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

Station:

KVBG

Date/Time:

13 NOV 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)
4 AM Tue 27 27 N 3 2874 4500 0 Blue 0
5 AM Tue 26 26 N 3 2874 4500 0 Blue 0
6 AM Tue 26 26 N 3 2874 4500 0 Blue 0
7 AM Tue 30 30 N 3 2874 4500 0 Blue 0
8 AM Tue 37 37 N 3 2874 4500 0 Blue 0
9 AM Tue 47 47 E 2 2874 4500 0 Blue 0
10 AM Tue 56 57 SE 2 4613 4500 0 Blue 0
11 AM Tue 62 63 SE 2 6415 5526 1026 Blue 4
12 Noon Tue 65 66 SE 3 7352 6397 1897 Blue 7
1 PM Tue 66 67 SE 3 7680 6683 2183 Blue 8
2 PM Tue 65 65 SE 3 7021 6108 1608 Blue 6
3 PM Tue 63 63 SE 3 6415 5526 1026 Blue 4
4 PM Tue 60 60 SE 2 5536 4611 111 Blue 1
5 PM Tue 55 55 SE 1 3965 4500 0 Blue 0
6 PM Tue 50 50 S 0 2874 4500 0 Blue 0
7 PM Tue 45 45 S 0 2874 4500 0 Blue 0
8 PM Tue 42 42 SW 0 2874 4500 0 Blue 0
9 PM Tue 40 40 NW 1 2874 4500 0 Blue 0
10 PM Tue 39 39 N 2 2874 4500 0 Blue 0
11 PM Tue 38 38 N 2 2874 4500 0 Blue 0
12 Midnight Wed 38 38 NW 2 2874 4500 0 Blue 0
1 AM Wed 36 36 NW 2 2874 4500 0 Blue 0
2 AM Wed 35 35 NW 2 2874 4500 0 Blue 0
3 AM Wed 32 32 N 2 2874 4500 0 Blue 0
4 AM Wed 30 30 N 2 2874 4500 0 Blue 0
5 AM Wed 28 28 N 2 2874 4500 0 Blue 0
6 AM Wed 28 28 N 2 2874 4500 0 Blue 0
7 AM Wed 31 31 N 2 2874 4500 0 Blue 0
8 AM Wed 39 39 N 2 2874 4500 0 Blue 0
9 AM Wed 48 49 NE 1 2874 4500 0 Blue 0
10 AM Wed 57 58 E 1 4933 4500 0 Blue 0
11 AM Wed 63 65 E 1 7021 6108 1608 Blue 6
12 Noon Wed 67 69 E 1 8326 7321 2821 Blue 10
1 PM Wed 68 70 E 1 8645 7646 3146 Blue 11
2 PM Wed 68 69 E 1 8326 7321 2821 Blue 10
3 PM Wed 66 66 SE 2 7352 6397 1897 Blue 7
4 PM Wed 62 62 S 2 6124 5232 732 Blue 3
5 PM Wed 56 56 S 2 4290 4500 0 Blue 0
6 PM Wed 51 51 W 1 2874 4500 0 Blue 0
7 PM Wed 46 46 W 1 2874 4500 0 Blue 0
8 PM Wed 42 42 W 2 2874 4500 0 Blue 0
9 PM Wed 41 41 NW 3 2874 4500 0 Blue 0
10 PM Wed 39 39 NW 5 2874 4500 0 Blue 0
11 PM Wed 38 38 NW 5 2874 4500 0 Blue 0
12 Midnight Thu 36 36 NW 5 2874 4500 0 Blue 0
1 AM Thu 34 34 NW 5 2874 4500 0 Blue 0
2 AM Thu 33 33 NW 5 2874 4500 0 Blue 0
3 AM Thu 31 31 NW 5 2874 4500 0 Blue 0
4 AM Thu 29 29 NW 5 2874 4500 0 Blue 0
5 AM Thu 28 28 N 3 2874 4500 0 Blue 0
6 AM Thu 28 28 N 3 2874 4500 0 Blue 0
7 AM Thu 32 32 N 2 2874 4500 0 Blue 0
8 AM Thu 40 40 N 2 2874 4500 0 Blue 0
9 AM Thu 50 51 NE 2 2874 4500 0 Blue 0
10 AM Thu 59 60 E 2 5536 4611 111 Blue 1
11 AM Thu 65 67 E 2 7680 6683 2183 Blue 8
12 Noon Thu 68 70 E 3 8645 7646 3146 Blue 11
1 PM Thu 69 71 E 3 8961 7967 3467 Blue 12
2 PM Thu 69 70 E 3 8645 7646 3146 Blue 11
3 PM Thu 67 67 SE 3 7680 6683 2183 Blue 8
4 PM Thu 64 64 SE 2 6704 5818 1318 Blue 5
5 PM Thu 59 59 S 1 5240 4500 0 Blue 0
6 PM Thu 53 53 W 0 3305 4500 0 Blue 0
7 PM Thu 48 48 NW 0 2874 4500 0 Blue 0
8 PM Thu 45 45 NW 0 2874 4500 0 Blue 0
9 PM Thu 42 42 W 1 2874 4500 0 Blue 0
10 PM Thu 41 41 W 2 2874 4500 0 Blue 0
11 PM Thu 39 39 W 3 2874 4500 0 Blue 0
12 Midnight Fri 38 38 W 3 2874 4500 0 Blue 0
1 AM Fri 36 36 W 3 2874 4500 0 Blue 0
2 AM Fri 33 33 W 3 2874 4500 0 Blue 0
