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

Station:

KOTX

Date/Time:

25 SEP 2017

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 Mon 52 52 W 5 0 3820 0 Blue 0
6 AM Mon 51 51 W 5 0 3820 0 Blue 0
7 AM Mon 51 51 W 5 0 3820 0 Blue 0
8 AM Mon 52 52 NW 3 0 3820 0 Blue 0
9 AM Mon 55 55 NW 3 0 3820 0 Blue 0
10 AM Mon 59 59 NW 3 0 3820 0 Blue 0
11 AM Mon 62 63 W 2 0 3820 0 Blue 0
12 Noon Mon 65 66 W 2 0 3820 0 Blue 0
1 PM Mon 67 68 W 2 8263 4885 1065 White 3
2 PM Mon 68 69 SW 5 8475 7999 4179 White 4
3 PM Mon 69 70 SW 5 8684 8657 4837 White 5
4 PM Mon 70 71 SW 5 8891 8857 5037 White 6
5 PM Mon 69 69 W 6 8475 7999 4179 White 4
6 PM Mon 67 67 W 6 8050 3820 0 White 2
7 PM Mon 63 63 W 6 0 3820 0 Blue 0
8 PM Mon 60 60 NW 6 0 3820 0 Blue 0
9 PM Mon 57 57 NW 6 0 3820 0 Blue 0
10 PM Mon 55 55 NW 6 0 3820 0 Blue 0
11 PM Mon 53 53 NW 6 0 3820 0 Blue 0
12 Midnight Tue 52 52 NW 6 0 3820 0 Blue 0
1 AM Tue 51 51 NW 6 0 3820 0 Blue 0
2 AM Tue 50 50 NW 6 0 3820 0 Blue 0
3 AM Tue 50 50 NW 6 0 3820 0 Blue 0
4 AM Tue 49 49 NW 6 0 3820 0 Blue 0
5 AM Tue 49 49 NW 6 0 3820 0 Blue 0
6 AM Tue 48 48 NW 6 0 3820 0 Blue 0
7 AM Tue 48 48 NW 6 0 3820 0 Blue 0
8 AM Tue 50 50 E 5 0 3820 0 Blue 0
9 AM Tue 54 54 E 5 0 3820 0 Blue 0
10 AM Tue 59 60 E 5 0 3820 0 Blue 0
11 AM Tue 65 67 E 3 8050 3820 0 White 2
12 Noon Tue 68 70 E 3 8684 8657 4837 White 5
1 PM Tue 70 73 E 3 9305 9190 5370 White 8
2 PM Tue 72 74 E 3 9513 9342 5522 White 9
3 PM Tue 73 75 E 3 9726 9495 5675 White 10
4 PM Tue 73 74 E 3 9513 9342 5522 White 9
5 PM Tue 72 72 NE 3 9098 9037 5217 White 7
6 PM Tue 69 69 NE 3 8475 7999 4179 White 4
7 PM Tue 65 65 NE 3 0 3820 0 Blue 0
8 PM Tue 62 62 W 5 0 3820 0 Blue 0
9 PM Tue 59 59 W 5 0 3820 0 Blue 0
10 PM Tue 57 57 W 5 0 3820 0 Blue 0
11 PM Tue 56 56 N 6 0 3820 0 Blue 0
12 Midnight Wed 55 55 N 6 0 3820 0 Blue 0
1 AM Wed 54 54 N 6 0 3820 0 Blue 0
2 AM Wed 53 53 N 5 0 3820 0 Blue 0
3 AM Wed 52 52 N 5 0 3820 0 Blue 0
4 AM Wed 52 52 N 5 0 3820 0 Blue 0
5 AM Wed 51 51 NW 6 0 3820 0 Blue 0
6 AM Wed 50 50 NW 6 0 3820 0 Blue 0
7 AM Wed 50 50 NW 6 0 3820 0 Blue 0
8 AM Wed 52 52 N 5 0 3820 0 Blue 0
9 AM Wed 56 57 N 5 0 3820 0 Blue 0
10 AM Wed 61 63 N 5 0 3820 0 Blue 0
11 AM Wed 65 68 E 3 8263 4885 1065 White 3
12 Noon Wed 69 72 E 3 9098 9037 5217 White 7
1 PM Wed 72 76 E 3 9941 9941 6121 White 11
2 PM Wed 74 77 E 6 10155 10155 6335 White 12
3 PM Wed 75 78 E 6 10360 10360 6540 White 13
4 PM Wed 76 78 E 6 10360 10360 6540 White 13
5 PM Wed 75 75 NE 3 9726 9495 5675 White 10
6 PM Wed 72 72 NE 3 9098 9037 5217 White 7
7 PM Wed 69 69 NE 3 8475 7999 4179 White 4
8 PM Wed 65 65 N 5 0 3820 0 Blue 0
9 PM Wed 62 62 N 5 0 3820 0 Blue 0
10 PM Wed 60 60 N 5 0 3820 0 Blue 0
11 PM Wed 59 59 N 6 0 3820 0 Blue 0
12 Midnight Thu 57 57 N 6 0 3820 0 Blue 0
1 AM Thu 56 56 N 6 0 3820 0 Blue 0
2 AM Thu 55 55 N 6 0 3820 0 Blue 0
3 AM Thu 54 54 N 6 0 3820 0 Blue 0
