A Numerical Study of the June 2013 Flood-Producing Extreme Rainstorm over Southern Alberta

A devastating, flood-producing rainstorm occurred over southern Alberta, Canada, from 19 to 22 June 2013. The long-lived, heavy rainfall event was a result of complex interplays between topographic, synoptic, and convective processes that rendered an accurate simulation of this event a challenging t...

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Bibliographic Details
Published in:Journal of hydrometeorology 2017-08, Vol.18 (8), p.2057
Main Authors: Li, Yanping, Szeto, Kit, Stewart, Ronald E, Thériault, Julie M, Chen, Liang, Kochtubajda, Bohdan, Liu, Anthony, Boodoo, Sudesh, Goodson, Ron, Mooney, Curtis, Kurkute, Sopan
Format: Article
Language:English
Subjects:
Atmospheric precipitations
Atmospheric sciences
Climate change
Computer simulation
Convective activity
Evaporation
Evapotranspiration
Extreme weather
Floods
Heavy rainfall
Laboratories
Mathematical models
Microphysics
Physics
Plains
Prairies
Precipitation
Rain
Rainfall
Regional analysis
Sensitivity analysis
Simulation
Soil
Soil moisture
Trajectory analysis
Uptake
Water budget
Water resources
Weather forecasting
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Summary:A devastating, flood-producing rainstorm occurred over southern Alberta, Canada, from 19 to 22 June 2013. The long-lived, heavy rainfall event was a result of complex interplays between topographic, synoptic, and convective processes that rendered an accurate simulation of this event a challenging task. In this study, the Weather Research and Forecasting (WRF) Model was used to simulate this event and was validated against several observation datasets. Both the timing and location of the model precipitation agree closely with the observations, indicating that the WRF Model is capable of reproducing this type of severe event. Sensitivity tests with different microphysics schemes were conducted and evaluated using equitable threat and bias frequency scores. The WRF double-moment 6-class microphysics scheme (WDM6) generally performed better when compared with other schemes. The application of a conventional convective/stratiform separation algorithm shows that convective activity was dominant during the early stages, then evolved into predominantly stratiform precipitation later in the event. The HYSPLIT back-trajectory analysis and regional water budget assessments using WRF simulation output suggest that the moisture for the precipitation was mainly from recycling antecedent soil moisture through evaporation and evapotranspiration over the Canadian Prairies and the U.S. Great Plains. This analysis also shows that a small fraction of the moisture can be traced back to the northeastern Pacific, and direct uptake from the Gulf of Mexico was not a significant source in this event.
ISSN:1525-755X
1525-7541
DOI:10.1175/JHM-D-15-0176.1">