3 AM Fri 31 31 W 2 2874 4500 0 Blue 0
4 AM Fri 31 31 NW 2 2874 4500 0 Blue 0
5 AM Fri 33 33 W 2 2874 4500 0 Blue 0
6 AM Fri 37 37 W 2 2874 4500 0 Blue 0
7 AM Fri 43 43 SW 2 2874 4500 0 Blue 0
8 AM Fri 49 49 SW 2 2874 4500 0 Blue 0
9 AM Fri 55 56 S 3 4290 4500 0 Blue 0
10 AM Fri 61 62 S 3 6124 5232 732 Blue 3
11 AM Fri 64 66 S 3 7352 6397 1897 Blue 7
12 Noon Fri 66 68 SE 3 8004 6994 2494 Blue 9
1 PM Fri 67 69 SE 5 8326 7321 2821 Blue 10
2 PM Fri 67 68 SE 5 8004 6994 2494 Blue 9
3 PM Fri 65 65 E 5 7021 6108 1608 Blue 6
4 PM Fri 63 63 E 5 6415 5526 1026 Blue 4
5 PM Fri 61 61 SE 5 5831 4928 428 Blue 2
6 PM Fri 58 58 SE 5 4933 4500 0 Blue 0
7 PM Fri 54 54 S 5 3636 4500 0 Blue 0
8 PM Fri 51 51 S 3 2874 4500 0 Blue 0
9 PM Fri 47 47 SW 3 2874 4500 0 Blue 0
10 PM Fri 44 44 SW 3 2874 4500 0 Blue 0
11 PM Fri 40 40 W 3 2874 4500 0 Blue 0
12 Midnight Sat 37 37 W 3 2874 4500 0 Blue 0
1 AM Sat 34 34 W 3 2874 4500 0 Blue 0
2 AM Sat 32 32 W 3 2874 4500 0 Blue 0
3 AM Sat 32 32 W 3 2874 4500 0 Blue 0
4 AM Sat 33 33 NW 3 2874 4500 0 Blue 0
5 AM Sat 36 36 W 3 2874 4500 0 Blue 0
6 AM Sat 40 40 W 3 2874 4500 0 Blue 0
7 AM Sat 45 45 W 3 2874 4500 0 Blue 0
8 AM Sat 50 50 SW 3 2874 4500 0 Blue 0
9 AM Sat 55 56 S 3 4290 4500 0 Blue 0
10 AM Sat 59 60 S 3 5536 4611 111 Blue 1
11 AM Sat 62 64 S 3 6704 5818 1318 Blue 5
12 Noon Sat 64 66 S 3 7352 6397 1897 Blue 7
1 PM Sat 65 67 SE 5 7680 6683 2183 Blue 8
2 PM Sat 65 66 SE 5 7352 6397 1897 Blue 7
3 PM Sat 64 64 E 5 6704 5818 1318 Blue 5
4 PM Sat 62 62 E 5 6124 5232 732 Blue 3
5 PM Sat 60 60 E 5 5536 4611 111 Blue 1
6 PM Sat 57 57 SE 5 4613 4500 0 Blue 0
7 PM Sat 54 54 S 5 3636 4500 0 Blue 0
8 PM Sat 50 50 S 5 2874 4500 0 Blue 0
9 PM Sat 46 46 SW 3 2874 4500 0 Blue 0
10 PM Sat 43 43 SW 3 2874 4500 0 Blue 0
11 PM Sat 39 39 SW 3 2874 4500 0 Blue 0
12 Midnight Sun 36 36 W 2 2874 4500 0 Blue 0
1 AM Sun 33 33 W 2 2874 4500 0 Blue 0
2 AM Sun 31 31 W 1 2874 4500 0 Blue 0
3 AM Sun 31 31 W 1 2874 4500 0 Blue 0
4 AM Sun 32 32 W 1 2874 4500 0 Blue 0
5 AM Sun 35 35 W 1 2874 4500 0 Blue 0
6 AM Sun 39 39 SW 2 2874 4500 0 Blue 0
7 AM Sun 44 44 S 2 2874 4500 0 Blue 0
8 AM Sun 49 49 S 3 2874 4500 0 Blue 0
9 AM Sun 54 55 SE 3 3965 4500 0 Blue 0
10 AM Sun 58 59 E 5 5240 4500 0 Blue 0
11 AM Sun 61 63 SE 5 6415 5526 1026 Blue 4
12 Noon Sun 63 65 SE 6 7021 6108 1608 Blue 6
1 PM Sun 64 65 SE 6 7021 6108 1608 Blue 6
2 PM Sun 64 65 SE 6 7021 6108 1608 Blue 6
3 PM Sun 63 63 SE 6 6415 5526 1026 Blue 4
4 PM Sun 61 61 SE 6 5831 4928 428 Blue 2
5 PM Sun 58 58 SE 6 4933 4500 0 Blue 0
6 PM Sun 55 55 SE 6 3965 4500 0 Blue 0
7 PM Sun 51 51 SE 6 2874 4500 0 Blue 0
8 PM Sun 48 48 SE 5 2874 4500 0 Blue 0
9 PM Sun 44 44 SE 5 2874 4500 0 Blue 0
10 PM Sun 40 40 SE 5 2874 4500 0 Blue 0
11 PM Sun 37 37 SE 5 2874 4500 0 Blue 0
12 Midnight Mon 35 35 E 5 2874 4500 0 Blue 0
1 AM Mon 33 33 E 3 2874 4500 0 Blue 0
2 AM Mon 32 32 E 3 2874 4500 0 Blue 0
3 AM Mon 32 32 NE 3 2874 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