Weather pictures & report of December 4 2010

 

Snow related to occlusion and warm front ending a five day cold wave.


Synopsis: at 500 hPa a sharpening Atlantic trough veered over the Low Countries the airflow to the southwest with milder air on its way. A first occluded front gave 1 cm of fresh snow, a second one (warm front) was temporary preceded by blowing snow adding another 3 cm giving a  maximum snow cover of 8 cm at my location (Kampenhout). All pictures were taken at Steenokkerzeel (5 km from Kampenhout). Hours in local time (CET). 

 

Surface analysis of December 4 2010 at 1300 CET. A first occluded frontal system moved in from the SW. (Source chart: Belgocontrol)

 

Surface analysis of December 4 2010 at 1900 CET. During the evening a warm front gave prefrontal still some intense snow, but postfrontal became rapid rain making an end of the snow story in Low and Mid Belgium. (Source chart: Belgocontrol)

 

Loop of 14 surface analyses of December 4 between 1000-2300 CET with the weather plots. (Source: meteocentre.com)

 

Upper air analysis 500 hPa of December 4 2010 at 1300 CET. Sharpening trough over the Atlantic Ocean with over the Low Countries a W'ly flow in which another short wave relaxing trough is approaching from the U.K. (Source chart: DWD via wetter3)

 

Upper air analysis 850 hPa of December 4 2010 at 1300 CET. In a SW'ly flow, the minus 8 degrees is retreating over Germany and over northwest France the minus 1 degrees is approaching. (Source chart: DWD via wetter3)

 

Loop of forecasted soundings for Brussels of December 4 2010 between 0830-1900 CET. Temperature over the entire layer is negative remained just negative when the first front crossed, but became positive from 1800-1900 onwards in layer 300-1000 m introducing liquid precipitation with risk of temporary freezing. (Source: RASP)

 

Another loop of forecasted soundings for Brussels between December 4 1000 CET and December 5 1300 CET. Layer SFC till 1500m became positive from 2000 CET onwards. It approached again the freezing level from 0600 CET onwards, but only some wet snow was observed at Brussels. On the other hand snow did fall the entire day in regions with altitude of 100 m or higher giving 5 tot 20 cm. (Source: weatheronline.co.uk)

 

04/12/2010 1000-1545 CET. Satellite loop in the visual channel. Thick cloudiness related to the occluded front and waving warm-cold front behind. Also notifying is the snow cover over 3/4 of France, Germany, Swiss and Austria. (Source sat picture: Eumetsat via Belgocontrol)

 

04/12/2010 1830-0000 CET. Satellite loop in the infra-red channel. Massive cloudiness related to the waving frontal system that led to the thaw in Low and Mid Belgium. (Source sat picture: Eumetsat via Sat24.com)

 

Radar loop (reflectivity in dBZ) between December 4 1000 CET and December 5 0100 CET. Around noon a quite intensive precipitation of the occluded front giving temporary moderate falls of snow (see pictures taken at Steenokkerzeel below). During the evening followed by another intensive precipitation belt of the warm (thaw) front. Transformation solid to liquid form did occur at Brussels around 1930Z. (Source radar picture: Belgocontrol)

 

