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

Station:

KVBG

Date/Time:

16 SEP 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 45 45 NW 2 3888 4500 0 Blue 0
6 AM Sun 45 45 NW 1 3888 4500 0 Blue 0
7 AM Sun 48 48 N 1 3888 4500 0 Blue 0
8 AM Sun 53 53 N 1 3888 4500 0 Blue 0
9 AM Sun 61 62 N 2 3888 4500 0 Blue 0
10 AM Sun 70 73 E 3 7611 5660 1160 Blue 9
11 AM Sun 78 83 SE 5 11030 10257 5757 Blue 19
12 Noon Sun 83 89 SE 7 13939 12415 7915 Blue 25
1 PM Sun 87 93 SE 9 15662 14239 9739 Blue 29
2 PM Sun 89 94 SE 12 16026 14671 10171 Blue 30
3 PM Sun 90 94 SE 12 16026 14671 10171 Blue 30
4 PM Sun 90 93 S 12 15662 14239 9739 Blue 29
5 PM Sun 88 89 S 10 13939 12415 7915 Blue 25
6 PM Sun 82 82 SW 9 10731 10052 5552 Blue 18
7 PM Sun 75 75 W 8 8890 6870 2370 Blue 11
8 PM Sun 69 69 NW 7 5520 5077 577 Blue 5
9 PM Sun 65 65 NW 6 4934 4500 0 Blue 1
10 PM Sun 62 62 NW 6 3888 4500 0 Blue 0
11 PM Sun 59 59 NW 5 3888 4500 0 Blue 0
12 Midnight Mon 56 56 NW 5 3888 4500 0 Blue 0
1 AM Mon 53 53 NW 3 3888 4500 0 Blue 0
2 AM Mon 50 50 NW 3 3888 4500 0 Blue 0
3 AM Mon 48 48 NW 3 3888 4500 0 Blue 0
4 AM Mon 46 46 NW 3 3888 4500 0 Blue 0
5 AM Mon 45 45 NW 3 3888 4500 0 Blue 0
6 AM Mon 46 46 N 3 3888 4500 0 Blue 0
7 AM Mon 49 49 N 2 3888 4500 0 Blue 0
8 AM Mon 54 54 N 2 3888 4500 0 Blue 0
9 AM Mon 62 63 NE 2 3888 4500 0 Blue 0
10 AM Mon 71 74 SE 2 8265 6158 1658 Blue 10
11 AM Mon 79 83 S 2 11030 10257 5757 Blue 19
12 Noon Mon 85 91 SE 3 14818 13349 8849 Blue 27
1 PM Mon 88 94 SE 6 16026 14671 10171 Blue 30
2 PM Mon 90 95 SE 8 16386 15093 10593 Blue 31
3 PM Mon 91 95 SE 10 16386 15093 10593 Blue 31
4 PM Mon 91 94 SE 12 16026 14671 10171 Blue 30
5 PM Mon 89 90 SE 12 14383 12888 8388 Blue 26
6 PM Mon 83 83 S 10 11030 10257 5757 Blue 19
7 PM Mon 77 77 W 8 9685 8188 3688 Blue 13
8 PM Mon 71 71 NW 6 6199 5369 869 Blue 7
9 PM Mon 67 67 NW 5 5227 4500 0 Blue 3
10 PM Mon 64 64 W 5 4420 4500 0 Blue 0
11 PM Mon 62 62 W 5 3888 4500 0 Blue 0
12 Midnight Tue 59 59 W 5 3888 4500 0 Blue 0
1 AM Tue 56 56 NW 5 3888 4500 0 Blue 0
2 AM Tue 53 53 NW 5 3888 4500 0 Blue 0
3 AM Tue 50 50 NW 5 3888 4500 0 Blue 0
4 AM Tue 48 48 NW 3 3888 4500 0 Blue 0
5 AM Tue 47 47 NW 3 3888 4500 0 Blue 0
6 AM Tue 48 48 W 2 3888 4500 0 Blue 0
7 AM Tue 52 52 W 2 3888 4500 0 Blue 0
8 AM Tue 57 57 SW 1 3888 4500 0 Blue 0
9 AM Tue 65 66 SW 1 5081 4500 0 Blue 2
10 AM Tue 74 77 SW 1 9685 8188 3688 Blue 13
11 AM Tue 81 85 SW 1 12052 10687 6187 Blue 21
12 Noon Tue 86 92 SW 0 15244 13799 9299 Blue 28
1 PM Tue 88 94 S 0 16026 14671 10171 Blue 30
2 PM Tue 89 94 S 0 16026 14671 10171 Blue 30
3 PM Tue 90 94 S 2 16026 14671 10171 Blue 30
4 PM Tue 90 93 W 6 15662 14239 9739 Blue 29
5 PM Tue 88 89 W 8 13939 12415 7915 Blue 25
6 PM Tue 83 83 NW 8 11030 10257 5757 Blue 19
7 PM Tue 77 77 NW 7 9685 8188 3688 Blue 13
8 PM Tue 71 71 NW 6 6199 5369 869 Blue 7
9 PM Tue 67 67 NW 6 5227 4500 0 Blue 3
10 PM Tue 64 64 W 6 4420 4500 0 Blue 0
11 PM Tue 61 61 W 6 3888 4500 0 Blue 0
12 Midnight Wed 58 58 W 6 3888 4500 0 Blue 0
1 AM Wed 55 55 W 5 3888 4500 0 Blue 0
2 AM Wed 52 52 W 5 3888 4500 0 Blue 0
3 AM Wed 49 49 W 5 3888 4500 0 Blue 0
