Detailed Predictions for: Lake McClure
Launch Altitude (f): 2000
LZ Altitude (f): 500
Sounding

Station:

KOAK

Date/Time:

25 AUG 2019

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 Sun 75 75 N 2 1552 2000 0 Blue 4
6 AM Sun 73 73 NE 3 1452 2000 0 Blue 2
7 AM Sun 74 74 N 3 1502 2000 0 Blue 3
8 AM Sun 80 80 N 2 1801 2000 0 Blue 9
9 AM Sun 85 87 S 2 3165 2229 229 Blue 16
10 AM Sun 88 92 SW 5 5159 3942 1942 Blue 21
11 AM Sun 91 96 W 6 6831 5552 3552 Blue 25
12 Noon Sun 93 100 W 6 7524 7042 5042 Blue 29
1 PM Sun 95 102 W 6 8633 7396 5396 Blue 31
2 PM Sun 97 104 W 7 9046 7670 5670 Blue 33
3 PM Sun 98 104 W 7 9046 7670 5670 Blue 33
4 PM Sun 98 102 W 8 8633 7396 5396 Blue 31
5 PM Sun 98 100 NW 8 7524 7042 5042 Blue 29
6 PM Sun 97 98 NW 8 7310 6424 4424 Blue 27
7 PM Sun 95 95 NW 8 6495 5103 3103 Blue 24
8 PM Sun 89 89 NW 6 3966 2910 910 Blue 18
9 PM Sun 86 86 NW 6 2917 2121 121 Blue 15
10 PM Sun 84 84 NW 5 2232 2000 0 Blue 13
11 PM Sun 82 82 NW 5 2017 2000 0 Blue 11
12 Midnight Mon 81 81 NW 5 1909 2000 0 Blue 10
1 AM Mon 79 79 N 5 1751 2000 0 Blue 8
2 AM Mon 78 78 N 5 1701 2000 0 Blue 7
3 AM Mon 77 77 N 3 1651 2000 0 Blue 6
4 AM Mon 76 76 N 3 1601 2000 0 Blue 5
5 AM Mon 75 75 N 3 1552 2000 0 Blue 4
6 AM Mon 74 74 N 3 1502 2000 0 Blue 3
7 AM Mon 75 75 NE 3 1552 2000 0 Blue 4
8 AM Mon 80 80 NE 2 1801 2000 0 Blue 9
9 AM Mon 86 88 NW 3 3683 2665 665 Blue 17
10 AM Mon 89 92 W 6 5159 3942 1942 Blue 21
11 AM Mon 92 97 W 6 7090 5992 3992 Blue 26
12 Noon Mon 94 101 W 6 8084 7290 5290 Blue 30
1 PM Mon 96 103 W 6 8831 7502 5502 Blue 32
2 PM Mon 97 102 W 7 8633 7396 5396 Blue 31
3 PM Mon 98 102 W 7 8633 7396 5396 Blue 31
4 PM Mon 99 102 W 7 8633 7396 5396 Blue 31
5 PM Mon 98 99 NW 8 7417 6785 4785 Blue 28
6 PM Mon 96 96 NW 8 6831 5552 3552 Blue 25
7 PM Mon 93 93 NW 8 5613 4221 2221 Blue 22
8 PM Mon 90 90 NW 6 4247 3138 1138 Blue 19
9 PM Mon 87 87 NW 6 3165 2229 229 Blue 16
10 PM Mon 84 84 NW 6 2232 2000 0 Blue 13
11 PM Mon 82 82 NW 2 2017 2000 0 Blue 11
12 Midnight Tue 80 80 NW 2 1801 2000 0 Blue 9
1 AM Tue 79 79 NW 2 1751 2000 0 Blue 8
2 AM Tue 78 78 N 3 1701 2000 0 Blue 7
3 AM Tue 77 77 N 3 1651 2000 0 Blue 6
4 AM Tue 76 76 N 3 1601 2000 0 Blue 5
5 AM Tue 76 76 NE 3 1601 2000 0 Blue 5
6 AM Tue 77 77 NE 3 1651 2000 0 Blue 6
7 AM Tue 78 78 NE 3 1701 2000 0 Blue 7
8 AM Tue 81 81 NE 2 1909 2000 0 Blue 10
9 AM Tue 85 87 NE 2 3165 2229 229 Blue 16
10 AM Tue 89 93 NE 2 5613 4221 2221 Blue 22
11 AM Tue 93 98 SW 5 7310 6424 4424 Blue 27
12 Noon Tue 95 102 SW 5 8633 7396 5396 Blue 31
1 PM Tue 97 104 SW 5 9046 7670 5670 Blue 33
2 PM Tue 98 105 W 6 9293 8586 6586 Blue 34
3 PM Tue 100 106 W 6 9540 8782 6782 Blue 35
4 PM Tue 100 104 W 6 9046 7670 5670 Blue 33
5 PM Tue 100 102 W 7 8633 7396 5396 Blue 31
6 PM Tue 98 99 W 7 7417 6785 4785 Blue 28
7 PM Tue 95 95 W 7 6495 5103 3103 Blue 24
8 PM Tue 91 91 NW 6 4437 3661 1661 Blue 20
9 PM Tue 88 88 NW 6 3683 2665 665 Blue 17
10 PM Tue 85 85 NW 6 2719 2014 14 Blue 14
11 PM Tue 83 83 NW 3 2124 2000 0 Blue 12
12 Midnight Wed 81 81 NW 3 1909 2000 0 Blue 10
1 AM Wed 80 80 NW 3 1801 2000 0 Blue 9
