Extended Abstract (752K)12A.1
Predictability of Convective Storm Initiation
James W. Wilson, NCAR, Boulder, CO; and R. Roberts
The data rich 2002 IHOP is used to study the predictability of convective storm initiation. The location and time of all storm (>40 dBZ) initiation occurring over the IHOP domain for the entire project is documented along with the suspected triggering mechanism. This information is used to evaluate how well the RUC and LAPS/MM5 numerical models nowcast precipitation initiation. The focus will be on the 0-6 hr nowcast period. Mosaics at 10 min intervals of 10 NEXRAD’s and the NCAR S-pol are used to identify storm initiation and boundary layer convergence lines (boundaries). A plethora of surface stations and GOES 8 and 11 visual cloud observations are used along with the radar data to identify and characterize boundaries.
In order to help assess model strengths and weaknesses the nowcast fields of precipitation, vertical motion, surface convergence and stability will be compared with the observed storms and boundaries. The predictability of storm initiation is closely tied to the scale of the triggering mechanism or to the synoptic situation. Particularly difficult is the prediction of elevated convection that generally initiates during the night. For these cases there is often no obvious synoptic triggering mechanism and there is little means to observe sub-synoptic scale triggering mechanisms as is the case with radar and satellite with surface based convection.
Based on the above analysis inferences will be made about how well the models are capturing boundaries their characteristics and stability variations that modulate precipitation initiation and evolution.
Session 12A, IHOP/Boundary Layer
Monday, 11 August 2003, 4:00 PM-6:00 PM
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