Detailed Predictions for: Chalk Bluffs
Launch Lat, Long, Altitude (f): 37.416328, -118.442829, 4500
LZ Altitude (f): 4220
Sounding

Station:

KVBG

Date/Time:

15 JUN 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 68 68 WNW 10 14 4072 4500 0 Blue 0
1 AM Tue 64 64 NW 9 13 4072 4500 0 Blue 0
2 AM Tue 63 63 NW 9 12 4072 4500 0 Blue 0
3 AM Tue 60 60 NW 9 12 4072 4500 0 Blue 0
4 AM Tue 58 58 NW 8 11 4072 4500 0 Blue 0
5 AM Tue 56 56 NW 8 11 4072 4500 0 Blue 0
6 AM Tue 56 56 NW 6 10 4072 4500 0 Blue 0
7 AM Tue 62 62 NW 5 9 4072 4500 0 Blue 0
8 AM Tue 73 74 NW 5 8 6093 4500 0 Blue 2
9 AM Tue 80 83 W 5 8 10504 10037 5537 Blue 11
10 AM Tue 85 90 S 6 9 12530 11165 6665 Blue 18
11 AM Tue 91 98 SSE 9 12 17037 14110 9610 Blue 26
12 Noon Tue 94 102 SSE 11 17 21196 17467 12967 White 30
1 PM Tue 98 106 S 14 23 21958 21958 17458 White 34
2 PM Tue 101 109 SSW 17 26 22527 22527 18027 White 37
3 PM Tue 102 108 SSW 18 27 22338 22338 17838 White 36
4 PM Tue 102 106 SW 18 26 21958 21958 17458 White 34
5 PM Tue 102 104 SW 17 26 21578 18838 14338 White 32
6 PM Tue 101 102 WSW 17 25 21196 17467 12967 White 30
7 PM Tue 97 97 W 17 25 16219 13783 9283 Blue 25
8 PM Tue 90 90 WNW 16 24 12530 11165 6665 Blue 18
9 PM Tue 86 86 WNW 14 20 11028 10470 5970 Blue 14
10 PM Tue 82 82 NW 12 17 10340 9739 5239 Blue 10
11 PM Tue 78 78 NW 10 14 8860 6922 2422 Blue 6
12 Midnight Wed 75 75 NW 10 13 6990 4500 0 Blue 3
1 AM Wed 71 71 NW 9 12 4072 4500 0 Blue 0
2 AM Wed 69 69 NW 9 12 4072 4500 0 Blue 0
3 AM Wed 67 67 NW 9 12 4072 4500 0 Blue 0
4 AM Wed 64 64 NW 8 11 4072 4500 0 Blue 0
5 AM Wed 62 62 NW 8 10 4072 4500 0 Blue 0
6 AM Wed 64 64 NW 6 9 4072 4500 0 Blue 0
7 AM Wed 69 69 NNW 5 8 4072 4500 0 Blue 0
8 AM Wed 76 77 NNW 4 6 8313 6046 1546 Blue 5
9 AM Wed 83 85 NNE 5 6 10854 10314 5814 Blue 13
10 AM Wed 89 92 ESE 5 9 13215 11935 7435 Blue 20
11 AM Wed 95 99 SSE 8 11 17792 14980 10480 Blue 27
12 Noon Wed 99 103 S 10 14 21388 18173 13673 White 31
1 PM Wed 101 105 SSW 13 19 21768 21768 17268 White 33
2 PM Wed 103 107 SSW 16 23 22148 22148 17648 White 35
3 PM Wed 104 106 SW 16 23 21958 21958 17458 White 34
4 PM Wed 104 105 SW 16 21 21768 21768 17268 White 33
5 PM Wed 103 103 WSW 14 20 21388 18173 13673 White 31
6 PM Wed 99 99 WSW 13 19 17792 14980 10480 Blue 27
7 PM Wed 95 95 W 13 19 14304 13118 8618 Blue 23
8 PM Wed 91 91 W 12 18 12874 11337 6837 Blue 19
