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

Station:

KVBG

Date/Time:

12 MAY 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 Wed 61 61 NNW 11 16 4295 4500 0 Blue 0
1 AM Wed 60 60 NW 10 14 4295 4500 0 Blue 0
2 AM Wed 57 57 WNW 8 11 4295 4500 0 Blue 0
3 AM Wed 56 56 WNW 6 9 4295 4500 0 Blue 0
4 AM Wed 54 54 NW 6 9 4295 4500 0 Blue 0
5 AM Wed 53 53 NW 6 9 4295 4500 0 Blue 0
6 AM Wed 52 52 NW 5 8 4295 4500 0 Blue 0
7 AM Wed 56 56 NNW 4 6 4295 4500 0 Blue 0
8 AM Wed 63 64 NNW 4 6 4295 4500 0 Blue 0
9 AM Wed 69 72 NNE 5 8 8139 5186 686 Blue 3
10 AM Wed 73 78 ESE 6 9 10668 8666 4166 Blue 9
11 AM Wed 78 85 SSE 8 11 14552 13550 9050 Blue 16
12 Noon Wed 80 88 SSE 9 12 15591 14435 9935 Blue 19
1 PM Wed 83 91 SE 10 14 18111 15454 10954 White 22
2 PM Wed 84 91 SE 11 16 18111 15454 10954 White 22
3 PM Wed 86 91 SSE 11 16 18111 15454 10954 White 22
4 PM Wed 86 89 S 11 16 16122 14779 10279 Blue 20
5 PM Wed 87 89 S 11 16 16122 14779 10279 Blue 20
6 PM Wed 85 85 SSW 10 14 14552 13550 9050 Blue 16
7 PM Wed 82 82 W 8 11 13628 11356 6856 Blue 13
8 PM Wed 77 77 WNW 6 9 9905 8489 3989 Blue 8
9 PM Wed 73 73 WNW 9 12 8334 6271 1771 Blue 4
10 PM Wed 70 70 NW 11 16 6332 4500 0 Blue 1
11 PM Wed 67 67 NW 12 17 4295 4500 0 Blue 0
12 Midnight Thu 64 64 NW 11 16 4295 4500 0 Blue 0
1 AM Thu 62 62 WNW 10 14 4295 4500 0 Blue 0
2 AM Thu 60 60 WNW 9 12 4295 4500 0 Blue 0
3 AM Thu 58 58 WNW 9 12 4295 4500 0 Blue 0
4 AM Thu 56 56 WNW 8 11 4295 4500 0 Blue 0
5 AM Thu 55 55 WNW 8 11 4295 4500 0 Blue 0
6 AM Thu 57 57 NW 6 9 4295 4500 0 Blue 0
7 AM Thu 61 61 NNW 6 9 4295 4500 0 Blue 0
8 AM Thu 66 67 N 5 8 4295 4500 0 Blue 0
9 AM Thu 71 74 NNE 5 8 8512 7232 2732 Blue 5
10 AM Thu 76 81 E 4 6 13154 10485 5985 Blue 12
11 AM Thu 80 86 SE 5 8 14899 13803 9303 Blue 17
12 Noon Thu 83 90 SE 5 8 16635 15119 10619 Blue 21
1 PM Thu 85 91 SSE 5 8 18111 15454 10954 White 22
2 PM Thu 86 91 SSE 6 9 18111 15454 10954 White 22
3 PM Thu 87 91 S 6 9 18111 15454 10954 White 22
4 PM Thu 88 90 WSW 6 9 16635 15119 10619 Blue 21
5 PM Thu 87 88 W 8 11 15591 14435 9935 Blue 19
6 PM Thu 84 84 W 9 12 14201 12901 8401 Blue 15
7 PM Thu 81 81 W 11 16 13154 10485 5985 Blue 12
8 PM Thu 77 77 W 12 17 9905 8489 3989 Blue 8
