heavy floods episodes on the 11 th and 12 th november 2008 south african case study
DESCRIPTION
Heavy floods episodes on the 11 th and 12 th November 2008 South African case study Isaac Ngwana. Outline. General rainfall patterns Main weather systems Observation network Case study Model results and verification Conclusion. Rainfall patterns in SA. - PowerPoint PPT PresentationTRANSCRIPT
Heavy floods episodes on the 11th and 12th November 2008
South African case study
Isaac Ngwana
Outline
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 2
• General rainfall patterns• Main weather systems• Observation network• Case study• Model results and verification• Conclusion
Rainfall patterns in SA
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 3
Main weather systems- responsible for flooding events
TTTTropical cyclonesCut off lowFrontal system
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011
4
Weather observation stations in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09 Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 5
• SURFACE OBSERVATIONS 23 climate stations 23 sea surface temperature stations 25 weather offices 35 electric _manual (aws manned) 156 automatic weather stations – unmanned 165 automatic rainfall stations 1257 rainfall (monthly; ~50 provide daily data)• UPPER AIR OBSERVATIONS• 9 Upper air stations ( Including the ISLANDS – Marion and
Gough)
Weather observation stations in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09 Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 6
Weather observation stations in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09 Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 6
RADAR NETWORK in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09 Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 7
Case study (11 & 12 Nov 2008) - general damage
Document Reference: SMRF-PSN-NGW04-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 8
• 47 people were killed • Thousands evacuated • Roads and bridges swept away
Warning System-print media
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 9
Early Warning System-print media cont…
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 10
11 November 2008
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 11
Observations - 11 November 2008
11
Observed 24 hr rainfall 11 & 12 Nov 2012
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 12
11 November 2008
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 13
Observations -12 November 2008
13
Weather systems – 11 Nov 2012
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 14
Observed weather -11 Nov 2008
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 15
Observed weather 12 Nov 2008
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 16
Observed weather -12 Nov 2008
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 17
NWP Modeling in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 18
NWP Modeling in South Africa
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 19
Model Domain Assimilation
UM SA12 Large No data assimilation
UM SA12 Large Data assimilation
UM SA15 Small No data assimilation
WRF SA12 Large No data Assimilation
WRF SA15 Small No data assimilation
Modeling - weather systems 12 -48 hr forecast
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 20
12 November 2008
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 21
12 November 2008
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 22
Model -12 November 2008
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 23
Eye ball verification
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 24
Warning System-SAWS website
Document Reference: SMRF-PSN-NGW004-001-2011-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 25
Conclusion
Document Reference: SMRF-PSN-NGW004-001-2012-05-09Document Template Reference: AWC-PSN-001.1 Date of last revision: 26 August 2011 26
• 11 &12 Nov 2008 flooding events were well forecast by the model
• Forecast warning were issued in time• Necessary steps were taken by government
dept. even though 47 people lost their lives• Good observation data bank, but sparse • Local data ingest might improve model
forecast