Warnings

Which are best impact or threshold based weather warnings?

ChatGPT said:

The choice between impact-based weather warnings and threshold-based weather warnings depends on the context and the needs of the users. Both have advantages and limitations, but modern meteorological services are increasingly favoring impact-based warnings due to their ability to communicate risk more effectively. Here’s a comparison:


Threshold-Based Weather Warnings

Definition:

Warnings are issued when weather conditions reach or exceed predefined thresholds, such as a specific wind speed, rainfall amount, or temperature.

Advantages:

  1. Simplicity: Easy to understand and implement since the criteria are fixed.
  2. Consistency: Standard thresholds ensure uniformity across regions.
  3. Objectivity: Focuses purely on measurable weather parameters.

Limitations:

  1. Context Ignored: Doesn’t account for local vulnerabilities or varying impacts. For example, 50 mm of rain might cause flooding in urban areas but not in rural ones.
  2. Over- or Under-Warning: Fixed thresholds may result in warnings for areas where impacts are minimal or miss areas where impacts could be severe despite not meeting the threshold.

Impact-Based Weather Warnings

Definition:

Warnings are issued based on the anticipated impacts of weather events, considering factors such as vulnerability, infrastructure, and local preparedness.

Advantages:

  1. Relevance: Focuses on what the weather will do rather than just the weather itself, making it more user-oriented.
  2. Localized: Takes into account local conditions, infrastructure, and vulnerabilities.
  3. Improved Decision-Making: Helps individuals, businesses, and authorities better understand the risks and take appropriate actions.
  4. Avoids False Alarms: Reduces unnecessary warnings for events unlikely to cause significant harm.

Limitations:

  1. Complexity: Requires more data and analysis, including vulnerability assessments and real-time modeling.
  2. Subjectivity: Impact predictions may involve assumptions that are open to interpretation.
  3. Communication Challenges: Effectiveness depends on clear communication of risks, which can be harder to standardize.

Comparison

AspectThreshold-Based WarningsImpact-Based Warnings
FocusWeather conditions (e.g., wind speed, rainfall).Potential impacts on people and property.
User RelevanceLess tailored to specific needs.Highly relevant and actionable.
FlexibilityFixed and rigid thresholds.Adaptable to local context.
ComplexitySimple and easy to issue.Requires more analysis and resources.

Which is Best?

Impact-based weather warnings are generally better, as they focus on what matters most: the effect on people, property, and the environment. These warnings enable better preparedness and response by tailoring information to the situation’s real-world consequences.

However:

  • Threshold-based warnings are still useful in certain contexts where simplicity and consistency are needed, such as for scientific purposes or in regions where detailed impact data isn’t available.

The trend among meteorological services globally, including the UKUK The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy, the National Weather Service (US), and others, is to shift toward impact-based warnings to improve public safety and response.

Artificial Intelligence, Warnings

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1 Aug 2024 – Thunderstorms

Winchester High Street – 1 August 2024 (courtesy BBCBBC The British Broadcasting Corporation (BBC) is the national broadcaster of the United Kingdom, based at Broadcasting House in London. It is the world's oldest national broadcaster, and the largest broadcaster in the world by number of employees, employing over 22,000 staff in total, of whom approximately 19,000 are in public-sector broadcasting.)

Below are some of the images that I posted on Twitter concerning the heavy rain and flooding from thunderstorms across parts of southern England on Thursday. Although the UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy scored nul points with a yellow warning for thunderstorms on the previous day, the warning they issued for Thursday was fully justified 👍.

Flooding, Thunderstorms, Warnings

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The discriminatory impact based warning system

The above is an amber warning issued for Brighton and Hove, East Sussex, Kent and West Sussex for Monday the 22nd of January 2024. It’s a perfect example of how winds in Scotland have to gust in excess of 80 mph before an amber warning is issued there, but only 70 mph in England. Below is the Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy’s own UKV model for 06 UTCUTC Coordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT). on Monday morning, the spot values clearly show gusts of 69 kts across NENE North East Scotland and 61 kts across the coast of Sussex.


