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

Station:

KVBG

Date/Time:

19 NOV 2017

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 Sun 24 24 NW 5 3885 4500 0 Blue 0
5 AM Sun 23 23 NW 5 3885 4500 0 Blue 0
6 AM Sun 23 23 NW 5 3885 4500 0 Blue 0
7 AM Sun 23 23 NW 5 3885 4500 0 Blue 0
8 AM Sun 36 36 W 5 3885 4500 0 Blue 0
9 AM Sun 47 48 SW 3 3885 4500 0 Blue 0
10 AM Sun 52 53 SW 3 3885 4500 0 Blue 0
11 AM Sun 57 59 S 3 5369 4500 0 Blue 2
12 Noon Sun 61 63 S 3 5785 5422 922 Blue 6
1 PM Sun 63 64 SE 3 6061 5476 976 Blue 7
2 PM Sun 65 66 SE 3 6608 5773 1273 Blue 9
3 PM Sun 65 65 SE 3 6335 5593 1093 Blue 8
4 PM Sun 61 61 SE 3 5478 5313 813 Blue 4
5 PM Sun 55 55 S 3 3885 4500 0 Blue 0
6 PM Sun 51 51 W 5 3885 4500 0 Blue 0
7 PM Sun 46 46 W 5 3885 4500 0 Blue 0
8 PM Sun 43 43 W 5 3885 4500 0 Blue 0
9 PM Sun 41 41 NW 3 3885 4500 0 Blue 0
10 PM Sun 39 39 NW 3 3885 4500 0 Blue 0
11 PM Sun 37 37 NW 3 3885 4500 0 Blue 0
12 Midnight Mon 36 36 NW 3 3885 4500 0 Blue 0
1 AM Mon 35 35 NW 3 3885 4500 0 Blue 0
2 AM Mon 34 34 NW 3 3885 4500 0 Blue 0
3 AM Mon 33 33 NW 3 3885 4500 0 Blue 0
4 AM Mon 32 32 N 3 3885 4500 0 Blue 0
5 AM Mon 31 31 NW 3 3885 4500 0 Blue 0
6 AM Mon 31 31 NW 3 3885 4500 0 Blue 0
7 AM Mon 31 31 NW 3 3885 4500 0 Blue 0
8 AM Mon 43 43 NW 3 3885 4500 0 Blue 0
9 AM Mon 53 53 NW 3 3885 4500 0 Blue 0
10 AM Mon 58 59 NW 3 5369 4500 0 Blue 2
11 AM Mon 63 64 N 3 6061 5476 976 Blue 7
12 Noon Mon 66 67 N 3 6879 6046 1546 Blue 9
1 PM Mon 68 69 N 3 8019 6589 2089 Blue 11
2 PM Mon 70 70 N 3 8710 6858 2358 Blue 12
3 PM Mon 70 70 N 3 8710 6858 2358 Blue 12
4 PM Mon 66 66 N 3 6608 5773 1273 Blue 9
5 PM Mon 59 59 N 3 5369 4500 0 Blue 2
6 PM Mon 55 55 W 3 3885 4500 0 Blue 0
7 PM Mon 50 50 W 3 3885 4500 0 Blue 0
8 PM Mon 47 47 W 3 3885 4500 0 Blue 0
9 PM Mon 45 45 W 3 3885 4500 0 Blue 0
10 PM Mon 42 42 W 3 3885 4500 0 Blue 0
11 PM Mon 41 41 W 3 3885 4500 0 Blue 0
12 Midnight Tue 39 39 W 3 3885 4500 0 Blue 0
1 AM Tue 38 38 W 3 3885 4500 0 Blue 0
2 AM Tue 37 37 W 3 3885 4500 0 Blue 0
3 AM Tue 36 36 NW 3 3885 4500 0 Blue 0
4 AM Tue 35 35 NW 3 3885 4500 0 Blue 0
5 AM Tue 34 34 NW 3 3885 4500 0 Blue 0
6 AM Tue 34 34 N 3 3885 4500 0 Blue 0
7 AM Tue 34 34 N 3 3885 4500 0 Blue 0
8 AM Tue 46 46 N 3 3885 4500 0 Blue 0
9 AM Tue 56 56 E 3 4337 4500 0 Blue 0
10 AM Tue 61 62 E 3 5598 5368 868 Blue 5
11 AM Tue 66 67 E 3 6879 6046 1546 Blue 9
12 Noon Tue 69 70 SE 3 8710 6858 2358 Blue 12
1 PM Tue 71 72 SE 3 9994 7938 3438 Blue 14
2 PM Tue 73 74 SE 3 11079 9265 4765 Blue 16
3 PM Tue 73 73 SE 5 10679 8618 4118 Blue 15
4 PM Tue 69 69 SE 5 8019 6589 2089 Blue 11
5 PM Tue 62 62 SE 5 5598 5368 868 Blue 5
6 PM Tue 57 57 S 3 4798 4500 0 Blue 0
7 PM Tue 52 52 S 3 3885 4500 0 Blue 0
8 PM Tue 50 50 S 3 3885 4500 0 Blue 0
9 PM Tue 47 47 S 3 3885 4500 0 Blue 0
10 PM Tue 44 44 S 3 3885 4500 0 Blue 0
11 PM Tue 43 43 S 3 3885 4500 0 Blue 0
12 Midnight Wed 41 41 S 3 3885 4500 0 Blue 0
1 AM Wed 40 40 S 3 3885 4500 0 Blue 0
2 AM Wed 39 39 S 3 3885 4500 0 Blue 0
