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

Station:

KVBG

Date/Time:

16 JUL 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 Tue 60 60 W 3 3678 4500 0 Blue 0
6 AM Tue 58 58 W 3 3678 4500 0 Blue 0
7 AM Tue 62 62 W 3 3678 4500 0 Blue 0
8 AM Tue 70 71 NW 3 3678 4500 0 Blue 0
9 AM Tue 78 81 W 3 6031 4563 63 Blue 2
10 AM Tue 84 89 SW 3 11291 8408 3908 Blue 10
11 AM Tue 88 95 S 3 13320 11773 7273 Blue 16
12 Noon Tue 92 100 S 3 15538 14177 9677 Blue 21
1 PM Tue 94 103 S 3 16032 15394 10894 Blue 24
2 PM Tue 97 105 SE 3 16304 15845 11345 Blue 26
3 PM Tue 99 106 S 5 16440 15980 11480 Blue 27
4 PM Tue 99 104 SW 6 16168 15710 11210 Blue 25
5 PM Tue 99 102 SW 7 15896 14996 10496 Blue 23
6 PM Tue 97 98 W 8 14728 13166 8666 Blue 19
7 PM Tue 94 94 W 8 12771 11600 7100 Blue 15
8 PM Tue 88 88 NW 9 10833 7949 3449 Blue 9
9 PM Tue 83 83 NW 8 7039 5490 990 Blue 4
10 PM Tue 80 80 NW 7 5507 4500 0 Blue 1
11 PM Tue 76 76 NW 6 3721 4500 0 Blue 0
12 Midnight Wed 73 73 NW 5 3678 4500 0 Blue 0
1 AM Wed 71 71 W 5 3678 4500 0 Blue 0
2 AM Wed 66 66 W 3 3678 4500 0 Blue 0
3 AM Wed 63 63 W 3 3678 4500 0 Blue 0
4 AM Wed 61 61 W 3 3678 4500 0 Blue 0
5 AM Wed 59 59 W 3 3678 4500 0 Blue 0
6 AM Wed 58 58 W 3 3678 4500 0 Blue 0
7 AM Wed 65 65 W 3 3678 4500 0 Blue 0
8 AM Wed 71 72 NW 3 3678 4500 0 Blue 0
9 AM Wed 78 81 W 3 6031 4563 63 Blue 2
10 AM Wed 82 87 SW 3 9636 7479 2979 Blue 8
11 AM Wed 87 94 S 3 12771 11600 7100 Blue 15
12 Noon Wed 90 98 S 5 14728 13166 8666 Blue 19
1 PM Wed 93 101 SE 6 15760 14590 10090 Blue 22
2 PM Wed 95 102 SE 8 15896 14996 10496 Blue 23
3 PM Wed 97 103 SE 9 16032 15394 10894 Blue 24
4 PM Wed 98 102 SE 10 15896 14996 10496 Blue 23
5 PM Wed 98 100 SE 10 15538 14177 9677 Blue 21
6 PM Wed 96 97 S 9 14311 12623 8123 Blue 18
7 PM Wed 92 92 S 7 11813 11253 6753 Blue 13
8 PM Wed 88 88 S 5 10833 7949 3449 Blue 9
9 PM Wed 84 84 S 5 7525 6006 1506 Blue 5
10 PM Wed 80 80 SW 5 5507 4500 0 Blue 1
11 PM Wed 77 77 W 5 4147 4500 0 Blue 0
12 Midnight Thu 74 74 W 5 3678 4500 0 Blue 0
1 AM Thu 70 70 W 3 3678 4500 0 Blue 0
2 AM Thu 67 67 W 3 3678 4500 0 Blue 0
3 AM Thu 63 63 W 3 3678 4500 0 Blue 0
4 AM Thu 61 61 SW 3 3678 4500 0 Blue 0
5 AM Thu 60 60 SW 3 3678 4500 0 Blue 0
6 AM Thu 62 62 SW 3 3678 4500 0 Blue 0
7 AM Thu 66 66 W 3 3678 4500 0 Blue 0
8 AM Thu 72 73 W 3 3678 4500 0 Blue 0
9 AM Thu 77 79 SW 3 4978 4500 0 Blue 0
10 AM Thu 82 85 S 3 8000 6509 2009 Blue 6
11 AM Thu 87 92 SE 3 11813 11253 6753 Blue 13
12 Noon Thu 91 97 SE 5 14311 12623 8123 Blue 18
1 PM Thu 94 100 SE 7 15538 14177 9677 Blue 21
2 PM Thu 96 101 S 8 15760 14590 10090 Blue 22
3 PM Thu 98 103 S 9 16032 15394 10894 Blue 24
4 PM Thu 99 102 S 10 15896 14996 10496 Blue 23
5 PM Thu 98 100 S 10 15538 14177 9677 Blue 21
6 PM Thu 96 97 S 9 14311 12623 8123 Blue 18
7 PM Thu 92 92 S 8 11813 11253 6753 Blue 13
8 PM Thu 87 87 S 7 9636 7479 2979 Blue 8
9 PM Thu 84 84 S 6 7525 6006 1506 Blue 5
10 PM Thu 80 80 S 5 5507 4500 0 Blue 1
11 PM Thu 76 76 SW 3 3721 4500 0 Blue 0
12 Midnight Fri 72 72 SW 3 3678 4500 0 Blue 0
1 AM Fri 68 68 W 3 3678 4500 0 Blue 0
2 AM Fri 64 64 NW 3 3678 4500 0 Blue 0
