“This is the fifth special monsoon article of 2011 and it will follow many more monsoon article”
Monsoon to begin during the first week of July in Pakistan
Monsoon season is the annual rainy season in Pakistan. The country depends heavily on these monsoon for its agricultural and water needs. The south-west monsoons roars onto the subcontinent during the summer. The winds carry moisture from the Indian Ocean and bring heavy rains from June to September. The torrential rainstorms often cause violent landslides. Entire villages swept away during monsoon rains. Despite the potential for destruction, the summer monsoons are welcomed in Pakistan. Farmers depend on the rains to irrigate their land. Additionally, a great deal of Pakistan’s electricity is generated by water power provided by the monsoon rains.
When will monsoon reach Pakistan in 2011?
Pakistan is lashed by the rains from July to September from the South-west monsoon. This monsoon reaches Pakistan towards the beginning of July and establishes itself by the middle of the month. The strength of the monsoon current increases from June to July; it then remains steady, and starts retreating towards the end of August, though occasionally, it continues to be active even in September when some of the highest floods of the Indus Basin have been recorded. After September the monsoon withdraws from the country. But tropical activity could occur before and after the monsoon, mainly in May till June and then in September till October. Certain events like El-Nino, La-Nina, +IOD or -IOD have major effect on the timing and intensity of the monsoon.
The monsoon of 2011 is expected to advance into the South and Central Bay Islands, Bay of Bengal around the 16th of May. While the monsoon may reach Maldives during the end of May, so the monsoon moisture from the Arabian sea and Bay of Bengal will start reaching Pakistan from the first week of July, little delay or a little earlier advancement can not be ruled out. Punjab and some parts of Khyber could get pre-monsoon showers due to the interaction of western disturbance and weak monsoon moisture from Arabian sea. When did previous monsoons of 2009 and 2010 entered Pakistan?, lets take a look;
Monsoon of 2009
During this year most of Pakistan was going through El-Nino that caused 30% below normal rainfall.
Condition affecting this monsoon
Overall, 9 weather system affected Pakistan during the monsoon of 2009, the Sindh province was the most wettest region of the country as 5 weather system affected the province. While Punjab, Khyber and Kashmir received weak moisture from the Bay of Bengal and Arabian sea, which interacted with the western disturbances. Baluchistan, FATA, Gilgit and parts of Khyber province received drizzle to light rainfall during this period as they are outside the monsoon zone. Karachi got 439.2 mm during the monsoon of 2009 while the average is just 146.4 mm.
June – Pre monsoon
Pre-monsoon activity was observed in Sindh including Karachi due to the formation of weak tropical depression ARB 01 in the Arabian sea on June 23. The storm caused light rainfall with gusty winds in the coastal belt. 3 mm rainfall was recorded in Karachi due to this depression. On June 25, the remnants of ARB 01 helped the formation of another weak tropical depression ARB 02 which was just 300 km away from Karachi, it however caused strong winds in the coastal Sindh. No pre-monsoon activity occurred in upper parts of the country, western disturbance (non-monsoon weather system) however caused rainfall in those areas.
The first proper monsoon rainfall of Pakistan occurred on July 18 in Sindh province, this low pressure caused record-breaking rainfall of 245 mm in Karachi in just 4 hours on the night of July 18, this low developed as a tropical depression in the Bay of Bengal on July 14 and moved in a west-north-west direction, then started losing its strength and turned into well-marked low on 15 July after crossing Madhya Pradesh (India) it finally reached over Southeastern parts of Rajasthan (India) on July 18 as a low pressure. It moved continuously in the same direction and reached over Sindh on 19 July, 2009 where the torrential rains were recorded which caused urban flooding in the area especially Karachi and Hyderabad.
The second monsoon system developed over northwest Bay of Bengal on July 20 which again intensified into a tropical depression on July 21, it also moved in the same direction as the previous one did, it however weakened quickly and reached the southern parts of Rajasthan on July 24 and from here it moved further towards Sindh where it later on dissipated. Due to this weather system moderate rains with isolated heavy falls with strong winds were observed over coastal & Southeastern parts of Sindh. Karachi received 18 mm rainfall from this system.
During the month of August only one monsoon system developed in the Bay of Bengal on August 27, this weather system initially moved rapidly in a northwesterly direction and reached over southeast Madhya Pradesh (India) on July 28. After moving west northwestward it reached Rajasthan on July 29 and weakened gradually. Under its influence moderate to heavy rainfalls were recorded over southeast Sindh. In Karachi, this well-marked low pressure caused 147 mm rainfall on August 31.
During the month of September, only one monsoon low originated from North Bay of Bengal, on September 5, which took a west north-westerly course till it reached over northern parts of Madhya Pradesh on September 10. From here it moved north-north-eastwards and dissipated without affecting Pakistan.
