Woodhams, BJ orcid.org/0000-0003-2070-8279, Birch, CE orcid.org/0000-0001-9384-2810, Marsham, JH orcid.org/0000-0003-3219-8472 et al. (3 more authors) (2019) Identifying key controls on storm formation over the Lake Victoria Basin. Monthly Weather Review, 147 (9). pp. 3365-3390. ISSN 0027-0644
Abstract
The Lake Victoria region in East Africa is a hotspot for intense convective storms that are responsible for the deaths of thousands of fisherman each year. The processes responsible for the initiation, development and propagation of the storms are poorly understood and forecast skill is limited. Key processes for the lifecycle of two storms are investigated using Met Office Unified Model convection-permitting simulations with 1.5 km horizontal gridspacing. The two cases are analysed alongside a simulation of a period with no storms to assess the roles of the lake–land breeze, downslope mountain winds, prevailing large-scale winds and moisture availability. Whilst seasonal changes in large-scale moisture availability play a key role in storm development, the lake–land breeze circulation is a major control on the initiation location, timing and propagation of convection. In the dry season, opposing offshore winds form a bulge of moist air above the lake surface overnight that extends from the surface to ~1.5 km and may trigger storms in high CAPE/low CIN environments. Such a feature has not been explicitly observed or modelled in previous literature. Storms over land on the preceding day are shown to alter the local atmospheric moisture and circulation to promote storm formation over the lake. The variety of initiation processes and differing characteristics of just two storms analysed here show that the mean diurnal cycle over Lake Victoria alone is inadequate to fully understand storm formation. Knowledge of daily changes in local-scale moisture variability and circulations are key for skilful forecasts over the lake.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 American Meteorological Society (AMS). This article is licensed under a Creative Commons Attribution 4.0 license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | Lake Victoria; tropical; lake breeze; land breeze; convection; East Africa; lake |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number NERC NE/M02038X/1 NERC NE/P021077/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 02 Jul 2019 12:32 |
Last Modified: | 25 Jun 2023 21:53 |
Status: | Published |
Publisher: | American Meteorological Society |
Identification Number: | 10.1175/MWR-D-19-0069.1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:148027 |