Domain Decisions

When severe weather is imminent across the country, forecasters at the SPC must consider all of the possible areas. However, here at the SFE where we are considering multiple experimental NWP ensembles, we have to select our domain of interest. When the severe weather is spread across an area larger than a single domain, we must choose which region we want to focus on. To do this, the facilitators consult not only our experimental numerical weather prediction models, but also the upper-air data collected by radiosondes. Typically, the domains have quite a bit of overlap, but on days like last Thursday (17 May), a decision must be made between two very different areas.

After evaluating the previous day’s forecasts, the first forecasting activity for the current day that participants do is the hand-analysis of upper air maps at six different levels: 250 mb, 500 mb, 700 mb, 850 mb, 925 mb, and the surface. This activity ensures that participants get their hands onto the observed data, and develop a thorough understanding where a convectively favorable environments will occur. A map discussion follows (pictures of which can be found on the NSSL Flickr account) where participants share what they’ve learned through their contours. On Thursday, the conversation was far-reaching, as we had to decide between two domains that had very little overlap:

The two potential areas of interest for 17 May 2018, with the eventual selected domain highlighted in green.