HR: 1340h
AN: A53A-0912    [Abstracts]
TI: Investigation of Convective Initiation Along a Dryline Using Observations and Numerical Weather Prediction Model
AU: * Weldegaber, M H
EM: mengs1@umbc.edu
AF: University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, United States
AU: Demoz, B B
EM: Belay.B.Demoz@nasa.gov
AF: NASA-Goddard Space Flight Center, Code 613.1, Greenbelt, MD 20771, United States
AU: Sparling, L
EM: sparling@umbc.edu
AF: University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, United States
AU: Hoff, R M
EM: hoff@umbc.edu
AF: University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, United States
AU: Chiao, S
EM: schiao@fit.edu
AF: Marine and Environmental Systems Florida Institute of Technology, 150 W University Blvd, Melbourne, FL 32901, United States
AB: A narrow zone of strong horizontal moisture gradient, known as a dryline, is frequently observed over portions of the Southern Great Plains of the United States. The dryline is a boundary separating warm, moist maritime air from the Gulf of Mexico and hot, dry continental air from southwest U.S. and northern Mexico. The dryline acts as a focus for severe convective storms, and often leads to flooding and tornadoes. Although most storms initiate at or near the dryline, the exact processes by which convection is triggered and the preferred location for convection along the dryline are not well understood. Because the underlying processes are highly nonlinear, current numerical weather prediction (NWP) models show poor skill in their ability to accurately forecast these events. In this research a non-convective dryline case over Oklahoma and Texas panhandle on 22 May 2002 was considered. Using extensive high spatial and temporal resolution observational data from the International H2O Project, a field campaign in 2002 (IHOP_2002), and the National Center for Atmospheric Research (NCAR) Weather Forecasting and Research (WRF) model moisture evolution and variability in the boundary layer is thoroughly analyzed and investigated. Performance of the model and the possible reason why the anticipated dryline on 22 May 2002 did not trigger convective storm over Homestead - OK area are discussed. Results of the observational analysis indicate that abundant moisture did not sustain over Homestead - OK area during 22 May 2002. Moreover, vertical structure of water vapor mixing ratio indicate that moisture was not deep enough for vertically moving air parcels due to the dryline convergence provide the necessary destabilization effect to support deep convection initiation during this period.
DE: 0545 Modeling (4255)
DE: 0550 Model verification and validation
DE: 3307 Boundary layer processes
DE: 3314 Convective processes
DE: 3329 Mesoscale meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting