No icing forecast - good to go (yeah, really?)

The TAF forecasters probably take this data (lifted index and CAPE) in consideration. There where there is no TAF data available, you will have to resort to other sources than TAF. If you want to see a trend for a specific area in Europe a few days ahead and how it evolves, it is best to have access to this data yourself, isn't it? Isn't it true that to make a good judgement of the weather for your flight, you combine the data from several sources and make then your own judgement?

Achim,

The German Weather Service (DWD) offers icing forecasts. This is what pilots consider to be the "icing forecast". Other sites have similar charts. The algorithm is very pessimistic, you better do your flying in MS Flight Sim if you make your decisions based on this forecast.

I hope you have made your asessment of the Advice product known to the DWD. I don't know what your experience with this product is, but I can tell you that from my experience in the last 12 years working at a weather service, I found Advice mostly very accurate as to the positions of the areas where one should expect ice, yet as you say slightly pessimistic on the intensity side.

Yet, I'd say if you keep out of the areas Advice sais have ice altogether, you are not likely to find any. If an area is painted in any colour and you fly a non-fiki airplane, stay away. If its red or yellow, stay away in anything without active anti icing.

If people here are talking of CAPE and other convection products, sure they give a pretty good indication about the possibility of convectice activity. And where there is convective activity, icing is very possible. However, that does not mean, if the convection indexes are in the green then there is no ice.

Pireps: They do exist, they are frequent but they are basically used in a different way. If you report icing or turbulence or whatever weather related report, your PIREP will be forwarded by phone to the aviation weather department, who then decide whether to issue an Airmet or Sigmet. Most of the PIREPs given in Europe end up in that form. If you see an Airmet or Sigmet which sais "observed" rather than "forecast" that means it is based on or verified by pireps. (You may see an early Airmet issued with a FCST in it which is then replaced by OBS once we have reports).

Other than that, the truth is that icing has to be expected anywhere where there is visible moisture and temps in the icing range. There are a lot of products which can show this, but personally I don't think there is any which currently matches Advice by DWD. There used to be a good one from the Sembach site too, but that one is gone unfortunately.

For practical purposes, IFR with non FIKI airplanes should happen either in VMC or if there is IMC then below freezing level. That is probably the safest icing forecast and it's pretty easy to determine. Yet, Advice gives you pretty much this combination of factors in a nice graphical format.

And btw, Achim... MSFS can't do icing, so it is pretty pointless for anyone using it to use Advice :) You have to use X-plane for that.

Peter and Aeroplus:

The people who do TAF's of course have access to all this and then some. And of course they use it, as well as a lot of other things too. Not least, they have a LOT of experience for the area they forecast, so they can see things which people who know the theory but don't work on the practical side every day simply can't see.

LFLL 200500Z 2006/2112 VRB02KT CAVOK PROB40 TEMPO 2013/2017 FEW065CB PROB30 TEMPO 2017/2021 -TSRA SCT060CB

I had a quick look what happened that day. There was some convective activity in the area of Lyon and north of it at around 17z and later plus southeast of Lyon as well as in the Rhone valley but by the looks of it not at Lyon itself. So the TAF was pretty much spot on.

Lyon and the area around it is a pretty horrific thunderstorm alley. Several of the heaviest hail damage events I know of happened in that area. (I just remember Air Inter, Air Transat and Easy Jet as a few, but there were more.) For that reason, if there is any good reason to assume that there will be convection, stay away from Lyon and go west of it. The guys in Toulouse who do the Lyon Forecasts of course know this and are pretty sharp when forecasting that area.

On the subject of what non meteorology specialists can take out of all these charts, my feelings are a bit ambivalent. While I personally love the many great weather charts available to us today (If I remember what was available when I started flying, progress has been mindboggling at times) but it should be remembered that charts and models need to be interpreted to be of any real use. I withness this on a regular basis and there are people who can really read these models with a very high degree of accuracy because they know their strenghts and weaknesses. This is something the general public and also pilots can not really know unless they spend a LOT of time studying the models and draw their own conclusions. So when it comes to unleashing a wealth of complex information such as cape indexes e.t.c. to the general population and pilots in particular, I am wary of the implications. Personally I believe this is quite difficult for people who are outside the actual profession to make real good use of them. Yes, these products give a pretty good indication of what is to come, but why not call up a forecaster on the phone and get his take? We still get a lot of folk who do and normally these are the more experienced guys who know what they don't know,all material nonwithstanding, and their experience tells them that getting a brief by an experienced aviation weather forcaster is pretty hard to beat. Not because they are sooo much cleverer than yourselfs, but because it's their job to know the models inside out plus they have their experience of day by day weather analysis and prediction.

Urs,

Not least, they have a LOT of experience for the area they forecast

can you tell me why the guys doing the LSZH TAFs every now and then completely mess up their forecast? About 3 weeks ago during the passage of a front, both GFS as well as the DWD (EDNY TAF) correctly predicted the cloud base to drop from ~6500' down to ~1000' at around noon, in the case of GFS even days in advance. Yet it took the LSZH TAF until about 10o'clock to "predict" that drop too.