9 PM Wed 87 87 W 12 17 11203 10644 6144 Blue 15
10 PM Wed 84 84 W 11 16 10679 10175 5675 Blue 12
11 PM Wed 81 81 W 10 14 10201 8785 4285 Blue 9
12 Midnight Thu 79 79 W 10 13 9816 7688 3188 Blue 7
1 AM Thu 76 76 WNW 9 12 7748 5081 581 Blue 4
2 AM Thu 73 73 WNW 8 11 5103 4500 0 Blue 1
3 AM Thu 70 70 WNW 8 10 4072 4500 0 Blue 0
4 AM Thu 67 67 WNW 6 10 4072 4500 0 Blue 0
5 AM Thu 67 67 WNW 6 9 4072 4500 0 Blue 0
6 AM Thu 69 69 WNW 6 9 4072 4500 0 Blue 0
7 AM Thu 74 74 W 6 9 6093 4500 0 Blue 2
8 AM Thu 81 82 SW 6 9 10340 9739 5239 Blue 10
9 AM Thu 89 91 SSW 6 9 12874 11337 6837 Blue 19
10 AM Thu 96 99 S 6 10 17792 14980 10480 Blue 27
11 AM Thu 101 105 SSE 8 11 21768 21768 17268 White 33
12 Noon Thu 102 106 S 9 12 21958 21958 17458 White 34
1 PM Thu 101 104 S 10 13 21578 18838 14338 White 32
2 PM Thu 101 103 SSW 11 16 21388 18173 13673 White 31
3 PM Thu 101 102 SW 12 18 21196 17467 12967 White 30
4 PM Thu 102 103 WSW 13 19 21388 18173 13673 White 31
5 PM Thu 102 102 WSW 14 20 21196 17467 12967 White 30
6 PM Thu 100 100 WSW 14 20 18496 15886 11386 Blue 28
7 PM Thu 96 96 W 13 19 15320 13452 8952 Blue 24
8 PM Thu 92 92 W 12 18 13215 11935 7435 Blue 20
9 PM Thu 89 89 W 12 17 12103 10991 6491 Blue 17
10 PM Thu 85 85 W 11 16 10854 10314 5814 Blue 13
11 PM Thu 83 83 W 10 13 10504 10037 5537 Blue 11
12 Midnight Fri 80 80 W 9 12 10062 8246 3746 Blue 8
1 AM Fri 77 77 W 8 11 8313 6046 1546 Blue 5
2 AM Fri 74 74 W 8 10 6093 4500 0 Blue 2
3 AM Fri 71 71 W 6 10 4072 4500 0 Blue 0
4 AM Fri 68 68 W 6 9 4072 4500 0 Blue 0
5 AM Fri 67 67 W 6 9 4072 4500 0 Blue 0
6 AM Fri 70 70 W 5 9 4072 4500 0 Blue 0
7 AM Fri 75 75 WSW 6 9 6990 4500 0 Blue 3
8 AM Fri 81 82 SW 6 9 10340 9739 5239 Blue 10
9 AM Fri 87 89 SSW 6 10 12103 10991 6491 Blue 17
10 AM Fri 93 97 S 8 10 16219 13783 9283 Blue 25
11 AM Fri 97 103 SSE 8 11 21388 18173 13673 White 31
12 Noon Fri 100 106 S 9 12 21958 21958 17458 White 34
1 PM Fri 101 107 S 10 14 22148 22148 17648 White 35
2 PM Fri 101 107 SSW 11 16 22148 22148 17648 White 35
3 PM Fri 101 106 SW 12 18 21958 21958 17458 White 34
4 PM Fri 101 104 WSW 13 19 21578 18838 14338 White 32
5 PM Fri 100 102 WSW 13 19 21196 17467 12967 White 30
6 PM Fri 97 98 WSW 13 19 17037 14110 9610 Blue 26
7 PM Fri 94 94 W 13 18 13885 12781 8281 Blue 22
8 PM Fri 90 90 W 12 17 12530 11165 6665 Blue 18
9 PM Fri 87 87 W 11 16 11203 10644 6144 Blue 15
10 PM Fri 84 84 W 10 14 10679 10175 5675 Blue 12
