Danny Brotto wrote:...
I can tell you that the wave is quite active at WS and the bands can and do shift. The lulls and blasts IMO are due to the wave moving forward and back; I would not trust flying it in a flex wing in wave conditions unless you’re willing to put up with possible turbulence. As far as evening lulls, the wave often intensifies in the evening as disruptive convection ceases. I’ve broken down many times at WS when the anticipated evening lull turned into freight trains.
Danny Brotto
I've long suspected a prominent wave influence due to the upwind plateau and likelihood of wave harmonics propagation--I've flown a few bands myself though nothing like what Nelson has accomplished--who is expert on local wave conditions at Woodstock.
You mention evening freight trains when you anticipated lighter conditions after convective activity ceased. Would this be because the lower boundary layer--defined by convective activity--essentially disappears in effect causing wave harmonics to tighten or reach lower?
Danny Brotto wrote:.
Back in the day when WS was less flown, we did our stupid high-wind stuff at HR. I tended to be a windy-weenie even in those days but these launches were not atypical: see http://www.marylandhanggliding.org scout out the “photo gallery”, then “memorabilia” then “old HR photos” then “windy cliff launch” to see what I mean. The new ramp is not as conducive to high wind launches as the old ramp so it just doesn't happen... thank goodness.
"Would this be because the lower boundary layer--defined by convective activity--essentially disappears in effect causing wave harmonics to tighten or reach lower?"
Right, wave is broken up by convection. Typically the wave is above the thermal lift. Some taller thermals do poke into the wave and that's a doorway in. As the convection eases towards day-end, the wave shifts. I'm not saying that the blasts are due to the wave itself (I've yet to encounter wave at 1000 ft AGL) but from a newly altered flow being "diffrent" from the lull before the blast.
My point is that the winds are still there aloft--they may just be deflected higher or lower. I also maintain that no matter how good you may be at forecasting weather--you're still tossing the dice on high wind days as to whether or not those winds may make a guest appearance at launch or the LZ. I myself have chosen to accept those risks.
Over many years of flying it has been a general habit of pilots to assume Woodstock is the place to go on dynamic passing or post frontal days. That's just the way it has always been.
In general, when flying Woodstock I have seen way way too many launches where pilots have been gusted straight up--sometimes rolled. I have seen way way too many crashes, treeings and blowbacks. I've seen way way too many pilots get low up against the ridge and fail to get out to or barely make a suitable lz. I've seen way way too many rescue squads haul away busted up pilots from turbulent lz's.
Marc,
I agree wholeheartedly. And wave conditions are a whole different animal. Keep up the valuable inputs.
Every one's been talking about high winds aloft. Joe says the winds aloft were supposed to back down to 15 knots in the evening. I don't quite understand...unless there's a major shift in pressure patterns the winds aloft should not be affected by the diurnal cycle of the boundary layer.
Joe, if you're reading: what exactly are you referring to as 'winds aloft'? 900 mb? 850 mb? 700 mb? If one of the lower levels all the mechanisms people have named could screw up the forecast if the upper levels still have strong winds. I'm not adding anything new to the mix except to say that we have to be clear about what we discuss when we say 'winds aloft'. Some people are talking about launch level and moderate soaring levels (900-850 mb) where the forecast may have variable accuracy, others are talking about above the convective boundary layer (typically 700 mb) where the forecast should be close to spot-on.
Try 3000', 6000', and 9000' MSL. That's what the WX-BRIEF provides. Haven't used that in a while. The late Bill Bennett advised staying home when the 3000' MSL forecast is 20 knots or more. I know we regularly violate that advice. Bacil
That's about 900 mb, a bit above launch level. Near the surface every 100 mb drop corresponds to about 3000 feet. We definitely violate Bill's advice on a frequent basis.
Can we get some of you guys in-the-know to elaborate & simplify some of
this stuff for us. There are some chickens in the young hang 3 coop that are
getting a bit nervous over the current meteorlogical debate. You guys are being followed by at least one dumb bird. I'm embarrassed to be an H3 for over a year now and understand so little about weather conditions. Ignorance coulda/shoulda cost me my wings @ Woodstock 2 weeks ago when the wind ramped up late in the afternoon and wouldn't let me off the ridge.
