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

Station:

KOTX

Date/Time:

26 APR 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 Thu 48 48 N 5 2460 3820 0 Blue 9
6 AM Thu 51 51 N 5 2495 3820 0 Blue 12
7 AM Thu 52 52 N 5 2512 3820 0 Blue 13
8 AM Thu 54 55 N 5 2612 3820 0 Blue 16
9 AM Thu 57 59 N 5 2881 3820 0 Blue 20
10 AM Thu 60 64 NE 5 3592 3820 0 Blue 25
11 AM Thu 63 68 NE 5 4030 3820 0 Blue 29
12 Noon Thu 65 71 NE 6 6335 4012 192 Blue 32
1 PM Thu 67 73 E 6 7698 4672 852 Blue 34
2 PM Thu 68 74 E 6 7760 6098 2278 Blue 35
3 PM Thu 69 74 E 6 7760 6098 2278 Blue 35
4 PM Thu 70 73 E 6 7698 4672 852 Blue 34
5 PM Thu 70 72 E 6 7572 4295 475 Blue 33
6 PM Thu 68 68 E 6 4030 3820 0 Blue 29
7 PM Thu 64 64 NE 5 3592 3820 0 Blue 25
8 PM Thu 61 61 NE 5 3279 3820 0 Blue 22
9 PM Thu 57 57 NE 5 2769 3820 0 Blue 18
10 PM Thu 54 54 N 5 2566 3820 0 Blue 15
11 PM Thu 52 52 N 5 2512 3820 0 Blue 13
12 Midnight Fri 50 50 N 5 2479 3820 0 Blue 11
1 AM Fri 49 49 N 6 2468 3820 0 Blue 10
2 AM Fri 48 48 N 6 2460 3820 0 Blue 9
3 AM Fri 47 47 N 6 2452 3820 0 Blue 8
4 AM Fri 46 46 NW 6 2444 3820 0 Blue 7
5 AM Fri 45 45 NW 6 2436 3820 0 Blue 6
6 AM Fri 46 46 N 6 2444 3820 0 Blue 7
7 AM Fri 47 47 N 6 2452 3820 0 Blue 8
8 AM Fri 50 51 N 6 2495 3820 0 Blue 12
9 AM Fri 54 56 N 6 2710 3820 0 Blue 17
10 AM Fri 59 62 N 6 3386 3820 0 Blue 23
11 AM Fri 63 68 N 6 4030 3820 0 Blue 29
12 Noon Fri 67 72 N 6 7572 4295 475 Blue 33
1 PM Fri 69 75 NE 6 7812 7549 3729 Blue 36
2 PM Fri 71 76 NE 6 7863 7675 3855 Blue 37
3 PM Fri 72 76 NE 5 7863 7675 3855 Blue 37
4 PM Fri 72 74 NE 3 7760 6098 2278 Blue 35
5 PM Fri 71 72 NE 3 7572 4295 475 Blue 33
6 PM Fri 69 69 N 3 4315 3820 0 Blue 30
7 PM Fri 65 65 NW 5 3695 3820 0 Blue 26
8 PM Fri 63 63 W 6 3489 3820 0 Blue 24
9 PM Fri 60 60 W 7 2937 3820 0 Blue 21
10 PM Fri 59 59 W 8 2881 3820 0 Blue 20
11 PM Fri 57 57 W 9 2769 3820 0 Blue 18
12 Midnight Sat 56 56 W 10 2710 3820 0 Blue 17
1 AM Sat 55 55 W 10 2612 3820 0 Blue 16
2 AM Sat 54 54 W 10 2566 3820 0 Blue 15
3 AM Sat 54 54 W 10 2566 3820 0 Blue 15
4 AM Sat 53 53 W 10 2528 3820 0 Blue 14
5 AM Sat 52 52 W 9 2512 3820 0 Blue 13
6 AM Sat 51 51 W 8 2495 3820 0 Blue 12
7 AM Sat 50 50 W 6 2479 3820 0 Blue 11
8 AM Sat 49 49 W 5 2468 3820 0 Blue 10
9 AM Sat 49 49 W 5 2468 3820 0 Blue 10
10 AM Sat 50 50 W 5 2479 3820 0 Blue 11
11 AM Sat 52 52 W 5 2512 3820 0 Blue 13
12 Noon Sat 53 53 W 5 2528 3820 0 Blue 14
1 PM Sat 54 54 W 6 2566 3820 0 Blue 15
2 PM Sat 55 55 SW 6 2612 3820 0 Blue 16
3 PM Sat 56 56 SW 6 2710 3820 0 Blue 17
4 PM Sat 56 56 SW 7 2710 3820 0 Blue 17
5 PM Sat 55 55 W 7 2612 3820 0 Blue 16
6 PM Sat 54 54 W 7 2566 3820 0 Blue 15
7 PM Sat 52 52 W 6 2512 3820 0 Blue 13
8 PM Sat 51 51 W 6 2495 3820 0 Blue 12
9 PM Sat 49 49 W 6 2468 3820 0 Blue 10
10 PM Sat 47 47 W 6 2452 3820 0 Blue 8
11 PM Sat 46 46 W 6 2444 3820 0 Blue 7
12 Midnight Sun 45 45 W 6 2436 3820 0 Blue 6
1 AM Sun 44 44 W 6 2428 3820 0 Blue 5
2 AM Sun 43 43 W 6 2420 3820 0 Blue 4
