Weather pictures & report of June 18 2012

 

MCS (squall line) thunderstorm along wave top of cold front.


Synopsis: at 500 hPa, Belgium east of an long wave upper trough. During the morning, a a stro,g SW'ly flow, a wave on the polar cold front crossed central parts of Belgium. East of it advection of warm, moist and potentially unstable air. In this system an MCS (squall line) did form and when moving over the eastern parts of Belgium it took the shape of a bow echo. It resulted locally in wind damage due to some downbursts, highest wind speed detected by the official weather stations was even 59 kt at Florennes. At my location, a heavy shower passed (rain rate 94 mm/h) with weak to moderate thundery activity and gusts not exceeding 25 kt. Also a shelf cloud could be detected just ahead of the system. All pics taken at Steenokkerzeel (central Belgium), hours in local time (CET). 

 

Surface analysis of June 18 2012 at 0800 CET. In a SW'ly flow, a wave on the polar front was crossing over the center of Belgium.  (Source chart: Belgocontrol)

 

Upper air analysis 500 hPa of June 18 2012 at 0200 CET. Major trough between Scotland and Iceland. A weak mobile ridge crossed Belgium early night in a strengthening SW flow. A short wave trough over SW France was approaching fast, reaching Belgium in the morning  (Source chart: DWD via wetter3)

 

Upper air analysis 850 hPa of June 18 2012 at 0200 CET. Recognizable again the major trough north of the British Isles with a smaller one extending towards the Bay of Bisaye. Belgium in a moderate S'ly flow advecting warm air over the eastern parts (13°C). (Source chart: DWD via wetter3)

 

Loop of forecasted soundings for a 12 hours period (in steps of three hours) of Brussels from June 17 2012, 2300 CET onwards. Included are some thunderstorms indices: most unstable surface based CAPE went up to almost 170 J/kg, KI 30, TT 49, LI -0. It meant a rather weak convective potential but with a dynamical trigger it still could lead to scattered thunderstorms. SREH  up to 300 m²/s², in combi with the rather weak CAPE, the environment would be favorable for multicell thunderstorms. (Source: weatheronline.co.uk)

 

Forecasted vertical profile and surface temperature for Brussels Airport of June 18 from 0200 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. At the begin, between 0500-0700UTC, passage of a saturated layer extending from 4000 ft to 31000 ft. The shear in speed was quite strong, also in direction moderate. (Source: Belgocontrol)

 

Forecasted precipitation, 2 meter temperature for Brussels Airport of June 18 from 0200 CET and the following 48 hours. Legend: precipitation darkest green = dynamical rain, light green is convective rain. Wind in kt. A burst of dynamical rain between 0500-0600UTC, but in fact it was obscuring a convective signal. Note also the radical change in direction of wind of 180 degrees. (Source: Belgocontrol)

 

18/06/2012 0545-0715 CET. Satellite loop in the visual channel. A massive cloud plume covering Belgium with at the begin also an overshooting top near province Namur. (Source sat picture: Eumetsat via Sat24.com)

 

Radar loop (rainfall rate in mm/hr) of June 18 2012 between 0500-0840 CET. Widespreas and some intense echos crossed fast from SW to NE over Belgium. Detectable is also a bow echo over the eastern parts. Precipitation tops up to 12 km. Pictures on the field (see further below) were taken near "BR". (Source radar picture: Belgocontrol)

 

18/06/2012. Highlighted is the bow echo. (Source picture: Buienradar)

 

18/06/2012. Amount of discharges over the Benelux over a period of 2 hours from 0600 CET onwards. As can be noted, it was quite active with over 7000 discharges of which around 5000 over Belgium. (Source picture: Blids)

 

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

Florennes

EBFS 180255Z 09005KT 9999 SCT050 SCT250 11/09 Q1011 BLU=
EBFS 180325Z 10006KT 9999 SCT050 SCT250 12/09 Q1011 BLU=
EBFS 180355Z 10005KT 9999 TS FEW040CB SCT250 12/09 Q1010 BLU=
EBFS 180357Z 11005KT 9999 TS SCT040 SCT220 12/09 Q1010 BLU=
EBFS 180425Z 09005KT 9999 -TSRA SCT040CB SCT120 BKN220 12/10 Q1009 BLU WHT TEMPO YLO=
EBFS 180438Z 11007KT 7000 -TSRA SCT036CB BKN100 14/11 Q1010 WHT WHT TEMPO YLO=
EBFS 180439Z 13007KT 4900 TSRA SCT035CB BKN110 14/11 Q1011 GRN WHT TEMPO YLO=
EBFS 180440Z 14007KT 3500 TSRA FEW015 SCT032CB BKN090 14/11 Q1011 YLO WHT TEMPO YLO=
EBFS 180448Z 19011G59KT 3800 TSRA FEW012 SCT030CB BKN090 13/12 Q1011 GRN WHT TEMPO YLO=
EBFS 180455Z 20014G24KT 4000 TSRA FEW012 SCT025CB BKN090 13/12 Q1012 GRN WHT TEMPO YLO=
EBFS 180525Z 26008KT 7000 -TSRA SCT014 FEW025CB BKN100 12/11 Q1011 GRN WHT TEMPO YLO=
EBFS 180555Z 26006KT 7000 -RA FEW003 SCT010 BKN100 12/12 Q1011 RETS GRN WHT TEMPO YLO=
EBFS 180611Z 29005KT 7000 -RA FEW003 BKN007 BKN080 12/12 Q1012 RETS GRN GRN TEMPO YLO=
 