November – Post monsoon
On November 4, a low pressure formed in the Arabian sea and on November 7, it intensified into cyclone “Phyan”(tropical storm on SSHS). The cyclone had 50 mph winds as it battered Mumbai and Indian state of Gujarat. The storm caused dusty winds in the coastal parts of Sindh. However six Pakistani fishermen were trapped in the storm later rescued by the Indian Navy.
Monsoon of 2010
In 2010, Pakistan saw its worst flooding in its living memory. Wet conditions prevailed in Sindh till September and then again in November. Karachi got 741.9 mm during this monsoon, while the average is just 146.4 mm.
Condition affecting this monsoon
June – Pre monsoon
On June 2, a strong tropical storm “Phet” in the Arabian sea intensified into a category-4 hurricane. Cyclone caused heavy rainfall with fast to strong winds over Sindh province on June 6 and June 7. Karachi got 152 mm rainfall during this period. On June 14, some pre-monsoon currents from the Arabian sea caused light rainfall with strong winds in Punjab.
On July 5, a monsoon low pressure approached Sindh through the Indian state of Gujarat and caused moderate rainfall till July 7. During this period a total of 57.5 mm rainfall was recorded in Karachi. On July 23, an upper air cyclonic circulations caused heavy rainfall of 53mm in Karachi. Another low pressure from July 26 till July 28 caused heavy rainfall of 139 mm in Karachi. This monsoon system caused extreme rainfall in Punjab and Khyber that started the floods of 2010, the low pressure interacted with a string western disturbance over Gilgit.
From August 7 till August 9, at least 180 mm rainfall was recorded in Karachi with intense thunderstorms. This system enhanced the intensity of the floods. Moisture from Arabian sea caused 3.5 mm rainfall on August 15 in Karachi. August remained rainy in Punjab and Sindh, with some what daily drizzle in Karachi.
On September 1, 5 mm rainfall occurred in Karachi with fast winds as a low pressure was dissipating over Sindh that came from India. From September 9 till September 11, a very heavy rainfall with strong winds lashed Karachi and Sindh province, at least 150.6 mm rainfall was recorded during that period. Western disturbance affected Punjab after this system dissipated.
November- Post monsoon
On November 9, the remnants of Cyclone Jal that formed in the Bay of Bengal, reached Sindh-Gujarat coast after a long journey, the storm slightly intensified and caused light drizzle with dusty winds in Karachi and south-eastern Sindh. On November 23, a low pressure are formed near Sindh and Gujarat that caused drizzle in Karachi and adjoining areas of the city.
Monsoon of 2011?
Condition affecting this monsoon
- Weak La-Nina till June
- Weak Negative Indian Ocean Dipole (-IOD)
The onset of southwest monsoon over Kerala, India signals the arrival of monsoon over the Indian subcontinent and represents beginning of rainy season over this region. The monsoon first hits Kerala and then advances to other parts of the Indian subcontinent. Over the years the Indian Meteorological Department (IMD) forecasts the onset on monsoon over Kerala, which can be seen from the below data;
|Year||Actual Onset Date||Forecast Onset Date|
|2005||7th June||10th June|
|2006||26th May||30th May|
|2007||28th May||24th May|
|2008||31st May||29th May|
|2009||23rd May||26th May|
|2010||31st May||30th May|
The IMD has predicted that the monsoon will hit Kerala on May 31 (normal date), though there forecast changes in June but as of now they are firm on their earlier decision that is the monsoon will enter India on May 31.
Pre monsoon activity in India is likely to start between May 17 and May 20, under that influence heavy rainfall are forecasted in Kerala and other adjoining areas. These rains will be isolated but after May 31 they might become scattered. These factors should happen because if they fail to reach India on time, the monsoon will then definitely reach Pakistan late.
When will Monsoon start over Karachi?
The monsoon generally reaches Pakistan during the first week of July while Karachi gets hit by monsoon during the second week of July that is till July 7. Following are the dates of monsoon onset in Karachi during the last few years;
In 2007, Proper monsoon rains started from July 1, 6-days earlier. Heavy Pre-monsoon activity was observed all over June in Karachi.
In 2008, proper monsoon rains started from 29 July, 22-days delay. No pre-monsoon activity was observed in Karachi.
In 2009, Proper monsoon rains started from July 18, a 10-days delay. Pre-monsoon activity was observed in June in Karachi.
In 2010, Proper monsoon rains reached Karachi on July 5, 2-days earlier. Pre-Monsoon activity was observed in late May and early June.
Cyclones usually strike between May and June before the onset of the monsoon, or between October and November, just after it ends. Once the monsoon clouds set in that July and August, they prevent cyclones from developing beyond the initial stage of a deep depression (tropical depression).
Monsoon could reach Karachi between mid-July. But there is no chance of pre-monsoon activity in Karachi as of yet! So keep your umbrella, emergency, help line, generators ready Karachiites to avoid any uncertain incident, as monsoon is just around the corner.
Monsoon articles of 2011
you can read previous 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