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

Station:

KVBG

Date/Time:

26 MAY 2019

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 44 44 NW 1 6190 5272 772 White 6
6 AM Sun 44 44 N 2 6190 5272 772 White 6
7 AM Sun 46 46 N 5 6371 6188 1688 Blue 8
8 AM Sun 49 49 S 1 6800 6367 1867 Blue 11
9 AM Sun 53 54 E 2 7596 7146 2646 Blue 16
10 AM Sun 56 58 SE 3 8241 7724 3224 Blue 20
11 AM Sun 58 61 S 6 8751 8220 3720 Blue 23
12 Noon Sun 58 62 S 9 9067 8385 3885 Blue 24
1 PM Sun 59 63 S 13 9590 8550 4050 Blue 25
2 PM Sun 58 61 S 14 8751 8220 3720 Blue 23
3 PM Sun 58 60 SW 14 8573 8055 3555 Blue 22
4 PM Sun 58 59 W 16 8407 7890 3390 Blue 21
5 PM Sun 56 56 W 17 7909 7447 2947 Blue 18
6 PM Sun 54 54 W 18 7596 7146 2646 Blue 16
7 PM Sun 52 52 W 9 7325 6788 2288 Blue 14
8 PM Sun 49 49 N 10 6800 6367 1867 Blue 11
9 PM Sun 47 47 N 12 6502 6247 1747 Blue 9
10 PM Sun 46 46 N 8 6371 6188 1688 Blue 8
11 PM Sun 45 45 N 6 6311 5395 895 Blue 7
12 Midnight Mon 44 44 N 3 6190 5272 772 White 6
1 AM Mon 43 43 N 3 5968 5152 652 White 5
2 AM Mon 43 43 N 6 5968 5152 652 White 5
3 AM Mon 42 42 N 6 5414 5032 532 Blue 4
4 AM Mon 40 40 N 2 5155 4500 0 Blue 2
5 AM Mon 41 41 NW 3 5275 4659 159 Blue 3
6 AM Mon 40 40 N 2 5155 4500 0 Blue 2
7 AM Mon 41 41 N 3 5275 4659 159 Blue 3
8 AM Mon 46 46 N 5 6371 6188 1688 Blue 8
9 AM Mon 50 51 N 3 7162 6640 2140 Blue 13
10 AM Mon 53 55 NW 2 7742 7312 2812 Blue 17
11 AM Mon 56 60 NW 6 8573 8055 3555 Blue 22
12 Noon Mon 58 62 NW 8 9067 8385 3885 Blue 24
1 PM Mon 60 64 NW 8 10169 8725 4225 Blue 26
2 PM Mon 62 66 NW 8 10999 9502 5002 White 28
3 PM Mon 64 67 NW 8 11211 10054 5554 White 29
4 PM Mon 65 67 NW 7 11211 10054 5554 White 29
5 PM Mon 65 66 NW 7 10999 9502 5002 White 28
6 PM Mon 64 64 NW 7 10169 8725 4225 Blue 26
7 PM Mon 62 62 NW 8 9067 8385 3885 Blue 24
8 PM Mon 60 60 NW 8 8573 8055 3555 Blue 22
9 PM Mon 58 58 NW 8 8241 7724 3224 Blue 20
10 PM Mon 56 56 NW 8 7909 7447 2947 Blue 18
11 PM Mon 54 54 NW 8 7596 7146 2646 Blue 16
12 Midnight Tue 52 52 NW 8 7325 6788 2288 Blue 14
1 AM Tue 50 50 NW 8 6981 6491 1991 Blue 12
2 AM Tue 49 49 NW 8 6800 6367 1867 Blue 11
3 AM Tue 47 47 NW 7 6502 6247 1747 Blue 9
4 AM Tue 46 46 NW 7 6371 6188 1688 Blue 8
5 AM Tue 46 46 NW 7 6371 6188 1688 Blue 8
6 AM Tue 47 47 NW 8 6502 6247 1747 Blue 9
7 AM Tue 48 48 NW 10 6651 6307 1807 Blue 10
8 AM Tue 51 52 NW 12 7325 6788 2288 Blue 14
9 AM Tue 54 56 NW 13 7909 7447 2947 Blue 18
10 AM Tue 58 61 N 14 8751 8220 3720 Blue 23
11 AM Tue 62 67 N 14 11211 10054 5554 White 29
12 Noon Tue 65 71 N 14 12050 12050 7550 White 33
1 PM Tue 67 73 N 13 12464 12464 7964 White 35
2 PM Tue 68 74 N 13 12671 12671 8171 White 36
3 PM Tue 69 74 N 14 12671 12671 8171 White 36
4 PM Tue 70 73 N 15 12464 12464 7964 White 35
5 PM Tue 70 72 N 15 12257 12257 7757 White 34
6 PM Tue 68 68 N 13 11423 10389 5889 White 30
7 PM Tue 66 66 N 10 10999 9502 5002 White 28
8 PM Tue 63 63 N 8 9590 8550 4050 Blue 25
9 PM Tue 61 61 NW 7 8751 8220 3720 Blue 23
10 PM Tue 59 59 NW 7 8407 7890 3390 Blue 21
11 PM Tue 57 57 NW 7 8075 7581 3081 Blue 19
12 Midnight Wed 55 55 W 7 7742 7312 2812 Blue 17
1 AM Wed 53 53 W 7 7460 6966 2466 Blue 15
2 AM Wed 51 51 W 7 7162 6640 2140 Blue 13
3 AM Wed 49 49 NW 6 6800 6367 1867 Blue 11
4 AM Wed 47 47 NW 5 6502 6247 1747 Blue 9