11 PM Fri 81 81 W 9 13 10201 8785 4285 Blue 9
12 Midnight Sat 77 77 W 9 12 8313 6046 1546 Blue 5
1 AM Sat 74 74 W 9 12 6093 4500 0 Blue 2
2 AM Sat 71 71 W 8 11 4072 4500 0 Blue 0
3 AM Sat 68 68 W 8 11 4072 4500 0 Blue 0
4 AM Sat 65 65 W 8 10 4072 4500 0 Blue 0
5 AM Sat 65 65 W 6 10 4072 4500 0 Blue 0
6 AM Sat 67 67 W 6 9 4072 4500 0 Blue 0
7 AM Sat 72 72 W 5 9 4493 4500 0 Blue 0
8 AM Sat 78 79 WSW 5 8 9816 7688 3188 Blue 7
9 AM Sat 84 87 SW 5 8 11203 10644 6144 Blue 15
10 AM Sat 90 95 SSW 5 8 14304 13118 8618 Blue 23
11 AM Sat 95 102 SSW 6 9 21196 17467 12967 White 30
12 Noon Sat 97 105 SSW 8 11 21768 21768 17268 White 33
1 PM Sat 98 106 SW 10 13 21958 21958 17458 White 34
2 PM Sat 99 106 SW 11 17 21958 21958 17458 White 34
3 PM Sat 100 106 WSW 13 19 21958 21958 17458 White 34
4 PM Sat 101 105 WSW 16 21 21768 21768 17268 White 33
5 PM Sat 100 102 WSW 17 24 21196 17467 12967 White 30
6 PM Sat 98 99 WSW 17 24 17792 14980 10480 Blue 27
7 PM Sat 94 94 W 16 23 13885 12781 8281 Blue 22
8 PM Sat 89 89 W 14 21 12103 10991 6491 Blue 17
9 PM Sat 86 86 W 13 19 11028 10470 5970 Blue 14
10 PM Sat 82 82 W 12 18 10340 9739 5239 Blue 10
11 PM Sat 79 79 W 11 16 9816 7688 3188 Blue 7
12 Midnight Sun 77 77 W 10 14 8313 6046 1546 Blue 5
1 AM Sun 74 74 W 10 13 6093 4500 0 Blue 2
2 AM Sun 71 71 W 9 12 4072 4500 0 Blue 0
3 AM Sun 67 67 W 8 11 4072 4500 0 Blue 0
4 AM Sun 64 64 W 8 10 4072 4500 0 Blue 0
5 AM Sun 64 64 W 6 10 4072 4500 0 Blue 0
6 AM Sun 67 67 W 6 9 4072 4500 0 Blue 0
7 AM Sun 72 72 W 5 9 4493 4500 0 Blue 0
8 AM Sun 79 80 W 5 8 10062 8246 3746 Blue 8
9 AM Sun 85 88 WSW 5 8 11398 10818 6318 Blue 16
10 AM Sun 90 95 WSW 5 8 14304 13118 8618 Blue 23
11 AM Sun 94 101 SW 6 9 19158 16708 12208 Blue 29
12 Noon Sun 97 105 SW 6 10 21768 21768 17268 White 33
1 PM Sun 99 107 SW 8 11 22148 22148 17648 White 35
2 PM Sun 101 109 SW 10 13 22527 22527 18027 White 37
3 PM Sun 102 108 SW 11 16 22338 22338 17838 White 36
4 PM Sun 102 106 SW 12 17 21958 21958 17458 White 34
5 PM Sun 101 103 SW 13 19 21388 18173 13673 White 31
6 PM Sun 98 99 WSW 13 19 17792 14980 10480 Blue 27
7 PM Sun 95 95 WSW 13 19 14304 13118 8618 Blue 23
8 PM Sun 91 91 W 13 19 12874 11337 6837 Blue 19
9 PM Sun 86 86 W 13 18 11028 10470 5970 Blue 14
10 PM Sun 83 83 W 12 17 10504 10037 5537 Blue 11

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 ac_soaring@yahoo.com