Lahore has its first heavy monsoon downpour on August 4th, 2012. It is late by almost four weeks. It was being forecasted almost every day, but somehow it withheld. More than 20 million people felt the heat of waiting for this pleasant gift of God.
Like the Lahore example, weather forecasting is almost a challenging task and thus we cannot predict it beyond a certain level.
Weather forecasting has never been easy in spite of modern tools and latest software on tap with meteorological department. Real time and periodic satellite pictures are easily accessible. Cloud formation, size, direction and other details are also handy.
Other factors such as Wind direction, Atmospheric pressure, Temperature, Humidity, Vapour density etc are all the time tabulated locally, as well as regionally.
Still, we fell poorly short to understand the mechanism on which serious forecasting for the area is based.
Weather predictions and forecasting in respect of the populated areas of Punjab, including Lahore and its surroundings in particular are seen to be clearly off-targeted. The erratic behavior of monsoon weather at the start is pronounced, and kept people wondering about why there is such a drastic weather shift this year.
Met office high ups appear uninterested to actually get out of the rut and accept their shortcomings in understanding and correcting the erratic forecasting.
It would have been much better if the general lot were regularly kept informed as to why the extra-humid cum hot period had penetrated deep into the monsoon phase after the usual pre-monsoon humid period and made more probabilistic forecasting difficult.
Lahore did have a few random messy drizzles earlier through stray clouds in part of the city and the adjoining areas, but of little consequence. The ensuing oppressive and suffocating weather added to the misery of people who are already facing power shortage.
Before delving deeper into the phenomenon, it is necessary to overview briefly the back ground information.
The normal path of monsoon clouds is Bengal, Bihar, UP, East Punjab, Punjab and KP. Within this path, there are air currents bringing clouds from east as well as from north-east. Focusing on the clouds coming towards Lahore, the bulk moves west ward. Beyond New Delhi, the region is well populated and demographic changes have slowly influenced the amount of rainfall. Average annual rainfall for New Delhi is 28 inches (less than 30 inches a few decades earlier). Likewise, Lahore has less than 22 inches although earlier the average used to be 23 inches plus. Barring last year’s rainfall (60 inches plus because of the probable jet stream phenomenon driving very thick wide spread multi-layered clouds), Lahore has been observing a decline in annual rainfall figures and monsoon figures on average.
The reasons can be attributed to tree cutting, pollution, reflective heat and radiation from the roads and built areas etc. The same argument holds good for Kasur, Gujranwala, Faisalabad and other places adjacent to Lahore.
The other important reason is the near-ground composite temperature coupled with the thinning of clouds along their monsoon route beyond a critical point of crystal/vapour-temperature balance in the clouds above the vicinity, west-ward near New Delhi. It is opined that rice fields also are the cause of the humidity; yes, but only to a limited extent.
The rise in the night-time minimum temperature of the urbanised areas, over a long period of time, provides sufficient residual heat to continually aggravate the situation. Minimum temperatures of New Delhi and Lahore have significantly risen over past few decades. Thus, thinning clouds steadily lose their contents to atmospheric haziness as moisture is sucked downward mainly through the convection process and seeding on the pollutants. It gives rise to the relative humidity and at the same time a drop in the average rainfall figures. This has been happening for the last many years and is likely to continue as such unless effective steps for the reversal of situation are taken.
Thus, the challenge for city planners is to take measures so that rain comes down with higher probability despite lesser water content, with lower probability for it to be converted to the atmospheric haziness due to suspended vapours. Cloud images repeatedly show this story beyond New Delhi; clouds grow smaller as they progress along the monsoon path. The whitish haze has been quite visible even beyond Faisalabad.
Tree planting is the main requirement in our country besides other innovative techniques to make the best of available solar energy in the form of heat and light. Our figures for forestation are close to 4 per cent, and Lahore and its surrounding areas may not be far from that. The figures should be raised four to five times to improve upon the average annual rainfall with other added benefits e.g., steady lowering of peak temperatures in summer in the coming years.
The Punjab government must act to overcome this rapidly changing scenario.