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

Station:

 KOTX

Date/Time:

 3 SEP 2010

Temp/Wind data from:

NOAA Digital Forecast

Time
(Local)		 High
Temp
Puddle
Temp
Wind
 (mph)		 Thermal
Ceiling
(ft)		 Soaring
Ceiling
(ft)		 Above
Launch
(ft)		 Thermal
Type		 Thermal
Index
(F)
5 AM Fri 53 53 NW 2 2430 3820 0 Blue 3
6 AM Fri 51 51 NW 2 2399 3820 0 Blue 1
7 AM Fri 53 53 NW 2 2430 3820 0 Blue 3
8 AM Fri 62 62 N 1 3069 3820 0 Blue 12
9 AM Fri 68 69 N 1 3481 3820 0 Blue 19
10 AM Fri 73 75 N 1 4421 3820 0 Blue 25
11 AM Fri 78 81 SW 1 6383 5649 1829 Blue 31
12 Noon Fri 82 86 SW 1 7864 6753 2933 Blue 36
1 PM Fri 84 88 SW 1 9452 7455 3635 Blue 38
2 PM Fri 86 90 S 7 10155 8137 4317 Blue 40
3 PM Fri 87 90 S 7 10155 8137 4317 Blue 40
4 PM Fri 86 88 S 7 9452 7455 3635 Blue 38
5 PM Fri 86 87 SW 8 8201 7106 3286 Blue 37
6 PM Fri 85 85 SW 8 7515 6473 2653 Blue 35
7 PM Fri 80 80 SW 8 6260 5070 1250 Blue 30
8 PM Fri 75 75 W 10 4421 3820 0 Blue 25
9 PM Fri 71 71 W 10 3662 3820 0 Blue 21
10 PM Fri 68 68 W 10 3390 3820 0 Blue 18
11 PM Fri 66 66 W 12 3246 3820 0 Blue 16
12 Midnight Sat 64 64 W 12 3157 3820 0 Blue 14
1 AM Sat 61 61 W 12 2915 3820 0 Blue 11
2 AM Sat 60 60 W 9 2760 3820 0 Blue 10
3 AM Sat 60 60 W 9 2760 3820 0 Blue 10
4 AM Sat 58 58 W 9 2548 3820 0 Blue 8
5 AM Sat 57 57 W 9 2509 3820 0 Blue 7
6 AM Sat 54 54 W 9 2445 3820 0 Blue 4
7 AM Sat 55 55 W 9 2460 3820 0 Blue 5
8 AM Sat 60 60 W 10 2760 3820 0 Blue 10
9 AM Sat 63 64 W 10 3157 3820 0 Blue 14
10 AM Sat 65 67 W 10 3299 3820 0 Blue 17
11 AM Sat 67 70 W 21 3571 3820 0 Blue 20
12 Noon Sat 69 73 W 21 3964 3820 0 Blue 23
1 PM Sat 71 75 W 21 4421 3820 0 Blue 25
2 PM Sat 72 76 W 21 4754 3954 134 Blue 26
3 PM Sat 72 75 W 21 4421 3820 0 Blue 25
4 PM Sat 71 73 W 21 3964 3820 0 Blue 23
5 PM Sat 71 72 W 21 3806 3820 0 Blue 22
6 PM Sat 71 71 W 21 3662 3820 0 Blue 21
7 PM Sat 67 67 W 21 3299 3820 0 Blue 17
8 PM Sat 62 62 W 21 3069 3820 0 Blue 12
9 PM Sat 59 59 W 21 2625 3820 0 Blue 9
10 PM Sat 56 56 W 21 2475 3820 0 Blue 6
11 PM Sat 55 55 W 10 2460 3820 0 Blue 5
12 Midnight Sun 53 53 W 10 2430 3820 0 Blue 3
1 AM Sun 51 51 W 10 2399 3820 0 Blue 1
2 AM Sun 50 50 W 10 0 3820 0 Blue 0
3 AM Sun 50 50 W 10 0 3820 0 Blue 0
4 AM Sun 48 48 W 10 0 3820 0 Blue 0
5 AM Sun 47 47 W 6 0 3820 0 Blue 0
6 AM Sun 45 45 W 6 0 3820 0 Blue 0
7 AM Sun 47 47 W 6 0 3820 0 Blue 0
8 AM Sun 52 52 W 6 2414 3820 0 Blue 2
9 AM Sun 56 56 W 6 2475 3820 0 Blue 6
10 AM Sun 58 59 W 6 2625 3820 0 Blue 9
11 AM Sun 61 62 W 9 3069 3820 0 Blue 12
12 Noon Sun 64 66 W 9 3246 3820 0 Blue 16
1 PM Sun 65 67 W 9 3299 3820 0 Blue 17
2 PM Sun 66 68 W 9 3390 3820 0 Blue 18
3 PM Sun 67 69 W 9 3481 3820 0 Blue 19
4 PM Sun 67 68 W 9 3390 3820 0 Blue 18
5 PM Sun 66 66 W 15 3246 3820 0 Blue 16
6 PM Sun 66 66 W 15 3246 3820 0 Blue 16
7 PM Sun 62 62 W 15 3069 3820 0 Blue 12
8 PM Sun 58 58 W 15 2548 3820 0 Blue 8
9 PM Sun 56 56 W 15 2475 3820 0 Blue 6
10 PM Sun 54 54 W 15 2445 3820 0 Blue 4
11 PM Sun 52 52 W 8 2414 3820 0 Blue 2
