ForeFlight Echo Tops

M

mattcashore

Filing Flight Plan
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Display name:
Matt Cashore
Hi all-

New member and first post. Be gentle.

Can't figure out how to embed an image, so I'll do the best I can describing it. I had a scare some years ago flying IFR in and out of benign clouds around 8K. Popped out of one of the little guys just in time to see the 20,000-ish foot towering cumulus I was about to fly into. Yowsa. SCARY ride. It was a thunderstorm just being born so it was not yet making rain, so it did not show up on NEXRAD.

Brings me to my question: In an area of generally widespread green, ForeFlight sometimes shows echo tops of 210, 239, 225, etc. METARS in the area might show light rain, maybe 1000-foot ceilings, normal winds. Nothing scary on the surface in other words. But those echo tops nag at my brain. What do they actually mean? Is there another 20K foot monster embedded in the otherwise benign scud? I will stay away from areas that show sharp gradients from green to yellow to orange and beyond, but widespread areas of green *should* be reasonable, right??

Thanks very much!
 
It is important to remember that the information that shows up in your cockpit can be as much as eleven minutes old. You can't expect something that just popped up in front of you to be displayed immediately. The NEXRAD radars (individually) must complete their scans, then the data from several radars must be massaged into a coherent whole, then off it goes to the facility that broadcasts it to users. Takes time.

Bob Gardner
 
Welcome to POA. These are some resources I use especially in the stormy season. They may help you see if things look like they are going to be fairly stable or may change quickly on you. It could go from all green to scattered or widespread thunderstorms in a hurry. Remember that a 25,000' TS in Michigan will be stronger than than the same height in S. Florida. I really enjoy learning about weather even though I only fly VFR. It keeps my family safer and makes it a little easier to make that go/no-go decision. I got caught out once in very unstable conditions, solo, just after the ink was dry. Things went from a hazy 3000' overcast to cylinders of dark downpours everywhere within 10 minutes. There was lots of blowing dust, so I was not looking forward to the exciting landing. I went home and ordered a few books and started studying. This winter would be a good time to get the weather books out.

http://www.spc.noaa.gov/products/exper/enhtstm/
http://www.spc.noaa.gov/products/outlook/day1otlk.html
http://www.duats.com/graphics/natrad2x.html
http://cimss.ssec.wisc.edu/goes/rt/viewdata.php?product=ct_us
http://weather.unisys.com/upper_air/skew/
http://www.emc.ncep.noaa.gov/mmb/namsvrfcst/lift.animate.html#picture
http://www.nws.noaa.gov/mdl/radar/smv_03h_probltg.gif
http://weather.unisys.com/upper_air/ua_cont.php?plot=ki&inv=0&t=cur
http://www.emc.ncep.noaa.gov/mmb/namsvrfcst/lift.animate.html#picture
http://weather.unisys.com/upper_air/ua_cont.php?plot=tt&inv=0&t=cur
http://weather.unisys.com/nam/nam.php?plot=500&inv=0&t=4p
http://weather.unisys.com/nam/nam_misc.php?inv=0&plot=ehi
http://aviationweather.gov/ccfp
 
Does FF show tops while enroute via ADS-B?

I learned the hard way not to try to tactically fly through a hole with FF + Stratus 2 about a year and a half ago. First leg of the flight was around 3 hours of very nice flying - low, broken stratus which I managed to stay above for most of the trip. Uneventful landing into Roanoke. As I waited to fuel up for the second and last leg, about a 2 hour trip further south, I could already see little green cells popping up directly along my route. The plan was to "go up and take a look", and also to get off the ground as quickly as possible so as to avoid any CBs.

Well, if you've been around aviation at all, I'm sure you've heard that you can't outclimb growing CBs in a small Cessna 172SP. I tried, but after I reached 10k feet, I quickly realized all that sage advice was the truth. As I sat there pondering my fate, questioning whether or not to press on, and watching enviously at the jets soaring over me safely above all the growing cells, I decided to try and make it to what appeared to be a small gap in the weather about 50 miles ahead. Suffice it to say, those were the scariest 50 miles of flying I've had.

