Weather pictures & report of November 29 - December 4 2010

 

Cold wave after occluded front.


Synopsis: at 500 hPa sharpening upper trough crossed our area. Related occlusion produced some light snow and was followed by very cold continental air  introducing a 5 day cold wave. On December 1 milder air tried from the south to counter the cold spell which led to widespread snowfall. On December 4 another attack of the mild air was succesfull, is was briefly preceded by blowing snow.  All pictures were taken at Kampenhout (central Belgium), hours in local time (CET). 

 

Surface analysis of December 20 2009 at 0700 CET. Occluded frontal system entering the Low Countries and moving eastwards. It is followed by a trough line (Source chart: Belgocontrol)

 

Loop of 5 surface analyses (of 08, 09, 10, 12 and 13 CET) with weather plots showing the movement of the depression and associated wintry precipitation belt. (Source: meteocentre.com)

 

Upper air analysis 500 hPa of December 20 2009 at 1300 CET. Our region close to a cut-off low of which the axis of a trough crossed the Benelux. (Source chart: DWD via wetter3)

 

Loop of forecasted soundings for Brussels of December 20 2009 between 0830-1900 CET. Temperature from noon onwards at the bottom layer tempo slightly positive, but all above subzero values. Indication that the first precipitation is 100% under solid form, at the end (of the front) a wet component could be possible as well.

Furthermore: first part of the period passage front with temporary warmer air (= stable) at certain heights (= warm occlusion giving the appearance of a "nose" on the sounding). From 1300-1400 CET onwards the curve becomes steeper to the left (= unstable) as colder air is advected (due to passage upper trough). (Source: RASP)

 

Another loop of forecasted soundings for Brussels of December 20 2009 on a larger time scale between 0100-1900 CET. (Source: weatheronline.co.uk)

 

20/12/2009 0615-0800 CET. Satellite loop in the infra-red channel. The stratiform layer entering the Benelux. (Source sat picture: Eumetsat via Sat24.com)

 

20/12/2009 1130-1245 CET. Satellite loop in the visible channel. Layered stratiform cloudiness over the eastern parts of the Benelux. On the western side, besides low stratiform clouds, also indication of cumuliform cloudiness. Over the U.K. the cover of snow is clearly visible. (Source sat picture: Eumetsat via Sat24.com)

 

Radar loop (reflectivity in dBZ) of December 20 2009 between 0400-1555 CET. A rather huge precipitation belt crossing the area which is composed of two parts: the first one induced by an weakening upper front, the second active belt was the due to the occluding front. Afterwards, during the afternoon, on passage upper trough also some wintry showers. (Source radar picture: Belgocontrol)

 

Some metars (hours in UTC) of Brussels Airport (EBBR). Translation: copy paste each obs via metar-decoder

