneling it as far south as the Gulf Coast.
[...]
Here's what our current mid-latitude Jet Stream looks likes:
Weather Model -- Global Jet Stream Wind and 250 mb Pressure (animated loop)
larger
Notice how it has those big 'loopy waves' (aka high-amplitude Rossby Waves). It is the big swoop southward that is ushering in the current frigid polar air.
Arctic Outbreak: When the North Pole Came to Ohio
by Andrew Freedman, climatecentral.org -- Jan 2, 2014
[...]
At the peak of the Arctic outbreak, temperatures may be between 20°F and 40°F below average in large parts of the continental U.S., with dangerous wind chills affecting cities like Minneapolis, Chicago, Cleveland, St. Louis, Washington, D.C., New York, and Boston. The U.S. will have the dubious distinction of experiencing the largest cold temperature anomalies of any land area in the Northern Hemisphere during the height of the biting cold.
[...]
The cause of the Arctic outbreak can be traced to northeastern Canada and Greenland, where an area of high pressure and relatively mild temperatures is set to block the eastward progression of weather systems, like an offensive lineman protecting the quarterback from the other team.
The atmospheric blocking is forcing a section of the polar vortex to break off and move south, into the U.S. The polar vortex is an area of cold low pressure that typically circulates around the Arctic during the winter, spreading tentacles of cold southward into Europe, Asia, and North America at times. Except this time, it’s not a small section of the vortex, but what one forecaster, Ryan Maue of WeatherBELL Analytics, called “more like the whole enchilada” in a Twitter conversation on Thursday.
[...]
Computer model projection showing the location of the polar vortex (outlined in orange) and areas of below average temperatures (green and blue) and above average temperatures (orange and red), as indicated by the height of atmospheric pressure levels. The annotations show the cold temperature anomaly in the U.S. and mild anomalies across the Arctic. Credit: WeatherBELL Analytics.
The Arctic Vortex is supposed to stay in the Arctic. It is supposed to form a tight circle, racing around the pole. It is not supposed to branch out and send frigid polar air to the temperate mid-latitudes. At least not on a 'regular basis'.
But then again, unusual stratospheric warming in the Arctic, is not supposed to be breaking that Polar Vortex up into smaller pieces, either.
Just because it's out of sight, doesn't mean it should be out of mind.
[Note: most of what follows is analysis of last winter's arctic events -- which are looking remarkably similar to this winter's arctic events.]
Who says all that record-breaking Arctic Ice Melt really doesn't matter?
Certainly not well informed meteorologists, because they say it kind of does ...
Stratospheric Phenomenon Is Bringing Frigid Cold to U.S
by Andrew Freedman, climatecentral.org -- Jan 21, 2013
[...]
Sudden stratospheric warming events take place in about half of all Northern Hemisphere winters, and they have been occurring with increasing frequency during the past decade, possibly related to the loss of Arctic sea ice due to global warming. Arctic sea ice declined to its smallest extent on record in September 2012.
[...]
Sudden stratospheric warming events occur when large atmospheric waves, known as Rossby waves, extend beyond the troposphere where most weather occurs, and into the stratosphere. This vertical transport of energy can set a complex process into motion that leads to the breakdown of the high altitude cold low pressure area that typically spins above the North Pole during the winter, which is known as the polar vortex.
The polar vortex plays a major role in determining how much Arctic air spills southward toward the mid-latitudes. When there is a strong polar vortex, cold air tends to stay bottled up in the Arctic. However, when the vortex weakens or is disrupted, like a spinning top that suddenly starts wobbling, it can cause polar air masses to surge south, while the Arctic experiences milder-than-average temperatures.
[...]
Ok, what's a Rossby Wave and how does global warming effect them? (If you have a low threshold for watching videos, this is the best one of the bunch, imo.)
Jennifer Francis - Understanding the Jetstream (and Rossby Waves)
link to clip
Published on Feb 26, 2013 -- by rustneversleeps3
A short review of how the jetstream and Rossby waves work, and some emerging indications that the dynamics may be changing in a warming world.
So, what's a Polar Vortex, and what happens when it get displaced, by one of those unusually TALL bubbles of
relatively warm atmosphere, surging northward?
Polar Vortex
link to clip
Published on Jan 18, 2013 -- WTHI-TV
Here's an meteorological map analysis of various Arctic Vortex splits, what causes them, and what they lead to (... record cold in the Mid-Latitudes).
Stratospheric Warming by The SI Weather
link to clip
Uploaded on Dec 16, 2011 -- TheSIWeather
Here's one meteorological speaker, who's a bit eccentric, but does seem to have a good grasp on Stratospheric Warming events -- going Polar, anyways.
Extreme Event (Vortex Formation and Displacement)
link to clip
Published on Jan 18, 2013 -- TurtleIslandNewsDaily.info
Sudden Stratospheric Warming Split the Polar Vortex in Two.
the polar vortex was intact at 50 millibars(height in m) on January 1 to 3.
the polar vortex had broken in two (50millibar heights in m) on January 10 to 13
Finally, here's a good old-fashioned
science satellite composite (it's a very short clip), that shows what happens when the Polar Vortex, gets nudged into going for 'a power walk'.
GMAO - GEOS-5 Stratospheric Sudden warming Event
link to clip
Published on Mar 4, 2013 -- Harold Saive
http://gmao.gsfc.nasa.gov/...
http://gmao.gsfc.nasa.gov/...
And finally here's
an updated 2014 Winter forecast, once again 'blaming that Polar Vortex' for 'deciding' to go meandering somewhere -- that we'd rather not see it go.
WRGX; wtvy.com -- January 4, 2014
Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Valid 12Z Sat Jan 04 2014 - 12Z Mon Jan 06 2014
[...]
Forecast models remain consistent in carrying the polar vortex into the northern tier of the U.S. while carrying it eastward in time.
Many locations may see their temperature readings drop to near record values.
[...]
Incredibly, it may feel as cold as -50 to -60 on Sunday night over sections of the north-central states with the frigid air remaining in place into early next week.
As the vortex shifts eastward, the polar air will begin to affect the Great Lakes and Ohio Valley with temperatures plummeting rapidly.
While the air mass will modify, temperatures will remain downright cold with the forecast high in Chicago, IL being only -11 on Monday.
A strong frontal boundary surging eastward ahead of the polar air mass will become rather active as it intercepts increasing amounts of low-level moisture.
[...]
If only those record-melting Arctic ice packs would stay in place and not keep warming up their supposed-to-be Arctic neighborhoods by exposing all that open sea water --
then maybe that Arctic Vortex might not have to 'go wobbling around like a wildly spinning top --
losing its fast-track momentum' ... at such an ever increasing rate.
But then again, Who needs stable Jet Streams anyways?
Certainly not farmers, not foresters, not ranchers; Certainly not suburban folks who hate all these crazy arctic deep freezes ... the ones who ask, "Why in the world, is it so damn cold, anyways?"
Now hopefully, you can tell them.
