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

Station:

KVBG

Date/Time:

23 JUN 2021

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 Wed 64 64 WSW 4 8 4475 4500 0 Blue 0
1 AM Wed 61 61 W 3 7 4475 4500 0 Blue 0
2 AM Wed 58 58 W 3 6 4475 4500 0 Blue 0
3 AM Wed 57 57 W 3 6 4475 4500 0 Blue 0
4 AM Wed 57 57 W 3 6 4475 4500 0 Blue 0
5 AM Wed 56 56 WNW 3 6 4475 4500 0 Blue 0
6 AM Wed 59 59 WSW 2 4 4475 4500 0 Blue 0
7 AM Wed 62 62 S 1 3 4475 4500 0 Blue 0
8 AM Wed 64 65 SE 0 1 4475 4500 0 Blue 0
9 AM Wed 67 70 SE 2 2 5869 5123 623 Blue 3
10 AM Wed 70 75 SE 3 4 8271 7257 2757 Blue 8
11 AM Wed 72 79 SE 5 5 9750 8444 3944 Blue 12
12 Noon Wed 74 81 SSE 7 8 10379 9263 4763 Blue 14
1 PM Wed 75 81 SSE 9 10 10379 9263 4763 Blue 14
2 PM Wed 76 80 SSE 11 13 10077 8641 4141 Blue 13
3 PM Wed 76 80 S 10 11 10077 8641 4141 Blue 13
4 PM Wed 76 78 S 9 10 9364 8248 3748 Blue 11
5 PM Wed 76 77 S 8 9 8689 8050 3550 Blue 10
6 PM Wed 74 75 SSW 6 8 8271 7257 2757 Blue 8
7 PM Wed 72 72 SSW 5 6 7298 5614 1114 Blue 5
8 PM Wed 70 70 SSW 3 5 5869 5123 623 Blue 3
9 PM Wed 67 67 SW 4 6 5128 4500 0 Blue 0
10 PM Wed 64 64 WSW 4 8 4475 4500 0 Blue 0
11 PM Wed 61 61 WSW 5 9 4475 4500 0 Blue 0
12 Midnight Thu 60 60 W 4 8 4475 4500 0 Blue 0
1 AM Thu 59 59 WNW 4 8 4475 4500 0 Blue 0
2 AM Thu 58 58 NW 3 7 4475 4500 0 Blue 0
3 AM Thu 56 56 NW 2 5 4475 4500 0 Blue 0
4 AM Thu 55 55 NNW 2 4 4475 4500 0 Blue 0
5 AM Thu 54 54 NNW 1 2 4475 4500 0 Blue 0
6 AM Thu 57 57 W 1 2 4475 4500 0 Blue 0
7 AM Thu 60 60 SSW 1 1 4475 4500 0 Blue 0
8 AM Thu 63 64 SE 1 1 4475 4500 0 Blue 0
9 AM Thu 65 68 SE 1 2 5376 4500 0 Blue 1
10 AM Thu 67 72 SE 2 2 7298 5614 1114 Blue 5
11 AM Thu 70 77 SE 2 3 8689 8050 3550 Blue 10
12 Noon Thu 72 80 SE 3 4 10077 8641 4141 Blue 13
1 PM Thu 73 82 SE 4 5 10921 9695 5195 Blue 15
2 PM Thu 75 83 SE 5 6 11565 10019 5519 Blue 16
3 PM Thu 75 81 SSE 6 7 10379 9263 4763 Blue 14
4 PM Thu 75 78 SSW 6 8 9364 8248 3748 Blue 11
5 PM Thu 75 76 SW 7 8 8469 7711 3211 Blue 9
6 PM Thu 73 74 WSW 6 8 8073 6733 2233 Blue 7
7 PM Thu 72 72 WSW 5 8 7298 5614 1114 Blue 5
8 PM Thu 70 70 WSW 4 7 5869 5123 623 Blue 3
9 PM Thu 67 67 W 4 7 5128 4500 0 Blue 0
10 PM Thu 65 65 W 4 6 4475 4500 0 Blue 0
11 PM Thu 63 63 W 3 6 4475 4500 0 Blue 0
12 Midnight Fri 62 62 WNW 3 6 4475 4500 0 Blue 0
1 AM Fri 60 60 NW 3 6 4475 4500 0 Blue 0
2 AM Fri 59 59 NW 2 6 4475 4500 0 Blue 0
3 AM Fri 58 58 NW 2 5 4475 4500 0 Blue 0
4 AM Fri 57 57 NW 2 5 4475 4500 0 Blue 0
5 AM Fri 57 57 NW 2 5 4475 4500 0 Blue 0
6 AM Fri 59 59 SSW 2 4 4475 4500 0 Blue 0
7 AM Fri 62 62 ESE 2 3 4475 4500 0 Blue 0
8 AM Fri 64 65 N 2 2 4475 4500 0 Blue 0
9 AM Fri 67 70 NE 2 3 5869 5123 623 Blue 3
10 AM Fri 69 74 E 2 3 8073 6733 2233 Blue 7
11 AM Fri 72 79 SE 2 3 9750 8444 3944 Blue 12
12 Noon Fri 74 82 ESE 4 4 10921 9695 5195 Blue 15
1 PM Fri 76 84 ESE 5 6 12179 10329 5829 Blue 17
2 PM Fri 77 85 ESE 7 8 12768 10786 6286 Blue 18
3 PM Fri 78 84 ESE 7 8 12179 10329 5829 Blue 17
4 PM Fri 78 82 ESE 7 8 10921 9695 5195 Blue 15
5 PM Fri 78 81 ESE 7 8 10379 9263 4763 Blue 14
6 PM Fri 76 77 ESE 7 9 8689 8050 3550 Blue 10
7 PM Fri 74 74 ESE 6 10 8073 6733 2233 Blue 7
8 PM Fri 72 72 ESE 6 10 7298 5614 1114 Blue 5
9 PM Fri 70 70 SE 4 8 5869 5123 623 Blue 3
10 PM Fri 68 68 SE 3 6 5376 4500 0 Blue 1
11 PM Fri 65 65 SSE 1 3 4475 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]