Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 14, 3331-3344, 2014
https://doi.org/10.5194/nhess-14-3331-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
19 Dec 2014
Numerical simulation of a rare winter hailstorm event over Delhi, India on 17 January 2013
A. Chevuturi1, A. P. Dimri1, and U. B. Gunturu2 1School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
2King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
Abstract. This study analyzes the cause of the rare occurrence of a winter hailstorm over New Delhi/NCR (National Capital Region), India. The absence of increased surface temperature or low level of moisture incursion during winter cannot generate the deep convection required for sustaining a hailstorm. Consequently, NCR shows very few cases of hailstorms in the months of December-January-February, making the winter hail formation a question of interest. For this study, a recent winter hailstorm event on 17 January 2013 (16:00–18:00 UTC) occurring over NCR is investigated. The storm is simulated using the Weather Research and Forecasting (WRF) model with the Goddard Cumulus Ensemble (GCE) microphysics scheme with two different options: hail and graupel. The aim of the study is to understand and describe the cause of hailstorm event during over NCR with a comparative analysis of the two options of GCE microphysics. Upon evaluating the model simulations, it is observed that the hail option shows a more similar precipitation intensity with the Tropical Rainfall Measuring Mission (TRMM) observation than the graupel option does, and it is able to simulate hail precipitation. Using the model-simulated output with the hail option; detailed investigation on understanding the dynamics of hailstorm is performed. The analysis based on a numerical simulation suggests that the deep instability in the atmospheric column led to the formation of hailstones as the cloud formation reached up to the glaciated zone promoting ice nucleation. In winters, such instability conditions rarely form due to low level available potential energy and moisture incursion along with upper level baroclinic instability due to the presence of a western disturbance (WD). Such rare positioning is found to be lowering the tropopause with increased temperature gradient, leading to winter hailstorm formation.

Citation: Chevuturi, A., Dimri, A. P., and Gunturu, U. B.: Numerical simulation of a rare winter hailstorm event over Delhi, India on 17 January 2013, Nat. Hazards Earth Syst. Sci., 14, 3331-3344, https://doi.org/10.5194/nhess-14-3331-2014, 2014.
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Short summary
This study analyzes the cause of the rare occurrence of a winter hailstorm over New Delhi/NCR (National Capital Region), India. The absence of increased surface temperature or a low level of moisture incursion during winter cannot generate the deep convection required to sustain a hailstorm. Consequently, NCR shows very few cases of hailstorms in the months of December-January-February, making the winter hail formation a question of interest.
This study analyzes the cause of the rare occurrence of a winter hailstorm over New Delhi/NCR...
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