P2.1
Estimating boundary-relative flow in forecasting convection
James G. LaDue, WSR-88D, NOAA/NWS/OSF, Norman, OK; and A. Wood
Recent evidence has suggested that low convective cell bearing flow orthogonal to the orientation of a surface boundary (low Ub ) is a favorable condition to initiate and maintain deep convection under relatively benign large scale forcing. Recent techniques have been developed to help forecasters estimate Ub upon knowing a boundary motion and mean flow vectors. However, the time needed for calculating Ub has made its application to short-term convective forecasting problematic. In this study, a technique has been generalized to a web-based tool to help expedite the process of estimating Ub for boundaries moving in any direction and speed.
This paper uses a method a forecaster can use to estimate Ub for any boundary and access to the boundary-relative flow web applet. This method can be used as a consideration in assessing the potential of a boundary to initiate and maintain convection under relatively weak large scale forcing. In addition, this technique for estimating Ub may help to anticipate how a boundary influences the mode of organized convection in stronger large scale forcing. Additional applications of this technique can be used to estimate the orthogonal component of shear to a boundary. Several examples show the application of this technique in both weak and strong synoptic forcing with the help of the Advanced Interactive Weather Processing System (AWIPS). The boundary-relative flow applet can be found at http://www.osf.noaa.gov/otb/working/boundary.
Poster Session 2, Convective Initiation
Tuesday, 12 September 2000, 4:30 PM-6:30 PM
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