Weather pictures & report of July 14 2010


MCS (squall line) thunderstorm along convergence line.

Synopsis: at 500 hPa, east of a relaxing trough west of the British Isles, our area in a moderate SW'ly flow of warm and humid potentially unstable air. At surface passage of thermal depression, related convergence line enhanced the instability which started from noon over France. From the afternoon on, a developing MCS thunderstorm entered the S of Belgium moving NE-wards. It evolved over central and eastern parts to a trailing stratiform squall-line with several bow echo segments resulting in wind damage at many locations, mostly due to downbursts. Over central Belgium it resulted again (third within five days) in a nice shelf cloud. Unless otherwise stated, all pictures were taken at Steenokkerzeel (central Belgium), hours in local time (CET). 


Surface analysis of July 14 2010 at 1400 CET. Related to a thermal depression over the channel, a convergence line over northwest France which crossed Belgium during the afternoon from SW to NE. (Source chart: Belgocontrol)


Loop of 8 surface analyses (of each hour between 1300 - 2000 CET) with weather plots showing the slow movement of the thermal depression. (Source:


Upper air analysis 500 hPa of July 14 2010 at 1400 CET. Related to a low near Ireland, a relaxing long wave trough over the Gulf of Biskaye moving eastwards. On the other hand a retreating ridge near Austria. Our area in a strong SW'ly airflow. (Source chart: DWD via wetter3)


Upper air analysis 850 hPa of July 14 2010 at 1400 CET. Recognizable in the strengthening SW'ly flow is a relative strong temperatures gradient: overhead 13°C and a bit further to the west dropping to 8°C . (Source chart: DWD via wetter3)


Loop of forecasted soundings for Brussels of July 14 2010 between 0830-2000 CET. Deep instability is present from 750 hPa upwards, initially a strong inversion is present but cleared from 1500 CET onwards. Around this time shear in speed has become quite strong: low level (0-3 km) 40 kt, deep layer (0-6km) 50 kt. Besides this, relative helicity SREH 0-3 km was temporary moderate with values >200 m˛/s˛. Together with moderate CAPE this enhanced the risk of large multicells (MCS) eventually preceded by supercells. (Source: RASP)


Another loop of forecasted soundings for a 12 hours period (in steps of three hours) of Brussels from July 14 2010, 1100 CET onwards. Included are some thunderstorms indices: surface based CAPE went up to around 1500 J/kg, KI 38, TT 52, LI -5 = strong convective potential which may lead to scattered to numerous thunderstorms, scattered severe. (Source:


14/07/2010 1500-1930 CET. Satellite loop in the visual channel. Exploding MCS comes in from the north of France. Severe activity (mainly downbursts) was to be found in many parts of Belgium except for the northwestern provinces. (Source sat picture: Eumetsat via


14/07/2010. Still image in the visible channel showing the exploding Cb's on a NNW-SSE orientated line. (Source picture: NOAA)


14/07/2010. With corresponding temperature scale on which can be concluded that at that time the most active cells were still just south of the Belgian border. (Source picture: NOAA via


14/07/2010. Couple of hours later in this wider view, first evidence of an MCS in form of a squall line. (Source picture: Metsat via


Radar loop (rainfall rate in mm/hr) of July 14 2010 between 1440-1950 CET. An extensive precipitation belt comes in from the SW. Most intense echo's were to be found over the provinces Hainaut and Namur. A squall line with several bow echo segments developed over the Ardennes (although on these 125 km radius images not very good identifiable). Precipitation tops went up to around an impressive 16 km. (Source radar picture: Belgocontrol)


14/07/2010.  Composite radar image of 1615 CET where the MCS indicates a squall line (orange colors) with on the northern side also a bow echo. On this line (especially along the bow echo) local wind damage was to be found and considering the length of the entire line it could be labeled as a derecho. Furthermore it reveals that this quasi linear squall line is of the stratiform trailing type  (Source picture: IRM via Meteoservices)


Corresponding discharges of July 14 2010 between 1515-1815 CET giving again clue to the appearance of a long squall line. (Source lightning picture: Euclid)


14/07/2010. Zooming in over Belgium it shows that most activity was to be found over a line east of Ath-Brussels-Turnhout. (Source picture: Buienradar)


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

Brussels Airport: there is evidence of a 270° backing wind, a drop in temperature of almost 10°C, but furthermore no clue about the other severe weather elements that came along between 1434-1448 UTC.
EBBR 141250Z VRB05KT CAVOK 28/14 Q1003 NOSIG=
EBBR 141320Z 19004KT 130V230 CAVOK 29/14 Q1002 TEMPO 24025G40KT 3000 SHRA TSRA SCT015 BKN030CB=
EBBR 141350Z 03006KT CAVOK 28/15 Q1001 TEMPO 24025G40KT 3000 SHRA TSRA SCT015 BKN030CB=
EBBR 141420Z 33015KT 9999 -SHRA FEW048CB 25/15 Q1000 TEMPO 24025G40KT 3000 SHRA TSRA SCT015 BKN030CB=
EBBR 141450Z 26019KT 6000 -TSRA FEW009 BKN018CB 19/17 Q1005 NOSIG=
EBBR 141520Z 27016KT 5000 -TSRA FEW009 BKN018CB 19/17 Q1005 NOSIG=
EBBR 141550Z 29009KT 250V320 9999 -SHRA FEW009 SCT018CB 19/17 Q1005 RETS NOSIG=

