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