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

Station:

KVBG

Date/Time:

N/A

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 6 N/A N/A N/A N/A N/A
5 AM Wed 31 31 NW 6 N/A N/A N/A N/A N/A
6 AM Wed 31 31 NW 6 N/A N/A N/A N/A N/A
7 AM Wed 29 29 NW 7 N/A N/A N/A N/A N/A
8 AM Wed 35 35 W 6 N/A N/A N/A N/A N/A
9 AM Wed 43 43 SW 6 N/A N/A N/A N/A N/A
10 AM Wed 50 51 SE 5 N/A N/A N/A N/A N/A
11 AM Wed 54 56 SE 5 N/A N/A N/A N/A N/A
12 Noon Wed 58 60 SE 5 N/A N/A N/A N/A N/A
1 PM Wed 60 61 SE 6 N/A N/A N/A N/A N/A
2 PM Wed 61 62 S 6 N/A N/A N/A N/A N/A
3 PM Wed 61 61 W 7 N/A N/A N/A N/A N/A
4 PM Wed 57 57 NW 8 N/A N/A N/A N/A N/A
5 PM Wed 50 50 NW 9 N/A N/A N/A N/A N/A
6 PM Wed 46 46 N 12 N/A N/A N/A N/A N/A
7 PM Wed 44 44 N 14 N/A N/A N/A N/A N/A
8 PM Wed 40 40 N 15 N/A N/A N/A N/A N/A
9 PM Wed 38 38 N 15 N/A N/A N/A N/A N/A
10 PM Wed 37 37 N 15 N/A N/A N/A N/A N/A
11 PM Wed 34 34 N 15 N/A N/A N/A N/A N/A
12 Midnight Thu 34 34 N 15 N/A N/A N/A N/A N/A
1 AM Thu 31 31 N 14 N/A N/A N/A N/A N/A
2 AM Thu 30 30 N 13 N/A N/A N/A N/A N/A
3 AM Thu 28 28 NW 12 N/A N/A N/A N/A N/A
4 AM Thu 27 27 NW 9 N/A N/A N/A N/A N/A
5 AM Thu 25 25 NW 8 N/A N/A N/A N/A N/A
6 AM Thu 24 24 N 8 N/A N/A N/A N/A N/A
7 AM Thu 23 23 N 8 N/A N/A N/A N/A N/A
8 AM Thu 29 29 N 8 N/A N/A N/A N/A N/A
9 AM Thu 35 35 N 9 N/A N/A N/A N/A N/A
10 AM Thu 39 40 N 9 N/A N/A N/A N/A N/A
11 AM Thu 43 45 N 8 N/A N/A N/A N/A N/A
12 Noon Thu 45 47 N 7 N/A N/A N/A N/A N/A
1 PM Thu 46 48 N 6 N/A N/A N/A N/A N/A
2 PM Thu 47 48 N 6 N/A N/A N/A N/A N/A
3 PM Thu 47 47 N 7 N/A N/A N/A N/A N/A
4 PM Thu 45 45 N 8 N/A N/A N/A N/A N/A
5 PM Thu 42 42 N 9 N/A N/A N/A N/A N/A
6 PM Thu 38 38 NW 10 N/A N/A N/A N/A N/A
7 PM Thu 35 35 NW 10 N/A N/A N/A N/A N/A
8 PM Thu 32 32 NW 10 N/A N/A N/A N/A N/A
9 PM Thu 30 30 NW 9 N/A N/A N/A N/A N/A
10 PM Thu 29 29 NW 8 N/A N/A N/A N/A N/A
11 PM Thu 27 27 NW 8 N/A N/A N/A N/A N/A
12 Midnight Fri 26 26 NW 8 N/A N/A N/A N/A N/A
1 AM Fri 25 25 NW 8 N/A N/A N/A N/A N/A
