Dropsonde and Airborne Radar Observational Strategies for Improved Operational Tropical Cyclone Prediction (Invited Presentation)

Two recent Tropical Cyclone (TC) Forecast Demonstration Projects have utilized new and innovative technologies and targeted observing strategies for improving TC track and intensity forecasting: 1) Sensing Hazards with Operational Unmanned Technologies (SHOUT, 2015-16) and 2) East Pacific Origins and Characteristics of Hurricanes (EPOCH, 2017). Both of these projects share the objective of complementing legacy G-IVSP RD-94 dropsonde observational capability of the mid- and upper troposphere with improved NRD-94 mini-dropsondes deployed from Global Hawk UAV vehicles in the lower stratosphere. Recently G-IV Tail Doppler Radar (TDR) observations have become available to complement WP-3D TDR observations. Combined use of TDR observations and Global Hawk dropsonde observations are examined in this paper.

A new dropsonde targeting strategy was developed at UASUNY using ECMWF ensemble forecasts in the 48-72 hour period to estimate regions of high observational uncertainty for prediction of track and intensity. The Global Hawk patterns flown in both of these projects used this strategy in developing dropsonde deployment locations for each flight. This paper describes how the resulting dropsonde locations compared with these regions of maximum uncertainty. In addition, the locations of these high uncertainty regions relative to key environmental and storm relative features is described and depicted using GOES visible and IR imagery, microwave imagery and concurrent airborne and land-based radar imagery.

Sample operational model runs will be presented on the relationship between operational HWRF track and intensity prediction with and without the high-altitude dropsonde observations and with and without G-IV TDR observations. In addition, introduction of new RD-41 dropsonde technology for the 2018 hurricane season will be summarized.