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

Station:

KOTX

Date/Time:

20 AUG 2019

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 Tue 61 61 N 5 2486 3820 0 Blue 4
6 AM Tue 61 61 N 5 2486 3820 0 Blue 4
7 AM Tue 62 62 NW 5 2509 3820 0 Blue 5
8 AM Tue 64 64 NW 5 2555 3820 0 Blue 7
9 AM Tue 68 69 N 5 2668 3820 0 Blue 12
10 AM Tue 71 74 NE 3 2781 3820 0 Blue 17
11 AM Tue 75 79 E 3 3422 3820 0 Blue 22
12 Noon Tue 79 83 E 3 7265 3820 0 Blue 26
1 PM Tue 83 88 SE 5 8093 7540 3720 Blue 31
2 PM Tue 86 89 S 5 8527 7653 3833 Blue 32
3 PM Tue 88 91 S 5 10620 8050 4230 Blue 34
4 PM Tue 89 91 S 5 10620 8050 4230 Blue 34
5 PM Tue 89 90 S 5 10152 7826 4006 Blue 33
6 PM Tue 87 87 S 5 7868 7410 3590 Blue 30
7 PM Tue 84 84 S 5 7439 4396 576 Blue 27
8 PM Tue 81 81 S 5 4453 3820 0 Blue 24
9 PM Tue 78 78 S 6 3242 3820 0 Blue 21
10 PM Tue 76 76 SW 7 2880 3820 0 Blue 19
11 PM Tue 74 74 W 8 2781 3820 0 Blue 17
12 Midnight Wed 72 72 W 8 2736 3820 0 Blue 15
1 AM Wed 70 70 W 8 2690 3820 0 Blue 13
2 AM Wed 68 68 W 8 2645 3820 0 Blue 11
3 AM Wed 67 67 W 8 2623 3820 0 Blue 10
4 AM Wed 65 65 W 8 2578 3820 0 Blue 8
5 AM Wed 64 64 W 8 2555 3820 0 Blue 7
6 AM Wed 64 64 W 7 2555 3820 0 Blue 7
7 AM Wed 65 65 W 6 2578 3820 0 Blue 8
8 AM Wed 68 68 W 5 2645 3820 0 Blue 11
9 AM Wed 71 72 W 5 2736 3820 0 Blue 15
10 AM Wed 74 76 W 5 2880 3820 0 Blue 19
11 AM Wed 77 78 W 5 3242 3820 0 Blue 21
12 Noon Wed 79 80 W 8 3616 3820 0 Blue 23
1 PM Wed 81 83 W 10 7265 3820 0 Blue 26
2 PM Wed 81 82 W 13 5729 3820 0 Blue 25
3 PM Wed 80 81 W 12 4453 3820 0 Blue 24
4 PM Wed 79 79 W 10 3422 3820 0 Blue 22
5 PM Wed 76 76 W 14 2880 3820 0 Blue 19
6 PM Wed 74 74 W 14 2781 3820 0 Blue 17
7 PM Wed 71 71 W 12 2713 3820 0 Blue 14
8 PM Wed 69 69 W 9 2668 3820 0 Blue 12
9 PM Wed 67 67 W 9 2623 3820 0 Blue 10
10 PM Wed 65 65 W 9 2578 3820 0 Blue 8
11 PM Wed 64 64 W 9 2555 3820 0 Blue 7
12 Midnight Thu 63 63 W 9 2532 3820 0 Blue 6
1 AM Thu 62 62 W 9 2509 3820 0 Blue 5
2 AM Thu 61 61 W 9 2486 3820 0 Blue 4
3 AM Thu 60 60 W 8 2464 3820 0 Blue 3
4 AM Thu 59 59 W 6 2441 3820 0 Blue 2
5 AM Thu 58 58 W 5 2418 3820 0 Blue 1
6 AM Thu 58 58 W 5 2418 3820 0 Blue 1
7 AM Thu 59 59 W 5 2441 3820 0 Blue 2
8 AM Thu 60 60 W 5 2464 3820 0 Blue 3
9 AM Thu 64 65 W 5 2578 3820 0 Blue 8
10 AM Thu 67 69 W 5 2668 3820 0 Blue 12
11 AM Thu 71 74 W 5 2781 3820 0 Blue 17
12 Noon Thu 73 77 W 5 3061 3820 0 Blue 20
1 PM Thu 75 80 W 3 3616 3820 0 Blue 23
2 PM Thu 76 81 W 3 4453 3820 0 Blue 24
3 PM Thu 78 82 W 5 5729 3820 0 Blue 25
4 PM Thu 79 82 W 5 5729 3820 0 Blue 25
5 PM Thu 79 81 W 6 4453 3820 0 Blue 24
6 PM Thu 77 78 W 5 3242 3820 0 Blue 21
7 PM Thu 74 74 W 5 2781 3820 0 Blue 17
8 PM Thu 70 70 W 3 2690 3820 0 Blue 13
9 PM Thu 68 68 W 3 2645 3820 0 Blue 11
10 PM Thu 66 66 W 5 2600 3820 0 Blue 9
11 PM Thu 64 64 W 5 2555 3820 0 Blue 7
12 Midnight Fri 63 63 W 5 2532 3820 0 Blue 6
1 AM Fri 62 62 W 3 2509 3820 0 Blue 5
2 AM Fri 61 61 W 3 2486 3820 0 Blue 4
