Case Study: Heavy Rainfall Event over Lai Nullah Catchment Area

Muhammad Afzal, Qamar ul Zaman


This research is an effort to understand the heavy rainfall phenomenon which gripped the upper area of Pakistan from 4–9 July 2008. This week lasting event created close to flood situation in Lai Nullah basin of Islamabad. The focus is mainly kept at flooding occurred in the Nullah on 5th July. This study was also an effort to effectively forecast the amount of precipitation expected as a result of such event so that flood like situation can be timely forecasted. The NCEP reanalysis (2.5° × 2.5°) data sets were utilized for this purpose. Different meteorological fields were used to get a picture of atmosphere. It also helped in comparison of both the observed and reanalysis data sets for one particular event. NCEP reanalysis data set though of coarse resolution presented good picture of event in terms of interaction between two main weather systems. The analysis revealed that the south-easterly incursion from the Arabian Sea was activated due to the westerly trough approaching the HKH mountain ranges. The results showed that Vertical wind Velocity (omega) and constant pressure surfaces are good predictors for this particular study.

Full Text:



Anjum M. Akram, 2004: Tibetan Plateau and mechanism for Indo-Pak Monsoons’ Evolution, Pakistan Journal of Meteorology, vol.1 Issue:1.

Biswas, N.C., U.S. De and D.R. Sikka, 1998: The role of Himalayan massif – Tibetan Plateau and the mid-tropospheric tropical ridge over north India during the advance phase of the outhwest monsoon, Mausam, 49, 285-298.

Chaudhry, Q.Z., G. Rasul., 2007: Development of a mesoscale convective system over the foothills of Himalaya into a severe storm. Mountains witnesses of Global Changes, ELSEVIER, Ch.33, pp 301-311.

Climatic Normal of Pakistan (1971-2000), Climatic Data Processing Center (CDPC) Karachi, Published 2005, Pakistan Meteorological Department.

Ding Yihui, Fu Xiuqin and Zhang Baoyan, 1984: Study of the structure of a monsoon depression over the Bay of Bengal during summer MONEX. Advance Atmospheric Sciences,Vol.1(1), pp 62-75.

Das, Someshwar, S.V. Singh, E.N. Rajagopal and R. Gall, 2003: Mesoscale modeling for mountain weather forecasting over the Himalayas. Bulletin of the American Meteorological Society, Vol. 84, no. 9, pp 1237-1244.

Kamal Ahmed, 2004. Pakistan: Lai Nullah basin flood problem Islamabad – Rawalpindi cities WMO/GWPAssociated Programme on Flood Management.

Khan, J.A. 1993. The Climate of Pakistan. Rehbar Publishers, Karachi.

Krishnamurti, T. N., 1971: Observational study of the tropical upper tropospheric motion field during the northern hemispheric summer. J. Appl. Meteor., 10, 1066–1096.

Krishnamurti, T. N., and T. Murakami, 1981: On the onset vortex of the summer Monsoon. Mon. Wea. Rev.,109, 344–363.c

Rasul, G., Q. Z. Chaudhary, S.X. Zhao and Q.C Zeng, 2004: A Diagnostic study of record heavy rain in twin cities Islamabad-Rawalpindi, Advances in Atmospheric Sciences, 21, pp. 976-988.

Rasul, G., Q. Z. Chaudhry, Z. Sixiong, Z. Qingcum, QI. Linlin, and Z. Gaoying, 2005. A Diagnostic Study of Heavy rainfall in Karachi Due to Merging of a Mesoscale Low and a Diffused Tropical depression during South Asian Summer Monsoon. Advances in Atmospheric Sciences, Vol. 22, No. 3, 2005, 375-391.

Rao, Y. P., V. Srinivasan, and S. Raman, 1970: Effect of middle latitude westerly systems on Indian Monsoon Syp. Trop. Met. Hawaii. No. IV 1-4.

Shamshad, K.M., Published 1988. The Meteorology of Pakistan, First Edition, Royal Book Company Publishers, Karachi.


  • There are currently no refbacks.