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Effect of latent heating on mesoscale vortex development during extreme precipitation: Colorado, September 2013

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dc.contributor.authorMorales, Annareli, author
dc.contributor.authorKreidenweis, Sonia M., advisor
dc.contributor.authorSchumacher, Russ S., advisor
dc.contributor.authorRamirez, Jorge A., committee member
dc.date.accessioned2007-01-03T06:23:20Z
dc.date.available2007-01-03T06:23:20Z
dc.date.issued2014
dc.description.abstractFrom 9-16 September 2013, a slow-moving cut-off low in the southwestern U.S. funneled unseasonal amounts of moisture to the Colorado Front Range, resulting in extreme precipitation and flooding. The heaviest precipitation during the September 2013 event occurred over the northern Colorado Front Range, producing a 7-day total of over 380 mm of rain. The flash flooding caused over $3 billion in damage to property and infrastructure and resulted in eight fatalities. This study will focus on the precipitation and mesoscale features during 11-12 September 2013 in Boulder, CO. During the evening of 11 September, Boulder experienced flash flooding as a result of high rain rates accumulating over 180 mm of rain in 6 hours. From 0400-0700 UTC 12 September, a mesoscale vortex (mesovortex) was observed to travel northwestward towards Boulder. This circulation enhanced upslope flow and was associated with localized deep convection. The mesovortex originated in an area common for the development of a lee vortex known as the Denver Cyclone. We hypothesize that this mesoscale vortex is not associated with lee vortex formation, such as the Denver Cyclone, but developed through the release of latent heat from microphysical process. The Advanced Research Weather Research and Forecast (ARW) model was used to 1) produce a control simulation that properly represented the evolution and processes of interest during the event and 2) test the importance of latent heating to the development and evolution of the mesovortex. The results from various latent heating experiments suggested that the mesovortex did not develop through lee vortex formation and the latent heat released just before and during the mesovortex event was important to its development. Results also showed latent heating affected the flow field, resulting in a positive feedback between the circulation, associated low-level jet, and convection leading to further upslope flow and precipitation development. Further experiments showed condensation of cloud water was the dominant microphysical process responsible for a positive vertical gradient in latent heating near the surface. This gradient led to potential vorticity generation; a similar mechanism to that of a mesoscale convective vortex, except closer to the surface. Finally, an experiment where the latent heating was reduced by half after 1800 UTC 11 September resulted in no mesovortex development and a substantial decrease in precipitation. The results from this study have relevant implications to the representation of microphysical processes in numerical weather prediction models. The capability to forecast the development of these mesovortices and their subsequent environmental and hydrological effects could be critical for decision makers and the public, given their association with high rain fall rates.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierMorales_colostate_0053N_12648.pdf
dc.identifier.urihttp://hdl.handle.net/10217/88580
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationwwdl
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectpotential vorticity
dc.subjectColorado Flood
dc.subjectextreme precipitation
dc.subjectlatent heating
dc.subjectmesoscale vortex
dc.titleEffect of latent heating on mesoscale vortex development during extreme precipitation: Colorado, September 2013
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineAtmospheric Science
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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