Detailed Predictions for: Chelan
Launch Altitude (f): 3820
LZ Altitude (f): 1200
Sounding

Station:

KOTX

Date/Time:

19 AUG 2018

Temp/Wind data from:

NOAA Digital Forecast

Site Forecasts
Time
(Local)
High
Temp

Puddle
Temp

Wind
(mph)
Thermal
Ceiling

(ft)
Soaring
Ceiling

(ft)
Above
Launch

(ft)
Thermal
Type
Thermal
Index

(F)
5 AM Sun 59 59 N 9 2407 3820 0 Blue 4
6 AM Sun 59 59 N 9 2407 3820 0 Blue 4
7 AM Sun 61 61 N 8 2417 3820 0 Blue 6
8 AM Sun 64 64 N 9 2448 3820 0 Blue 9
9 AM Sun 68 70 N 10 2650 3820 0 Blue 15
10 AM Sun 73 76 N 12 3274 3820 0 Blue 21
11 AM Sun 77 81 N 13 4291 3820 0 Blue 26
12 Noon Sun 81 87 NE 7 10338 5453 1633 Blue 32
1 PM Sun 84 90 NE 9 11674 9267 5447 Blue 35
2 PM Sun 86 92 NE 8 12077 11389 7569 Blue 37
3 PM Sun 87 92 NE 8 12077 11389 7569 Blue 37
4 PM Sun 88 91 NE 8 11879 11137 7317 Blue 36
5 PM Sun 87 89 NE 8 11466 8348 4528 Blue 34
6 PM Sun 85 86 NE 8 8582 4842 1022 Blue 31
7 PM Sun 82 82 N 7 4579 3820 0 Blue 27
8 PM Sun 78 78 N 8 3635 3820 0 Blue 23
9 PM Sun 75 75 N 8 3158 3820 0 Blue 20
10 PM Sun 72 72 N 7 2825 3820 0 Blue 17
11 PM Sun 70 70 N 10 2650 3820 0 Blue 15
12 Midnight Mon 69 69 N 12 2598 3820 0 Blue 14
1 AM Mon 68 68 N 12 2547 3820 0 Blue 13
2 AM Mon 67 67 N 13 2496 3820 0 Blue 12
3 AM Mon 65 65 N 12 2459 3820 0 Blue 10
4 AM Mon 63 63 N 10 2437 3820 0 Blue 8
5 AM Mon 62 62 N 10 2426 3820 0 Blue 7
6 AM Mon 62 62 N 10 2426 3820 0 Blue 7
7 AM Mon 64 64 N 12 2448 3820 0 Blue 9
8 AM Mon 66 66 N 12 2470 3820 0 Blue 11
9 AM Mon 69 71 N 14 2719 3820 0 Blue 16
10 AM Mon 73 76 N 16 3274 3820 0 Blue 21
11 AM Mon 76 81 N 18 4291 3820 0 Blue 26
12 Noon Mon 79 85 N 17 7314 4557 737 Blue 30
1 PM Mon 81 87 NE 17 10338 5453 1633 Blue 32
2 PM Mon 83 89 NE 17 11466 8348 4528 Blue 34
3 PM Mon 85 90 NE 15 11674 9267 5447 Blue 35
4 PM Mon 86 90 NE 14 11674 9267 5447 Blue 35
5 PM Mon 86 88 N 12 11212 7087 3267 Blue 33
6 PM Mon 84 85 NE 10 7314 4557 737 Blue 30
7 PM Mon 81 81 NE 9 4291 3820 0 Blue 26
8 PM Mon 78 78 NE 8 3635 3820 0 Blue 23
9 PM Mon 75 75 NE 7 3158 3820 0 Blue 20
10 PM Mon 72 72 NE 7 2825 3820 0 Blue 17
11 PM Mon 70 70 NE 6 2650 3820 0 Blue 15
12 Midnight Tue 68 68 NE 6 2547 3820 0 Blue 13
1 AM Tue 66 66 NE 6 2470 3820 0 Blue 11
2 AM Tue 65 65 N 6 2459 3820 0 Blue 10
3 AM Tue 64 64 N 6 2448 3820 0 Blue 9
4 AM Tue 63 63 N 6 2437 3820 0 Blue 8
5 AM Tue 62 62 N 7 2426 3820 0 Blue 7
6 AM Tue 62 62 N 6 2426 3820 0 Blue 7
7 AM Tue 63 63 N 7 2437 3820 0 Blue 8
8 AM Tue 66 66 N 8 2470 3820 0 Blue 11
9 AM Tue 69 71 N 8 2719 3820 0 Blue 16
10 AM Tue 73 76 N 7 3274 3820 0 Blue 21
11 AM Tue 77 82 N 6 4579 3820 0 Blue 27
12 Noon Tue 80 86 N 6 8582 4842 1022 Blue 31
1 PM Tue 82 88 NE 6 11212 7087 3267 Blue 33
2 PM Tue 84 90 NE 6 11674 9267 5447 Blue 35
3 PM Tue 85 90 NE 6 11674 9267 5447 Blue 35
4 PM Tue 85 89 E 6 11466 8348 4528 Blue 34
5 PM Tue 84 86 E 6 8582 4842 1022 Blue 31
6 PM Tue 82 83 E 5 4866 3985 165 Blue 28
7 PM Tue 79 79 E 5 3815 3820 0 Blue 24
8 PM Tue 76 76 E 5 3274 3820 0 Blue 21
9 PM Tue 73 73 NE 5 2936 3820 0 Blue 18
10 PM Tue 70 70 NW 5 2650 3820 0 Blue 15
11 PM Tue 68 68 NW 5 2547 3820 0 Blue 13
