59 minutes ago, blingthinger said:

The gribs in this case are from forecast simulations: a CFD run. Mid level cloud coverage (any cloud coverage for that matter) is an output because it's a 3D domain.

Cloud gribs consist of multiple layers including bases tops in column format + coverage

XP converts them into volumes that it then applies things like wind to and uses updated grib data to manipulate how it changes.

gribs themselves are the raw data from the NOAA, they are now mirrored from the LR servers (because the NOAA servers are unreliable), all the CFD stuff is done by XP locally.

Edited January 20, 20251 yr by mSparks

11 minutes ago, mSparks said:

gribs themselves are the raw data from the NOAA

Yes, exactly. Raw "data" from their CFD predictions (it's not really "data" in a measured sense, obviously. It's prediction results). There is no magical system that gathers temperature/pressure/clouds/winds, etc. for the entire globe and averages it into one nicely-smoothed domain in full 3D (which is precisely what the gribs contain) including over oceans. What's more is that even if such a magical measurement-blending system did exist, NOAA would not be sending it out with time stamps in the future which is exactly what does happen now. XP is pulling down gribs that happen to have been generated in 3hr intervals by the NOAA CFD model. Forecast, not current status.

The only tool that humans are currently in possession of that can forecast the full globe in full 3D, is CFD. And a few fancy new ai/ml models but that's a different story. 

The image you've shown is after XP has blended in the METARs.

And no, XP is not doing "CFD stuff" locally. It's simply a blending algorithm. NOAA does the CFD for us.

9 hours ago, Franz007 said:

This has not been my experience at all. And it is the thing I am always looking very closely to and I have been amazed about how close it is to what is being reported by the metar. It can happen in some rate occasions that a reported overcast-layer is depicted as broken but most of the time because it was in transition in real as well. A metar is already outdated after it has been published. In real you won’t get the exact same conditions as the metar during the whole 30- or 60min cycle. Often we see transitions from overcast to broken. If you see some situations where it doesn’t match at all, you absolutely should report it. But it is for sure not true in general.

It doesn’t happen just « sometimes » but always because that’s the way XP11 draw its clouds. They are just static and will delete everything and redraw the new situation, meaning it will go from full of clouds to scattered within 2 seconds. I cannot think of a worst way; it’s completely immersion-breaking and highly unrealistic. In XP12 the clouds are dynamic. But well, if you prefer the XP-clouds in XP11 it’s your opinion but I think you are part of a very small minority, because the weather in XP12 is probably the thing that has improved the most compared to XP11.

I've reported the cloud bases bug a number of times over the past two years.

The sim should draw close to what the METAR reports. 

Glad I'm in the minority. 

8 hours ago, mSparks said:

with the exception of the night clouds bug, really not seen this

around 1000 feet I believe it switches from cloud coverage to visibility (because the clouds do no accurately capture the vis, and vis is the important number for landing)

I snapped this at the "relief" of seeing the runway lights just breaking out of the clouds

for the prior 1000 feet descent before that there were just "hints" at the tops of buildings

We've talked a lot about scud running before

having solid vis done properly has always been a strong point of X-Plane - and that hasn't changed.

 

What was the ceiling on the METAR just before you broke out of the clouds?

Here is what I'm seeing just now XP 11 vs XP 12...

@ KSNS the reported ceiling as of 1400Z is 200 overcast 4 miles visibility.

In XP 11 as soon as I hit 200 feet AGL I was in the clouds and cannot see the ground. 

In XP 12 around the same time @ 200 feet .. i didn't even enter the clouds and can still see the ground 

Edited January 20, 20251 yr by drix9

23 minutes ago, blingthinger said:

There is no magical system that gathers temperature/pressure/clouds/winds, etc. for the entire globe and averages it into one nicely-smoothed domain in full 3D (which is precisely what the gribs contain)

https://www.opendap.org/

It's all done by satellite, e.g.

https://www.star.nesdis.noaa.gov/goes/sector.php?sat=G16&sector=smv

and provided as gribs

9 minutes ago, drix9 said:

@ KSNS the reported ceiling as of 1400Z is 200 overcast 4 miles visibility.

KSNS 201533Z 15007KT 3SM BR OVC003 04/04 A3021 RMK AO2 T00390039

XP12 has a cloud base at exactly 300 feet

with above that fully OVC

Sooo, something else is going on.

9 minutes ago, drix9 said:

This is night time, I already linked you a detailed description from someone else as to how clouds are breaking after sunset.

Edited January 20, 20251 yr by mSparks

44 minutes ago, mSparks said:

and provided as gribs

Sure there's lots of gribs out there. Like you say, it's a data format. NOAA uses it for various products.

You'll notice that the time stamps of those satellite images (not gribs...odd that you'd post a totally random and useless url...oh wait nevermind par for the course) in that NOAA link are in the very recent past, by a few minutes, and not 3 hrs in the future, like what appears in the Output/real weather folder. XP's using CFD-generated forecast gribs. Not satellite data of current status.

23 minutes ago, blingthinger said:

Sure there's lots of gribs out there. Like you say, it's a data format. NOAA uses it for various products.

