Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
304
UXUS97 KBOU 071213
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0612 MDT Saturday, June 7, 2025
This forecast is for Saturday, June 7, 2025:
If the trigger temperature of 71.2 F/21.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 903 ft/min (4.6 m/s)
Maximum height of thermals.................. 15825 ft MSL (10489 ft AGL)
Forecast maximum temperature................... 81.0 F/27.7 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 13887 ft MSL (8551 ft AGL)
Thermal soaring outlook for Sunday 06/08....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change. Lapse rates unstable
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 25061 ft MSL (19725 ft AGL)
Wave soaring outlook for Sunday 06/08.......... Poor
Remarks...
Sunrise/Sunset.................... 05:31:24 / 20:25:33 MDT
Total possible sunshine........... 14 hr 54 min 9 sec (894 min 9 sec)
Altitude of sun at 12:58:29 MDT... 73.06 degrees
Upper air data from numerical model forecast valid on 06/07/2025 at 0600 MDT
Freezing level.................. 13054 ft MSL (7718 ft AGL)
Convective condensation level... 17102 ft MSL (11766 ft AGL)
Lifted condensation level....... 16491 ft MSL (11155 ft AGL)
Lifted index.................... +0.5
K index......................... -2.7
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 -59.5 -75.1 265 49 25 1.3 0.7 M M M M M
45000 -57.6 -71.7 270 56 29 1.0 0.5 M M M M M
40000 -56.2 -69.2 275 67 34 0.8 0.4 M M M M M
38000 -53.5 -64.3 275 51 26 4.2 2.3 M M M M M
36000 -51.0 -59.8 275 36 18 4.2 2.3 M M M M M
34000 -46.9 -52.4 275 29 15 8.3 4.6 M M M M M
32000 -41.9 -43.4 280 27 14 8.3 4.6 M M M M M
30000 -36.7 -34.1 285 27 14 8.7 4.8 38.7 101.7 8.7 M M
29000 -34.1 -29.4 290 28 14 8.7 4.8 38.3 101.0 8.5 M M
28000 -31.5 -24.7 290 29 15 8.7 4.8 38.0 100.4 8.4 M M
27000 -28.9 -20.0 290 29 15 8.6 4.7 37.5 99.6 8.1 M M
26000 -26.4 -15.5 290 29 15 8.6 4.7 37.0 98.7 7.8 M M
25000 -23.8 -10.8 290 29 15 8.5 4.7 36.6 98.0 7.6 M M
24000 -21.4 -6.5 295 29 15 7.6 4.2 36.1 96.9 7.2 M M
23000 -19.1 -2.4 300 29 15 7.7 4.2 35.2 95.4 6.6 M M
22000 -16.8 1.8 300 29 15 7.7 4.2 34.5 94.2 6.0 M M
21000 -14.6 5.7 305 29 15 7.2 4.0 33.7 92.7 5.4 M M
20000 -11.9 10.6 310 28 15 7.2 3.9 32.5 90.6 4.5 M M
19500 -10.8 12.6 310 28 15 7.2 4.0 32.1 89.8 4.2 M M
19000 -9.7 14.5 315 28 14 6.7 3.7 31.7 89.1 3.8 M M
18500 -8.7 16.3 315 28 14 6.6 3.6 31.1 88.1 3.4 M M
18000 -7.7 18.1 315 28 14 6.5 3.5 30.6 87.1 2.9 M M
