Detailed Predictions for: Chalk Bluffs
Launch Altitude (f): 4500
LZ Altitude (f): 4220
Sounding

Station:

KVBG

Date/Time:

22 JUL 2018

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)
5 AM Sun 67 67 NW 6 4298 4500 0 Blue 0
6 AM Sun 69 69 NW 6 4493 4500 0 Blue 0
7 AM Sun 71 71 NW 6 5164 4500 0 Blue 2
8 AM Sun 74 74 NW 6 5997 5158 658 Blue 5
9 AM Sun 78 79 NW 5 7953 6898 2398 Blue 10
10 AM Sun 83 84 NE 5 9760 8578 4078 Blue 15
11 AM Sun 87 88 NE 3 12337 10458 5958 Blue 19
12 Noon Sun 91 92 N 2 14339 12720 8220 Blue 23
1 PM Sun 93 94 NW 2 14988 13710 9210 White 25
2 PM Sun 95 96 W 2 15399 14650 10150 White 27
3 PM Sun 95 96 W 3 15399 14650 10150 White 27
4 PM Sun 94 95 W 6 15195 14186 9686 White 26
5 PM Sun 92 92 W 7 14339 12720 8220 Blue 23
6 PM Sun 89 89 W 7 12859 11099 6599 Blue 20
7 PM Sun 86 86 W 7 11236 9228 4728 Blue 17
8 PM Sun 83 83 NW 7 9278 8249 3749 Blue 14
9 PM Sun 80 80 NW 7 8289 7240 2740 Blue 11
10 PM Sun 77 77 NW 6 7271 5983 1483 Blue 8
11 PM Sun 74 74 W 6 5997 5158 658 Blue 5
12 Midnight Mon 71 71 W 5 5164 4500 0 Blue 2
1 AM Mon 68 68 W 3 4298 4500 0 Blue 0
2 AM Mon 66 66 W 3 4298 4500 0 Blue 0
3 AM Mon 64 64 W 5 4298 4500 0 Blue 0
4 AM Mon 64 64 W 5 4298 4500 0 Blue 0
5 AM Mon 65 65 W 6 4298 4500 0 Blue 0
6 AM Mon 67 67 W 6 4298 4500 0 Blue 0
7 AM Mon 71 71 W 5 5164 4500 0 Blue 2
8 AM Mon 76 76 W 3 6925 5710 1210 Blue 7
9 AM Mon 80 81 SW 3 8622 7580 3080 Blue 12
10 AM Mon 85 87 S 3 11797 9609 5109 Blue 18
11 AM Mon 89 92 S 3 14339 12720 8220 Blue 23
12 Noon Mon 93 96 S 3 15399 14650 10150 White 27
1 PM Mon 96 99 SW 3 16012 15928 11428 White 30
2 PM Mon 98 101 SW 3 16414 16414 11914 White 32
3 PM Mon 99 102 SW 5 16615 16615 12115 White 33
4 PM Mon 99 101 W 6 16414 16414 11914 White 32
5 PM Mon 97 98 W 7 15808 15521 11021 White 29
6 PM Mon 94 94 W 7 14988 13710 9210 White 25
7 PM Mon 90 90 W 6 13366 11668 7168 Blue 21
8 PM Mon 86 86 W 6 11236 9228 4728 Blue 17
9 PM Mon 81 81 W 6 8622 7580 3080 Blue 12
10 PM Mon 76 76 W 7 6925 5710 1210 Blue 7
11 PM Mon 72 72 W 7 5443 4500 0 Blue 3
12 Midnight Tue 69 69 W 7 4493 4500 0 Blue 0
1 AM Tue 66 66 W 6 4298 4500 0 Blue 0
2 AM Tue 64 64 W 6 4298 4500 0 Blue 0
3 AM Tue 64 64 W 6 4298 4500 0 Blue 0
4 AM Tue 65 65 W 5 4298 4500 0 Blue 0
5 AM Tue 67 67 W 5 4298 4500 0 Blue 0
6 AM Tue 71 71 W 5 5164 4500 0 Blue 2
7 AM Tue 75 75 SW 3 6475 5435 935 Blue 6
8 AM Tue 80 80 SW 3 8289 7240 2740 Blue 11
9 AM Tue 84 85 SW 3 10586 8905 4405 Blue 16
10 AM Tue 89 91 S 3 13859 12202 7702 Blue 22
11 AM Tue 93 96 S 3 15399 14650 10150 White 27
12 Noon Tue 97 101 S 3 16414 16414 11914 White 32
1 PM Tue 99 103 S 3 16814 16814 12314 White 34
2 PM Tue 101 105 SW 3 17214 17214 12714 White 36
3 PM Tue 101 104 SW 5 17014 17014 12514 White 35
4 PM Tue 100 102 SW 6 16615 16615 12115 White 33
5 PM Tue 98 99 SW 7 16012 15928 11428 White 30
6 PM Tue 95 95 SW 7 15195 14186 9686 White 26
7 PM Tue 91 91 SW 6 13859 12202 7702 Blue 22
8 PM Tue 86 86 W 6 11236 9228 4728 Blue 17
9 PM Tue 82 82 W 6 8951 7916 3416 Blue 13
10 PM Tue 78 78 W 6 7614 6445 1945 Blue 9
11 PM Tue 74 74 W 6 5997 5158 658 Blue 5
12 Midnight Wed 71 71 W 6 5164 4500 0 Blue 2
1 AM Wed 68 68 W 5 4298 4500 0 Blue 0
2 AM Wed 66 66 W 5 4298 4500 0 Blue 0
3 AM Wed 66 66 W 5 4298 4500 0 Blue 0
4 AM Wed 67 67 W 5 4298 4500 0 Blue 0