9 PM Thu 74 74 W 10 14 8512 7232 2732 Blue 5
10 PM Thu 71 71 WNW 9 12 7315 4500 0 Blue 2
11 PM Thu 68 68 NW 6 9 4295 4500 0 Blue 0
12 Midnight Fri 65 65 NW 6 9 4295 4500 0 Blue 0
1 AM Fri 63 63 WNW 6 9 4295 4500 0 Blue 0
2 AM Fri 61 61 WNW 8 11 4295 4500 0 Blue 0
3 AM Fri 58 58 WNW 8 11 4295 4500 0 Blue 0
4 AM Fri 56 56 WNW 8 11 4295 4500 0 Blue 0
5 AM Fri 55 55 WNW 8 11 4295 4500 0 Blue 0
6 AM Fri 57 57 WNW 6 9 4295 4500 0 Blue 0
7 AM Fri 61 61 NW 6 9 4295 4500 0 Blue 0
8 AM Fri 66 67 NW 5 8 4295 4500 0 Blue 0
9 AM Fri 71 74 W 5 8 8512 7232 2732 Blue 5
10 AM Fri 76 81 SSW 5 8 13154 10485 5985 Blue 12
11 AM Fri 80 87 S 5 8 15241 14087 9587 Blue 18
12 Noon Fri 83 90 S 5 8 16635 15119 10619 Blue 21
1 PM Fri 85 92 S 6 9 18312 15918 11418 White 23
2 PM Fri 86 92 S 8 11 18312 15918 11418 White 23
3 PM Fri 87 92 S 11 16 18312 15918 11418 White 23
4 PM Fri 86 89 SW 14 20 16122 14779 10279 Blue 20
5 PM Fri 85 86 WSW 17 24 14899 13803 9303 Blue 17
6 PM Fri 82 82 WSW 17 24 13628 11356 6856 Blue 13
7 PM Fri 79 79 WSW 14 20 11548 8843 4343 Blue 10
8 PM Fri 75 75 WSW 12 17 8690 8084 3584 Blue 6
9 PM Fri 72 72 W 11 16 8139 5186 686 Blue 3
10 PM Fri 68 68 NW 10 14 4295 4500 0 Blue 0
11 PM Fri 65 65 NNW 9 12 4295 4500 0 Blue 0
12 Midnight Sat 62 62 NNW 8 11 4295 4500 0 Blue 0
1 AM Sat 60 60 NNW 8 11 4295 4500 0 Blue 0
2 AM Sat 58 58 NNW 8 11 4295 4500 0 Blue 0
3 AM Sat 56 56 NNW 6 9 4295 4500 0 Blue 0
4 AM Sat 54 54 NNW 6 9 4295 4500 0 Blue 0
5 AM Sat 54 54 NNW 6 9 4295 4500 0 Blue 0
6 AM Sat 55 55 NNW 5 8 4295 4500 0 Blue 0
7 AM Sat 58 58 NNW 5 8 4295 4500 0 Blue 0
8 AM Sat 61 62 NNW 5 8 4295 4500 0 Blue 0
9 AM Sat 65 67 WNW 5 8 4295 4500 0 Blue 0
10 AM Sat 69 72 SW 5 8 8139 5186 686 Blue 3
11 AM Sat 73 77 S 6 9 9905 8489 3989 Blue 8
12 Noon Sat 75 80 SSW 8 11 12353 9797 5297 Blue 11
1 PM Sat 76 80 SW 10 14 12353 9797 5297 Blue 11
2 PM Sat 76 79 WSW 11 16 11548 8843 4343 Blue 10
3 PM Sat 76 78 WSW 12 17 10668 8666 4166 Blue 9
4 PM Sat 76 77 W 13 19 9905 8489 3989 Blue 8
5 PM Sat 75 75 W 14 20 8690 8084 3584 Blue 6
6 PM Sat 73 73 W 16 23 8334 6271 1771 Blue 4
7 PM Sat 69 69 WNW 16 23 5215 4500 0 Blue 0
8 PM Sat 66 66 WNW 14 20 4295 4500 0 Blue 0
9 PM Sat 63 63 WNW 12 17 4295 4500 0 Blue 0
10 PM Sat 61 61 WNW 10 14 4295 4500 0 Blue 0