2 AM Fri 25 25 NW 8 N/A N/A N/A N/A N/A
3 AM Fri 25 25 NW 8 N/A N/A N/A N/A N/A
4 AM Fri 24 24 NW 8 N/A N/A N/A N/A N/A
5 AM Fri 22 22 NW 8 N/A N/A N/A N/A N/A
6 AM Fri 21 21 N 7 N/A N/A N/A N/A N/A
7 AM Fri 23 23 N 6 N/A N/A N/A N/A N/A
8 AM Fri 29 29 N 6 N/A N/A N/A N/A N/A
9 AM Fri 37 37 N 5 N/A N/A N/A N/A N/A
10 AM Fri 44 45 N 5 N/A N/A N/A N/A N/A
11 AM Fri 49 51 N 5 N/A N/A N/A N/A N/A
12 Noon Fri 52 54 N 5 N/A N/A N/A N/A N/A
1 PM Fri 54 56 N 6 N/A N/A N/A N/A N/A
2 PM Fri 55 56 NE 6 N/A N/A N/A N/A N/A
3 PM Fri 55 55 NE 6 N/A N/A N/A N/A N/A
4 PM Fri 53 53 E 6 N/A N/A N/A N/A N/A
5 PM Fri 50 50 NE 6 N/A N/A N/A N/A N/A
6 PM Fri 45 45 NE 5 N/A N/A N/A N/A N/A
7 PM Fri 40 40 N 5 N/A N/A N/A N/A N/A
8 PM Fri 37 37 N 5 N/A N/A N/A N/A N/A
9 PM Fri 36 36 NW 3 N/A N/A N/A N/A N/A
10 PM Fri 34 34 NW 3 N/A N/A N/A N/A N/A
11 PM Fri 32 32 NW 3 N/A N/A N/A N/A N/A
12 Midnight Sat 30 30 NW 5 N/A N/A N/A N/A N/A
1 AM Sat 29 29 NW 5 N/A N/A N/A N/A N/A
2 AM Sat 29 29 NW 5 N/A N/A N/A N/A N/A
3 AM Sat 29 29 NW 5 N/A N/A N/A N/A N/A
4 AM Sat 28 28 NW 5 N/A N/A N/A N/A N/A
5 AM Sat 26 26 NW 5 N/A N/A N/A N/A N/A
6 AM Sat 24 24 NW 3 N/A N/A N/A N/A N/A
7 AM Sat 26 26 N 3 N/A N/A N/A N/A N/A
8 AM Sat 32 32 N 2 N/A N/A N/A N/A N/A
9 AM Sat 41 41 N 2 N/A N/A N/A N/A N/A
10 AM Sat 50 51 N 2 N/A N/A N/A N/A N/A
11 AM Sat 55 57 N 2 N/A N/A N/A N/A N/A
12 Noon Sat 58 60 NE 3 N/A N/A N/A N/A N/A
1 PM Sat 59 61 NE 3 N/A N/A N/A N/A N/A
2 PM Sat 60 61 E 5 N/A N/A N/A N/A N/A
3 PM Sat 60 60 E 5 N/A N/A N/A N/A N/A
4 PM Sat 58 58 SE 6 N/A N/A N/A N/A N/A
5 PM Sat 54 54 E 6 N/A N/A N/A N/A N/A
6 PM Sat 48 48 E 5 N/A N/A N/A N/A N/A
7 PM Sat 44 44 NE 5 N/A N/A N/A N/A N/A
8 PM Sat 40 40 N 3 N/A N/A N/A N/A N/A
9 PM Sat 38 38 N 3 N/A N/A N/A N/A N/A
10 PM Sat 36 36 NW 3 N/A N/A N/A N/A N/A
11 PM Sat 35 35 NW 3 N/A N/A N/A N/A N/A
12 Midnight Sun 33 33 NW 3 N/A N/A N/A N/A N/A
1 AM Sun 32 32 NW 3 N/A N/A N/A N/A N/A
2 AM Sun 31 31 NW 5 N/A N/A N/A N/A N/A
3 AM Sun 30 30 NW 5 N/A N/A N/A N/A N/A
