One of the greatest cold waves in recent decades struck with a ferocious vengeance during January 1985.
The true significance of the above sea level pressure analysis will be highlighted below, as this set the January 1985 arctic outbreak apart from more recent extreme cold events.
Anomalously warm conditions dominated December 1984, especially the second half of the month, through Christmas up to the beginning of the New Year.
A slightly positive North Atlantic Oscillation and a weakly positive Arctic Oscillation ( 0.446 index for December ) did not tell the full story during this ENSO neutral winter with its negative phased Quasi-biennial Oscillation ( QBO ).
A major mid-winter warming in the stratosphere, typically called a Sudden Stratospheric Warming ( SSW ) developed during late December 1984 with a reversal of the flow field at 60 degrees North and 10 MB into early January 1985.
The World Meteorological Organization ( WMO ) classifies a major SSW event as one which reverses the zonal mean zonal wind from westerly to easterly at 60 degrees North latitude and 10 MB.
Although Wave 1 forcing had become significant by late November 1984, to initiate Polar Vortex perturbation, this weakened as Wave 2 forcing reached record strong levels into late December 1984.
Under favorable conditions planetary and gravity waves emanating from the troposphere penetrate into rarefied air of the stratosphere where they break, like ocean waves rolling into a beach and ”feeling” the frictional drag of the surface, to release their momentum and energy fluxes.
Reference Middle Atmospheric Dynamics by Andrews, Holton, Leovy., 1987 for addition information.
Temperatures high above the North Pole rapidly climbed to record warm levels by the beginning of January 1985 as this Sudden Stratospheric Warming ( SSW ) event weakened the Polar Vortex in the stratosphere.
While air temperatures fell back to below average at 10 MB above the North Pole before the end of January 1985, record warm conditions persisted lower down at 100 MB through February 1985 with stratospheric-tropospheric coupling as recently documented and highlighted by Judah Cohen.
While it may seem the “polar” opposite of what should be, when the Polar Vortex weakens it creates a more favorable setting for arctic air outbreaks into middle latitudes as this great swirling mass of brutal cold relaxes and no longer pulls everything zonally across the Northern Hemisphere.
As exemplified by this current 2017-18 winter, it does not take a major SSW event to impact the Polar Vortex and cause changes in middle latitude conditions. The odds of having a major SSW event increases during a -QBO winter, which is presently the case.
While impacts began being felt almost immediately after this SSW event occurred, with both colder conditions and frequent periods of frozen precipitation locally, it was not until January 18-19 with approach of a major arctic front that implications of what was coming became clear.
While the magnitude of the bitter cold is off the bottom of the Kelvin scale used on these reanalysis charts, they still are useful in showing where the core of the coldest air was centered. Right over the Mountain Empire!
Reported Minimum Temperatures ( In Degrees Fahrenheit )
-21 degrees Clintwood 1 W
-24 degrees Campus of UVA-Wise
-25 degrees *Town of Clintwood
-30 degrees **Mountain Lake Biological Station
-35 degrees ***High Chaparral Community
*Recorded by Paul D. Buchanan in the town of Clintwood at the previous official recording site for precipitation ( 1964-Jan 1988 ).
**The all-time coldest temperature officially recorded in Virginia at a designated National Weather Service Cooperative Station. The elevation was at 3984 feet with 7″ of snow depth.
***The coldest unofficial temperature reported in the High Knob Massif; although, it is likely that colder temps have occurred and will eventually be documented by the undergraduate research project ongoing at the University of Virginia’s College At Wise. Recording instruments were not in place at the summit level during this 1985 period, when air temperatures were almost certainly colder over a substantial snowpack.
The recorded air temperature fell from 20 degrees at Clintwood 1 W at 7:00 PM on January 19 down to -15 degrees below zero by the morning to mid-morning period of January 20:
-15 degree AM MIN on January 20
-6 degree PM MAX on January 20
-10 degrees at 7:00 PM on January 20
These were lower elevation ( 1560 feet above sea level ) readings, with temperatures being much colder at upper elevations above 3000 feet in the area.
The cold was enhanced by widespread snow cover, with a snowpack at upper elevations in the High Knob Massif.
Note 1985 precipitation totals are given in the far right column, and the following local stations can be added to that list:
1985 Total Precipitation
Appalachia Lake Water Plant 43.88″
City of Norton Water Plant 49.85″ ( M )
( M ) – Indicates missing moisture in snowfall.
Precipitation data for the City of Norton has been found back to January 1983, so Norton was not recognized in 1985 as being the wettest town or city in Virginia as that fact had not yet been established back then.
However, by comparison of totals during 1985 with Norton ( which had missing data in snowfall using a small 4″-diameter NWS style gauge ) it can be seen that only time would be required.
While recorded MINS were impressive, this literally told only part of the story which separated this 1985 outbreak from more recent extreme cold.
Both from personal experience, and from ”raw” data, what really made the January 1985 outbreak one of the greatest within recent decades was WIND and barbaric Wind CHILL.
This was not the type of cold experienced most recently during the month of February 2015 when the official MIN dropped to a brutal -23 F degrees below zero in Clintwood, and very likely to below -30 degrees within high valleys of the High Knob high country where snow depth was 3 to 4 feet deep! The UVA-Wise collection of high resolution data just missed an opportunity to rewrite the known, or recorded, temperature climatology of Virginia in Feb 2015.
The brutal cold of February 2015 was biased toward the mountain valleys, where cold air drainage and radiational cooling over a deep snowpack was the driving force directly beneath High Pressure with light winds and clear skies.
The cold in January 1985, by contrast, occurred on WNW- NW upslope flow and strong winds such that clouds and upslope snow showers continued which biased the coldest conditions to upslope locations at upper elevations. That is why the High Chaparral community, at 3300 feet, reported the lowest local temperature even through summit level readings were likely colder above 4000 feet. Certainly, when factoring in strong winds, wind chill values were barbaric with -40 to -70+ below zero readings which are rarely ever experienced so far south in latitude.
#The old wind chill index used in the 1980s would have generated even lower chill values, with above values based upon the current wind chill index.
It should be noted that while arctic air masses are often stratified with the coldest air near the surface, in the low levels of the troposphere, that when orographic forcing is significant it can drive air upslope with adiabatic cooling occurring as air expands during forced lift ( significantly warmer air can then exist above the mountain tops, with inversional conditions ). In this case the arctic mass was relatively deep in vertical extent; although, no doubt with some stratification due to its density.
Surface temperatures can become colder than the 850 MB air due to such a process, as it can when light winds and clear skies set up ideal cold air drainage and radiational cooling like observed most recently during the extreme cold of February 2015. Multiple ways, especially in the mountains, to get air colder than incoming values indicate on any specific isobaric level ( e.g., 850 MB ).