4 AM Thu 53 53 N 6 0 3820 0 Blue 0
5 AM Thu 52 52 N 5 0 3820 0 Blue 0
6 AM Thu 51 51 N 5 0 3820 0 Blue 0
7 AM Thu 51 51 N 5 0 3820 0 Blue 0
8 AM Thu 52 52 N 5 0 3820 0 Blue 0
9 AM Thu 56 57 N 5 0 3820 0 Blue 0
10 AM Thu 61 63 N 5 0 3820 0 Blue 0
11 AM Thu 66 69 SE 6 8475 7999 4179 White 4
12 Noon Thu 70 73 SE 6 9305 9190 5370 White 8
1 PM Thu 73 77 SE 6 10155 10155 6335 White 12
2 PM Thu 76 79 SE 6 10564 10564 6744 White 14
3 PM Thu 77 80 SE 6 10768 10768 6948 White 15
4 PM Thu 78 80 SE 6 10768 10768 6948 White 15
5 PM Thu 77 77 NW 3 10155 10155 6335 White 12
6 PM Thu 74 74 NW 3 9513 9342 5522 White 9
7 PM Thu 69 69 NW 3 8475 7999 4179 White 4
8 PM Thu 65 65 NW 3 0 3820 0 Blue 0
9 PM Thu 62 62 NW 3 0 3820 0 Blue 0
10 PM Thu 60 60 NW 3 0 3820 0 Blue 0
11 PM Thu 59 59 NW 5 0 3820 0 Blue 0
12 Midnight Fri 57 57 NW 5 0 3820 0 Blue 0
1 AM Fri 56 56 NW 5 0 3820 0 Blue 0
2 AM Fri 55 55 NW 5 0 3820 0 Blue 0
3 AM Fri 54 54 NW 5 0 3820 0 Blue 0
4 AM Fri 53 53 NW 5 0 3820 0 Blue 0
5 AM Fri 52 52 NW 3 0 3820 0 Blue 0
6 AM Fri 51 51 NW 3 0 3820 0 Blue 0
7 AM Fri 51 51 NW 3 0 3820 0 Blue 0
8 AM Fri 52 52 NW 3 0 3820 0 Blue 0
9 AM Fri 56 56 NW 3 0 3820 0 Blue 0
10 AM Fri 61 63 NW 3 0 3820 0 Blue 0
11 AM Fri 65 66 S 6 0 3820 0 Blue 0
12 Noon Fri 70 71 S 6 8891 8857 5037 White 6
1 PM Fri 73 75 S 6 9726 9495 5675 White 10
2 PM Fri 75 76 S 6 9941 9941 6121 White 11
3 PM Fri 76 77 S 6 10155 10155 6335 White 12
4 PM Fri 76 77 S 6 10155 10155 6335 White 12
5 PM Fri 75 75 SW 8 9726 9495 5675 White 10
6 PM Fri 72 72 SW 8 9098 9037 5217 White 7
7 PM Fri 68 68 SW 8 8263 4885 1065 White 3
8 PM Fri 65 65 SW 8 0 3820 0 Blue 0
9 PM Fri 62 62 SW 8 0 3820 0 Blue 0
10 PM Fri 61 61 SW 8 0 3820 0 Blue 0
11 PM Fri 59 59 W 10 0 3820 0 Blue 0
12 Midnight Sat 58 58 W 10 0 3820 0 Blue 0
1 AM Sat 56 56 W 10 0 3820 0 Blue 0
2 AM Sat 55 55 W 10 0 3820 0 Blue 0
3 AM Sat 54 54 W 10 0 3820 0 Blue 0
4 AM Sat 53 53 W 10 0 3820 0 Blue 0
5 AM Sat 52 52 W 10 0 3820 0 Blue 0
6 AM Sat 51 51 W 10 0 3820 0 Blue 0
7 AM Sat 51 51 W 10 0 3820 0 Blue 0
8 AM Sat 52 52 W 10 0 3820 0 Blue 0
9 AM Sat 55 55 W 10 0 3820 0 Blue 0
10 AM Sat 59 60 W 10 0 3820 0 Blue 0
11 AM Sat 63 65 W 13 0 3820 0 Blue 0
12 Noon Sat 66 69 W 13 8475 7999 4179 White 4
1 PM Sat 69 72 W 13 9098 9037 5217 White 7
2 PM Sat 71 74 W 13 9513 9342 5522 White 9
3 PM Sat 72 74 W 13 9513 9342 5522 White 9
4 PM Sat 72 73 W 13 9305 9190 5370 White 8
5 PM Sat 71 71 W 13 8891 8857 5037 White 6
6 PM Sat 67 67 W 13 8050 3820 0 White 2
7 PM Sat 63 63 W 13 0 3820 0 Blue 0
8 PM Sat 59 59 W 13 0 3820 0 Blue 0
9 PM Sat 56 56 W 13 0 3820 0 Blue 0
10 PM Sat 54 54 W 13 0 3820 0 Blue 0
11 PM Sat 53 53 W 9 0 3820 0 Blue 0
12 Midnight Sun 51 51 W 9 0 3820 0 Blue 0
1 AM Sun 49 49 W 9 0 3820 0 Blue 0
2 AM Sun 48 48 W 9 0 3820 0 Blue 0
3 AM Sun 47 47 W 9 0 3820 0 Blue 0
4 AM Sun 46 46 W 9 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