Dryline Characteristics near Lubbock, Texas, Based on Radar and West Texas Mesonet Data for May 2005 and May 2006

Bart Geerts University of Wyoming, Laramie, Wyoming

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Abstract

Two months of Lubbock, Texas, radar reflectivity data and West Texas Mesonet data are examined to detect dryline finelines and to describe their thermodynamic and propagation characteristics. Before sunset the moist air mass east of the dryline was consistently denser than the dry air mass. This air density difference waned and even reversed after sunset, because of more rapid cooling on the dry side.

This study provides further evidence that the formation and propagation of the dryline convergence zone is driven by the daytime air density difference, that is, that the dryline behaves as a density current. The implication for forecasters is that the air density (or virtual potential temperature) difference across the dryline should be monitored, as a measure of dryline strength and as an additional indicator for the likelihood of convective initiation along the dryline.

Corresponding author address: Bart Geerts, Dept. of Atmospheric Sciences, University of Wyoming, Laramie, WY 82071. Email: geerts@uwyo.edu

Abstract

Two months of Lubbock, Texas, radar reflectivity data and West Texas Mesonet data are examined to detect dryline finelines and to describe their thermodynamic and propagation characteristics. Before sunset the moist air mass east of the dryline was consistently denser than the dry air mass. This air density difference waned and even reversed after sunset, because of more rapid cooling on the dry side.

This study provides further evidence that the formation and propagation of the dryline convergence zone is driven by the daytime air density difference, that is, that the dryline behaves as a density current. The implication for forecasters is that the air density (or virtual potential temperature) difference across the dryline should be monitored, as a measure of dryline strength and as an additional indicator for the likelihood of convective initiation along the dryline.

Corresponding author address: Bart Geerts, Dept. of Atmospheric Sciences, University of Wyoming, Laramie, WY 82071. Email: geerts@uwyo.edu

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