4 AM Wed 48 48 NW 3 3888 4500 0 Blue 0
5 AM Wed 48 48 NW 3 3888 4500 0 Blue 0
6 AM Wed 51 51 NW 3 3888 4500 0 Blue 0
7 AM Wed 55 55 NW 3 3888 4500 0 Blue 0
8 AM Wed 60 60 N 5 3888 4500 0 Blue 0
9 AM Wed 66 67 N 5 5227 4500 0 Blue 3
10 AM Wed 72 75 N 6 8890 6870 2370 Blue 11
11 AM Wed 77 81 N 6 10515 9852 5352 Blue 17
12 Noon Wed 81 86 N 6 12542 10919 6419 Blue 22
1 PM Wed 84 90 N 6 14383 12888 8388 Blue 26
2 PM Wed 86 91 N 6 14818 13349 8849 Blue 27
3 PM Wed 87 91 NW 6 14818 13349 8849 Blue 27
4 PM Wed 87 90 NW 6 14383 12888 8388 Blue 26
5 PM Wed 85 86 NW 6 12542 10919 6419 Blue 22
6 PM Wed 83 83 NW 6 11030 10257 5757 Blue 19
7 PM Wed 79 79 NW 6 10088 9395 4895 Blue 15
8 PM Wed 75 75 NW 6 8890 6870 2370 Blue 11
9 PM Wed 71 71 NW 6 6199 5369 869 Blue 7
10 PM Wed 66 66 NW 6 5081 4500 0 Blue 2
11 PM Wed 60 60 NW 6 3888 4500 0 Blue 0
12 Midnight Thu 56 56 NW 6 3888 4500 0 Blue 0
1 AM Thu 51 51 NW 5 3888 4500 0 Blue 0
2 AM Thu 47 47 W 5 3888 4500 0 Blue 0
3 AM Thu 45 45 W 5 3888 4500 0 Blue 0
4 AM Thu 44 44 W 3 3888 4500 0 Blue 0
5 AM Thu 45 45 W 3 3888 4500 0 Blue 0
6 AM Thu 48 48 W 3 3888 4500 0 Blue 0
7 AM Thu 53 53 SW 2 3888 4500 0 Blue 0
8 AM Thu 59 59 SW 2 3888 4500 0 Blue 0
9 AM Thu 66 67 S 2 5227 4500 0 Blue 3
10 AM Thu 73 76 SE 2 9482 7545 3045 Blue 12
11 AM Thu 79 83 SE 2 11030 10257 5757 Blue 19
12 Noon Thu 84 89 SE 3 13939 12415 7915 Blue 25
1 PM Thu 87 93 SE 5 15662 14239 9739 Blue 29
2 PM Thu 90 95 SE 6 16386 15093 10593 Blue 31
3 PM Thu 91 95 S 7 16386 15093 10593 Blue 31
4 PM Thu 91 94 S 8 16026 14671 10171 Blue 30
5 PM Thu 89 90 S 8 14383 12888 8388 Blue 26
6 PM Thu 87 87 S 8 13019 11432 6932 Blue 23
7 PM Thu 83 83 S 7 11030 10257 5757 Blue 19
8 PM Thu 78 78 S 6 9887 8804 4304 Blue 14
9 PM Thu 73 73 S 6 7611 5660 1160 Blue 9
10 PM Thu 67 67 SW 5 5227 4500 0 Blue 3
11 PM Thu 62 62 SW 3 3888 4500 0 Blue 0
12 Midnight Fri 57 57 SW 3 3888 4500 0 Blue 0
1 AM Fri 52 52 SW 2 3888 4500 0 Blue 0
2 AM Fri 49 49 W 2 3888 4500 0 Blue 0
3 AM Fri 47 47 W 2 3888 4500 0 Blue 0
4 AM Fri 46 46 W 2 3888 4500 0 Blue 0
5 AM Fri 47 47 W 2 3888 4500 0 Blue 0
6 AM Fri 51 51 W 2 3888 4500 0 Blue 0
7 AM Fri 56 56 SW 2 3888 4500 0 Blue 0
8 AM Fri 62 62 SW 2 3888 4500 0 Blue 0
9 AM Fri 68 69 S 2 5520 5077 577 Blue 5
10 AM Fri 74 77 SE 2 9685 8188 3688 Blue 13
11 AM Fri 80 84 SE 2 11549 10472 5972 Blue 20
12 Noon Fri 84 89 SE 3 13939 12415 7915 Blue 25
1 PM Fri 88 94 S 3 16026 14671 10171 Blue 30
2 PM Fri 89 94 S 5 16026 14671 10171 Blue 30
3 PM Fri 90 94 S 6 16026 14671 10171 Blue 30
4 PM Fri 89 92 SW 7 15244 13799 9299 Blue 28
5 PM Fri 88 89 SW 7 13939 12415 7915 Blue 25
6 PM Fri 85 85 SW 7 12052 10687 6187 Blue 21
7 PM Fri 81 81 SW 7 10515 9852 5352 Blue 17
8 PM Fri 77 77 W 6 9685 8188 3688 Blue 13
9 PM Fri 72 72 W 6 6925 5515 1015 Blue 8
10 PM Fri 68 68 W 5 5373 4932 432 Blue 4
11 PM Fri 63 63 W 5 3888 4500 0 Blue 0
12 Midnight Sat 58 58 W 5 3888 4500 0 Blue 0
1 AM Sat 54 54 W 3 3888 4500 0 Blue 0
2 AM Sat 51 51 W 3 3888 4500 0 Blue 0
3 AM Sat 49 49 W 3 3888 4500 0 Blue 0
4 AM Sat 48 48 W 2 3888 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