Cold wave over the Eurasian Continent in December 201228 December 2012
Tokyo Climate Center, Japan Meteorological Agency
1. Overview
Since the end of November 2012, the Eurasian continent from northern East Asia toWestern Russia has experienced significantly lower-than-normal temperatures due tostrong cold-air inflow.

2. Climate conditions
Temperatures have been more than 6°C below normal from Central Siberia tonortheastern China since the end of November. The influence of cold air has extended
to Central Asia and Western Russia (Table 1 and Figure 1). Figure 2 shows dailytemperatures at major meteorological stations in affected countries.

Table 1 Weekly extreme low temperature events
PeriodAreasEvents
28 Nov. –Northeastern China
Daily minimum temperature was below
4 Dec.
-25°C on 3 Dec. at Tailai, China.
5 – 11 Dec. From around Lake Baikal to Daily minimum temperature was below
western Japan-24°C on 8 Dec. at Shenyang, China.
12 – 18 Dec. Fromsouthern
Central Daily minimum temperature was below
Siberia to around the -40°C on 15 and 17 Dec. at Astana,Caspian Sea
Kazakhstan.
19 – 25 Dec. From northeastern China to Daily minimum temperature was below
western Russia-25°C on 24 Dec. at Moscow, Russia.

3. Characteristics of atmospheric circulations
Since mid-December, many areas over Eurasia have experienced significantly low
temperatures due to the expansion of the Siberian High toward northwestern Russia,
which has brought cold air mass over southern Siberia into Central Asia to westernRussia.
In December, the jet stream tended to meander southward over East Asia and cold
air over the high-latitude areas frequently moved in. In the latter half of the month, theenhanced Siberian High contributed to strong cold-air inflow over the area (Figure 3).

28 Nov. – 4 Dec.
cdbabababa5 Dec. – 11 Dec.
cd12 Dec. – 18 Dec.
cd19 Dec. – 25 Dec.
cdFigure 1 Weekly temperature anomalies in the Northern Hemisphere from 28 November
2012 (Unit: °C, Based on SYNOP reports)
Daily temperature data at (a) Ulaanbaatar (Mongolia), (b) Astana (Kazakhstan), (c) Mos cow(Russia) and (d) Kiev (Ukraine) on the maps are shown in Figure 2.

010(a)Ulaanbaatar (Mongolia)

5-50Temperature （℃）-15-20-25-30

5-3515-Nov

22-Nov

6-Dec

13-DecTemperature （℃）-5平均気温最高気温
最低気温(b)Astana (Kazakhstan)-5Temperature （℃）

29-Nov-15-25-5-10-15-20-25(b)Astana (Kazakhstan)-3015-Nov

20-Dec20

平均気温平年値

15-1522-Nov

平均気温

29-Nov

6-Dec

最高気温

13-Dec

最低気温

20-Dec
平均気温平年値(d)Kiev (Ukraine)

10Temperature （℃）

Temperature （℃）-105(c)Moscow (Russia)-25-35-35

50-5-10-15-4515-Nov

22-Nov

-45
6-Dec
11/15

29-NovMean Temperature
Minimum Temperature-20

13-Dec11/2220-Dec
11/29

Maximum Temperature
Mean Temperature
Normal of Mean Temperature

Minimum Temperature

22-Nov 29-Nov
12/6 15-Nov
12/13
12/20

6-Dec

13-Dec

平均気温
最高気温
最低気温
MaximumTemperature
Normal of Mean Temperature

20-Dec
平均気温平年値

Figure 2 Daily maximum, mean and minimum temperatures (°C) at four stations from 15
November to 25 December 2012 (Based on SYNOP reports)

HighSignificantly
Cold air mass℃

Figure 3 Sea level pressure and surface air temperature (11 – 24 December 2012)
The contours indicate sea level pressure (hPa), and the cold shading denotes 2 m temperature(°C).