OK, it's time to talk things Arctic polar vortex ...
... as in the wintertime Arctic polar vortex and how it is poised to make a rather dramatic visit to the United States.
The above picture is a map of plot of 500 hecto-Pascal (hPa) -- equivalent to 500-millibars (mb) -- they geopotential height anomalies (discussed below) as produced by the 0Z January 3, 2014 GFS model but prettied up by an operation called WeatherBELL Analytics and posted on the Capital Weather Gang's January 3rd, 2014 entry (link embedded): An astonishing, dangerous cold snap is about to descend on the U.S.
Above: 12Z Jan. 4, 2014 GFS showing 1000mb - 500mb thicknesses, MSLP, and 6-hr precip across eastern and central North America valid at hour 96 / 9Z (4AM EST) January 7th, 2014. Note the closed 486 dkm thickness contour near Lake Superior. See below for explanation of what this means.
Above: 12Z Jan. 4, 2014 GFS showing 500mb vorticity and geopotential heights across the U.S. Lower 48 and Canada also valid at hour 96 / 9Z (4AM EST) January 7th, 2014. This too shows the central closed 486 dkm geopotential height contour.
These three plots show that the wintertime Arctic (polar) vortex has slid COMPLETELY out of the Arctic region and is centered over parts of the Lower 48 U.S.
Now to clarify, the wintertime Arctic (polar) vortex is "normally" located over the North Pole but "sloshes" and undulates around in response to the atmospheric (both tropospheric and stratospheric) dynamics as manifested in motions of the get stream and position of highs and lows (and often stated in terms of "positive" and "negative" Arctic and North Atlantic oscillatory phases).
A negative phase Arctic Oscillation (AO) showing 500mb geopotential height anomalies (in dekameters) from December 2009 versus 1968 - 1996 climatology. This is a reanalysis of data, not a real-time measurement.
A typical positive phase Arctic Oscillation (AO) showing 500mb geopotential height anomalies (in dekameters) from January 1993 versus 1968 - 1996 climatology. This is a reanalysis of data, not a real-time measurement.
Geopotential height refers to the altitude of pressure surfaces, in particular, the 500mb surface (considered the half way mark of the atmosphere in terms of pressure). It is measured in dekameters, so "540 thickness" means a 500-mb pressure surface that is 5,400 meters above the 1000-mb surface (i.e., the ground at sea level). The lower the thicknesses, the colder it is. The plots above show the dkm anomalies while the lead image shows a standard deviation anomaly.
As an aside, the Antarctic wintertime polar vortex is far more stationary than the Arctic wintertime polar vortex because Antarctica is a far more isolated and extreme environment. Indeed, the reason there has been for decades a seasonal ozone hole over the Antarctic in response to manmade CFCs and not over the Arctic is simply because of how much colder it gets in the Antarctic and the resulting different chemistry at play when sunlight returns in the austral spring.)
Left: Ozone loss shown in this old TOMS instrument image of ozone concentrations (in Dobson Units) inside the Antarctic vortex in October 1991 at the start of the austral spring.
Anyway, this is the second and stronger of the two Arctic blasts this first week of January 2014. The first one is now ebbing, though not before it got plenty cold. Even here in the D.C. area it got down this morning to 17F at KDCA, 8F at KIAD, and 6F at KBWI.
The 12Z Jan. 4, 2014 GFS showing 850mb temperatures, 6-hour precipitation, and mean sea level pressure (MSLP) valid at hour 69 / 9Z (4AM EST) January 7, 2014. Note the closed -30C isotherm over West Virginia. This is an 850mb temp or approximately 5,000 above sea level.
News of the impending second Arctic blast already entered mass media reports such as this AP one (link embedded): 'Polar vortex' to blast frigid air over much of US. This is good if it helps people prepare for the brief but (as the current Sterling LWX discussion puts it) "brutally and dangerously cold" Arctic onslaught across much of the eastern half of the United States.
It is also good even if millions of Americans get confused by the term "polar vortex" and think it means the Second Coming is nigh and global warming is a "hoax."
To the latter point, I dared not look at the comment section to the linked story. There are presently nearly 4,000 comments.
Yes, Middle Americans, get thee to thy nearest Walmart (or Target) and buy thyselves appropriate Bangladeshi manufactured winter gear - coats, sweaters, thermals (yes, thermal undergarments), gloves, and woolly hats.
Now to be clear, this Arctic blast is NOT "proof of global cooling," no matter what is bellowed inside the entertainment and disinformation bubble of Fox News / talk radio / and the internets.
And now a word from our sponsors: Buy Gold Bullion NOW! Dollar collapse and hyper-inflation imminent!
And, no, it's not because Obama secretly "manufactured" the cold air in Hawaii as part of his dastardly plot to redirect attention from his Kenyan birth because he is a secret radical Muslim atheist (huh?) intent on fostering a "radical climate change scientific activist agenda" on you (now how exactly does that work ...?)
Just get some warm clothes and let's call it a day.
But I do have to ask: Where's James Inhofe's igloo? I think we left it outside behind the gay bar that no one in his family has visited for over 200 years.
As for here in the Metro D.C. and Metro, Baltimore areas, it may get down 0F even in the close-in suburbs Tuesday morning and highs won't get much above 15F even in the District. The outer suburbs may very well go below zero. This would include Dulles Airport.
It will be the coldest since Jan. 19 - 21, 1994 -- or almost 20 years to the week.
Here are the daily records to consider for the period in question (as provided by Sterling LWX):
January 7th record minimum temperatures:
KDCA: 5F (1884)
KBWI: 8F (1988)
KIAD: 8F (1988)
January 7th record low maximum temperatures:
KDCA: 18F (1878)
KBWI: 22F (1878 / 1988 / 1996)
KIAD: 21F (1988 / 1996)
All six of these records may be broken.
For January 8th, the record minimum temperatures are:
KDCA: 0F (1878) (pre-National record)
KBWI: 4F (1970)
KIAD: -4F (1970)
Probably only the KBWI record has a chance of being tied / broken.
Oh, and the wind chills are going to be brutal for a time.
Wind chill readings in Fahrenheit for the Sterling (LWX) county warning area (CWA) including Metro D.C. and Metro Baltimore based on the 0Z Jan. 4, 2014 GFS valid at hour 84 / 12Z (7AM EST) January 7, 2014 (Tuesday morning). There are wind chills in West Virginia and Pennsylvania that are -30F to -45F.
Changing subjects ...
I came across this chart in that purports to graphical show the liquor preference -- that is, spirits and wines -- of Americans based on their political affiliation and likelihood of actually voting.
It is based on a sample of just under 50,000 people as was put together using consumer data from GFK MRI and analyzed by Jennifer Dube of National Media Research Planning and Placement. It appears in this GovBeat blog entry on The Washington Post's online site from December 31, 2013.
OK, one my entry to follow (my jukebox Saturday night entry, posted early).