Weather pictures & report of December 16 2010

 

Snow related to cold front.


Synopsis: at 500 hPa a ridge stretching from Greenland to the southern parts of the Atlantic Ocean and on the eastern side a sharpening trough west of Norway. Overhead in the NW'ly airflow the crossing of warm and cold front with on the latter precipitation transforming from liquid to solid form. It induced a couple cm of snow in most parts of Flanders and was the start of a second cold wave. All pictures of  December 16 were taken at Kampenhout (central Belgium), on December 17 five km further southwestwards at Steenokkerzeel. Hours in local time (CET). 

 

Surface analysis of December 16 2010 at 1900 CET. Cold front over the centre of Belgium moving SE-wards. (Source chart: Belgocontrol)

 

Loop of 12 surface analyses of December 16 between 1300-2400 CET with the weather plots. (Source: meteocentre.com)

 

Upper air analysis 500 hPa of December 16 2010 at 1300 CET. Sharpening trough (cold pool) west of Norway and Northsea plunging SSE-wards. Within 12 hrs overhead temperatures descended from -25C to -35C. (Source chart: DWD via wetter3)

 

Upper air analysis 850 hPa of December 16 2010 at 1300 CET. In a NW'ly flow, the minus 11 degrees was advected into our area during the evening. (Source chart: DWD via wetter3)

 

Loop of forecasted soundings for Brussels of December 16 2010 between 0830-1900 CET. Around 1800 CET sudden veering winds advected negative temperatures over the entire layer. (Source: RASP)

 

Another loop of forecasted soundings for Brussels between December 16 1300 CET and December 17 1300 CET. Same wintry turn between 1600-1900 CET, afterwads staying cold over the entire layer but gradually becoming dry. (Source: weatheronline.co.uk)

 

16/12/2010 1745-1900 CET. Satellite loop in the infra-red channel. Massive cloudiness related to the warm and cold front crossing the Low Countries. (Source sat picture: Eumetsat via Sat24.com)

 

16/12/2010 1341 CET. Satellite in the visual channel. Massive cloudiness related to the warm and cold front crossing the Low Countries with behind the convective cells. (Source satpicture: NOAA and University of Bern)

 

Radar loop (reflectivity in dBZ) between December 16 1600 CET and December 17 1200 CET. Intensive precipitation of warm and cold front, with along cold front also a brighter stripe (passing EBBR at 1710 UTC (or 1810 CET)). Later in the night a line of snow showers came in. (Source radar picture: Belgocontrol).

 

16/12/2010. Corresponding radar wind profiler at Brussels Airport between 1600-1800 UTC giving clear evidence of a sharp directional shear in the lowest 1,5 km on passage cold front which happened at Brussels Airport around 1710 UTC. Legend: vertical axis height in km, horizontal axis time step each 20 minute with the oldest data on the left hand side (Source radar picture: Belgocontrol).

 

