Detailed Predictions for: Mt Vaca
Launch Lat, Long, Altitude (f): 38.400316, -122.106135, 2821
LZ Altitude (f): 2000
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 Tue 74 74 N 2 9 3683 2821 0 Blue 1
1 AM Tue 75 75 N 2 6 3843 2821 0 Blue 2
2 AM Tue 76 76 NNE 2 8 3919 2821 0 Blue 3
3 AM Tue 74 74 NNE 2 8 3683 2821 0 Blue 1
4 AM Tue 75 75 NE 2 8 3843 2821 0 Blue 2
5 AM Tue 74 74 NE 5 11 3683 2821 0 Blue 1
6 AM Tue 74 74 NE 5 11 3683 2821 0 Blue 1
7 AM Tue 72 72 NE 5 12 2244 2821 0 Blue 0
8 AM Tue 72 72 NE 6 13 2244 2821 0 Blue 0
9 AM Tue 76 77 NE 8 12 4109 3643 822 Blue 4
10 AM Tue 78 80 ENE 5 11 4717 4093 1272 Blue 7
11 AM Tue 79 83 E 5 10 5033 4710 1889 Blue 10
12 Noon Tue 81 86 E 4 9 5737 5028 2207 Blue 13
1 PM Tue 83 89 SE 3 9 7085 5683 2862 Blue 16
2 PM Tue 84 89 S 4 10 7085 5683 2862 Blue 16
3 PM Tue 85 89 SSW 4 11 7085 5683 2862 Blue 16
4 PM Tue 85 88 SW 3 11 6803 5149 2328 Blue 15
5 PM Tue 84 85 WSW 3 11 5179 4928 2107 Blue 12
6 PM Tue 83 83 WSW 2 11 5033 4710 1889 Blue 10
7 PM Tue 80 80 WSW 2 10 4717 4093 1272 Blue 7
8 PM Tue 74 74 WSW 3 11 3683 2821 0 Blue 1
9 PM Tue 75 75 W 4 11 3843 2821 0 Blue 2
10 PM Tue 76 76 W 4 11 3919 2821 0 Blue 3
11 PM Tue 76 76 W 4 11 3919 2821 0 Blue 3
12 Midnight Wed 77 77 WNW 4 11 4109 3643 822 Blue 4
1 AM Wed 76 76 W 3 11 3919 2821 0 Blue 3
2 AM Wed 76 76 W 3 10 3919 2821 0 Blue 3
3 AM Wed 75 75 W 3 10 3843 2821 0 Blue 2
4 AM Wed 74 74 W 4 11 3683 2821 0 Blue 1
5 AM Wed 73 73 W 5 11 2244 2821 0 Blue 0
6 AM Wed 74 74 W 5 11 3683 2821 0 Blue 1
7 AM Wed 70 70 W 5 12 2244 2821 0 Blue 0
8 AM Wed 70 70 W 5 11 2244 2821 0 Blue 0
9 AM Wed 74 75 W 5 13 3843 2821 0 Blue 2
10 AM Wed 74 76 WSW 6 10 3919 2821 0 Blue 3
11 AM Wed 75 78 WSW 6 13 4461 3840 1019 Blue 5
12 Noon Wed 75 79 WSW 6 13 4607 3916 1095 Blue 6
1 PM Wed 76 81 WSW 6 13 4826 4440 1619 Blue 8
2 PM Wed 76 81 WSW 8 16 4826 4440 1619 Blue 8
3 PM Wed 76 80 WSW 8 16 4717 4093 1272 Blue 7
4 PM Wed 76 79 WSW 8 16 4607 3916 1095 Blue 6
5 PM Wed 75 76 WSW 6 16 3919 2821 0 Blue 3
6 PM Wed 73 73 WSW 6 16 2244 2821 0 Blue 0
7 PM Wed 70 70 WSW 6 16 2244 2821 0 Blue 0
8 PM Wed 68 68 W 4 11 2244 2821 0 Blue 0
9 PM Wed 68 68 W 4 11 2244 2821 0 Blue 0
