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

Station:

KVBG

Date/Time:

26 MAR 2019

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)
5 AM Tue 41 41 NW 5 4380 4500 0 Blue 0
6 AM Tue 37 37 SW 9 4380 4500 0 Blue 0
7 AM Tue 38 38 SW 9 4380 4500 0 Blue 0
8 AM Tue 40 40 NW 9 4380 4500 0 Blue 0
9 AM Tue 47 47 S 8 4380 4500 0 Blue 0
10 AM Tue 53 54 SW 9 6892 5112 612 Blue 4
11 AM Tue 58 60 S 9 9607 8477 3977 White 10
12 Noon Tue 61 63 SE 9 10070 9648 5148 Blue 13
1 PM Tue 63 66 S 10 10756 10009 5509 Blue 16
2 PM Tue 67 70 SW 13 11754 11209 6709 White 20
3 PM Tue 67 69 SW 14 11544 10719 6219 White 19
4 PM Tue 67 68 SW 14 11334 10532 6032 White 18
5 PM Tue 67 67 SW 14 11123 10277 5777 White 17
6 PM Tue 65 65 SW 14 10582 9823 5323 Blue 15
7 PM Tue 61 61 SW 13 9758 8988 4488 Blue 11
8 PM Tue 56 56 SW 13 8013 6264 1764 Blue 6
9 PM Tue 53 53 W 13 6301 4815 315 Blue 3
10 PM Tue 50 50 SW 12 4819 4500 0 Blue 0
11 PM Tue 49 49 SW 12 4552 4500 0 Blue 0
12 Midnight Wed 47 47 SW 10 4380 4500 0 Blue 0
1 AM Wed 46 46 SW 10 4380 4500 0 Blue 0
2 AM Wed 43 43 SW 10 4380 4500 0 Blue 0
3 AM Wed 43 43 SW 10 4380 4500 0 Blue 0
4 AM Wed 42 42 SW 9 4380 4500 0 Blue 0
5 AM Wed 42 42 SW 10 4380 4500 0 Blue 0
6 AM Wed 41 41 SW 10 4380 4500 0 Blue 0
7 AM Wed 41 41 SW 10 4380 4500 0 Blue 0
8 AM Wed 43 43 SW 10 4380 4500 0 Blue 0
9 AM Wed 49 49 S 12 4552 4500 0 Blue 0
10 AM Wed 54 55 S 14 7462 5660 1160 Blue 5
11 AM Wed 59 62 SW 15 9837 9473 4973 Blue 12
12 Noon Wed 62 66 SW 16 10756 10009 5509 Blue 16
1 PM Wed 63 68 SW 17 11334 10532 6032 White 18
2 PM Wed 64 69 SW 18 11544 10719 6219 White 19
3 PM Wed 64 68 SW 18 11334 10532 6032 White 18
4 PM Wed 64 66 SW 18 10756 10009 5509 Blue 16
5 PM Wed 63 64 SW 18 10327 9742 5242 Blue 14
6 PM Wed 60 60 SW 17 9607 8477 3977 White 10
7 PM Wed 57 57 SW 17 8547 6846 2346 Blue 7
8 PM Wed 54 54 SW 16 6892 5112 612 Blue 4
9 PM Wed 52 52 SW 15 5685 4551 51 Blue 2
10 PM Wed 50 50 SW 15 4819 4500 0 Blue 0
11 PM Wed 48 48 SW 14 4380 4500 0 Blue 0
12 Midnight Thu 45 45 W 13 4380 4500 0 Blue 0
1 AM Thu 43 43 W 13 4380 4500 0 Blue 0
2 AM Thu 41 41 W 12 4380 4500 0 Blue 0
3 AM Thu 39 39 W 12 4380 4500 0 Blue 0
4 AM Thu 38 38 W 10 4380 4500 0 Blue 0
5 AM Thu 37 37 W 10 4380 4500 0 Blue 0
6 AM Thu 36 36 W 10 4380 4500 0 Blue 0
7 AM Thu 36 36 W 10 4380 4500 0 Blue 0
8 AM Thu 38 38 W 10 4380 4500 0 Blue 0
9 AM Thu 42 43 W 10 4380 4500 0 Blue 0
10 AM Thu 48 51 W 10 5120 4500 0 Blue 1
11 AM Thu 52 56 W 12 8013 6264 1764 Blue 6
12 Noon Thu 55 61 W 13 9758 8988 4488 Blue 11
1 PM Thu 57 63 W 14 10070 9648 5148 Blue 13
2 PM Thu 58 64 W 15 10327 9742 5242 Blue 14
3 PM Thu 59 63 W 16 10070 9648 5148 Blue 13
4 PM Thu 59 62 W 17 9837 9473 4973 Blue 12
5 PM Thu 58 59 W 17 9395 7950 3450 White 9
6 PM Thu 55 55 W 17 7462 5660 1160 Blue 5
7 PM Thu 52 52 W 16 5685 4551 51 Blue 2
8 PM Thu 48 48 W 15 4380 4500 0 Blue 0
9 PM Thu 45 45 W 14 4380 4500 0 Blue 0
10 PM Thu 43 43 W 14 4380 4500 0 Blue 0
11 PM Thu 41 41 W 13 4380 4500 0 Blue 0
12 Midnight Fri 39 39 W 12 4380 4500 0 Blue 0
1 AM Fri 37 37 NW 12 4380 4500 0 Blue 0
2 AM Fri 36 36 NW 10 4380 4500 0 Blue 0
