Snow related to shallow depression
during a
two week cold wave
Synopsis: at 500 hPa a ridge stretching from the Açores
towards the Norwegian Sea and a trough extending from the Baltic States
towards the Mediterranean Sea. Our area in a NE'ly flow of cold polar
maritime air in which in the lower levels a small low developed over the
southern Northsea and via the coastlines of the Low Countries towards
northern France migrated. It resulted in the afternoon and evening in
light to moderate falls of snow with in Belgium an accumation of 1 to 5
cm. It did occur in a two week cold wave, the longest since 1941, and
the frost led to massive
formation of ice. Pictures taken at Steenokkerzeel, Kampenhout &
Hofstade (central Belgium). Hours in local time (CET).
Surface analysis of February 3 2012 at 1300 CET. Small low over
northwest Hollland moving southwards. (Source chart: Belgocontrol)
Surface analysis of February 3 2012 at 1900 CET. Small low now over
western Belgium. (Source chart: metoffice.gov.uk)
Loop of 12 surface analyses of February 3 2012 between 1000-2100 CET
with the weather plots showing the movement of a shallow depression with
a pressure of 1033 hPa ! (Source: meteocentre.com)
Upper air analysis 500 hPa of February 3 2012 at 1300 CET. A cold pool
over the Baltic States extending to the Mediterranean resorts and a
ridge near the United Kingdom resulting overhead in a NNE'ly flow. (Source chart: DWD via wetter3)
Upper air analysis 850 hPa of February 3 2012 at 1300 CET. In a NNE'ly
flow, the isotherm of minus 11 was overhead. (Source chart: DWD via wetter3)
Loop of forecasted soundings for Brussels of February 3 2012 between
0830-1900 CET. At all levels the temperature remained negative with from
late afternoon onwards a saturated layer between almost surface and 700
hPa. (Source: RASP)
Another loop of forecasted soundings for Brussels of February 3 2012
between 1000-2200 CET. (Source: weatheronline.co.uk)
Forecasted vertical profile and surface temperature for Brussels of
February 2 2012 from
1200 UTC (=1300 CET) and the following 48 hours. Legend of upper map: green-brown-white
is humidity in steps of 10% with darkest green being 90% or more, wind
in kt, temperatures each 5°C. From 1200 UTC of February 3 onwards,
increasing clouds, first at medium levels later also lower levels. (Source: Belgocontrol)
Corresponding precipitation and surface winds. In
reality, wind didn't veer but backed (see METARS below). The amount of
liquid water that fell was 1,2 mm, but the snow flakes contained such a
lot of air resulting in an accumulation in cm of factor 2 to 4. (Source: Belgocontrol)
03/02/2012 1445-1645 CET. Satellite loop in the visual channel. Cloud
belt over Holland moving into Belgium. (Source sat picture: Eumetsat via
Sat24.com)
03/02/2012 1400 CET. Satellite picture (infra-red) with in overlay
the precipitation type. (Source sat picture: DWD)
Radar loop (reflectivity in dBZ) of
February 3 2012 between 1130-2140 CET. Green colors represents moderate
snow, blue colors is light snow. (Source radar picture: Belgocontrol).
Some metars (hours in UTC) of some Belgian airports / airfields. Translation: copy paste each obs via
metar-decoder
EBBE 031125Z
VRB01KT 9999 FEW070 BKN090 BKN120 M06/M15 Q1037 BLU BLU
EBBE 031225Z VRB01KT 9999 FEW060 BKN100 BKN115
M05/M15 Q1037 BLU BLU
EBBE 031325Z VRB03KT 9999 SCT036 BKN050 M05/M15
Q1036 BLU BLU
EBBE 031338Z 23004KT 9999 FEW035 BKN040 M05/M14
Q1035 BLU WHT TEMPO GRN
EBBE 031351Z VRB03KT 9999 -SN BKN040 M05/M14 Q1035
BLU WHT TEMPO GRN
EBBE 031359Z 22004KT 5000 -SN FEW010 SCT037 BKN042
M05/M14 Q1035 WHT GRN TEMPO YLO
EBBE 031402Z 23004KT 5000 -SN FEW010 SCT032 BKN038
M05/M13 Q1035 WHT GRN TEMPO YLO
EBBE 031407Z 21005KT 4000 -SN SCT013 BKN030
M05/M13 Q1035 GRN GRN TEMPO YLO
EBBE 031410Z 20005KT 2000 -SN SCT013 BKN030 M06/M12 Q1035 YLO YLO TEMPO
AMB
EBBE 031425Z 21005KT 2000 -SN SCT010 BKN025 M06/M11 Q1035 GRN YLO TEMPO
AMB
EBBE 031433Z 19005KT 2400 SN FEW005 BKN016 M06/M10 Q1035 YLO FCST CANCEL
EBBE 031440Z AUTO 19006KT 1500 -SN VV008 M06/M10 Q1035 AMB