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


EBBR 040950Z 19018KT 9999 SCT040 M01/M05 Q1012 R25L/290063 R20/290057 R25R/290055 TEMPO 2500 -SN BKN008
EBBR 041020Z 19018KT 9999 SCT038 M01/M05 Q1012 R25L/290063 R20/290057 R25R/290055 TEMPO 2500 -SN BKN008
EBBR 041050Z 19018G28KT 9999 SCT033 M01/M05 Q1012 R25L/290063 R20/290057 R25R/290055 TEMPO 2500 -SN BKN008
EBBR 041120Z 19018KT 4000 -SN FEW015 BKN030 M01/M04 Q1011 R25L/290063 R20/290057 R25R/290055 TEMPO 2500 -SN BKN008
EBBR 041150Z 19019KT 1200 R25L/1100VP2000D R25R/1000VP2000D R02/1200VP2000D SN FEW004 BKN007 M01/M03 Q1011 R25L/290063 R20/290057 R25R/290055 TEMPO 0800 SN BKN004
EBBR 041220Z 19019KT 2500 -SN FEW006 BKN012 M01/M03 Q1011 R25L/290063 R20/290057 R25R/290055 BECMG 4000
EBBR 041250Z 20017KT 4000 -SN FEW006 BKN012 M01/M03 Q1011 R25L/99// R20/290070 R25R/290068 NOSIG
EBBR 041320Z 20018KT 4000 -SG FEW006 BKN012 M01/M03 Q1011 R25L/99// R20/290070 R25R/290068 NOSIG
EBBR 041350Z 20017KT 8000 -SG FEW008 SCT012 BKN022 M01/M03 Q1011 R25L/99// R20/290070 R25R/290068 NOSIG
EBBR 041420Z 19018KT 9999 FEW012 BKN018 M00/M03 Q1011 R25L/99// R20/290072 R25R/290072 TEMPO 4000 -SN BKN012
EBBR 041450Z 19016KT 9999 FEW012 BKN018 M00/M03 Q1011 R25L/99// R20/290072 R25R/290072 TEMPO 4000 -SN BKN012
EBBR 041520Z 20016KT 9000 -SN FEW012 BKN018 00/M02 Q1011 R25L/99// R20/290072 R25R/290072 TEMPO 4000 -SN BKN012
EBBR 041550Z 19016KT 5000 -SN FEW012 BKN015 M00/M02 Q1010 R25L/99// R20/290072 R25R/290072 TEMPO 2500 SN BKN006
EBBR 041620Z 20017KT 7000 -SN FEW012 BKN014 00/M02 Q1010 R25L/99// R20/290072 R25R/290072 TEMPO 2500 SN BKN006
EBBR 041650Z 20016KT 9999 -SN BKN012 00/M02 Q1010 R25L/99// R20/290072 R25R/290072 TEMPO 2500 SN BKN006
EBBR 041720Z 19017KT 4000 -SN BKN012 00/M02 Q1010 R25L/99// R20/290072 R25R/290072 TEMPO 2500 SN BKN006
EBBR 041750Z 19017KT 2000 SN FEW009 BKN012 M00/M02 Q1010 R25L/99// R20/290063 R25R/290067 TEMPO 1200 SN BKN006
EBBR 041820Z 19015KT 2400 SN BKN010 M00/M01 Q1009 R25L/99// R20/290063 R25R/290067 TEMPO 1200 SN BKN006
EBBR 041850Z 19017KT 2100 SN BKN010 M00/M02 Q1009 R25L/99// R20/590532 R25R/590545 TEMPO 1200 SN BKN006
EBBR 041920Z 19016KT 5000 SN BKN014 00/M02 Q1008 R25L/99// R20/590532 R25R/590545 TEMPO 1200 SN BKN006
EBBR 041950Z 19016KT 5000 -RASN BKN013 01/M01 Q1008 RESN R25L/99// R20/590532 R25R/590545 TEMPO 2500 RASN BKN008
EBBR 042020Z 19017KT 8000 -RASN BKN014 01/M01 Q1007 RERASN R25L/99// R20/590532 R25R/590545 TEMPO 2500 RASN BKN008
EBBR 042050Z 19018KT 7000 RASN BKN016 01/M00 Q1007 R25L/99// R20/590532 R25R/590545 TEMPO 2500 RASN BKN008
EBBR 042120Z 20015KT 6000 RA BKN015 02/M00 Q1007 R25L/99// R20/590532 R25R/590545 TEMPO 2500 RASN BKN008
EBBR 042150Z 20017KT 8000 RA BKN017 02/M00 Q1007 R25L/99// R20/290051 R25R/290058 TEMPO 4500 RA
EBBR 042220Z 20014KT 8000 RA SCT014 BKN018 02/00 Q1007 R25L/99// R20/290051 R25R/290058 TEMPO 4500 RA
 

 

Time lapse of webcam images between 1200-1346 CET showing how some snow added 1 cm to the already present 5 cm. It was one of very few occasion some descent falling snow could be captured during daylight.

 

04/12/2010. Snow height in cm taken from the synops of 1200, 1500, 1800 & 2100 UTC.

 

Min temperatures of December 4 were the lowest for the center, in fact it was reached the late evening of December 3. (Gardens Tmin was also -9,7C).

 

04/12/2010 0832 SE. In fact these were the first real rays of sunshine during the cold wave, here shining on the village Humelgem.

 

04/12/2010 0834 SE. Wider view.

 

04/12/2010 1256 NE. First snow belt passed by around noon with church of Steenokkerzeel almost obscured by the snow.

 

04/12/2010 1259 W. An Hercules is towed to a location where it can perform engine run tests.

 

04/12/2010 1301 N. Road traffic began to jam a bit.

 

04/12/2010 1435 W. Surely this Russian Ilyushin 76 must felt home when it arrived at Brussels Airport as part of cargo transport on an upcoming visit of the president of Russia. Six hours later, the winter landscape gradually disappeared under loads of rain.

 

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