Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
966
UXUS97 KBOU 141223
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0622 MDT Tuesday, October 14, 2025
This forecast is for Tuesday, October 14, 2025:
If the trigger temperature of 66.7 F/19.3 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 517 ft/min (2.6 m/s)
Maximum height of thermals.................. 12418 ft MSL (7099 ft AGL)
Forecast maximum temperature................... 75.0 F/24.3 C
Time of trigger temperature.................... 1145 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................. 10085 ft MSL (4766 ft AGL)
Thermal soaring outlook for Wednesday 10/15.... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 40700 ft MSL (35381 ft AGL)
Wave soaring outlook for Wednesday 10/15....... Poor
Remarks...
Sunrise/Sunset.................... 07:09:21 / 18:21:20 MDT
Total possible sunshine........... 11 hr 12 min 0 sec (672 min 0 sec)
Altitude of sun at 12:45:20 MDT... 41.66 degrees
Upper air data from numerical model forecast valid on 10/14/2025 at 0600 MDT
Freezing level.................. 14077 ft MSL (8758 ft AGL)
Convective condensation level... 13436 ft MSL (8117 ft AGL)
Lifted condensation level....... 12931 ft MSL (7613 ft AGL)
Lifted index.................... +0.6
K index......................... +24.2
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 -66.5 -87.7 225 66 34 2.6 1.4 M M M M M
45000 -61.5 -78.7 230 95 49 6.0 3.3 M M M M M
40000 -52.0 -61.6 225 101 52 6.8 3.7 M M M M M
38000 -48.0 -54.4 225 101 52 6.7 3.7 M M M M M
36000 -43.9 -47.0 225 101 52 6.8 3.7 M M M M M
34000 -39.5 -39.1 225 99 51 7.6 4.2 M M M M M
32000 -35.0 -31.0 225 96 49 7.6 4.2 M M M M M
30000 -30.6 -23.1 230 84 43 6.0 3.3 46.1 115.1 16.9 M M
29000 -28.8 -19.8 230 78 40 6.0 3.3 44.7 112.4 16.0 M M
28000 -27.0 -16.6 230 71 37 6.0 3.3 43.4 110.1 15.1 M M
27000 -25.1 -13.2 230 63 33 6.6 3.6 42.0 107.7 14.2 M M
26000 -23.2 -9.8 230 55 28 6.6 3.6 40.8 105.4 13.4 M M
25000 -21.2 -6.2 225 47 24 6.6 3.6 39.7 103.4 12.6 M M
24000 -19.3 -2.7 225 43 22 6.6 3.6 38.5 101.3 11.8 M M
23000 -17.3 0.9 225 43 22 6.7 3.6 37.3 99.2 10.9 M M
22000 -15.3 4.5 220 42 22 6.7 3.7 36.3 97.3 10.1 M M
21000 -13.4 7.9 220 42 22 6.8 3.7 35.2 95.3 9.3 M M
20000 -11.4 11.5 225 43 22 6.8 3.7 34.1 93.4 8.4 M M
19500 -10.4 13.3 225 43 22 6.8 3.7 33.6 92.5 8.0 M M
19000 -9.4 15.1 225 43 22 6.8 3.7 33.2 91.7 7.7 M M
18500 -8.4 16.9 220 43 22 6.7 3.7 32.6 90.7 7.2 M M
18000 -7.4 18.7 220 43 22 6.8 3.7 32.1 89.8 6.7 M M