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


EBBR 161050Z 23015KT 2500 -DZ FEW004 BKN005 02/01 Q1008 R25L/290072 R02/290062 R25R/290064 TEMPO 1400 RADZ BKN004
EBBR 161120Z 23015KT 2500 -DZRA FEW004 BKN005 02/01 Q1006 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 1400 DZRA BKN004
EBBR 161150Z 22017KT 2500 -DZRA FEW004 BKN006 03/02 Q1005 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 1400 DZRA BKN004
EBBR 161220Z 23016KT 4000 -RADZ FEW004 BKN007 03/02 Q1004 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161250Z 22017KT 6000 -RADZ FEW004 BKN007 03/02 Q1003 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161320Z 23016G26KT 7000 -RA FEW006 BKN008 03/02 Q1002 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161350Z 23016KT 8000 -RA SCT007 BKN010 03/02 Q1001 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161420Z 23017KT 7000 RA SCT007 BKN010 03/02 Q1000 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161450Z 24015KT 4000 RA SCT008 BKN012 04/02 Q0999 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 2000 RADZ BKN004
EBBR 161520Z 25015KT 7000 RA SCT008 BKN011 04/02 Q0998 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 3000 RADZ BKN007
EBBR 161550Z 24014KT 8000 RA BKN010 04/02 Q0997 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 3000 RADZ BKN007
EBBR 161620Z 24015KT 7000 RA BKN010 04/02 Q0996 R25L/290072 R02/290062 R25R/290064 TEMPO 23017G27KT 3000 RADZ BKN007
EBBR 161650Z 24015KT 7000 RA BKN010 04/02 Q0996 R25L/290072 R02/290062 R25R/290064 BECMG 02017G27KT 2000 -RASN=
EBBR 161720Z 02015KT 1700 SN SCT002 BKN005 M00/M01 Q0997 RERA R25L/290072 R02/290062 R25R/290064 TEMPO 1200 SN BKN002
EBBR 161750Z 03012KT 1400 R25L/1700D R25R/1000VP2000U R02/1500VP2000N SN SCT002 BKN004 M00/M01 Q0997 R25L/290072 R02/290062 R25R/290064 TEMPO 0900 SN BKN002
EBBR 161820Z 04011KT 2000 SN SCT002 BKN004 M00/M02 Q0997 R07R/591040 R02/591045 R07L/591041 TEMPO 0800 SN BKN002
EBBR 161850Z 04007KT 2000 SN SCT002 BKN004 M00/M01 Q0997 R07R/591040 R02/591045 R07L/591041 TEMPO 1400 SN BKN002
EBBR 161920Z 04006KT 2000 SN SCT002 BKN006 M00/M01 Q0997 R07R/591040 R02/591045 R07L/591041 TEMPO 1400 SN BKN002
EBBR 161950Z 04004KT 2500 -SN SCT003 BKN004 M00/M01 Q0997 RESN R07R/591040 R02/591045 R07L/591041 NOSIG
EBBR 162020Z 06002KT 6000 -SN SCT003 SCT004 M01/M01 Q0997 R07R/592035 R02/592040 R07L/590545 NOSIG
EBBR 162050Z 35002KT 3900 BR SCT003 BKN006 M01/M02 Q0997 R07R/592035 R02/592040 R07L/590545 NOSIG
EBBR 162120Z 35002KT 4000 BR SCT005 SCT010 M01/M01 Q0997 R07R/592035 R02/592040 R07L/590545 NOSIG
EBBR 162150Z 36002KT 4500 BR SCT005 BKN010 M01/M01 Q0997 R07R/592035 R02/592040 R07L/590545 NOSIG
EBBR 162220Z 34003KT 4500 BR SCT004 BKN012 M01/M02 Q0997 R07R/592035 R02/592040 R07L/590545 NOSIG
EBBR 162250Z 34003KT 7000 BKN010 M01/M02 Q0997 R07R/690341 R02/690648 R07L/690353 NOSIG
 

Between 1650-1720 UTC frontal passage, a closer investigation below via screenshots of some meteo sensors at Brussels Airport.

 

16/12/2010. Evolution of air temperature at Brussels Airport: at 1709UTC still +3,6C,
afterwards rapidly dropping and holding at -0,2C at 1714UTC.

 

16/12/2010. Evolution of the pressure at the barometer level of Brussels Airport
(add 6,7 hPa for reducing to sea level). A strong pressure rise does occur at 1709-1710 UTC
which should correspond with passage of cold front.

 

16/12/2010. Evolution of wind direction / speed at the end of runway 25L at Brussels Airport.
Between 1708-1710UTC a strong wind shift from 280 to 010 degrees, another clue for frontal
passage.

 

16/12/2010. Evolution of precipitation rate at Brussels Airport: at 1715 UTC a peak did occur
of 0,46 mm/minute (= 27,6 mm/h). Before that, a couple minutes of ice rain did fall and probable
this package melted at once.

 

17/12/2010. Snow height in cm taken from the synops of 0600 UTC.

 

16/12/2010 2220. Proof of the date. The backside of cold front gave at my location 2 cm, next morning the showers added 1 cm.

 

16/12/2010 2242. View of a garden.

 

16/12/2010 2242 E. View of a field with in the sky the anti collision lights of an incoming airplane for Brussels Airport.

 

17/12/2010 1014 NNW. Next day, view towards Mechelen from the control tower at Brussels Airport.

 

17/12/2010 1015 E. View towards village of Steenokkerzeel.

 

17/12/2010 1016 W. View towards Brussels Airport.

 

17/12/2010 1019 NE. View towards Kampenhout.

 

17/12/2010 1021 E. View towards Nederokkerzeel.

 

17/12/2010 1218 W. View towards Brussels City with Brucargo in foreground.

 

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