Several studies have taken place (see Lambert et al., 2005) whose results have direct relevance to this work. The climatological lightning probabilities in this work are defined by the flow regimes over the Florida peninsula as described in Lericos et al. (2002) and Lambert and Wheeler (2005). This effort is a follow-on to the development of flow regime-based climatologies and a first-guess lightning threat index map (Lambert et al., 2007), and flow regime-based climatological vertical profiles of temperature, dew point, and wind for the morning soundings in Florida at Miami, Tampa, Jacksonville and Cape Canaveral Air Force Station.
• Ridge north of Florida,
• Ridge south of Florida
• Ridge between TBW and JAX
• Ridge between TBW and MFL
• Ridge over Panhandle
• Peninsular NW flow
• Peninsular NE flow
• Undefined Regime
The AMU used a grid of NLDN data approximately 1012 km x 943 km that covered the area from 24 °N/88 °W, 24 °N/78 °W, 33 °N/88 °W, 33 °N/78 °W. The NLDN grid was sub-divided into 152,685 2.5 km x 2.5 km squares that contained the number of CG strikes per square. The latitude and longitude of the center of the runways at the airports and SLF were determined to establish the number of 2.5 km x 2.5 km squares approximately corresponding to 5-, 10-, 20- and 30-n mi circles for each location. Pre-existing code from the previous work was modified to sum the number of CG strikes in each square over the POR and to then calculate the probability of lightning occurring within the area approximately defined by the four circles around the runways at each location for 1-, 3- and 6-hour increments beginning at 00 UTC each day.
The AMU developed an HTML-based graphical user interface (GUI) tool to allow the forecasters quick and easy access to the results of this work in an operational setting. The GUI runs within most popular web browsers and permits the forecasters to view the results for each location in tabular and graphical format.
The flow regime-based lightning distributions from gridded cloud-to-ground (CG) lightning data from the National Lightning Detection Network (NLDN) (Cummins et al. 1998) were used to compute the probability of lightning at the SLF and the airports in the NWS MLB area of responsibility. The period of record (POR) for the data was the warm seasons (May-September) in the years 1989-2004. The eight flow regimes were defined as follows: