Extreme Precipitation Observations During the 2019 MISO-BOB Field Campaign

Extreme Precipitation Observations During the 2019 MISO-BOB Field Campaign | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Extreme Precipitation Observations During the 2019 MISO-BOB Field Campaign Edgar Francisco Gonzalez, Jayesh Phadtare, Jaynise Pérez Valentín, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5582212/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 Apr, 2025 Read the published version in Climate Dynamics → Version 1 posted 5 You are reading this latest preprint version Abstract The 2019 MISO-BOB field campaign, conducted from 27 May to 31 July in the Bay of Bengal (BOB), focused on investigating tropical waves and intraseasonal oscillations (ISO). Two ocean cruises took place in June and July, complemented by ground-based observations in tropical islands - Sri Lanka, Maldives, and Seychelles. On 18 July, an extreme rainfall event occurred in Sri Lanka, with over 200 mm of precipitation recorded in the mountainous Nuwara Eliya district ( \(\sim\) 1900 m above mean sea level), while coastal stations experienced minimal rainfall. Concurrently, gale-force westerly winds exceeding 60 km/hr were observed in Colombo, a low-elevation coastal city in the Western Province. This event was associated with a Convectively Coupled Kelvin Wave (CCKW) embedded within an eastward-moving ISO envelope over the Indian Ocean. The sharp contrast in rainfall between mountains and coast highlights the influence of elevated terrain on precipitation distribution. The role of orographic uplifting was studied using field data from sonic anemometers, radiosondes, Doppler Lidar, and rain gauges; the satellite-based rainfall estimates did not capture the intense orographic rainfall. During the event, the Froude number of the onshore flow was greater than 1 suggesting an unblocked flow over the coast transporting moisture toward the mountains; the level of free convection (LFC) was below the mountain peak. Thus, mechanical uplifting of conditionally unstable jet resulted in localized flooding over the mountain slopes. This case study supports the earlier idealized numerical experiments involving moist flow over orography and provides guidelines for forecasting extreme rainfall over the mountains of a tropical island. Convectively Coupled Kelvin Waves Monsoonal Precipitation Dynamics Tropical Atmosphere-Ocean Interaction Rainfall Variability in Sri Lanka Full Text Cite Share Download PDF Status: Published Journal Publication published 24 Apr, 2025 Read the published version in Climate Dynamics → Version 1 posted Editorial decision: Accept 06 Apr, 2025 Reviewers agreed at journal 29 Mar, 2025 Reviewers invited by journal 29 Mar, 2025 Editor assigned by journal 22 Mar, 2025 First submitted to journal 18 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5582212","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":435613240,"identity":"23c1f847-fba2-4335-929e-a0238dcae50b","order_by":0,"name":"Edgar Francisco 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