3 AM Fri 61 61 NW 3 3678 4500 0 Blue 0
4 AM Fri 58 58 NW 3 3678 4500 0 Blue 0
5 AM Fri 58 58 W 3 3678 4500 0 Blue 0
6 AM Fri 60 60 W 3 3678 4500 0 Blue 0
7 AM Fri 64 64 W 3 3678 4500 0 Blue 0
8 AM Fri 70 71 W 3 3678 4500 0 Blue 0
9 AM Fri 76 79 SW 3 4978 4500 0 Blue 0
10 AM Fri 82 87 S 3 9636 7479 2979 Blue 8
11 AM Fri 87 93 S 3 12202 11427 6927 Blue 14
12 Noon Fri 91 99 S 5 15136 13693 9193 Blue 20
1 PM Fri 93 101 S 6 15760 14590 10090 Blue 22
2 PM Fri 95 102 S 7 15896 14996 10496 Blue 23
3 PM Fri 97 103 S 9 16032 15394 10894 Blue 24
4 PM Fri 98 102 S 10 15896 14996 10496 Blue 23
5 PM Fri 98 100 S 12 15538 14177 9677 Blue 21
6 PM Fri 96 97 S 10 14311 12623 8123 Blue 18
7 PM Fri 92 92 S 9 11813 11253 6753 Blue 13
8 PM Fri 88 88 S 7 10833 7949 3449 Blue 9
9 PM Fri 84 84 S 6 7525 6006 1506 Blue 5
10 PM Fri 80 80 W 6 5507 4500 0 Blue 1
11 PM Fri 76 76 W 6 3721 4500 0 Blue 0
12 Midnight Sat 72 72 W 6 3678 4500 0 Blue 0
1 AM Sat 69 69 W 5 3678 4500 0 Blue 0
2 AM Sat 65 65 W 5 3678 4500 0 Blue 0
3 AM Sat 61 61 W 5 3678 4500 0 Blue 0
4 AM Sat 59 59 W 5 3678 4500 0 Blue 0
5 AM Sat 58 58 W 5 3678 4500 0 Blue 0
6 AM Sat 60 60 W 5 3678 4500 0 Blue 0
7 AM Sat 65 65 W 5 3678 4500 0 Blue 0
8 AM Sat 71 72 W 5 3678 4500 0 Blue 0
9 AM Sat 77 79 W 5 4978 4500 0 Blue 0
10 AM Sat 82 86 S 3 8465 7000 2500 Blue 7
11 AM Sat 86 91 S 3 11640 10600 6100 Blue 12
12 Noon Sat 89 95 S 3 13320 11773 7273 Blue 16
1 PM Sat 91 97 S 3 14311 12623 8123 Blue 18
2 PM Sat 93 99 S 3 15136 13693 9193 Blue 20
3 PM Sat 95 100 S 5 15538 14177 9677 Blue 21
4 PM Sat 97 101 S 6 15760 14590 10090 Blue 22
5 PM Sat 97 99 S 7 15136 13693 9193 Blue 20
6 PM Sat 94 95 S 7 13320 11773 7273 Blue 16
7 PM Sat 90 90 S 6 11466 9434 4934 Blue 11
8 PM Sat 86 86 S 5 8465 7000 2500 Blue 7
9 PM Sat 82 82 S 5 6542 4971 471 Blue 3
10 PM Sat 79 79 S 5 4978 4500 0 Blue 0
11 PM Sat 76 76 S 5 3721 4500 0 Blue 0
12 Midnight Sun 73 73 SW 5 3678 4500 0 Blue 0
1 AM Sun 69 69 W 3 3678 4500 0 Blue 0
2 AM Sun 64 64 W 3 3678 4500 0 Blue 0
3 AM Sun 60 60 W 3 3678 4500 0 Blue 0
4 AM Sun 57 57 SW 3 3678 4500 0 Blue 0
5 AM Sun 57 57 SW 3 3678 4500 0 Blue 0
6 AM Sun 60 60 SW 3 3678 4500 0 Blue 0
7 AM Sun 64 64 SW 3 3678 4500 0 Blue 0
8 AM Sun 70 71 SW 3 3678 4500 0 Blue 0
9 AM Sun 76 79 S 5 4978 4500 0 Blue 0
10 AM Sun 81 86 S 6 8465 7000 2500 Blue 7
11 AM Sun 86 92 SE 7 11813 11253 6753 Blue 13
12 Noon Sun 89 96 SE 8 13850 12060 7560 Blue 17
1 PM Sun 92 100 SE 10 15538 14177 9677 Blue 21
2 PM Sun 94 101 SE 12 15760 14590 10090 Blue 22
3 PM Sun 96 102 SE 13 15896 14996 10496 Blue 23
4 PM Sun 97 101 S 13 15760 14590 10090 Blue 22
5 PM Sun 96 99 S 13 15136 13693 9193 Blue 20
6 PM Sun 94 95 S 14 13320 11773 7273 Blue 16
7 PM Sun 90 90 S 14 11466 9434 4934 Blue 11
8 PM Sun 86 86 S 13 8465 7000 2500 Blue 7
9 PM Sun 82 82 S 10 6542 4971 471 Blue 3
10 PM Sun 79 79 S 6 4978 4500 0 Blue 0
11 PM Sun 75 75 SW 3 3678 4500 0 Blue 0
12 Midnight Mon 72 72 SW 2 3678 4500 0 Blue 0
1 AM Mon 69 69 SW 3 3678 4500 0 Blue 0
2 AM Mon 65 65 W 3 3678 4500 0 Blue 0
3 AM Mon 61 61 SW 3 3678 4500 0 Blue 0
4 AM Mon 59 59 SW 3 3678 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