17500 -6.5 20.3 220 43 22 6.8 3.7 31.6 88.9 6.3 M M
17000 -5.5 22.1 220 43 22 6.8 3.7 31.1 87.9 5.8 M M
16500 -4.5 23.9 215 43 22 6.9 3.8 30.6 87.1 5.4 M M
16000 -3.0 26.6 215 43 22 7.0 3.9 29.9 85.8 4.8 M M
15500 -2.0 28.4 220 43 22 6.2 3.4 29.5 85.0 4.4 M M
15000 -1.2 29.8 215 41 21 5.4 3.0 28.7 83.7 3.7 M M
14500 -0.5 31.1 215 39 20 5.4 2.9 28.0 82.4 3.0 M M
14000 0.2 32.4 215 37 19 5.3 2.9 27.2 81.0 2.2 M M
13500 1.0 33.8 215 36 18 5.3 2.9 26.5 79.7 1.5 M M
13000 1.7 35.1 215 34 18 5.2 2.9 25.8 78.4 0.8 M M
12500 2.4 36.3 215 33 17 5.2 2.8 25.1 77.1 0.0 M M
12000 3.2 37.8 210 32 16 6.5 3.5 24.4 76.0 -0.6 480 2.4
11500 4.1 39.4 210 31 16 6.5 3.5 23.9 75.0 -1.2 438 2.2
11000 5.0 41.0 210 30 15 6.0 3.3 23.3 74.0 -1.7 397 2.0
10500 5.8 42.4 205 28 15 6.6 3.6 22.7 72.9 -2.4 357 1.8
10250 6.3 43.3 205 27 14 3.5 1.9 22.4 72.4 -2.7 336 1.7
10000 6.4 43.5 205 27 14 2.3 1.3 21.8 71.3 -3.2 324 1.6
9750 6.7 44.1 205 25 13 4.4 2.4 21.4 70.4 -3.7 308 1.6
9500 7.0 44.6 205 23 12 4.2 2.3 20.9 69.6 -4.1 291 1.5
9250 7.3 45.1 210 22 11 2.7 1.5 20.5 68.8 -4.5 275 1.4
9000 7.5 45.5 205 19 10 1.0 0.6 19.8 67.7 -5.1 264 1.3
8750 7.6 45.7 205 18 9 1.5 0.8 19.2 66.5 -5.8 253 1.3
8500 7.7 45.9 205 16 8 1.4 0.8 18.5 65.3 -6.4 242 1.2
8250 7.8 46.0 205 15 7 1.0 0.5 17.9 64.1 -7.0 232 1.2
8000 7.8 46.0 200 13 7 0.6 0.3 17.2 62.9 -7.7 223 1.1
7750 7.9 46.2 195 12 6 0.7 0.4 16.5 61.6 -8.4 214 1.1
7500 7.9 46.2 190 11 6 0.3 0.2 15.8 60.4 -9.1 206 1.0
7250 7.9 46.2 185 10 5 -0.4 -0.2 15.0 59.0 -9.9 199 1.0
7000 7.9 46.2 185 9 5 -0.4 -0.2 14.2 57.6 -10.7 193 1.0
6750 7.8 46.0 180 8 4 -1.3 -0.7 13.4 56.2 -11.5 187 0.9
6500 7.7 45.9 175 8 4 -1.7 -0.9 12.6 54.6 -12.4 183 0.9
6250 7.6 45.7 165 7 3 -1.0 -0.5 11.7 53.1 -13.2 179 0.9
6000 7.5 45.5 150 6 3 -1.6 -0.9 10.9 51.6 -14.1 175 0.9
5750 7.4 45.3 135 5 3 0.0 0.0 10.1 50.2 -15.0 170 0.9
5500 7.6 45.7 120 4 2 5.4 3.0 9.5 49.2 -15.6 158 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
10/14/2025 at 0900 MDT | 10/14/2025 at 1200 MDT
|
CAPE... +0.3 LI... +0.2 | CAPE... 0.0 LI... +1.1
CINH... -0.4 K Index... +25.7 | CINH... 0.0 K Index... +11.8
|
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 -66.4 -87.5 225 61 31 2.2 1.2 | -66.4 -87.5 225 62 32 2.9 1.6
45000 -61.5 -78.7 225 91 47 5.7 3.1 | -60.9 -77.6 225 83 43 5.2 2.8
40000 -52.8 -63.0 225 97 50 7.4 4.0 | -53.0 -63.4 225 95 49 7.3 4.0
38000 -48.5 -55.3 225 98 50 7.2 4.0 | -48.7 -55.7 225 97 50 7.2 3.9
36000 -44.1 -47.4 220 99 51 7.3 4.0 | -44.4 -47.9 220 98 51 7.2 3.9