3 AM Fri 34 34 NW 9 4380 4500 0 Blue 0
4 AM Fri 33 33 NW 7 4380 4500 0 Blue 0
5 AM Fri 33 33 NW 6 4380 4500 0 Blue 0
6 AM Fri 33 33 NW 6 4380 4500 0 Blue 0
7 AM Fri 34 34 NW 6 4380 4500 0 Blue 0
8 AM Fri 36 36 NW 6 4380 4500 0 Blue 0
9 AM Fri 40 41 NW 6 4380 4500 0 Blue 0
10 AM Fri 46 49 NW 6 4552 4500 0 Blue 0
11 AM Fri 51 55 NW 6 7462 5660 1160 Blue 5
12 Noon Fri 54 60 NW 6 9607 8477 3977 White 10
1 PM Fri 56 62 NW 6 9837 9473 4973 Blue 12
2 PM Fri 58 64 NW 7 10327 9742 5242 Blue 14
3 PM Fri 60 64 NW 8 10327 9742 5242 Blue 14
4 PM Fri 60 62 NW 9 9837 9473 4973 Blue 12
5 PM Fri 60 61 NW 10 9758 8988 4488 Blue 11
6 PM Fri 58 58 NW 10 9065 7407 2907 Blue 8
7 PM Fri 54 54 N 10 6892 5112 612 Blue 4
8 PM Fri 51 51 N 9 5120 4500 0 Blue 1
9 PM Fri 48 48 N 9 4380 4500 0 Blue 0
10 PM Fri 46 46 N 8 4380 4500 0 Blue 0
11 PM Fri 44 44 N 8 4380 4500 0 Blue 0
12 Midnight Sat 42 42 N 7 4380 4500 0 Blue 0
1 AM Sat 40 40 NW 7 4380 4500 0 Blue 0
2 AM Sat 38 38 NW 6 4380 4500 0 Blue 0
3 AM Sat 36 36 NW 5 4380 4500 0 Blue 0
4 AM Sat 35 35 NW 5 4380 4500 0 Blue 0
5 AM Sat 35 35 NW 5 4380 4500 0 Blue 0
6 AM Sat 35 35 NW 5 4380 4500 0 Blue 0
7 AM Sat 36 36 NW 6 4380 4500 0 Blue 0
8 AM Sat 38 38 NW 6 4380 4500 0 Blue 0
9 AM Sat 42 43 NW 6 4380 4500 0 Blue 0
10 AM Sat 47 50 N 7 4819 4500 0 Blue 0
11 AM Sat 52 56 N 7 8013 6264 1764 Blue 6
12 Noon Sat 55 60 N 7 9607 8477 3977 White 10
1 PM Sat 58 63 N 8 10070 9648 5148 Blue 13
2 PM Sat 60 64 N 8 10327 9742 5242 Blue 14
3 PM Sat 62 65 N 8 10582 9823 5323 Blue 15
4 PM Sat 62 64 N 9 10327 9742 5242 Blue 14
5 PM Sat 62 63 N 9 10070 9648 5148 Blue 13
6 PM Sat 60 60 N 9 9607 8477 3977 White 10
7 PM Sat 56 56 N 9 8013 6264 1764 Blue 6
8 PM Sat 53 53 N 8 6301 4815 315 Blue 3
9 PM Sat 50 50 N 7 4819 4500 0 Blue 0
10 PM Sat 48 48 W 7 4380 4500 0 Blue 0
11 PM Sat 46 46 W 6 4380 4500 0 Blue 0
12 Midnight Sun 44 44 W 6 4380 4500 0 Blue 0
1 AM Sun 42 42 W 5 4380 4500 0 Blue 0
2 AM Sun 40 40 W 5 4380 4500 0 Blue 0
3 AM Sun 39 39 W 5 4380 4500 0 Blue 0
4 AM Sun 38 38 W 3 4380 4500 0 Blue 0
5 AM Sun 38 38 W 3 4380 4500 0 Blue 0
6 AM Sun 38 38 W 3 4380 4500 0 Blue 0
7 AM Sun 39 39 W 3 4380 4500 0 Blue 0
8 AM Sun 41 41 W 3 4380 4500 0 Blue 0
9 AM Sun 46 47 W 3 4380 4500 0 Blue 0
10 AM Sun 52 54 N 5 6892 5112 612 Blue 4
11 AM Sun 57 61 N 5 9758 8988 4488 Blue 11
12 Noon Sun 60 64 NE 6 10327 9742 5242 Blue 14
1 PM Sun 63 67 SE 6 11123 10277 5777 White 17
2 PM Sun 64 68 S 7 11334 10532 6032 White 18
3 PM Sun 66 69 S 8 11544 10719 6219 White 19
4 PM Sun 66 68 S 8 11334 10532 6032 White 18
5 PM Sun 66 66 S 8 10756 10009 5509 Blue 16
6 PM Sun 64 64 S 8 10327 9742 5242 Blue 14
7 PM Sun 60 60 SW 7 9607 8477 3977 White 10
8 PM Sun 57 57 SW 7 8547 6846 2346 Blue 7
9 PM Sun 55 55 SW 7 7462 5660 1160 Blue 5
10 PM Sun 53 53 W 6 6301 4815 315 Blue 3
11 PM Sun 51 51 W 6 5120 4500 0 Blue 1
12 Midnight Mon 49 49 W 6 4552 4500 0 Blue 0
1 AM Mon 47 47 W 6 4380 4500 0 Blue 0
2 AM Mon 45 45 W 6 4380 4500 0 Blue 0
3 AM Mon 43 43 W 5 4380 4500 0 Blue 0
4 AM Mon 42 42 W 5 4380 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