A fresh western disturbance is expected to affect the parts of country that is likely to break the hot spells that started during last week of April. No Pre-monsoon activity is expected in the country neither in the southern parts nor the northern parts till the end of May.
Summer season – Western Disturbance in Pakistan
A total of four western disturbance has affected the country since the beginning of summer season (April). Only three waves occurred in the month of April while the forth had started affecting the country on May 5 night.
- Western Disturbance 01, the first Western Disturbance of summer season, which PWP named as ”01″ reached the country on April 9 and remained so till April 14. Rainfall occurred in Islamabad on April 8, heavy rainfall in Murree on April 14. While unusual light hailstorm occurred in the southern city of Hyderabad on April 12. Drizzle occurred in Lahore on April 13.
- Western Disturbance 02 was a large storm with cyclonic circulations at the centre of the storm. The wave had gust fronts as well. WD 02 entered west-central Balochistan including Quetta on April 17. It caused a coastal thunderstorm to form near southern Pakistan that killed 6 people in Oman, it caused rainfall (5 mm) on April 19 in Karachi with strong winds (60 km/h) and Makran coast. WD 02 caused countrywide rainfall with varying intensity. It caused a Microburst on April 20 near Islamabad that caused Bhoja airline to crash, same day sharp showers (8 mm) occurred in Islamabad with fast winds (68 km/h). On April 20, it caused isolated shower in the upper parts of Sindh. It caused showers with gale-force winds in Gujranwala on April 22 night. On April 23, it was over northern Pakistan and adjoining however it caused some more showers in upper Sindh on April 23 evening. On April 24, it moved into India and started its affect over adjoining Nepal as well. Size wise, Length wise, effect wise and duration wise, Western disturbance 02 has been the most strongest western wave since 2011-2012 winter season.
- Western Disturbance 03, entered Pakistan on April 27 and moved away on May 2, it was a feeble western disturbance and did not cause much significant rainfall.
WD 04: Another rainy week?
Western disturbance 04 persisted over extreme northern Afghanistan on May 5 night, its trough entered north-west Pakistan on May 5, showers with gale-force winds lashed Banu that brought billboards down, injuring 3 people. Low lying clouds on May 5 night blocked the supermoon in Karachi.
This new disturbance has the strength of being weak and it would influence the country for this current week. Due to moisture incursion and temperature variations, chances of drizzle/isolated shower with fast winds may occur over various parts of the country including upper Sindh from May 7 night/May 8 evening; mainly from a local formation of a thunderstorm.
Middle week forecast
During the middle of this week, there are chances of moderate showers with fast/strong winds in Punjab, Khyber, north-western Balochistan and upper Sindh. Karachi is likely to witness passing clouds with windy conditions, keeping the temperatures calm however during the middle of this week a thundercloud would form just north of the city that could affect Hyderabad and south-eastern Sindh.
According to Pakistan Weather Portal (PWP) local stray thundercloud would continue to affect parts of Sindh and central Balochistan till mid of May while westerlies could increase their activity over northern Pakistan.
Monsoon 2012 Update
Western Disturbance vs Monsoon
Seasonal heating halted again
Tropical Activity in the Bay of Bengal and Arabian sea?
This is not normal!
May is famous all over the country as it is considered as a scorching heat month. Western Disturbance is mainly a winter precipitation system but during the summer months it is mostly fueled by the local heat of the sub-continent that makes them stronger to carry moisture as far as Nepal. Though these waves do affect northern Pakistan in the month of May but influencing Sindh including Karachi is very rare. Once the western disturbance starts affecting Pakistan, the seasonal heating would again halt which would be a huge setback for the monsoon season. The heat generating system was also affected in April by Western Disturbance 02.
Tropical Activity – Pakistan Weather Portal (PWP) Poll
American models indicate that during the end of May, tropical disturbance might form in the Bay of Bengal that would move in a NNE. While a well-marked low pressure could form in the east-central Arabian sea which is likely to die out in the open sea waters.
But European and Canadian models does not suggest anything brewing in either of the seas till the end of May.