2 AM Wed 79 79 N 3 1751 2000 0 Blue 8
3 AM Wed 77 77 N 3 1651 2000 0 Blue 6
4 AM Wed 76 76 N 3 1601 2000 0 Blue 5
5 AM Wed 75 75 NE 3 1552 2000 0 Blue 4
6 AM Wed 76 76 NE 3 1601 2000 0 Blue 5
7 AM Wed 78 78 NE 3 1701 2000 0 Blue 7
8 AM Wed 81 81 S 2 1909 2000 0 Blue 10
9 AM Wed 84 86 S 2 2917 2121 121 Blue 15
10 AM Wed 88 92 S 2 5159 3942 1942 Blue 21
11 AM Wed 91 96 W 6 6831 5552 3552 Blue 25
12 Noon Wed 93 100 W 6 7524 7042 5042 Blue 29
1 PM Wed 95 102 W 6 8633 7396 5396 Blue 31
2 PM Wed 96 103 W 6 8831 7502 5502 Blue 32
3 PM Wed 97 103 W 6 8831 7502 5502 Blue 32
4 PM Wed 98 102 W 6 8633 7396 5396 Blue 31
5 PM Wed 97 99 W 7 7417 6785 4785 Blue 28
6 PM Wed 95 96 W 7 6831 5552 3552 Blue 25
7 PM Wed 91 91 W 7 4437 3661 1661 Blue 20
8 PM Wed 88 88 NW 6 3683 2665 665 Blue 17
9 PM Wed 85 85 NW 6 2719 2014 14 Blue 14
10 PM Wed 82 82 NW 6 2017 2000 0 Blue 11
11 PM Wed 80 80 NW 3 1801 2000 0 Blue 9
12 Midnight Thu 78 78 NW 3 1701 2000 0 Blue 7
1 AM Thu 77 77 NW 3 1651 2000 0 Blue 6
2 AM Thu 76 76 NW 3 1601 2000 0 Blue 5
3 AM Thu 75 75 NW 3 1552 2000 0 Blue 4
4 AM Thu 74 74 NW 3 1502 2000 0 Blue 3
5 AM Thu 74 74 NW 3 1502 2000 0 Blue 3
6 AM Thu 75 75 NW 3 1552 2000 0 Blue 4
7 AM Thu 76 76 NW 3 1601 2000 0 Blue 5
8 AM Thu 78 78 W 2 1701 2000 0 Blue 7
9 AM Thu 81 83 W 2 2124 2000 0 Blue 12
10 AM Thu 85 89 W 2 3966 2910 910 Blue 18
11 AM Thu 88 93 W 6 5613 4221 2221 Blue 22
12 Noon Thu 90 97 W 6 7090 5992 3992 Blue 26
1 PM Thu 92 99 W 6 7417 6785 4785 Blue 28
2 PM Thu 93 100 W 7 7524 7042 5042 Blue 29
3 PM Thu 94 100 W 7 7524 7042 5042 Blue 29
4 PM Thu 95 99 W 7 7417 6785 4785 Blue 28
5 PM Thu 94 96 W 8 6831 5552 3552 Blue 25
6 PM Thu 92 93 W 8 5613 4221 2221 Blue 22
7 PM Thu 89 89 W 8 3966 2910 910 Blue 18
8 PM Thu 86 86 NW 6 2917 2121 121 Blue 15
9 PM Thu 83 83 NW 6 2124 2000 0 Blue 12
10 PM Thu 80 80 NW 6 1801 2000 0 Blue 9
11 PM Thu 78 78 N 3 1701 2000 0 Blue 7
12 Midnight Fri 76 76 N 3 1601 2000 0 Blue 5
1 AM Fri 75 75 N 3 1552 2000 0 Blue 4
2 AM Fri 74 74 N 5 1502 2000 0 Blue 3
3 AM Fri 73 73 N 5 1452 2000 0 Blue 2
4 AM Fri 72 72 N 5 1402 2000 0 Blue 1
5 AM Fri 72 72 N 3 1402 2000 0 Blue 1
6 AM Fri 73 73 N 3 1452 2000 0 Blue 2
7 AM Fri 75 75 N 3 1552 2000 0 Blue 4
8 AM Fri 77 77 W 2 1651 2000 0 Blue 6
9 AM Fri 80 82 W 2 2017 2000 0 Blue 11
10 AM Fri 84 88 W 2 3683 2665 665 Blue 17
11 AM Fri 87 92 W 6 5159 3942 1942 Blue 21
12 Noon Fri 89 96 W 6 6831 5552 3552 Blue 25
1 PM Fri 91 98 W 6 7310 6424 4424 Blue 27
2 PM Fri 92 99 W 8 7417 6785 4785 Blue 28
3 PM Fri 93 99 W 8 7417 6785 4785 Blue 28
4 PM Fri 94 98 W 8 7310 6424 4424 Blue 27
5 PM Fri 93 95 W 9 6495 5103 3103 Blue 24
6 PM Fri 91 92 W 9 5159 3942 1942 Blue 21
7 PM Fri 88 88 W 9 3683 2665 665 Blue 17
8 PM Fri 85 85 NW 6 2719 2014 14 Blue 14
9 PM Fri 82 82 NW 6 2017 2000 0 Blue 11
10 PM Fri 80 80 NW 6 1801 2000 0 Blue 9
11 PM Fri 78 78 NW 3 1701 2000 0 Blue 7
12 Midnight Sat 76 76 NW 3 1601 2000 0 Blue 5
1 AM Sat 74 74 NW 3 1502 2000 0 Blue 3
2 AM Sat 73 73 N 3 1452 2000 0 Blue 2
3 AM Sat 71 71 N 3 1352 2000 0 Blue 0
4 AM Sat 70 70 N 3 1304 2000 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