The Weather Guessers got it Wrong

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kyleb

Final Approach
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Marietta, GA
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Drake the Outlaw
The Weather Channel, ADDS, and the other online resources predicted very light winds today in the Atlanta area.

When I was driving to the airport this morning, the car seemed to be jumping around a little on the interstate, like there were wind gusts or something. Impossible, I thought... there isn't supposed to be any wind today.

Then I called the FSS for an abbreviated briefing with a terminal forecast. Light surface winds, but 30 knots at 3,000'. Hmm, that's quite a shear, I thought. Kind of surprising that it won't create surface winds.

Got to the airport. Hmm, the pollen is blowing across the ramp. Flags and windsocks are flapping. There is an odd sensation against my face, almost like.... wind....

Checking the local reporting stations, winds were 15 G 21 at most of the nearby fields.

But I braved it anyway. And I was right about the shear - it was rough as anything under 3,000'. Above 4,000' it was nice and smooth.

How do the weather guessers get it so wrong?
 
The terminal at RYY was for ~6 knots @ 330 or thereabouts, per my abbreviated brief at 8:30 or so.

They updated it significantly by mid morning.
 
got my weather yesterday. Said it would be clear all day. Went to the airport and couldn't see across the runway due to fog.:mad2:
 
Anybody here could make a boatload of money by simply submitting 100% accurate weather forecasts.
 
scottd said:
Not a bad forecast. The gusts that were reported barely meet the criteria for gust factor.
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Yep, winds almost 50% higher than forecast plus unforecast gusts that exceeded the criteria for gust factor. Unforecast turbulence too.

Outstanding work. ;-)
 
scottd said:
The forecast was right in the middle of the actual winds recorded. So, I'm not sure how you can say that it's 50 percent higher? I'll repeat what I said...
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10 knots of actual wind at RYY vs 6 or 7 knots in the forecast is a 50% difference. See if you can dig up the actual winds at Dobbins or Falcon (FFC). I think you'll find that 10 knots (at RYY) was on the low side for the region, and that the gusts in the area exceeded 20 knots. In fact, I haven't refreshed one of the weather downloads on my iPhone, and it shows 12 knots at Dobbins from sometime (probably early afternoon) yesterday and 10 G17 at RYY.

The forecast wasn't a good projection of the conditions which existed. When I gave my pirep (turbulence) to the FSS, the guy said something like "Yeah, I'm not sure what happened, looks like a low level trough formed just N of Atlanta - these winds were not in the forecast."

As to whether the turbulence was thermal related, I'm not sure how you come to that conclusion. It was bumpy first thing in the morning and all day after that. Thermal turbulence doesn't start that early.
 
scottd said:
Let me know how that's working out for ya. :lol: Even more money if you could get 100 percent accuracy from the medical profession.
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By no means do I think I could provide a 100% accurate forecast. Notice also I'm not complaining about winds being a few knots off. In fact, I'm pretty impressed with the forecasts we do have. Seldom is it I launch and have to divert. Seems to me the weather is mostly 'as advertised'.
 
scottd said:
I guess we'll have to agree to disagree. When I look at all of the reports I don't see this as a major wind event. Here are all of the reports for the entire state of Georgia around 16Z...

<snipped to point out 4 relevant reports from Metro Atlanta>

KATL 131552Z 36013KT 10SM BKN250 19/02 A3004
KFTY 131553Z 34009G15KT 10SM CLR 19/02 A3004
KPDK 131553Z 35014G18KT 10SM CLR 20/01 A3004
KRYY 131547Z 34010G18KT 310V030 10SM BKN250 17/01 A3006


...it might be my degrees in meteorology and years of experience in aviation weather training...

<snip>

I realize that pilots don't get an education on how to recognize the potential for thermal turbulence. Quite a shame. But that's why I'm in the aviation weather training business.
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Hold all the training classes you want, wave the resume as high as you like, but yesterday's wind forecast was off by enough to matter. Nobody has claimed a major wind event. Rather than claiming that the forecast was good, why not explain what what caused the winds to develop well beyond what was forecast?

As to the pirep you noted in a later post, that was mine. Not a lot of people give those anymore, but I thought it was appropriate. The guys who were landing at VPC when I departed earlier in the day radioed "It is bumpy as <poop> below 3K", so it wasn't like I was the only person who noticed, regardless of who filed a pirep.
 
kyleb said:
Hold all the training classes you want, wave the resume as high as you like, but yesterday's wind forecast was off by enough to matter. Nobody has claimed a major wind event. Rather than claiming that the forecast was good, why not explain what what caused the winds to develop well beyond what was forecast?

As to the pirep you noted in a later post, that was mine. Not a lot of people give those anymore, but I thought it was appropriate. The guys who were landing at VPC when I departed earlier in the day radioed "It is bumpy as <poop> below 3K", so it wasn't like I was the only person who noticed, regardless of who filed a pirep.
Click to expand...

Can we at least define 'enough to matter'?
 
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