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Investigation of Lightning Patterns Over New Jersey and Surrounding Area Al Cope National Weather Service Mount Holly, NJ Adam Gonsiewski Millersville University

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Introduction Research on lightning patterns in New Jersey and surrounding areas, with a focus on the summertime months of June, July, and August, was conducted during the summer of 2010 at the National Weather Service Forecast Office in Mount Holly, New Jersey. The goal was to see whether or not lightning had different tendencies across the region based on month, hour of the day, 500 mb flow direction, synoptic regime, and day classification (event, contaminate, or null). This work was designed to coincide with a related study on summertime convective initiation over New Jersey, being conducted by NWS Mount Holly and Kean University.

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Procedure 1.Obtain CG-Lightning from Vaisala for 2004-08. Extract a subset of lightning data over the study area. 2.Use spreadsheet program to sort the data by month, hour of the day, upper-air flow, synoptic regime, and day classification (event, contaminate, and null). 3.Create tables and graphs showing lightning distribution by day and time. 4.Write a FORTRAN program to put the data into a 21km x 22km grid array (sort lightning by location). 5.Upload the array output from the FORTRAN program onto www.GPSvisualizer.com in order to produce flash frequency maps.

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The map to the left shows the total summertime lightning strikes from 2004- 2008 across the region. The overall lightning distribution shows a maximum over the Chesapeake Bay region extending north across eastern PA. There is a minimum in strikes off the coast of New Jersey (due to colder waters?)

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Daytime T-Storm Trends: SW vs. NW Flow Aloft

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Daytime T-Storm Trends: Cold Front vs. High Pressure

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Conclusions Lightning activity peaks in late afternoon (diurnally) and in mid-summer (annually) For any given month, large inter-annual variation is possible Diurnal maximum becomes earlier from spring into summer Half of all summer lightning occurs with SW flow aloft; half is associated with cold fronts Diurnal trends vary somewhat with flow aloft and surface synoptic pattern

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Future Work Obtain and analyze lightning data from additional years Examine diurnal trends past 00Z Create contoured analyses of flash density

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Acknowledgements Lightning data provided by Vaisala (gratis) THE END