Village needs serum; its on the deck and cold.

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
A hypothetical.

You need to get out: SE piston, non-deiced.
The location is west Texas, 4500'msl
Temp/DP spread is nil, its cold. Thick clouds, no breaks, no light areas.

1. skew T guys, where are the tops?
2. how bad do you think the ice will be; why?

The hours are slightly off, metar and charts - ignore.

KE38 041735Z AUTO 08003KT 1/2SM OVC002 M02/M02 A3015 RMK AO2 T10201022
KE38 041715Z AUTO 08004KT 1/4SM OVC002 M02/M02 A3015 RMK AO2 T10231025
KE38 041655Z AUTO 09005KT 1/4SM OVC002 M02/M02 A3016 RMK AO2 T10231025
KE38 041635Z AUTO 07006KT 1/4SM OVC002 M02/M02 A3017 RMK AO2 T10231025
KE38 041615Z AUTO 09006KT 1/4SM OVC002 M02/M02 A3018 RMK AO2 T10231025
KE38 041555Z AUTO 08007KT 1/2SM OVC002 M02/M02 A3018 RMK AO2 T10231025
 

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It's clear at my house, so the tops are at 5200 roughly... It's getting warmer and the ceilings have been lifting a little in the past 45 mins. How soon will the villagers die? Can they wait an hour?
 
How far west are you in Texas? and where are you going to....and coming from?
 
The metar gives the airport involved.
We are only concerned with the hypothetical of a departure.
I will try to pinpoint the dep. on the charts with a blue dot, above.
Nope, can't skate around the issue by adjusting the dep. time. Gots to leave now (well, at the time of the metar) and deal with whatever hits the fan.
 
Well then climb like you can and get up out of it fast... Or let the villagers die.... However, a SE piston non iced and it might just be that the villagers AND you die.
 
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Stay on the ground... I don't know of any good way to forecast cloud deck thickness.
 
let the villagers die.... However, a SE piston nin iced and it might just be that the villagers AND you die.
Click to expand...

haha; we actually had a case slightly similar about 12 years ago. Widespread freezing rain and a couple had a funeral in the panhandle they absolutely had to attend. Roads so slick you could barely drive to the airport and they were begging any pilot they knew to take them to lubbock or amarillo, can't remember.
Finally 'got it' when a pilot told them if they talked someone into taking the flight, there would be 4 funerals instead of the one.
 
Jeanie said:
Well then climb like you can and get up out of it fast... Or let the villagers die.... However, a SE piston nin iced and it might just be that the villagers AND you die.
Click to expand...
Kirk: "He'll die in there!"
Scotty: "Captain -- he's dead already."

The accident files are so full of bad decisions by MedEvac operators that they're busy writing a whole new pack of rules on risk managment for them In the military, we called it a "misplaced sense of urgency." And it's killed a lot of people unnecessarily.
 
Let'sgoflying! said:
A hypothetical.

You need to get out: SE piston, non-deiced.
The location is west Texas, 4500'msl
Temp/DP spread is nil, its cold. Thick clouds, no breaks, no light areas.

1. skew T guys, where are the tops?
2. how bad do you think the ice will be; why?

The hours are slightly off, metar and charts - ignore.

KE38 041735Z AUTO 08003KT 1/2SM OVC002 M02/M02 A3015 RMK AO2 T10201022
KE38 041715Z AUTO 08004KT 1/4SM OVC002 M02/M02 A3015 RMK AO2 T10231025
KE38 041655Z AUTO 09005KT 1/4SM OVC002 M02/M02 A3016 RMK AO2 T10231025
KE38 041635Z AUTO 07006KT 1/4SM OVC002 M02/M02 A3017 RMK AO2 T10231025
KE38 041615Z AUTO 09006KT 1/4SM OVC002 M02/M02 A3018 RMK AO2 T10231025
KE38 041555Z AUTO 08007KT 1/2SM OVC002 M02/M02 A3018 RMK AO2 T10231025
Click to expand...
I will go as far as to show what I think is the skewT for this area at that time. You might check the lat/longs to be sure. I had to figure out where in West Texas it was. I'm guessing the tops to be around 7,500'. I'm wondering why the METARS show negative surface temps but it doesn't seem that way from the chart.

20111204-qjyrrba3hy3atjkhkqgj885ttm.png
 
103.68w 30.38n is correct, depicted on my charts post #1 with a colored dot.
It was freezing here, did you catch that it is almost 5K asl?
 
Let'sgoflying! said:
did you catch that it is almost 5K asl?
Click to expand...
Yes, that's why the temp and dew point measurements (red and blue lines) only extend down to the 5,000 mark.

Yellow line is the 5,000' MSL level. Green line is the 0C line. Anything to the right of the green line is supposedly above freezing.

