Changes to the Severe Weather Outlook
MetService is planning to make changes in the near future to the Severe Weather Outlook that forms part of our severe weather warning service. The reason for the change is to improve the clarity of the charts and make it easier to determine which threat area applies to which day.
What is the Severe Weather Outlook?
The Severe Weather Outlook provides advice on upcoming severe weather (covering heavy rain, heavy snow or strong winds) over the four-day period starting ‘the day after tomorrow’ (days three through six of the forecast period). The Outlook is a ‘heads up’ that we can see potential severe weather coming, but there is some uncertainty about what might happen and where.
Currently, the Severe Weather Outlook comprises a single image containing all potential severe weather areas on one map of New Zealand covering four days. The image is accompanied by a text statement describing the upcoming situation and threat areas. Both the image and the text include an indication of the Meteorologist’s confidence (low, moderate or high) in the severe weather being forecast.
What’s changing and why?
There will be phases to the changes of the Severe Weather outlook with the first phase seeing a split of the current single image into four separate images – one for each outlook day. Each daily chart will be accompanied by a text statement relevant to that day. The new charts will also use standardised colours for each weather type (rain, snow or wind) ensuring a consistent use of colour for all charts and issues of the Outlook.
The reason for the change is to improve the clarity of the charts and make it easier to determine which threat area applies to which day. Currently, the Outlook chart can be cluttered and confusing to read when the forecast period includes a lot of severe weather. There is also no consistency in the use of colour for the areas depicted. The planned change will simplify the charts, making them more readable and easier to interpret with a consistent use of colour.
Examples
Examples of the current and planned format of the Severe Weather Outlook are outlined below including key attributes of each.
Example of current web layout (Before):
Key attributes:
- One large text statement and one image, both covering all four days of the outlook period
- Chart can show many areas of potential severe weather, with different colours used (at the discretion of the meteorologist, but in general with no consistency from issue to issue and no alignment of colour to weather type or confidence)
Severe Weather OutlookCyclone Gabrielle expected to bring significant severe weather to northern and central New Zealand from Sunday onwards. Cyclone Gabrielle is expected to move southeastwards out of the tropics and lie north of the country by Sunday. East to southeast winds will strengthen significantly over northern parts of the North Island during the weekend, and there is high confidence of severe gales for Northland, Auckland and Coromandel Peninsula from Sunday through Tuesday. Also from Sunday through Tuesday, there is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, and Gisborne. This high confidence extends to Bay of Plenty, Gisborne and easternmost Waikato on Monday and Tuesday, when there is also low confidence for Taranaki, Waitomo, Taumarunui, and the remainder of Waikato. On Tuesday, southeast gales are forecast to extend to central New Zealand, and there is high confidence that they could become severe, as indicated on the chart. Easterly gales are expected to extend to the Chatham Islands from Tuesday into Wednesday. Finally, heavy rain is also likely on Tuesday about central areas from Marlborough to eastern Wellington and Wairarapa, and there is moderate risk that accumulations could meet warning criteria. Very large waves and a storm surge are expected to affect northern and eastern coastlines from Northland to Gisborne from Sunday into Monday, spreading south to Marlborough Tuesday.
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Example of planned web layout with images (After):
Key attributes:
- Four charts, each with an accompanying text statement – one per day
- Single situation statement for any key messages relevant to the entire Outlook period
- Separate and consistent use of colour for each weather type (rain, snow, wind), or multiple types, with consistent line style for confidence level
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Severe Weather Outlook Cyclone Gabrielle expected to bring significant severe weather to northern and central New Zealand Cyclone Gabrielle from Sunday.
Sun 12 Feb Cyclone Gabrielle is expected to move southeastwards out of the tropics and lie north of the country by Sunday. East to southeast winds will strengthen significantly over northern parts of the North Island during the weekend, and there is high confidence of severe gales for Northland, Auckland and Coromandel on Sunday. There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, and Gisborne. Very large waves and a storm surge are expected to affect northern and eastern coastlines from Northland to Gisborne.
Mon 13 Feb There is high confidence of east to southeast severe gales for Northland, Auckland and Coromandel Peninsula on Monday. There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, and Gisborne, which also extends to Bay of Plenty and easternmost Waikato. There is also low confidence for Taranaki, Waitomo, Taumarunui, and the remainder of Waikato. Very large waves and a storm surge are expected to affect northern and eastern coastlines from Northland to Gisborne.
Tue 14 Feb On Tuesday, there is high confidence of severe gales for Northland, Auckland and Coromandel Peninsula. Southeast gales are forecast to extend to central New Zealand, and there is high confidence that they could become severe. There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, Bay of Plenty, Gisborne and easternmost Waikato. There is also low confidence for Taranaki, Waitomo, Taumarunui, and the remainder of Waikato. Heavy rain is also likely on Tuesday about central areas from Marlborough to eastern Wellington and Wairarapa, and there is moderate risk that accumulations could meet warning criteria. Very large waves and a storm surge are expected to spread south to Marlborough.
Wed 15 Feb The risk of severe weather becomes minimal on Wednesday, as Gabrielle moves away from the country.
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Example of Severe Weather Outlook emails, text only (after):
Key attributes:
- Four text statements – one per day
- Single situation statement for any key messages relevant to the entire Outlook period
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MetService Severe Weather Outlook Issued at 11:30am Fri 10 Feb 2023 Sunday 12 February 2023 There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, and Gisborne. Very large waves and a storm surge are expected to affect northern and eastern coastlines from Northland to Gisborne.
There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, and Gisborne, which also extends to Bay of Plenty and easternmost Waikato. There is also low confidence for Taranaki, Waitomo, Taumarunui, and the remainder of Waikato. Very large waves and a storm surge are expected to affect northern and eastern coastlines from Northland to Gisborne.
Southeast gales are forecast to extend to central New Zealand, and there is high confidence that they could become severe. There is high confidence of significant heavy rainfall over Northland, Auckland, Coromandel Peninsula, Bay of Plenty, Gisborne and easternmost Waikato. There is also low confidence for Taranaki, Waitomo, Taumarunui, and the remainder of Waikato. Heavy rain is also likely on Tuesday about central areas from Marlborough to eastern Wellington and Wairarapa, and there is moderate risk that accumulations could meet warning criteria. Very large waves and a storm surge are expected to spread south to Marlborough.
An update will be issued by 4:30pm Sat 11 Feb |
More information
If you would like more information about the planned change, please contact:
severeweather.manager@metservice.com