Khan, Azmat Hayat*

On 28th March, 2001 (1530LT), a tornado produced surface winds greater than 65 kts in Chak Misran village near Bhalwal area. This storm was much stronger-appearing on radar compared to a sqall-line of intense storms during late winter season. This paper documents the structure of this storm, as reflected by charts and visualized by satellite data.

Synoptic History:

March is the peak month of spring season and sufficient isolation towards end of month combined with polar continental air over upper parts of country results high degree of instability and produce violent thunderstorms.

Satellite picture of 04 Z & pressure pattern at 0600z on 28th March, 2001		On 28th March, at 0500PST, continental air was penetrating into northern half of country. Also there was sufficient moisture influx from Arabian Sea upto 18000 ft.  Right from surface to 18000 ft,  charts depicted some what intense circulation over central Punjab with centre near Sargodha area that acted as a vortex of southwest relatively warm-moist currents and cold continental air from north-northwest.
850 mb pressure pattern at 0500PST  on 28th March, 2001	Consequently a squall line of thunderstorms developed. A number of stations in north Punjab and upper NWFP including Lahore, Sargodha, Rawalpindi , Peshawar reported thundershowers in METARS. The vortex formation was further accentuated as the day progressed and moist atmosphere absorbed maximum energy.

    Vortex formation further intensified during afternoon as is evident from the 1200Z chart at 850 mb & satellite imagery of 0900Z.

850 mb analysis at 12Z on 28/3/01

Satellite imagery at 09Z- 28/3/01

500mb analysis at 00Z on 28/3/01

Classification of 28th march Storm:

• As per eyewitnesses reports, wind storm associated with hailstorm started at 1525 PST. Within next five minutes, cloud-base seemed to touch the ground and destructed building structure, very heavy equipment and uprooted steel electric poles.

• Some electric poles were found imbedded half their length into the ground quite far from their original locations. This reflects that poles were carried aloft quite high.

• The pattern of destruction on ground suggest that the severe effects of winds were initially from east/southeast towards west/northwest and then from west towards east/southeast. It suggest the whirling of storm/development of pressure nose.

• Also, notice the rotary damage pattern of machinary. Wind whirl pulled up heavy equipment like tractor trolleys and wheat thrasher in a pattern showing the spinning motion of the air and thrown far away from their original locations.

• Loss of 10 lives with human and animal dead bodies & their dismembered parts dispersed quite far off. Also injuries to more than 100 persons due to flying debris. It is somewhat a clear indicator that this destruction was an outcome of tornado.

• A number of building structures and equipment in the vicinity of affected area, remained intact.

File photo of heavy equipment like tractor trolley and wheat thrasher that were thrown far away by the suction vortex/tornado on 28th March, 2001

Conclusion:

Tornadoes come from the energy released in a thunderstorm. What makes them dangerous is that their energy is concentrated in a small area, perhaps only few hundred yards across. They occur mostly during the spring and summer. They usually occur during the late afternoon and early evening.

The size of area affected by the storm and damage pattern on 28th March, 2001 in Chak Misran suggest that strong convergence of winds(tornado) caused the instantaneous destruction in the village.

* Author of this article is Meteorologist in Pakistan Meteorological Department engauged in operational research.