Monday, May 4, 2020 6 P.M.
First, our local weather
A weak low pressure system will work its way across the southern plains tonight and across Kentucky tomorrow. It’ll bring us some rain tonight (after Midnight) into tomorrow. Any rain after mid-morning tomorrow will be very light. Total rainfall is expected to be in the quarter inch to half inch range. Cooler air filters in tomorrow and we’ll see below normal temperatures likely through the weekend, at least.
Computer models and forecasting, part 2
After the Army built the first eniac (computer) from 1943-6, the Navy decided to build a second one in cooperation with the private sector. A group of mathematicians and meteorologists was chosen to complete the project. Why meteorologists? Two reasons: first, the earliest computers had no what we now call “software.” The machine had to be built to solve one single problem. It would have no other use since the “software” had to be built into the machine, Second, the project leader was John von Neumann, a mathematician. Von Neumann, however, was familiar with Richardson’s work from the 1920’s. (previous post)
He figured the team had an already-solved problem. All they had to do was build the machine to perform the calculations. Thus, he reasoned, meteorology had the problem and a pre-existing method to solve the problem. That would save a lot of time.
In reality, Richardson had made some mistakes and faulty assumptions. The meteorology team spent a lot of redoing the physics and methodology before the machine could be built.
Finally, in 1950, in a large lab at Princeton University, eniac produced the world’s first non-military computer “output” – a 24 hour numerical weather forecast. It took the machine 24 hours to produce it.
Within two years, the computer time dropped to two hours. The world of “computer weather forecasting models” accelerated from there. Improvement has been immense.
Computer modelling has expanded over the years. Virtually anything you can think of is under the scrutiny of various models. Weather has had 70 years working on the problem and we still make mistakes. Same goes for other models you may hear mentioned. Which brings up today’s most talked about model – the coronavirus model. The conversation continues tomorrow.