An evaluation of using lightning data to improve aviation oceanic convective forecasting for the Gulf of Mexico

The National Weather Service (NWS) Aviation Weather Center (AWC) developed a product that overlays "long-range" lightning data onto Infra-Red (IR) satellite imagery. These lightning data are an extension of the National Lightning Detection Network (NLDN) developed and operated by Global Atmospherics, Inc. (GAI), and the Canadian Lightning Detection Network (CLDN) owned by Environment Canada. The Federal Aviation Administration (FAA) and the NWS promoted an evaluation of this product under the National Lightning Contract between the NWS and GAI, with participation from government (NWS, FAA, and Department of Defense (DoD)) as well as non-Government users (airline meteorologists and dispatchers) from April 1999 to January 2000.

Given that satellite imagery alone cannot always detect the presence of convection activity underneath the clouds, the primary purpose of the evaluation was to determine if merging it with 'long-range' lightning data would aid aviation forecasters/dispatchers in identifying regions of oceanic convection. The results of the evaluation indicated that CWSU meteorologists and other Air Route Traffic Control Center (ARTCC) personnel, as well as airline dispatchers, found this product beneficial in monitoring convective storm development over the Gulf of Mexico (GOM) and the Caribbean. AWC meteorologists have used this lightning product for some time now and found it quite useful in issuing International Significant Meteorological Information (SIGMETs) for convection, and in routing aircraft away from hazardous thunderstorms over oceanic regions.

The evaluation indicated that there was a large difference in long-range NLDN/CLDN thunderstorm detection efficiency between day and night due to diurnal influences on the ionosphere. For convective forecasting, thunderstorm detection is most important/critical for flight planning and route deviation. This 'long-range' lightning product had an excellent thunderstorm detection efficiency of close to 100% within 1000 km of CONUS (day/night), with only a slight decrease to 70-80% within 3500 km (night) and 2000 km (day) of CONUS.

The FAA is endorsing a multifaceted program centered on the requirement to improve air traffic control services in the offshore airspace of the Houston ARTCC and the U. S. controlled Oceanic Flight Information Region (FIR) in the GOM region. Initial requirements regarding weather will address shortfalls in oceanic convective observations and forecasting. Air traffic in the GOM region will increase significantly in the next decade. To efficiently deal with the increase in capacity, it is likely that the horizontal separation normally used between aircraft flying over oceanic regions will be reduced. Accommodating this increase in GOM growth and capacity would dictate improvements in the availability of current and forecast weather data as well.

The Oceanic Convective product has the potential to play a significant role in supporting increased airspace capacity in the GOM region without degrading safety. Furthermore, it could reduce the incidences of non-coordinated deviations due to weather through greater situational awareness. This product will advance collaborative decision making processes, especially over oceanic regions where surveillance and communications are not optimal. An assessment of this Oceanic Lightning product over the GOM should clearly establish if the value of this product is sufficient to 1) develop a need for routine access to this product for the GOM region, and 2) expand the network to enhance data availability over the Caribbean, Central America, and South America with improved detection and location accuracy.