November 18, 2016 Meeting

The third meeting of the 2016-2017 year took place at the National Weather Service Jackson office.

Meeting Minutes

Call to Order
The third meeting of the 2016-2017 AMS/NWA chapter was called to order at 12:18pm by NWA President Eric Carpenter. The meeting was held at the National Weather Service office in Flowood.

Recording Secretary Joanne Culin passed around a sign in sheet. Nineteen people were present.

Minutes Approval
Minutes from the October meeting were summarized by Recording Secretary Joanne Culin.

New Business
The business session began with a treasury report. Treasurer David Cox gave the report. At the beginning of the meeting, $230.50 was in the treasury. One regular member and one student member paid dues, and a new regular member paid dues. A total of $33 was spent on pizza for the meeting, bringing the budget to $247.50. As a reminder, memberships are now valid for an entire year, rather than just through the remainder of the current chapter year.

NWA President Eric Carpenter proposed that the chapter continue our holiday season tradition of donating socks to Grace Place at Galloway United Methodist Church in Jackson, where the socks will be distributed to the local homeless population. Socks will be collected at NWS Jackson through the winter months. Members can also bring their sock donations to the December meeting, which will be advertised very soon.

NWA Vice-President Will Day discussed a national NWA webinar he watched titled “Advanced Social Media Strategy”. The webinar discussed innovative ways to collect and distribute weather information via Twitter. Will took notes, and he plans to share them with the rest of the chapter soon.

Due to scheduling issues, our original guest speaker was unable to attend the meeting. Fortunately, Eric Carpenter was willing to step in at the last minute and share a presentation he is working on that discusses past research he was involved with on tropical cyclone rainfall patterns as they relate to the August 2016 Lower Mississippi Valley flood. The original study was titled “Composite Analogs for Tropical Cyclone Rainfall Patterns Over the Lower Mississippi Valley”. Along with Eric, this study was authored by chapter Treasurer David Cox, Chad Gravelle of St. Louis University, and Russel Chauvin of Mississippi State University.

The goal of the study was to find useful rainfall patterns in tropical cyclones using historical weather data, so that forecasters can better anticipate heavy rainfall potential with future
tropical systems based on the antecedent atmospheric pattern. Among the systems in the dataset used in the study were tropical cyclones that passed within a radius centered over Bude, Mississippi. These systems were split into two regime categories – those which occurred within upper ridging and those which were influenced by upper troughing. The trough influenced systems tended to be more progressive, with generally lesser rainfall amounts that tended to be focused farther east in the region. On the other hand, systems that occurred within an upper ridge pattern tended to have slower and more erratic motion due to weaker steering flow. These systems tended to result in higher rainfall totals, especially closer to the coast and over the southern and western half of the region, with a strong gradient in rainfall amounts to lesser totals over the northern and eastern portion of the region.

After reviewing the results of the study, Eric provided a case study of the system which produced prolific flooding across portions of Louisiana and Mississippi in August of this year. This system, though never officially classified as tropical, exhibited characteristics very similar to the ridge influenced tropical cyclone type covered in the aforementioned study. As the analog systems did in the study, this system produced significant rainfall amounts, with the greatest totals nearer to the coast and a sharp gradient in amounts on the northern side of the system. Finally, Eric quickly reviewed WPC and WFO Jackson forecasts for the system.

The meeting concluded at 1:30 pm, and it was adjourned.

Minutes were submitted by Daniel Lamb, Corresponding Secretary.

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