3 AM Sun 43 43 W 6 2420 3820 0 Blue 4
4 AM Sun 42 42 W 6 2412 3820 0 Blue 3
5 AM Sun 42 42 W 6 2412 3820 0 Blue 3
6 AM Sun 42 42 W 6 2412 3820 0 Blue 3
7 AM Sun 43 43 W 6 2420 3820 0 Blue 4
8 AM Sun 45 45 W 6 2436 3820 0 Blue 6
9 AM Sun 46 46 W 7 2444 3820 0 Blue 7
10 AM Sun 48 48 W 7 2460 3820 0 Blue 9
11 AM Sun 50 50 W 7 2479 3820 0 Blue 11
12 Noon Sun 51 51 W 7 2495 3820 0 Blue 12
1 PM Sun 52 52 W 8 2512 3820 0 Blue 13
2 PM Sun 53 53 W 8 2528 3820 0 Blue 14
3 PM Sun 54 54 W 9 2566 3820 0 Blue 15
4 PM Sun 54 54 W 9 2566 3820 0 Blue 15
5 PM Sun 53 53 W 8 2528 3820 0 Blue 14
6 PM Sun 52 52 W 8 2512 3820 0 Blue 13
7 PM Sun 50 50 W 8 2479 3820 0 Blue 11
8 PM Sun 48 48 W 8 2460 3820 0 Blue 9
9 PM Sun 46 46 W 8 2444 3820 0 Blue 7
10 PM Sun 45 45 W 8 2436 3820 0 Blue 6
11 PM Sun 44 44 W 5 2428 3820 0 Blue 5
12 Midnight Mon 44 44 W 5 2428 3820 0 Blue 5
1 AM Mon 44 44 W 5 2428 3820 0 Blue 5
2 AM Mon 43 43 W 5 2420 3820 0 Blue 4
3 AM Mon 42 42 W 5 2412 3820 0 Blue 3
4 AM Mon 41 41 W 5 2404 3820 0 Blue 2
5 AM Mon 41 41 W 6 2404 3820 0 Blue 2
6 AM Mon 41 41 W 6 2404 3820 0 Blue 2
7 AM Mon 43 43 W 6 2420 3820 0 Blue 4
8 AM Mon 44 44 W 6 2428 3820 0 Blue 5
9 AM Mon 47 47 W 6 2452 3820 0 Blue 8
10 AM Mon 49 49 W 6 2468 3820 0 Blue 10
11 AM Mon 51 51 W 7 2495 3820 0 Blue 12
12 Noon Mon 53 54 W 7 2566 3820 0 Blue 15
1 PM Mon 55 56 W 7 2710 3820 0 Blue 17
2 PM Mon 56 57 W 7 2769 3820 0 Blue 18
3 PM Mon 56 56 W 7 2710 3820 0 Blue 17
4 PM Mon 56 56 W 7 2710 3820 0 Blue 17
5 PM Mon 55 55 W 9 2612 3820 0 Blue 16
6 PM Mon 53 53 W 9 2528 3820 0 Blue 14
7 PM Mon 51 51 W 9 2495 3820 0 Blue 12
8 PM Mon 49 49 W 9 2468 3820 0 Blue 10
9 PM Mon 47 47 W 9 2452 3820 0 Blue 8
10 PM Mon 45 45 W 9 2436 3820 0 Blue 6
11 PM Mon 43 43 W 6 2420 3820 0 Blue 4
12 Midnight Tue 42 42 W 6 2412 3820 0 Blue 3
1 AM Tue 41 41 W 6 2404 3820 0 Blue 2
2 AM Tue 41 41 W 6 2404 3820 0 Blue 2
3 AM Tue 39 39 W 6 0 3820 0 Blue 0
4 AM Tue 38 38 W 6 0 3820 0 Blue 0
5 AM Tue 38 38 W 7 0 3820 0 Blue 0
6 AM Tue 39 39 W 7 0 3820 0 Blue 0
7 AM Tue 41 41 W 7 2404 3820 0 Blue 2
8 AM Tue 44 44 W 7 2428 3820 0 Blue 5
9 AM Tue 47 48 W 7 2460 3820 0 Blue 9
10 AM Tue 51 53 W 7 2528 3820 0 Blue 14
11 AM Tue 54 57 W 6 2769 3820 0 Blue 18
12 Noon Tue 56 60 W 6 2937 3820 0 Blue 21
1 PM Tue 58 62 W 6 3386 3820 0 Blue 23
2 PM Tue 60 64 W 6 3592 3820 0 Blue 25
3 PM Tue 61 64 W 6 3592 3820 0 Blue 25
4 PM Tue 61 63 W 6 3489 3820 0 Blue 24
5 PM Tue 61 62 W 8 3386 3820 0 Blue 23
6 PM Tue 59 59 W 8 2881 3820 0 Blue 20
7 PM Tue 57 57 W 8 2769 3820 0 Blue 18
8 PM Tue 54 54 W 8 2566 3820 0 Blue 15
9 PM Tue 52 52 W 8 2512 3820 0 Blue 13
10 PM Tue 50 50 W 8 2479 3820 0 Blue 11
11 PM Tue 48 48 W 6 2460 3820 0 Blue 9
12 Midnight Wed 46 46 W 6 2444 3820 0 Blue 7
1 AM Wed 44 44 W 6 2428 3820 0 Blue 5
2 AM Wed 43 43 W 6 2420 3820 0 Blue 4
3 AM Wed 41 41 W 6 2404 3820 0 Blue 2
4 AM Wed 40 40 W 6 2395 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