“This is the eighth special monsoon article of 2011 and it will follow many more monsoon article”
Monsoon hits Karachi during last week of July!
Karachiites were waiting for some sort of relief from scorching heat since the beginning of the summer, after hearing from Islamabadis or Lahoris about rains, no doubt they used to feel that why no rain here in this crisis-hit city? after much praying, it seemed that nature has finally heard them as on July 26 heavens started to pour in Karachi. These were indeed the much awaited rains for Karachiites who had been eagerly waiting for rainfall since the beginning of the year.
The last rains Karachi had in 2011 was due to a non-monsoon system called western disturbance. On 29 January, 2011, an intense but short spell of rain lashed all parts of the city, at least 9 mm rainfall was recorded, this spell only lasted for 5 to 10 minutes and after that the sun cam shining again as Karachi shivered with cool winds. While the last monsoon rainfall was on 10 September, 2010, a strong well-marked low-pressure system approached Karachi and caused a heavy downpour of 78 mm, accompanied by strong gusting winds of 35 mph (56 km/h) that destroyed the roofs of some mud houses. So we can say that these were indeed a much awaited rainfall!
How did Karachi received this precipitation?
On July 20, an upper air cyclonic circulations (UAC) formed over West Bengal that intensified into a low pressure on July 21 over the same area. On July 21 night, the low pressure system went under massive period of intensification that transformed into a depression that to over land. The depression started weakening the other day and went from West Bengal to Jharkhand to Utter Pradesh. From here it went to Madya Pradesh and slowly slowly entered Rajasthan on July 25. The moisture started to reach Sindh including Karachi from July 25, when the system weakened into an upper air cyclonic circulation over North Gujarat and Rajasthan. But it was July 26 when this system moved to coastal Gujarat and thunderstorms started to develop over the North-eastern parts of Karachi at about 2:30 pm PST.
At first the thunderstorms kept facing stable air and lack of heat, not to mention that it had ample of moisture but stable air and lack of heat delayed its arrival but suddenly at about 2:51 pm PST the thunderstorms went from developing stages to mature stage process and this process was completed at about 4:45 pm PST and after 5:00 pm PST thunderstorms started lashing different localities of Karachi. The thunderstorms were not severe at all, they were poorly organized but managed to cause rainfall. The winds were from North-East at about 42 km/h, the temperature however dropped from 35°C to 27°C during the period of shower but high humidity made the weather unpleasant. Following is the amount of rainfall that occurred in Karachi due to this thunderstorm;
- 1 mm was recorded in Gulshan-i-Hadeed, Nazimabad, the Masroor airbase and North Karachi.
- 4.4 mm rainfall was recorded on University Road.
- 2 mm rainfall was recorded at Saddar.
- 3 mm rainfall was recorded at the PAF Faisal base.
- 7.2 mm rainfall was recorded at the Jinnah airport. (Highest of Karachi!)
Rains bring usual memory backs
Is more on the why?
The Upper air cyclonic circulations (UAC) as of 9:32 am PST is over coastal Gujarat, it may move a slightly west wards thus bringing cloudy weather to south-eastern and coastal Sindh with a little drizzle or light showers. However thunderstorm saga appears to be over and dreams of heavy monsoonal rainfall at the moment have vanished away.
You can read special monsoon article by Pakistan Weather Portal (PWP), here;
- Monsoon 2011 and Cyclones – Sub-continent’s coastal threat?-Part 3
- Monsoon and its Dangers – How many people will die this year?– Part4
- When will Monsoon start over Pakistan? – In Detail!-Part 5
- Monsoon 2011: Backlash of the floods? – History of Pakistan floods in Detail-Part 6
- Monsoon rain of July 28, 2010 – Dark day, but more was ahead!-Part 7
- Much awaited monsoon showers lashes Karachi!-Part 8
- Little girl may return for Monsoon: La-Nina episode!-Part 9
- Heavy downpour in Karachi!-Part 10