I finnaly got out to the LZ but then let myself get pushed out of the box.
Flying a Falcon, and thinking of Joe, I didn't feel I could get back in safely
so I landed in the lower field by the river. (not reccomended either) If you
can help I'm all ears.
Kurt Hirrlinger wrote:Can we get some of you guys in-the-know to elaborate & simplify some of
this stuff for us. There are some chickens in the young hang 3 coop that are
getting a bit nervous over the current meteorlogical debate. You guys are being followed by at least one dumb bird. I'm embarrassed to be an H3 for over a year now and understand so little about weather conditions. Ignorance coulda/shoulda cost me my wings @ Woodstock 2 weeks ago when the wind ramped up late in the afternoon and wouldn't let me off the ridge.
I finnaly got out to the LZ but then let myself get pushed out of the box.
Flying a Falcon, and thinking of Joe, I didn't feel I could get back in safely
so I landed in the lower field by the river. (not reccomended either) If you
can help I'm all ears.
Kurt--don't be put off by all the huff-n-puff ...it has nothing to do with any special H4 knighthood/weather guru stuff.
My whole point is safety is a direct function of pilot judgement--and a part of that is understanding what you're getting into and what COULD possibly happen over the course of the day. Only YOU know if you're ready to deal with it.
Kurt,
I recommend lotsa reading and lotsa flying. The reading part should include Performance Flying and Understanding The Sky by Pagen. Those two books will help you learn more about the big picture. The flying will give you the experience necessary for advancing your skills and judgement. The key in flying is to always leave yourself an out, to keep a healthy safety margin and don't back yourself into a corner with no good options. In my opinion the Falcon does not provide you with a large enough window of performance to handle the myriad of weather conditions that we fly in with double surface gliders, and with a healthy safety margin. A prime example, in my opinion, is the very flight you describe from 2 weeks ago. An easy to fly double surface glider increases your range of flyable conditions, but the increased range brings increased risk as well. The common thread among all this is always leave yourself an out, no matter what glider you are flying.
Actually, there's been no weather debate in this thread. Just some suggestions about what may cause sudden increases in launch level winds and some redefinition of terms. But to summarize all the silent knowledge without the terminology, it goes like this:
1. Winds up high depend only on the pressure systems, which are big lumbering dinosaurs that don't change just because the sun goes down.
2. Winds near the surface will be lower because of friction.
3. Convection (thermals etc) will stir up the air, so that some of the high speed wind above gets mixed down lower. This is what causes winds down lower to pick up in the middle of the afternoon, then eventually turn into a dead layer sometime in the evening.
4. Wave action works better in stable air, so thermally air may both decrease the wave and also mix it around so the effects are more felt at launch level.
5. The "woodstock effect" is almost definitely caused by the higher ridge in front of launch, but the details of how exactly this interacts with the 4 points above is a matter of speculation.
6. If you make sure the winds up high are not too much stronger than what you're willing to fly in, you've eliminated the primary danger. This is where we tend to push our luck at woodstock.
The main thing I've learned as a graduate student in meteorology is that a good HG pilot knows as much or more about this stuff than most meteorologists. Only a few practicing meteorologists specialize in the type of stuff we are interested in, so follow Bacil's advice and you'll become one of the world elite in the micrometeorology of winds and thermals.
I was referring to the 3000 MSL FD for reporting stations in that area, found on NOAAs ADDS page. Bill Bennett's advice is sound, with the provisio that a trainer like a Falcon should probably not be flown high in anything greater than borderline soarable conditions (I now think).
There is a lot of talk of wave and high winds aloft. Good, we need to talk about that. But I saw no obvious signs of wave in the clouds that day. No long linear formations parallel to the ridge. At least not before I launched. I think that launching any type of HG into obvious wave conditions is extremely dangerous. To do so in a Falcon would be borderline psychotic.
