Written by, Basavaraj Amogi, Lav Khot, Sean Hill, April 8, 2024
AgWeatherNet (AWN) has rolled out 24-hour temperature inversion forecasts for 21 Mesonet tower stations. These stations (Figure 1) measure air temperature (Tair) at two distinct heights, i.e., 6.6 ft (2 meters) and 29.5 ft (9 meters) to detect low-level temperature inversions. In the past few years, AWN field team has deployed 47 towers in the areas critical to stakeholders with plans to have 100 such tower stations in coming years. As these towers accumulate at least one year of data, the inversion forecast will become operational. Among many uses, data and forecasts can help in early spring frost mitigation decision support in the fruit and berry crops.
How is it done?
For tower stations with at least one year of data, AWN has been providing the 10-day weather forecasts. Forecasted Tair are used for inversion strength (ΔTair) estimation by subtracting the temperature at 6.6 ft from that at 29.5 ft. These estimates can help in quantifying the expected warming effect using wind machines. During early spring frost events, wind machines are generally effective when ΔTair > 2 °F, and mixing can raise plant temperature by 50% of the inversion strength (read more). When ΔTair < 2 °F, warm air afloat is not sufficient to be pulled by wind machines and could just result in mixing up cold air. Thus, using conditions illustrated in Table 1, AWN has now rolled out tower station specific advisory to help growers in deciding when to or not to mix the air.
Table 1. Conditions to determine air mixing advisory within orchards.
| Scenario | Tair @ 6 ft. | Tair @ 29.5 ft. | Advisory |
|---|---|---|---|
| Inversion Scenario 1 | ≤ 32 °F | > 32 °F | Mixing could help |
| Inversion Scenario 2 | ≤ 32 °F | ≤ 32 °F | Mixing could make it worse |
| No inversion | Tair @ 6 ft. > Tair @ 29.5 ft. | Mixing not advised |
Accessing inversion forecasts
Steps to access inversion forecast for selected Mesonet tower station.
To view the inversion forecasts, users must log into the AWN website with their registered username and password. After navigating to the ‘Weather Dashboard’ under the ‘Weather’ tab,
users can select the nearest Mesonet tower station to view the temperature inversion data and forecasts.
If the forecasts are operational for the selected station, a detailed forecast with advisory will be displayed.
Acknowledgements
This operational product was realized through WSDA SCBG and USDA NIFA funded projects. The AWN team thanks development efforts of Aakash Shreshtha.
Contact
Lav Khot
Director, AgWeatherNet, Washington State University
lav.khot@wsu.edu
Basavaraj Amogi
Postdoctoral researcher, Washington State University
basavaraj.amogi@wsu.edu
Sean Hill
Application Systems Analyst/Developer
AgWeatherNet, Washington State University
sehill@wsu.edu