12 Midnight Wed 66 66 NW 5 2470 3820 0 Blue 11
1 AM Wed 65 65 NW 5 2459 3820 0 Blue 10
2 AM Wed 64 64 NW 5 2448 3820 0 Blue 9
3 AM Wed 63 63 NW 3 2437 3820 0 Blue 8
4 AM Wed 62 62 NW 3 2426 3820 0 Blue 7
5 AM Wed 61 61 NW 5 2417 3820 0 Blue 6
6 AM Wed 61 61 W 5 2417 3820 0 Blue 6
7 AM Wed 63 63 W 5 2437 3820 0 Blue 8
8 AM Wed 66 66 W 5 2470 3820 0 Blue 11
9 AM Wed 71 73 SW 5 2936 3820 0 Blue 18
10 AM Wed 76 79 S 5 3815 3820 0 Blue 24
11 AM Wed 81 85 S 5 7314 4557 737 Blue 30
12 Noon Wed 84 89 S 6 11466 8348 4528 Blue 34
1 PM Wed 86 92 S 7 12077 11389 7569 Blue 37
2 PM Wed 88 93 SW 8 12290 11609 7789 Blue 38
3 PM Wed 89 94 SW 9 12736 11815 7995 Blue 39
4 PM Wed 90 93 SW 10 12290 11609 7789 Blue 38
5 PM Wed 89 91 SW 9 11879 11137 7317 Blue 36
6 PM Wed 87 88 SW 9 11212 7087 3267 Blue 33
7 PM Wed 83 83 SW 9 4866 3985 165 Blue 28
8 PM Wed 78 78 W 10 3635 3820 0 Blue 23
9 PM Wed 74 74 W 10 3047 3820 0 Blue 19
10 PM Wed 70 70 W 10 2650 3820 0 Blue 15
11 PM Wed 68 68 W 10 2547 3820 0 Blue 13
12 Midnight Thu 66 66 W 10 2470 3820 0 Blue 11
1 AM Thu 64 64 W 10 2448 3820 0 Blue 9
2 AM Thu 63 63 W 10 2437 3820 0 Blue 8
3 AM Thu 62 62 W 10 2426 3820 0 Blue 7
4 AM Thu 61 61 W 10 2417 3820 0 Blue 6
5 AM Thu 60 60 W 9 2412 3820 0 Blue 5
6 AM Thu 60 60 W 9 2412 3820 0 Blue 5
7 AM Thu 61 61 W 9 2417 3820 0 Blue 6
8 AM Thu 64 64 W 9 2448 3820 0 Blue 9
9 AM Thu 67 68 W 9 2547 3820 0 Blue 13
10 AM Thu 72 75 W 9 3158 3820 0 Blue 20
11 AM Thu 75 79 W 7 3815 3820 0 Blue 24
12 Noon Thu 78 83 W 7 4866 3985 165 Blue 28
1 PM Thu 80 85 W 7 7314 4557 737 Blue 30
2 PM Thu 82 87 W 7 10338 5453 1633 Blue 32
3 PM Thu 83 87 W 7 10338 5453 1633 Blue 32
4 PM Thu 83 86 W 7 8582 4842 1022 Blue 31
5 PM Thu 82 84 W 16 5666 4272 452 Blue 29
6 PM Thu 79 80 W 16 4001 3820 0 Blue 25
7 PM Thu 75 75 W 16 3158 3820 0 Blue 20
8 PM Thu 71 71 W 16 2719 3820 0 Blue 16
9 PM Thu 67 67 W 16 2496 3820 0 Blue 12
10 PM Thu 64 64 W 16 2448 3820 0 Blue 9
11 PM Thu 62 62 W 10 2426 3820 0 Blue 7
12 Midnight Fri 60 60 W 10 2412 3820 0 Blue 5
1 AM Fri 59 59 W 10 2407 3820 0 Blue 4
2 AM Fri 58 58 W 10 2403 3820 0 Blue 3
3 AM Fri 57 57 W 10 2398 3820 0 Blue 2
4 AM Fri 56 56 W 10 2393 3820 0 Blue 1
5 AM Fri 56 56 W 10 2393 3820 0 Blue 1
6 AM Fri 56 56 W 10 2393 3820 0 Blue 1
7 AM Fri 57 57 W 10 2398 3820 0 Blue 2
8 AM Fri 60 60 W 10 2412 3820 0 Blue 5
9 AM Fri 64 65 W 10 2459 3820 0 Blue 10
10 AM Fri 69 71 W 10 2719 3820 0 Blue 16
11 AM Fri 73 77 W 8 3455 3820 0 Blue 22
12 Noon Fri 77 81 W 8 4291 3820 0 Blue 26
1 PM Fri 79 84 W 8 5666 4272 452 Blue 29
2 PM Fri 80 85 W 8 7314 4557 737 Blue 30
3 PM Fri 81 85 W 8 7314 4557 737 Blue 30
4 PM Fri 81 84 W 8 5666 4272 452 Blue 29
5 PM Fri 80 82 W 10 4579 3820 0 Blue 27
6 PM Fri 78 79 W 10 3815 3820 0 Blue 24
7 PM Fri 75 75 W 10 3158 3820 0 Blue 20
8 PM Fri 72 72 W 10 2825 3820 0 Blue 17
9 PM Fri 69 69 W 10 2598 3820 0 Blue 14
10 PM Fri 66 66 W 10 2470 3820 0 Blue 11
11 PM Fri 63 63 W 8 2437 3820 0 Blue 8
12 Midnight Sat 61 61 W 8 2417 3820 0 Blue 6
1 AM Sat 59 59 W 8 2407 3820 0 Blue 4
2 AM Sat 58 58 W 8 2403 3820 0 Blue 3
3 AM Sat 56 56 W 8 2393 3820 0 Blue 1
4 AM Sat 56 56 W 8 2393 3820 0 Blue 1

