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

Station:

KOTX

Date/Time:

4 DEC 2020

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)
4 AM Fri 27 27 NE 2 2444 3820 0 Blue 2
5 AM Fri 27 27 NE 2 2444 3820 0 Blue 2
6 AM Fri 26 26 NE 2 2412 3820 0 Blue 1
7 AM Fri 24 24 NE 2 0 3820 0 Blue 0
8 AM Fri 25 25 N 2 0 3820 0 Blue 0
9 AM Fri 27 27 N 2 2444 3820 0 Blue 2
10 AM Fri 28 28 NE 2 2475 3820 0 Blue 3
11 AM Fri 30 31 NE 2 2570 3820 0 Blue 6
12 Noon Fri 30 31 N 2 2570 3820 0 Blue 6
1 PM Fri 33 33 NE 2 2734 3820 0 Blue 8
2 PM Fri 33 33 E 2 2734 3820 0 Blue 8
3 PM Fri 33 33 E 2 2734 3820 0 Blue 8
4 PM Fri 30 30 N 2 2539 3820 0 Blue 5
5 PM Fri 30 30 W 2 2539 3820 0 Blue 5
6 PM Fri 30 30 NW 2 2539 3820 0 Blue 5
7 PM Fri 29 29 NW 2 2507 3820 0 Blue 4
8 PM Fri 29 29 NW 2 2507 3820 0 Blue 4
9 PM Fri 29 29 NW 2 2507 3820 0 Blue 4
10 PM Fri 28 28 NE 2 2475 3820 0 Blue 3
11 PM Fri 28 28 NE 3 2475 3820 0 Blue 3
12 Midnight Sat 27 27 NE 3 2444 3820 0 Blue 2
1 AM Sat 26 26 NE 3 2412 3820 0 Blue 1
2 AM Sat 26 26 NE 2 2412 3820 0 Blue 1
3 AM Sat 26 26 NE 2 2412 3820 0 Blue 1
4 AM Sat 25 25 NE 2 0 3820 0 Blue 0
5 AM Sat 25 25 NE 2 0 3820 0 Blue 0
6 AM Sat 25 25 N 2 0 3820 0 Blue 0
7 AM Sat 24 24 N 2 0 3820 0 Blue 0
8 AM Sat 25 25 N 2 0 3820 0 Blue 0
9 AM Sat 27 27 N 2 2444 3820 0 Blue 2
10 AM Sat 27 27 N 3 2444 3820 0 Blue 2
11 AM Sat 29 29 N 3 2507 3820 0 Blue 4
12 Noon Sat 31 31 N 3 2570 3820 0 Blue 6
1 PM Sat 33 33 N 3 2734 3820 0 Blue 8
2 PM Sat 33 33 N 3 2734 3820 0 Blue 8
3 PM Sat 32 32 N 3 2641 3820 0 Blue 7
4 PM Sat 31 31 NE 3 2570 3820 0 Blue 6
5 PM Sat 31 31 NE 3 2570 3820 0 Blue 6
6 PM Sat 30 30 NE 3 2539 3820 0 Blue 5
7 PM Sat 29 29 N 3 2507 3820 0 Blue 4
8 PM Sat 29 29 N 3 2507 3820 0 Blue 4
9 PM Sat 28 28 N 3 2475 3820 0 Blue 3
10 PM Sat 28 28 NW 5 2475 3820 0 Blue 3
11 PM Sat 27 27 NW 5 2444 3820 0 Blue 2
12 Midnight Sun 27 27 NW 5 2444 3820 0 Blue 2
1 AM Sun 27 27 NW 2 2444 3820 0 Blue 2
2 AM Sun 26 26 NW 2 2412 3820 0 Blue 1
3 AM Sun 26 26 NW 2 2412 3820 0 Blue 1
4 AM Sun 25 25 NW 2 0 3820 0 Blue 0
5 AM Sun 25 25 NW 2 0 3820 0 Blue 0
6 AM Sun 25 25 NW 2 0 3820 0 Blue 0
7 AM Sun 25 25 NE 3 0 3820 0 Blue 0
8 AM Sun 26 26 NE 3 2412 3820 0 Blue 1
9 AM Sun 27 27 NE 3 2444 3820 0 Blue 2
10 AM Sun 29 29 E 3 2507 3820 0 Blue 4
11 AM Sun 31 31 E 3 2570 3820 0 Blue 6
12 Noon Sun 32 32 E 3 2641 3820 0 Blue 7
1 PM Sun 34 34 E 6 2828 3820 0 Blue 9
2 PM Sun 34 34 E 6 2828 3820 0 Blue 9
3 PM Sun 34 34 E 6 2828 3820 0 Blue 9
4 PM Sun 33 33 SE 2 2734 3820 0 Blue 8
5 PM Sun 33 33 SE 2 2734 3820 0 Blue 8
6 PM Sun 32 32 SE 2 2641 3820 0 Blue 7
7 PM Sun 32 32 SE 2 2641 3820 0 Blue 7
8 PM Sun 32 32 SE 2 2641 3820 0 Blue 7
9 PM Sun 31 31 SE 2 2570 3820 0 Blue 6
10 PM Sun 31 31 S 3 2570 3820 0 Blue 6
11 PM Sun 30 30 S 3 2539 3820 0 Blue 5
12 Midnight Mon 30 30 S 3 2539 3820 0 Blue 5
1 AM Mon 29 29 E 2 2507 3820 0 Blue 4
2 AM Mon 29 29 E 2 2507 3820 0 Blue 4
