Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
477
UXUS97 KPUB 211218
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0618 MDT Friday, June 21, 2024
This forecast is for the Air Force Academy for Friday, June 21, 2024:
If the trigger temperature of 67.2 F/19.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1007 ft/min (5.1 m/s)
Maximum height of thermals.................. 19729 ft MSL (12091 ft AGL)
Forecast maximum temperature................... 87.0 F/31.0 C
Time of trigger temperature.................... 0830 MDT
Time of overdevelopment........................ 1500 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 17566 ft MSL (9927 ft AGL)
Thermal soaring outlook for Saturday 06/22..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:34:07 / 20:28:25 MDT
Total possible sunshine........... 14 hr 54 min 18 sec (894 min 18 sec)
Altitude of sun at 13:01:16 MDT... 74.45 degrees
Upper air data from numerical model forecast valid on 06/21/2024 at 0600 MDT
Freezing level.................. 15621 ft MSL (7983 ft AGL)
Convective condensation level... 12635 ft MSL (4997 ft AGL)
Lifted condensation level....... 16681 ft MSL (9042 ft AGL)
Lifted index.................... -5.1
K index......................... +27.5
Height Temperature Wind Wind Spd Lapse Rate ConvectionT Thermal Lift Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft deg C deg F Index fpm m/s
--------------------------------------------------------------------------------
50000 -63.5 -82.3 235 47 24 4.0 2.2 M M M M M
45000 -56.6 -69.9 240 71 37 5.2 2.9 M M M M M
40000 -48.5 -55.3 240 77 39 6.4 3.5 M M M M M
38000 -44.6 -48.3 240 68 35 6.4 3.5 M M M M M
36000 -40.8 -41.4 235 59 31 6.6 3.6 M M M M M
34000 -35.9 -32.6 235 50 26 7.3 4.0 M M M M M
32000 -31.5 -24.7 235 43 22 8.3 4.6 M M M M M
30000 -26.5 -15.7 230 42 22 8.5 4.7 42.7 108.8 9.4 M M
29000 -24.0 -11.2 230 42 22 8.5 4.7 42.3 108.1 9.1 M M
28000 -21.6 -6.9 230 42 22 6.7 3.7 41.8 107.2 8.8 M M
27000 -19.6 -3.3 230 43 22 6.7 3.7 40.5 104.9 7.8 M M
26000 -17.7 0.1 230 44 23 6.8 3.7 39.4 103.0 7.0 M M
25000 -15.7 3.7 230 45 23 6.8 3.7 38.5 101.2 6.2 M M
24000 -13.8 7.2 225 45 23 6.5 3.6 37.2 99.0 5.1 M M
23000 -11.9 10.6 225 45 23 6.5 3.6 36.0 96.9 4.1 M M
22000 -10.1 13.8 220 45 23 6.4 3.5 35.0 95.0 3.2 M M
21000 -8.1 17.4 215 41 21 5.5 3.0 33.1 91.6 1.5 M M
20000 -6.5 20.3 215 38 20 5.5 3.0 31.7 89.0 0.2 M M