Charleroi

EBCI 180350Z 09007KT CAVOK 13/10 Q1010 NOSIG=
EBCI 180420Z 07007KT 9999 -TSRA FEW030CB 13/10 Q1009 TEMPO VRB20G40KT 2000 TSRA BKN030CB=
EBCI 180450Z 25015G26KT 1300 R25/P2000N +TSRA FEW005 BKN032CB 12/11 Q1012 TEMPO VRB20G40KT=
EBCI 180520Z 28007KT 240V320 1900 TSRA FEW005 BKN032CB 12/11 Q1012 NOSIG=
EBCI 180550Z 33006KT 270V360 5000 -RA SCT003 BKN032CB 12/11 Q1011 RETS NOSIG=
EBCI 180620Z 35006KT 310V030 6000 BKN004 SCT032CB 12/12 Q1011 RETS NOSIG=
EBCI 180650Z 10004KT 040V170 9999 BKN005 13/12 Q1012 BECMG SCT008=


Brussels

EBBR 180320Z 08005KT CAVOK 13/10 Q1011 TEMPO 21020G30KT 3000 SHRA=
EBBR 180350Z 08005KT CAVOK 13/10 Q1010 TEMPO 21020G40KT 2000 +TSRA BKN008=
EBBR 180420Z 09005KT 060V120 CAVOK 13/10 Q1010 TEMPO 21020G40KT 2000 +TSRA BKN008=
EBBR 180450Z 36005KT 340V040 8000 TSRA SCT030CB BKN046 13/10 Q1009 TEMPO 21020G40KT 2000 TSRA BKN008=
EBBR 180520Z 30014KT 270V330 3000 +TSRA FEW010 BKN030CB 12/11 Q1012 TEMPO 21020G40KT 2000 +TSRA BKN008=
EBBR 180550Z 34008KT 300V360 3000 TSRA SCT004 BKN020CB 12/11 Q1011 NOSIG=
EBBR 180620Z 31007KT 6000 -RA SCT005 BKN048 13/11 Q1011 RETS NOSIG=
EBBR 180650Z 01006KT 350V050 8000 FEW007 SCT048 13/12 Q1011 NOSIG=
EBBR 180720Z VRB01KT 9999 FEW010 15/12 Q1012 NOSIG=

 

Diest

EBDT 180325Z 07005KT 9999 FEW085 13/10 Q1011 BLU=
EBDT 180411Z 09005KT 9999 FEW090 BKN240 14/10 Q1010 BLU WHT TEMPO GRN=
EBDT 180425Z 09006KT 9999 FEW090 BKN220 14/10 Q1010 BLU WHT TEMPO GRN=
EBDT 180446Z 07005KT 9999 TS FEW030CB BKN180 14/10 Q1009 BLU WHT TEMPO GRN=
EBDT 180513Z 07004KT 7000 -TSRA FEW030CB FEW065 BKN105 BKN170 14/10 Q1009 WHT GRN TEMPO YLO=
EBDT 180527Z 18010KT 4000 TSRA FEW030CB FEW047 SCT070 BKN095 13/11 Q1011 GRN YLO TEMPO AMB=
EBDT 180529Z 19009KT 1800 TSGSRA SCT030CB SCT070 BKN095 13/12 Q1011 YLO YLO TEMPO AMB=
EBDT 180530Z 18006KT 1200 +TSRA FEW007 SCT020CB SCT047 BKN070 13/12 Q1010 AMB YLO TEMPO AMB=
EBDT 180536Z 17005KT 1500 TSRA FEW007 FEW026CB SCT060 BKN095 13/12 Q1010 YLO GRN BECMG WHT=
EBDT 180551Z 26011KT 4000 -TSRA FEW008 SCT020CB SCT028 BKN035 12/12 Q1011 GRN GRN BECMG WHT=
EBDT 180625Z 31006KT 4200 -SHRA FEW015 SCT020TCU BKN025 12/12 Q1010 GRN GRN BECMG WHT=
EBDT 180632Z 31009KT 6000 -RA FEW006 BKN020TCU BKN025 13/12 Q1010 WHT BLU TEMPO WHT=
EBDT 180725Z VRB03KT 7000 FEW003 BKN015 14/13 Q1011 WHT BLU TEMPO WHT=
EBDT 180825Z 22004KT 9999 FEW008 BKN015 14/13 Q1013 WHT BLU TEMPO WHT=


Below some picture taken at Steenokkerzeel

18/06/2012 0636 WNW. A shelf cloud in the far distance could be detected (which moved from the left to the right).

 

18/06/2012 0644 W. Bit later.

 

18/06/2012 0645 W. Wider view.

 

18/06/2012 0645 SSW. View more towards the south from where the cloudiness was coming from.

 

18/06/2012 0648 SSW. Bit later, the shelf was a so called "stacked plate shelf".

 

Between 0638-0650, direction west afterwards south, these events were also captured in a time lapse showing the movement of a so called "stacked plate shelf".

 

18/06/2012 0654 W. Beneath the shelf, things were less exciting.

 

18/06/2012 0701 SSW. Pouring rain.

 

18/06/2012 0704 SW. With a low Stratus band preceding more heavy rain. A total of 18 mm was collected within an hour.

 

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