But what worries me even more is that they sometimes get the METAR's wrong too. How you can classify a solid cloud layer extending over thousands of square miles with no vertical movement as "BKN" is beyond me, and I found the explanations by Daniel Buck quite weak.

getting a brief by an experienced aviation weather forcaster is pretty hard to beat

That hasn't been my experience. We used to call the briefing hotline of Meteoschweiz whenever we were unsure about the weather. We either got confirmation that the weather development was uncertain, or got outright wrong advice. One day we called and asked about the possibility of fog the next morning, the meteorologist was very sure that there was no possibility of fog development, yet we ended up with the Mittelland covered in the thickest fog I've ever seen which lasted for almost a week.

So we've given up calling the expensive hotline, because it never added anything we didn't already know from studying the weather ourselves.

Yes, these products give a pretty good indication of what is to come, but why not call up a forecaster on the phone and get his take?

The DWD has a 24h phone service for met briefing and I've used it at times. What most people don't know is that there is a non premium rate number which you are allowed to call when abroad (because premium service doesn't work). There are ways to be "abroad" when calling a phone number but I would not do that...

In my experience that service is not very useful. The people are usually very competent (real meteorologists after all) but it's 90% CYA (cover your a..). Unless it's CAVOK, they have a strong urge to recommend you to not fly which I think is useless. If the weather was great, I wouldn't be calling. Of course it's my judgement but I'd prefer a different attitude -- "how can we make this work" instead of "is there the slightest chance of this this flight not being risk free".

The one thing I got out of them is competent estimates about front speeds and direction changes. Fronts tend to change their velocity and direction and can arrive hours earlier or later than predicted. This is crucial information and not that easy to get from the available sources. The DWD forecasters have very good data about this whereas I would have to look at sat or strike data and compare them and estimate the travel speed.

So when it comes to unleashing a wealth of complex information such as cape indexes e.t.c. to the general population and pilots in particular, I am wary of the implications. Personally I believe this is quite difficult for people who are outside the actual profession to make real good use of them

Oh well, that is a great example of professional conceit. For IFR GA pilots, there is nothing more important than understanding weather. Many GA pilots have a very limited interest/understanding and end up spending their career with pattern flying / € 100 hamburgers and the odd mid distance trip when there is a week long HPA (like right now). With what is available today in literature and weather data, a hobbyist can get very far in understanding the weather and drawing conclusions.

But what worries me even more is that they sometimes get the METAR's wrong too. How you can classify a solid cloud layer extending over thousands of square miles with no vertical movement as "BKN" is beyond me

I had a case of this and pursued it with DWD. When I came back from Croatia to Stuttgart, I was "lured" by the METAR which gave me something like FEW007, SCT015, BKN025. Clearly doable (I needed to transition to VFR). Well once I arrived I could not find a damn hole in this BKN025 layer which started at ca. 6000ft so I went directly overhead the airport of Stuttgart (where that METAR originated) and it was a ca. 5000ft thick solid OVC layer with highly probable icing. Tower and other crews confirmed it was OVC.

Given that I really didn't want to end up in EDDS and my other cloudbreaking alternate with ILS EDTY reported BKN004 (not good for changing to VFR) and most importantly my microlight qualified co-pilot was generally in awe of everything that looked like a cloud, I chose an alternate very far away. I was very mad at DWD so I started pursuing this.

The next day, I tracked down the person that issued the METAR and TAF at that time and he remembered the situation. He told me that this BKN025 layer was there but there was something above it (this damn thick OVC layer) but BKN is not enough to "look through" which means they cannot determine the layer above so they cannot report it. Bummer! He was following the procedure but the METAR was a useless piece of ... for a GA pilot. They get away with this because the airliners don't care about anything but the cloudbase for their approach.

The Sembach ICING RISK forecasts were based on the GFS model. I do not know their formula for it, but it should be a combination of: (a) where is the freezing level, (b) are the clouds of the convective type and (c) how much moisture is in the air and maybe some more.

The issue is that ice can appear anywhere in clouds below zero temps and we are reluctant to make a dynamic chart showing the icing risks based on the above assumptions. We would be afraid people would rely too much on this when flying. The Lifted Index and CAPE values by themselves only give information on the potential convective energy in the clouds, not about the risk of ice. You now need to combine the information with other data to make a good judgement.

I personally don't call weather forecasters anymore. They just don't give me the correct data and just cover their a... and stay on the very, very conservative side.

If we would be able to come up with some criteria for icing risks like above, I could consider making a dynamic chart that shows the potential icing risk areas with some disclaimer that this is no guarantee for finding no ice in other areas. Would would we have to include in the formula?

The SIGMETs do give valid and good information about potential hazards like freezing rain and severe icing and they show in our app already.

For the thunderstorm risks we also include the "European Storm Prediction" chart, which gives you a good indication of where you can expect thunderstorm activity in Europe.

this BKN025 layer was there but there was something above it

In my case, there was nothing above it except for some cirrus, and the base was correct, it was just nowhere near broken...