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#1
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How long for thermals to start working after rain?
I am looking out the window of my office in Salt Lake City, Utah right
now to rain falling. Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. Might be a decent soaring day. How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. What have you all experienced? Thanks, Bruno - B4 |
#2
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How long for thermals to start working after rain?
On Fri, 23 Apr 2010 08:30:41 -0700 (PDT), Bruno
wrote: I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. What have you all experienced? Geology (terrain composition in the different layers) also strongly affects the time needed to restart the thermal cycle. I think geology is also relevant to the max thermal height and to the formation of convective clouds. Not to mention airmass humidity, wind, elevation and so on. AldoCernezzi |
#3
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How long for thermals to start working after rain?
On Apr 23, 11:30*am, Bruno wrote:
I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 I've found it to depend on the soil type. When I was a student pilot the simplified wisdom I received was "the day after a cold front." Then, after I got my license I would start to take days off to go soar but wound up spending my vacation time looking at overcast skies or (at best) grinding around in weak thermals. I started doing my own weather forecasting after that and found that usually the second day after the cold front was best where I lived (characterized by forested hills and clay soil). My instructor, meanwhile, had moved to New Jersey (characterized by sandy soil) and noted that the first day after the front was best. So, my answer is that "it depends". Since you live in a fairly arid climate zone, I would expect that very soon after the front would be best (especially with orographic lift available). -- Matt |
#4
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How long for thermals to start working after rain?
On Apr 23, 9:30*am, Bruno wrote:
I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 Just stay out of the valleys. During the Open Class Nationals in the UK in '93 or '94, it was raining and gray as the pilots' meeting started at 10am. All assumed it would be a rest day, but were astonished when CD Ken Sparkes called a grid time of 12:30pm. He'd been consulting with Tom Bradbury who was forecasting for the 15m Nats up country. Tom said there was a gap coming, and it would be soarable in the gap. We had Meteosat images and a contact out west who confirmed when the gap had arrived there, and indeed it was soarable in the gap. The gap slowed and arrived about 30 minutes late. The field launched and started, heading into the gap, dog-legged south to the second TP, back to TP3, and home again to Enstone as the gap closed. It was raining again as they were putting the gliders away. IIRC 37 of the 45 competitors finished the task. A few didn't start and one or two landed out. One of the UK's top senior pilots complimented Ken saying 'gutsiest call I've ever seen'. He was very proud to have called a contest day when no one else would have dared. Frank Whiteley |
#5
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How long for thermals to start working after rain?
On Apr 23, 9:10*am, Frank Whiteley wrote:
On Apr 23, 9:30*am, Bruno wrote: I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 Just stay out of the valleys. During the Open Class Nationals in the UK in '93 or '94, it was raining and gray as the pilots' meeting started at 10am. *All assumed it would be a rest day, but were astonished when CD Ken Sparkes called a grid time of 12:30pm. *He'd been consulting with Tom Bradbury who was forecasting for the 15m Nats up country. *Tom said there was a gap coming, and it would be soarable in the gap. *We had Meteosat images and a contact out west who confirmed when the gap had arrived there, and indeed it was soarable in the gap. *The gap slowed and arrived about 30 minutes late. *The field launched and started, heading into the gap, dog-legged south to the second TP, back to TP3, and home again to Enstone as the gap closed. *It was raining again as they were putting the gliders away. *IIRC 37 of the 45 competitors finished the task. *A few didn't start and one or two landed out. *One of the UK's top senior pilots complimented Ken saying 'gutsiest call I've ever seen'. *He was very proud to have called a contest day when no one else would have dared. Frank Whiteley On one of my first cross-country flights from Magalies Gliding Club (quite a few years ago), I ran into a light rain shower, tried to run under it and ended up on the ground as it killed all lift. As I waited for my retrieve crew, a thermal moved across the field, not half an hour after I had landed, and soon the sky filled up with lovely cumulus from horizon to horizon. The answer depends on how much rain, how dry the soil, how soon the sun and how unstable the air! Half-an-hour may be enough. Mike Mike |
#6
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How long for thermals to start working after rain?
On Apr 23, 11:30*am, Bruno wrote:
I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 It seems it is always too late! |
#7
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How long for thermals to start working after rain?
On Apr 23, 3:38*pm, AK wrote:
On Apr 23, 11:30*am, Bruno wrote: I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 It seems it is always too late! All very good things to thank about. Thanks for the replies. Soar safe! Bruno - B4 |
#8
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How long for thermals to start working after rain?
On Apr 23, 1:20*pm, Mike the Strike wrote:
On Apr 23, 9:10*am, Frank Whiteley wrote: On Apr 23, 9:30*am, Bruno wrote: I am looking out the window of my office in Salt Lake City, Utah right now to rain falling. *Tomorrow is expected to be in the mid to upper 60's and sunny with fairly low humidity. *Might be a decent soaring day. *How long does it take the ground to dry up enough after rain for thermal soaring conditions to get good again? *I am sure the answer might be different when the temps are in the 60's and 70's compared to 80's and 90's summer time. *What have you all experienced? Thanks, Bruno - B4 Just stay out of the valleys. During the Open Class Nationals in the UK in '93 or '94, it was raining and gray as the pilots' meeting started at 10am. *All assumed it would be a rest day, but were astonished when CD Ken Sparkes called a grid time of 12:30pm. *He'd been consulting with Tom Bradbury who was forecasting for the 15m Nats up country. *Tom said there was a gap coming, and it would be soarable in the gap. *We had Meteosat images and a contact out west who confirmed when the gap had arrived there, and indeed it was soarable in the gap. *The gap slowed and arrived about 30 minutes late. *The field launched and started, heading into the gap, dog-legged south to the second TP, back to TP3, and home again to Enstone as the gap closed. *It was raining again as they were putting the gliders away. *IIRC 37 of the 45 competitors finished the task. *A few didn't start and one or two landed out. *One of the UK's top senior pilots complimented Ken saying 'gutsiest call I've ever seen'. *He was very proud to have called a contest day when no one else would have dared. Frank Whiteley On one of my first cross-country flights from Magalies Gliding Club (quite a few years ago), I ran into a light rain shower, tried to run under it and ended up on the ground as it killed all lift. *As I waited for my retrieve crew, a thermal moved across the field, not half an hour after I had landed, and soon the sky filled up with lovely cumulus from horizon to horizon. The answer depends on how much rain, how dry the soil, how soon the sun and how unstable the air! *Half-an-hour may be enough. Mike Mike I'm with Mike - it depends. I've seen thermals within an hour or so after a light shower on an otherwise hot, sunny and dry day in mountainous terrain. I also recall a day at the standard nationals in Kansas where a lot of rain one day left soaked soil and standing water that killed thermals in some areas for a day or more. 9B |
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