Detailed Predictions for: Potato Hill
Launch Lat, Long, Altitude (f): 39.34098, -122.69, 3400
LZ Altitude (f): 1700
Sounding

Station:

KOAK

Date/Time:

21 SEP 2021

Temp/Wind data from:

NOAA Digital Forecast

Site Forecasts
Time
(Local)
High
Temp

Puddle
Temp

Wind
(mph)
Wind
Gust
Thermal
Ceiling

(ft)
Soaring
Ceiling

(ft)
Above
Launch

(ft)
Thermal
Type
Thermal
Index

(F)
12 Midnight Mon 59 57 N 10 16 2621 3400 0 Blue 0
1 AM Mon 59 57 N 10 16 2621 3400 0 Blue 0
2 AM Mon 59 57 N 11 17 2621 3400 0 Blue 0
3 AM Mon 58 56 N 11 17 2621 3400 0 Blue 0
4 AM Mon 59 57 N 11 17 2621 3400 0 Blue 0
5 AM Mon 58 56 NNW 12 19 2621 3400 0 Blue 0
6 AM Mon 58 56 NNW 12 19 2621 3400 0 Blue 0
7 AM Mon 58 56 NNW 12 19 2621 3400 0 Blue 0
8 AM Mon 64 62 N 13 20 2621 3400 0 Blue 0
9 AM Mon 69 68 N 13 20 2621 3400 0 Blue 0
10 AM Mon 72 72 N 13 20 2621 3400 0 Blue 0
11 AM Mon 74 76 N 12 20 4050 3445 45 Blue 3
12 Noon Mon 79 82 N 12 20 5023 4692 1292 Blue 9
1 PM Mon 82 86 N 12 20 6199 5079 1679 Blue 13
2 PM Mon 84 87 N 11 17 6729 5140 1740 Blue 14
3 PM Mon 86 88 N 11 17 7056 5605 2205 Blue 15
4 PM Mon 87 88 N 11 17 7056 5605 2205 Blue 15
5 PM Mon 87 86 N 10 16 6199 5079 1679 Blue 13
6 PM Mon 81 79 N 10 16 4699 4036 636 Blue 6
7 PM Mon 74 72 N 10 16 2621 3400 0 Blue 0
8 PM Mon 73 71 N 9 14 2621 3400 0 Blue 0
9 PM Mon 72 70 N 9 14 2621 3400 0 Blue 0
10 PM Mon 71 69 N 9 14 2621 3400 0 Blue 0
11 PM Mon 68 66 N 8 12 2621 3400 0 Blue 0
12 Midnight Tue 67 65 N 8 12 2621 3400 0 Blue 0
1 AM Tue 68 66 N 8 12 2621 3400 0 Blue 0
2 AM Tue 67 65 NNW 5 9 2621 3400 0 Blue 0
3 AM Tue 66 64 NNW 5 9 2621 3400 0 Blue 0
4 AM Tue 65 63 NNW 5 9 2621 3400 0 Blue 0
5 AM Tue 64 62 NW 5 9 2621 3400 0 Blue 0
6 AM Tue 64 62 NW 5 9 2621 3400 0 Blue 0
7 AM Tue 66 64 NW 5 9 2621 3400 0 Blue 0
8 AM Tue 69 65 NW 6 10 2621 3400 0 Blue 0
9 AM Tue 74 60 NW 6 10 2621 3400 0 Blue 0
10 AM Tue 75 46 NW 6 10 2621 3400 0 Blue 0
11 AM Tue 77 33 N 5 9 2621 3400 0 Blue 0
12 Noon Tue 80 24 N 5 9 2621 3400 0 Blue 0
1 PM Tue 82 20 N 5 9 2621 3400 0 Blue 0
2 PM Tue 84 87 SE 6 10 6729 5140 1740 Blue 14
3 PM Tue 86 88 SE 6 10 7056 5605 2205 Blue 15
4 PM Tue 86 87 SE 6 10 6729 5140 1740 Blue 14
5 PM Tue 84 83 S 10 16 5084 4802 1402 Blue 10
6 PM Tue 81 79 S 10 16 4699 4036 636 Blue 6
7 PM Tue 77 75 S 10 16 3906 3400 0 Blue 2
8 PM Tue 73 71 S 6 10 2621 3400 0 Blue 0
9 PM Tue 71 69 S 6 10 2621 3400 0 Blue 0
