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

Station:

KOTX

Date/Time:

18 JAN 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)
4 AM Thu 33 33 SW 6 0 3820 0 Blue 0
5 AM Thu 33 33 SW 7 0 3820 0 Blue 0
6 AM Thu 34 34 W 8 0 3820 0 Blue 0
7 AM Thu 34 34 SW 3 0 3820 0 Blue 0
8 AM Thu 34 34 SW 6 0 3820 0 Blue 0
9 AM Thu 35 35 W 6 0 3820 0 Blue 0
10 AM Thu 36 36 SW 3 2415 3820 0 Blue 1
11 AM Thu 37 37 SW 7 2456 3820 0 Blue 2
12 Noon Thu 38 38 SW 7 2498 3820 0 Blue 3
1 PM Thu 39 39 SW 7 2539 3820 0 Blue 4
2 PM Thu 39 39 S 7 2539 3820 0 Blue 4
3 PM Thu 38 38 S 7 2498 3820 0 Blue 3
4 PM Thu 36 36 S 7 2415 3820 0 Blue 1
5 PM Thu 35 35 S 7 0 3820 0 Blue 0
6 PM Thu 33 33 SW 6 0 3820 0 Blue 0
7 PM Thu 32 32 SW 6 0 3820 0 Blue 0
8 PM Thu 32 32 SW 6 0 3820 0 Blue 0
9 PM Thu 32 32 SW 5 0 3820 0 Blue 0
10 PM Thu 31 31 SW 5 0 3820 0 Blue 0
11 PM Thu 31 31 SW 6 0 3820 0 Blue 0
12 Midnight Fri 30 30 SW 6 0 3820 0 Blue 0
1 AM Fri 30 30 SW 6 0 3820 0 Blue 0
2 AM Fri 29 29 SW 5 0 3820 0 Blue 0
3 AM Fri 29 29 SW 5 0 3820 0 Blue 0
4 AM Fri 29 29 SW 5 0 3820 0 Blue 0
5 AM Fri 28 28 SW 5 0 3820 0 Blue 0
6 AM Fri 28 28 SW 5 0 3820 0 Blue 0
7 AM Fri 28 28 SW 5 0 3820 0 Blue 0
8 AM Fri 28 28 SW 5 0 3820 0 Blue 0
9 AM Fri 29 29 SW 5 0 3820 0 Blue 0
10 AM Fri 30 30 SW 5 0 3820 0 Blue 0
11 AM Fri 32 32 SW 5 0 3820 0 Blue 0
12 Noon Fri 33 33 S 5 0 3820 0 Blue 0
1 PM Fri 34 34 S 5 0 3820 0 Blue 0
2 PM Fri 34 34 S 5 0 3820 0 Blue 0
3 PM Fri 34 34 S 3 0 3820 0 Blue 0
4 PM Fri 33 33 S 3 0 3820 0 Blue 0
5 PM Fri 31 31 S 3 0 3820 0 Blue 0
6 PM Fri 30 30 S 3 0 3820 0 Blue 0
7 PM Fri 28 28 SW 3 0 3820 0 Blue 0
8 PM Fri 28 28 SW 3 0 3820 0 Blue 0
9 PM Fri 27 27 W 2 0 3820 0 Blue 0
10 PM Fri 27 27 W 2 0 3820 0 Blue 0
11 PM Fri 27 27 W 2 0 3820 0 Blue 0
12 Midnight Sat 27 27 SW 2 0 3820 0 Blue 0
1 AM Sat 27 27 SW 2 0 3820 0 Blue 0
2 AM Sat 27 27 SW 2 0 3820 0 Blue 0
3 AM Sat 27 27 NW 2 0 3820 0 Blue 0
4 AM Sat 26 26 N 2 0 3820 0 Blue 0
5 AM Sat 26 26 NW 2 0 3820 0 Blue 0
6 AM Sat 26 26 W 3 0 3820 0 Blue 0
7 AM Sat 26 26 SW 3 0 3820 0 Blue 0
8 AM Sat 27 27 SW 3 0 3820 0 Blue 0
9 AM Sat 29 29 SW 2 0 3820 0 Blue 0
10 AM Sat 30 30 SW 2 0 3820 0 Blue 0
11 AM Sat 32 32 SW 3 0 3820 0 Blue 0
12 Noon Sat 34 34 SW 3 0 3820 0 Blue 0
1 PM Sat 35 35 SW 5 0 3820 0 Blue 0
2 PM Sat 36 36 SW 3 2415 3820 0 Blue 1
3 PM Sat 36 36 SW 3 2415 3820 0 Blue 1
4 PM Sat 34 34 SW 2 0 3820 0 Blue 0
5 PM Sat 32 32 SW 2 0 3820 0 Blue 0
6 PM Sat 30 30 SW 3 0 3820 0 Blue 0
7 PM Sat 28 28 SW 3 0 3820 0 Blue 0
8 PM Sat 27 27 SW 3 0 3820 0 Blue 0
9 PM Sat 27 27 SW 2 0 3820 0 Blue 0
10 PM Sat 28 28 SW 2 0 3820 0 Blue 0
11 PM Sat 28 28 SW 2 0 3820 0 Blue 0
12 Midnight Sun 27 27 SW 3 0 3820 0 Blue 0
1 AM Sun 26 26 S 3 0 3820 0 Blue 0
