Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
507
UXUS97 KPUB 161214
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0614 MDT Friday, May 16, 2025
This forecast is for the Air Force Academy for Friday, May 16, 2025:
If the trigger temperature of 47.1 F/8.4 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 1289 ft/min (6.5 m/s)
Maximum height of thermals.................. 23926 ft MSL (16284 ft AGL)
Forecast maximum temperature................... 69.0 F/21.0 C
Time of trigger temperature.................... 0615 MDT
Time of overdevelopment........................ 2000 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ More than 30 mph
Height of the -3 thermal index................. 20547 ft MSL (12905 ft AGL)
Thermal soaring outlook for Saturday 05/17..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:45:07 / 20:06:15 MDT
Total possible sunshine........... 14 hr 21 min 8 sec (861 min 8 sec)
Altitude of sun at 12:55:41 MDT... 70.29 degrees
Upper air data from numerical model forecast valid on 05/16/2025 at 0600 MDT
Freezing level.................. 10121 ft MSL (2479 ft AGL)
Convective condensation level... 15522 ft MSL (7880 ft AGL)
Lifted condensation level....... 19170 ft MSL (11527 ft AGL)
Lifted index.................... -3.6
K index......................... +5.7
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 -54.0 -65.2 245 32 16 1.6 0.9 M M M M M
45000 -51.7 -61.1 255 39 20 -0.1 -0.1 M M M M M
40000 -52.9 -63.2 270 59 30 -0.7 -0.4 M M M M M
38000 -52.6 -62.7 270 63 32 1.4 0.8 M M M M M
36000 -51.7 -61.1 270 64 33 1.4 0.8 M M M M M
34000 -50.5 -58.9 270 66 34 5.2 2.9 M M M M M
32000 -47.6 -53.7 280 69 36 4.9 2.7 M M M M M
30000 -44.3 -47.7 285 73 38 8.3 4.6 24.4 75.9 2.9 M M
29000 -41.9 -43.4 285 73 38 8.1 4.4 23.6 74.5 2.4 M M
28000 -39.5 -39.1 280 73 38 8.1 4.4 23.0 73.4 1.9 M M
27000 -37.1 -34.8 280 73 38 8.1 4.4 22.5 72.5 1.5 M M
26000 -34.6 -30.3 280 73 37 8.1 4.5 21.8 71.2 1.0 M M
25000 -31.6 -24.9 285 72 37 8.1 4.5 21.0 69.9 0.4 M M
24000 -29.1 -20.4 285 71 37 7.8 4.3 20.6 69.0 -0.0 1485 7.5
23000 -27.0 -16.6 285 69 35 7.1 3.9 19.6 67.2 -0.9 1392 7.1
22000 -24.9 -12.8 290 67 34 7.1 3.9 18.6 65.5 -1.7 1299 6.6
21000 -22.8 -9.0 290 64 33 6.3 3.5 17.7 63.9 -2.5 1207 6.1
20000 -21.0 -5.8 290 61 31 6.1 3.4 16.4 61.5 -3.7 1122 5.7