The impacts on a roof or chimney stack are identical, the last time I checked, the laws of physics are exactly the same in Brighton as they are in Kirkwall, and a 70 mph gust that removes slates off a roof in either place will have the same consequences if it falls on someone’s head. But impact based warnings are weighted in favour of population density, and hence the reason why the 69 kt gust is viewed as less ‘impactful’ in the NE Scotland than the 61 kt gust in Brighton. Completely balmy. Impact based warnings are discriminatory, and not for the right reasons. Bring back threshold based warnings.

NSWWS, Scotland, Warnings

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UKMO Warnings Viewer

I wrote this warnings viewer to display the latest warnings issued by the NSWWSNSWWS The National Severe Weather Warning Service is a service provided by the Met Office in the United Kingdom. The purpose of this service is to warn the public and emergency responders of severe or hazardous weather which has the potential to cause danger to life or widespread disruption. This allows emergency responders to put plans into place to help protect the public and also allowing the public to make necessary preparations. at the Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy several years ago. But since then, time and HTML wait for no man, and I’ve spent some time performing radical surgery on it to get it working again. The UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy are planning to publish an API for it soon to make this process much easier, but my request for a key has been denied it’s not for personal use, apparently it’s only for ‘business to business’ users whoever they are.
The parsing of the HTML Is rather tricky, but I think I’ve just about got it more-or-less cracked, except for occasions when there are multiple maps for a warning.
Why do it? Because like Everest it’s there!
I can now archive warnings and revisit them. Having access to the shapefile for the warning areas means I can zoom in on the map if needs be, and there’s no reason why in the future I couldn’t overlay snow depths, wind gusts, rainfall & temperature values on it for verification purposes.

Software, UKMO, Warnings

UKMO Warnings Viewer Read More »

They’re in trouble when Berry Head and the Needles are in the list

It’s certainly been, and still is across the west of Wales, a very windy day with coastal gales and some strong gusts on the cold front, but nothing very exceptional for a late November day. There were gale or severe gale force winds and comparable gusts for several consecutive days last week in the Northern Isles without any warning at all. You know the Met Office are trying to justify their warning when they roll out gusts from non-standard exposure, cliff top sites like Berry Head and the NeedlesNeedles A non-standard WMO class 3 anemograph site, stuck on top of a near 300 foot limestone cliff, on the Isle of Wight. Old battery. What tickles me is the UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy are loathed to mention wind speeds from mountain sites such as CairngormCairn Gorm Cairn Gorm (Scottish Gaelic: An Càrn Gorm) is a mountain in the Scottish Highlands. It is part of the Cairngorms range and wider Grampian Mountains. With a summit elevation of 1,245 m (4,085 ft) above sea level, Cairn Gorm is classed as a Munro and is the seventh-highest mountain in the British Isles. but have no qualms at all using readings made atop a 300 foot chalk cliff.

As for today’s rainfall totals [06-18] nothing that excessive either, even if most of it was on the front itself. The warning mentioned 10 to 15 mm in 1 to 2 hours and 20 to 25 mm in a few places, both too excessive. There was just 0.2 mm here in the NENE North East of Scotland.
If the UKMO can take a hard line with the issuing of warnings in Scotland why can’t they do the same for everywhere else?
It seems we’re fast becoming a Nanny State even with regard to weather.

Rain, UKMO, Warnings, Wind

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12 UTC analysis

Intense squall line across the SW of Wales

There may well have been a mini-tornado in Wales this morning, but the highest guts from the stations in the SYNOPSYNOP SYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. network are rather underwhelming, and none of them higher than the 76 mph gust at the Mumbles yesterday when there was no yellow warning in force. Line convection on a cold front like we’ve seen today is not an uncommon occurrence across IONAIONA Islands Of North Atlantic. Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK. at any time of the year, but does that mean from now on we’ll see the Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy issue a combined Yellow warning for heavy rain and strong winds each time that they do?

Analysis, Rain, UKMO, Warnings, Wind

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