Detailed Predictions for: Lake McClure
Launch Altitude (f): 2000
LZ Altitude (f): 500
Sounding

Station:

KOAK

Date/Time:

26 APR 2018

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 Thu 56 56 NW 3 2389 2356 356 Blue 10
6 AM Thu 56 56 NW 3 2389 2356 356 Blue 10
7 AM Thu 56 56 NW 3 2389 2356 356 Blue 10
8 AM Thu 64 65 SW 2 2518 2454 454 Blue 19
9 AM Thu 70 72 SW 2 3012 2743 743 Blue 26
10 AM Thu 72 76 SW 2 4134 3095 1095 Blue 30
11 AM Thu 75 79 W 5 5112 4094 2094 Blue 33
12 Noon Thu 77 82 W 5 5711 5086 3086 Blue 36
1 PM Thu 78 84 W 5 6659 5484 3484 Blue 38
2 PM Thu 79 84 W 8 6659 5484 3484 Blue 38
3 PM Thu 80 84 W 8 6659 5484 3484 Blue 38
4 PM Thu 81 84 W 8 6659 5484 3484 Blue 38
5 PM Thu 80 81 NW 9 5511 4888 2888 Blue 35
6 PM Thu 79 79 NW 9 5112 4094 2094 Blue 33
7 PM Thu 74 74 NW 9 3278 2919 919 Blue 28
8 PM Thu 67 67 NW 9 2581 2493 493 Blue 21
9 PM Thu 63 63 NW 9 2471 2432 432 Blue 17
10 PM Thu 62 62 NW 9 2455 2421 421 Blue 16
11 PM Thu 59 59 NW 12 2422 2389 389 Blue 13
12 Midnight Fri 57 57 NW 12 2400 2367 367 Blue 11
1 AM Fri 54 54 NW 12 2367 2334 334 Blue 8
2 AM Fri 53 53 NW 12 2356 2323 323 Blue 7
3 AM Fri 53 53 NW 12 2356 2323 323 Blue 7
4 AM Fri 54 54 NW 12 2367 2334 334 Blue 8
5 AM Fri 53 53 NW 9 2356 2323 323 Blue 7
6 AM Fri 52 52 NW 9 2345 2299 299 Blue 6
7 AM Fri 52 52 NW 9 2345 2299 299 Blue 6
8 AM Fri 58 59 NW 9 2422 2389 389 Blue 13
9 AM Fri 63 65 NW 9 2518 2454 454 Blue 19
10 AM Fri 65 68 NW 9 2659 2517 517 Blue 22
11 AM Fri 67 72 W 9 3012 2743 743 Blue 26
12 Noon Fri 69 75 W 9 3709 3007 1007 Blue 29
1 PM Fri 69 76 W 9 4134 3095 1095 Blue 30
2 PM Fri 70 76 W 9 4134 3095 1095 Blue 30
3 PM Fri 72 77 W 9 4551 3248 1248 Blue 31
4 PM Fri 72 75 W 9 3709 3007 1007 Blue 29
5 PM Fri 72 74 NW 10 3278 2919 919 Blue 28
6 PM Fri 70 70 NW 10 2836 2579 579 Blue 24
7 PM Fri 66 66 NW 10 2541 2470 470 Blue 20
8 PM Fri 60 60 NW 10 2433 2399 399 Blue 14
9 PM Fri 56 56 NW 10 2389 2356 356 Blue 10
10 PM Fri 55 55 NW 10 2378 2345 345 Blue 9
11 PM Fri 53 53 NW 9 2356 2323 323 Blue 7
12 Midnight Sat 51 51 NW 9 2334 2255 255 Blue 5
1 AM Sat 49 49 NW 9 2301 2000 0 Blue 3
2 AM Sat 48 48 NW 9 2257 2000 0 Blue 2
3 AM Sat 48 48 NW 9 2257 2000 0 Blue 2
4 AM Sat 49 49 NW 9 2301 2000 0 Blue 3
5 AM Sat 48 48 NW 10 2257 2000 0 Blue 2
6 AM Sat 47 47 NW 10 2046 2000 0 White 1
7 AM Sat 47 47 NW 10 2046 2000 0 White 1
8 AM Sat 53 53 NW 10 2356 2323 323 Blue 7
9 AM Sat 59 60 NW 10 2433 2399 399 Blue 14
10 AM Sat 60 63 NW 10 2471 2432 432 Blue 17
11 AM Sat 63 67 W 8 2581 2493 493 Blue 21
12 Noon Sat 65 69 W 8 2748 2540 540 Blue 23
1 PM Sat 65 70 W 8 2836 2579 579 Blue 24
2 PM Sat 66 70 W 8 2836 2579 579 Blue 24
3 PM Sat 67 70 W 8 2836 2579 579 Blue 24
4 PM Sat 68 70 W 8 2836 2579 579 Blue 24
5 PM Sat 68 69 NW 12 2748 2540 540 Blue 23
6 PM Sat 66 66 NW 12 2541 2470 470 Blue 20
7 PM Sat 63 63 NW 12 2471 2432 432 Blue 17
8 PM Sat 58 58 NW 12 2411 2378 378 Blue 12
9 PM Sat 55 55 NW 12 2378 2345 345 Blue 9
10 PM Sat 54 54 NW 12 2367 2334 334 Blue 8
11 PM Sat 52 52 NW 7 2345 2299 299 Blue 6
12 Midnight Sun 50 50 NW 7 2323 2044 44 Blue 4
1 AM Sun 49 49 NW 7 2301 2000 0 Blue 3
2 AM Sun 48 48 NW 7 2257 2000 0 Blue 2