And don't fool youself into thinking its safe just because the winds aloft seem reasonable. Strong thermal activity can be just as dangerous to an aircraft with super low wing loading and equipped with only weight shift controls. This, I think, is where I dropped the ball in assessing conditions.
-- Joe
brianvh wrote:Every one's been talking about high winds aloft. Joe says the winds aloft were supposed to back down to 15 knots in the evening. I don't quite understand...unless there's a major shift in pressure patterns the winds aloft should not be affected by the diurnal cycle of the boundary layer.
Joe, if you're reading: what exactly are you referring to as 'winds aloft'? 900 mb? 850 mb? 700 mb? If one of the lower levels all the mechanisms people have named could screw up the forecast if the upper levels still have strong winds. I'm not adding anything new to the mix except to say that we have to be clear about what we discuss when we say 'winds aloft'. Some people are talking about launch level and moderate soaring levels (900-850 mb) where the forecast may have variable accuracy, others are talking about above the convective boundary layer (typically 700 mb) where the forecast should be close to spot-on.
What were the signs of highly thermic activity that you feel you miss-evaluated at the time of launch? (Earlier activity reported from the LZ might be expected to die down by the time you launched). You mentioned the clouds: were they still showing tower development, etc? More details...please!
Not flying this weekend, need to get the fix by talking about it.
Nice synopsis Brian.
I think that was just the kind of overview Tim (Kurt) was asking for.
Thanks for summing it up.
That's such a good point about single surface gliders too.
Flying out in the flats (towing), the difference that a double surface provides you can be less obvious/critical. In the mountains, that higher-speed efficiency gives you more outs.
I finally got a new wing and I'll re-read the books that made no sense to me the first time. I digest spoon-fed info better though, thanks Brian!
How do I find and interpret current and predicted conditions?
Another approach you could use is the video "Weather to Fly". Some people learn better from watching/ listening than reading. It goes over the basics pretty well.
I have a copy somewhere...
Weather predictions do take practice. I learned by looking at the weather then make a prediction. How will the wind direction cange during the day? How will wind strength change during the day? Will it be gusty? What will be the top of lift? What site will work best? Write it down if that works for you (you don't have to share it with anybody) and see how the predictions compare to the conditions of the day and posted flight reports.
You will begin to see patterns emerge and it will get easier and faster.
Thanks for the report on your flight, Joe. I sure hope the future work on your wrist gives you optimum use. I've pounded in many a time and if there is one thing I've perfected (and it's not flare timing) it's letting go of the downtubes before hitting the ground.
air_medal wrote:And don't fool youself into thinking its safe just because the winds aloft seem reasonable. Strong thermal activity can be just as dangerous to an aircraft with super low wing loading and equipped with only weight shift controls. This, I think, is where I dropped the ball in assessing conditions.
-- Joe
brianvh wrote:Every one's been talking about high winds aloft. Joe says the winds aloft were supposed to back down to 15 knots in the evening. I don't quite understand...unless there's a major shift in pressure patterns the winds aloft should not be affected by the diurnal cycle of the boundary layer.
Joe, if you're reading: what exactly are you referring to as 'winds aloft'? 900 mb? 850 mb? 700 mb? If one of the lower levels all the mechanisms people have named could screw up the forecast if the upper levels still have strong winds. I'm not adding anything new to the mix except to say that we have to be clear about what we discuss when we say 'winds aloft'. Some people are talking about launch level and moderate soaring levels (900-850 mb) where the forecast may have variable accuracy, others are talking about above the convective boundary layer (typically 700 mb) where the forecast should be close to spot-on.
My earlier 35-40 mph limit referred to 700 mb.
I was flying my T2 at Woodstock on the day Joe pounded in at the main LZ and I landed earlier in the day (at the bridge field) after an hour aloft because I had concerns about the textured nature of the air there that day. My bump-tolerance has diminshed over the years and if I'm scared, I'm not having fun. Beer-thirty arrived early that day for me.
expletive deleted)