10 PM Wed 69 69 W 4 11 2244 2821 0 Blue 0
11 PM Wed 70 70 WSW 3 10 2244 2821 0 Blue 0
12 Midnight Thu 71 71 WSW 3 10 2244 2821 0 Blue 0
1 AM Thu 72 72 WSW 3 10 2244 2821 0 Blue 0
2 AM Thu 72 72 W 2 8 2244 2821 0 Blue 0
3 AM Thu 73 73 W 2 8 2244 2821 0 Blue 0
4 AM Thu 73 73 W 2 8 2244 2821 0 Blue 0
5 AM Thu 73 73 NW 4 10 2244 2821 0 Blue 0
6 AM Thu 73 73 NW 4 10 2244 2821 0 Blue 0
7 AM Thu 73 73 NW 4 10 2244 2821 0 Blue 0
8 AM Thu 73 73 NNW 5 11 2244 2821 0 Blue 0
9 AM Thu 75 76 NNW 5 11 3919 2821 0 Blue 3
10 AM Thu 78 80 NNW 5 11 4717 4093 1272 Blue 7
11 AM Thu 80 83 N 8 16 5033 4710 1889 Blue 10
12 Noon Thu 81 85 N 8 16 5179 4928 2107 Blue 12
1 PM Thu 82 87 N 8 16 6278 5089 2268 Blue 14
2 PM Thu 83 87 N 5 12 6278 5089 2268 Blue 14
3 PM Thu 84 88 N 5 12 6803 5149 2328 Blue 15
4 PM Thu 84 86 N 5 12 5737 5028 2207 Blue 13
5 PM Thu 84 85 NW 4 12 5179 4928 2107 Blue 12
6 PM Thu 82 82 NW 4 12 4936 4600 1779 Blue 9
7 PM Thu 80 80 NW 4 12 4717 4093 1272 Blue 7
8 PM Thu 79 79 W 3 10 4607 3916 1095 Blue 6
9 PM Thu 78 78 W 3 10 4461 3840 1019 Blue 5
10 PM Thu 78 78 W 3 10 4461 3840 1019 Blue 5
11 PM Thu 78 78 W 3 10 4461 3840 1019 Blue 5
12 Midnight Fri 78 78 W 3 10 4461 3840 1019 Blue 5
1 AM Fri 78 78 W 3 10 4461 3840 1019 Blue 5
2 AM Fri 78 78 W 2 9 4461 3840 1019 Blue 5
3 AM Fri 78 78 W 2 9 4461 3840 1019 Blue 5
4 AM Fri 77 77 W 2 9 4109 3643 822 Blue 4
5 AM Fri 76 76 WNW 3 9 3919 2821 0 Blue 3
6 AM Fri 74 74 WNW 3 9 3683 2821 0 Blue 1
7 AM Fri 74 74 WNW 3 9 3683 2821 0 Blue 1
8 AM Fri 73 73 NNW 3 9 2244 2821 0 Blue 0
9 AM Fri 75 76 NNW 3 9 3919 2821 0 Blue 3
10 AM Fri 76 78 NNW 3 9 4461 3840 1019 Blue 5
11 AM Fri 78 82 N 2 9 4936 4600 1779 Blue 9
12 Noon Fri 80 85 N 2 9 5179 4928 2107 Blue 12
1 PM Fri 82 87 N 2 9 6278 5089 2268 Blue 14
2 PM Fri 82 87 SW 4 10 6278 5089 2268 Blue 14
3 PM Fri 83 87 SW 4 10 6278 5089 2268 Blue 14
4 PM Fri 82 84 SW 4 10 5093 4819 1998 Blue 11
5 PM Fri 81 82 WSW 5 13 4936 4600 1779 Blue 9
6 PM Fri 79 79 WSW 5 13 4607 3916 1095 Blue 6
7 PM Fri 78 78 WSW 5 13 4461 3840 1019 Blue 5
8 PM Fri 76 76 WSW 5 11 3919 2821 0 Blue 3
9 PM Fri 74 74 WSW 5 11 3683 2821 0 Blue 1