4 AM Sun 29 29 NW 5 N/A N/A N/A N/A N/A
5 AM Sun 27 27 NW 5 N/A N/A N/A N/A N/A
6 AM Sun 26 26 W 3 N/A N/A N/A N/A N/A
7 AM Sun 28 28 SW 3 N/A N/A N/A N/A N/A
8 AM Sun 34 34 SW 3 N/A N/A N/A N/A N/A
9 AM Sun 43 43 S 2 N/A N/A N/A N/A N/A
10 AM Sun 51 52 S 2 N/A N/A N/A N/A N/A
11 AM Sun 56 57 S 2 N/A N/A N/A N/A N/A
12 Noon Sun 59 61 S 3 N/A N/A N/A N/A N/A
1 PM Sun 60 61 S 3 N/A N/A N/A N/A N/A
2 PM Sun 61 62 S 5 N/A N/A N/A N/A N/A
3 PM Sun 61 61 SE 5 N/A N/A N/A N/A N/A
4 PM Sun 59 59 SE 6 N/A N/A N/A N/A N/A
5 PM Sun 55 55 S 5 N/A N/A N/A N/A N/A
6 PM Sun 49 49 S 5 N/A N/A N/A N/A N/A
7 PM Sun 44 44 S 5 N/A N/A N/A N/A N/A
8 PM Sun 41 41 S 5 N/A N/A N/A N/A N/A
9 PM Sun 38 38 S 3 N/A N/A N/A N/A N/A
10 PM Sun 37 37 S 3 N/A N/A N/A N/A N/A
11 PM Sun 35 35 S 3 N/A N/A N/A N/A N/A
12 Midnight Mon 34 34 S 5 N/A N/A N/A N/A N/A
1 AM Mon 33 33 S 5 N/A N/A N/A N/A N/A
2 AM Mon 33 33 S 5 N/A N/A N/A N/A N/A
3 AM Mon 33 33 S 5 N/A N/A N/A N/A N/A
4 AM Mon 32 32 S 6 N/A N/A N/A N/A N/A
5 AM Mon 30 30 S 5 N/A N/A N/A N/A N/A
6 AM Mon 29 29 S 5 N/A N/A N/A N/A N/A
7 AM Mon 31 31 S 5 N/A N/A N/A N/A N/A
8 AM Mon 36 36 S 3 N/A N/A N/A N/A N/A
9 AM Mon 43 43 S 3 N/A N/A N/A N/A N/A
10 AM Mon 51 52 S 3 N/A N/A N/A N/A N/A
11 AM Mon 56 57 S 3 N/A N/A N/A N/A N/A
12 Noon Mon 58 59 SE 5 N/A N/A N/A N/A N/A
1 PM Mon 60 61 SE 5 N/A N/A N/A N/A N/A
2 PM Mon 61 61 SE 6 N/A N/A N/A N/A N/A
3 PM Mon 61 61 SE 6 N/A N/A N/A N/A N/A
4 PM Mon 59 59 SE 7 N/A N/A N/A N/A N/A
5 PM Mon 55 55 S 7 N/A N/A N/A N/A N/A
6 PM Mon 50 50 S 6 N/A N/A N/A N/A N/A
7 PM Mon 45 45 S 6 N/A N/A N/A N/A N/A
8 PM Mon 42 42 SW 6 N/A N/A N/A N/A N/A
9 PM Mon 39 39 W 5 N/A N/A N/A N/A N/A
10 PM Mon 37 37 W 5 N/A N/A N/A N/A N/A
11 PM Mon 36 36 W 5 N/A N/A N/A N/A N/A
12 Midnight Tue 35 35 W 6 N/A N/A N/A N/A N/A
1 AM Tue 34 34 W 6 N/A N/A N/A N/A N/A
2 AM Tue 33 33 NW 7 N/A N/A N/A N/A N/A
3 AM Tue 33 33 NW 7 N/A N/A N/A N/A N/A

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