19500 -20.1 -4.2 295 59 31 6.1 3.4 15.8 60.4 -4.3 1080 5.5
19000 -19.1 -2.4 295 58 30 6.2 3.4 15.2 59.4 -4.8 1038 5.3
18500 -18.2 -0.8 295 56 29 6.3 3.5 14.7 58.4 -5.3 995 5.1
18000 -17.3 0.9 295 55 28 6.5 3.6 14.1 57.3 -5.9 951 4.8
17500 -16.3 2.7 295 54 28 6.5 3.6 13.5 56.4 -6.4 908 4.6
17000 -15.3 4.5 300 52 27 7.2 4.0 13.1 55.5 -6.9 862 4.4
16500 -14.2 6.4 300 51 26 7.2 3.9 12.6 54.7 -7.3 815 4.1
16000 -13.1 8.4 300 50 26 7.1 3.9 12.2 54.0 -7.8 769 3.9
15500 -12.1 10.2 300 48 25 7.1 3.9 11.8 53.2 -8.2 722 3.7
15000 -11.0 12.2 300 47 24 7.1 3.9 11.4 52.4 -8.7 676 3.4
14500 -10.0 14.0 300 46 24 7.2 3.9 10.9 51.6 -9.2 630 3.2
14000 -8.9 16.0 300 45 23 7.3 4.0 10.5 50.9 -9.6 583 3.0
13500 -7.8 18.0 300 43 22 7.6 4.2 10.1 50.2 -10.0 536 2.7
13000 -6.7 19.9 300 41 21 8.8 4.8 9.8 49.6 -10.5 488 2.5
12500 -5.4 22.3 300 39 20 7.1 3.9 9.7 49.4 -10.6 433 2.2
12000 -4.5 23.9 300 36 18 6.4 3.5 9.1 48.4 -11.3 391 2.0
11750 -4.0 24.8 300 33 17 7.6 4.1 8.9 48.0 -11.5 369 1.9
11500 -3.4 25.9 300 29 15 8.1 4.5 8.8 47.8 -11.7 343 1.7
11250 -2.8 27.0 305 24 13 7.7 4.2 8.6 47.5 -11.9 318 1.6
11000 -2.2 28.0 305 20 10 7.8 4.3 8.5 47.2 -12.0 294 1.5
10750 -1.7 28.9 305 18 9 7.7 4.2 8.3 47.0 -12.2 269 1.4
10500 -1.1 30.0 310 20 11 7.7 4.2 8.1 46.7 -12.4 245 1.2
10250 -0.5 31.1 310 23 12 7.8 4.3 8.0 46.4 -12.6 220 1.1
10000 0.0 32.0 310 24 12 7.6 4.2 7.8 46.1 -12.8 196 1.0
9750 0.6 33.1 305 25 13 6.7 3.7 7.6 45.7 -13.1 173 0.9
9500 1.0 33.8 305 25 13 6.4 3.5 7.4 45.3 -13.4 152 0.8
9250 1.5 34.7 300 26 13 6.5 3.5 7.1 44.8 -13.7 130 0.7
9000 1.9 35.4 300 26 13 5.8 3.2 6.9 44.4 -14.0 110 0.6
8750 2.7 36.9 295 23 12 4.5 2.5 6.2 43.2 -14.7 71 0.4
8500 3.1 37.6 290 22 11 9.2 5.1 5.9 42.6 -15.1 51 0.3
8250 3.8 38.8 285 20 10 0.5 0.3 5.8 42.5 -15.2 25 0.1
8000 2.7 36.9 285 14 7 -27.6 -15.1 4.0 39.3 -17.1 50 0.3
7750 1.6 34.9 275 7 4 26.3 14.4 2.3 36.1 -18.9 74 0.4
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 * * * * * *
05/16/2025 at 0900 MDT | 05/16/2025 at 1200 MDT
|
CAPE... 0.0 LI... +2.1 | CAPE... +0.6 LI... +1.4
CINH... 0.0 K Index... -4.8 | CINH... 0.0 K Index... +6.9
|
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 -55.0 -67.0 250 30 15 1.7 0.9 | -55.9 -68.6 250 26 13 1.1 0.6
45000 -52.6 -62.7 265 38 20 -0.5 -0.3 | -54.4 -65.9 275 30 15 -1.3 -0.7
