67 Mesoscale Convective System Maintenance across Lake Michigan: A Research to Operations Example

Thursday, 8 August 2013
Holladay-Halsey (DoubleTree by Hilton Portland)
Justin Arnott, NOAA/NWS, Gaylord, MI; and F. Fredrickson and N. D. Metz

Forecasting the maintenance of Lake Michigan-crossing mesoscale convective systems (MCSs) is an important concern for operational forecasters over lower Michigan. Recent research has implicated numerous synoptic and mesoscale features as conducive to MCSs surviving a west to east trip across Lake Michigan. Some of these features include: ample downstream instability across lower Michigan, a robust low-level jet impinging on the MCS, the presence of an elevated mixed layer, and a right-entrance region of an upper-level jet streak over lower Michigan.

This presentation will assess the applicability of this recent research to an operational forecasting setting. The National Weather Service office in Gaylord, Michigan developed a checklist incorporating seven different parameters that differentiate between MCS persistence and dissipation, with the goal of giving forecasters a useful tool to anticipate the arrival of severe weather. This checklist was evaluated for 68 cases during the 2005-2011 warm seasons. During this period, 42% of cases that featured convection upstream over Wisconsin were successfully able to move into lower Michigan and also produce at least one severe weather report. The results indicate that the checklist has utility in discriminating between cases that survive lake crossing and those that do not. This utility is increased when looking at cases that produced more widespread (≥10 reports) severe weather. From this initial assessment, the checklist was modified slightly and will be used operationally during the 2013 warm season. Preliminary results from this real-time operational use will also be discussed.

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