Synoptic Study of The 2015 Flash Floods in Chitral Area, Northern, Pakistan

Abstract

The weather patterns of whole world have changed over last five decades as depicted by analysis of the past. This research has diagnosed the atmospheric parameters that resulted in the extreme flood events in the northern areas of Pakistan especially over Chitral valley from 15th to 28th July, 2015 by utilizing observed data as well as National Centre for Environmental Protection and National Centre for Atmospheric Research reanalysis data. Analysis has revealed that the geopotential height and temperature contours at 200hpa indicated strong differential development which resulted in protraction of jet stream trough over Chitral valley. Easterly moisture interacted with the westerly moisture contributing to 80% relative humidity causing heavy down pour. Persistence of heat wave over a week prior to the rain spell gave way to the development of low pressure cells over Chitral valley. Heavy precipitation was also recorded prior to the flash flood episode taken under the study which was 8.4 mm on 18h July. Another reason of rainfall was the presence of warm temperature conditions at the surface, leading to positive omega values on 28n July. The sagacious and discreet analysis of the NCEP (National Centre for Environmental Protection) simulations along with synoptic conditions and available data at Pakistan Meteorological Department reveals that the entire interaction led to the development of low pressure system over Northern areas, bringing about rain spell and floods. In addition, regional projection of future temperature and precipitation trends over Chitral valley by the end of this century portrays that these variables will intensify with each passing decade.