40000 -54.0 -65.2 275 56 29 -0.9 -0.5 | -56.8 -70.2 285 51 26 -1.5 -0.8
38000 -53.4 -64.1 280 59 31 2.4 1.3 | -55.5 -67.9 290 58 30 4.0 2.2
36000 -51.9 -61.4 285 60 31 2.4 1.3 | -53.1 -63.6 290 63 32 4.0 2.2
34000 -50.0 -58.0 290 63 32 6.2 3.4 | -50.0 -58.0 295 68 35 7.8 4.3
32000 -46.4 -51.5 290 69 36 6.1 3.4 | -45.3 -49.5 295 70 36 7.9 4.3
30000 -42.6 -44.7 290 73 38 7.0 3.9 | -40.5 -40.9 295 71 36 8.1 4.4
29000 -40.5 -40.9 290 71 36 7.0 3.9 | -38.1 -36.6 295 70 36 8.1 4.4
28000 -38.4 -37.1 285 69 35 7.0 3.9 | -35.7 -32.3 295 69 36 8.1 4.4
27000 -36.3 -33.3 285 67 34 7.3 4.0 | -33.3 -27.9 295 68 35 7.3 4.0
26000 -33.9 -29.0 285 65 34 8.0 4.4 | -31.3 -24.3 295 66 34 6.6 3.6
25000 -31.5 -24.7 285 64 33 8.0 4.4 | -28.8 -19.8 295 62 32 6.6 3.6
24000 -28.5 -19.3 280 63 32 7.6 4.2 | -26.8 -16.2 295 59 31 6.3 3.5
23000 -26.3 -15.3 285 61 32 7.2 3.9 | -25.0 -13.0 295 57 30 6.2 3.4
22000 -24.2 -11.6 285 60 31 7.2 4.0 | -23.1 -9.6 295 55 28 6.2 3.4
21000 -22.1 -7.8 290 57 29 6.5 3.6 | -21.3 -6.3 295 53 27 5.9 3.2
20000 -20.1 -4.2 290 52 27 6.5 3.5 | -19.5 -3.1 295 50 26 5.9 3.2
19500 -19.2 -2.6 295 50 26 6.5 3.5 | -18.6 -1.5 300 48 25 5.9 3.2
19000 -18.2 -0.8 295 47 24 6.5 3.5 | -17.8 -0.0 300 47 24 5.9 3.2
18500 -17.2 1.0 295 45 23 6.7 3.7 | -16.8 1.8 300 45 23 6.5 3.6
18000 -16.2 2.8 300 43 22 6.9 3.8 | -15.9 3.4 305 45 23 6.7 3.7
17500 -15.1 4.8 305 41 21 6.9 3.8 | -14.9 5.2 305 44 23 6.8 3.7
17000 -14.1 6.6 305 40 21 6.5 3.6 | -13.8 7.2 305 43 22 7.0 3.8
16500 -13.2 8.2 305 40 20 6.5 3.6 | -12.8 9.0 305 42 22 7.1 3.9
16000 -12.2 10.0 310 40 20 6.3 3.4 | -11.8 10.8 305 40 21 5.9 3.2
15500 -11.3 11.7 310 40 21 6.3 3.4 | -11.0 12.2 305 38 20 6.0 3.3
15000 -10.4 13.3 310 41 21 6.1 3.3 | -10.1 13.8 305 35 18 6.3 3.5
14500 -9.5 14.9 310 41 21 5.9 3.3 | -9.2 15.4 300 30 15 6.6 3.6
14000 -8.7 16.3 305 41 21 6.1 3.3 | -8.3 17.1 300 24 12 8.2 4.5
13500 -7.8 18.0 305 41 21 6.5 3.5 | -6.8 19.8 300 22 11 9.7 5.3
13000 -6.8 19.8 305 41 21 7.6 4.2 | -5.4 22.3 300 19 10 12.1 6.7
12500 -5.7 21.7 300 41 21 6.2 3.4 | -3.7 25.3 300 18 9 8.0 4.4
12000 -4.9 23.2 300 38 20 6.3 3.4 | -2.5 27.5 305 18 9 9.0 4.9
11750 -4.4 24.1 300 37 19 7.9 4.4 | -1.7 28.9 305 18 9 10.1 5.5
11500 -3.8 25.2 300 34 18 8.9 4.9 | -1.0 30.2 305 18 9 10.0 5.5
