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

Station:

KVBG

Date/Time:

17 JAN 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 Wed 32 32 NW 5 4196 4500 0 Blue 0
5 AM Wed 32 32 NW 5 4196 4500 0 Blue 0
6 AM Wed 33 33 NW 3 4196 4500 0 Blue 0
7 AM Wed 32 32 NW 3 4196 4500 0 Blue 0
8 AM Wed 35 35 W 3 4196 4500 0 Blue 0
9 AM Wed 45 45 W 3 4196 4500 0 Blue 0
10 AM Wed 51 51 SW 3 4196 4500 0 Blue 0
11 AM Wed 55 56 SW 3 4196 4500 0 Blue 0
12 Noon Wed 59 60 S 3 4856 4500 0 Blue 0
1 PM Wed 62 63 SE 3 5828 4850 350 Blue 3
2 PM Wed 62 63 S 3 5828 4850 350 Blue 3
3 PM Wed 63 63 S 3 5828 4850 350 Blue 3
4 PM Wed 60 60 S 3 4856 4500 0 Blue 0
5 PM Wed 54 54 S 3 4196 4500 0 Blue 0
6 PM Wed 49 49 SW 3 4196 4500 0 Blue 0
7 PM Wed 46 46 W 3 4196 4500 0 Blue 0
8 PM Wed 44 44 W 3 4196 4500 0 Blue 0
9 PM Wed 42 42 W 3 4196 4500 0 Blue 0
10 PM Wed 41 41 W 3 4196 4500 0 Blue 0
11 PM Wed 39 39 W 3 4196 4500 0 Blue 0
12 Midnight Thu 39 39 N 3 4196 4500 0 Blue 0
1 AM Thu 38 38 N 3 4196 4500 0 Blue 0
2 AM Thu 37 37 NE 3 4196 4500 0 Blue 0
3 AM Thu 35 35 SE 3 4196 4500 0 Blue 0
4 AM Thu 34 34 S 3 4196 4500 0 Blue 0
5 AM Thu 34 34 S 3 4196 4500 0 Blue 0
6 AM Thu 35 35 S 3 4196 4500 0 Blue 0
7 AM Thu 34 34 SE 3 4196 4500 0 Blue 0
8 AM Thu 37 37 SE 3 4196 4500 0 Blue 0
9 AM Thu 47 47 SE 3 4196 4500 0 Blue 0
10 AM Thu 53 54 SE 5 4196 4500 0 Blue 0
11 AM Thu 57 58 SE 7 4196 4500 0 Blue 0
12 Noon Thu 61 62 SE 9 5542 4500 0 Blue 2
1 PM Thu 64 65 SE 12 6396 5532 1032 Blue 5
2 PM Thu 64 65 SE 12 6396 5532 1032 Blue 5
3 PM Thu 65 65 S 10 6396 5532 1032 Blue 5
4 PM Thu 62 62 S 9 5542 4500 0 Blue 2
5 PM Thu 56 56 S 7 4196 4500 0 Blue 0
6 PM Thu 51 51 SE 5 4196 4500 0 Blue 0
7 PM Thu 48 48 SE 3 4196 4500 0 Blue 0
8 PM Thu 46 46 SE 3 4196 4500 0 Blue 0
9 PM Thu 44 44 SE 3 4196 4500 0 Blue 0
10 PM Thu 43 43 SE 5 4196 4500 0 Blue 0
11 PM Thu 41 41 SE 5 4196 4500 0 Blue 0
12 Midnight Fri 41 41 SE 5 4196 4500 0 Blue 0
1 AM Fri 40 40 SE 5 4196 4500 0 Blue 0
2 AM Fri 39 39 SE 5 4196 4500 0 Blue 0
3 AM Fri 37 37 S 5 4196 4500 0 Blue 0
4 AM Fri 36 36 SW 5 4196 4500 0 Blue 0
5 AM Fri 36 36 SW 5 4196 4500 0 Blue 0
6 AM Fri 37 37 W 5 4196 4500 0 Blue 0
7 AM Fri 36 36 W 5 4196 4500 0 Blue 0
8 AM Fri 38 38 W 5 4196 4500 0 Blue 0
9 AM Fri 44 44 W 6 4196 4500 0 Blue 0
10 AM Fri 47 47 W 7 4196 4500 0 Blue 0
11 AM Fri 50 51 W 8 4196 4500 0 Blue 0
12 Noon Fri 52 53 W 9 4196 4500 0 Blue 0
1 PM Fri 53 54 W 10 4196 4500 0 Blue 0
2 PM Fri 54 54 W 10 4196 4500 0 Blue 0
3 PM Fri 54 54 W 10 4196 4500 0 Blue 0
4 PM Fri 51 51 NW 10 4196 4500 0 Blue 0
5 PM Fri 45 45 NW 10 4196 4500 0 Blue 0
6 PM Fri 40 40 NW 12 4196 4500 0 Blue 0
7 PM Fri 37 37 NW 12 4196 4500 0 Blue 0
8 PM Fri 35 35 NW 10 4196 4500 0 Blue 0
9 PM Fri 33 33 NW 10 4196 4500 0 Blue 0
10 PM Fri 33 33 NW 9 4196 4500 0 Blue 0
11 PM Fri 31 31 NW 10 4196 4500 0 Blue 0
12 Midnight Sat 31 31 NW 12 4196 4500 0 Blue 0
1 AM Sat 30 30 NW 12 4196 4500 0 Blue 0
2 AM Sat 29 29 NW 10 4196 4500 0 Blue 0
