Detailed Predictions for: Potato Hill
Launch Altitude (f): 3400
LZ Altitude (f): 1700
Sounding

Station:

KOAK

Date/Time:

17 FEB 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)
4 AM Sun 31 29 SW 6 2579 3400 0 Blue 0
5 AM Sun 30 28 SW 6 2579 3400 0 Blue 0
6 AM Sun 30 28 SW 6 2579 3400 0 Blue 0
7 AM Sun 30 28 NW 6 2579 3400 0 Blue 0
8 AM Sun 32 30 NW 6 2579 3400 0 Blue 0
9 AM Sun 34 32 NW 6 2579 3400 0 Blue 0
10 AM Sun 36 34 N 5 2579 3400 0 Blue 0
11 AM Sun 38 36 N 5 2827 3400 0 Blue 0
12 Noon Sun 40 39 N 5 4518 3400 0 Blue 2
1 PM Sun 41 40 N 7 4801 3712 312 White 3
2 PM Sun 42 40 N 7 4801 3712 312 White 3
3 PM Sun 42 40 N 7 4801 3712 312 White 3
4 PM Sun 41 39 N 8 4518 3400 0 Blue 2
5 PM Sun 39 37 N 8 3740 3400 0 Blue 0
6 PM Sun 37 35 N 8 2579 3400 0 Blue 0
7 PM Sun 35 33 N 9 2579 3400 0 Blue 0
8 PM Sun 34 32 N 9 2579 3400 0 Blue 0
9 PM Sun 34 32 N 9 2579 3400 0 Blue 0
10 PM Sun 33 31 N 10 2579 3400 0 Blue 0
11 PM Sun 32 30 N 10 2579 3400 0 Blue 0
12 Midnight Mon 31 29 N 10 2579 3400 0 Blue 0
1 AM Mon 30 28 N 10 2579 3400 0 Blue 0
2 AM Mon 30 28 N 10 2579 3400 0 Blue 0
3 AM Mon 29 27 N 10 2579 3400 0 Blue 0
4 AM Mon 29 27 N 9 2579 3400 0 Blue 0
5 AM Mon 28 26 N 9 2579 3400 0 Blue 0
6 AM Mon 28 26 N 9 2579 3400 0 Blue 0
7 AM Mon 29 27 N 9 2579 3400 0 Blue 0
8 AM Mon 32 30 N 9 2579 3400 0 Blue 0
9 AM Mon 37 36 N 9 2827 3400 0 Blue 0
10 AM Mon 41 41 N 13 5017 4122 722 White 4
11 AM Mon 44 45 N 13 5876 5876 2476 White 8
12 Noon Mon 47 48 N 13 6513 6513 3113 White 11
1 PM Mon 49 50 N 13 6935 6935 3535 White 13
2 PM Mon 50 50 N 13 6935 6935 3535 White 13
3 PM Mon 50 49 N 13 6724 6724 3324 White 12
4 PM Mon 49 47 N 9 6301 6301 2901 White 10
5 PM Mon 45 43 N 9 5446 5446 2046 White 6
6 PM Mon 41 39 N 9 4518 3400 0 Blue 2
7 PM Mon 38 36 N 9 2827 3400 0 Blue 0
8 PM Mon 36 34 N 9 2579 3400 0 Blue 0
9 PM Mon 35 33 N 9 2579 3400 0 Blue 0
10 PM Mon 35 33 N 10 2579 3400 0 Blue 0
11 PM Mon 34 32 N 10 2579 3400 0 Blue 0
12 Midnight Tue 33 31 N 10 2579 3400 0 Blue 0
1 AM Tue 31 29 N 10 2579 3400 0 Blue 0
2 AM Tue 30 28 N 10 2579 3400 0 Blue 0
3 AM Tue 30 28 N 10 2579 3400 0 Blue 0
4 AM Tue 29 27 N 8 2579 3400 0 Blue 0
5 AM Tue 28 26 N 8 2579 3400 0 Blue 0
6 AM Tue 28 26 N 8 2579 3400 0 Blue 0
7 AM Tue 29 27 N 8 2579 3400 0 Blue 0
8 AM Tue 32 30 N 8 2579 3400 0 Blue 0
9 AM Tue 36 35 N 8 2579 3400 0 Blue 0
10 AM Tue 41 41 N 9 5017 4122 722 White 4
11 AM Tue 45 46 N 9 6089 6089 2689 White 9
12 Noon Tue 48 49 N 9 6724 6724 3324 White 12
1 PM Tue 50 51 N 9 7145 7145 3745 White 14
2 PM Tue 51 51 N 9 7145 7145 3745 White 14
3 PM Tue 51 50 N 9 6935 6935 3535 White 13
4 PM Tue 49 47 SE 5 6301 6301 2901 White 10
5 PM Tue 46 44 SE 5 5661 5661 2261 White 7
6 PM Tue 43 41 SE 5 5017 4122 722 White 4
7 PM Tue 41 39 SE 5 4518 3400 0 Blue 2
8 PM Tue 39 37 SE 5 3740 3400 0 Blue 0
9 PM Tue 39 37 SE 5 3740 3400 0 Blue 0
10 PM Tue 38 36 N 5 2827 3400 0 Blue 0
11 PM Tue 37 35 N 5 2579 3400 0 Blue 0
12 Midnight Wed 36 34 N 5 2579 3400 0 Blue 0
1 AM Wed 35 33 N 5 2579 3400 0 Blue 0
2 AM Wed 35 33 N 5 2579 3400 0 Blue 0