19500 -5.7 21.7 210 37 19 5.5 3.0 31.0 87.8 -0.4 983 5.0
19000 -4.9 23.2 210 36 19 5.5 3.0 30.3 86.5 -1.1 945 4.8
18500 -4.1 24.6 205 36 18 5.5 3.0 29.5 85.2 -1.7 907 4.6
18000 -3.4 25.9 205 35 18 5.3 2.9 28.8 83.9 -2.4 869 4.4
17500 -2.6 27.3 200 34 18 5.2 2.9 28.1 82.5 -3.2 832 4.2
17000 -1.9 28.6 200 33 17 5.2 2.8 27.3 81.2 -3.9 795 4.0
16500 -1.2 29.8 195 32 17 4.5 2.5 26.5 79.7 -4.7 759 3.9
16000 -0.5 31.1 195 31 16 4.5 2.4 25.7 78.2 -5.5 725 3.7
15500 0.2 32.4 195 30 16 6.4 3.5 24.9 76.9 -6.2 688 3.5
15000 1.2 34.2 195 29 15 6.6 3.6 24.4 76.0 -6.8 644 3.3
14500 2.2 36.0 195 28 15 6.4 3.5 23.9 75.1 -7.3 600 3.0
14000 3.0 37.4 195 28 14 6.4 3.5 23.4 74.1 -7.9 559 2.8
13500 3.9 39.0 195 27 14 6.6 3.6 22.8 73.1 -8.5 517 2.6
13000 4.9 40.8 200 27 14 7.2 4.0 22.4 72.3 -9.0 472 2.4
12500 5.9 42.6 205 27 14 6.3 3.4 21.9 71.5 -9.5 430 2.2
12000 6.8 44.2 205 28 14 7.3 4.0 21.5 70.6 -10.1 386 2.0
11750 7.4 45.3 205 28 14 6.9 3.8 21.3 70.3 -10.3 363 1.8
11500 7.8 46.0 210 28 14 4.4 2.4 21.0 69.7 -10.7 343 1.7
11250 8.1 46.6 210 28 14 5.4 3.0 20.5 68.9 -11.1 327 1.7
11000 8.6 47.5 210 27 14 7.4 4.1 20.3 68.6 -11.4 305 1.6
10750 9.0 48.2 210 27 14 7.5 4.1 20.1 68.2 -11.6 283 1.4
10500 9.5 49.1 210 26 14 5.1 2.8 19.9 67.8 -11.9 261 1.3
10250 9.8 49.6 210 25 13 4.9 2.7 19.5 67.0 -12.4 246 1.2
10000 10.3 50.5 210 24 12 7.6 4.2 19.2 66.6 -12.7 223 1.1
9750 10.8 51.4 210 23 12 6.6 3.6 19.0 66.3 -12.9 201 1.0
9500 11.3 52.3 210 21 11 8.1 4.4 18.8 65.9 -13.2 179 0.9
9250 11.9 53.4 210 20 10 7.8 4.3 18.7 65.7 -13.3 153 0.8
9000 12.3 54.1 210 19 10 4.2 2.3 18.4 65.2 -13.7 133 0.7
8750 12.6 54.7 215 18 9 3.1 1.7 18.0 64.3 -14.2 119 0.6
8500 12.8 55.0 220 18 9 3.6 2.0 17.5 63.5 -14.7 104 0.5
8250 13.3 55.9 230 15 8 1.4 0.8 16.6 61.8 -15.7 73 0.4
8000 13.2 55.8 235 11 6 -3.4 -1.9 15.7 60.3 -16.6 69 0.3
7750 13.1 55.6 250 7 3 5.3 2.9 14.9 58.9 -17.4 64 0.3
7500 M M M M M M M M M M M M
7250 M M M M M M M M M M M M
7000 M M M M M M M M M M M M
6750 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/21/2024 at 0900 MDT | 06/21/2024 at 1200 MDT
|
CAPE... 0.0 LI... +0.5 | CAPE... +177.5 LI... -0.0
CINH... 0.0 K Index... +26.8 | CINH... -61.4 K Index... +17.8
|
Height Temperature Wnd WndSpd Lapse Rate | Temperature Wnd WndSpd Lapse Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft | deg C deg F Dir kt m/s C/km F/kft
