Authors: Heidi Van Buskirk
Date: June 17, 2019
Hurricane season is officially upon us and researchers at NOAA’s Atlantic Oceanographic and Meteorological Laboratory are excited about new model developments and innovative technology to improve hurricane forecasting. AOML’s deputy director, Molly Baringer, briefed Congresswomen Debbie Wasserman Schultz and Donna Shalala on May 30th, 2019 about the science behind the 2019 Atlantic Hurricane Season Outlook and advancements led by AOML and other NOAA offices in the field of hurricane forecasting. Highlights of the briefing are below:
NOAA Predicts a Near-Normal Season
Hurricane season began on June 1st and ends on November 30th, with the peak of the season occurring between mid-August to late-October. Due to competing climate factors at play this year, NOAA researchers predict a slightly higher (40%) chance of a normal season with a range of 9 to 15 named storms (winds of 39 mph or higher), of which 4 to 8 have the potential to become hurricanes (winds of 74 mph or higher), including 2 to 4 major hurricanes (category 3 or higher with winds averaging above 111 mph). The ongoing El Nino is expected to persist and produce strong vertical wind shear across the Caribbean which has the potential to suppress hurricane activity. To the east, above average sea surface temperatures in the Atlantic will create conditions which are likely to generate increased hurricane activity. The outlook should be viewed as a general guideline and never relied upon as a landfall forecast. Hurricane preparation is critically important as it only takes one storm to devastate a community.
Improved Hurricane Models
Each year NOAA hurricane researchers strive to deliver more accurate hurricane guidance from improved models and new observations of storm structure from hurricane hunter aircraft as tropical storms take form. The Hurricane Weather Research and Forecast (HWRF) model has demonstrated remarkable improvements as a result of the Hurricane Forecast Improvement Program, which aims to reduce the average errors of hurricane track and intensity forecasts. Thanks to increased model resolution and assimilation of observations from aircraft flying in the hurricane’s inner core, the HWRF model has shown a 50% improvement in hurricane intensity forecast accuracy for 3-day forecasts since 2009.
NOAA is also testing a new basin-scale version of this model which allows multiple storms to be forecast simultaneously, more accurately capturing storm interactions. In 2018, this model was recognized as the best research model and was the only hurricane model to accurately predict the weakening of Hurricane Isaac while Hurricane Florence moved toward a U. S. landfall and Hurricane Helene turned to the North Atlantic.
In the future, the best of these models will be extended to the Hurricane Analysis and Forecast Systems (HAFS) which will incorporate the abilities of the basin-scale model to track multiple moving storms with NOAA’s flagship global weather model, the Global Forecast System (GFSFV3). HAFS will build upon the first major upgrade to the global forecast system in nearly 40 years, the addition of a new dynamic core, and will enhance tropical cyclone track and intensity forecasts.
Improved Hurricane and Ocean Observations
AOML scientists are using new technology to expand data collection both in air and at sea, with a goal of better representing storm and ocean conditions in the models. Tail Doppler radar systems onboard NOAA’s P3 Hurricane Hunter aircraft will collect higher resolution data on wind field structure from within tropical storms. This data will be sent in near real-time to specialists at the National Hurricane Center as well as forecasters at NWS local weather forecast offices. NOAA’s advanced GOES-16 satellite will provide high resolution imagery on storm location and structure to allow for better situational awareness.
In addition to data collected in the air, NOAA will expand ocean glider deployments in the Caribbean and tropical Atlantic. NOAA is increasing glider coverage and will deploy up to 20 gliders this season, with Navy partners deploying an additional 18 gliders. These ocean gliders will sample and report ocean characteristics beneath approaching tropical systems, such as temperature and salinity which are indicative of the heat energy available to fuel passing storms. The valuable data collected from ocean gliders will improve ocean conditions in coupled hurricane model guidance, with an expected result of improved intensity forecasts.
Creating a weather ready nation is NOAA’s top priority. Improved observations, data assimilation, and development of reliable models will allow our scientists to evaluate storms as they form and interact with various atmospheric and oceanic conditions. In doing so they can make sure vital up-to-date information on hurricane location and intensity reaches the public such that necessary life and property saving precautions can be taken.