What’s New April 2018

We’ve been working on some updates over the past weeks which have been available to site Patrons (patreon.com/wxcharts) during development.

These changes are now live and available to all…so whats new?

New Models

With a second server now live we’ve started the process of adding some new models….

UKMO

The most requested by patrons was UKMO data – unfortunately the UKMO do not make much of their data available for free (unlike most other major Met services) – but we’ve added what we can find.  This is MSLP and 500 hPa information at hours t+72, t+96 and t+120.

CMC – CANADIAN

Next on the list of requests was data from the CMC (Canadian Met Centre) Global model. Most seem to know this by the name of GEM – for Global Enviromental Model, but as far as we can make out the correct name for this source is GDPS – Global Deterministic Prediction System.  Charts for this model update twice daily and are made for all continental, regional and country sized regions.  A wide selection of variables are available with the exception of convective parameters such as CAPE and Gusts.

 

Both the UKMO and CMC global model charts can be found by clicking the relevant selection in the top left and part of the control column:

New Controls

With a growing list of model sources (and more on the way) the old version of the left hand control column was getting short on space, especially on smaller screens.  Because of this we’ve opted for an accordion style system where only one of the “MODEL”, “REGION” or “CHART” lists can be viewed at one time.  Just click on the one you require to expand it.  

We also plan to develop an alternate grid-style selection system in the near future.

Convective Overview

To go alongside our existing main overview (cloud, precip, pressure, temperature) and winter overview (precip, thickness, snow depth, pressure) charts we’ve added a third overview chart, called the “Convective Overview).  This shows precipitation rate alongside contoured cape and either Bulk Shear barbs or 500 hPa contours depending on region size and availability.

The Convective Overview chart is available for all models that have the minimum of Precip rate and Cape available.

Locations now on GIFS

If you choose to show the location overlay, these will now be included when you make a GIF.

We plan to add a share/capture feature of static images which will merge the base chart and location overlay in the near future.

Coming soon…..

We plan to continue adding further model options and will be polling patrons soon to decide what should be next.  Available options will include global ICON or regional COSMO data from the DWD, RDPS (regional det prediction system) or Ensemble data from CMC, Finnish Hirlam and Global ARPEGE from Meteo France.

We also plan to start adding more models to our database to allow creation of meteograms / skew-t plots.

There are also further new charts in the pipeline, and we haven’t forgotten about Observations – we’ll be returning to these to add more chart options and historical point plots.

Get Involved

We need help to fund our two Servers – with rental costs now nearly £500 per month.   To have a direct say in how the site develops please consider becoming a site Patron by heading to http://patreon.com/wxcharts

The site is run on a non-profit basis in our spare time.  Any income we make we plough back into the running of the site. We’re currently eating into our surplus to fund the second server, but will soon have a monthly shortfall so please join the community if you enjoy using the site and can afford to do so . Cheers!

Dan and Scott

CAPE Colours & Chart Design Update

With Spring (apparently!) here, our attention starts turning to the convective charts. There are a few, but hopefully useful, updates here.

We have always been fairly happy with our CAPE charts but the low-end of the colour scale did not stand out enough and hence this has been changed to a more obvious grey palette leading into greens above 500 j/kg.

CAPE contours will be added to smaller regions on coarser models like GFS, ARPEGE, ICON (not NAM 3km, HRRR or AROME as this is computationally very expensive for now). Lifted Index contours will still be drawn where the data exists (again available only for smaller regions).

Finally, 500 hPa geopotential height has been added to the slightly larger regions as this is such an important variable for relating the instability to the large scale driving weather pattern.

Huge updates are on the way and our patrons are helping decide which new models go live first. Join the discussion and add your ideas here –> https://www.patreon.com/wxcharts

Stay tuned,
WXCHARTS

A Guide to the New Layout & Features

There has been a lot of work going into the layout of WXCHARTS lately and yesterday  we released some exciting new features. The main updates are as follows:

  •  Three new layout options
  •  New GIF button
  • Town and City place names

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Three New Layout Options

We are very excited to work with enthusiastic folk very kindly supporting us on Patreon.  A vote was cast and the  new layout options were most popular over other development areas. Users can now select different ways to view our weather charts.

There are now 3 options and the clickable icons are located above the model list on the left side of the screen. The icons are described below in more detail.