11250 -3.2 26.2 300 32 16 8.8 4.8 | -0.2 31.6 305 17 9 9.7 5.3
11000 -2.5 27.5 300 30 15 8.8 4.8 | 0.5 32.9 305 17 9 9.8 5.4
10750 -1.9 28.6 300 27 14 9.0 4.9 | 1.2 34.2 305 17 9 9.8 5.4
10500 -1.2 29.8 300 25 13 8.9 4.9 | 2.0 35.6 305 17 9 9.8 5.4
10250 -0.5 31.1 300 22 11 10.4 5.7 | 2.7 36.9 305 17 9 10.2 5.6
10000 0.3 32.5 300 21 11 10.9 6.0 | 3.5 38.3 310 17 9 10.3 5.7
9750 1.0 33.8 300 19 10 9.6 5.3 | 4.2 39.6 310 16 8 10.2 5.6
9500 1.7 35.1 300 18 9 9.2 5.0 | 5.0 41.0 310 16 8 10.0 5.5
9250 2.4 36.3 300 17 9 10.1 5.6 | 5.8 42.4 310 16 8 10.8 5.9
9000 3.2 37.8 300 16 8 11.0 6.0 | 6.6 43.9 310 16 8 10.8 5.9
8750 4.0 39.2 300 15 8 10.4 5.7 | 7.4 45.3 310 16 8 10.0 5.5
8500 4.8 40.6 300 15 8 10.7 5.9 | 8.1 46.6 310 15 8 9.8 5.4
8250 5.6 42.1 300 14 7 9.3 5.1 | 8.9 48.0 315 15 8 11.3 6.2
8000 6.4 43.5 305 13 7 14.3 7.8 | 10.0 50.0 315 15 8 20.4 11.2
7750 9.4 48.9 305 10 5 3.7 2.0 | 13.8 56.8 315 13 6 14.1 7.7
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
05/16/2025 at 1500 MDT | 05/16/2025 at 1800 MDT
|
CAPE... +33.2 LI... +0.5 | CAPE... +36.6 LI... -0.6
CINH... 0.0 K Index... +16.4 | CINH... -0.6 K Index... +19.6
|
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 -56.2 -69.2 245 30 15 0.4 0.2 | -57.5 -71.5 250 31 16 -0.6 -0.3
45000 -55.8 -68.4 255 42 22 -2.5 -1.3 | -58.4 -73.1 260 44 23 -0.8 -0.4
40000 -59.7 -75.5 275 66 34 -2.2 -1.2 | -59.6 -75.3 270 61 31 -0.6 -0.3
38000 -57.5 -71.5 280 68 35 6.0 3.3 | -56.8 -70.2 270 62 32 6.2 3.4
36000 -53.9 -65.0 280 65 34 6.0 3.3 | -53.1 -63.6 265 62 32 6.2 3.4
34000 -49.8 -57.6 285 62 32 8.4 4.6 | -48.9 -56.0 265 59 30 8.1 4.4
32000 -44.8 -48.6 290 59 31 8.3 4.6 | -44.0 -47.2 265 51 26 8.1 4.4
30000 -39.8 -39.6 290 57 29 8.6 4.7 | -39.1 -38.4 270 45 23 8.4 4.6
29000 -37.2 -35.0 290 55 28 8.6 4.7 | -36.6 -33.9 270 43 22 8.4 4.6
28000 -34.6 -30.3 295 53 27 8.6 4.7 | -34.1 -29.4 270 41 21 8.4 4.6
27000 -32.1 -25.8 295 51 26 7.5 4.1 | -31.6 -24.9 275 40 20 7.8 4.3
26000 -29.9 -21.8 295 49 25 7.4 4.0 | -28.7 -19.7 275 39 20 7.8 4.3
25000 -27.2 -17.0 290 46 24 7.4 4.1 | -26.3 -15.3 280 39 20 7.8 4.3
24000 -25.0 -13.0 290 44 22 6.7 3.7 | -24.1 -11.4 280 38 20 6.0 3.3
23000 -23.0 -9.4 290 41 21 6.8 3.7 | -22.3 -8.1 280 36 19 6.2 3.4
22000 -21.0 -5.8 290 39 20 6.8 3.7 | -20.5 -4.9 280 35 18 6.2 3.4