--------------------------------------------------------------------------------
50000 -63.6 -82.5 235 48 25 4.5 2.4 | -63.7 -82.7 235 51 26 4.6 2.5
45000 -56.1 -69.0 245 69 35 5.3 2.9 | -56.0 -68.8 245 72 37 5.3 2.9
40000 -47.8 -54.0 240 81 42 6.5 3.6 | -47.7 -53.9 240 86 44 7.0 3.8
38000 -43.9 -47.0 235 75 38 6.5 3.6 | -43.5 -46.3 235 79 41 7.0 3.8
36000 -40.0 -40.0 230 69 36 6.6 3.6 | -39.3 -38.7 235 73 38 6.8 3.7
34000 -35.5 -31.9 225 61 31 6.6 3.6 | -35.3 -31.5 230 69 35 6.0 3.3
32000 -31.5 -24.7 225 54 28 7.2 3.9 | -31.7 -25.1 225 66 34 6.1 3.3
30000 -27.1 -16.8 220 49 25 7.5 4.1 | -27.9 -18.2 225 59 31 6.4 3.5
29000 -24.9 -12.8 220 46 24 7.6 4.2 | -26.0 -14.8 220 56 29 6.4 3.5
28000 -22.7 -8.9 215 43 22 6.8 3.7 | -24.0 -11.2 220 53 27 7.4 4.0
27000 -20.8 -5.4 215 41 21 6.8 3.7 | -21.8 -7.2 220 50 26 7.4 4.1
26000 -18.8 -1.8 215 38 20 6.9 3.8 | -19.6 -3.3 220 47 24 7.4 4.1
25000 -16.8 1.8 220 35 18 7.0 3.9 | -17.4 0.7 225 44 23 7.2 4.0
24000 -14.6 5.7 225 36 18 7.4 4.1 | -15.4 4.3 225 42 21 6.9 3.8
23000 -12.5 9.5 235 38 19 7.4 4.1 | -13.4 7.9 230 39 20 7.1 3.9
22000 -10.3 13.5 240 40 20 7.3 4.0 | -11.4 11.5 230 36 19 7.4 4.1
21000 -8.3 17.1 240 40 21 6.9 3.8 | -9.2 15.4 240 34 18 7.8 4.3
20000 -5.8 21.6 240 40 21 6.9 3.8 | -6.3 20.7 250 32 17 7.8 4.3
19500 -4.8 23.4 245 40 21 6.7 3.7 | -5.2 22.6 255 32 17 7.4 4.1
19000 -3.9 25.0 245 40 21 5.7 3.1 | -4.2 24.4 260 29 15 6.5 3.6
18500 -3.1 26.4 240 40 20 5.8 3.2 | -3.2 26.2 260 26 13 6.5 3.6
18000 -2.2 28.0 240 40 20 5.7 3.1 | -2.1 28.2 265 23 12 6.9 3.8
17500 -1.4 29.5 240 40 20 5.7 3.1 | -1.1 30.0 265 21 11 6.9 3.8
17000 -0.6 30.9 240 40 20 5.7 3.1 | -0.1 31.8 260 18 9 6.7 3.7
16500 0.2 32.4 240 40 20 5.4 3.0 | 0.8 33.4 265 17 9 6.0 3.3
16000 1.0 33.8 240 40 21 5.4 3.0 | 1.7 35.1 265 17 9 6.1 3.3
15500 1.7 35.1 235 40 21 5.5 3.0 | 2.6 36.7 265 16 8 5.8 3.2
15000 2.5 36.5 235 40 21 5.6 3.1 | 3.4 38.1 270 17 9 5.9 3.2
14500 3.3 37.9 235 40 21 6.9 3.8 | 4.3 39.7 270 17 9 6.3 3.4
14000 4.5 40.1 230 40 20 7.8 4.3 | 5.2 41.4 270 17 9 6.5 3.6
13500 5.6 42.1 230 39 20 7.4 4.1 | 6.1 43.0 275 17 9 6.8 3.7
13000 6.6 43.9 230 37 19 6.2 3.4 | 7.2 45.0 275 18 9 7.2 3.9
12500 7.5 45.5 230 35 18 6.4 3.5 | 8.1 46.6 275 18 9 6.5 3.6
12000 8.4 47.1 235 32 17 6.5 3.6 | 9.1 48.4 280 19 10 6.9 3.8
11750 8.9 48.0 235 31 16 6.2 3.4 | 9.7 49.5 280 19 10 7.1 3.9
11500 9.3 48.7 240 29 15 3.7 2.1 | 10.2 50.4 280 19 10 7.5 4.1
