Detailed Predictions for: Chalk Bluffs
Launch Lat, Long, Altitude (f): 37.416328, -118.442829, 4500
LZ Altitude (f): 4220
Sounding

Station:

 KVBG

Date/Time UTC:

 251216/1200

Temp/Wind data from:

NOAA Digital Forecast

Site Forecasts
Time
(Local)		 High
Temp
Puddle
Temp
Wind
 (mph)		 Wind
 Gust		 Thermal
Ceiling
(ft)		 Soaring
Ceiling
(ft)		 Above
Launch
(ft)		 Thermal
Type		 Thermal
Index
(F)
12 Midnight Tue 43 43 NW 6 10 3999 4500 0 Blue 0
1 AM Tue 43 43 NW 6 10 3999 4500 0 Blue 0
2 AM Tue 43 43 NW 6 9 3999 4500 0 Blue 0
3 AM Tue 41 41 NW 5 9 3999 4500 0 Blue 0
4 AM Tue 41 41 NW 5 8 3999 4500 0 Blue 0
5 AM Tue 40 40 NW 5 8 3999 4500 0 Blue 0
6 AM Tue 39 39 NW 5 8 3999 4500 0 Blue 0
7 AM Tue 41 41 NW 5 8 3999 4500 0 Blue 0
8 AM Tue 44 44 NW 4 6 3999 4500 0 Blue 0
9 AM Tue 52 52 NW 3 5 3999 4500 0 Blue 0
10 AM Tue 57 57 NNW 2 5 3999 4500 0 Blue 0
11 AM Tue 62 63 WNW 2 6 4308 4500 0 Blue 0
12 Noon Tue 65 66 W 3 8 6048 4500 0 Blue 3
1 PM Tue 66 67 S 3 8 6363 5051 551 Blue 4
2 PM Tue 68 69 S 3 8 6986 6031 1531 Blue 6
3 PM Tue 67 67 SSE 4 8 6363 5051 551 Blue 4
4 PM Tue 65 65 SSE 5 9 5737 4500 0 Blue 2
5 PM Tue 61 61 SSW 5 11 3999 4500 0 Blue 0
6 PM Tue 55 55 WNW 8 12 3999 4500 0 Blue 0
7 PM Tue 53 53 NW 9 13 3999 4500 0 Blue 0
8 PM Tue 52 52 NW 10 16 3999 4500 0 Blue 0
9 PM Tue 50 50 WNW 10 17 3999 4500 0 Blue 0
10 PM Tue 48 48 NW 10 17 3999 4500 0 Blue 0
11 PM Tue 47 47 NW 10 17 3999 4500 0 Blue 0
12 Midnight Wed 46 46 WNW 10 16 3999 4500 0 Blue 0
1 AM Wed 45 45 WNW 10 14 3999 4500 0 Blue 0
2 AM Wed 45 45 NW 10 13 3999 4500 0 Blue 0
3 AM Wed 44 44 WNW 10 13 3999 4500 0 Blue 0
4 AM Wed 42 42 WNW 10 12 3999 4500 0 Blue 0
5 AM Wed 42 42 WNW 10 12 3999 4500 0 Blue 0
6 AM Wed 42 42 WNW 10 12 3999 4500 0 Blue 0
7 AM Wed 41 41 W 10 12 3999 4500 0 Blue 0
8 AM Wed 46 46 W 10 12 3999 4500 0 Blue 0
9 AM Wed 54 54 WNW 9 12 3999 4500 0 Blue 0
10 AM Wed 61 62 WNW 9 13 3999 4500 0 Blue 0
11 AM Wed 65 67 WNW 9 14 6363 5051 551 Blue 4
12 Noon Wed 67 69 NW 10 16 6986 6031 1531 Blue 6
1 PM Wed 68 70 NW 10 17 7151 6344 1844 Blue 7
2 PM Wed 69 70 NW 10 17 7151 6344 1844 Blue 7
3 PM Wed 68 68 NW 10 16 6675 5724 1224 Blue 5
4 PM Wed 66 66 NW 10 14 6048 4500 0 Blue 3
5 PM Wed 61 61 NW 10 14 3999 4500 0 Blue 0
6 PM Wed 56 56 WNW 10 16 3999 4500 0 Blue 0
7 PM Wed 51 51 WNW 10 16 3999 4500 0 Blue 0
8 PM Wed 48 48 WNW 10 16 3999 4500 0 Blue 0