2 AM Sun 26 26 S 3 0 3820 0 Blue 0
3 AM Sun 25 25 SE 2 0 3820 0 Blue 0
4 AM Sun 25 25 SE 2 0 3820 0 Blue 0
5 AM Sun 25 25 SE 2 0 3820 0 Blue 0
6 AM Sun 25 25 SE 2 0 3820 0 Blue 0
7 AM Sun 25 25 SE 2 0 3820 0 Blue 0
8 AM Sun 25 25 SE 3 0 3820 0 Blue 0
9 AM Sun 25 25 E 3 0 3820 0 Blue 0
10 AM Sun 25 25 E 3 0 3820 0 Blue 0
11 AM Sun 27 27 E 3 0 3820 0 Blue 0
12 Noon Sun 29 29 SE 3 0 3820 0 Blue 0
1 PM Sun 30 30 SE 2 0 3820 0 Blue 0
2 PM Sun 31 31 SE 2 0 3820 0 Blue 0
3 PM Sun 31 31 SE 2 0 3820 0 Blue 0
4 PM Sun 31 31 SE 2 0 3820 0 Blue 0
5 PM Sun 31 31 SE 2 0 3820 0 Blue 0
6 PM Sun 31 31 SE 2 0 3820 0 Blue 0
7 PM Sun 31 31 SE 2 0 3820 0 Blue 0
8 PM Sun 30 30 SE 2 0 3820 0 Blue 0
9 PM Sun 29 29 SE 2 0 3820 0 Blue 0
10 PM Sun 28 28 W 5 0 3820 0 Blue 0
11 PM Sun 27 27 W 5 0 3820 0 Blue 0
12 Midnight Mon 27 27 W 5 0 3820 0 Blue 0
1 AM Mon 26 26 W 5 0 3820 0 Blue 0
2 AM Mon 26 26 W 5 0 3820 0 Blue 0
3 AM Mon 26 26 W 5 0 3820 0 Blue 0
4 AM Mon 26 26 W 6 0 3820 0 Blue 0
5 AM Mon 25 25 W 6 0 3820 0 Blue 0
6 AM Mon 25 25 W 6 0 3820 0 Blue 0
7 AM Mon 25 25 W 6 0 3820 0 Blue 0
8 AM Mon 27 27 W 6 0 3820 0 Blue 0
9 AM Mon 29 29 W 6 0 3820 0 Blue 0
10 AM Mon 31 31 W 5 0 3820 0 Blue 0
11 AM Mon 33 33 W 5 0 3820 0 Blue 0
12 Noon Mon 34 34 W 5 0 3820 0 Blue 0
1 PM Mon 35 35 W 5 0 3820 0 Blue 0
2 PM Mon 35 35 W 5 0 3820 0 Blue 0
3 PM Mon 34 34 W 5 0 3820 0 Blue 0
4 PM Mon 33 33 SW 5 0 3820 0 Blue 0
5 PM Mon 32 32 SW 5 0 3820 0 Blue 0
6 PM Mon 30 30 SW 5 0 3820 0 Blue 0
7 PM Mon 28 28 SW 5 0 3820 0 Blue 0
8 PM Mon 27 27 SW 5 0 3820 0 Blue 0
9 PM Mon 27 27 SW 5 0 3820 0 Blue 0
10 PM Mon 27 27 W 5 0 3820 0 Blue 0
11 PM Mon 27 27 W 5 0 3820 0 Blue 0
12 Midnight Tue 27 27 W 5 0 3820 0 Blue 0
1 AM Tue 27 27 W 5 0 3820 0 Blue 0
2 AM Tue 26 26 W 5 0 3820 0 Blue 0
3 AM Tue 26 26 W 5 0 3820 0 Blue 0
4 AM Tue 26 26 NW 5 0 3820 0 Blue 0
5 AM Tue 25 25 NW 5 0 3820 0 Blue 0
6 AM Tue 24 24 NW 5 0 3820 0 Blue 0
7 AM Tue 24 24 NW 5 0 3820 0 Blue 0
8 AM Tue 24 24 NW 5 0 3820 0 Blue 0
9 AM Tue 25 25 NW 5 0 3820 0 Blue 0
10 AM Tue 27 27 N 3 0 3820 0 Blue 0
11 AM Tue 29 29 N 3 0 3820 0 Blue 0
12 Noon Tue 30 30 N 3 0 3820 0 Blue 0
1 PM Tue 31 31 N 3 0 3820 0 Blue 0
2 PM Tue 31 31 N 3 0 3820 0 Blue 0
3 PM Tue 30 30 N 3 0 3820 0 Blue 0
4 PM Tue 28 28 NE 2 0 3820 0 Blue 0
5 PM Tue 27 27 NE 2 0 3820 0 Blue 0
6 PM Tue 26 26 NE 2 0 3820 0 Blue 0
7 PM Tue 25 25 NE 2 0 3820 0 Blue 0
8 PM Tue 25 25 NE 2 0 3820 0 Blue 0
9 PM Tue 25 25 NE 2 0 3820 0 Blue 0
10 PM Tue 25 25 N 2 0 3820 0 Blue 0
11 PM Tue 25 25 N 2 0 3820 0 Blue 0
12 Midnight Wed 25 25 N 2 0 3820 0 Blue 0
1 AM Wed 25 25 N 2 0 3820 0 Blue 0
2 AM Wed 26 26 N 2 0 3820 0 Blue 0
3 AM Wed 26 26 N 2 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