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Overview

Interpret your forecast

Alert Settings

Important information

Registration

Subscriber Access

Account Management




Overview

Four-day numeric forecasts of the following variables are updated twice daily for major towns and registered sites:

  • Heat Load Index (HLI)
  • Accumulated Heat Load Unit (AHLU)
  • Weather data; Black Globe Temperature (BGT), temperature, relative humidity, wind speed and direction, rainfall.

AWS data are also updated twice daily for major towns. These are based on BoM network of meteorological stations. In general, the AWS data for registered sites would also be updated twice daily. However, actual upload times may depend on a number of factors such as availability and quality.

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Interpret your forecast

The HLI is an indication of the heat load for each day. The AHLU, on the other hand, is the amount of heat that is accumulated by an animal when it is exposed to environmental conditions that are above its ability to maintain thermoneutral conditions.

1. Know your AHLU Level. You can use the RAP calculator to determine your AHLU level based on your site and type of cattle

2. Check your site forecast page. Values for the different AHLU Levels, as well as the HLI and other meteorological variables are displayed.

3. The four day forecast provided for all sites includes an hourly forecast for:

  • Accumulated Heat Load Units (AHLU)
  • Heat Load Index (HLI)
  • Temperature
  • Relative Humidity
  • Black Globe Temperature
  • Wind Direction
  • Wind Speed
  • Rainfall

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Alert Settings

Alerts are sent once a day, typically during the morning update to the CHLT website. The actual time when the alerts are sent depend on a number of factors, which include connection to initialising data and network connections. Alerts are generally sent at 3 AM.

AHLU Heat load indicator Cattle indications
1-20 Low risk No load or panting score 1
21-50 Medium risk Panting score 1-2
51-100 High risk Panting score 2-4
Over 100 Extreme risk Panting score 4

  1. Use the RAP calculator to determine the AHLU Level.
  2. Select the risk level that you want to be alerted to. Please note that if you select a ‘Low Risk Level‘ you are likely receive an alert every day.
  3. Select email and/or SMS preferences.

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Important Information

Temperature is not the main driver of heat stress and should not be used as the sole indicator for heat stress events. It is one of the factors that contributes to heat stress. In reality, the relationship between solar radiation and temperature, given as the black globe temperature, relative humidity and wind speed, all contribute to cattle heat stress where an event is determined by the duration of adverse conditions.

Adverse conditions refer to prolonged periods of high relative humidity and light winds. The temperature and solar radiation relationship is harder to explain, a temperature of 26 °C is itself not detrimental, however when combined with light winds, 66% humidity and full sunshine, the HLI can be upwards of 89 . If this situation where to continue with light winds and similar temperatures overnight a significant heat load event could occur without the daytime temperature getting above 30°C.

There is also the potential for rapid increases in the HLI causing acute heat stress over the course of several hours. This is particularly evident after short bursts of intense rainfall followed by clear skies and light winds. There are currently no alert thresholds for this occurrence and further research is required to determine rate of increase that can lead to acute heat stress.

Rainfall is presented as an indication of the rainfall that is likely to be received in the region. It is very difficult to forecast rainfall distribution (particularly summer storm rain) accurately for a particular location.

If you have received rain, the forecast HLI for your site may be underestimated due to the increased relative humidity at your site.

It should be noted that the rate at which the cattle recover is half the rate at which they accumulate heat load. This can sometimes cause the AHLU values to get ‘out of control’ and a significant weather event is required to reset the forecast AHLU to zero.

More research is required to better understand the relationship between the AHLU and feedlot cattle heat load.

As all cattle are different you need to select a relevant heat load threshold for your operation using the RAP.

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Registration

Site registration is free and only takes a few minutes. By registering your feedlot you will receive:

  • Twice daily, seven-day forecasts of maximum heat load, accumulated heat load and weather specific to your location. This is of particular benefit to feedlots that are some distance from the closest major town, as the meteorological parameters that influence the HLI and the AHLU forecasts can vary significantly over relatively short distances.
  • Optional automated alert system to warn you of up-coming high heat load events by SMS or email.
  • The option to up-load and view meteorological data and calculated HLI and AHLUs from your own weather station.

To register a site, the following are required:

  • NFAS accreditation number
  • Site name
  • Name
  • Email address
  • (Optional) Mobile number
  • (Optional) Alert preferences

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To register for the automated alert system, the AHLU and Risk Levels are also required. These may be calculated using the RAP Calculator.

After filling out the registration form, your information will be added to our secure forecast database and your site location added to our weather model. This may take 24 to 48 hours, longer if the request is sent over a weekend or public holiday. You will then be emailed a username and password. Once you have received these you can login to the registered users’ part of the site, where you can view your site specific heat load and weather forecasts information.

The first person to register a site is the default nominated CHLT site administrator. CHLT site administrators are able to view, add, update, and delete contact details and alert preferences of subscribers registered to the site.


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Subscriber Access

Registered users can be CHLT Site Administrators or Subscribers.

CHLT Site Administrators have control of the following information:

  • Add/Delete subscribers to the sites
  • Update contact details for all subscribers registered to the site
  • Update alert preferences for all subscribers registered to the site
  • Integration of AWS data into the site forecast (if available)

Subscribers have control of the following information:

  • Update contact details
  • Update alert preferences

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Account Management

Once logged in, the user has access to the My Sites > My Account page.

Your account page provides access to the site profile where CHLT site administrators can update details for subscribers registered to the site, while subscribers can edit their own details.

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