3 AM Sat 27 27 NW 9 4196 4500 0 Blue 0
4 AM Sat 26 26 NW 8 4196 4500 0 Blue 0
5 AM Sat 26 26 NW 8 4196 4500 0 Blue 0
6 AM Sat 27 27 NW 8 4196 4500 0 Blue 0
7 AM Sat 26 26 NW 8 4196 4500 0 Blue 0
8 AM Sat 28 28 NW 8 4196 4500 0 Blue 0
9 AM Sat 35 35 N 9 4196 4500 0 Blue 0
10 AM Sat 39 40 N 9 4196 4500 0 Blue 0
11 AM Sat 42 43 N 9 4196 4500 0 Blue 0
12 Noon Sat 44 46 N 9 4196 4500 0 Blue 0
1 PM Sat 46 47 N 9 4196 4500 0 Blue 0
2 PM Sat 46 47 NW 9 4196 4500 0 Blue 0
3 PM Sat 47 47 NW 9 4196 4500 0 Blue 0
4 PM Sat 44 44 NW 9 4196 4500 0 Blue 0
5 PM Sat 39 39 NW 8 4196 4500 0 Blue 0
6 PM Sat 35 35 NW 8 4196 4500 0 Blue 0
7 PM Sat 33 33 NW 7 4196 4500 0 Blue 0
8 PM Sat 31 31 W 6 4196 4500 0 Blue 0
9 PM Sat 29 29 W 6 4196 4500 0 Blue 0
10 PM Sat 29 29 W 5 4196 4500 0 Blue 0
11 PM Sat 28 28 W 5 4196 4500 0 Blue 0
12 Midnight Sun 27 27 SW 3 4196 4500 0 Blue 0
1 AM Sun 26 26 SW 3 4196 4500 0 Blue 0
2 AM Sun 25 25 S 3 4196 4500 0 Blue 0
3 AM Sun 24 24 S 3 4196 4500 0 Blue 0
4 AM Sun 23 23 S 5 4196 4500 0 Blue 0
5 AM Sun 23 23 S 6 4196 4500 0 Blue 0
6 AM Sun 24 24 S 8 4196 4500 0 Blue 0
7 AM Sun 23 23 SE 9 4196 4500 0 Blue 0
8 AM Sun 26 26 SE 12 4196 4500 0 Blue 0
9 AM Sun 35 35 SE 13 4196 4500 0 Blue 0
10 AM Sun 40 40 SE 14 4196 4500 0 Blue 0
11 AM Sun 43 44 SE 14 4196 4500 0 Blue 0
12 Noon Sun 46 47 SE 14 4196 4500 0 Blue 0
1 PM Sun 49 50 SE 13 4196 4500 0 Blue 0
2 PM Sun 49 49 S 12 4196 4500 0 Blue 0
3 PM Sun 50 50 S 12 4196 4500 0 Blue 0
4 PM Sun 47 47 S 10 4196 4500 0 Blue 0
5 PM Sun 43 43 S 10 4196 4500 0 Blue 0
6 PM Sun 39 39 S 10 4196 4500 0 Blue 0
7 PM Sun 36 36 S 10 4196 4500 0 Blue 0
8 PM Sun 35 35 S 9 4196 4500 0 Blue 0
9 PM Sun 33 33 SW 9 4196 4500 0 Blue 0
10 PM Sun 32 32 SW 9 4196 4500 0 Blue 0
11 PM Sun 31 31 SW 8 4196 4500 0 Blue 0
12 Midnight Mon 31 31 S 8 4196 4500 0 Blue 0
1 AM Mon 30 30 S 7 4196 4500 0 Blue 0
2 AM Mon 29 29 S 6 4196 4500 0 Blue 0
3 AM Mon 28 28 S 6 4196 4500 0 Blue 0
4 AM Mon 27 27 S 6 4196 4500 0 Blue 0
5 AM Mon 27 27 S 7 4196 4500 0 Blue 0
6 AM Mon 28 28 S 8 4196 4500 0 Blue 0
7 AM Mon 27 27 SE 9 4196 4500 0 Blue 0
8 AM Mon 30 30 SE 10 4196 4500 0 Blue 0
9 AM Mon 39 39 SE 12 4196 4500 0 Blue 0
10 AM Mon 44 44 SE 13 4196 4500 0 Blue 0
11 AM Mon 47 47 SE 13 4196 4500 0 Blue 0
12 Noon Mon 50 51 SE 13 4196 4500 0 Blue 0
1 PM Mon 53 54 S 12 4196 4500 0 Blue 0
2 PM Mon 53 53 S 10 4196 4500 0 Blue 0
3 PM Mon 54 54 S 10 4196 4500 0 Blue 0
4 PM Mon 51 51 S 9 4196 4500 0 Blue 0
5 PM Mon 46 46 SW 9 4196 4500 0 Blue 0
6 PM Mon 41 41 SW 8 4196 4500 0 Blue 0
7 PM Mon 38 38 W 8 4196 4500 0 Blue 0
8 PM Mon 36 36 W 8 4196 4500 0 Blue 0
9 PM Mon 34 34 NW 8 4196 4500 0 Blue 0
10 PM Mon 33 33 NW 8 4196 4500 0 Blue 0
11 PM Mon 32 32 NW 8 4196 4500 0 Blue 0
12 Midnight Tue 32 32 NW 8 4196 4500 0 Blue 0
1 AM Tue 31 31 N 8 4196 4500 0 Blue 0
2 AM Tue 30 30 N 8 4196 4500 0 Blue 0
3 AM Tue 28 28 N 8 4196 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