Vorticity, and Why We Need Weather People

The job of a typical weather person may seem pretty easy in many aspects. After all, we only have to be correct 50% of the time and we still have a job! Better yet, there are super powered computer models being maintained by the government that can do the same analysis a human could do in a fraction of the time, with hundreds of times more detail and resolution. If weather forecasters are only right half the time and there are already computers ready to replace them, why did Ag Informatics choose to hire a full time weather geek like myself? More importantly, why would you (the grower) want to have a team of meteorologists and ag-engineers aiding the decisions you make on your farm when you can get your weather and ag reports from the news and radio?

One reason why we need trained meteorologists is vorticity. To the general public, vorticity may just sound like a fancy word but to a weather geek it means so much more. Vorticity is a measure of spin in the atmosphere. For the hardcore nerds out there, vorticity is mathematically defined as ‘del cross V’, a concept known throughout engineering as the cross-product. Scientists have proved that vorticity is closely related to fronts, cyclones, and the inclement weather we know is associated with fronts. We can approximate vorticity throughout our atmosphere at various levels and from that data, extract out information about other variables such as cloud cover and precipitation. A trained meteorologist can take a quick look at a 500mb vorticity map and create a reasonable estimation of surface weather in just a few seconds.

With that in mind, let’s take a look at the current 500mb geopotential height and absolute vorticity. The three major cyclones of interest are relatively easy to spot here. They have been marked with a yellow X. There is a high pressure ridge positioned in the center of the country that will lead to an overall warming trend over the next 6 days. A small shortwave trough ( small X near the Rockies ) is starting to amplify and will affect our region in the next few days.

VALID: 1PM Tuesday October 21st

Lets look at the forecast for Thursday at 1PM and see the development of the three cyclones…

The key synoptic (large) scale feature is the high pressure system setting up in the heart of the country which will lead to clear skies and warm temperatures this weekend. Afternoon high temperatures for Saturday, Sunday, and Monday may be in the lower 70s. The two east most cyclones have moved out of range and will not be affecting the midwest. The large cyclone over the west coast will continue to amplify and will eventually reach Illinois early on next week. Let’s take a look at the map for Saturday afternoon to confirm the forecast of clear skies and warm temperatures this weekend!

The key thing to notice here is that there are no cyclones anywhere near the midwest. The west most cyclone will begin to amplify and will probably be the next significant chance of precip here in the midwest, progressing eastwards slowly until affecting Illinois later late in the evening on Monday October 27th.

Here is an animation of what these forecast maps look like in sequence. The images are at 12 hour intervals going from 1PM on 10/21 to 1PM on 10/25. 

The goal at Ag Informatics is to provide the best weather data for each individual field within your operation. We provide weather data that goes 12 years into the past and 14 days into the future. Our weather forecast database is built by integrating many weather models together to create an accurate forecast for your field. The data fueling the images shown in this post come straight from the same sources used in our weather data API!

Contact me at bill.turner@ag-informatics.com to ask more about how Ag Informatics can use our weather data to help your farm operations or contact info@ag-informatics.com for more general enquires!