9 PM Wed 47 47 WNW 10 16 3999 4500 0 Blue 0
10 PM Wed 46 46 WNW 10 16 3999 4500 0 Blue 0
11 PM Wed 45 45 WNW 10 16 3999 4500 0 Blue 0
12 Midnight Thu 44 44 W 9 14 3999 4500 0 Blue 0
1 AM Thu 43 43 W 9 13 3999 4500 0 Blue 0
2 AM Thu 42 42 W 9 12 3999 4500 0 Blue 0
3 AM Thu 41 41 W 8 11 3999 4500 0 Blue 0
4 AM Thu 41 41 W 8 10 3999 4500 0 Blue 0
5 AM Thu 40 40 W 8 10 3999 4500 0 Blue 0
6 AM Thu 39 39 W 6 10 3999 4500 0 Blue 0
7 AM Thu 41 41 W 6 10 3999 4500 0 Blue 0
8 AM Thu 47 47 W 6 10 3999 4500 0 Blue 0
9 AM Thu 54 54 W 5 10 3999 4500 0 Blue 0
10 AM Thu 61 62 W 5 10 3999 4500 0 Blue 0
11 AM Thu 65 66 W 5 10 6048 4500 0 Blue 3
12 Noon Thu 68 69 W 5 11 6986 6031 1531 Blue 6
1 PM Thu 69 70 W 5 11 7151 6344 1844 Blue 7
2 PM Thu 69 69 W 5 11 6986 6031 1531 Blue 6
3 PM Thu 68 68 WSW 6 11 6675 5724 1224 Blue 5
4 PM Thu 66 66 WSW 8 12 6048 4500 0 Blue 3
5 PM Thu 62 62 WSW 9 14 3999 4500 0 Blue 0
6 PM Thu 57 57 WSW 10 17 3999 4500 0 Blue 0
7 PM Thu 52 52 WSW 11 18 3999 4500 0 Blue 0
8 PM Thu 50 50 WSW 12 18 3999 4500 0 Blue 0
9 PM Thu 48 48 WSW 12 18 3999 4500 0 Blue 0
10 PM Thu 47 47 WSW 12 18 3999 4500 0 Blue 0
11 PM Thu 46 46 WSW 12 18 3999 4500 0 Blue 0
12 Midnight Fri 44 44 WSW 12 18 3999 4500 0 Blue 0
1 AM Fri 43 43 WSW 12 18 3999 4500 0 Blue 0
2 AM Fri 42 42 WSW 12 17 3999 4500 0 Blue 0
3 AM Fri 41 41 WSW 11 16 3999 4500 0 Blue 0
4 AM Fri 40 40 WSW 11 14 3999 4500 0 Blue 0
5 AM Fri 39 39 WSW 11 14 3999 4500 0 Blue 0
6 AM Fri 40 40 WSW 11 14 3999 4500 0 Blue 0
7 AM Fri 42 42 WSW 11 14 3999 4500 0 Blue 0
8 AM Fri 47 47 WSW 11 14 3999 4500 0 Blue 0
9 AM Fri 54 54 WSW 10 16 3999 4500 0 Blue 0
10 AM Fri 60 61 WSW 10 17 3999 4500 0 Blue 0
11 AM Fri 64 65 WSW 11 19 5737 4500 0 Blue 2
12 Noon Fri 67 68 WSW 12 21 6675 5724 1224 Blue 5
1 PM Fri 68 69 WSW 13 23 6986 6031 1531 Blue 6
2 PM Fri 68 69 WSW 13 23 6986 6031 1531 Blue 6
3 PM Fri 67 67 WSW 13 21 6363 5051 551 Blue 4
4 PM Fri 65 65 WSW 13 20 5737 4500 0 Blue 2
5 PM Fri 61 61 WSW 13 21 3999 4500 0 Blue 0
6 PM Fri 56 56 W 14 24 3999 4500 0 Blue 0
7 PM Fri 52 52 W 14 25 3999 4500 0 Blue 0
8 PM Fri 50 50 W 14 25 3999 4500 0 Blue 0
9 PM Fri 49 49 W 13 23 3999 4500 0 Blue 0
10 PM Fri 48 48 W 13 21 3999 4500 0 Blue 0
11 PM Fri 47 47 W 13 20 3999 4500 0 Blue 0
12 Midnight Sat 47 47 W 12 19 3999 4500 0 Blue 0
1 AM Sat 46 46 W 12 18 3999 4500 0 Blue 0
2 AM Sat 45 45 W 11 17 3999 4500 0 Blue 0
