The 2019 Atlantic hurricane season ended on November 30 but not before churning out 18 named storms, including catastrophic Hurricane Dorian. Throughout the season, AOML’s hurricane scientists were at the forefront of NOAA’s efforts to prepare vulnerable communities for severe weather.
AOML’s hurricane scientists conducted multiple airborne missions into several tropical systems that formed in the Atlantic in September and October. The data gathered in Humberto, Jerry, pre-Karen, Lorenzo, and Nestor improved track and intensity forecasts, aiding NOAA’s efforts to prepare vulnerable communities for severe weather. The missions also supported research to better understand how tropical cyclones form, intensify, and dissipate, as well as supported efforts to validate satellite measurements of these storms.
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.
AOML is currently in the midst of a multi-year effort called the Intensity Forecasting Experiment (IFEX). IFEX aims to improve the understanding and prediction of intensity change by collecting observations from all stages of a tropical cyclone life cycle—genesis to decay—to enhance current observational models. By building on years of observational expertise and cutting-edge approaches to data integration and model development, hurricane scientists at AOML lead advancements in observations and modeling that have improved intensity forecasts by 20% in recent years.
NOAA Hurricane Hunters are flying back-to-back missions to study the newly developed Tropical Storm Hermine in the Gulf of Mexico, capturing its evolution from a cluster of thunderstorms into a tropical storm. Getting data during such transitions can help improve hurricane models which currently don’t predict transitions well. Our understanding of the physical processes of early storm development remains limited, largely because there are few observations.
As a hurricane approaches landfall, citizens are hoping that they are adequately prepared for the potential damage from strong winds and rising oceans. NOAA’s job is to forecast the storm location and strength, or intensity, to help communities make the best informed decisions. For many scientists, predicting intensity is a challenge at the forefront of hurricane research, and in recent years advancements in observations and modeling have improved NOAA’s forecasts of intensity by 20%. We are now at the point where scientists can observe and predict with very fine detail what is happening in the inner core of the storm.
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.
Hurricane Danny & Tropical Storm Erika Provide Wealth of Research Opportunities for the 2015 Hurricane Field Program
AOML’s hurricane researchers conducted a number of field activities in August that provided data and critical insights into two Atlantic tropical cyclones, Danny and Erika. The two storms enabled researchers to test new instruments in support of the 2015 Hurricane Field Program and conduct research that will benefit future forecasts. Among the highlights were more than 15 successful manned and unmanned aircraft missions into Danny and Erika to collect and provide real-time data to the National Hurricane Center (NHC), as well as evaluate forecast models.
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.