17500 -6.8 19.8 320 27 14 5.5 3.0 29.9 85.9 2.3 M M
17000 -6.0 21.2 320 26 14 5.6 3.1 29.2 84.6 1.7 M M
16500 -5.2 22.6 320 26 13 4.4 2.4 28.4 83.2 1.0 M M
16000 -4.6 23.7 320 24 13 4.3 2.4 27.5 81.5 0.2 M M
15500 -4.0 24.8 320 23 12 4.4 2.4 26.6 79.9 -0.6 877 4.5
15000 -3.3 26.1 320 22 11 4.5 2.5 25.7 78.3 -1.5 843 4.3
14500 -2.7 27.1 320 21 11 4.8 2.7 24.9 76.8 -2.3 808 4.1
14000 -1.8 28.8 320 20 10 6.5 3.6 24.2 75.6 -2.9 768 3.9
13500 -0.9 30.4 325 19 10 6.4 3.5 23.7 74.6 -3.5 725 3.7
13000 0.2 32.4 325 19 10 8.3 4.6 23.3 73.9 -3.9 679 3.4
12500 1.3 34.3 330 18 9 8.1 4.5 23.0 73.5 -4.2 629 3.2
12000 2.6 36.7 330 17 9 9.0 4.9 22.8 73.1 -4.5 577 2.9
11500 3.9 39.0 330 17 9 9.0 4.9 22.7 72.9 -4.7 524 2.7
11000 5.2 41.4 330 16 8 9.7 5.3 22.6 72.8 -4.8 469 2.4
10500 6.6 43.9 330 17 9 11.0 6.0 22.6 72.7 -4.9 411 2.1
10250 7.3 45.1 330 17 9 4.5 2.5 22.6 72.7 -4.9 383 1.9
10000 7.5 45.5 330 16 8 5.9 3.2 22.0 71.6 -5.5 371 1.9
9750 8.3 46.9 325 17 9 13.1 7.2 22.1 71.9 -5.4 338 1.7
9500 9.2 48.6 320 17 9 12.0 6.6 22.3 72.2 -5.3 305 1.6
9250 10.0 50.0 320 18 9 8.4 4.6 22.4 72.4 -5.2 273 1.4
9000 10.4 50.7 320 18 9 6.6 3.6 22.1 71.9 -5.5 252 1.3
8750 11.1 52.0 320 18 9 9.4 5.2 22.1 71.7 -5.6 226 1.1
8500 11.7 53.1 315 18 9 8.6 4.7 22.0 71.6 -5.7 199 1.0
8250 12.4 54.3 310 19 10 8.7 4.7 21.9 71.4 -5.9 173 0.9
8000 13.0 55.4 310 20 10 8.0 4.4 21.8 71.3 -6.0 147 0.7
7750 13.5 56.3 305 20 10 7.2 4.0 21.6 70.9 -6.2 124 0.6
7500 14.0 57.2 305 20 10 6.1 3.4 21.4 70.5 -6.5 102 0.5
7250 14.4 57.9 300 20 10 5.0 2.7 21.1 69.9 -6.8 83 0.4
7000 14.7 58.5 300 21 11 4.4 2.4 20.7 69.2 -7.2 65 0.3
6750 15.0 59.0 295 20 11 6.0 3.3 20.3 68.6 -7.6 48 0.2
6500 15.4 59.7 290 18 9 0.9 0.5 19.9 67.9 -8.1 31 0.2
6250 15.1 59.2 285 15 8 -4.8 -2.7 19.0 66.1 -9.1 32 0.2
6000 14.8 58.6 275 12 6 -1.2 -0.7 18.0 64.3 -10.2 33 0.2
5750 14.6 58.3 260 9 5 -7.6 -4.2 17.0 62.7 -11.2 33 0.2
5500 13.0 55.4 245 8 4 -34.0 -18.7 14.9 58.7 -13.4 71 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/07/2025 at 0900 MDT | 06/07/2025 at 1200 MDT
|
CAPE... +20.6 LI... +2.3 | CAPE... +18.0 LI... +1.2
CINH... -70.4 K Index... +5.4 | CINH... -15.5 K Index... +0.2
|
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 -59.4 -74.9 270 47 24 1.6 0.9 | -59.9 -75.8 275 47 24 2.0 1.1
45000 -57.2 -71.0 270 54 28 0.5 0.3 | -57.3 -71.1 275 52 27 0.4 0.2
40000 -56.4 -69.5 275 55 29 2.1 1.1 | -56.7 -70.1 270 49 25 0.3 0.2
38000 -53.7 -64.7 275 48 25 4.6 2.5 | -54.1 -65.4 270 44 23 4.8 2.6
36000 -50.9 -59.6 270 40 21 4.6 2.5 | -50.8 -59.4 275 39 20 4.8 2.6