3 AM Wed 34 32 N 5 2579 3400 0 Blue 0
4 AM Wed 33 31 NW 6 2579 3400 0 Blue 0
5 AM Wed 32 30 NW 6 2579 3400 0 Blue 0
6 AM Wed 31 29 NW 6 2579 3400 0 Blue 0
7 AM Wed 31 29 NW 6 2579 3400 0 Blue 0
8 AM Wed 33 31 NW 6 2579 3400 0 Blue 0
9 AM Wed 36 34 NW 6 2579 3400 0 Blue 0
10 AM Wed 40 39 W 7 4518 3400 0 Blue 2
11 AM Wed 43 42 W 7 5232 4495 1095 White 5
12 Noon Wed 45 44 W 7 5661 5661 2261 White 7
1 PM Wed 47 46 W 7 6089 6089 2689 White 9
2 PM Wed 47 46 W 7 6089 6089 2689 White 9
3 PM Wed 46 44 W 7 5661 5661 2261 White 7
4 PM Wed 45 43 NW 9 5446 5446 2046 White 6
5 PM Wed 43 41 NW 9 5017 4122 722 White 4
6 PM Wed 41 39 NW 9 4518 3400 0 Blue 2
7 PM Wed 39 37 NW 9 3740 3400 0 Blue 0
8 PM Wed 38 36 NW 9 2827 3400 0 Blue 0
9 PM Wed 37 35 NW 9 2579 3400 0 Blue 0
10 PM Wed 37 35 NW 10 2579 3400 0 Blue 0
11 PM Wed 36 34 NW 10 2579 3400 0 Blue 0
12 Midnight Thu 36 34 NW 10 2579 3400 0 Blue 0
1 AM Thu 35 33 NW 10 2579 3400 0 Blue 0
2 AM Thu 35 33 NW 10 2579 3400 0 Blue 0
3 AM Thu 34 32 NW 10 2579 3400 0 Blue 0
4 AM Thu 33 31 NW 10 2579 3400 0 Blue 0
5 AM Thu 32 30 NW 10 2579 3400 0 Blue 0
6 AM Thu 31 29 NW 10 2579 3400 0 Blue 0
7 AM Thu 31 29 NW 10 2579 3400 0 Blue 0
8 AM Thu 33 31 NW 10 2579 3400 0 Blue 0
9 AM Thu 35 33 NW 10 2579 3400 0 Blue 0
10 AM Thu 37 36 N 12 2827 3400 0 Blue 0
11 AM Thu 39 39 N 12 4518 3400 0 Blue 2
12 Noon Thu 40 40 N 12 4801 3712 312 White 3
1 PM Thu 40 40 N 12 4801 3712 312 White 3
2 PM Thu 40 39 N 12 4518 3400 0 Blue 2
3 PM Thu 40 39 N 12 4518 3400 0 Blue 2
4 PM Thu 39 37 N 14 3740 3400 0 Blue 0
5 PM Thu 38 36 N 14 2827 3400 0 Blue 0
6 PM Thu 36 34 N 14 2579 3400 0 Blue 0
7 PM Thu 35 33 N 14 2579 3400 0 Blue 0
8 PM Thu 34 32 N 14 2579 3400 0 Blue 0
9 PM Thu 34 32 N 14 2579 3400 0 Blue 0
10 PM Thu 34 32 N 10 2579 3400 0 Blue 0
11 PM Thu 33 31 N 10 2579 3400 0 Blue 0
12 Midnight Fri 33 31 N 10 2579 3400 0 Blue 0
1 AM Fri 32 30 N 10 2579 3400 0 Blue 0
2 AM Fri 31 29 N 10 2579 3400 0 Blue 0
3 AM Fri 31 29 N 10 2579 3400 0 Blue 0
4 AM Fri 30 28 N 10 2579 3400 0 Blue 0
5 AM Fri 30 28 N 10 2579 3400 0 Blue 0
6 AM Fri 30 28 N 10 2579 3400 0 Blue 0
7 AM Fri 31 29 N 10 2579 3400 0 Blue 0
8 AM Fri 34 32 N 10 2579 3400 0 Blue 0
9 AM Fri 37 35 N 10 2579 3400 0 Blue 0
10 AM Fri 40 39 N 7 4518 3400 0 Blue 2
11 AM Fri 42 42 N 7 5232 4495 1095 White 5
12 Noon Fri 44 44 N 7 5661 5661 2261 White 7
1 PM Fri 45 45 N 7 5876 5876 2476 White 8
2 PM Fri 47 46 N 7 6089 6089 2689 White 9
3 PM Fri 47 46 N 7 6089 6089 2689 White 9
4 PM Fri 46 44 NW 5 5661 5661 2261 White 7
5 PM Fri 44 42 NW 5 5232 4495 1095 White 5
6 PM Fri 40 38 NW 5 4140 3400 0 Blue 1
7 PM Fri 37 35 NW 5 2579 3400 0 Blue 0
8 PM Fri 36 34 NW 5 2579 3400 0 Blue 0
9 PM Fri 35 33 NW 5 2579 3400 0 Blue 0
10 PM Fri 35 33 NW 3 2579 3400 0 Blue 0
11 PM Fri 35 33 NW 3 2579 3400 0 Blue 0
12 Midnight Sat 35 33 NW 3 2579 3400 0 Blue 0
1 AM Sat 34 32 NW 3 2579 3400 0 Blue 0
2 AM Sat 34 32 NW 3 2579 3400 0 Blue 0
3 AM Sat 34 32 NW 3 2579 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 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