  • Option 1 – Original: The regular layout we have had in place since the inception of WXCHARTS. Variable and region selection on the left, chart in the middle with meteogram/skew-t on the right – nothing new here!

  • Option 2 – Large View: An enlarged version of option 1. The meteogram area slides away to allow for a much larger chart area. This is ideal for those using the website on smaller screens or for just getting a closer look at some interesting charts.

  • Option 3 – Panel of 4: Arguably the most exciting layout option. Users have a huge amount of control over how they want to view the weather. Users can build a panel of 4 charts with just about any combination from our increasingly vast collection of variables and models. However, there is some understanding required here to get the most out of this layout. The first thing you need to know is that the top-left panel is dominant when it comes to model changes and the time-steps that are displayed. It is essentially the controller.

We think it is pretty straightforward to understand – each panel can be clicked ready for selection and then a variable can be chosen to fill that panel. Once you have selected a desired model and variable in the top-left pane, try filling the other panels with variables from other models. A very useful tool for comparing models against each other. Just mucking around with the 4-panel view for a few minutes should make things clear as it is pretty intuitive.

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New GIF Button

The GIF button has been moved away from the chart area and is now living under the list of variables in the left panel of the screen. It is larger and is much cleaner to use.
Nothing too exciting but this should add to the user experience. We continue to look forward to users tagging @wxcharts in cool charts and GIF animations from our website.

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Town and City place names

We have created an overlay for all of our smaller maps so that users can show or hide town and city place names. The option can be found in the page settings at the very top-left of the screen.

This overlay is particularly useful on our zoomed maps. There is still some work ongoing to tidy up the towns and cities labelled. You may also notice star symbols on some of the maps. This is from patron users sponsoring us $5 a month choosing a favourite location to add to our maps. You can join them here.

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What’s Next?

We are about to fund a second server thanks to the support from our patrons. We will be working closely with them in prioritising items on our massive to-do list. Our plotting capacity will be increased and this will open the door for plenty exciting development including:

  • New models
  • New regions
  • New variables
  • More timely data

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Naturally, we look forward to hearing any feedback on the new features released today. We pass on the responsibility to you in making some great chart combinations on the 4-panel and we look forward to seeing them on social media. Let us know what your favourite chart combinations are.

You can like us on Facebook or follow us on Twitter.

Major Hurricane Irma – Forecast & Uncertainty

There is a lot of talk about hurricane Irma right now. Irma has been tracking across the Atlantic over the last few days with fluctuating intensity. Currently at category 3 (sustained winds of 115 mph at 0200 AST 4 Sep), Irma is officially a major hurricane. This blog post tackles some of the challenges in the forecast and there is no better place to gain an overview of the situation than the National Hurricane Centre’s (NHC) official 5 day forecast.

Hurricane watches have already been issued for parts of the Leeward Islands for later on Tuesday (tomorrow). Puerto Rico, Dominican Republic and the Bahamas are increasingly likely to see watches issued over the coming days. Already using the word ‘likely’ gives a hint at where this blog post is going. How likely is it that the above mentioned places will see impacts from Irma?

Starting with a forecast that gives us event probability, the realm of uncertainty can be tackled one step at a time. It is worth being aware that a hurricane does not need to track directly over a certain area to be problematic. A radius of damaging winds can extend hundreds of kilometres from the storm centre, this is why we developed tools to spatially identify where winds are likely to exceed various thresholds. One of the most useful thresholds is that of tropical storm strength (34 kt sustained wind). The following flow of images looks at Irma at 24 hour intervals over the next 5 days.

This distribution of probability leads us to the all important topic of likelihood and uncertainty. Communicating uncertainty is one of the biggest challenges a weather forecaster will face. The track, timing and intensity of a hurricane (like Irma) are all governed by processes within a chaotic yet vastly connected atmosphere – there are bound to be countless challenges. Ultimately, we want to know where Irma is going to go. The timing and track uncertainty go hand in hand – crucial timing of large scale processes can have large impacts on Irma’s path and speed. There are two main upper-level driving features that we are going to cover here, a trough over the eastern USA and the broad high over the North Atlantic.