10 PM Fri 73 73 WSW 5 11 2244 2821 0 Blue 0
11 PM Fri 72 72 WSW 4 11 2244 2821 0 Blue 0
12 Midnight Sat 72 72 WSW 4 11 2244 2821 0 Blue 0
1 AM Sat 72 72 WSW 4 11 2244 2821 0 Blue 0
2 AM Sat 73 73 W 3 9 2244 2821 0 Blue 0
3 AM Sat 72 72 W 3 9 2244 2821 0 Blue 0
4 AM Sat 72 72 W 3 9 2244 2821 0 Blue 0
5 AM Sat 71 71 WSW 3 9 2244 2821 0 Blue 0
6 AM Sat 70 70 WSW 3 9 2244 2821 0 Blue 0
7 AM Sat 70 70 WSW 3 9 2244 2821 0 Blue 0
8 AM Sat 70 70 WSW 3 8 2244 2821 0 Blue 0
9 AM Sat 71 72 WSW 3 8 2244 2821 0 Blue 0
10 AM Sat 73 75 WSW 3 8 3843 2821 0 Blue 2
11 AM Sat 74 78 SW 3 9 4461 3840 1019 Blue 5
12 Noon Sat 76 81 SW 3 9 4826 4440 1619 Blue 8
1 PM Sat 77 82 SW 3 9 4936 4600 1779 Blue 9
2 PM Sat 77 82 SW 5 12 4936 4600 1779 Blue 9
3 PM Sat 77 81 SW 5 12 4826 4440 1619 Blue 8
4 PM Sat 76 79 SW 5 12 4607 3916 1095 Blue 6
5 PM Sat 74 75 WSW 5 16 3843 2821 0 Blue 2
6 PM Sat 72 72 WSW 5 16 2244 2821 0 Blue 0
7 PM Sat 69 69 WSW 5 16 2244 2821 0 Blue 0
8 PM Sat 67 67 WSW 5 14 2244 2821 0 Blue 0
9 PM Sat 67 67 WSW 5 14 2244 2821 0 Blue 0
10 PM Sat 68 68 WSW 5 14 2244 2821 0 Blue 0
11 PM Sat 70 70 WSW 5 13 2244 2821 0 Blue 0
12 Midnight Sun 70 70 WSW 5 13 2244 2821 0 Blue 0
1 AM Sun 70 70 WSW 5 13 2244 2821 0 Blue 0
2 AM Sun 71 71 WSW 4 11 2244 2821 0 Blue 0
3 AM Sun 71 71 WSW 4 11 2244 2821 0 Blue 0
4 AM Sun 70 70 WSW 4 11 2244 2821 0 Blue 0
5 AM Sun 70 70 WSW 4 10 2244 2821 0 Blue 0
6 AM Sun 69 69 WSW 4 10 2244 2821 0 Blue 0
7 AM Sun 68 68 WSW 4 10 2244 2821 0 Blue 0
8 AM Sun 67 67 WSW 4 9 2244 2821 0 Blue 0
9 AM Sun 68 69 WSW 4 9 2244 2821 0 Blue 0
10 AM Sun 70 72 WSW 4 9 2244 2821 0 Blue 0
11 AM Sun 71 74 SW 4 9 3683 2821 0 Blue 1
12 Noon Sun 72 76 SW 4 9 3919 2821 0 Blue 3
1 PM Sun 73 78 SW 4 9 4461 3840 1019 Blue 5
2 PM Sun 73 78 SW 6 11 4461 3840 1019 Blue 5
3 PM Sun 73 77 SW 6 11 4109 3643 822 Blue 4
4 PM Sun 72 74 SW 6 11 3683 2821 0 Blue 1
5 PM Sun 71 72 SW 5 13 2244 2821 0 Blue 0
6 PM Sun 68 68 SW 5 13 2244 2821 0 Blue 0
7 PM Sun 66 66 SW 5 13 2244 2821 0 Blue 0
8 PM Sun 64 64 WSW 5 13 2244 2821 0 Blue 0
9 PM Sun 64 64 WSW 5 13 2244 2821 0 Blue 0
10 PM Sun 66 66 WSW 5 13 2244 2821 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]