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Info
titleSaving & printing

 To save images during these exercises for discussion later, you can use:

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"Export" button in Metview's display window under the 'File' menu. This will also allow animations to be saved into postscript.

or

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titleUse the following command to take a 'snapshot' of the screen:
ksnapshot

 

Printing. If hardcopy prints are desired please use the printer at the rear of the classroom and only print if necessary.

 

St Jude wind-storm

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highlights

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The case study will look at one of several severe wind-storms that hit Europe in late 2013 (see handout of ECMWF article by Hewson et al, ECMWF Newsletter 139).

  • On the 28th October 2013 a small, severe wind-storm named St Jude in the UK, hit the UK & north-western Europe.
  • A total of 19 people were killed across Europe, 5 in the UK.
  • The return period of the event based on wind-gust observations show the 10yr return period was exceeded along the North Sea coast.

  • From the 23rd October, the ECMWF forecast predicted a greater than 70% probability of a severe wind event (greater than 60kt, 31m/s, at 1km) over southern England. A signal for the storm was evident from the 21st October.
  • On the 24th October, the UK MetOffice issued an amber alert for wind-speed across southern England placing the potential impact in the highest category.

  • The cyclone first appeared as a cold front wave, over the Atlantic, late on 25th October.
  • It deepened and moved rapidly east then northeast, with the storm centre reaching southern Sweden late afternoon on the 28th.
  • The most rapid deepening occurred between 06-12UTC on the 28th when the strongest wind gusts were observed.
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Outline of exercises

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Gliffy Diagram
nameexercise flowchart

 

Exercise 1. Visualise the ECMWF analysis of the St Jude storm

 

Handout

See map of observations of wind-gust during the storm and the timeseries of maximum gusts.

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Note
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titleObjectives
  1. Examine the map of wind-gust observations in the handout.
    Note the observed area of strongest windgusts and their intensity.
  2. How does the analyses compare with the observations?
  3. Understand the storm development and behaviour from the ECMWF analyses.

Starting up metview

Code Block
titleType the following command in a terminal window
metview

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titleMetview icons

For this task, use the metview icons in the row labelled 'Analysis'

 

Getting started

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titleGetting started
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Task 1:  Right-click the mouse button on the 'an_1x1.mv' icon and select the 'Visualise' menu item (see figure right)

After a few seconds, this will generate a map showing two parameters: mean-sea-level pressure (MSLP) and 3hrly max wind-gust at 10m (wgust10).

Use the play button Image Modified to animate the map and follow the development and track of the storm.

You can use the 'Speed' menu to change the animation speed (each frame is every 3 hours).

 

Task 2:  Right-click the mouse button on the 'an_1x1.mv' icon and select the 'Edit' menu item (see figure right).

An edit window appears that shows a number of lines of 'Metview macro' code. During these exercises you can change some of these to alter the parameters and plot types.

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titleTwo map types are available covering a different area

Image Modified

With mapType=0, the map will cover a smaller geographical area centred on the UK.

With mapType=1, the map will cover most of the North Atlantic

Change, mapType=0   to   mapType=1   then click the play button Image Modified at the top of the window (please ask if you are not sure).

Animate the storm on this smaller geographical map.

 

Task 3:  Change the fields plotted to include the wind arrows.

Make sure you have the Edit window showing.

Code Block
languagebash
titleAdd wind arrows to the plot:
#Define plot list (min 1 - max 4)
plot1=["mslp","wgust10","wind10"]

As above, click the play button and then animate the map that appears. You might also want to change the mapType back to 'mapType=1' to show the larger geographical area.

Discuss the storm development and behaviour with your colleagues & team members.

 

That completes the first exercise.

If time:

  • You are encouraged to explore the storm development and passage using the other parameters available on other pressure levels.
  • More explanation of how to use the Metview macro icons to alter the fields plotted are shown below.

If you prefer to see multiple plots per page rather than overlay them, please use the an_2x2.mv macro.

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titlePlot analyses in various layouts

Icon 'an_1x1.mv' produces a single plot on the page.

Icon 'an_2x2.mv' can produce up to 4 plots per page.

 

Info
titleChange plot fields

For the 'an_1x1.mv' icon, the plot contents can be changed by editing the plot1 variable in the macro as shown in the above first exercise.

To alter the plotted field, right-click and choose 'Edit'.

It is possible to overlay multiple fields by putting them in square brackets like this:

You will find a list of available parameters in the macro.

After editing the macro text, you can optionally save using the 'File' menu and 'Save'.

Display the plot by clicking:

Animate the plots in the display window by clicking

Info
titleChange plot appearance

 For the an_2x2.mv icon the number of maps appearing in the plot layout can be 1, 2, 3 or 4.  This is true of all the icons labelled '2x2'.

an_2x2.mv demonstrates how to plot a four-map layout in a similar fashion to the one-map layout. The only difference here is that you need to define four plots instead of one.

Right-click on the icon and select 'Edit'. Change the plot layout like this:

Note how some plots can be single parameters whilst others can be overlays of two (or more) fields.

Wind parameters can be shown either as arrows or as feather by adding '_f' to the variable name.

Two map types are available covering a different area.

With mapType=0, the map will cover a smaller geographical area centred on the UK.

With mapType=1, the map will cover most of the North Atlantic

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