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

Station:

KOTX

Date/Time:

21 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 Wed 63 63 W 8 2406 3820 0 Blue 3
6 AM Wed 63 63 SW 8 2406 3820 0 Blue 3
7 AM Wed 64 64 W 7 2411 3820 0 Blue 4
8 AM Wed 67 67 SW 5 2427 3820 0 Blue 7
9 AM Wed 70 71 W 5 2453 3820 0 Blue 11
10 AM Wed 73 74 W 3 2555 3820 0 Blue 14
11 AM Wed 76 77 W 5 2668 3820 0 Blue 17
12 Noon Wed 79 80 W 6 2809 3820 0 Blue 20
1 PM Wed 80 81 W 12 2857 3820 0 Blue 21
2 PM Wed 80 80 SW 10 2809 3820 0 Blue 20
3 PM Wed 79 79 SW 17 2760 3820 0 Blue 19
4 PM Wed 77 77 S 13 2668 3820 0 Blue 17
5 PM Wed 75 75 S 14 2593 3820 0 Blue 15
6 PM Wed 71 71 SW 16 2453 3820 0 Blue 11
7 PM Wed 69 69 SW 15 2438 3820 0 Blue 9
8 PM Wed 66 66 SW 12 2422 3820 0 Blue 6
9 PM Wed 65 65 SW 10 2417 3820 0 Blue 5
10 PM Wed 64 64 SW 9 2411 3820 0 Blue 4
11 PM Wed 64 64 W 9 2411 3820 0 Blue 4
12 Midnight Thu 62 62 SW 8 2401 3820 0 Blue 2
1 AM Thu 61 61 SW 9 2396 3820 0 Blue 1
2 AM Thu 59 59 SW 8 0 3820 0 Blue 0
3 AM Thu 59 59 SW 8 0 3820 0 Blue 0
4 AM Thu 58 58 W 7 0 3820 0 Blue 0
5 AM Thu 58 58 W 5 0 3820 0 Blue 0
6 AM Thu 58 58 W 5 0 3820 0 Blue 0
7 AM Thu 59 59 W 5 0 3820 0 Blue 0
8 AM Thu 60 60 W 5 2390 3820 0 Blue 0
9 AM Thu 63 64 W 3 2411 3820 0 Blue 4
10 AM Thu 67 70 W 3 2443 3820 0 Blue 10
11 AM Thu 70 74 W 3 2555 3820 0 Blue 14
12 Noon Thu 72 77 W 3 2668 3820 0 Blue 17
1 PM Thu 74 80 NW 3 2809 3820 0 Blue 20
2 PM Thu 76 81 NW 3 2857 3820 0 Blue 21
3 PM Thu 77 81 W 2 2857 3820 0 Blue 21
4 PM Thu 79 82 W 3 2929 3820 0 Blue 22
5 PM Thu 79 81 SW 3 2857 3820 0 Blue 21
6 PM Thu 77 78 SW 3 2712 3820 0 Blue 18
7 PM Thu 74 74 W 3 2555 3820 0 Blue 14
8 PM Thu 71 71 W 3 2453 3820 0 Blue 11
9 PM Thu 68 68 W 3 2433 3820 0 Blue 8
10 PM Thu 67 67 W 5 2427 3820 0 Blue 7
11 PM Thu 65 65 W 5 2417 3820 0 Blue 5
12 Midnight Fri 63 63 W 3 2406 3820 0 Blue 3
1 AM Fri 62 62 W 3 2401 3820 0 Blue 2
2 AM Fri 60 60 W 2 2390 3820 0 Blue 0
3 AM Fri 59 59 W 2 0 3820 0 Blue 0
4 AM Fri 58 58 W 2 0 3820 0 Blue 0
5 AM Fri 58 58 W 2 0 3820 0 Blue 0
6 AM Fri 58 58 W 2 0 3820 0 Blue 0
7 AM Fri 59 59 W 1 0 3820 0 Blue 0
8 AM Fri 61 61 W 1 2396 3820 0 Blue 1
9 AM Fri 64 64 W 2 2411 3820 0 Blue 4
10 AM Fri 68 68 SW 2 2433 3820 0 Blue 8
11 AM Fri 71 72 SW 3 2486 3820 0 Blue 12
12 Noon Fri 73 74 SW 3 2555 3820 0 Blue 14
1 PM Fri 75 77 SW 3 2668 3820 0 Blue 17
2 PM Fri 77 79 SW 3 2760 3820 0 Blue 19
3 PM Fri 78 80 SW 5 2809 3820 0 Blue 20
4 PM Fri 80 81 W 5 2857 3820 0 Blue 21
5 PM Fri 80 81 W 6 2857 3820 0 Blue 21
6 PM Fri 78 78 W 6 2712 3820 0 Blue 18
7 PM Fri 75 75 W 6 2593 3820 0 Blue 15
8 PM Fri 72 72 W 6 2486 3820 0 Blue 12
9 PM Fri 70 70 W 6 2443 3820 0 Blue 10
10 PM Fri 68 68 W 6 2433 3820 0 Blue 8
11 PM Fri 66 66 W 6 2422 3820 0 Blue 6
12 Midnight Sat 65 65 W 6 2417 3820 0 Blue 5
1 AM Sat 64 64 W 6 2411 3820 0 Blue 4
2 AM Sat 63 63 W 6 2406 3820 0 Blue 3