I am only a novice at interpreting these things. Maybe someone else will chime in.

20111204-rgutar8wbxxkjka8d93j7888xs.png
 
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Ah, gotcha Mari. I see it now.
I wonder if the time diff has made the sfc. temps >0, a little later than the metar.
So where the T and DP lines split is where the tops are predicted? (7500')
Thanks.
 
Drive the serum there...
Click to expand...

Of course, but it's a thread about ice.


My suggestion is that there are likely a lot of clouds with potential ice which are truly Ø and we do not have a good way to identify them. Neither is there motivation to ascertain which are safe vs which aren't. (No worries; I have no plans to do my own research. I discourage others as well.)

This am, I suspected the cloud cover described was no greater than trace, (but could not know of course). I was hiking in it, good thick cloud layer but flat bases (no evidence of lifting, no convection), and below was bone dry. Despite zero T/DP spread, I couldn't see my breath.
I have flown in similar clouds a few times (with KI equipmt), seems to confirm my theory.
(Not about to try it in the Bellanca. Just discussing.)

What about the prediction chart?
 
This is all over my head...I am watching this to learn...
 
Let'sgoflying! said:
I wonder if the time diff has made the sfc. temps >0, a little later than the metar.
So where the T and DP lines split is where the tops are predicted? (7500')
Thanks.
Click to expand...
Here's the plot from a couple hours earlier. The temperature looks closer to freezing in this one. The tops look higher at this point too, closer to 10,000'.

20111205-cirgesi9tjtjsxkauuh8i9kq5b.png
 
Dave:

Was there an airmet for icing?
Were there any pireps of icing?
Skew-t really isn't rocket science. When temp and dew separate that may mean a break in the clouds there.

Perhaps I'm a little more used to this in the northland - but I've flown in clouds many times that were below freezing and picked up absolutely no ice.

When I realize my flight is going to involve precip below freezing I automatically assume it's a no-go. After I've made that decision I then start looking for evidence to change my mind. Some of the things I take into consideration:

1.) Do I have an out? If I can just safely descend out of it, then I'm not really worried about it.
2.) Are there any airmets for icing?
3.) Are there any pireps for icing?
4.) What does the skew-t say with regards to tops? How much can I limit my exposure
5.) I've been known to literally call the omaha tracon and ask them to ask the last aircraft that departed what the tops were and if they picked up ice. Seriously, they've gladly accommodated this request for me before. It *really* helps you make a decision.

It takes quite a bit of supporting evidence for me to decide to over-ride my automatic no-go decision above. But if there is enough - then I will. I've yet to scare myself in the clouds.
 
Let'sgoflying! said:
A hypothetical.

You need to get out: SE piston, non-deiced.
The location is west Texas, 4500'msl
Temp/DP spread is nil, its cold. Thick clouds, no breaks, no light areas.
Click to expand...

I attended an EMS conference 20 years ago that showed mortality rates by county on one slide and population density on the other (using shades of colors). The slides were nearly polar opposites of each other. The simple truth is, the resources do not exist in rural areas that do in populated areas. I have no doubt the relative trends persist to this day.

If you want to live in the country, you should know up front, the chances are, you will die in the country.

This scenario is a recipe for certain death. The village made its choice. I'm making mine. No go.
 
If I lived where Dave lived and got sick, I'd start barking and go see the vet! :wink2:
 
SCCutler said:
If I lived where Dave lived and got sick, I'd start barking and go see the vet! :wink2:
Click to expand...

That's okay for illness but don't go in with a broken leg...
 
This scenario is a recipe for certain death.
Click to expand...

I guess this is where we disagree. I have been through such clouds (KI a/c) and little to no ice. Clear lack of certain death.

I think a significant part of our assumption of "below 5C + visible moisture=ice' is incorrect.

And that it has not been worthwhile to anyone to refine it. I can live with that. Just wondering what others have observed, such as Jesse's post.
 
How bad will the ice be?

Just bad enough to kill you..
 
Which direction am I flying? and how quick can I get ahead or behind the system? Understanding the front and which sector I am going to be exposed to makes a huge difference. Im a huge fan of the ADDS FIP/CIP...Ive found it to be a pretty accurate tool and the FIP tends to actually over predict the icing conditions that are reality the next morning...Moreover the moisture origination of this system is a consideration... a maritime system tends to carry more moisture and be more heavily stratified than a continental system.
 
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Mari, you are spot on in your interpretation of both SkewT-LogP diagrams. What is missing is the analysis from the satellite comparing temperature on the Look down to the temps at what we think are the tops. If they are a match, then we have separate confirmation of the tops.

Taters is spot on and the quantitation of his sense is that during the period of graph where the red and blue lines coincide, the slope is fairly positive, and suggest supersaturated air, e.g, droplets/ crystals etc.

