Pictures are better than words, so I created this table to try to show what I said in my previous reply, hope it helps.
Latest posts made by nwindy
RE: Moon phase incorrect
Yes, screenshot is below. I now noticed that the moon graphic is composed of a blue shape. And this blue shape is used in both locations. However, in the Meteogram, the shape is on top of a white background, and on the Home info, is displayed on a dark background. When on the white background, it appears to be the correct phase [1/4 moon], but on the dark background, the blue shape [since it's lighter than the background] gives the appearance of the incorrect phase.
A solution may be to give the graphic in the Home tab a white background, but I would not recommend this since it would make it difficult to distinguish between full moons and new moons. I.e. the full moon graphic I believe is an empty blue ring, so when on a white background, there's a white full moon. And the new moon is a filled in blue circle, so on the white background it appears 'dark,' like the new moon. However, both displayed on a dark background would be confusing as both appear a full circle that's light in color, indicating a full moon. I also attached a graphic of the moon phases.
Moon phase incorrect
Recently updated to 37.2.5.
Home Screen shows temp, wind speed, heading, and now moon phase. However, it’s the wrong phase. Today it’s showing a 3/4 moon (moon lit from the left), but the current phase is 1/4 (lit from the right). They’re both “half lit” but the light is just from the wrong side for the current date.
Note that the phase is shown correctly when the data is shown in detail when Basic or Meteogram is selected - moon phase picture shows up directly below the temperatures. At this time it is showing the 1/4 moon in those fields.
RE: Rain Value Meaning In Meteogram?
So, Windy takes the model data (once for each of ECMWF, GFS, NAM, etc.), runs it through deterministic models, and that spits out windy's 'layers,' generated on a 'high' resolution grid. And the results are not probabilities, they are straight up predictions for what's going to happen at that geo-temporal point. Correct me if that's wrong.
With the ensemble method; because it uses 20-21 forecasts for a larger area (lower resolution grid), with each input perturbed, and some of those numerus forecasts result in rain and some result in less rain, that is how that method generates a probability?
Is the reason you can't do this at a higher resolution just a computational limitation, or are the 20-21 points representative of sub-pixels in different geo-areas of one of the larger main output pixels (and so with more sub-pixels, the result is more accurate but at the same time covers a larger resulting land area)?
Rain Value Meaning In Meteogram?
I had someone ask me (while I was looking at my weather app, Windy) what's the percent chance for rain today? And, didn't have an excellent answer, just that it is predicted to rain X in. between the 1 and 4 o'clock hours.
Led me to doing some reading... came up a little short with specifics in Windy... So...
Short version: In the meteogram, what do the rainfall values mean in regards to probabilities/confidence and area (if at all)?
Starting with what I know:
- The values are for every three hours (not premium).
- When I move the pin/location indicator on the map, the data in the meteogram changes, even for the smallest movements.
- The values are absolute amounts (0.2 in, 4 mm, etc.)
- In meteorology there is a concept of Probability of Precipitation (PoP) which is calculated for a point, but sometimes also for an area. From this weather channel's post:
'' PoP = C x A where "C" = the confidence that precipitation will occur somewhere in the forecast area, and where "A" = the percent of the area that will receive measurable precipitation, if it occurs at all. ''
And this ^ is from the National Weather Service. Both C and A are themselves probabilities - values between 0 and 1 - so multiplying them together gives another value between 0 to 1. (Not what is displayed in the meteogram data)
- Is the ''location'' of the map in windy actually a point and the meteogram only shows the data for the weather happening at that point every three hours?
- Does the meteogram rain value imply a 100% chance of rain for the point-only location of the pin? Meaning there's no concept of area in that rainfall value (the A in the PoP formula) and that there's also no concept of confidence (C in the PoP formula) that actual rainfall will be the displayed rainfall value for that point?
- Is it true/common practice (as the link mentions) that rain amounts less than 0.01 in. are not included in the meteogram?
It seems that PoP provides a probability of rainfall over a rainfall threshold (0.01 in), with no indicator of how heavy the rain will be beyond that threshold. Whereas, Windy provides the heaviness/rainfall amount in absolute values, but only for a point. And if we want to communicate to other weather app users what the percent chance of rain is, our response should be: It's complicated, what is your app's definition of percent rain? And of corse, other apps don't say what the percentage actually means. Maybe windy could have an option to display meteogram values averaged over a user defined area... and then the values will change to %'s. Anyway...
Extra Radar Clutter?
This might not be a bug, but rather a technical limitation of the processed radar information.
I've recently noticed excess clutter around radar stations in the Northeast United States.
(I know clutter is expected and that it can be ignored - quite easily, but I've noticed more than normal lately.)
The normal amount that I see resembles the clutter in Kentucky, Indiana, Illinois, and West Virginia in the attached picture (Captured 15 Sep 2018).
I'm assuming that this is not due to a weather related phenomena, because if it is, then the other radar stations that overlap for continuity would show the excess clutter as well.
So, it appears that only specific radar stations in the New York/Canada area are affected/producing this excess clutter and that it is not due to weather.
NEXRAD on the Wonderground site has the option to Hide Clutter via a mathematical algorithm and it appears to work well.
If this is a computational error by Windy, could it please be resolved?
Or, if it's not an error and this type of thing is expected to happen to only a small selection of radar stations, then is it possible to add a feature to Windy to enable the hiding this clutter?
Possibly in a similar manner as the NEXRAD system?
Or, maybe the ability to select individual radar stations of interest and block others (if only one is known to cause trouble).
Or, another way is a feature that allows the user to pass (as in; high/low pass filter) a certain range of dBz levels on the radar map. This would be handy as the map does show 0 to 20 dBz in purple-blue-blue green, when light rain usually only starts at/above 20 dBz. Only showing >20dBz would hide the unwanted clutter.