The first monthly conference call for the CSTAR Tropical Cyclone Wind group was held on March 14, 2012 at 11 AM. Participants on the call were Bryce Tyner (NCSU), Dr. Anantha Aiyyer (NCSU), Jonathan Blaes (RAH), Frank Alsheimer (CHS), Bob Bright (CHS), Larry Brown (AKQ), John Billet (AKQ), and Reid Hawkins (ILM).
Bryce gave a presentation on his current work. The topics included the decay of winds of typical landfalling tropical cyclones and update on modeling work. The set of cyclones in his database were Kyle ’02, Isabel ’03, TD7 ’03, Charley ’04, Gaston ’04, Ernesto ’06, Gabriella ’07, Hanna ’08, and Irene ’11. He discussed the datasets he used, and noted ASOS typically go missing when impacted by the storms. Also, he stated HWND analysis by HRD is not often available when storms are overland. Frank mentioned that primary inputs into the HWND are from data collected by the hurricane hunters and NOAA research aircraft, and they do not fly into the storm when they area over land. Therefore to have a reliable analysis Bryce has chosen the RUC analysis for comparison to the NDFD winds. He requested advise/comments on other datasets that were available, NARR and CFSR. He wanted to know if the group had any comments on which dataset was best.
Bryce’s preliminary findings were that for stronger tropical storms there was a great period of decay between 6 and 24 hours. For weaker storms the decay was not found.
It was also discussed to look at decay based on the four quadrants of the storm. Bryce said he would look into it and present results at the next monthly conference call.
Bryce then discussed his latest test run of WRF for Irene (2012). Prior runs led to a storm that made landfall several hours prior to what is indicated in best track data, likely due to the strength of an impinging upper level trough from the west. In order to get a more realistic simulation, Bryce initalized the storm 12 hours prior to landfall, rather than 48 hours prior to landfall. An analysis of SLP, near-surface winds, and precipitation distributions suggested this was enough time prior to landfall to spin-up a realistic storm structure. The storm made landfall within an hour of what is indicated in the best track data, and the track is very accurate for several days after landfall. Since the simulation appears rather close to the analysis fields, future work will involve initial WRF-LES simulations, following the work in Zhu et al (2008) for Ivan (2004).
Finally, the group discussed the presentation that Byrce will give for the CHS Tropical Webinar at the end of April. Also, preliminary outline of training slides was prepared by Gail Hartfield. The group discussed the list with few minor changes to the topics. The slides will show where we (WFOs) have been when preparing wind and wind gust grids, what has been learned with climatology studies and verification from past storms, and what the CSTAR project hopes to provide in the future. Bob and Gail discussed having a 1st draft by middle of April. This training is expected be incorporated into Bob’s and Franks yearly Tropical training that is distributed to the regions.
Slides from the call can be viewed here:
Conference Call 3/15 Slides
The Next call will be 11 AM on April 11th.