Data Collection Strategies

Selecting a storm

The OC will choose storms based largely on coordination of data collection among all projects ongoing in the Hazardous Weather Testbed. During many events this will require an open phone line between the developmental lab and the HWT room. In general, storms will be sampled based on the following order of priority:

1. Storms being scanned by NSSL's multi-use phased array radar
2. Storms being scanned by the SMART-Radar
3. Storms in the CASA network (generally between Chickasha, OK and Lawton, OK)
4. Any other potentially tornadic or hail-producing storm within 150 miles of Norman, OK
5. Storms that are subject of HWT/EWP experimental probabilistic/threat-area warnings
6. Any other storms in the CONUS as outlined below

If no other HWT activities are collecting data, SHAVE is free to choose any storms of interest over the US. The OC should target storm types that have not been significantly sampled during the project. We desire to collect a diverse dataset of storm types in varying environmental conditions. Some variations may include:

supercells splitting supercells, especially left-moving supercells quasi-linear convective systems bow echoes derechoes "pulse" thunderstorms that form in a high-CAPE low-vertical-wind-shear environment storms that form in cold-core upper air systems

This experiment is blind with regard to whether or not a severe weather warning has been issued by the National Weather Service for a particular storm - we will sample both warned and unwarned storms. Data will be made available to those NWS offices that desire to examine the data in real-time. We would encourage those NWS offices that do use our data feed, however, to continue to collect information from their own storm spotter networks as per their normal operations. There is no guarantee that SHAVE will sample storms in a given NWS County Warning Area on a particular day, and even if we do so it is possible that we will only do so for a short time or may miss something that a regular spotter might report.

Collecting data on a storm

• the OC logs the relevant information about storm type
• the OC will determine a cross-section, usually perpendicular to the storm path, along which targets will be called. They will monitor this cross section to ensure that the storm has cleared the area before data collection starts along that line. The phone calls should be made as soon as possible following storm passage, however, in order to minimize errors in estimated time from the call target.
• the team will coordinate to collect data points that are spaced approximately 1 km apart along the cross section line, using the survey form.
• as the storm continues to move, the OC will determine a new cross-section to collect data and the process repeats.

Hail data collection examples

• Slow-moving supercell
• Fast-moving linear system

Operating over a populated area When storms are over populated areas, the databases of phone numbers available in Google Earth and Delorme Street Atlas Plus are very useful for finding verification targets. In this situation, the OC's job is primarily to determine the storm of interest and to set up cross sections for examination. They will monitor the progress of the team to complete each cross-section and select a new cross-section. Most of the relevant data concerning call history, hail reports, and current cross-section should be available on the Collaboration Display.

Operating over a rural area

When storms are over rural areas for which county directory information is available, it is more challenging to collect data. The OC or a designated assistant OC will correlate the non-digital or web site sources to a geographic display and enter these phone numbers into the call queue and/or pass them to the data collection team via Google Earth. The results will still be available on the Collaboration Display, but the team will rely on more centralization to determine where to collect data.

Using on-line media sources Collecting information about wind damage and/or tornado damage is very difficult in the immediate minutes after a storm passes. For this reason, damage locations might be easier determined by monitoring local media sources, such as streaming television and radio coverage, local newspaper sites, and national news and photo wires. Damage data points collected this way should be entered via the standard survey form. Mining of media data sources and follow-up phone calls to fill in gaps in damage swaths may also be conducted the day following a major event.

Quality assurance

All data collection entry form entries should be checked for errors immediately before submission. Project participants are enouraged to look through the database during down time to check for errors and make corrections. Adjustments to estimated times are the most frequent source of error, though sometimes location information can be mis-typed. Some "down" days may consist primarily of data quality control.