34000 -47.0 -52.6 270 35 18 7.9 4.3 | -46.8 -52.2 280 37 19 7.9 4.3
32000 -42.3 -44.1 270 31 16 7.9 4.3 | -42.0 -43.6 280 36 18 7.9 4.3
30000 -36.6 -33.9 270 30 15 8.7 4.7 | -37.1 -34.8 280 35 18 8.5 4.7
29000 -34.1 -29.4 275 30 15 8.7 4.7 | -34.5 -30.1 280 34 18 8.5 4.7
28000 -31.5 -24.7 275 30 16 8.7 4.8 | -32.0 -25.6 280 34 18 8.5 4.7
27000 -28.9 -20.0 275 31 16 8.4 4.6 | -29.5 -21.1 280 34 18 8.1 4.5
26000 -26.4 -15.5 275 31 16 8.4 4.6 | -27.1 -16.8 285 34 18 8.1 4.5
25000 -23.9 -11.0 275 32 16 8.4 4.6 | -24.6 -12.3 285 35 18 8.1 4.5
24000 -21.5 -6.7 280 31 16 7.7 4.2 | -22.3 -8.1 290 35 18 7.7 4.2
23000 -19.2 -2.6 280 31 16 7.7 4.2 | -20.0 -4.0 290 35 18 7.7 4.2
22000 -17.0 1.4 285 30 15 7.7 4.2 | -17.7 0.1 290 35 18 7.7 4.2
21000 -14.8 5.4 285 29 15 7.0 3.8 | -15.4 4.3 290 34 18 7.4 4.1
20000 -12.7 9.1 290 29 15 7.0 3.8 | -13.2 8.2 290 34 18 7.4 4.1
19500 -11.7 10.9 290 29 15 6.9 3.8 | -12.1 10.2 290 34 17 7.4 4.1
19000 -10.7 12.7 290 28 15 6.7 3.7 | -10.4 13.3 290 33 17 7.0 3.9
18500 -9.7 14.5 290 28 14 6.2 3.4 | -9.4 15.1 285 33 17 7.0 3.9
18000 -8.8 16.2 295 27 14 6.2 3.4 | -8.3 17.1 285 32 16 7.1 3.9
17500 -7.9 17.8 295 26 13 6.0 3.3 | -7.3 18.9 285 31 16 7.3 4.0
17000 -7.0 19.4 295 25 13 6.0 3.3 | -6.2 20.8 285 30 15 7.2 3.9
16500 -5.7 21.7 295 23 12 5.7 3.2 | -5.1 22.8 285 29 15 7.8 4.3
16000 -4.9 23.2 295 22 11 5.8 3.2 | -3.9 25.0 285 27 14 7.8 4.3
15500 -4.0 24.8 300 20 10 6.0 3.3 | -2.7 27.1 285 26 13 7.7 4.2
15000 -3.1 26.4 300 18 9 6.2 3.4 | -1.6 29.1 290 24 13 7.6 4.2
14500 -2.2 28.0 300 17 9 6.7 3.7 | -0.4 31.3 290 23 12 7.3 4.0
14000 -1.1 30.0 305 15 8 7.8 4.3 | 0.6 33.1 295 22 11 6.6 3.6
13500 0.0 32.0 305 14 7 7.8 4.3 | 1.5 34.7 295 20 10 6.6 3.6
13000 1.2 34.2 310 13 7 8.3 4.6 | 2.5 36.5 300 19 10 6.6 3.6
12500 2.4 36.3 310 13 7 8.3 4.6 | 3.5 38.3 305 18 9 6.7 3.7
12000 3.7 38.7 310 13 7 8.8 4.8 | 4.4 39.9 305 17 9 6.5 3.6
11500 5.0 41.0 315 13 7 8.8 4.8 | 5.3 41.5 310 16 8 6.5 3.6
11000 6.2 43.2 310 13 7 8.1 4.4 | 6.4 43.5 310 15 8 8.3 4.5
10500 7.4 45.3 310 14 7 7.5 4.1 | 7.5 45.5 310 14 7 7.2 3.9
10250 7.8 46.0 305 14 7 4.8 2.6 | 7.9 46.2 310 13 7 3.7 2.0
10000 8.2 46.8 305 14 7 7.1 3.9 | 8.3 46.9 310 13 7 7.9 4.3
9750 8.8 47.8 305 14 7 9.9 5.4 | 9.1 48.4 310 13 7 12.2 6.7
9500 9.5 49.1 305 15 8 9.1 5.0 | 9.9 49.8 310 13 7 11.0 6.0
9250 10.1 50.2 305 15 8 6.7 3.7 | 10.6 51.1 310 13 7 7.7 4.2
9000 10.5 50.9 305 15 8 6.8 3.7 | 11.1 52.0 310 12 6 8.2 4.5
8750 11.1 52.0 305 15 8 8.9 4.9 | 11.8 53.2 310 12 6 11.3 6.2
