Using Enviro-weather to look at freezing temperatures and temperature forecasts
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included
After a few weeks of warm weather and relatively quick degree-day accumulation, a low-temperature event may have affected crops throughout Michigan. Enviro-weather offers a few tools for evaluating potential damage on a regional basis.
During a potential freeze event, you can look at the latest temperature observations. These are available as “rollovers” on the map on the Enviro-weather homepage in most newer browsers or by clicking on a station dot. The latest observations for stations associated with a AgBioResearch station are also available on the AgBioResearch station pages (e.g., SWMREC, KBS).
For a look back in time, the Overnight Temperatures Report lists the hourly average temperatures at stations in a region. This can help you look at the duration and distribution of the event, as well as pointing out the actual temperatures. To look at past events (from a day ago or from years ago), select the option to “Change date range.”
In this report, all temperatures below freezing are highlighted. Note that this report also highlights warm nights (nights with temperatures above 70ºF), which may be of interest in summer.
For a look forward, the Overnight Low Temperature Forecasts lists the model results from the GFSX forecast for the nearest forecast locations; these are usually airports. The Late Afternoon Dew Point Report may seem slightly esoteric, and is only valid under certain conditions. When the forecast is for a clear night with low winds and stable atmospheric conditions, the temperature may fall as low as the dew point, but not farther, as the moisture in the air condenses and releases heat into the environment. In most events, there is movement of air masses, so these numbers are not relevant, but under special cases, they may drive the low temperature forecasts.