3 AM Fri 59 59 W 3 2441 3820 0 Blue 2
4 AM Fri 58 58 W 2 2418 3820 0 Blue 1
5 AM Fri 57 57 W 2 2395 3820 0 Blue 0
6 AM Fri 57 57 W 2 2395 3820 0 Blue 0
7 AM Fri 58 58 W 2 2418 3820 0 Blue 1
8 AM Fri 60 60 W 2 2464 3820 0 Blue 3
9 AM Fri 64 64 W 2 2555 3820 0 Blue 7
10 AM Fri 67 68 SW 3 2645 3820 0 Blue 11
11 AM Fri 71 72 SW 3 2736 3820 0 Blue 15
12 Noon Fri 73 74 SW 3 2781 3820 0 Blue 17
1 PM Fri 75 76 SW 5 2880 3820 0 Blue 19
2 PM Fri 77 78 SW 5 3242 3820 0 Blue 21
3 PM Fri 79 80 W 5 3616 3820 0 Blue 23
4 PM Fri 80 81 W 6 4453 3820 0 Blue 24
5 PM Fri 80 81 W 6 4453 3820 0 Blue 24
6 PM Fri 78 78 W 6 3242 3820 0 Blue 21
7 PM Fri 75 75 W 6 2803 3820 0 Blue 18
8 PM Fri 71 71 W 6 2713 3820 0 Blue 14
9 PM Fri 69 69 W 6 2668 3820 0 Blue 12
10 PM Fri 67 67 W 6 2623 3820 0 Blue 10
11 PM Fri 65 65 W 6 2578 3820 0 Blue 8
12 Midnight Sat 64 64 W 6 2555 3820 0 Blue 7
1 AM Sat 63 63 W 6 2532 3820 0 Blue 6
2 AM Sat 62 62 W 6 2509 3820 0 Blue 5
3 AM Sat 61 61 W 6 2486 3820 0 Blue 4
4 AM Sat 59 59 W 6 2441 3820 0 Blue 2
5 AM Sat 58 58 W 5 2418 3820 0 Blue 1
6 AM Sat 58 58 W 5 2418 3820 0 Blue 1
7 AM Sat 59 59 W 5 2441 3820 0 Blue 2
8 AM Sat 61 61 W 5 2486 3820 0 Blue 4
9 AM Sat 64 65 W 5 2578 3820 0 Blue 8
10 AM Sat 68 70 W 5 2690 3820 0 Blue 13
11 AM Sat 71 75 W 7 2803 3820 0 Blue 18
12 Noon Sat 74 78 W 7 3242 3820 0 Blue 21
1 PM Sat 77 82 W 7 5729 3820 0 Blue 25
2 PM Sat 79 84 W 7 7439 4396 576 Blue 27
3 PM Sat 80 84 W 7 7439 4396 576 Blue 27
4 PM Sat 81 84 W 7 7439 4396 576 Blue 27
5 PM Sat 80 81 W 10 4453 3820 0 Blue 24
6 PM Sat 77 77 W 10 3061 3820 0 Blue 20
7 PM Sat 73 73 W 10 2758 3820 0 Blue 16
8 PM Sat 70 70 W 10 2690 3820 0 Blue 13
9 PM Sat 67 67 W 10 2623 3820 0 Blue 10
10 PM Sat 65 65 W 10 2578 3820 0 Blue 8
11 PM Sat 64 64 W 6 2555 3820 0 Blue 7
12 Midnight Sun 62 62 W 6 2509 3820 0 Blue 5
1 AM Sun 61 61 W 6 2486 3820 0 Blue 4
2 AM Sun 59 59 W 6 2441 3820 0 Blue 2
3 AM Sun 58 58 W 6 2418 3820 0 Blue 1
4 AM Sun 58 58 W 6 2418 3820 0 Blue 1
5 AM Sun 57 57 W 3 2395 3820 0 Blue 0
6 AM Sun 57 57 W 3 2395 3820 0 Blue 0
7 AM Sun 58 58 W 3 2418 3820 0 Blue 1
8 AM Sun 60 60 W 3 2464 3820 0 Blue 3
9 AM Sun 64 65 W 3 2578 3820 0 Blue 8
10 AM Sun 68 71 W 3 2713 3820 0 Blue 14
11 AM Sun 72 76 W 6 2880 3820 0 Blue 19
12 Noon Sun 75 80 W 6 3616 3820 0 Blue 23
1 PM Sun 77 83 W 6 7265 3820 0 Blue 26
2 PM Sun 79 84 W 6 7439 4396 576 Blue 27
3 PM Sun 80 84 W 6 7439 4396 576 Blue 27
4 PM Sun 81 84 W 6 7439 4396 576 Blue 27
5 PM Sun 80 82 W 7 5729 3820 0 Blue 25
6 PM Sun 78 79 W 7 3422 3820 0 Blue 22
7 PM Sun 75 75 W 7 2803 3820 0 Blue 18
8 PM Sun 72 72 W 7 2736 3820 0 Blue 15
9 PM Sun 69 69 W 7 2668 3820 0 Blue 12
10 PM Sun 67 67 W 7 2623 3820 0 Blue 10
11 PM Sun 65 65 W 6 2578 3820 0 Blue 8
12 Midnight Mon 63 63 W 6 2532 3820 0 Blue 6
1 AM Mon 61 61 W 6 2486 3820 0 Blue 4
2 AM Mon 60 60 W 6 2464 3820 0 Blue 3
3 AM Mon 59 59 W 6 2441 3820 0 Blue 2
4 AM Mon 58 58 W 6 2418 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