The initiation and maintenance of convection along synoptically-quiescent drylines
Katherine L. Horgan, Texas Tech University, Lubbock, TX; and C. C. Weiss
Convection occurs across the majority of the United States, yet the forecasting of where and when that convection will form and if it will sustain itself is still not well understood. The dryline features highly variable vertical velocity along its length, presenting a particular convection initiation challenge for forecasters over the Plains. Schaefer (1986) found that 70% of the dryline days in April, May, and June were convectively active. Convection associated with the dryline accounts for a large amount of the total rainfall over the area in the spring and summertime. Dryline convection is also typically associated with severe weather and therefore the forecasting of convection initiation (CI) is of particular importance to public safety. This study aims to give forecasters a better understanding of how convection initiates and sustains itself along the dryline.
The first phase of this study uses the Advanced Research Weather Research and Forecasting (ARW) Model to study the dryline from an idealized sense. A control simulation was constructed on a 900 x 450 km domain using a hyperbolic terrain profile similar to the one actually observed across the Caprock in West Texas. Sensitivity studies were run by varying temperature, wind, and moisture variables at multiple levels in the initialization. Soil and vegetative gradients were also varied to determine the impact on the dryline circulation. The results from the sensitivity runs will be presented and related to previous findings. Preliminary conclusions regarding the effects of the dryline on convective initiation and sustenance will be offered.
Poster Session 1, Student Conference General Poster Session
Sunday, 20 January 2008, 5:30 PM-7:00 PM, Exhibit Hall B
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