Detailed Predictions for: St John
Launch Lat, Long, Altitude (f): 39.424433, -122.689342, 6350
LZ Altitude (f): 1185
Sounding

Station:

KOAK

Date/Time:

14 APR 2024

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 Sun 40 40 S 4 5 9877 9877 3527 White 13
1 AM Sun 40 40 S 4 5 9877 9877 3527 White 13
2 AM Sun 40 40 S 3 4 9877 9877 3527 White 13
3 AM Sun 40 40 S 4 6 9877 9877 3527 White 13
4 AM Sun 40 40 S 6 7 9877 9877 3527 White 13
5 AM Sun 40 40 SSW 3 4 9877 9877 3527 White 13
6 AM Sun 44 44 N 2 5 10732 10732 4382 White 17
7 AM Sun 40 40 S 4 6 9877 9877 3527 White 13
8 AM Sun 40 40 S 4 5 9877 9877 3527 White 13
9 AM Sun 41 41 S 4 4 10091 10091 3741 White 14
10 AM Sun 42 42 S 3 4 10306 10306 3956 White 15
11 AM Sun 43 43 S 2 2 10520 10520 4170 White 16
12 Noon Sun 44 44 S 2 3 10732 10732 4382 White 17
1 PM Sun 44 44 SSE 2 3 10732 10732 4382 White 17
2 PM Sun 45 45 SSE 2 3 10945 10945 4595 White 18
3 PM Sun 45 45 SE 2 2 10945 10945 4595 White 18
4 PM Sun 45 45 ESE 2 2 10945 10945 4595 White 18
5 PM Sun 44 44 ENE 3 3 10732 10732 4382 White 17
6 PM Sun 44 44 NE 4 5 10732 10732 4382 White 17
7 PM Sun 43 43 NE 4 5 10520 10520 4170 White 16
8 PM Sun 42 42 NNE 4 5 10306 10306 3956 White 15
9 PM Sun 42 42 NNE 4 4 10306 10306 3956 White 15
10 PM Sun 42 42 NNW 2 3 10306 10306 3956 White 15
11 PM Sun 41 41 N 1 2 10091 10091 3741 White 14
12 Midnight Mon 42 42 N 1 2 10306 10306 3956 White 15
1 AM Mon 41 41 N 0 1 10091 10091 3741 White 14
2 AM Mon 40 40 W 2 3 9877 9877 3527 White 13
3 AM Mon 38 38 W 1 2 9423 9423 3073 White 11
4 AM Mon 37 37 W 1 2 9205 9205 2855 White 10
5 AM Mon 36 36 W 2 4 8988 8988 2638 White 9
6 AM Mon 37 37 W 3 6 9205 9205 2855 White 10
7 AM Mon 40 40 W 2 6 9877 9877 3527 White 13
8 AM Mon 43 43 WNW 0 1 10520 10520 4170 White 16
9 AM Mon 47 48 NNE 0 0 11579 11579 5229 White 21
10 AM Mon 50 52 E 0 1 12415 12415 6065 White 25
11 AM Mon 54 58 E 3 3 13653 13653 7303 White 30
12 Noon Mon 56 61 E 4 5 14264 14264 7914 White 33
1 PM Mon 58 63 E 6 7 14664 14664 8314 White 35
2 PM Mon 60 65 E 6 7 15065 15065 8715 White 37
3 PM Mon 60 65 E 6 7 15065 15065 8715 White 37
4 PM Mon 60 63 E 6 7 14664 14664 8314 White 35
5 PM Mon 59 60 ENE 5 6 14061 14061 7711 White 32
6 PM Mon 57 57 ENE 5 6 13448 13448 7098 White 29
7 PM Mon 52 52 ENE 2 2 12415 12415 6065 White 25
8 PM Mon 49 49 W 2 4 11788 11788 5438 White 22
9 PM Mon 48 48 W 3 7 11579 11579 5229 White 21
10 PM Mon 47 47 W 4 8 11368 11368 5018 White 20
11 PM Mon 46 46 W 4 8 11157 11157 4807 White 19
12 Midnight Tue 46 46 W 3 8 11157 11157 4807 White 19
1 AM Tue 46 46 WNW 3 6 11157 11157 4807 White 19
2 AM Tue 45 45 WNW 3 6 10945 10945 4595 White 18
3 AM Tue 45 45 W 3 7 10945 10945 4595 White 18
4 AM Tue 45 45 W 3 7 10945 10945 4595 White 18
5 AM Tue 45 45 W 3 8 10945 10945 4595 White 18
6 AM Tue 45 45 WNW 2 6 10945 10945 4595 White 18
7 AM Tue 48 48 W 3 7 11579 11579 5229 White 21
8 AM Tue 53 53 W 2 3 12622 12622 6272 White 26
9 AM Tue 58 60 E 1 1 14061 14061 7711 White 32
10 AM Tue 61 64 E 3 3 14865 14865 8515 White 36
11 AM Tue 63 68 E 4 5 15661 15661 9311 White 40
12 Noon Tue 65 71 E 5 6 16248 16248 9898 White 43
1 PM Tue 67 73 E 5 6 16637 16637 10287 White 45
2 PM Tue 67 73 E 6 7 16637 16637 10287 White 45
3 PM Tue 68 73 E 6 7 16637 16637 10287 White 45
4 PM Tue 66 69 E 5 6 15858 15858 9508 White 41
5 PM Tue 65 67 E 4 4 15464 15464 9114 White 39
6 PM Tue 62 62 ESE 3 3 14463 14463 8113 White 34
7 PM Tue 58 58 E 2 3 13653 13653 7303 White 30
8 PM Tue 55 55 SW 2 4 13036 13036 6686 White 28
9 PM Tue 54 54 W 3 7 12829 12829 6479 White 27
10 PM Tue 53 53 W 3 7 12622 12622 6272 White 26
11 PM Tue 52 52 W 3 7 12415 12415 6065 White 25

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]