A major component of NOAA’s Hurricane Forecast Improvement Program (HFIP) is the Stream-2 activity. The purpose of this activity is to demonstrate that the application of advanced science, technology, and increased computing will lead to the desired increase in accuracy, and other improvements of hurricane forecast performance. The jet high-performance computing facility located at Boulder is used for this effort. It should be mentioned that all major R2O transitions of HWRF resulted from HFIP-Stream-2 activity. For this hurricane season, both an advanced version of the HWRF system, called the basin-scale HWRF, that is being developed at the NOAA’s Hurricane Research Division of the Atlantic Oceanographic and Meteorological Laboratory and the FV3-Global Forecast System that is being advanced at NOAA’s Geophysical Fluid Dynamics Laboratory for operations were run real-time in parallel with the operational global (GFS) and regional (HWRF) systems for the 2017 hurricane season in the HFIP jet high performance computer. Both HFIP experimental models showed significant track improvements over the parent models (GFS and HWRF). For instance the basin-scale HWRF was at least 10% better in terms of tracks when compared to HWRF as well as GFS for all major land-falling hurricanes in 2017 (Harvey, Irma and Maria). In this talk we will especially focus on the intensity and structure predictions from the 2-km runs of the basin-scale HWRF system for these land-falling hurricanes.
For the first time, tail doppler radar observations from NOAA P3s and High-Density observations (HDOBS from P-3, C-130) were assimilated into the basin-scale HWRF for Harvey, Irma and Maria. This experimental HWRF configuration was the best NOAA model for Hurricane Harvey. The model captured accurately the rapid intensification (RI) event before landfall, and the slow and nearly stagnant motion of Harvey that resulted in record rainfall in and around Houston, Texas. In the case of Irma, the basin-scale HWRF forecasted the tracks, intensity changes associated with the terrain interactions over Espaniola, the large rainbands and the associated helicity over Florida near and at landfall very well. In the case of Maria, the basin-scale HWRF, again, captured the RI several cycles in advance. At the meeting apart from conventional verification, we will provide some details of the inner core structure and comparisons with aircraft observations for all the 3 cases. We will also discuss the challenges associated with structure and intensity predictions especially in context of Harvey and provide recommendations for further improving tropical cyclone guidance.