12 Midnight Mon 51 51 W 8 2399 3820 0 Blue 1
1 AM Mon 49 49 W 8 0 3820 0 Blue 0
2 AM Mon 48 48 W 8 0 3820 0 Blue 0
3 AM Mon 48 48 W 8 0 3820 0 Blue 0
4 AM Mon 47 47 W 8 0 3820 0 Blue 0
5 AM Mon 46 46 W 6 0 3820 0 Blue 0
6 AM Mon 44 44 W 6 0 3820 0 Blue 0
7 AM Mon 46 46 W 6 0 3820 0 Blue 0
8 AM Mon 53 53 W 6 2430 3820 0 Blue 3
9 AM Mon 57 57 W 6 2509 3820 0 Blue 7
10 AM Mon 61 62 W 6 3069 3820 0 Blue 12
11 AM Mon 65 66 S 5 3246 3820 0 Blue 16
12 Noon Mon 68 70 S 5 3571 3820 0 Blue 20
1 PM Mon 70 72 S 5 3806 3820 0 Blue 22
2 PM Mon 71 73 S 5 3964 3820 0 Blue 23
3 PM Mon 72 74 S 5 4122 3820 0 Blue 24
4 PM Mon 71 72 S 5 3806 3820 0 Blue 22
5 PM Mon 71 71 S 6 3662 3820 0 Blue 21
6 PM Mon 71 71 S 6 3662 3820 0 Blue 21
7 PM Mon 67 67 S 6 3299 3820 0 Blue 17
8 PM Mon 62 62 S 6 3069 3820 0 Blue 12
9 PM Mon 59 59 S 6 2625 3820 0 Blue 9
10 PM Mon 56 56 S 6 2475 3820 0 Blue 6
11 PM Mon 55 55 SE 2 2460 3820 0 Blue 5
12 Midnight Tue 53 53 SE 2 2430 3820 0 Blue 3
1 AM Tue 51 51 SE 2 2399 3820 0 Blue 1
2 AM Tue 50 50 SE 2 0 3820 0 Blue 0
3 AM Tue 50 50 SE 2 0 3820 0 Blue 0
4 AM Tue 48 48 SE 2 0 3820 0 Blue 0
5 AM Tue 47 47 N 5 0 3820 0 Blue 0
6 AM Tue 45 45 N 5 0 3820 0 Blue 0
7 AM Tue 47 47 N 5 0 3820 0 Blue 0
8 AM Tue 53 53 N 5 2430 3820 0 Blue 3
9 AM Tue 58 58 N 5 2548 3820 0 Blue 8
10 AM Tue 61 62 N 5 3069 3820 0 Blue 12
11 AM Tue 65 66 E 3 3246 3820 0 Blue 16
12 Noon Tue 68 70 E 3 3571 3820 0 Blue 20
1 PM Tue 70 72 E 3 3806 3820 0 Blue 22
2 PM Tue 71 73 E 3 3964 3820 0 Blue 23
3 PM Tue 72 73 E 3 3964 3820 0 Blue 23
4 PM Tue 71 72 E 3 3806 3820 0 Blue 22
5 PM Tue 71 71 NE 7 3662 3820 0 Blue 21
6 PM Tue 71 71 NE 7 3662 3820 0 Blue 21
7 PM Tue 67 67 NE 7 3299 3820 0 Blue 17
8 PM Tue 62 62 NE 7 3069 3820 0 Blue 12
9 PM Tue 59 59 NE 7 2625 3820 0 Blue 9
10 PM Tue 56 56 NE 7 2475 3820 0 Blue 6
11 PM Tue 55 55 NW 8 2460 3820 0 Blue 5
12 Midnight Wed 53 53 NW 8 2430 3820 0 Blue 3
1 AM Wed 51 51 NW 8 2399 3820 0 Blue 1
2 AM Wed 50 50 NW 8 0 3820 0 Blue 0
3 AM Wed 50 50 NW 8 0 3820 0 Blue 0
4 AM Wed 48 48 NW 8 0 3820 0 Blue 0
5 AM Wed 47 47 NW 7 0 3820 0 Blue 0
6 AM Wed 45 45 NW 7 0 3820 0 Blue 0
7 AM Wed 47 47 NW 7 0 3820 0 Blue 0
8 AM Wed 54 54 NW 7 2445 3820 0 Blue 4
9 AM Wed 59 59 NW 7 2625 3820 0 Blue 9
10 AM Wed 63 64 NW 7 3157 3820 0 Blue 14
11 AM Wed 67 69 N 5 3481 3820 0 Blue 19
12 Noon Wed 71 73 N 5 3964 3820 0 Blue 23
1 PM Wed 73 76 N 5 4754 3954 134 Blue 26
2 PM Wed 74 76 N 5 4754 3954 134 Blue 26
3 PM Wed 75 77 N 5 5127 4111 291 Blue 27
4 PM Wed 74 75 N 5 4421 3820 0 Blue 25
5 PM Wed 74 75 W 5 4421 3820 0 Blue 25
6 PM Wed 73 73 W 5 3964 3820 0 Blue 23
7 PM Wed 69 69 W 5 3481 3820 0 Blue 19
8 PM Wed 64 64 W 5 3157 3820 0 Blue 14
9 PM Wed 60 60 W 5 2760 3820 0 Blue 10
10 PM Wed 57 57 W 5 2509 3820 0 Blue 7
11 PM Wed 55 55 W 7 2460 3820 0 Blue 5
12 Midnight Thu 53 53 W 7 2430 3820 0 Blue 3
1 AM Thu 51 51 W 7 2399 3820 0 Blue 1
2 AM Thu 50 50 W 7 0 3820 0 Blue 0
3 AM Thu 49 49 W 7 0 3820 0 Blue 0
4 AM Thu 48 48 W 7 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