Icing forecast products

[masloki]

So, looking at Wisconsin weather today, I see the clouds forecast shows icing NW and NE. (Valid 18z)


But looking at icing probability shows trace on the southern border and pretty much nothing NW and NE. (Valid 16z)


Icing severity at 5000, looks something awful. (Valid 16z).



So, what gives? Which one do you put more weight on in the non-fiki, SE piston, planning world?

 

[midwestpa24]

So, looking at Wisconsin weather today, I see the clouds forecast shows icing NW and NE. (Valid 18z)
View attachment 103254

But looking at icing probability shows trace on the southern border and pretty much nothing NW and NE. (Valid 16z)
View attachment 103255

Icing severity at 5000, looks something awful. (Valid 16z).
View attachment 103256


So, what gives? Which one do you put more weight on in the non-fiki, SE piston, planning world?

I'd take it all into account. I'd also look at the Skew-T for temperatures aloft and cloud layers. If there is any question about ice, I wouldn't go looking in a non-FIKI airplane. You also need to factor in the bases, can you get underneath them legally if you need an out. But I'm pretty conservative when it comes to ice. Ice only belongs in my drink.

 

[kaiser]

I think the top screen ties more to Airmets than FIP/CIP.

For icing specifically, I probably give the bottom two more weight. I use the top more strategically and planning escape routes.
+1 for adding Skew-T to the planning tools.

In a piston single non-fiki, I’m flying VFR below those clouds, or VFR on the ground in my car. I’d need a minimum light (I.e. loaded well below max gross) fiki turbo piston twin or turbine to punch through that (if I really needed to be anywhere). And around Chicago, I’d probably depart VFR and pick up my clearance later in order to avoid being kept in that layer any more than I needed to.

 

[masloki]

Any good skew-t flight path and altitude options out there? I am using rucsoundings.noaa and it leaves a bit to be desired for flight planning.

 

[Country Flier]

As @kaiser said top only shows airmets. In addition to Skew-T, I also like the temp aloft forecasts added to all that you are looking at. I flew in northern Michigan, in the soup at 5000, just the other day in a Mooney without FIKI. It can be done in winter, but give yourself outs and don't cut things close.

 

[Clip4]

How about a simple look at the low level prog and Graphical Airmet. Freezing level at the surface, IFR in southern WI, marginal VFR central WI, Airmet for ice 90% of Wisconsin.

 

[Jim K]

Airmets are essentially worthless in my opinion.

I really like the map on 1800wxbrief.com You can adjust for altitude and set it to display the forecast confidence to your own risk tolerance level. Here an image I just took showing severity <50% likelihood, as well as any SLD chance, at 4000':


That and pireps would be my primary sources. I use the rucsoundings site as well, I'd love to hear if there's something better. I like the gfa tool on AWC to drill down on cloud heights.

 

[kaiser]

Any good skew-t flight path and altitude options out there? I am using rucsoundings.noaa and it leaves a bit to be desired for flight planning.

I use an app called SkewTLogPro. It’s a couple bucks for Apple devices (don’t know about others). It’s still basic but you can put in a starting and ending airports, planned departure time, time en route, and define how many miles between each sounding. It’ll provide you with a quick set of those soundings, but only in a straight line.

 

[TommyG]

Also why I wish there were more pireps on cloud tops. Kind of a no brainer to find the bases through metar along the route. Knowing tops is always nice, that way we know or can plan to be above the could and not in it the entire way. Pick up icing you know can get up another 2k feet and be out of it.

 

[Country Flier]

Also why I wish there were more pireps on cloud tops. Kind of a no brainer to find the bases through metar along the route. Knowing tops is always nice, that way we know or can plan to be above the could and not in it the entire way. Pick up icing you know can get up another 2k feet and be out of it.

Every time I fly IFR, I try to give a pirep...yet rarely do I later see it. Maybe I'm not doing it right...?

 

[Jim K]

Every time I fly IFR, I try to give a pirep...yet rarely do I later see it. Maybe I'm not doing it right...?