3 AM Wed 38 38 SW 3 3885 4500 0 Blue 0
4 AM Wed 37 37 SW 3 3885 4500 0 Blue 0
5 AM Wed 36 36 SW 3 3885 4500 0 Blue 0
6 AM Wed 36 36 S 3 3885 4500 0 Blue 0
7 AM Wed 36 36 S 3 3885 4500 0 Blue 0
8 AM Wed 49 49 S 3 3885 4500 0 Blue 0
9 AM Wed 59 59 SE 3 5369 4500 0 Blue 2
10 AM Wed 64 65 SE 3 6335 5593 1093 Blue 8
11 AM Wed 68 70 SE 3 8710 6858 2358 Blue 12
12 Noon Wed 72 74 SE 5 11079 9265 4765 Blue 16
1 PM Wed 74 75 SE 6 11335 9884 5384 Blue 17
2 PM Wed 76 77 SE 6 11842 11023 6523 Blue 19
3 PM Wed 76 76 SE 7 11589 10529 6029 Blue 18
4 PM Wed 72 72 SE 7 9994 7938 3438 Blue 14
5 PM Wed 64 64 SE 7 6061 5476 976 Blue 7
6 PM Wed 59 59 SE 6 5369 4500 0 Blue 2
7 PM Wed 53 53 SE 6 3885 4500 0 Blue 0
8 PM Wed 51 51 SE 5 3885 4500 0 Blue 0
9 PM Wed 48 48 S 3 3885 4500 0 Blue 0
10 PM Wed 45 45 S 3 3885 4500 0 Blue 0
11 PM Wed 44 44 SE 3 3885 4500 0 Blue 0
12 Midnight Thu 42 42 SE 3 3885 4500 0 Blue 0
1 AM Thu 40 40 SE 3 3885 4500 0 Blue 0
2 AM Thu 39 39 E 3 3885 4500 0 Blue 0
3 AM Thu 39 39 E 3 3885 4500 0 Blue 0
4 AM Thu 37 37 E 3 3885 4500 0 Blue 0
5 AM Thu 37 37 E 3 3885 4500 0 Blue 0
6 AM Thu 36 36 E 3 3885 4500 0 Blue 0
7 AM Thu 36 36 E 3 3885 4500 0 Blue 0
8 AM Thu 49 49 E 3 3885 4500 0 Blue 0
9 AM Thu 59 59 E 3 5369 4500 0 Blue 2
10 AM Thu 65 66 E 3 6608 5773 1273 Blue 9
11 AM Thu 69 70 SE 3 8710 6858 2358 Blue 12
12 Noon Thu 73 74 SE 3 11079 9265 4765 Blue 16
1 PM Thu 75 76 SE 3 11589 10529 6029 Blue 18
2 PM Thu 77 78 S 3 12359 11277 6777 Blue 20
3 PM Thu 77 77 S 3 11842 11023 6523 Blue 19
4 PM Thu 73 73 S 3 10679 8618 4118 Blue 15
5 PM Thu 65 65 SW 3 6335 5593 1093 Blue 8
6 PM Thu 60 60 SW 3 5424 4792 292 Blue 3
7 PM Thu 54 54 W 3 3885 4500 0 Blue 0
8 PM Thu 52 52 NW 3 3885 4500 0 Blue 0
9 PM Thu 49 49 NW 3 3885 4500 0 Blue 0
10 PM Thu 46 46 N 3 3885 4500 0 Blue 0
11 PM Thu 45 45 N 3 3885 4500 0 Blue 0
12 Midnight Fri 43 43 N 3 3885 4500 0 Blue 0
1 AM Fri 41 41 N 3 3885 4500 0 Blue 0
2 AM Fri 40 40 N 3 3885 4500 0 Blue 0
3 AM Fri 40 40 NE 3 3885 4500 0 Blue 0
4 AM Fri 38 38 NE 3 3885 4500 0 Blue 0
5 AM Fri 38 38 N 3 3885 4500 0 Blue 0
6 AM Fri 37 37 N 3 3885 4500 0 Blue 0
7 AM Fri 37 37 NW 3 3885 4500 0 Blue 0
8 AM Fri 49 49 W 3 3885 4500 0 Blue 0
9 AM Fri 58 58 SW 3 5315 4500 0 Blue 1
10 AM Fri 63 64 SW 3 6061 5476 976 Blue 7
11 AM Fri 67 68 SW 3 7288 6319 1819 Blue 10
12 Noon Fri 70 71 SW 3 9367 7220 2720 Blue 13
1 PM Fri 73 74 S 3 11079 9265 4765 Blue 16
2 PM Fri 74 75 S 3 11335 9884 5384 Blue 17
3 PM Fri 74 74 S 3 11079 9265 4765 Blue 16
4 PM Fri 70 70 S 3 8710 6858 2358 Blue 12
5 PM Fri 63 63 S 3 5785 5422 922 Blue 6
6 PM Fri 58 58 SE 3 5315 4500 0 Blue 1
7 PM Fri 53 53 E 3 3885 4500 0 Blue 0
8 PM Fri 50 50 E 3 3885 4500 0 Blue 0
9 PM Fri 47 47 NE 3 3885 4500 0 Blue 0
10 PM Fri 45 45 NE 3 3885 4500 0 Blue 0
11 PM Fri 43 43 E 3 3885 4500 0 Blue 0
12 Midnight Sat 42 42 E 3 3885 4500 0 Blue 0
1 AM Sat 40 40 SE 3 3885 4500 0 Blue 0
2 AM Sat 39 39 SE 3 3885 4500 0 Blue 0
3 AM Sat 38 38 S 3 3885 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