DISCLAIMER: These estimates are intended to assist in daily site selection only.  No warranty is made concerning the accuracy of these estimates.  These estimates cannot be used to determine if conditions are safe for flying.  Conditions should be evaluated at the launch site by experienced pilots before launching.

Sounding: This is the site at which the weather balloon was released.  If the flying site predicted is far from the sounding site, the estimate is not valid.  Also, the sounding is done at 12Z (4AM PST).  If a front comes through, the sounding is no longer valid. The sounding becomes less valid later in the day.

Thermal Ceiling: the lower of the height at which the thermal stops rising and the cloud level.  We can't fly into the clouds, so it doesn't matter how much higher the thermal goes.  Remember that we can't get to the top of the thermal because of our sink rate.  Our upper limit will be lower than the reported ceiling.

Soaring Ceiling: We will stop going up when the thermal is rising just fast enough to offset our sink.  It is estimated that this happens when the temperature difference between the thermal and the surrounding air is about 2 degrees F. This number is an estimate of the maximum altitude we might reach if we start at launch height, and should be more reflective of our chances of soaring than the thermal top. Please let me know how this compares with actually flying, and I will adjust it as necessary.

Above Launch: The difference between how high we might get and how high we start. This estimate does not account for ridge lift.

High Temp: This estimate is taken from the National Weather Service website.  Puddle temperatures can exceed this temperature. 

Puddle Temp: This estimate is based on the High Temp and the National Weather Service estimate of cloudiness, and the angle of the sun.  When the sun is directly overhead on a sunny day, the puddle temp is esimated to be 25 degrees warmer than the high ambient temperature. This estimate now includes a rigorous calculation of the Sun Angle, and accounts for the seasonal differences in zenith and daylight hours.

Wind: This estimate is taken from the National Weather Service website.

Thermal Type: Blue (no cloud formation) or White (Cloud formation)

Thermal Index: This is the maximum difference in temperature between the rising packet of air (the thermal) and the surrounding air.  The difference in temperature is responsible for the buoyancy of the thermal, and larger temperature differences mean faster rising thermals.  A value of about 10 F or greater often means that the conditions are soarable.  Values above 20 could indicate rowdy thermals.

Validity of estimate: Many factors (including strong wind, fronts, cloud shadows, incorrectly predicted temperatures, etc) can affect the validity of the estimates. 

Author: Tad Hurst

Supported By: Alan Crouse ac_soaring@yahoo.com