11250 9.5 49.1 240 29 15 3.2 1.7 | 10.6 51.1 280 19 10 6.3 3.5
11000 9.8 49.6 245 27 14 4.3 2.3 | 11.0 51.8 280 19 10 5.8 3.2
10750 10.1 50.2 245 26 13 4.2 2.3 | 11.4 52.5 280 19 10 5.0 2.8
10500 10.4 50.7 250 24 12 3.6 1.9 | 11.8 53.2 275 19 10 8.8 4.8
10250 10.6 51.1 250 24 12 1.9 1.0 | 12.5 54.5 275 18 9 10.9 6.0
10000 10.7 51.3 255 22 11 1.4 0.7 | 13.1 55.6 270 16 8 8.5 4.6
9750 10.8 51.4 255 20 10 1.6 0.9 | 13.8 56.8 265 15 8 9.3 5.1
9500 10.9 51.6 255 19 10 1.2 0.7 | 14.4 57.9 255 13 7 8.3 4.6
9250 11.0 51.8 260 17 9 2.0 1.1 | 15.0 59.0 250 12 6 8.8 4.8
9000 11.2 52.2 260 17 9 3.9 2.1 | 15.7 60.3 245 12 6 10.5 5.8
8750 11.5 52.7 265 16 8 3.8 2.1 | 16.5 61.7 245 11 6 10.5 5.8
8500 11.7 53.1 265 16 8 5.1 2.8 | 17.3 63.1 245 10 5 10.6 5.8
8250 12.2 54.0 270 15 8 9.6 5.3 | 18.1 64.6 240 10 5 12.2 6.7
8000 13.2 55.8 270 14 7 16.4 9.0 | 19.2 66.6 240 10 5 18.8 10.3
7750 14.6 58.3 270 13 6 22.0 12.1 | 20.9 69.6 235 9 5 26.6 14.6
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
06/21/2024 at 1500 MDT | 06/21/2024 at 1800 MDT
|
CAPE... +594.2 LI... -3.4 | CAPE... +707.8 LI... -3.6
CINH... -1.8 K Index... +26.7 | CINH... -6.7 K Index... +34.4
|
Height Temperature Wnd WndSpd Lapse Rate | Temperature Wnd WndSpd Lapse Rate
ft MSL deg C deg F Dir kt m/s C/km F/kft | deg C deg F Dir kt m/s C/km F/kft
--------------------------------------------------------------------------------
50000 -63.3 -81.9 235 52 27 4.8 2.6 | -63.4 -82.1 240 54 28 4.4 2.4
45000 -55.7 -68.3 245 73 38 5.6 3.0 | -55.8 -68.4 245 75 39 5.9 3.3
40000 -47.1 -52.8 240 94 48 6.9 3.8 | -46.6 -51.9 245 95 49 7.3 4.0
38000 -42.9 -45.2 240 86 44 6.9 3.8 | -42.2 -44.0 245 89 46 7.3 4.0
36000 -38.8 -37.8 235 78 40 6.7 3.7 | -37.8 -36.0 245 84 43 7.0 3.8
34000 -34.8 -30.6 230 75 39 5.9 3.3 | -33.8 -28.8 240 75 38 5.8 3.2
32000 -31.2 -24.2 230 73 37 6.1 3.3 | -30.3 -22.5 240 66 34 5.8 3.2
30000 -27.5 -17.5 230 67 34 6.2 3.4 | -26.9 -16.4 240 61 31 5.7 3.1
29000 -25.6 -14.1 230 64 33 6.2 3.4 | -25.2 -13.4 240 58 30 5.7 3.1
28000 -23.7 -10.7 230 60 31 6.6 3.6 | -23.5 -10.3 240 56 29 6.8 3.7
27000 -21.8 -7.2 230 55 28 6.6 3.6 | -21.4 -6.5 245 54 28 6.8 3.8
26000 -19.8 -3.6 230 50 26 6.6 3.6 | -19.4 -2.9 245 53 27 6.9 3.8
25000 -17.8 -0.0 230 45 23 6.8 3.7 | -17.3 0.9 245 51 26 6.8 3.7
24000 -15.6 3.9 230 43 22 7.4 4.1 | -15.4 4.3 245 47 24 6.6 3.6
23000 -13.4 7.9 230 41 21 7.4 4.1 | -13.5 7.7 240 42 22 6.8 3.7