I can't figure out why some make it in and some don't. I've been sitting in my hangar and heard a jet give a pirep on my handheld that never shows up in the system.
From the 7110 :

1. Solicit PIREPs when requested, deemed necessary or any of the following conditions exists or is forecast for your area of jurisdiction:

1. Ceilings at or below 5,000 feet. These PIREPs must include cloud bases, tops and cloud coverage when available. Additionally, when providing approach control services, ensure that at least one descent/climb–out PIREP and other related phenomena is obtained each hour.
2. Visibility (surface or aloft) at or less than 5 miles.
3. Thunderstorms and related phenomena.
4. Turbulence of moderate degree or greater.
5. Icing of light degree or greater
6. .....

So they're supposed to collect them, and I'm pretty confident they do, but they don't seem to get passed to FSS for dissemination.

 

[NealRomeoGolf]

I've been using this more to predict freezing levels.

https://weather.us/model-charts/euro/usa/freezing-level-feet.html

 

[NealRomeoGolf]

I can't figure out why some make it in and some don't. I've been sitting in my hangar and heard a jet give a pirep on my handheld that never shows up in the system.
From the 7110 :

1. Solicit PIREPs when requested, deemed necessary or any of the following conditions exists or is forecast for your area of jurisdiction:

1. Ceilings at or below 5,000 feet. These PIREPs must include cloud bases, tops and cloud coverage when available. Additionally, when providing approach control services, ensure that at least one descent/climb–out PIREP and other related phenomena is obtained each hour.
2. Visibility (surface or aloft) at or less than 5 miles.
3. Thunderstorms and related phenomena.
4. Turbulence of moderate degree or greater.
5. Icing of light degree or greater
6. .....

So they're supposed to collect them, and I'm pretty confident they do, but they don't seem to get passed to FSS for dissemination.

I think the ones I give just get used locally. I gave my report on Monday to approach and heard them use it later to another GA piston. Don't think it ever got into the pirep system though.

 

[masloki]

Well, I did some more digging while not flying to my NYE party. The airmet is issued only for moderate or worse icing at greater than 3000 sq. miles. You might get a CWA for smaller or lesser. Ah, good details to keep in mind there.

 

[coma24]

I skimmed through the images, skimmed the text and thought to myself, "I bet this is Scott." Checked the author, smiled...then read the post in full. Your work is always second to none, Scott!

 

[coma24]

Also why I wish there were more pireps on cloud tops. Kind of a no brainer to find the bases through metar along the route. Knowing tops is always nice, that way we know or can plan to be above the could and not in it the entire way. Pick up icing you know can get up another 2k feet and be out of it.

SkewT charts are very helpful for top prediction, if you're not already aware.

 

[coma24]

Every time I fly IFR, I try to give a pirep...yet rarely do I later see it. Maybe I'm not doing it right...?

If you just casually report the tops, it's not going to make it into a PIREP, ever, that I'm aware of. If you have an urgent PIREP, ATC will get that in the system in a hurry. Otherwise, short of that, be sure to tell ATC that you'd like to file a PIREP, then go from there. Boldmethod and AOPA have videos on efficient ways to file, if it helps. In short, other than urgent PIREPs, I don't think controllers are going to take a casual tops report and dutifully forward it as a PIREP to Flight Service.

 

[masloki]

Such a high pressure created subsidence or sinking air and that tends to create a subsidence inversion aloft which caps the lower part of the atmosphere

Thanks for digging in to the history - it really helps me parse the different icing products better. So the forecast was fairly stable a few days out. When I was looking at it, I was thinking, "sweet, some nice highs, clear skies, nice flight for New Years eve." How typical is it for this scenario where the high has an inversion that caps in enough moisture to keep a cloud deck like this? Because from the my lightly trained eyes, a few days later the Sunday pressures and fronts looked much the same but had clear skies after noon.

 

[FlyingMonkey]

I usually hop on Com2 with Flight Service and give a Pirep while monitoring Com1. It is so fun to watch it appear shortly on the EFB through ADSB as a graphic Pirep. Every time I have done it through Flight Service it has showed up in flight on the EFB. Try it!