[EAS] NWS event criteria change?

[Botterell, Arthur@CalOES]

This was a challenge we faced in designing CAP... the common practice of conflating several dimensions of priority into a single scale.  We unpacked them as separate values for Urgency (timeframe), Severity (impacts) and Certainty (probability).

Any scale that combines those factors into a single list will occasionally encounter ambiguous cases.  It's one of several built-in problems with SAME-based alerting schemes.

Art

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From: EAS <eas-bounces at radiolists.net> on behalf of Herb White <hwhite72 at gmail.com>

An advisory denotes high probability of an event of less serious conditions than a warning event and one that can cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property.

Sincemuch of the countryhas begun the winter season now is a good time to review some NWS winter weather definitions pasted below from page 4 of the NWS Winter Weather Products Specification at
https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.nws.noaa.gov%2Fdirectives%2Fsym%2Fpd01005013curr.pdf&data=01%7C01%7Carthur.botterell%40caloes.ca.gov%7Cbf2b3f4e114c4339ca6b08d4212fa83a%7Cebf268ae303647149f69c9fd0e9dc6b9%7C1&sdata=6t6oTX1%2FOhTz8TMppeHQd95UG4TDvEijY83D841YHwA%3D&reserved=0:

3  Multi-tiered Concept. The NWS winter weather warning program will use, when
appropriate, the multi-tiered concept to increase public awareness and promote a proper
response to the impending hazardous winter weather event. Generically, the multi-tiered
concept is: Outlook, Watch, Warning/Advisory.

3.1  Outlook. An outlook is used to indicate that a hazardous winter weather event may
develop. It is intended to provide information to those who need considerable lead time to
prepare for the event.

3.2  Watch. A watch is used when the risk of a hazardous winter weather event has
increased, but its occurrence, location, and / or timing is still uncertain. It is intended to provide
enough lead time so those who need to set their plans in motion can do so.

3.3  Warning / Advisory. These products are issued when a hazardous winter weather event
is occurring, is imminent, or has a very high probability of occurrence. A warning is used for
conditions posing a threat to life or property. An advisory is for less serious conditions that
cause significant inconvenience and, if caution is not exercised, could lead to situations that may
threaten life and / or property.

Herb White
Program Analyst | Dissemination Projects Contract Support
NOAA National Weather Service | Office of Dissemination

On 12/10/2016 10:01 AM, Mike McCarthy wrote:

>The following is a an except from this morning's local WFO AFD.

>Start paste...

>....This event absolutely does
>not fit the conceptual model of a warning worthy snowfall event
>locally, so given the expected very long duration of the event and
>primarily light to moderate snowfall accumulation rates, we`re
>opting to upgrade the winter storm watch to a winter weather
>advisory.

>End Paste...

>Even my rather informed nature to NWS products was jilted by seeing this
>rather plainly stated sequence of winter storm event threat levels. (FWIW,
>I very much appreciate Gino Izzi's plain speaking in his AFD's....)

>So when did an advisory become a higher level event than a watch?  I've
>always understood storm event hierarchy as:

>Advisory (lowest...potential exists)
>Watch (prepare)
>Warning (highest...react accordingly)

>That is the case with blizzard, wind chill, high wind, and others if I am
>not mistaken.  More over, 11.31(e) contains no SAME/EAS message types for
>advisories. Only watches and warnings/emergencies (call to action
>messages).

>And with 40+ years of ingraining in the public's mindset that there are
>two significant threat levels (Watch and warning), the public's perception
>of an "advisory" message is something lower than a "watch".

>Can you say--- confusing....?!!

>MM

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