EBBR 200220Z 20014KT 9999 FEW016 M05/M10 Q1003 R57/090057 R02/090055 R07/720446 TEMPO 0800 SN BKN007
EBBR 200250Z 20015KT 9999 FEW016 M05/M09 Q1002 R57/090057 R02/090055 R07/720446 TEMPO 0800 SN BKN007
EBBR 200320Z 20017KT 7000 -SN SCT016 BKN024 M04/M09 Q1001 R57/090057 R02/090055 R07/720446 TEMPO 0800 SN BKN007
EBBR 200350Z 20015KT 4500 -SN SCT013 BKN016 M04/M08 Q1001 R57/090057 R02/090055 R07/720446 TEMPO 0800 SN BKN007
EBBR 200420Z 19017KT 3400 -SN SCT007 BKN011 M05/M08 Q1001 R57/090057 R02/090055 R07/720446 TEMPO 0800 SN BKN007
EBBR 200450Z 19017KT 9000 -SN SCT010 BKN047 M04/M08 Q1000 R57/090057 R02/090055 R07/720446 TEMPO 2500 -SN BKN007
EBBR 200520Z 19017KT 6000 -SN FEW010 BKN018 M04/M07 Q0999 R25///99// R20/590163R75/590162 TEMPO 2500 -SN BKN007
EBBR 200520Z 19017KT 6000 -SN FEW010 BKN018 M04/M07 Q0999 R25/99 R20/590163 R75/590162 TEMPO 2500 -SN BKN007
EBBR 200550Z 19017KT 7000 -SN FEW011 BKN036 M04/M07 Q0998 R25///99// R20/590163R75/590162 TEMPO 2500 -SN BKN007
EBBR 200550Z 19017KT 7000 -SN FEW011 BKN036 M04/M07 Q0998 R25/99 R20/590163 R75/590162 TEMPO 2500 -SN BKN007
EBBR 200620Z 19018KT 7000 -SN FEW009 BKN029 M04/M07 Q0997 R25///99// R20/590163R75/590162 TEMPO 2500 -SN BKN007
EBBR 200620Z 19018KT 7000 -SN FEW009 BKN029 M04/M07 Q0997 R25/99 R20/590163 R75/590162 TEMPO 2500 -SN BKN007
EBBR 200650Z 20016KT 2500 SN FEW009 BKN029 M04/M06 Q0997 R25///99// R20/590163 R75/590162 TEMPO BKN007
EBBR 200650Z 20016KT 2500 SN FEW009 BKN029 M04/M06 Q0997 R25/99 R20/590163 R75/590162 TEMPO BKN007
EBBR 200720Z 20015KT 2000 R25L/P1500N R25R/1300N R02/P1500N SN SCT003 BKN029 M04/M06 Q0997 R25/////// R20/290065 R75/710461 TEMPO 0500 SN BKN002
EBBR 200750Z 20015KT 0700 R25L/0900V1400D R25R/0350V0650D R02/0550VP1500D SN SCT000 BKN008 M04/M05 Q0996 R25/////// R20/490234 R75/490237 TEMPO 0500 SN BKN002
EBBR 200820Z 20017KT 0500 R25L/0550V0800U R25R/0325V0550U R02/0225N SN FZFG BKN000 BKN001 M04/M05 Q0996 R25/////// R20/490234 R75/490237 BECMG 3500 -SN BKN007
EBBR 200850Z 20014KT 0900 R25L/0700N R25R/0400V0650U R02/0125N SN FZFG BKN000 BKN003 M04/M05 Q0996 R25////// R20////// R75////// BECMG 3500 -SN BKN007
EBBR 200850Z 20014KT 0900 R25L/0750U R25R/0400V0650N R02/0125N SN FZFG BKN000 BKN003 M04/M05 Q0996 R25//99// R20//99// R75//99// BECMG 3500 -SN BKN007
EBBR 200920Z 20016KT 1700 R25L/1200N R25R/0900N R02/0150N SN SCT003 BKN006 M04/M06 Q0996 R25//99// R20//99// R75//99// BECMG 3500 -SN
EBBR 200950Z 21017KT 1700 R25L/1200N R25R/0800N R02/0175N SN FEW008 BKN010 M03/M05 Q0995 R25//99// R20//99// R75//99// BECMG 3500 -SN
EBBR 201020Z 21015KT 3500 R25L/P1500N R25R/1100N R02/0350V0750U -SN FEW008 BKN012 M03/M05 Q0995 RESN R25//99// R20//99// R75//99// NOSIG
EBBR 201050Z 21015KT 1100 R25L/1200N R25R/0800N R02/P1500N SNRA FEW008 BKN011 M02/M04 Q0995 R25//99// R20//99// R75//99// NOSIG
EBBR 201120Z 21015KT 5000 R25L/1100VP1500D R25R/0900V1300D R02/P1500N -SNRA FEW010 BKN019 M02/M04 Q0995 RESNRA R25//99// R20//99// R75//99// TEMPO 2500 SNRA BKN008
EBBR 201150Z 23012KT 9999 R25L/P1500N R25R/1400U R02/P1500N BKN010 M01/M03 Q0995 R25//99// R20//99// R75//99// TEMPO 2500 SNRA BKN008
EBBR 201220Z 23013KT 3000 R25L/P1500N R25R/1300N R02/P1500N -SNRA BKN007 M01/M03 Q0995 R25//99// R20//99// R75//99// TEMPO 2500 SNRA
EBBR 201250Z 24014KT 2000 R25L/0900VP1500U R25R/0550V0800N R02/0550V0800U SHSNRA FEW006 BKN013 M00/M02 Q0995 R25//99// R20//99// R75//99// BECMG 6000 NSW
EBBR 201320Z 24010KT 9000 R25L/P1500N R25R/1100U R02/P1500N FEW006 BKN014 M00/M02 Q0995 RESHSNRA R25//99// R20//99// R75//99// TEMPO 4500 -SHSNRA
EBBR 201350Z 26013KT 2600 R25L/P1500N R25R/1000N R02/P1500N -SHSNRA FEW003 BKN010 00/M01 Q0995 R25//99// R20//99// R75//99// BECMG 9999 NSW
EBBR 201420Z 26014KT 9999 FEW027 01/M02 Q0996 R25////// R20////// R75/614078 NOSIG
EBBR 201450Z 26014KT CAVOK 01/M03 Q0996 R25////// R20////// R75/614078 NOSIG
 

 

Time lapse of webcam images between 0832-1549 CET showing how the (blowing) snow added 8 cm to the already present 10 cm. The largest snowflakes did occur on the wintry showers.

 

The Aqua satellite giving a view about the snow deposit over Northwest-Europe. My location at red "K" where some pics were taken, see below. (Source: Image courtesy of MODIS Rapid Response Project at NASA/GSFC)

 

20/12/2009 0914 W. Wind & snow, the most intense part was passing by with poor visibilities.

 

20/12/2009 0915 WNW.

 

20/12/2009 0918 S.

 

20/12/2009 1046. Afterwards, a walk in "Den Dreef".

 

20/12/2009 1049. Opposite view.

 

20/12/2009 1052 NE. Due to the wind, the snow cover on the trees was unexpected tumbling down.

 

20/12/2009 1125. This is how 18 cm of snow looks like. It was almost 28 years ago to find such amount.

 

20/12/2009 1343 W. After a brief dry spell, a couple snow showers turned up.

 

20/12/2009 1452. After these showers, out again for a walk in the park.

 

20/12/2009 1500. Somewhere below is a (frozen) water pool.

 

20/12/2009 1526 SW.

 

20/12/2009 1636 SSW. Sun was setting.

 

20/12/2009 1638 NE. Opposite view, nice red colours.

 

20/12/2009 1639 SW. Final salute to this thick pack of snow. In the pouring rain a wet cover of 3 cm was left on Xmas day, thus making it officially a white Xmas, but surely we had another dream about it.

 

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