Metars of Charleroi (EBCI) which gave more info regarding the events that happened also at Brussels
EBCI 141250Z VRB07KT CAVOK 30/14 Q1003 NOSIG=
EBCI 141320Z 11008KT 070V150 CAVOK 28/14 Q1002 TEMPO VRB20G35KT 2500 TSRA BKN030CB=
EBCI 141350Z 06013KT 9999 FEW030CB 28/14 Q0999 TEMPO VRB20G35KT 2500 TSRA BKN030CB=
EBCI 141420Z 28020G45KT 240V320 1900 R25/1100VP2000U TSRA FEW016 BKN026CB 17/16 Q1003 NOSIG=
EBCI 141450Z 28012G25KT 230V320 4500 TSRA SCT006 BKN028CB 18/16 Q1005 NOSIG=
EBCI 141520Z 27008KT 240V300 8000 -RA BKN007 FEW028CB 18/16 Q1006 RETS NOSIG=
EBCI 141550Z 24007KT 200V270 7000 -RA BKN006 18/16 Q1006 NOSIG=

Metars of Bierset (EBLG)
EBLG 141420Z 14014KT 110V170 CAVOK 31/13 Q1000 TEMPO TSRAGR VRB25G45KT BKN025CB=
EBLG 141450Z 14015KT 110V170 CAVOK 31/15 Q1000 TEMPO VRB25G45KT 0800 TSRAGR BKN015CB=
EBLG 141520Z 27025G39KT 230V300 0800 R23L/P1500N R23R/P1500N R05R/P1500N +TSRA BKN002 BKN015CB 18/17 Q1002 TEMPO VRB25G45KT 0800 TSRAGR BKN015CB=
EBLG 141550Z 26017KT 5000 -TSRA SCT008 SCT015CB BKN040 18/17 Q1005 TEMPO VRB25G45KT 2500 TSRA BKN015CB=
EBLG 141720Z 22005KT 190V270 9999 SCT008 19/17 Q1005 NOSIG=

Metars of Florennes (EBFS) where speci report are still included with more detailed info regarding timing of the storm.
EBFS 141355Z 13014KT 8000 FEW040CB BKN140 BKN250 28/15 Q1000 BLU=
EBFS 141402Z 15016KT 5000 FEW040CB SCT070 BKN150 29/15 Q1001 WHT=
EBFS 141404Z 24023G42KT 3000 SHRA FEW040CB SCT070 BKN150 28/16 Q1003 YLO=
EBFS 141406Z 25025G42KT 1200 TSRA SCT020CB SCT070 BKN150 23/18 Q1003 AMB=
EBFS 141415Z 29014G27KT 3500 RA FEW003 SCT040CB BKN060 18/18 Q1001 YLO=
EBFS 141520Z 29013KT 9999 FEW004 SCT040 BKN080 17/16 Q1006 BLU=
EBFS 141525Z 28012KT 9999 FEW004 SCT038 BKN070 17/16 Q1006 BLU=
EBFS 141555Z 29014KT 8000 -RA SCT005 FEW015CB BKN050 16/16 Q1006 YLO=


14/07/2010. Observed wind gust (in kt) of the official Met stations showing values between 45-74 kt over the south, center and east. At Brussels Airport 45 kt was offically recorded, but one unoffical anemometer gave a gust of 63 kt. 


14/07/2010 1530. This threatening sky appeared at Merbes-le-Chateau (south of province Hainaut) and it corresponds with the most intense echo to be found on the radar pictures. Near this location large hail of around 4 cm diameter was observed. (Source picture: "Maka" on forum Meteobelgium)


14/07/2010 1610. Panoramic view at Gosselies (Brussels South) with approaching arcus cloud (Source pic: V. Bouchez)


14/07/2010 1620. Tuba features were visible near Namur. This could support the theory that a tornado might be responsible for the most intense wind damage of the entire country which was to found a bit further to the east, namely in Ciney, province Namur. (Source picture: via Sébastien Verachtert on forum Meteobelgium)


14/07/2010 1620. Wider view on several tuba's. (Source picture: via Sébastien Verachtert on forum Meteobelgium)


14/07/2010 1619 S. Events from my point of view in the center of Belgium located at "BR" on the radar pictures: first glimpse of an incoming arcus cloud which in the far south looked quite impressive.


14/07/2010 1619 S. Zoomed in with a bit enhanced contrast.


14/07/2010 1621 SW. The view more to the west was less impressive.


14/07/2010 1624 S. Evolution of southern side.


14/07/2010 1626 S.


14/07/2010 1629 S.


14/07/2010 1626 S. Zoomed in on the blowing dust of the arriving wind gusts.


14/07/2010 1630 S. Final clear view on the approaching shelf.


14/07/2010 1632 SSE. Precipitation arrived with blustering winds of around 45 kt or perhpas even more as one of the unofficial anemometers showed a peak of 63 kt.


14/07/2010 1634 SW. View towards the airport, obscured by the precipitation.


14/07/2010 1641 NE. Opposite view towards Steenokkerzeel village. A total of 18 mm water was collected.


To summarize things: time lapse of the events between 1618-1631 CET with view to the south showing the approach and passage of a thunderstorm with shelf cloud and severe wind gusts. Catching feature is undoubtly the contrary wind that can be detected via the clouds which gave of course severe turbulence closing the airport for half an hour. 


14/07/2010. Corresponding radar wind profiler at Brussels Airport between 1530-1630 CET giving clear evidence of a sharp directional shear in the lowest 4 km. Legend: vertical axis height in km, horizontal axis time step each five minute with the oldest data on the left hand side (Source radar picture: Belgocontrol).


14/07/2010. Another radar wind profiler at Brussels Airport between 1625-1725 CET  (Source radar picture: Belgocontrol).


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