Post drought: Monsoon broke silence over Karachi!

 “This is the seventh article related to the monsoon season of 2012 and it will be followed by the last article”

September 6 – Extremely Low lying clouds in Karachi

The monsoon season came to an unhappy ending but at the last moment it realized that it had forgot to pour in Karachi. The mega metropolis had remained largely dry since the beginning of July along with the province of Sindh that had been experiencing moderate version of drought during the rainy season. The drought caused a deadly viral infection in peacocks and some other life stocks; more than 200 peacock died in Sindh.

On September 5, almost every part of Karachi experienced heavy downpour that came in the city after a year. It is worth mentioning that since 2010, it has been rainy heavyily in September, a pattern not so common.

Timeline of the rain

On September 4 night, light to moderate shower occurred in few parts of Karachi with thunder/lightning and continued till 7:55 am PKT the next day. The rainfall was recorded was 4 mm.

On September 5, the day started with high level clouds coming from northern side while the temperature reached 38 °C at 1:30 pm PKT and after some tome drizzle started in parts of the city and after some hours heavy showers started lashing almost every part of the city that continued till 5:00 pm PKT with occassional gaps as the wind pattern changed from south-east to north-west. Following are the main factors of the day;

  • Quantity of rain – 41 mm
  • Wind direction – NW/SE: both remained active
  • Highest temperature – 38 °C
  • Highest humidity – 84%
  • Lowest pressure –  1001 hPa

Thunderstorms dissipating on September 5

September 6 was a dry day with humid days and scorching heat. During the day, winds mostly blew from North or North-east as the day progressed further dark black clouds were visible over the eastern sky of the city at about 5:00 pm PKT. Soon after 5:00 pm, thundershowers started in parts of the city with fast winds that continued intermittently with short gaps till night. The rainfall recorded on September 6 was the heaviest during this spell. Following are the main factors of the day;

  • Quantity of rain – 65 mm
  • Wind direction – NW/NE: both remained active
  • Highest temperature – 36 °C
  • Highest humidity – 94%
  • Lowest pressure –  999 hPa

On September 7 early morning, isolated moderate shower occurred in few parts of the city that lasted till few minutes after that sky started clearing up. However most of the day was dry and hot with warm northerly winds. Following are the main factors of the day;

  • Quantity of rain – 4.7 mm
  • Wind direction – NW/NE: both remained active
  • Highest temperature – 37 °C
  • Highest humidity – 89%
  • Lowest pressure –  999 hPa

On September 8 morning, showers with moderate falls were recorded in many parts of the city that last till few hours and after that sky was mostly cloudy with sunny intervals. After 5:55 pm PKT, another wave of showers started in the city. Following are the main factors of the day;

  • Quantity of rain – N/A
  • Wind direction – NW/N: both remained active
  • Highest temperature – 38 °C
  • Highest humidity – 94%
  • Lowest pressure –  999 hPa

The rains continued the next week as well, parts of the city experienced isolated heavy rainfall with strong thunder/lightning at times very strong on September 11 and September 12. Overall comparing it with the past monsoon years, the rains of 2012 were isolated in nature and their intensity was weak.

Who is responsible for the rain?

Trees under overcast conditions

There were two weather systems that were close to Sindh;

  1. An upper air cyclonic circulation was over northern Arabian sea and adjoining Gujarat and Sindh. On August 27, this weather system formed over northern Rajasthan and it moved southwards in the coming days. It is expected to intensify into a minimum level low pressure area on September 6 and move westwards before finally dissipating. On September 6, it intensified into a low pressure area and caused thunderstorm formation over coastal parts of Sindh, it weakened into an UAC on September 8 morning.
  2. A well-marked low pressure area was over East Madya Pradesh and adjoining area. Pakistan Weather Portal (PWP) first mentioned the formation of  this low pressure on September 2 and it formed on September 3 during the same day, PWP said that it might intensify during its lifetime and the low pressure intensified into a severe low pressure on September 4. On September 6, it weakened into a low pressure and moved westward/WNW and brought heavy downpour to eastern parts of Pakistan.

Problems faced during the rainfall

 The bigger the city is, the bigger the problems are! therefore as soon as the first drop of rain fell many areas experienced prolonged power outages and some streets turned into rivers.

Monsoon Special articles for 2012

You can read special monsoon article by Pakistan Weather Portal (PWP), here;

TO BE CONTINUED……

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