22000 -11.2 11.8 230 39 20 6.9 3.8 | -11.7 10.9 240 38 19 7.1 3.9
21000 -9.6 14.7 240 34 17 5.6 3.1 | -9.6 14.7 245 33 17 7.1 3.9
20000 -7.6 18.3 255 28 15 6.1 3.4 | -7.6 18.3 250 29 15 7.2 4.0
19500 -6.9 19.6 260 27 14 6.8 3.7 | -6.6 20.1 250 26 14 7.3 4.0
19000 -5.7 21.7 265 25 13 7.6 4.2 | -5.6 21.9 255 24 13 6.9 3.8
18500 -4.5 23.9 265 24 12 7.7 4.2 | -4.1 24.6 250 22 11 6.9 3.8
18000 -3.4 25.9 265 23 12 7.3 4.0 | -3.1 26.4 250 20 10 6.8 3.7
17500 -2.4 27.7 265 23 12 7.4 4.1 | -2.1 28.2 250 18 9 6.9 3.8
17000 -1.4 29.5 265 22 11 7.5 4.1 | -1.2 29.8 250 16 8 7.2 4.0
16500 -0.4 31.3 270 20 10 7.3 4.0 | -0.1 31.8 245 15 8 7.9 4.3
16000 0.5 32.9 270 19 10 7.3 4.0 | 1.1 34.0 245 14 7 7.8 4.3
15500 1.7 35.1 275 17 9 9.3 5.1 | 2.3 36.1 240 13 7 9.4 5.2
15000 3.0 37.4 270 14 7 9.2 5.0 | 3.7 38.7 235 12 6 9.3 5.1
14500 4.3 39.7 270 12 6 9.4 5.1 | 5.0 41.0 235 12 6 9.7 5.3
14000 5.7 42.3 270 11 6 9.4 5.2 | 6.5 43.7 230 12 6 9.8 5.4
13500 7.1 44.8 270 11 5 9.6 5.2 | 7.9 46.2 225 11 6 9.0 4.9
13000 8.5 47.3 260 8 4 9.5 5.2 | 9.1 48.4 215 12 6 9.0 4.9
12500 9.9 49.8 260 7 4 9.0 4.9 | 10.6 51.1 210 13 7 9.6 5.3
12000 11.2 52.2 245 6 3 8.4 4.6 | 11.7 53.1 205 13 7 5.9 3.2
11750 11.8 53.2 230 5 3 9.5 5.2 | 12.2 54.0 200 14 7 8.9 4.9
11500 12.6 54.7 225 5 3 10.8 5.9 | 13.0 55.4 195 14 7 12.1 6.6
11250 13.3 55.9 220 5 2 9.4 5.1 | 13.8 56.8 190 14 7 9.0 5.9
11000 14.0 57.2 210 5 2 8.7 4.8 | 14.4 57.9 185 14 7 7.7 4.2
10750 14.6 58.3 205 5 3 8.1 4.4 | 15.0 59.0 180 15 7 6.6 3.6
10500 15.3 59.5 200 5 3 11.2 6.2 | 15.5 59.9 180 15 8 12.2 6.7
10250 16.2 61.2 195 5 3 12.0 6.6 | 16.7 62.1 175 15 8 13.4 7.4
10000 17.0 62.6 190 5 3 9.1 5.0 | 17.4 63.3 175 15 8 8.3 4.6
9750 17.7 63.9 185 5 3 10.4 5.7 | 18.1 64.6 170 15 8 10.3 5.6
9500 18.4 65.1 180 5 3 8.2 4.5 | 18.8 65.8 170 15 8 7.5 4.1
9250 19.0 66.2 180 5 3 8.7 4.8 | 19.3 66.7 170 15 8 8.2 4.5
9000 19.8 67.6 175 5 3 11.3 6.2 | 20.1 68.2 170 15 8 11.3 6.2
8750 20.6 69.1 175 6 3 11.0 6.1 | 20.9 69.6 165 15 8 11.1 6.1
8500 21.4 70.5 170 6 3 10.7 5.9 | 21.7 71.1 165 15 8 10.4 5.7
8250 22.2 72.0 170 6 3 10.6 5.8 | 22.4 72.3 165 15 8 8.6 4.7
8000 23.1 73.6 165 6 3 16.4 9.0 | 23.1 73.6 165 14 7 11.7 6.4
7750 24.6 76.3 165 6 3 24.6 13.5 | 24.2 75.6 160 13 6 18.1 9.9
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC). It is not continuously monitored nor updated after its initial
issuance.