5 AM Wed 69 69 W 5 4493 4500 0 Blue 0
6 AM Wed 73 73 W 5 5721 4852 352 Blue 4
7 AM Wed 77 77 W 3 7271 5983 1483 Blue 8
8 AM Wed 82 83 W 2 9278 8249 3749 Blue 14
9 AM Wed 87 89 SW 2 12859 11099 6599 Blue 20
10 AM Wed 92 95 SW 1 15195 14186 9686 White 26
11 AM Wed 96 100 SW 1 16213 16213 11713 White 31
12 Noon Wed 100 105 SW 1 17214 17214 12714 White 36
1 PM Wed 102 107 SW 2 17612 17612 13112 White 38
2 PM Wed 104 109 W 2 18005 18005 13505 White 40
3 PM Wed 104 108 W 3 17809 17809 13309 White 39
4 PM Wed 103 106 W 5 17413 17413 12913 White 37
5 PM Wed 101 103 W 5 16814 16814 12314 White 34
6 PM Wed 97 98 W 5 15808 15521 11021 White 29
7 PM Wed 93 93 W 5 14780 13222 8722 White 24
8 PM Wed 88 88 W 5 12337 10458 5958 Blue 19
9 PM Wed 83 83 W 3 9278 8249 3749 Blue 14
10 PM Wed 78 78 W 3 7614 6445 1945 Blue 9
11 PM Wed 73 73 W 3 5721 4852 352 Blue 4
12 Midnight Thu 70 70 W 3 4857 4500 0 Blue 1
1 AM Thu 67 67 W 3 4298 4500 0 Blue 0
2 AM Thu 66 66 W 5 4298 4500 0 Blue 0
3 AM Thu 66 66 W 5 4298 4500 0 Blue 0
4 AM Thu 67 67 W 5 4298 4500 0 Blue 0
5 AM Thu 69 69 W 5 4493 4500 0 Blue 0
6 AM Thu 72 72 W 3 5443 4500 0 Blue 3
7 AM Thu 76 76 W 3 6925 5710 1210 Blue 7
8 AM Thu 81 82 W 2 8951 7916 3416 Blue 13
9 AM Thu 86 88 W 1 12337 10458 5958 Blue 19
10 AM Thu 90 93 W 0 14780 13222 8722 White 24
11 AM Thu 94 99 W 0 16012 15928 11428 White 30
12 Noon Thu 98 103 W 0 16814 16814 12314 White 34
1 PM Thu 100 106 W 1 17413 17413 12913 White 37
2 PM Thu 102 107 W 2 17612 17612 13112 White 38
3 PM Thu 102 106 SW 2 17413 17413 12913 White 37
4 PM Thu 101 104 SW 3 17014 17014 12514 White 35
5 PM Thu 100 102 SW 5 16615 16615 12115 White 33
6 PM Thu 97 98 SW 5 15808 15521 11021 White 29
7 PM Thu 93 93 SW 6 14780 13222 8722 White 24
8 PM Thu 88 88 W 6 12337 10458 5958 Blue 19
9 PM Thu 84 84 W 6 9760 8578 4078 Blue 15
10 PM Thu 79 79 W 6 7953 6898 2398 Blue 10
11 PM Thu 75 75 W 6 6475 5435 935 Blue 6
12 Midnight Fri 72 72 W 6 5443 4500 0 Blue 3
1 AM Fri 69 69 W 5 4493 4500 0 Blue 0
2 AM Fri 68 68 W 5 4298 4500 0 Blue 0
3 AM Fri 67 67 W 5 4298 4500 0 Blue 0
4 AM Fri 67 67 W 3 4298 4500 0 Blue 0
5 AM Fri 69 69 W 3 4493 4500 0 Blue 0
6 AM Fri 72 72 W 3 5443 4500 0 Blue 3
7 AM Fri 76 76 SW 3 6925 5710 1210 Blue 7
8 AM Fri 80 81 SW 3 8622 7580 3080 Blue 12
9 AM Fri 85 88 S 3 12337 10458 5958 Blue 19
10 AM Fri 89 93 S 3 14780 13222 8722 White 24
11 AM Fri 94 100 S 3 16213 16213 11713 White 31
12 Noon Fri 98 105 S 3 17214 17214 12714 White 36
1 PM Fri 101 109 S 3 18005 18005 13505 White 40
2 PM Fri 103 111 S 5 18397 18397 13897 White 42
3 PM Fri 104 110 S 5 18202 18202 13702 White 41
4 PM Fri 104 109 S 5 18005 18005 13505 White 40
5 PM Fri 102 105 S 5 17214 17214 12714 White 36
6 PM Fri 98 99 S 5 16012 15928 11428 White 30
7 PM Fri 94 94 SW 5 14988 13710 9210 White 25
8 PM Fri 88 88 SW 5 12337 10458 5958 Blue 19
9 PM Fri 82 82 W 5 8951 7916 3416 Blue 13
10 PM Fri 77 77 W 5 7271 5983 1483 Blue 8
11 PM Fri 72 72 NW 5 5443 4500 0 Blue 3
12 Midnight Sat 68 68 NW 5 4298 4500 0 Blue 0
1 AM Sat 66 66 W 5 4298 4500 0 Blue 0
2 AM Sat 64 64 W 3 4298 4500 0 Blue 0
3 AM Sat 64 64 W 3 4298 4500 0 Blue 0
4 AM Sat 65 65 W 3 4298 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 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