Configuring weather events

You must be assigned a poweruser role to configure weather events.

A weather event is created by defining a set of criteria.

When significant weather occurs so that all the criteria of the weather event are met, the weather event icon is shown on the map. For example, in the case of the weather event in image Weather event "Thunderstorm", this happens when the defined criteria for both Lightning and CAPPI data types are met on the same geographical area (that is, overlapping on the map).

Log in to IRIS Focus as poweruser.
Select Places of interest > Events.
In the Events tab, select Create event.
Give the event a descriptive name, and a code.

The code is typically used in the context of aviation.
Select an icon from the drop-down list.

This icon is shown on the map when a weather event occurs.
Define the event criteria.
1. Select a product from the drop-down list (for example: Lightning, PPI, RAINN).
  
  The rest of the available event criteria depends on the product you select.
2. Define the other criteria for the product (for example: data type, thresholds).
  See Descriptions of weather event criteria.
  
  The list of data types shows data types currently available in your system.

You can select several products to add more criteria.

Vaisala recommends using up to 3 products as criteria.

All the criteria are included in the event using the AND condition. That is, all the criteria must be met in order for IRIS Focus to identify a weather condition as a weather event, and trigger alerts.

To use the OR condition, create another event and apply it to the same area of interest.

Lightning Threat Zone product can not be grouped with other products in an event.

Select Save.

Criterion Description

Minimum area

Minimum size of the event (in km²).

Weather events that are smaller than this do not trigger alerts.

This criterion is only applicable for products based on weather radar data.

This criterion means the size of the weather event on the map, not the size of a related area of interest.

If you set the alert area to 0 km², you may see lots of event icons for what is essentially one weather event, as every unconnected pixel exceeds the threshold and is counted as a separate event.

Minimum time

Defines how long the weather criteria must persist in an area of interest. IRIS Focus creates an alert if the event persists in an area of interest for the defined interval or longer. Weather events that last for a shorter time than the defined interval are ignored.

This criterion is only applicable for products based on weather radar data.

Vaisala recommends setting Minimum time value to 0. If the value is higher than 0, you will not get an alert for the first instance of the event on the area of interest. You will only get the alert when IRIS Focus receives the next instance of the product; this may be in 15 minutes or later, depending on the radar task schedule. This delay may lead to you missing an immediate alert for a significant weather event.

You must know your task schedule. In general, if all of your product criteria are based on the same task, set the Minimum time time to 00:00:00 so that only data from the same run are used.

Number of lightning strikes

Defines how many lightning strikes must occur within a certain time frame to trigger an alert.

Only applicable for TLP-based lightning data.

If you create an event for lightning where the alert is triggered after several strikes, then after the alert has been triggered, any further lightning strikes (even just one) will cause the alert to persist.

A lightning strike here refers to either a flash or a stroke, depending on the configuration on the TLP.

Time to clear alert after last strike

When there have been no lightning strikes for the time defined in this field, the alert is cleared.

If the criteria of a weather events includes both weather radar based products and TLP-based lightning data, the alert clearing time is defined by the weather radar data (default weather radar alert clear time is 20 minutes.)

Lightning threat zone

Defines how far in advance the area threatened by lightning will trigger an alert.

Only applicable for the Lightning Threat Zone product.

Task schedule considerations
On-demand products	IRIS Analysis products
IRIS Focus records when the event starts and continues monitoring for a defined time interval time to check when the time criterion is met.	You must define a time criterion that takes into account the frequency at which the products are sent to IRIS Focus.
IRIS Focus applies the event conditions to all tasks.	IRIS Analysis products are attached to a task, so the event criteria are applied only over those tasks used for IRIS Analysis product generation. IRIS Focus checks the area to see if a radar is producing the requested IRIS Analysis product.