3 AM Sat 61 61 W 6 2396 3820 0 Blue 1
4 AM Sat 60 60 W 5 2390 3820 0 Blue 0
5 AM Sat 58 58 W 5 0 3820 0 Blue 0
6 AM Sat 58 58 W 5 0 3820 0 Blue 0
7 AM Sat 59 59 W 3 0 3820 0 Blue 0
8 AM Sat 61 61 W 3 2396 3820 0 Blue 1
9 AM Sat 64 65 W 3 2417 3820 0 Blue 5
10 AM Sat 67 69 W 5 2438 3820 0 Blue 9
11 AM Sat 71 74 W 6 2555 3820 0 Blue 14
12 Noon Sat 74 78 W 7 2712 3820 0 Blue 18
1 PM Sat 76 81 W 9 2857 3820 0 Blue 21
2 PM Sat 78 83 W 12 3175 3820 0 Blue 23
3 PM Sat 79 83 W 14 3175 3820 0 Blue 23
4 PM Sat 80 83 W 16 3175 3820 0 Blue 23
5 PM Sat 79 81 W 17 2857 3820 0 Blue 21
6 PM Sat 77 77 W 17 2668 3820 0 Blue 17
7 PM Sat 73 73 W 17 2519 3820 0 Blue 13
8 PM Sat 69 69 W 17 2438 3820 0 Blue 9
9 PM Sat 67 67 W 17 2427 3820 0 Blue 7
10 PM Sat 65 65 W 17 2417 3820 0 Blue 5
11 PM Sat 63 63 W 7 2406 3820 0 Blue 3
12 Midnight Sun 62 62 W 7 2401 3820 0 Blue 2
1 AM Sun 60 60 W 7 2390 3820 0 Blue 0
2 AM Sun 59 59 W 7 0 3820 0 Blue 0
3 AM Sun 57 57 W 7 0 3820 0 Blue 0
4 AM Sun 57 57 W 7 0 3820 0 Blue 0
5 AM Sun 56 56 W 5 0 3820 0 Blue 0
6 AM Sun 56 56 W 5 0 3820 0 Blue 0
7 AM Sun 57 57 W 5 0 3820 0 Blue 0
8 AM Sun 59 59 W 5 0 3820 0 Blue 0
9 AM Sun 62 63 W 5 2406 3820 0 Blue 3
10 AM Sun 66 69 W 5 2438 3820 0 Blue 9
11 AM Sun 70 74 W 8 2555 3820 0 Blue 14
12 Noon Sun 73 78 W 8 2712 3820 0 Blue 18
1 PM Sun 75 81 W 8 2857 3820 0 Blue 21
2 PM Sun 77 82 W 8 2929 3820 0 Blue 22
3 PM Sun 78 83 W 8 3175 3820 0 Blue 23
4 PM Sun 78 81 W 8 2857 3820 0 Blue 21
5 PM Sun 77 79 W 17 2760 3820 0 Blue 19
6 PM Sun 75 76 W 17 2630 3820 0 Blue 16
7 PM Sun 72 72 W 17 2486 3820 0 Blue 12
8 PM Sun 68 68 W 17 2433 3820 0 Blue 8
9 PM Sun 66 66 W 17 2422 3820 0 Blue 6
10 PM Sun 64 64 W 17 2411 3820 0 Blue 4
11 PM Sun 62 62 W 6 2401 3820 0 Blue 2
12 Midnight Mon 61 61 W 6 2396 3820 0 Blue 1
1 AM Mon 59 59 W 6 0 3820 0 Blue 0
2 AM Mon 58 58 W 6 0 3820 0 Blue 0
3 AM Mon 56 56 W 6 0 3820 0 Blue 0
4 AM Mon 56 56 W 6 0 3820 0 Blue 0
5 AM Mon 55 55 W 3 0 3820 0 Blue 0
6 AM Mon 55 55 W 3 0 3820 0 Blue 0
7 AM Mon 56 56 W 3 0 3820 0 Blue 0
8 AM Mon 58 58 W 3 0 3820 0 Blue 0
9 AM Mon 61 63 W 3 2406 3820 0 Blue 3
10 AM Mon 66 69 W 3 2438 3820 0 Blue 9
11 AM Mon 70 74 NW 3 2555 3820 0 Blue 14
12 Noon Mon 74 79 NW 3 2760 3820 0 Blue 19
1 PM Mon 77 83 NW 3 3175 3820 0 Blue 23
2 PM Mon 79 85 NW 3 3962 3820 0 Blue 25
3 PM Mon 80 85 NW 3 3962 3820 0 Blue 25
4 PM Mon 81 84 NW 3 3435 3820 0 Blue 24
5 PM Mon 80 82 NW 5 2929 3820 0 Blue 22
6 PM Mon 78 79 NW 5 2760 3820 0 Blue 19
7 PM Mon 75 75 NW 5 2593 3820 0 Blue 15
8 PM Mon 72 72 NW 5 2486 3820 0 Blue 12
9 PM Mon 69 69 NW 5 2438 3820 0 Blue 9
10 PM Mon 67 67 NW 5 2427 3820 0 Blue 7
11 PM Mon 66 66 N 6 2422 3820 0 Blue 6
12 Midnight Tue 64 64 N 6 2411 3820 0 Blue 4
1 AM Tue 62 62 N 6 2401 3820 0 Blue 2
2 AM Tue 61 61 N 6 2396 3820 0 Blue 1
3 AM Tue 59 59 N 6 0 3820 0 Blue 0
4 AM Tue 58 58 N 6 0 3820 0 Blue 0

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