EBBE 031456Z AUTO 20005KT 0700 SN VV005 M07/M09 Q1035 RED
EBBE 031520Z AUTO 19005KT 0800 SN VV006 M07/M08
Q1035 AMB
EBBE 031525Z AUTO 19005KT 1200 SN VV009 M07/M08
Q1035 AMB
EBBE 031616Z AUTO 18004KT //// -SN VV009 M07/M08
Q1035
EBBE 031625Z AUTO 17004KT //// -SN VV008 M07/M08
Q1035
EBBE 031725Z AUTO VRB03KT 1500 -SN VV012 M07/M08 Q1036 AMB
EBBE 031728Z AUTO VRB03KT 1700 -SN VV013 M07/M08 Q1036 YLO
EBBE 031749Z AUTO VRB03KT 3700 -SN FEW024 BKN036
M07/M08 Q1036 GRN
EBBE 031756Z AUTO VRB03KT 3600 -SN FEW027 OVC036
M07/M08 Q1036 YLO
EBBE 031802Z AUTO VRB03KT 3800 -SN OVC036 M07/M08
Q1036 GRN
EBBE 031825Z AUTO VRB03KT 4500 -SN BKN036 OVC041
M07/M08 Q1036 GRN
EBBE 031841Z AUTO VRB03KT 5000 -SN BKN040 BKN046
M07/M08 Q1036 WHT
EBBE 031907Z AUTO VRB03KT 4800 -SN OVC046 M08/M09 Q1036 GRN
EBBE 031913Z AUTO 12004KT 5000 -SN OVC046 M08/M09 Q1036 WHT
EBBE 031919Z AUTO 12005KT 4500 -SN OVC045 M08/M09
Q1036 GRN
EBBE 031925Z AUTO 11004KT 4100 -SN BKN044 OVC050
M08/M09 Q1036 GRN
EBBE 031933Z AUTO 10004KT 5000 -SN BKN044 OVC050 M08/M09 Q1036 WHT
EBBE 032025Z AUTO VRB03KT 6000 -SN FEW048 M09/M10 Q1037 WHT
EBBE 032028Z AUTO VRB02KT 6000 -SG SCT048 M09/M10 Q1037 WHT
EBBE 032102Z AUTO VRB03KT 4800 BR FEW049 M11/M11
Q1037 GRN
04/02/2012. Snow height in cm taken from the synops of 0600 UTC the next
morning.
04/02/2012. Minimum temperature in degrees Celcius taken from the synop
of 0600 UTC the next morning, with the winner being Retie -18,4°C.
04/02/2012. Temperature histogram in degrees Celcius in local time (CET)
taken from an automatic station at Kampenhout with a minimal value of
-16,6°C at 0640 CET. This was recorded in a closed temperature cabin, in
open air even -18,4°C was measured, the coldest moment since January 7
1985 (with on that morning even -21°C).
Temperature histogram in degrees Celcius in local time (CET)
taken from an automatic station at Kampenhout. Starting date is January
27 2012 and ending date is February 14 2012. On January 29, at 1613 CET,
air temperature went below 0°C and it lasted till February 13 0819 CET,
making it 328 hrs and 6 minutes of continuous frost. Undoubtedly,
February 4 was the coldest day. In this frost period 1,2 mm of water
fell on February 3, corresponding (briefly) with a snow height of 5 cm.
04/02/2012. This satellite picture shows clearly where in Europe a snow
deposit was present. (Source satpicture: NOAA
and University of Bern)
04/02/2012. A zoom over the Low Countries. The red "K" is indicating
where the pictures below were taken. (Source: Image courtesy of MODIS Rapid Response Project at
NASA/GSFC)
03/02/2012. Snow height in cm taken from observations of weather
amateurs just after the snow had fallen. Source map: hetweeractueel.nl
03/02/2012 1717 (Steenokkerzeel). Proof of the date.
03/02/2012 1626 (Steenokkerzeel). Bit before, situation on the road when
the snow fell.
03/02/2012 1725 (Steenokkerzeel). After most of the snow fell, heading to Kampenhout.
03/02/2012 1725 (Steenokkerzeel). Saying the tower goodbye.
03/02/2012 1732 (Steenokkerzeel). The main road heading to Kampenhout.
03/02/2012 1748 (Kampenhout). At home, on the table proof of 5 cm
accumuation.
04/02/2012 1031 (Kampenhout). Next day, a misty start of the day.
04/02/2012 1303 (Kampenhout). From noon the sun came out.
04/02/2012 1309. Small sight seeing tour at Kampenhout.
04/02/2012 1310. Rime.
04/02/2012 1311. More rime.
04/02/2012 1312.
04/02/2012 1317.
04/02/2012 1337. Small frozen lake.
10/02/2012 1346. Six days later, after 12 days of frost, situation at
het kanaal Mechelen-Leuven.
10/02/2012 1350. Some gulls taking a nap on the ice.
10/02/2012 1357. Some swans...
10/02/2012 1433. Ice breakers were already before in action, thus barges
could still be seen at het kanaal Mechelen-Leuven.
10/02/2012 1617. Closer inspection, with behind the first barge another
one, presumable with a somewhat weaker underside taking no risks at all, at het kanaal Mechelen-Leuven.
10/02/2012 1715 (Hofstade). This large lake was also completely frozen,
although no ice skating was allowed.
