Urgent PIREP for icing from M20P

[Scott Dennstaedt, PhD]

Urgent PIREP M20P
Time: Feb 8, 2020 1443Z
Flight level: 16
Icing intensity: Severe
Icing type: Rime
Urgent PIREP: MTO UUA /OV MTO010010/TM 1443/FL016/TP M20P/IC SEV RIM 1 1/2 INCH OF ICE/RM ZKCFDC/AF

1.5" of rime ice. Yikes!  And in the bases of the clouds no less (assuming the flight level reported is accurate).  A nasty case of stratocu.  This PIREP likely prompted the AWC to issue this SIGMET for severe ice.

The big picture tells the story!  This is the 12Z surface analysis below (PIREP was at 1443Z), but nice low-level lift right behind the frontal zone. 

 

Behind the front, very significant cold-air advection with high moisture content near the surface (dewpoints are high) gives rise to unstable conditions.  With warmer subfreezing air you can evaporate a lot of vapor into the air and that water vapor can condense out into drops (that are in this case supercooled). This relationship to temperature is exponential. In fact, you can see on the diagram below, with just a 10 degree difference (from 0°C to -10°C, the amount of vapor that can be evaporated into the atmosphere is nearly doubled!  That's why warm icing encounters can be the most dangerous.  

With snow cover on the ground in this area, the clouds are likely very clean giving rise to potentially larger drops.  

The Skew-T highlights the classic stratocu signature here.  Moist instability that is capped.  With the rather warm tops these clouds are guaranteed to be dominated by supercooled liquid water.

Also seen well on the GOES-derived cloud phase. Baby blue means the tops of the clouds are in the liquid state.

And that's also echoed in the IR satellite imagery with cloud top temps in that perfect icing range - yellow and pale greens indicate supercooled liquid water will dominate.

And if you were wondering, the Current Icing Product was showing a very high potential of icing at 2K.

With a moderate severity.

Edited February 8, 2020 by Scott Dennstaedt

[Scott Dennstaedt, PhD]

Here's the radiosonde launch out of the Lincoln forecast office.  Looks like the radiosonde sensor iced up pretty good shortly after the launch this morning.  

 

[aviatoreb]

Eeeh ghad - I pray that guy is safely on the ground now.

[exM20K]

Yowza! 

I elected to hop on the germ tube for a Chi->DFW three-day meet this past monday.  The PAX I was to pick up nearby had the flu, the weather mid-week looked challenging, and I *had* to be back Thursday.  That's an easy three strikes.

 

One of the biggest go/no go challenges I find is mid-range icing forecasts (2-3 days).  I wound up looking the soundings model forecasts on Windy.com.  I'd probably benefit from the live seminar in this area.  Will you be doing any live seminars again? Or is there one of the for-sale webinars on your site that would cover this?

-dan

[exM20K]

dupe.

Edited February 8, 2020 by exM20K

[kortopates]

Thanks for posting this with all the great supporting graphs! You are so right that the big picture is so important. But as pilots, METARs, TAFs, PIREPs are all well understood but the synopsis charts need much more understanding to be useful to many of us. Ditto for the very valuable Skew-t. But I think that one is pretty easy to learn the basics of.

But looking at the information in your post; especially the Skew-t, it looked like a relative easy ride up higher on top which looks not much above 5K. Looks like going a bit further south into Kentucky would also have avoided much of the threat as well. Of course if going above higher the pilot would need to be able to get above before the threatening area and not need to descend till past it - so depends on there intended destination. But appears not much of a detour south would be required at Mooney speeds.

The FL016 PIREP makes me very curious since I imagine that must be well below the MIA there. Could it VFR scud running getting into trouble? IFR descending on an approach or IFR and no longer able to maintain altitude? Scary! I made no effort to look at the planes proximity to airports but perhaps someone has that can shed some more light.
Scary flight! I assume they're okay.


Sent from my iPhone using Tapatalk

[Scott Dennstaedt, PhD]

21 minutes ago, kortopates said:

The FL016 PIREP makes me very curious since I imagine that must be well below the MIA there. Could it VFR scud running getting into trouble? IFR descending on an approach or IFR and no longer able to maintain altitude? Scary! I made no effort to look at the planes proximity to airports but perhaps someone has that can shed some more light.
Scary flight! I assume they're okay.

