FA2521-18-Q-B091_Nocturnal_Lightning_PWS.pdf

PERFORMANCE WORK STATEMENT

FOR

UNEXPLAINED NOCTURNALLY FORMING LIGHTNING IN THE CCAFS/KSC AREA

(2 May 2018)

1. Title: Unexplained Nocturnally Forming Lightning in the CCAFS/KSC Area

2. Definitions: None

3. Description:

The 45th Weather Squadron (45 WS) provides comprehensive weather services to America’s space program at Cape Canaveral Air Force Station (CCAFS) and NASA Kennedy Space Center (KSC).

Lightning is one of the most impactful weather phenomena to CCAFS/KSC, especially via the lightning watches and warnings and forecasting and evaluating the lightning Launch Commit Criteria (LLCC), which are a large set of complex weather rules to avoid rocket-triggered lightning to in-flight rockets. On rare occasions, thunderstorms form at night with no obvious cause. Although rare, these events can surprise 45 WS forecasters and lead to missed lightning watches, unpredicted LLCC violations, and unpredicted dangerous conditions. This project is to determine how frequent unexplained nocturnally forming thunderstorms occur in the CCAFS/KSC area, the conditions under which it occurs, and develop and test a prediction tool suitable for use in 45 WS operations.

The project should provide the following results:

1) An overall climatology of the unexplained nocturnally forming thunderstorms. This would likely be a map showing where the unexplained nocturnally forming thunderstorms formed in the CCAFS/KSC area.

2) Stratified climatologies of the phenomenon. The stratifications should show if there are any of the following preferences: over the ocean or over land, time of night, any preferred time of day, time of year, formation conditions, etc. Possible preferred formation conditions include the atmosphere being more unstable than normal, occurrence of land breeze front, occurrence of southeast convergent lines, presence of more pockets of warm water temperature in the near Atlantic Ocean, combinations of these factors, etc. The stratified climatologies may be maps and/or box and whisker plots of positive and null events along with hypothesis tests if there are statistically significant differences.

3) Develop and optimize a prediction tool using randomly selected positive and null events from develop cases. Verify and document the performance of that tool using randomly selected independent positive and null events.

4) Period of Performance: NLT 30 Sep 2020

4. Possible Approaches:

A large period of record will be needed to capture enough of these rare events for study. I suggest using ENTLN total lightning from 2010 onward. This should be superior to using cloud-to-ground lightning from NLDN for this project. Since these thunderstorms tend to be weaker with lower flash rate so using total lightning may increase the detection of these storms—they are more likely to produce no cloud-to-ground flashes, especially over the ocean, and so would be more likely to be missed by NLDN. In addition, if 30% of lightning is cloud-to-ground, then the 21 years of NLDN that would be used 1996-2017) would be equivalent to about 6 years of ENTLN. But we would have 8 years of ENTLN data (2010-2017).

NLDN detection efficiency performance became fairly stable in east central Florida in 1995, so we often use 1996 and onward NLDN to ensure reasonably consistent detection. Similarly, ENTLN became more reliable in our area for 2010 onward.

Duplicate the area of study used by Embry-Riddle Aeronautical University.

Use the evening RAOB for atmospheric stability information (23 UTC in the lightning season, 00 UTC at other times).

The analysis should be restricted to the lightning season in eastern Florida (May-Sep).

5. Deliverables:

1) Report documenting the work, including procedures used to generate those results.

2) Briefing to 45th Weather Squadron and KSC Weather Office summarizing the work.