3 AM Sat 44 44 W 11 14 3999 4500 0 Blue 0
4 AM Sat 43 43 W 10 13 3999 4500 0 Blue 0
5 AM Sat 41 41 W 10 13 3999 4500 0 Blue 0
6 AM Sat 40 40 W 10 13 3999 4500 0 Blue 0
7 AM Sat 41 41 W 10 13 3999 4500 0 Blue 0
8 AM Sat 46 46 W 9 12 3999 4500 0 Blue 0
9 AM Sat 52 52 W 8 12 3999 4500 0 Blue 0
10 AM Sat 58 59 WSW 8 12 3999 4500 0 Blue 0
11 AM Sat 62 63 WSW 9 14 4308 4500 0 Blue 0
12 Noon Sat 65 66 SSW 10 17 6048 4500 0 Blue 3
1 PM Sat 66 67 SSW 11 19 6363 5051 551 Blue 4
2 PM Sat 66 66 SSW 11 19 6048 4500 0 Blue 3
3 PM Sat 65 65 SW 10 19 5737 4500 0 Blue 2
4 PM Sat 63 63 SW 10 18 4308 4500 0 Blue 0
5 PM Sat 60 60 SW 10 18 3999 4500 0 Blue 0
6 PM Sat 56 56 WSW 11 18 3999 4500 0 Blue 0
7 PM Sat 52 52 WSW 11 18 3999 4500 0 Blue 0
8 PM Sat 50 50 WSW 11 18 3999 4500 0 Blue 0
9 PM Sat 49 49 WSW 10 17 3999 4500 0 Blue 0
10 PM Sat 48 48 WSW 10 17 3999 4500 0 Blue 0
11 PM Sat 47 47 WSW 10 16 3999 4500 0 Blue 0
12 Midnight Sun 47 47 WSW 10 16 3999 4500 0 Blue 0
1 AM Sun 46 46 WSW 10 14 3999 4500 0 Blue 0
2 AM Sun 45 45 WSW 10 13 3999 4500 0 Blue 0
3 AM Sun 44 44 WSW 9 12 3999 4500 0 Blue 0
4 AM Sun 43 43 WSW 9 11 3999 4500 0 Blue 0
5 AM Sun 42 42 WSW 9 11 3999 4500 0 Blue 0
6 AM Sun 41 41 SW 8 11 3999 4500 0 Blue 0
7 AM Sun 42 42 SW 8 11 3999 4500 0 Blue 0
8 AM Sun 46 46 SW 8 12 3999 4500 0 Blue 0
9 AM Sun 51 51 SSW 8 13 3999 4500 0 Blue 0
10 AM Sun 56 56 S 9 14 3999 4500 0 Blue 0
11 AM Sun 60 60 S 10 17 3999 4500 0 Blue 0
12 Noon Sun 62 63 S 11 19 4308 4500 0 Blue 0
1 PM Sun 64 64 S 12 21 5058 4500 0 Blue 1
2 PM Sun 65 65 S 12 21 5737 4500 0 Blue 2
3 PM Sun 64 64 S 12 20 5058 4500 0 Blue 1
4 PM Sun 62 62 S 12 20 3999 4500 0 Blue 0
5 PM Sun 59 59 S 12 21 3999 4500 0 Blue 0
6 PM Sun 55 55 SSW 12 23 3999 4500 0 Blue 0
7 PM Sun 51 51 SSW 12 23 3999 4500 0 Blue 0
8 PM Sun 49 49 SSW 12 21 3999 4500 0 Blue 0
9 PM Sun 48 48 SSW 11 20 3999 4500 0 Blue 0
10 PM Sun 47 47 SSW 11 19 3999 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 or WeatherAPI.com website.  Puddle temperatures can exceed this temperature. 

Puddle Temp: This estimate is based on the High Temp and the National Weather Service or WeatherAPI.com 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 or WeatherAPI.com website.

Wind Gust: This estimate is taken from the National Weather Service or WeatherAPI.com 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 [email protected]