The information contained herein is based on rawinsonde observation and/or
numerical weather prediction model data taken near the Air Force Academy
in Colorado Springs, Colorado at
North Latitude: 38 deg 58 min 48.000 sec
West Longitude: 104 deg 49 min 12.000 sec
Elevation: 6572 feet (2003 meters)
and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains. Note that some elevations in numerical weather
prediction models differ from actual station elevations, which can lead to
data which appear to be below ground. Erroneous data such as these should
not be used.
The content and format of this report as well as the issuance times are subject
to change without prior notice. Comments and suggestions are welcome and should
be directed to one of the addresses or phone numbers shown at the bottom of this
page. To expedite a response to comments, be sure to mention your interest in
the soaring forecast.
DEFINITIONS:
CAPE (Convective Available Potential Energy) - An integrated measure of the
energy available for convective development, also known as the positive
area on a thermodynamic diagram. Units are Joules per kilogram. Larger
values are indicative of greater instability and the possibility of
stronger convective activity, including thunderstorms. Values around or
greater than 1000 suggest the possibility of severe weather should
convective activity develop.
CIN (Convective Inhibition) - An integrated measure of the amount of energy
needed to initiate convective activity, also known as the negative area on
a thermodynamic diagram. Units are Joules per kilogram. The more negative
this number, the more energy is required to initiate convection. This
inhibitive energy can be overcome through surface heating, cooling aloft,
lifting mechanisms (orographic, frontal, gravity waves, etc.)
Convective Condensation Level - The height to which an air parcel possessing the
average saturation mixing ratio in the lowest 4000 feet of the airmass,
if heated sufficiently from below, will rise dry adiabatically until it
just becomes saturated. It estimates the base of cumulus clouds that are
produced by surface heating only.
Convection Temperature (ConvectionT) - The surface temperature required to make
the airmass dry adiabatic up to the given level. It can be considered a
"trigger temperature" for that level.
Freezing Level - The height where the temperature is zero degrees Celsius.
Height of Stable Layer - The height (between 12,000 and 18,000 feet above
mean sea level) where the smallest lapse rate exists. The location and
existence of this feature is important in the generation of mountain
waves.
K Index - A measure of stability which combines the temperature difference
between approximately 5,000 and 18,000 feet above the surface, the amount
of moisture at approximately 5,000 feet above the surface, and a measure
of the dryness at approximately 10,000 feet above the surface. Larger
positive numbers indicate more instability and a greater likelihood of
thunderstorm development. One interpretation of K index values regarding
soaring in the western United States is given in WMO Technical Note 158
and is reproduced in the following table:
below -10 no or weak thermals
-10 to 5 dry thermals or 1/8 cumulus with moderate thermals
5 to 15 good soaring conditions
15 to 20 good soaring conditions with occasional showers
20 to 30 excellent soaring conditions, but increasing
probability of showers and thunderstorms
above 30 more than 60 percent probability of thunderstorms
Lapse Rate - The change with height of the temperature. Negative values indicate
inversions.