You'll notice that the time stamps of those satellite images (not gribs...odd that you'd post a totally random and useless url...oh wait nevermind par for the course) in that NOAA link are in the very recent past, by a few minutes, and not 3 hrs in the future, like what appears in the Output/real weather folder. XP's using CFD-generated forecast gribs. Not satellite data of current status.

https://forums.x-plane.org/index.php?/forums/topic/282159-what-the-heck-is-a-grib-file/

GFS data looks like it is here

https://www.nco.ncep.noaa.gov/pmb/products/gfs/

Edited January 20, 20251 yr by mSparks

27 minutes ago, mSparks said:

GFS data looks like it is here

Yep.

https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs.php

"The forecast component uses the Finite Volume Cubed (FV3) model...."

Finite volume is a specific discretization method of the Navier Stokes equations. Also note the text in the url itself. GFS = CFD. 

"The Global Data Assimilation System (GDAS), which run a 4D hybrid ensemble-variational data assimilation scheme, produces initial conditions for the GFS forecast."

GDAS is the semi-magical system that does an aggregate of all the weather measurements that are used as the initial and boundary conditions for the CFD run.

 

5 minutes ago, blingthinger said:

Yep.

https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs.php

"The forecast component uses the Finite Volume Cubed (FV3) model...."

Finite volume is a specific discretization method of the Navier Stokes equations. Also note the text in the url itself. GFS = CFD. 

"The Global Data Assimilation System (GDAS), which run a 4D hybrid ensemble-variational data assimilation scheme, produces initial conditions for the GFS forecast."

GDAS is the semi-magical system that does an aggregate of all the weather measurements that are used as the initial and boundary conditions for the CFD run.

 

And I was replying to you saying

2 hours ago, blingthinger said:

There is no magical system that gathers temperature/pressure/clouds/winds, etc. for the entire globe and averages it into one nicely-smoothed domain in full 3D

->There is several, e.g. GDAS, its all done via satellite and everything, from the raw data, to multiple model outputs is provided as grib.

e.g.

https://eur-registry.swim.aero/services/met-office-3d-radar-service-grib2-100

24 minutes ago, mSparks said:

There is several, e.g. GDAS, its all done via satellite and everything, from the raw data, to multiple model outputs is provided as grib.

Yep, sure sure.

XP uses CFD results for its weather. Not satellite or measured atmospheric data (aside from METAR)

Edited January 20, 20251 yr by blingthinger

36 minutes ago, blingthinger said:

Yep, sure sure.

XP uses CFD results for its weather. Not satellite or measured atmospheric data (aside from METAR)

It probably sources (most) of the gribs from GFS.

This is forecasted atmospheric data, in the same way TAF data - terminal area forecasts are forecasted atmospheric data, the weather engine takes many sources (most of which only come in resolutions spanning a very wide area) and uses them to construct the local weather with ~foot accuracy. (like literally, I've had it rain on my house minutes after it rained on my house in the sim more times than count as coincidence)....

I have no idea what if anything you are agreeing or disagreeing with.. its all "models" and estimates, even when they send up weather balloons for GDAS, they don't fill the entire stratosphere with weather balloons, LRs data sources take point measurements, then estimate what was in between the measurements and how that is expected to change.......

That includes, for example

https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs/implementations.php

Quote

Assimilate additional COSMIC-2 GNSS-RO data (COSMIC-2 E1 and E2)

https://en.wikipedia.org/wiki/COSMIC-2

which looks a lot like satellites to me?

what exactly do you mean by

37 minutes ago, blingthinger said:

Not satellite

 

Edited January 20, 20251 yr by mSparks

26 minutes ago, mSparks said:

what exactly do you mean by

You know of satellites that have cameras/antennae that can see 3 hrs into the future? I'm sure the FAA would love to know about them.

1 minute ago, blingthinger said:

You know of satellites that have cameras/antennae that can see 3 hrs into the future? I'm sure the FAA would love to know about them.

yes? that's the point of them?

Same way a robots camera can see seconds into the future

How do you think they catch the ball without knowing where it will be in the future?

GFS uses a Local Ensemble Kalman Filter plus the Stochastic Kinetic Energy Backscatter from GDAS, then feeds that into a model (probably a linear regression) to forecast how it will develop.

X-Plane slurps all this data and uses it to create an estimate of the weather now, and an estimate of the weather 1 minute from now.

see also

 

33 minutes ago, mSparks said:

Same way a robots camera can see seconds into the future

Booo!!! Sub par. You're not your normal self today. 

 

43 minutes ago, mSparks said:

GFS uses a Local Ensemble Kalman Filter plus the Stochastic Kinetic Energy Backscatter from GDAS, then feeds that into a model (probably a linear regression) to forecast how it will develop.

tsk tsk tsk. No references for these claims?

 

36 minutes ago, mSparks said:

linear regression

This is what XP is doing internally, yup.

5 hours ago, drix9 said:

The sim should draw close to what the METAR reports. 

That‘s what it does.

8 hours ago, blingthinger said:

tsk tsk tsk. No references for these claims?

 

10 hours ago, mSparks said:

https://www.emc.ncep.noaa.gov/emc/pages/numerical_forecast_systems/gfs/implementations.php

Turn on Stochastic Kinetic Energy Backscatter (SKEB) scheme in GDAS ensemble forecasts

Use a Local Ensemble Kalman Filter (LETKF) with model space localization and linearized observation operator to replace the Ensemble Square Root Filter (EnSRF)