Very nice summary Korina. Will be useful for a lot of users !
Best posts made by Yves70
As explained by @idefix37, there is no way for Windy to draw fronts. There are websites where fronts are drawn tha you can use.
Having said that, there are alternatives to visualise fronts that you can use with Windy. One way is to use the humidity map at 700 hPa. A front is materialised at this altitude with a humidity above 90%. Another way, combined with the humidity map is the temperature map at 850hPa. Ideally we should use the potential temperature (thêta’w) but still it can give you an idea of the temperatures differences between air massa so in fact discontinuity which is the sign of a front.
Again, those 2 maps don’t replace fronts map but it works quite well
RE: Rain Value Meaning In Meteogram?
Yes, the way the ensemble model calculates the probability is as you explain : for instance for the rain, each dot of the 21 dots can give a different level of rain (1mm, 4mm, 10mm,...). Based on that set of different levels of rain, the model can calculate several probabilistic values such as the average, variance,... This will allow you to quantify the risk of rain
Now, if the model has to adopt the same approach for many other parameters, such as pressure, temperature,... And for each parameter do the 21 calculations (do not forget that each calculation is the equivalent of a single deterministic calculation), computional limitation will be the issue if the model keeps the same grid. To overcome this problem, grid is bigger, calculation of the 21 dots for the different parameters becomes ok but accuracy will decrease.
Computational calculation is key. In average, weather forecast improves by one day every 10 years thanks to the computer (super calculator) progress
Mediterranean sea - Temperature
The temperature of the Mediterranean sea is quite high this year. In some ares, temperature at the surface is around 28°C. This is of course due to the hot spring and summer.
This situation is not without consequences :
a medicane was formed close to the Libyan coasts and hit last Friday Greece creating a lot of damages because of the wind and rain
yesterday, in the South of France, because (but not only !) of the intrusion of very warm and humid air from the sea, combined of course with other factors (instability, anomaly in altitude, wind shear), it created a multi cellular thunderstorm which was stationary : each new convective cell (this is why it is a multicellular system) is created in the exact opposite way of the move of the system in altitude because of the wind shear. This creates therefore a stationary thunderstorm which is terrible in terms of rain accumulation because you can get huge quantities of water at the same place during 24h or even more.
This thunderstorm created floating and a lot of damages in France (more than 600mm of rain in 24h)
Unfortunately, other episodes like the ones mentioned above could happen in the coming weeks,...
RE: Windy.com updates ECMWF model each 6h, with 1h detailed resolution
The model from ECMWF is called IFS. This model has 4 run per day: 0z, 6z, 12z and 18z. So far, Windy gave us access to only 2 run, 0z and 12z (the main run). Now, the Premium users have access to the other 2 run, 6z and 18z
RE: Rain forecast
First of all, please start to check the posts published on this forum and discussing rainfall forecast.
Example : https://community.windy.com/topic/13586/about-rain-calculate/2?_=1602329137551
There are many others, use the advanced search tool to fine them and to read them. You will find a lot of advices.
Principles are always the same :
- compare the different models to verify the consistency within the forecast from the different models. It is a kind of statistic approach to give you a level of confidence
- don’t look only the meteogram which is focus on one location. You should check with the Windy rain map, the rain forecast in an area of let’s say 20km around the location. Often, models foresees no rain at the location but for instance 5mm at only 10km from the location. Thereofore risk is high to get rain at the location.
Combining 1) and 2) should tell you the probability of getting rain or not
To complete what @idefix37 said, with the infrared, the colder the tp the higher the cloud is so potentially it could be a cumulonimbus type of cloud associated with thunderstorms but cirrus is also high and cold cloud and not associated at all with thunderstorms. As always in meteo, before taking a conclusion you should check other paramters, for instance check the visible channel as well to see if the cloud is thick or not. If not, what you are seeing with the infrared is probably a cirrus
RE: Displaying weather Fronts notations.
Fortunately for the meteorologists working for NOAA or other national institutes, their work and analysis cannot be always replaced by an application or a computer as it is the case for the front map for instance.
Having said that, there are couple of things you can do with Windy to try to see front, and air mass with different temperatures :
- check the humidity above 90% (very critical) and at 700hPa and 600hPa. You should see the fronts as illustrated :
The red zone shows the front, with humidity above 90% and just after, you can see a huge drop of the humidity with the brown zone
- check the temperature at 850hPa to follow air mass temperatures. Ideally, you should use the potential temperature (a temperature among others which doesn’t vary with the altitude) but this temperature is not available with Windy. Nevertheless, temperatures at 850hPa will allow you to compare different air mass and follow them, especially on the sea because hills and mountains could otherwise interfere at this level.
Same picture as above, same moment. You can see the temperature differences, as there is an air mass at 0°C followed by an air mass at 4°C. This confirms the front identified above with the humidity map and on top, you see that it is a warm front
This type of analysis will not replace a front map draws by professionals but at least you can get something thanks to Windy
RE: pluie venue trop tôt
Il est important de comparer les différents modèles : ICON, IFS (ECMWF), GFS,... C'est à cela que sert notamment l'outil de comparaison disponible avec le météogramme. Vous pouvez comparer les précipitations prévues par chaque modèle et vous forger une opinion sur la quantité de pluie probable.
Une autre chose à faire est de ne pas regarder uniquement le météogramme qui est focalisé juste sur votre localisation. Il faut regarder la carte des précipitations pour voir si autour de votre localisation, par exemple dans un rayon de 15km, il n'y a pas de la pluie prévue par les modèles. Si 5mm de pluie sont prévus à 5 ou 10km et rien chez vous, il faut se poser des questions quant à la probabilité que vous ayez tout de même de la pluie chez vous, le risque est grand car il suffit d’une petite déviation et vous avez les 5mm pluie aussi
Latest posts made by Yves70
RE: Code couleur
@Grégory-Bertrand Pour la Belgique, je suis essentiellement deux modèles : ECMWF et ICON/ICON D2. Le premier permet d’avoir une vue moyen terme assez fiable avec notamment les changements de régime et de températures. ICON / ICON D2 est très bon en cours terme pour la pluviométrie, quantités de précipitations
RE: Weather fronts
@gatorgrad74 there is no possibility to see the fronts but there are alternatives to see them : https://community.windy.com/topic/13381/fronts?_=1695647017813
RE: can I overlay rainfall layer on temperature layer?
@Keith-Cohen a possibility is to select the layer you wish, here rainfall, and combine it with the measured temperatures so observations
RE: why can't I fix a different wheather Model for my Region?
@Moby65 in the settings, choose to open Windy with the last layer opened. If you selected a specific model with this last layer, you will open Windy with this layer and the model you selected
RE: How many desktop devices can I use a Premium subscription on?
@chrismillard you can log on on all devices you wish to use
RE: Wind gusts
@shanekopcak first of all, wind gust is not wind speed. This is different. Secondly, when you check a parameter like the wind, you should always compare several models, and not rely on onky one. Now, are you using Windy app ? If yes, did you download the last version realesed recently for Android ?