Starting in AX-3.6, the WeatherService architecture for NWS advisories changed—this extension has minimal impact (single property, “Enabled”, and no other slots). For more details, see AdvisoryContainer. The remainder of this section applies to an AX-3.5 station only.
In AX-3.5, each NwsWeatherProvider has a child “Advisories Alarm Ext” extension. This provides for NiagaraAX alarms initiated by NWS-issued watches, warnings, and advisories of hazardous weather
conditions, for the locale of this provider. By default, this extension is enabled.
A child 
Alarm Properties container holds typical “Alarm Source Info” properties used to specify which alarm class is used, plus other standard alarm
parameters. See the following for more details:
Under the WeatherReport for this locale, the CurrentConditions component reflects a related alarm in its “Status” property, with its “State” property reflecting an enumerated value for
the hazardous condition. The “Weather Summary” property reflects a subject description received from the NWS.
Property sheet access of a AX-3.5 NwsAdvisoryAlarmExt shows its configuration properties and the child “Alarm Source Info” container, as shown in Figure 20.
Configuration properties are:
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Enabled
By default, this extension is enabled (
true). If set tofalse, NiagaraAX alarming does not occur from NWS watches, warnings, and advisories, and CurrentConditions remains unaffected. -
Alarm Properties
Contains typical “Alarm Source Info” child properties, two of which are described below.
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Alarm Class — (default is “Default Alarm Class”) Often, you create one or more alarm classes expressly for NWS related alarms, and specify one here. See the User Guide section “About alarm class” for alarm class details.
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Source Name — Specifies the “sourceName” seen in an alarm record, where the default value (as shown in Figure 20) results in the name of the parent WeatherReport (locale).
Remaining alarm properties operate as in similar alarm extensions for devices or points. For more details, see “About alarm extension properties” in the User Guide.
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Urgency
Determines the sensitivity of alarming. NWS advisories include a “Urgency” property, with enumerated values reflected in choices available in the drop-down control, in order of descending priority (highest at top):
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Immediate
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Expected
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Future
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Past
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Unknown
This property determines which incoming advisories will trigger alarms. Only advisories with an urgency equal or higher than the chosen value generate an alarm. (The NWS issues advisories for non-emergency conditions, just like a weather forecast—this allows filtering on urgency level).
Note that among various alarm data facets (fields) in an alarm record, an “nwsUrgency” facet will reflect one of the values above. For related details, see the next section About NWS alarms.
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An alarm from the AX-3.5 Advisories Alarm Ext (NwsAdvisoryAlarmExt) results in a changed iconic Current Weather view (Px) as well as an alarm record with NWS data. See the following section, NWS data in alarm record.
Also see Current Weather view (Px) effects.
An NWS-initiated advisory in a AX-3.5 system results in an Offnormal alarm with several NWS-specific facets in its “Alarm Data”, as shown in Figure 21 (facet “nwsDescription” reduced in this example).
Included in the Alarm Data of the alarm record are the following:
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msgText — the enumerated value of the CurrentConditions “state” property
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nwsCertainty — the enumerated value of the “Certainty” property received from the NWS, for example “Possible”, “Likely”, and so on.
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nwsDescription — text string from the NWS that provides a complete description of the advisory.
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nwsExpires — date/timestamp of when the NWS advisory expires.
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nwsInstructions — text instructions from the NWS on what to do because of this advisory.
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nwsSeverity — the enumerated value of the “Severity” property received from the NWS, for example “Moderate”, “Minor”, and so on.
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nwsUrgency — the enumerated value of the “Urgency” property received from the NWS, for example “Expected”, “Future”, and so on. Corresponds to the “Urgency” property among the NwsAdvisoryAlarmExt properties.
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sourceName — typically the name of the parent WeatherReport (locale), such as “Richmond”, etc. (unless “Source Name” under the “Alarm Properties” container has been edited from defaults).
Once all NWS watches, warnings, and advisories have been canceled or expired, the NwsAdvisoryAlarmExt alarm source returns the alarm to a normal condition.