Catastrophic Hurricane Dorian will be long remembered as one of the Atlantic basin’s most powerful landfalling hurricanes. NOAA Hurricane Hunters measured Dorian’s intensification from a weak tropical storm in the Caribbean to one of the Atlantic’s fiercest hurricanes. The data they gathered were vital to protecting life and property, supporting NOAA’s efforts to warn vulnerable communities of approaching severe weather through accurate forecasts.
AOML drives improvements to hurricane forecasts by leveraging expertise in tropical cyclone observations, research, and modeling. Our numerical weather modeling team uses HWRF to test new technology and advance hurricane prediction through data collection, assimilation, and experimental modeling.
Over the past 20 years, improvements in hurricane computer modeling, observational instrumentation, and forecaster training have greatly increased forecast accuracy. The many complex interactions that occur within the atmosphere remain to be fully understood, especially at the small scales associated with tropical cyclones. However, these milestones mark critical advances in numerical weather prediction that are paving the way to the next generation of NOAA models. While hurricanes cannot be controlled, vulnerability to these complex storms can be reduced through preparedness. Early warning and improved accuracy of forecasts can help save lives and reduce property damages caused by hurricanes.
Early on the morning of August 29th, 2005, Hurricane Katrina made landfall on the Louisiana delta region and the Mississippi coast. The storm surge brought enormous damage to the Gulf Coast and, when the levees around New Orleans failed, a great number of fatalities. Coming amidst the very busy 2005 hurricane season, Katrina brought death and destruction not seen in a U.S. land-falling hurricane in decades.
With the 2015 Atlantic hurricane season underway, researchers are pointing to the strong presence of El Niño as the major driver suppressing the development of tropical cyclones in the Atlantic basin. But what specific conditions are associated with El Niño that lead to a less than ideal environment for tropical cyclone development? Through research and observation, hurricane researchers know strong environmental wind shear is a major factor affecting potential hurricane development and growth. This hurricane season, AOML researchers are delving further into the relationship between wind shear and tropical cyclones.
This hurricane season, NOAA’s Office of Oceanic and Atmospheric Research will work with NOAA’s National Weather Service to upgrade weather forecast models and conduct research with unmanned air and water craft to improve forecasts of hurricane track and intensity.A highlight this season is the upgrade of the operational Hurricane Weather Research and Forecast system (HWRF), an advanced hurricane prediction model. This year’s version now has increased the resolution from 3 to 2 kilometers, and will use tail Doppler radar data collected from the NOAA P-3 and G-IV hurricane hunter aircraft to improve the storm representation within the model.
The Atlantic hurricane season will officially end November 30, and will be remembered as a relatively quiet season as was predicted. Still, the season afforded NOAA scientists with opportunities to produce new forecast products, showcase successful modeling advancements, and conduct research to benefit future forecasts.
The 2013 Atlantic hurricane season, which officially ended on November 30th, will be noted in the record books as having been a relatively quiet year with the fewest hurricanes since 1982. In fact, it will be ranked as the sixth least-active Atlantic hurricane season since 1950.
Despite this, the 2013 season was quite an active year for scientists with AOML’s Hurricane Research Division (HRD). Flying aboard NOAA’s hurricane hunter aircraft, they conducted missions into Tropical Storms Gabrielle and Karen, as well as Hurricane Ingrid, to gather data for research and assimilation into numerical models.
These data were collected as part of HRD’s annual Hurricane Field Program, a large component of which is the Intensity Forecasting Experiment (IFEX). A goal of IFEX is to better understand the physical processes and other factors that enable tropical cyclones to change intensity, as well as improve tropical cyclone intensity forecasts.
As part of their efforts to gather data for research, HRD scientists released 136 airborne expendable bathythermographs and 367 dropwindsondes from NOAA’s P3 and Gulfstream-IV (GIV) aircraft. These instruments enabled them to obtain information about important features in the atmosphere and ocean. The G-IV jet gathered data during nine flights and the two P3 aircraft conducted 17 missions, for a total of 150 flight hours spent sampling these three tropical systems. Many of the flights were coordinated with NASA’s Hurricane Severe Storm Sentinel missions, which featured two high-altitude, unmanned, Global Hawk aircraft.
One of the highlights of the season was that, for the first time, the P3’s tail Doppler radar data were transmitted directly to NOAA Central Operations and successfully assimilated into the operational HWRF model. This was a significant accomplishment for NOAA that enabled the P3’s Doppler radar data to be included in the latest high-resolution models as part of the effort to continually improve intensity and track forecasts. The tail Doppler radar data provided vital information about the direction and strength of the winds found in Gabrielle, Ingrid, and Karen.
On the modeling and data assimilation fronts, a new basin-wide version of the Hurricane Weather and Research Forecast (HWRF) model developed at HRD was run in real-time during the season, allowing for multiple storms to be forecast concurrently for the first time. Additionally, HRD provided near-real-time runs of a research version of HWRF initialized with the Hurricane Ensemble Data Assimilation System (HEDAS), a testbed for improving the assimilation of data into the operational HWRF model.
For the first time, high-resolution cloud-motion vectors, as well as other satellite retrievals, were ingested with HEDAS. The model forecasts showed that the assimilation of these data with a sophisticated data assimilation system could provide better forecasts of track and intensity than the current operational system. HRD’s HWind group successfully made 33 surface-wind analyses for six storms that formed in the Atlantic basin this year.
HRD scientists are thankful for the successes and major milestones achieved during the 2013 Atlantic season, all without having a single hurricane make landfall in the U.S. and with only minimal loss of life and property to the public due to tropical systems.