Lifted Condensation Level - The height to which an air parcel possessing the
average dew point in the lowest 4000 feet of the airmass and the forecast
maximum temperature must be lifted dry adiabatically to attain saturation.
Lifted Index (LI) - The difference between the environmental temperature at a
level approximately 18,000 feet above the surface and the temperature of
an air parcel lifted dry adiabatically from the surface to its lifted
condensation level and then pseudoadiabatically thereafter to this same
level. The parcel`s initial temperature is the forecast maximum
temperature and its dew point is the average dew point in the lowest 4000
feet of the airmass. Negative values are indicative of instability with
positive values showing stable conditions.
Lift Rate - An experimental estimate of the strength of thermals. It is
computed the same way as the maximum rate of lift but uses the actual
level rather than the maximum height of thermals in the calculation.
Also, none of the empirical adjustments based on cloudiness and K-index
are applied to these calculations.
Maximum Height of Thermals - The height where the dry adiabat through the
forecast maximum temperature intersects the environmental temperature.
Maximum Rate of Lift - An estimate of the maximum strength of thermals. It
is computed from an empirical formula which combines the expected maximum
height of thermals with the difference in the environmental temperatures
between the maximum height of thermals and the temperature 4,000 feet
above the ground. After this computation, further empirical adjustments
are made based on the value of the K-index and the amount and opacity of
middle and high level cloudiness expected between the time of trigger
temperature and the time of overdevelopment.
Middle/High Clouds - The amount and opacity of middle (altostratus, altocumulus)
or high (cirrus, cirrostratus, cirrocumulus) clouds. Broken means that
between 60% and 90% of the sky is covered by the cloud, with overcast
conditions occurring when more than 90% of the sky is covered by the cloud.
Thin implies that the clouds are predominantly transparent, meaning that
some sunlight is reaching the ground, in contrast to opaque which suggests
that little sunlight is reaching the ground.
Potential Height of Wave - The minimum of the following two heights:
1. Level above the height of stable layer (or 14,000 feet if none exists)
where the wind direction changes by 30 degrees or more
2. Level above the height of stable layer (or 14,000 feet if none exists)
where the wind speed no longer increases with height
PVA/NVA - Positive vorticity advection (PVA)/negative vorticity advection (NVA)
on the 500 millibar isobaric surface (approximately 18,000 feet above mean
sea level). Weak PVA has been shown to assist in mountain wave soaring.
Soaring Window - The time between the time the trigger temperature is reached
and the time of overdevelopment.
Thermal Index - The difference between the environmental temperature and the
temperature at a particular level determined by following the dry adiabat
through the forecast maximum temperature up to that level. Negative values
are indicative of thermal lift.
Thermal Soaring Index - An adjective rating (for sailplanes) based on the
computed maximum rate of lift, and the wind speed and middle and high
cloud cover expected during the soaring window (the time of the trigger
temperature and the time of overdevelopment) according to the following:
Maximum rate of lift Adjective Rating
>= 800 fpm Excellent
>= 400 and < 800 fpm Good
>= 200 and < 400 fpm Fair
< 200 fpm Poor
Time of Overdevelopment - The time one or more of the following phenomena,
which essentially shut off thermal lift, is expected to occur:
1. formation of broken to overcast convective cloud cover
2. formation of scattered to numerous downbursts
3. initiation of widespread precipitation
Time of Trigger Temperature - The time the surface temperature is expected to
reach the trigger temperature.
Trigger Temperature - The surface temperature required to make the first 4000
feet of the atmosphere dry adiabatic.
Wave Soaring Index - An empirical, adjective rating (for sailplanes) which
attempts to combine a variety of phenomena important in mountain wave
soaring into a single index number. Objective points are assigned to
these phenomena: wind speed and direction at 14,000 ft MSL, the static
stability in the 12,000-18,000 ft MSL layer, the wind speed gradient above
the stable layer, jet stream location and frontal and upper trough
movements.
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