21000 -19.1 -2.4 290 37 19 5.4 2.9 | -18.8 -1.8 280 33 17 4.8 2.6
20000 -17.5 0.5 290 35 18 5.5 3.0 | -17.4 0.7 280 32 17 4.8 2.7
19500 -16.7 1.9 290 35 18 5.5 3.0 | -16.7 1.9 275 32 16 4.8 2.7
19000 -15.9 3.4 290 34 18 5.6 3.1 | -16.0 3.2 275 31 16 4.8 2.6
18500 -15.1 4.8 290 34 17 4.2 2.3 | -15.1 4.8 275 30 15 6.4 3.5
18000 -14.5 5.9 285 33 17 4.4 2.4 | -14.2 6.4 275 28 15 6.3 3.5
17500 -13.9 7.0 285 33 17 5.5 3.0 | -13.3 8.1 270 27 14 7.6 4.2
17000 -13.0 8.6 280 29 15 6.5 3.6 | -12.1 10.2 270 24 12 8.3 4.5
16500 -12.0 10.4 275 26 13 6.8 3.7 | -10.9 12.4 270 21 11 8.6 4.7
16000 -10.8 12.6 275 23 12 9.7 5.3 | -9.5 14.9 270 20 10 9.5 5.2
15500 -9.4 15.1 275 21 11 9.5 5.2 | -8.1 17.4 270 18 9 9.4 5.2
15000 -8.0 17.6 275 19 10 9.7 5.3 | -6.7 19.9 270 18 9 9.8 5.4
14500 -6.5 20.3 275 19 10 9.7 5.3 | -5.2 22.6 270 17 9 9.8 5.4
14000 -5.0 23.0 275 18 9 9.9 5.4 | -3.7 25.3 270 17 9 9.9 5.5
13500 -3.5 25.7 280 17 9 10.1 5.5 | -2.2 28.0 275 16 8 10.0 5.5
13000 -2.1 28.2 280 16 8 13.2 7.2 | -0.7 30.7 275 16 8 11.1 6.1
12500 -0.3 31.5 285 15 8 7.4 4.1 | 0.8 33.4 275 15 8 8.3 4.5
12000 0.9 33.6 285 15 8 8.8 4.8 | 2.1 35.8 280 14 7 9.4 5.1
11750 1.6 34.9 285 14 7 9.5 5.2 | 2.8 37.0 280 14 7 10.5 5.7
11500 2.3 36.1 285 14 7 9.8 5.4 | 3.6 38.5 285 13 7 10.0 5.5
11250 3.1 37.6 290 14 7 10.1 5.6 | 4.3 39.7 285 13 7 10.1 5.5
11000 3.8 38.8 290 14 7 9.8 5.4 | 5.1 41.2 285 13 7 9.7 5.3
10750 4.6 40.3 290 14 7 9.3 5.1 | 5.8 42.4 285 13 6 9.3 5.1
10500 5.2 41.4 290 13 7 9.5 5.2 | 6.5 43.7 290 12 6 9.5 5.2
10250 6.0 42.8 295 13 7 10.5 5.8 | 7.2 45.0 290 12 6 10.1 5.5
10000 6.8 44.2 295 13 7 10.7 5.9 | 8.0 46.4 290 12 6 10.1 5.5
9750 7.6 45.7 295 13 7 10.3 5.6 | 8.7 47.7 290 12 6 9.8 5.4
9500 8.4 47.1 295 13 6 10.5 5.7 | 9.5 49.1 295 12 6 9.6 5.3
9250 9.1 48.4 295 12 6 9.9 5.5 | 10.2 50.4 295 11 6 10.6 5.8
9000 9.9 49.8 300 12 6 9.8 5.4 | 11.0 51.8 295 11 6 10.5 5.7
8750 10.6 51.1 300 12 6 10.3 5.7 | 11.7 53.1 295 11 6 9.5 5.2
8500 11.4 52.5 300 12 6 9.7 5.3 | 12.5 54.5 300 11 5 9.4 5.2
8250 12.1 53.8 300 11 6 11.7 6.4 | 13.2 55.8 300 10 5 10.7 5.9
8000 15.1 59.2 305 10 5 27.4 15.0 | 14.1 57.4 300 10 5 14.6 8.0
7750 16.8 62.2 310 9 5 16.0 8.8 | 15.3 59.5 305 9 5 16.9 9.3
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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