Previous forecasts have suggested that Irma would take a more northerly track, brushing the Bahamas before curving along the Eastern Seaboard stirring some interesting conversations on social media. However, more recent guidance suggests that the ridge keeps a nose over the Sargasso Sea so that Irma is partially blocked from following a safe path into the North Atlantic. But what of the trough? Usually a pronounced upper feature such a trough would help push Irma away from a US landfall. Unfortunately, the fate of the trough is rather complicated. By the time Irma reaches the vicinity of the Bahamas, the trough may have become cut-off from the main flow under an anticyclonic wave break. Essentially a cut-off feature holds more uncertainty than a typical trough pattern. Competition in the dominant steering flow gives a number of outcomes. Take an ensemble of storm tracks for example:

A number of scenarios can be displayed in a single GEFS run and Irma’s tracks do that to a certain extent. The difference between each ensemble member comes down to how far west the storm centre reaches before the curve north begins. This partially falls down to the fate and timing uncertainty associated with large scale drivers like the aforementioned trough. The last (but certainly not least) uncertainty yet to be discussed is intensity.

Going back to the point about track and timing uncertainty going hand in hand… If the track governs the environment in which Irma will move through, then the intensity is hugely dependent on the track itself – a conditional uncertainty if you will. Uncoupled models like the GFS regularly resolve Irma to bottom out a central pressure well below 900 hPa. It is very likely running away with an over intensification but we can learn that the environment in which Irma is likely to move through has very little impeding characteristics (like shear, cooler sea surface temperatures or significant land) and this holds healthy for hurricane intensification along the forecast track.

It is best not to dwell on individual forecast runs for intensity (or track for that matter) so attempting to identify a trend in a forecast model can help put a single forecast run into context.

All images in this panel are valid for the same time taken from 4 different GFS forecast runs. Reading the images from top left to image to bottom right (oldest to latest forecast), notice that Irma is resolved consistently as a powerful hurricane and trends to the southwest. This is of great concern and has also been reflected in the ECMWF model. To compare the ECMWF to the GFS, the latest forecasts are impressively similar out at 1 week, spot the difference.

Clearly a lot to take in. To summarise the uncertainty of Irma is no easy task but hopefully this short blog post ties together a few concepts that underly the complicated forecast.

Best and latest information on official advisories, watches and warnings concerning Irma can always be found at the NHC’s website.

A wide range of models and forecasting tools can be found on our page: wxcharts.eu

Frequent updates on Twitter and Facebook.

Europe – Heat Retreats

A Brief Look Ahead

The weather across Europe has seen a major split lately with a quick glance at the jetstream revealing the unusual setup. A southerly tracking jet meanders its way over the British Isles and into the Iberian Peninsula before heading northeast through the continent towards Scandinavia.

A meandering jetstream.

It comes as no surprise that low-level temperature gradients show an extreme west-east split. From a more in-depth perspective, a low-level temperature gradient helps drive the energetic nature of the jetstream.

A huge split in temperature anomalies. Cold air pours into the west whilst tremendous heat affects the east.

It is indeed cooler in the west and warmer in the east but what’s next? Perhaps a good place to start is to look at the synoptic setup by considering the 500 hPa geopotential height anomaly. A developing upper-level low is they key player in the broad weather pattern in the days to come across Europe. Latest guidance from the ECMWF is summarised below with the upper-low gradually sliding from west to east. The low becomes well and truly cut-off by the weekend.

The progression of the low is quite slow but one of the most noticeable changes for Europe will be that the colder air will steadily move east, easing the heat for many during the weekend. However, an upper-level weather pattern of this nature introduces many ingredients that hold favourable for severe weather. Downstream of the upper level-low, there is significant instability under substantial wind shear.

Convective Available Potential Energy (CAPE) from the GFS and Bulk Shear from the Arpege.

The supercell composite combines the instability, shear and storm-relative helicity model outputs of the GFS in an intuitive way to help highlight areas susceptible to severe weather. This is how it looks over the next couple of days:

Supercell Composite.

The large-scale pattern and its progression holds interesting days ahead for European weather. It is certainly worth following forecasts and events over the coming days as the upper-level low slides east. A wide range of models and forecasting tools can be found on our page: wxcharts.eu

Frequent updates on Twitter and Facebook.

Welcome to the wxcharts blog!

This is the first of hopefully many blog posts on this new addition to the http://wxcharts.eu site. It’s still a work in progress as you can see, but we hope to add many new posts over the coming weeks and months.

Posts will be a mix of in-depth current weather discussion, forecasting advice, information about new features and help on how to get the most out of the site.

Stay tuned…..