10 PM Tue 70 68 S 6 10 2621 3400 0 Blue 0
11 PM Tue 69 67 WSW 6 10 2621 3400 0 Blue 0
12 Midnight Wed 69 67 WSW 6 10 2621 3400 0 Blue 0
1 AM Wed 69 67 WSW 6 10 2621 3400 0 Blue 0
2 AM Wed 69 67 WSW 9 13 2621 3400 0 Blue 0
3 AM Wed 68 66 WSW 9 13 2621 3400 0 Blue 0
4 AM Wed 67 65 WSW 9 13 2621 3400 0 Blue 0
5 AM Wed 67 65 SW 8 12 2621 3400 0 Blue 0
6 AM Wed 68 66 SW 8 12 2621 3400 0 Blue 0
7 AM Wed 70 68 SW 8 12 2621 3400 0 Blue 0
8 AM Wed 72 70 W 3 3 2621 3400 0 Blue 0
9 AM Wed 75 74 W 3 3 3830 3400 0 Blue 1
10 AM Wed 78 78 W 3 3 4589 3903 503 Blue 5
11 AM Wed 81 83 SSE 5 9 5084 4802 1402 Blue 10
12 Noon Wed 84 87 SSE 5 9 6729 5140 1740 Blue 14
1 PM Wed 86 89 SSE 5 9 7260 6142 2742 Blue 16
2 PM Wed 88 91 SW 10 16 7717 7029 3629 Blue 18
3 PM Wed 89 91 SW 10 16 7717 7029 3629 Blue 18
4 PM Wed 89 90 SW 10 16 7471 6664 3264 Blue 17
5 PM Wed 87 86 S 8 12 6199 5079 1679 Blue 13
6 PM Wed 82 80 S 8 12 4809 4385 985 Blue 7
7 PM Wed 76 74 S 8 12 3830 3400 0 Blue 1
8 PM Wed 71 69 W 8 12 2621 3400 0 Blue 0
9 PM Wed 68 66 W 8 12 2621 3400 0 Blue 0
10 PM Wed 68 66 W 8 12 2621 3400 0 Blue 0
11 PM Wed 68 66 N 6 10 2621 3400 0 Blue 0
12 Midnight Thu 67 65 N 6 10 2621 3400 0 Blue 0
1 AM Thu 66 64 N 6 10 2621 3400 0 Blue 0
2 AM Thu 65 63 N 6 10 2621 3400 0 Blue 0
3 AM Thu 64 62 N 6 10 2621 3400 0 Blue 0
4 AM Thu 64 62 N 6 10 2621 3400 0 Blue 0
5 AM Thu 64 62 NNE 8 12 2621 3400 0 Blue 0
6 AM Thu 66 64 NNE 8 12 2621 3400 0 Blue 0
7 AM Thu 68 66 NNE 8 12 2621 3400 0 Blue 0
8 AM Thu 71 69 N 8 12 2621 3400 0 Blue 0
9 AM Thu 74 73 N 8 12 3472 3400 0 Blue 0
10 AM Thu 78 78 N 8 12 4589 3903 503 Blue 5
11 AM Thu 82 83 NNE 9 13 5084 4802 1402 Blue 10
12 Noon Thu 85 88 NNE 9 13 7056 5605 2205 Blue 15
1 PM Thu 88 91 NNE 9 13 7717 7029 3629 Blue 18
2 PM Thu 90 93 NE 10 16 8026 7434 4034 Blue 20
3 PM Thu 92 94 NE 10 16 8337 7679 4279 Blue 21
4 PM Thu 93 94 NE 10 16 8337 7679 4279 Blue 21
5 PM Thu 91 90 N 8 12 7471 6664 3264 Blue 17
6 PM Thu 87 85 N 8 12 5654 5019 1619 Blue 12
7 PM Thu 82 80 N 8 12 4809 4385 985 Blue 7
8 PM Thu 78 76 NW 8 12 4050 3445 45 Blue 3
9 PM Thu 75 73 NW 8 12 3472 3400 0 Blue 0
10 PM Thu 74 72 NW 8 12 2621 3400 0 Blue 0
11 PM Thu 74 72 NE 6 10 2621 3400 0 Blue 0
12 Midnight Fri 74 72 NE 6 10 2621 3400 0 Blue 0
1 AM Fri 73 71 NE 6 10 2621 3400 0 Blue 0
2 AM Fri 72 70 NNW 8 12 2621 3400 0 Blue 0
3 AM Fri 71 69 NNW 8 12 2621 3400 0 Blue 0