So if on the first Skew T you find the surface below freezing, the prediction (SKewT -Log p is a prediction unless you are at the 0600 and 1800 hour sounding releases and are at one of the 400 airports where that happens) you know the forecaster was off and that warm nose between surface (5000) and 7,000 (?tops) will not be "warm" and you will get clobbered with clear ice.

Guys and Women who have been flying a long time for utility have the right sense about maritime lows come ashore- this is just the quantitation of same.
 
Somewhat later, there is intermittent precip, moisture sticking to objects, it is colder. Still no airmet or sigmet but it certainly does not feel conducive to a non-KI flight. I think the Icingprob chart has it d.n. on. (and all that is low level, when you scroll through the altitudes available)
Mari, are you able to provide your magic sT chart again?
KE38 060555Z AUTO 03008KT 4SM OVC004 M07/M08 A3029 RMK AO2 T10731076
KE38 060535Z AUTO 03009KT 5SM BKN004 OVC010 M07/M07 A3029 RMK AO2 T10721075
KE38 060515Z AUTO 05008KT 5SM OVC004 M07/M07 A3028 RMK AO2 T10721075
KE38 060455Z AUTO 05009KT 5SM OVC004 M07/M08 A3028 RMK AO2 T10731076
 

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Let'sgoflying! said:
Somewhat later, there is intermittent precip, moisture sticking to objects, it is colder. Still no airmet or sigmet but it certainly does not feel conducive to a non-KI flight. I think the Icingprob chart has it d.n. on. (and all that is low level, when you scroll through the altitudes available)
Mari, are you able to provide your magic sT chart again?
KE38 060555Z AUTO 03008KT 4SM OVC004 M07/M08 A3029 RMK AO2 T10731076
KE38 060535Z AUTO 03009KT 5SM BKN004 OVC010 M07/M07 A3029 RMK AO2 T10721075
KE38 060515Z AUTO 05008KT 5SM OVC004 M07/M07 A3028 RMK AO2 T10721075
KE38 060455Z AUTO 05009KT 5SM OVC004 M07/M08 A3028 RMK AO2 T10731076
Click to expand...
Lucky I am still awake. :rofl:

20111206-d2fjqyskjxc28d1akndk6y6t3m.jpg


It looks like it's colder tonight than the other day and the tops are almost 10,000. Look at the windshear at about that level. Do you have an upslope or something? It would be an upslope in Denver but I don't know where you are in relation to the mountains or higher terrain.
 
Wow. That SkewT is a no go for me, FIKI and all. That is supersaturated air between 0 and minus 10C.


Bruce
 
late to the party. tops will be around 7000' IF, IF, IF, IF the model skew-T verifies.

when its a tight fit on go or no go, don't rely on one model and don't rely on one model run. Look at previous runs, how have they verified?

compare observations, is the barometer rising? has the moisture axis moved downstream of you? weather trend better or worsening?
 
Here is the skew-T that Eversky posted, with the relevant items highlighted.

The Moisture and Temp lines are actual (or forecast actual) temps and dewpoints with height, the 0 (Celsius) line runs from bottom center up and right to the center of the right side of the diagram. The temp lines all angle from lower left to upper right, (hence the name "Skew-T", the Temp lines are skewed)

Notice where the Temp and the dew point lines are on top of each other, from the bottom of the chart (ground) to just below 700mb (read on the left) or 10K' (read on the right). That is a saturated layer, and since the temps (red stay between the -10 and the 0 temp lines (isotherms) you know not only is it below freezing, but its in a zone in which moisture can exist in liquid form AND frozen form. The liquid form is what will deposit on an aircraft. An interesting thing can happen, in this zone, the RH can exceed 100%, with potentially explosive ice formation. This is the "supersaturated" layer that Dr. Bruce was mentioning. Major ice danger here.

Notice also the wind depiction on the right, NE winds in the saturated layer, are likely (look upstream at surface temps) bringing in additional subfreezing air, at best likely NOT bringing in warmer air. Also look how strong the winds up high are (25K+). Somewhat dicey w/out looking around at other sites, but likely an indication of rising motion in lower levels, which would lead to enhanced production of precipitation (bigger, heavier drops).

As icy as this sounding is, it doesn't appear that its particularly convective or unstable, so it could be worse!
 

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Man, James, I love it when you do your weather-mojo thing.

Keep it up, and...

...thanks!
 
SCCutler said:
Man, James, I love it when you do your weather-mojo thing.

Keep it up, and...

...thanks!
Click to expand...

I agree... I love to analyze weather and there is soooo much I don't know. It would be great if they added it into the school system as a required subject. As SC said, James, keep feeding us the finer details of out planets shield.

Ben.
 
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