3 AM Sun 48 48 NW 7 2257 2000 0 Blue 2
4 AM Sun 49 49 NW 7 2301 2000 0 Blue 3
5 AM Sun 48 48 NW 6 2257 2000 0 Blue 2
6 AM Sun 47 47 NW 6 2046 2000 0 White 1
7 AM Sun 47 47 NW 6 2046 2000 0 White 1
8 AM Sun 55 55 NW 6 2378 2345 345 Blue 9
9 AM Sun 61 63 NW 6 2471 2432 432 Blue 17
10 AM Sun 63 66 NW 6 2541 2470 470 Blue 20
11 AM Sun 66 70 W 7 2836 2579 579 Blue 24
12 Noon Sun 68 73 W 7 3100 2831 831 Blue 27
1 PM Sun 69 75 W 7 3709 3007 1007 Blue 29
2 PM Sun 70 75 W 7 3709 3007 1007 Blue 29
3 PM Sun 71 75 W 7 3709 3007 1007 Blue 29
4 PM Sun 72 75 W 7 3709 3007 1007 Blue 29
5 PM Sun 72 73 NW 9 3100 2831 831 Blue 27
6 PM Sun 70 70 NW 9 2836 2579 579 Blue 24
7 PM Sun 66 66 NW 9 2541 2470 470 Blue 20
8 PM Sun 60 60 NW 9 2433 2399 399 Blue 14
9 PM Sun 56 56 NW 9 2389 2356 356 Blue 10
10 PM Sun 55 55 NW 9 2378 2345 345 Blue 9
11 PM Sun 53 53 NW 7 2356 2323 323 Blue 7
12 Midnight Mon 51 51 NW 7 2334 2255 255 Blue 5
1 AM Mon 49 49 NW 7 2301 2000 0 Blue 3
2 AM Mon 48 48 NW 7 2257 2000 0 Blue 2
3 AM Mon 48 48 NW 7 2257 2000 0 Blue 2
4 AM Mon 49 49 NW 7 2301 2000 0 Blue 3
5 AM Mon 48 48 NW 7 2257 2000 0 Blue 2
6 AM Mon 47 47 NW 7 2046 2000 0 White 1
7 AM Mon 47 47 NW 7 2046 2000 0 White 1
8 AM Mon 55 55 NW 7 2378 2345 345 Blue 9
9 AM Mon 61 62 NW 7 2455 2421 421 Blue 16
10 AM Mon 64 67 NW 7 2581 2493 493 Blue 21
11 AM Mon 67 71 W 7 2924 2655 655 Blue 25
12 Noon Mon 69 74 W 7 3278 2919 919 Blue 28
1 PM Mon 70 75 W 7 3709 3007 1007 Blue 29
2 PM Mon 71 75 W 7 3709 3007 1007 Blue 29
3 PM Mon 72 76 W 7 4134 3095 1095 Blue 30
4 PM Mon 73 75 W 7 3709 3007 1007 Blue 29
5 PM Mon 73 74 NW 8 3278 2919 919 Blue 28
6 PM Mon 71 71 NW 8 2924 2655 655 Blue 25
7 PM Mon 67 67 NW 8 2581 2493 493 Blue 21
8 PM Mon 61 61 NW 8 2444 2410 410 Blue 15
9 PM Mon 57 57 NW 8 2400 2367 367 Blue 11
10 PM Mon 56 56 NW 8 2389 2356 356 Blue 10
11 PM Mon 54 54 S 5 2367 2334 334 Blue 8
12 Midnight Tue 52 52 S 5 2345 2299 299 Blue 6
1 AM Tue 50 50 S 5 2323 2044 44 Blue 4
2 AM Tue 49 49 S 5 2301 2000 0 Blue 3
3 AM Tue 49 49 S 5 2301 2000 0 Blue 3
4 AM Tue 50 50 S 5 2323 2044 44 Blue 4
5 AM Tue 49 49 NW 5 2301 2000 0 Blue 3
6 AM Tue 48 48 NW 5 2257 2000 0 Blue 2
7 AM Tue 48 48 NW 5 2257 2000 0 Blue 2
8 AM Tue 56 56 NW 5 2389 2356 356 Blue 10
9 AM Tue 63 65 NW 5 2518 2454 454 Blue 19
10 AM Tue 65 68 NW 5 2659 2517 517 Blue 22
11 AM Tue 69 73 W 6 3100 2831 831 Blue 27
12 Noon Tue 71 76 W 6 4134 3095 1095 Blue 30
1 PM Tue 72 77 W 6 4551 3248 1248 Blue 31
2 PM Tue 73 78 W 6 4912 3675 1675 Blue 32
3 PM Tue 74 78 W 6 4912 3675 1675 Blue 32
4 PM Tue 75 77 W 6 4551 3248 1248 Blue 31
5 PM Tue 75 76 W 8 4134 3095 1095 Blue 30
6 PM Tue 73 73 W 8 3100 2831 831 Blue 27
7 PM Tue 69 69 W 8 2748 2540 540 Blue 23
8 PM Tue 64 64 W 8 2495 2443 443 Blue 18
9 PM Tue 60 60 W 8 2433 2399 399 Blue 14
10 PM Tue 59 59 W 8 2422 2389 389 Blue 13
11 PM Tue 57 57 N 6 2400 2367 367 Blue 11
12 Midnight Wed 55 55 N 6 2378 2345 345 Blue 9
1 AM Wed 53 53 N 6 2356 2323 323 Blue 7
2 AM Wed 52 52 N 6 2345 2299 299 Blue 6
3 AM Wed 52 52 N 6 2345 2299 299 Blue 6
4 AM Wed 53 53 N 6 2356 2323 323 Blue 7

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