4 AM Fri 69 67 NNW 8 12 2621 3400 0 Blue 0
5 AM Fri 69 67 NE 6 10 2621 3400 0 Blue 0
6 AM Fri 70 68 NE 6 10 2621 3400 0 Blue 0
7 AM Fri 72 70 NE 6 10 2621 3400 0 Blue 0
8 AM Fri 74 72 NNW 4 6 2621 3400 0 Blue 0
9 AM Fri 78 77 NNW 4 6 4403 3827 427 Blue 4
10 AM Fri 81 81 NNW 4 6 4919 4583 1183 Blue 8
11 AM Fri 85 87 E 5 9 6729 5140 1740 Blue 14
12 Noon Fri 88 91 E 5 9 7717 7029 3629 Blue 18
1 PM Fri 91 94 E 5 9 8337 7679 4279 Blue 21
2 PM Fri 93 96 SE 5 9 9236 8009 4609 Blue 23
3 PM Fri 95 97 SE 5 9 9562 8242 4842 Blue 24
4 PM Fri 95 96 SE 5 9 9236 8009 4609 Blue 23
5 PM Fri 93 92 SSW 6 10 7924 7231 3831 Blue 19
6 PM Fri 88 86 SSW 6 10 6199 5079 1679 Blue 13
7 PM Fri 82 80 SSW 6 10 4809 4385 985 Blue 7
8 PM Fri 77 75 W 5 9 3906 3400 0 Blue 2
9 PM Fri 75 73 W 5 9 3472 3400 0 Blue 0
10 PM Fri 74 72 W 5 9 2621 3400 0 Blue 0
11 PM Fri 73 71 W 5 9 2621 3400 0 Blue 0
12 Midnight Sat 73 71 W 5 9 2621 3400 0 Blue 0
1 AM Sat 72 70 W 5 9 2621 3400 0 Blue 0
2 AM Sat 71 69 WNW 5 9 2621 3400 0 Blue 0
3 AM Sat 70 68 WNW 5 9 2621 3400 0 Blue 0
4 AM Sat 68 66 WNW 5 9 2621 3400 0 Blue 0
5 AM Sat 68 66 NNW 4 6 2621 3400 0 Blue 0
6 AM Sat 69 67 NNW 4 6 2621 3400 0 Blue 0
7 AM Sat 71 69 NNW 4 6 2621 3400 0 Blue 0
8 AM Sat 73 71 NNW 3 5 2621 3400 0 Blue 0
9 AM Sat 76 75 NNW 3 5 3906 3400 0 Blue 2
10 AM Sat 80 80 NNW 3 5 4809 4385 985 Blue 7
11 AM Sat 83 84 SW 5 9 5145 4911 1511 Blue 11
12 Noon Sat 85 87 SW 5 9 6729 5140 1740 Blue 14
1 PM Sat 87 90 SW 5 9 7471 6664 3264 Blue 17
2 PM Sat 89 91 SSW 6 10 7717 7029 3629 Blue 18
3 PM Sat 91 93 SSW 6 10 8026 7434 4034 Blue 20
4 PM Sat 91 91 SSW 6 10 7717 7029 3629 Blue 18
5 PM Sat 89 88 SW 6 10 7056 5605 2205 Blue 15
6 PM Sat 85 83 SW 6 10 5084 4802 1402 Blue 10
7 PM Sat 79 77 SW 6 10 4403 3827 427 Blue 4
8 PM Sat 74 72 W 5 9 2621 3400 0 Blue 0
9 PM Sat 72 70 W 5 9 2621 3400 0 Blue 0
10 PM Sat 71 69 W 5 9 2621 3400 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 or WeatherAPI.com website.  Puddle temperatures can exceed this temperature. 

Puddle Temp: This estimate is based on the High Temp and the National Weather Service or WeatherAPI.com 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 or WeatherAPI.com website.

Wind Gust: This estimate is taken from the National Weather Service or WeatherAPI.com 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 [email protected]