Code Sleuthing

Yesterday, I discussed a problem that forecasters often have which researchers may be less aware of on a day-to-day basis: the sheer amount of change that can occur within a short time span in the atmosphere. To complement that perspective, today I'll discuss a challenge that researchers often face which forecasters may not deal with as often: the detective work and complexity of eradicating code bugs.

The Difference a Day Can Make

The Spring Forecasting Experiments all share the common goal of fostering communication between the research and forecasting communities, allowing each community to learn from the other. The past few days have provided an excellent lesson that, as a researcher, I sometimes forget. A day can make a world of difference when it comes to a forecast. Operational forecasters are no doubt shaking their head with the obviousness of this statement, but experiencing it firsthand gives me, and perhaps other researchers, a new appreciation for how quickly a forecast scenario can change. I'll give two quick examples from this week that illustrate this lesson.

9 May 2016

9 May 2016 turned out to be an extremely active day for severe convection, with tornado, wind, and hail reports stretching from Iowa and Nebraska south to the Texas/Oklahoma border. As of this writing, 25 tornadoes were reported. This count may fluctuate, as damage assessment is ongoing. The system that spawned this outbreak continues to cross the United States today, with 16 tornado reports occurring as of this writing. This system will likely warrant further study down the line, but I'd like to give a brief overview of our forecast considerations, review the experimental forecasts we issued yesterday in light of today's verification, and discuss our evaluation of the forecasts.

A view looking east from the roof of the National Weather Center in Norman, Oklahoma at 5:29PM CST. This supercell produced a brief tornado just east of Norman at 4:15PM CST.

Evaluating Nulls

Today was quite an active severe weather day locally. Our thoughts are with the people and families affected by today's tornadoes. However, today's SFE forecasts won't be evaluated until tomorrow, and today's evaluations focused on the relatively lackluster severe weather across Utah on Friday. Our participants were faced with a problem that has been discussed by the forecast evaluation community for years - how do you rate and compare correct null forecasts?

Question of the week: What do we do with these isochrones?

Week 1 of SFE 2016 is in the books, and overall it was a very successful first week. We had a great group of participants, who gave us good feedback despite the relatively marginal nature of the weather last week. Our domains focused on the eastern and southeastern United States, but we did have one day of forecasting in the west and some long-range south central plains forecasting towards the end of the week. Verification of these forecasts will commence tomorrow and, considering that Norman is in a tornado watch as I type this (~00Z 8 May 2016), we should have some weather to talk about tomorrow. At the end of each week, I'm going to discuss a question we explored throughout the week. This week, we'll talk about drawing isocrones, lines highlighting the four-hour period of highest risk for any given point.