I managed to avoid visually the truly nasty stuff - if it looks dark, turn away. But, I did end up having to fly through the tops of quite a few growing CBs, one of which forced me to go to idle on the throttle momentarily to avoid an excessive RPM. And needless to say, the "gap" I saw on FF was nowhere in sight. Luckily that area of weather wasn't too bad, mostly just gave the plane a good soaking. But as soon as I came out on the other side, I requested a descent and just ducked under for the remainder of the trip.

I did learn one valuable piece of information on this trip - ATC is very, very accommodating when it comes to weather. I requested about a 20 degree deviation to the right, then to the left to go through the gap. They kept reminding me to inform when I was direct my destination, which I never did for most of the 2 hours - was literally on one side or the other of the main cell line the entire trip.

Oh... and to answer your question... this was entirely an area of "widespread green" with a few yellows sprinkled in (albeit along an approximately 20nm wide corridor, but otherwise very slowly moving & growing).
 
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DeckardTrinity, that's a great post and a very instructive story. Thanks for posting it.
 
This is why we have onboard radar.

In my personal plane, which doesn't have a radar pod, I just don't mess with IMC ops around that stuff. Plus it's been like 6 months since I took her IFR or broke 1500' AGL :D
 
Welcome back Scott. We miss your weather knowledge.
 
scottd said:
The echo top heights shown on ForeFlight represent the highest (tallest) MSL height where the radar returns are 18 dBZ or greater. This is much different than the heights reported on the Radar Summary Chart that I discuss here. ForeFlight does a pretty good job filtering out bad echo top heights that show up on other locations.

Nevertheless, the echo top heights reported on ForeFlight are not cloud tops and you won't see any reported below FL200. Generally speaking, the higher the echo tops the greater the updraft strength in the convection. So they are best used to evaluate the severity thunderstorms and not a good way to know you can top a particular area of weather or know whether or not it's safe to fly through a particular region. That answer comes from a more integrated analysis of the weather using more than just a single source such as echo top heights.
Click to expand...

Thanks. Is Foreflight going to integrate Skew-T information at some point in the future? Seems like an obvious addition at some point, but I suppose that technical issues could make it harder than I think.
 
scottd said:
We make a policy not to announce any new features in ForeFlight. But the number of pilots that use Skew-Ts is a very, very small number. It's a complex chart and we've got pilots who don't know how to use the ceiling layer on the map much less a Skew-T. So I'll leave it there.
Click to expand...

Good call. That would be a lot of effort and also bandwidth for something almost nobody would use.

Okay brace yourself for a shameless feature request :D

You know what would be really cool, would be a way to show "future radar" on whatever map you current are using as a prediction of where the models think the precip is going to be in 6 hours and 12 hours time. We can get that info digging around but having it there graphically would be a really nice feature.

</shameless feature request>
 
scottd said:
We make a policy not to announce any new features in ForeFlight. But the number of pilots that use Skew-Ts is a very, very small number. It's a complex chart and we've got pilots who don't know how to use the ceiling layer on the map much less a Skew-T. So I'll leave it there.
Click to expand...

Again, thanks for the response. This is helpful. At least I know not to hold my breath, and to make alternate arrangements.

Please note that this is NOT sarcastic. I really greatly appreciate you taking the time to respond. I know that it is not required, and that you took the time to respond is a great reflection on Foreflight. That I have come to expect great customer service from Foreflight is not an indication that I take it for granted.
 
Gubbins said:
Good call. That would be a lot of effort and also bandwidth for something almost nobody would use.

Okay brace yourself for a shameless feature request :D

You know what would be really cool, would be a way to show "future radar" on whatever map you current are using as a prediction of where the models think the precip is going to be in 6 hours and 12 hours time. We can get that info digging around but having it there graphically would be a really nice feature.

</shameless feature request>
Click to expand...

I use this one...

http://coolwx.com/ptype/
 
Is there any cross-referencing of radar echo tops with IR satellite data to show cloud tops rather than purely radar-based tops?

I can imagine that would be a pretty manual process and that doing something like that would be slow and not particularly useful in a tactical sense. But I don't know.
 
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