PENNSYLVANIA TURFGRASS: Brad Jakubowski, Assistant Teaching Professor, Center for Turfgrass Science, Penn State University

Keeping an eye on the weather is something professional turfgrass managers have ingrained into our systems. Can I mow today? We check our phones for the most recent forecast. Should I spray today? We monitor dewpoints, humidity and temperatures. Will I pull the tarp prior to today’s game? We study the weather radar. There is a tremendous amount of weather information out there and nearly all of us have some form of a weather app on our phones, or a link to our favorite weather website, to help us make day-to-day management decisions. Let’s take a journey, to see what is out there and what information will help us make the best weather-based decisions possible.

Which app is the best?

Honestly, there is no one best app. It is important to find an app or a number of apps that provide you the most reliable and quickly available information. Basic Information that is important to have available with the least number of clicks would be: High and Low Temperatures (including overnight lows), Dewpoint, Relative Humidity, and Short-Term Weather forecasts. Intermediate information includes: Radar (Base and Composite Reflectivity), Satellite Imagery, and Severe Weather (especially lightning). Advanced information would be: Echo Tops, Vertically Integrated Liquid, Digital Storm Accumulation and Forecast Discussion.

Basic Information

When looking for basic information, it is best to have most or all important data on the first screen, or within one or two clicks from the first screen. That is often a good way to judge how well your app will benefit you over time. As an example, The National Weather Service includes much of the basic data (Figure 1). At a glance, you can get a good idea of what is happening now and what will happen in the immediate future. High and low temperatures provide a quick mental image of how the day (and night) may influence your maintenance plans. Winds, dewpoint and relative humidity provide a quick insight on irrigation requirements, disease potential, and infield skin management requirements.

It is beneficial to see both relative humidity and dewpoint together. Viewing only either limits your view of the big picture. For example, a relative humidity of 95% with dewpoints near 70 degrees indicate that less time may be spent scouting for wilt and instead used scouting for diseases. The same relative humidity with dewpoints under 30 may indicate a majority of the day may be dedicated for scouting wilt or watering an infield skin.

The Hourly Forecast – The Turf Manager’s Secret Weapon!

The Hourly Forecast on Weather.gov (Figure 2) is the turf manager’s secret weapon. In one image, a turf manager can make plans for multiple issues and tasks. For Example, The Heat Index: potential high heat indexes aids in planning for employee safety; Temperature and Dewpoint: Matched high overnight dewpoints and temperatures means extended leaf wetness and high disease potential. They also indicate heavy dew until at least 8am, which may require a syringe cycle to limit mower clumping, or to make sure greens are whipped post-cut; Wind Speed and Direction (Surface Wind): predicted light southerly winds meaning even higher probability for disease potential and dew, as well as for good spraying conditions in the early morning, but gusts in the teens starting around 11am; Relative Humidity: indicates conditions will be wet early, but dry quickly throughout the day; Sky Cover: indicates it will be partly cloudy throughout the day providing some relief, while Precipitation Potential indicate a 50% chance of rain throughout the day.

Intermediate Information

When making game-time decisions such as tarp pulls, or field evacuations, due to severe weather, radar becomes an important tool. There are numerous good weather radar apps available. Many are free, some require an annual fee of $US 10 to 50. Many of the fee-based apps offer expanded functionality, precision and overall quality of information. Regardless of cost, radar app selection should prioritize the type of reflectivity the radar images are based upon. There are two types: Base Reflectivity and Composite Reflectivity. Each time a radar transmitter spins, it sends out a microwave ‘sweep’ at different elevations to get a complete picture of all atmosphere elevations. A Base Reflectivity image represents only a single sweep of the radar transmitter. This means that near the transmitter the radar ‘sees’ is low in the storms and as distance increases the beam rises and can overshoot the core of heavier precipitation. Many High-Resolution (Hi-Res) radar images feature only Base Reflectivity sweeps.

Composite Reflectivity stitches together all elevation scans, in order, to create an image that represents a more complete picture of an incoming storm. These are often lower-resolution images and may be more pixelated. Figures 3 and 4 are of the same storm with the former being a Base Reflectivity image and the latter a Composite Reflectivity image.

Figure 5 shows the different reflectivity options you may have within a radar app, and again illustrates not all radar imagery is the same. So, when trying to make critical game-time decisions, a radar image using Base Reflectivity may grossly underestimate the significance of an incoming storm. When selecting a radar app, be sure investigate the types of radar images it provides, and be prepared to spend a few dollars for radar that will prove worthwhile in the future.

Satellite Imagery

There are numerous Satellite Imagery options as well. They provide visible cloud cover; infrared (the most common that we see), moisture content; and all-in-one maps that include a combination of radar, infrared, and weather station models to tell a complete weather story. Satellite images can give you a broader perspective of how the weather is behaving on a wider, more continental, scale. The images and loops illustrate air flow, cloud and moisture movement and overall dynamics of frontal systems. These large-scale images and video loops can help in longer-term planning. They can aid in project preparation and used as a tool to help protect fields when communicating with administrators that may be considering additional unexpected events during non-use days. It is useful to compare these images with regular weather maps to get a good working knowledge of fronts and changing weather systems.

Severe Weather

Lightning is the most critical facet of severe weather for sport turf managers. In 2022, one in five people struck by lightning were engaged in an outdoor sporting activity. Having an app that can provide you lightning information instantly or within a click on your phone is important. The lightning information from the WeatherBug app for Figure 6 only required a short scroll down and a single click. An old AM radio is also good to have on-hand as a back up lightning detector. Significant increase in crackles and static transmitted across AM radio bands are dependable indicators of lightning activity in the area. Old School!

Advanced Information

As we work towards becoming more proficient with understanding weather and being able to make better weather-based decisions, we find more advanced tools to help us. Echo Tops or Cloud Height is another function to help us assess the intensity of an oncoming storm. An Echo Top measures the overall height of a storm, which is an indicator of the strength of storm updrafts. Stronger updrafts make convective wind gusts and large hail more likely.

When several storms are on radar, the Echo Tops tool can point out the more severe storms and the direction they are travelling (Figure 7). This can be valuable information to report to the front office when asked about making a call on a game or whether the conditions will be safe to conduct a last-minute tarp pull. Another tool to assess the strength of a storm is Vertically Integrated Liquid (VIL). The VIL index measures how much water is being transported vertically throughout a storm cloud and is another indicator of a storm’s updraft strength. Taller updrafts tend to have higher values of VIL and are more likely to produce hail.

One more tool that can be used to help determine the total accumulation of a precipitation event is Digital Storm Accumulation. By allowing you to assess discrete accumulations over short periods of time, this tool may help you determine whether or not to pull a field cover for a particular rain event. Saving time and energy that could be used elsewhere and avoid unnecessary delays. This tool may also aid in determining the potential of a flash flood event in your area.

Summary

Technological advancements afford us incredibly convenient tools and information apps that support worker and clientele safety while improving our maintenance, irrigation, pest management, and playability decision-making. Take advantage of this opportunity by investigating these different apps and functions. Poll your colleagues, service providers, and blogs/forums to best experiment and discover what works best for you and your facility.

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