8500 11.7 53.1 305 15 8 8.0 4.4 | 12.6 54.7 310 12 6 10.1 5.6
8250 12.3 54.1 305 15 8 7.1 3.9 | 13.3 55.9 305 11 6 8.7 4.8
8000 12.8 55.0 305 15 8 6.7 3.7 | 13.9 57.0 310 10 5 9.0 4.9
7750 13.3 55.9 305 15 8 7.8 4.3 | 14.6 58.3 305 10 5 11.0 6.1
7500 13.8 56.8 305 16 8 6.3 3.5 | 15.4 59.7 305 10 5 10.0 5.5
7250 14.1 57.4 305 15 8 4.2 2.3 | 16.1 61.0 305 10 5 8.2 4.5
7000 14.4 57.9 300 14 7 4.5 2.5 | 16.7 62.1 305 9 5 8.7 4.8
6750 14.8 58.6 295 14 7 7.7 4.2 | 17.4 63.3 305 9 5 12.1 6.6
6500 15.4 59.7 295 13 7 8.7 4.8 | 18.4 65.1 305 9 5 12.0 6.6
6250 16.0 60.8 290 10 5 7.6 4.2 | 19.2 66.6 305 9 4 10.3 5.7
6000 16.5 61.7 285 8 4 7.3 4.0 | 20.8 69.4 305 8 4 9.6 5.2
5750 17.0 62.6 275 6 3 9.3 5.1 | 20.7 69.3 305 8 4 13.7 7.5
5500 17.8 64.0 275 5 3 16.0 8.8 | 22.2 72.0 305 8 4 27.0 14.8
06/07/2025 at 1500 MDT | 06/07/2025 at 1800 MDT
|
CAPE... +194.3 LI... -0.2 | CAPE... +180.1 LI... -0.8
CINH... -41.8 K Index... +11.8 | CINH... -22.8 K Index... +19.9
|
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 -60.2 -76.4 275 43 22 1.4 0.8 | -60.5 -76.9 275 42 22 1.1 0.6
45000 -58.1 -72.6 275 46 23 1.6 0.9 | -58.8 -73.8 280 44 23 1.6 0.9
40000 -55.6 -68.1 280 49 25 2.9 1.6 | -56.2 -69.2 300 38 20 3.7 2.0
38000 -53.0 -63.4 285 48 25 4.3 2.4 | -53.2 -63.8 310 31 16 5.0 2.7
36000 -50.5 -58.9 285 47 24 4.3 2.3 | -50.2 -58.4 330 26 13 5.0 2.7
34000 -46.6 -51.9 285 45 23 7.8 4.3 | -46.1 -51.0 345 25 13 7.9 4.3
32000 -41.9 -43.4 285 43 22 7.8 4.3 | -41.4 -42.5 350 26 13 7.9 4.3
30000 -36.7 -34.1 290 39 20 7.8 4.3 | -36.1 -33.0 340 25 13 7.8 4.3
29000 -34.4 -29.9 290 37 19 7.8 4.3 | -33.7 -28.7 325 25 13 7.8 4.3
28000 -32.1 -25.8 290 36 18 7.8 4.3 | -31.4 -24.5 320 27 14 7.8 4.3
27000 -29.8 -21.6 295 34 17 7.9 4.3 | -29.0 -20.2 315 26 13 7.8 4.3
26000 -27.4 -17.3 295 33 17 7.9 4.3 | -26.7 -16.1 310 25 13 7.8 4.3
25000 -25.1 -13.2 300 31 16 7.9 4.4 | -24.4 -11.9 305 25 13 7.8 4.3
24000 -22.8 -9.0 300 31 16 7.7 4.2 | -22.1 -7.8 300 24 12 7.4 4.1
23000 -20.5 -4.9 300 32 16 7.7 4.2 | -19.9 -3.8 300 23 12 7.5 4.1
22000 -18.2 -0.8 300 32 17 7.7 4.2 | -17.7 0.1 300 23 12 7.5 4.1
21000 -15.9 3.4 300 33 17 8.0 4.4 | -15.5 4.1 300 22 12 7.5 4.1
20000 -13.5 7.7 300 32 17 8.0 4.4 | -13.4 7.9 300 22 12 7.5 4.1
19500 -12.3 9.9 300 32 17 8.0 4.4 | -12.3 9.9 300 22 12 7.5 4.1
19000 -11.1 12.0 295 32 17 8.1 4.4 | -11.2 11.8 300 23 12 7.6 4.2
18500 -9.8 14.4 295 31 16 8.1 4.5 | -10.0 14.0 300 23 12 7.7 4.2
18000 -8.6 16.5 295 31 16 8.1 4.5 | -8.9 16.0 300 23 12 7.7 4.2
17500 -7.4 18.7 295 30 15 8.0 4.4 | -7.7 18.1 300 24 12 8.1 4.5