5 AM Wed 47 47 NW 3 6502 6247 1747 Blue 9
6 AM Wed 48 48 NW 3 6651 6307 1807 Blue 10
7 AM Wed 51 51 NW 3 7162 6640 2140 Blue 13
8 AM Wed 54 55 NW 3 7742 7312 2812 Blue 17
9 AM Wed 58 60 NW 3 8573 8055 3555 Blue 22
10 AM Wed 62 66 NW 3 10999 9502 5002 White 28
11 AM Wed 66 71 NW 3 12050 12050 7550 White 33
12 Noon Wed 69 74 W 5 12671 12671 8171 White 36
1 PM Wed 71 76 S 5 13084 13084 8584 White 38
2 PM Wed 72 77 SE 6 13290 13290 8790 White 39
3 PM Wed 73 76 S 6 13084 13084 8584 White 38
4 PM Wed 74 76 S 7 13084 13084 8584 White 38
5 PM Wed 73 74 SW 7 12671 12671 8171 White 36
6 PM Wed 71 71 SW 7 12050 12050 7550 White 33
7 PM Wed 69 69 W 7 11633 11038 6538 White 31
8 PM Wed 66 66 W 7 10999 9502 5002 White 28
9 PM Wed 64 64 W 7 10169 8725 4225 Blue 26
10 PM Wed 61 61 W 6 8751 8220 3720 Blue 23
11 PM Wed 59 59 W 6 8407 7890 3390 Blue 21
12 Midnight Thu 57 57 W 6 8075 7581 3081 Blue 19
1 AM Thu 55 55 W 5 7742 7312 2812 Blue 17
2 AM Thu 53 53 W 5 7460 6966 2466 Blue 15
3 AM Thu 51 51 W 5 7162 6640 2140 Blue 13
4 AM Thu 49 49 W 3 6800 6367 1867 Blue 11
5 AM Thu 49 49 W 3 6800 6367 1867 Blue 11
6 AM Thu 51 51 W 2 7162 6640 2140 Blue 13
7 AM Thu 53 53 SW 2 7460 6966 2466 Blue 15
8 AM Thu 57 58 SW 2 8241 7724 3224 Blue 20
9 AM Thu 61 63 SW 3 9590 8550 4050 Blue 25
10 AM Thu 65 69 S 5 11633 11038 6538 White 31
11 AM Thu 69 74 S 6 12671 12671 8171 White 36
12 Noon Thu 71 77 S 5 13290 13290 8790 White 39
1 PM Thu 73 79 SW 2 13701 13701 9201 White 41
2 PM Thu 74 79 W 1 13701 13701 9201 White 41
3 PM Thu 75 79 W 2 13701 13701 9201 White 41
4 PM Thu 75 78 SW 5 13495 13495 8995 White 40
5 PM Thu 74 75 SW 7 12878 12878 8378 White 37
6 PM Thu 72 72 SW 7 12257 12257 7757 White 34
7 PM Thu 70 70 W 7 11842 11766 7266 White 32
8 PM Thu 67 67 W 6 11211 10054 5554 White 29
9 PM Thu 65 65 W 6 10442 8986 4486 Blue 27
10 PM Thu 62 62 W 6 9067 8385 3885 Blue 24
11 PM Thu 60 60 W 6 8573 8055 3555 Blue 22
12 Midnight Fri 58 58 W 6 8241 7724 3224 Blue 20
1 AM Fri 56 56 W 5 7909 7447 2947 Blue 18
2 AM Fri 54 54 W 5 7596 7146 2646 Blue 16
3 AM Fri 52 52 W 5 7325 6788 2288 Blue 14
4 AM Fri 50 50 W 3 6981 6491 1991 Blue 12
5 AM Fri 50 50 W 3 6981 6491 1991 Blue 12
6 AM Fri 52 52 NW 3 7325 6788 2288 Blue 14
7 AM Fri 54 54 N 3 7596 7146 2646 Blue 16
8 AM Fri 58 59 N 3 8407 7890 3390 Blue 21
9 AM Fri 62 64 N 3 10169 8725 4225 Blue 26
10 AM Fri 66 70 NE 3 11842 11766 7266 White 32
11 AM Fri 69 74 E 5 12671 12671 8171 White 36
12 Noon Fri 72 78 E 6 13495 13495 8995 White 40
1 PM Fri 74 80 S 7 13904 13904 9404 White 42
2 PM Fri 75 80 S 8 13904 13904 9404 White 42
3 PM Fri 76 79 S 8 13701 13701 9201 White 41
4 PM Fri 76 78 SW 8 13495 13495 8995 White 40
5 PM Fri 75 76 W 7 13084 13084 8584 White 38
6 PM Fri 74 74 W 7 12671 12671 8171 White 36
7 PM Fri 72 72 W 6 12257 12257 7757 White 34
8 PM Fri 70 70 W 6 11842 11766 7266 White 32
9 PM Fri 67 67 W 6 11211 10054 5554 White 29
10 PM Fri 65 65 NW 6 10442 8986 4486 Blue 27
11 PM Fri 62 62 NW 6 9067 8385 3885 Blue 24
12 Midnight Sat 60 60 NW 6 8573 8055 3555 Blue 22
1 AM Sat 58 58 NW 5 8241 7724 3224 Blue 20
2 AM Sat 56 56 W 5 7909 7447 2947 Blue 18
3 AM Sat 54 54 W 5 7596 7146 2646 Blue 16
4 AM Sat 52 52 W 3 7325 6788 2288 Blue 14

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