Paul,

It's hard to know for sure, but "punching through" these stratocumulus decks (on departure or arrival) can make for an exciting scenario. Even with a certified IPS, the SIGMET for severe ice means you are becoming a test pilot and operating outside the design envelope of the aircraft. In this case, the SIGMET was issued after the urgent PIREP, but any future aircraft launching through that stratocu deck better be operating on a waiver.     

[gsxrpilot]

I find the Icing overlay in ForeFlight to be very accurate. It's super useful for in-flight icing information. 

[Nick Pilotte]

I was flying to the north of that ice yesterday and my friend flew through it in his C510 on his way to Memphis.  Haven’t heard from him yet, but I knew he was headed there.  He returned the same evening though.  Maybe his cruise at FL310 was over most of it.  

[Ibra]

On 2/8/2020 at 10:26 PM, kortopates said:

The FL016 PIREP makes me very curious since I imagine that must be well below the MIA there. Could it VFR scud running getting into trouble? IFR descending on an approach or IFR and no longer able to maintain altitude?

At those altitides tends to be from airliners on approach 

I struggle to see how one can elect to cruise bellow MIA to avoid icing? -1000ft will not make any difference to icing (only few degres of temperature) but makes terrain & vfr in imc risks 1000000 more deadly (obviously none of this matters if one can't maintain height/speed)

Edited February 10, 2020 by Ibra

[carusoam]

A big invite for the iced Mooney pilot to join us... 

There is plenty of experience to be shared from this flight experience...

I saw ice build on the wings once.   But not 1.5”!

Ice does build rather quickly.

Best regards,

-a-

[kortopates]

5 hours ago, Ibra said:

At those altitides tends to be from airliners on approach 

I struggle to see how one can elect to cruise bellow MIA to avoid icing? -1000ft will not make any difference to icing (only few degres of temperature) but makes terrain & vfr in imc risks 1000000 more deadly (obviously none of this matters if one can't maintain height/speed)

I finally looked up where the planes was out of curiosity. If the PIREP location is accurate, the plane was on the 100 degree radial 10 miles out of KMTO. ILS for RWY 29 was right to his south, but the minimum altitude to cross the FAF was at 2400' at 4.8 miles from the field - ~5 miles further south west.  There is also Casey 1H8 with a GPS approach to RWY 22 the plane could have been headed for. The published MSA for MTO there is 2500', for Casey its 2600' and the OROCA there is 3200' . There are also some lighted obstacles in the planes vicinity at 1309' and 1440' .  

I doubt the pilot was that low by choice.

[Hank]

4 hours ago, kortopates said:

I finally looked up where the planes was out of curiosity. If the PIREP location is accurate, the plane was on the 100 degree radial 10 miles out of KMTO. ILS for RWY 29 was right to his south, but the minimum altitude to cross the FAF was at 2400' at 4.8 miles from the field - ~5 miles further south west.  There is also Casey 1H8 with a GPS approach to RWY 22 the plane could have been headed for. The published MSA for MTO there is 2500', for Casey its 2600' and the OROCA there is 3200' . There are also some lighted obstacles in the planes vicinity at 1309' and 1440' .  

I doubt the pilot was that low by choice.

With 1-1/2" of ice, he may not have had any other options . . . .

[Scott Dennstaedt, PhD]

12 hours ago, Ibra said:

At those altitides tends to be from airliners on approach 

I struggle to see how one can elect to cruise bellow MIA to avoid icing? -1000ft will not make any difference to icing (only few degres of temperature) but makes terrain & vfr in imc risks 1000000 more deadly (obviously none of this matters if one can't maintain height/speed)

I'm guessing this was on an approach to land or for a departure, not any kind of cruise altitude per se. 

Here's a tip for everyone.  When filing a PIREP for ice (or turbulence), be sure you give the altitudes or range of altitudes you were accreting ice or experiencing turbulence.  Don't just say, "icing on climb out".  That's because the Current Icing Product uses our PIREPs to help it do a better analysis.  And "icing on climbout" with a FL016, for example, would just strengthen the icing potential at 1600 ft MSL, not through the range of altitudes experienced. 

[Nick Pilotte]

Wow.  I needed to slow down and reread that.  I was reading that at FL160.  Still scary for a SEP plane.