An Objective Aid for DoD Base Preparations in Advance of Tropical Cyclones

The Department of Defense uses the Tropical Cyclone Conditions of Readiness (TC-COR) system to prepare bases and evacuate assets and personnel in advance of adverse weather associated with tropical cyclones (TCs). The TC-CORs, also known as CORs or HURCONs, are recommended by weather facilities either on base or from central sites. TC-COR recommendations are then considered by base or area commanders along with other factors (e.g., presence of vulnerable assets) for setting the TC-CORs. TC-CORs are defined in terms of the potential of destructive (i.e., 50 knot) winds. Ideally, TC-CORs are set sequentially, from TC-COR IV (destructive winds possible within 72 hours) through TC-COR III (destructive winds possible within 48 hours) and TC-COR II (destructive winds anticipated within 24 hours), and finally to TC-COR I (destructive winds anticipated within 12 hours), if needed. Each TC-COR, once set, initiates a series of preparations. Preparations for TC-COR IV can be as unobtrusive as obtaining emergency supplies, water and portable radio while preparations for TC-COR I are generally far more costly, intrusive and labor intensive. In this work we describe an objective decision aid that provides TC-COR recommendations based on wind probability thresholds from an operational wind probability produced by U. S. tropical cyclone forecast centers. An analysis on 113 independent cases from various bases shows the skill of the objective aid and how well it compares with the operationally-issued TC-CORs. Sensitivity analysis is also done to demonstrate some of the advantages and pitfalls of increasing or lowering the wind probability thresholds used to determine TC-COR guidance.

Disclaimer: The views, opinions, and findings contained in this manuscript are those of the authors and should not be construed as an official National Oceanic and Atmospheric Administration or U.S. government position, policy, or decision.