17000 -6.2 20.8 295 29 15 8.0 4.4 | -5.9 21.4 300 25 13 8.1 4.5
16500 -5.0 23.0 290 28 14 7.7 4.2 | -4.7 23.5 300 25 13 8.5 4.7
16000 -3.3 26.1 290 27 14 7.6 4.2 | -3.5 25.7 295 25 13 8.5 4.6
15500 -2.2 28.0 295 26 14 7.7 4.2 | -2.2 28.0 295 25 13 8.8 4.8
15000 -1.1 30.0 295 26 14 7.7 4.2 | -0.9 30.4 295 25 13 8.9 4.9
14500 0.0 32.0 295 26 14 7.8 4.3 | 0.4 32.7 295 25 13 8.9 4.9
14000 1.2 34.2 295 25 13 7.9 4.4 | 1.7 35.1 300 25 13 8.9 4.9
13500 2.3 36.1 295 25 13 8.0 4.4 | 3.0 37.4 300 24 12 9.0 4.9
13000 3.5 38.3 295 23 12 8.2 4.5 | 4.3 39.7 300 23 12 9.1 5.0
12500 4.6 40.3 295 22 11 8.3 4.5 | 5.6 42.1 300 22 11 9.2 5.0
12000 5.8 42.4 295 20 10 8.2 4.5 | 7.0 44.6 305 21 11 9.3 5.1
11500 6.9 44.4 300 18 9 8.2 4.5 | 8.4 47.1 305 20 10 9.3 5.1
11000 8.2 46.8 300 16 8 8.8 4.8 | 9.7 49.5 305 19 10 8.9 4.9
10500 9.5 49.1 300 15 8 4.6 2.5 | 11.1 52.0 310 17 9 4.6 2.5
10250 9.7 49.5 300 15 8 6.2 3.4 | 11.3 52.3 310 17 9 5.9 3.2
10000 10.6 51.1 300 14 7 12.9 7.1 | 12.1 53.8 310 16 8 12.6 6.9
9750 11.4 52.5 300 14 7 11.2 6.1 | 12.9 55.2 310 15 8 10.9 6.0
9500 12.2 54.0 300 13 7 11.3 6.2 | 13.8 56.8 310 14 7 11.0 6.0
9250 13.0 55.4 300 13 7 9.0 4.9 | 14.5 58.1 310 13 7 9.2 5.1
9000 13.6 56.5 300 13 7 9.4 5.2 | 15.2 59.4 310 13 7 9.5 5.2
8750 14.4 57.9 300 13 7 11.0 6.1 | 15.9 60.6 315 13 7 10.5 5.8
8500 15.2 59.4 300 12 6 10.4 5.7 | 16.7 62.1 315 12 6 10.1 5.6
8250 16.0 60.8 300 12 6 9.8 5.4 | 17.4 63.3 315 12 6 9.7 5.3
8000 16.7 62.1 300 13 7 9.8 5.4 | 18.2 64.8 315 12 6 9.7 5.3
7750 17.4 63.3 300 12 6 10.5 5.8 | 18.9 66.0 315 12 6 10.0 5.5
7500 18.2 64.8 300 11 6 9.8 5.4 | 19.6 67.3 315 11 6 9.6 5.2
7250 18.9 66.0 300 11 6 8.5 4.7 | 20.3 68.5 315 11 6 8.7 4.8
7000 19.5 67.1 300 12 6 9.0 4.9 | 21.0 69.8 315 11 6 9.2 5.0
6750 20.3 68.5 305 12 6 11.6 6.4 | 21.7 71.1 315 11 6 11.4 6.3
6500 21.2 70.2 305 10 5 11.7 6.4 | 22.6 72.7 320 10 5 11.2 6.1
6250 22.0 71.6 305 10 5 10.8 6.0 | 23.3 73.9 320 10 5 10.0 5.5
6000 22.8 73.0 305 11 5 10.1 5.6 | 24.1 75.4 320 10 5 9.9 5.4
5750 23.6 74.5 305 11 5 12.8 7.0 | 24.8 76.6 320 10 5 10.3 5.7
5500 24.9 76.8 305 9 5 24.0 13.2 | 25.7 78.3 320 8 4 15.0 8.2
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC) and again by approximately 1830 MST/1930 MDT (0130 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 old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 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.
CINH (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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