11 PM Sat 59 59 WNW 9 12 4295 4500 0 Blue 0
12 Midnight Sun 57 57 WNW 8 11 4295 4500 0 Blue 0
1 AM Sun 56 56 WNW 8 11 4295 4500 0 Blue 0
2 AM Sun 55 55 WNW 9 12 4295 4500 0 Blue 0
3 AM Sun 53 53 NW 9 12 4295 4500 0 Blue 0
4 AM Sun 52 52 NW 9 12 4295 4500 0 Blue 0
5 AM Sun 51 51 NW 9 12 4295 4500 0 Blue 0
6 AM Sun 52 52 NW 9 12 4295 4500 0 Blue 0
7 AM Sun 54 54 NNW 8 11 4295 4500 0 Blue 0
8 AM Sun 57 58 NNW 8 11 4295 4500 0 Blue 0
9 AM Sun 61 63 NNW 6 9 4295 4500 0 Blue 0
10 AM Sun 66 70 N 6 9 6332 4500 0 Blue 1
11 AM Sun 70 74 N 6 9 8512 7232 2732 Blue 5
12 Noon Sun 72 77 N 8 11 9905 8489 3989 Blue 8
1 PM Sun 73 78 NNE 9 12 10668 8666 4166 Blue 9
2 PM Sun 74 78 NNE 11 16 10668 8666 4166 Blue 9
3 PM Sun 75 78 N 12 17 10668 8666 4166 Blue 9
4 PM Sun 76 78 N 12 17 10668 8666 4166 Blue 9
5 PM Sun 75 76 N 12 17 8958 8312 3812 Blue 7
6 PM Sun 73 73 N 12 17 8334 6271 1771 Blue 4
7 PM Sun 70 70 NNW 12 17 6332 4500 0 Blue 1
8 PM Sun 67 67 NNW 11 16 4295 4500 0 Blue 0
9 PM Sun 65 65 NW 10 14 4295 4500 0 Blue 0
10 PM Sun 63 63 WNW 9 12 4295 4500 0 Blue 0
11 PM Sun 61 61 WNW 8 11 4295 4500 0 Blue 0
12 Midnight Mon 59 59 WNW 8 11 4295 4500 0 Blue 0
1 AM Mon 58 58 WNW 8 11 4295 4500 0 Blue 0
2 AM Mon 56 56 WNW 8 11 4295 4500 0 Blue 0
3 AM Mon 54 54 WNW 8 11 4295 4500 0 Blue 0
4 AM Mon 52 52 WNW 8 11 4295 4500 0 Blue 0
5 AM Mon 51 51 WNW 8 11 4295 4500 0 Blue 0
6 AM Mon 53 53 WNW 8 11 4295 4500 0 Blue 0
7 AM Mon 56 56 NW 6 9 4295 4500 0 Blue 0
8 AM Mon 60 61 NW 6 9 4295 4500 0 Blue 0
9 AM Mon 65 68 NW 5 8 4295 4500 0 Blue 0
10 AM Mon 70 74 NNW 5 8 8512 7232 2732 Blue 5
11 AM Mon 75 81 NNW 6 9 13154 10485 5985 Blue 12
12 Noon Mon 78 85 NW 8 11 14552 13550 9050 Blue 16
1 PM Mon 79 86 W 9 12 14899 13803 9303 Blue 17
2 PM Mon 80 86 WSW 10 14 14899 13803 9303 Blue 17
3 PM Mon 81 85 WSW 11 16 14552 13550 9050 Blue 16
4 PM Mon 81 84 WSW 12 17 14201 12901 8401 Blue 15
5 PM Mon 80 81 WSW 12 17 13154 10485 5985 Blue 12
6 PM Mon 78 78 WSW 12 17 10668 8666 4166 Blue 9
7 PM Mon 74 74 W 11 16 8512 7232 2732 Blue 5
8 PM Mon 71 71 W 10 14 7315 4500 0 Blue 2
9 PM Mon 68 68 W 9 12 4295 4500 0 Blue 0
10 PM Mon 66 66 W 8 11 4295 4500 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 ac_soaring@yahoo.com