Report On Heavy Rainfall That Caused Floods in Johore and south ...

REPORT ON THE SECOND HEAVY RAINFALL EPISODE
THAT CAUSED FLOODS IN
JOHOR AND SOUTHERN PAHANG
DURING THE PERIOD
11 – 14 JANUARY 2007
PREPARED BY:
RESEARCH DIVISION
MALAYSIAN METEOROLOGICAL DEPARTMENT
MINISTRY OF SCIENCE, TECHNOLOGY AND INNOVASION
16 JANUARY 2007

1.Introduction
Johor and southern Pahang experienced a second heavy rainfall episode from 11 to 14
January 2007. This heavy rainfall episode was the first event in which heavy rainfall reoccurred
within a period of 22 days (19 December 2006 – 11 January 2007). This abnormal heavy rainfall
event was due to the convergence of the strong winds from the western Pacific Ocean and the
northeasterly surge form Rusia/ China over the South China Sea.
2.Analysis of rainfall from 11 – 14 January 2007
Table 1: Daily Accumulated Rainfall (mm) from 11 January 2007 to 14 January 2007
State
Station
Thursday
(11/1/07)
Friday
(12/1/07)
Saturday
(13/1/07)
Sunday
(14/1/07)
Total
Pahang
Muadzam
Shah
67.0 58.0 69.0 36.0 230.0
Johor Mersing 64.0 134.0 237.0 167.0 602.0
Senai 264.0 213.0 9.0 19.0 505.0
Kluang 171.0 222.0 42.0 16.0 451.0
Batu Pahat 121.0 94.0 9.0 0.4 224.4
Table 2: January Accumulated Rainfall (1/1/2007-14/1/2007) in comparison with the Monthly
Accumulated Mean.
State Station
Total Rainfall (mm) Monthly Mean Monthly Monthly
1/1/07 - 14/1/07 (mm) Maximum (mm) Minimum (mm)
Pahang Muadzam Shah 298.6 267.0 644.0 8.0
Johor Mersing 739.2 328.0 834.0 1.0
Senai 607.0 194.0 478.0 8.0
Kluang 488.4 158.0 496.0 1.8
Batu Pahat 275.8 167.0 301.0 27.0
Table 1 indicates that the daily rainfall recorded at Mersing station from 11 until 13 January
has increased during these 3 days. Daily rainfall recorded at Mersing station started to decrease on
14 January 2007. Kluang station also had recorded an increase in the daily rainfall from 11 until 12
January 2007. On 13 and 14 January 2007, the daily accumulated rainfall had decreased drastically
to 42.0 mm and 16.0 mm. On 11 Januari 2007, Senai and Batu Pahat stations started to record daily
rainfall of about 264.0 mm and 121.0 mm respectively. The daily rainfall began to decrease on
12 January 2007. On 13 and 14 January 2007, there was a further decrease in the daily rainfall. For
the period of 11 to 14 January 2007, the daily rainfall recorded by Muadzam Shah station was
almost similar to the January monthly mean. The daily accumulated rainfall recorded by all stations
except Muadzam Shah station exceeded the January monthly mean for the respective stations.
(Refer Table 2).

3.Radar imageries from 11 – 14 January 2007
Weather radar imageries from the radar network stations in Peninsular Malaysia are shown in
Appendix A. (Figure (a) to (h)) shows the development of the heavy rainfall occurrence in detail.
Radar imageries were taken in twelve hour intervals starting from the 11 January 2007 (8.00 am)
until the 14 January 2007 (8.00 pm). These imageries are a composite of radar echoes taken from
the six weather radar stations in Peninsular Malaysia. The development of the heavy rainfall event
could be seen from the sequence of the radar echoes. Johor and southern Pahang have been
receiving heavy rainfall starting on 11 January 2007. The rainfall intensity in both states increased
and peaked on 12 January 2007 (8.00 pm). Most of the rainfall was concentrated in Johor. On 13
January (8.00 pm), the rainfall was still concentrated in the same state but with reduced intensity.
On 14 January 2007, the rainfall in Johor began to reduce substantially.
4.Weather Satellite Imageries from 11 – 14 January 2007
MTSAT weather satellite imageries from 11 until 14 January 2007 are shown in Appendix
B (Figure (a) to (h)). Cloud developments were observed over the southern part of Peninsular
Malaysia on 11 January 2007 (8.30 am). Cloud intensity decreased further on 12 January 2007
(8.30 am) but re-intensified at 8.30 pm. On 13 January 2007 around 8.30 am rain clouds began to
cover southern Peninsular Malaysia. However, the situation began to improve by 8.30 pm. Cloud
development began to decrease at 8.30 am, 14 January 2007.
5.Conclusion
The Northeast monsoon is currently active over the South China Sea and is expected to
continue until 20 January 2007. Moderate to occasionally heavy rainfall is still expected over Johor
and Pahang.

APPENDIX A
Sequence of Radar Imageries at 8.00 am and 8.00 pm from 11 to 14 January 2007 [(a) to (h)]
a) 8.00 am, 11 January 2007 b) 8.00 pm, 11 January 2007
c) 8.00 am, 12 January 2007 d) 8.00 pm, 12 January 2007

APPENDIX A (continued)
e) 8.00 am, 13 January 2007 f) 8.00 pm, 13 January 2007
l
g) 8.00 am, 14 January 2007 h) 8.00 pm, 14 January 2007

APPENDIX B
Sequence of MTSAT Weather Satellite Images at 8.30 am and 8.30 pm
from 11 to 14 January 2007 [(a) to (h)]
(a) 8.30 am, 11 January 2007 (b) 8.30 pm, 11 January 2007
(c) 8.30 am, 12 January 2007 (d) 8.30 pm, 12 January 2007

APPENDIX B (continued)
(e) 8.30 am, 13 January 2007 (f) 8.30 pm, 13 January 2007
(g) 8.30 am, 14 January 2007 (h) 8.30 pm, 14 January 2007