3 AM Mon 29 29 E 2 2507 3820 0 Blue 4
4 AM Mon 28 28 NE 2 2475 3820 0 Blue 3
5 AM Mon 28 28 NE 2 2475 3820 0 Blue 3
6 AM Mon 27 27 NE 2 2444 3820 0 Blue 2
7 AM Mon 27 27 N 5 2444 3820 0 Blue 2
8 AM Mon 27 27 N 5 2444 3820 0 Blue 2
9 AM Mon 28 28 N 5 2475 3820 0 Blue 3
10 AM Mon 29 29 N 6 2507 3820 0 Blue 4
11 AM Mon 30 30 N 6 2539 3820 0 Blue 5
12 Noon Mon 31 31 N 6 2570 3820 0 Blue 6
1 PM Mon 32 32 NE 7 2641 3820 0 Blue 7
2 PM Mon 32 32 NE 7 2641 3820 0 Blue 7
3 PM Mon 32 32 NE 7 2641 3820 0 Blue 7
4 PM Mon 32 32 NE 6 2641 3820 0 Blue 7
5 PM Mon 32 32 NE 6 2641 3820 0 Blue 7
6 PM Mon 31 31 NE 6 2570 3820 0 Blue 6
7 PM Mon 31 31 NW 5 2570 3820 0 Blue 6
8 PM Mon 31 31 NW 5 2570 3820 0 Blue 6
9 PM Mon 31 31 NW 5 2570 3820 0 Blue 6
10 PM Mon 31 31 N 5 2570 3820 0 Blue 6
11 PM Mon 31 31 N 5 2570 3820 0 Blue 6
12 Midnight Tue 30 30 N 5 2539 3820 0 Blue 5
1 AM Tue 30 30 N 5 2539 3820 0 Blue 5
2 AM Tue 30 30 N 5 2539 3820 0 Blue 5
3 AM Tue 30 30 N 5 2539 3820 0 Blue 5
4 AM Tue 30 30 N 5 2539 3820 0 Blue 5
5 AM Tue 30 30 N 5 2539 3820 0 Blue 5
6 AM Tue 29 29 N 5 2507 3820 0 Blue 4
7 AM Tue 29 29 N 5 2507 3820 0 Blue 4
8 AM Tue 29 29 N 5 2507 3820 0 Blue 4
9 AM Tue 30 30 N 5 2539 3820 0 Blue 5
10 AM Tue 31 31 N 5 2570 3820 0 Blue 6
11 AM Tue 32 32 N 5 2641 3820 0 Blue 7
12 Noon Tue 33 33 N 5 2734 3820 0 Blue 8
1 PM Tue 34 34 E 6 2828 3820 0 Blue 9
2 PM Tue 34 34 E 6 2828 3820 0 Blue 9
3 PM Tue 34 34 E 6 2828 3820 0 Blue 9
4 PM Tue 34 34 E 6 2828 3820 0 Blue 9
5 PM Tue 34 34 E 6 2828 3820 0 Blue 9
6 PM Tue 34 34 E 6 2828 3820 0 Blue 9
7 PM Tue 34 34 N 6 2828 3820 0 Blue 9
8 PM Tue 34 34 N 6 2828 3820 0 Blue 9
9 PM Tue 34 34 N 6 2828 3820 0 Blue 9
10 PM Tue 34 34 NW 6 2828 3820 0 Blue 9
11 PM Tue 34 34 NW 6 2828 3820 0 Blue 9
12 Midnight Wed 33 33 NW 6 2734 3820 0 Blue 8
1 AM Wed 33 33 W 6 2734 3820 0 Blue 8
2 AM Wed 32 32 W 6 2641 3820 0 Blue 7
3 AM Wed 32 32 W 6 2641 3820 0 Blue 7
4 AM Wed 31 31 W 6 2570 3820 0 Blue 6
5 AM Wed 31 31 W 6 2570 3820 0 Blue 6
6 AM Wed 31 31 W 6 2570 3820 0 Blue 6
7 AM Wed 31 31 W 6 2570 3820 0 Blue 6
8 AM Wed 32 32 W 6 2641 3820 0 Blue 7
9 AM Wed 33 33 W 6 2734 3820 0 Blue 8
10 AM Wed 34 34 W 6 2828 3820 0 Blue 9
11 AM Wed 35 35 W 6 2921 3820 0 Blue 10
12 Noon Wed 36 36 W 6 3014 3820 0 Blue 11
1 PM Wed 37 37 W 8 3100 3820 0 Blue 12
2 PM Wed 37 37 W 8 3100 3820 0 Blue 12
3 PM Wed 37 37 W 8 3100 3820 0 Blue 12
4 PM Wed 36 36 W 7 3014 3820 0 Blue 11
5 PM Wed 35 35 W 7 2921 3820 0 Blue 10
6 PM Wed 34 34 W 7 2828 3820 0 Blue 9
7 PM Wed 33 33 W 6 2734 3820 0 Blue 8
8 PM Wed 33 33 W 6 2734 3820 0 Blue 8
9 PM Wed 32 32 W 6 2641 3820 0 Blue 7
10 PM Wed 32 32 NW 6 2641 3820 0 Blue 7
11 PM Wed 32 32 NW 6 2641 3820 0 Blue 7
12 Midnight Thu 31 31 NW 6 2570 3820 0 Blue 6
1 AM Thu 31 31 NW 6 2570 3820 0 Blue 6
2 AM Thu 30 30 NW 6 2539 3820 0 Blue 5
3 AM Thu 30 30 NW 6 2539 3820 0 Blue 5

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