Sunday, 22 January 2012
A Study on Convective Modes Associated with Tornadoes in Central New York and Northeast Pennsylvania
Hall E (New Orleans Convention Center )
Between August 2000 and May 2011, the National Weather Service (NWS) Binghamton's county warning area (CWA) experienced 52 tornadoes. This study examines various characteristics of these events, with a focus on how these characteristics vary by convective storm mode. The study began by identifying the most common convective storm modes associated with tornadoes within the CWA. During the study period, supercells produced the majority of tornadoes and Quasi-Linear Convective Systems (QLCS) produced the second largest number of tornadoes. To better understand the synoptic conditions that produced these different convective modes, composite maps were generated for upper levels of the atmosphere by NOAA's Earth Science Research Laboratory website. Composite maps revealed that QLCS synoptic scale patterns were characterized by more highly amplified troughs to the west of the CWA. However, composite synoptic patterns for Supercells were characterized by weaker upper level troughs. After gaining an understanding of the synoptic scale patterns associated with different convective modes, the study sought to gain a better understanding of the associated mesoscale environments. By utilizing archived Storm Prediction Center RUC analyses, the study identified mesoscale parameters for each tornado. These parameters were grouped by convective mode to develop statistics on the mesoscale environments associated with each mode. Supercells were associated with moderate instability and shear, while QLCSs occurred in environments with low instability and high shear. Null events were also analyzed to identify mesoscale environments where tornadoes may be less likely to form. Results showed that supercells in environments with weak 0-1 km bulk shear, as well as weak 0-1km and 0-3km storm-relative helicity, were more likely to produce null events. These environmental characteristics were combined with an associated radar study to create nomograms for various radar products. The combined results of all three portions of the study are intended to aid NWS Binghamton forecasters in forecasting tornadoes and issuing severe weather warnings.