34000 -39.5 -39.1 220 97 50 7.9 4.4 | -39.7 -39.5 220 98 50 8.0 4.4
32000 -34.7 -30.5 220 94 49 8.0 4.4 | -34.2 -29.6 220 96 49 8.0 4.4
30000 -30.3 -22.5 225 86 44 5.9 3.2 | -30.2 -22.4 220 92 47 6.3 3.4
29000 -28.5 -19.3 225 82 42 5.9 3.3 | -28.4 -19.1 225 89 46 6.3 3.4
28000 -26.8 -16.2 225 77 40 5.9 3.2 | -26.5 -15.7 225 87 45 6.1 3.4
27000 -25.1 -13.2 225 67 35 5.4 3.0 | -25.0 -13.0 225 79 41 4.8 2.6
26000 -23.5 -10.3 220 56 29 5.4 3.0 | -23.5 -10.3 220 71 36 4.8 2.6
25000 -21.9 -7.4 215 45 23 5.4 3.0 | -22.1 -7.8 220 62 32 4.8 2.6
24000 -20.0 -4.0 215 39 20 7.1 3.9 | -20.2 -4.4 220 55 28 7.1 3.9
23000 -17.9 -0.2 220 37 19 7.1 3.9 | -18.1 -0.6 220 50 26 7.1 3.9
22000 -15.8 3.6 225 36 18 7.3 4.0 | -16.0 3.2 220 44 23 7.1 3.9
21000 -13.9 7.0 230 35 18 6.5 3.6 | -13.8 7.2 220 40 21 7.3 4.0
20000 -12.0 10.4 230 34 18 6.5 3.6 | -11.6 11.1 220 38 20 7.3 4.0
19500 -11.0 12.2 230 34 17 6.6 3.6 | -10.5 13.1 220 37 19 7.3 4.0
19000 -10.0 14.0 235 34 17 6.9 3.8 | -9.4 15.1 225 36 19 7.1 3.9
18500 -9.0 15.8 230 33 17 7.4 4.1 | -8.4 16.9 225 36 18 7.0 3.8
18000 -7.9 17.8 230 32 16 7.5 4.1 | -7.4 18.7 225 36 18 6.8 3.7
17500 -6.8 19.8 225 31 16 7.3 4.0 | -6.3 20.7 225 36 18 8.3 4.5
17000 -5.7 21.7 225 30 16 7.3 4.0 | -5.1 22.8 225 36 18 8.2 4.5
16500 -4.7 23.5 225 30 15 6.9 3.8 | -3.3 26.1 220 35 18 7.0 3.8
16000 -3.4 25.9 230 30 15 6.3 3.4 | -2.3 27.9 220 34 17 7.2 3.9
15500 -2.5 27.5 230 30 15 6.7 3.7 | -1.3 29.7 215 32 17 6.2 3.4
15000 -1.5 29.3 230 29 15 6.9 3.8 | -0.5 31.1 215 31 16 6.0 3.3
14500 -0.5 31.1 230 29 15 7.1 3.9 | 0.4 32.7 210 29 15 6.0 3.3
14000 0.6 33.1 230 29 15 7.5 4.1 | 1.1 34.0 210 26 13 5.8 3.2
13500 1.7 35.1 230 29 15 7.5 4.1 | 1.9 35.4 210 23 12 6.3 3.5
13000 2.9 37.2 230 29 15 7.9 4.3 | 3.0 37.4 215 21 11 8.6 4.7
12500 4.0 39.2 230 29 15 8.0 4.4 | 4.2 39.6 220 19 10 8.5 4.7
12000 5.0 41.0 235 31 16 6.2 3.4 | 5.4 41.7 230 18 9 7.7 4.2
11500 5.9 42.6 235 33 17 6.6 3.6 | 6.4 43.5 235 17 9 7.9 4.3
11000 6.7 44.1 240 35 18 3.9 2.1 | 7.4 45.3 245 16 8 5.5 3.0
10500 7.2 45.0 235 34 18 4.7 2.6 | 8.2 46.8 250 16 8 6.0 3.3
10250 7.5 45.5 235 34 17 1.9 1.0 | 8.5 47.3 250 15 8 2.7 1.5
10000 7.6 45.7 235 33 17 3.0 1.6 | 8.6 47.5 250 14 7 2.4 1.3
9750 8.0 46.4 235 31 16 6.5 3.6 | 8.9 48.0 250 12 6 4.8 2.6
9500 8.4 47.1 235 30 15 5.8 3.2 | 9.2 48.6 250 11 6 4.2 2.3
9250 8.7 47.7 230 28 14 2.8 1.5 | 9.5 49.1 250 9 5 3.6 2.0
9000 8.7 47.7 230 26 14 0.5 0.2 | 9.7 49.5 250 9 4 3.0 1.7
8750 8.8 47.8 225 25 13 1.8 1.0 | 9.9 49.8 250 8 4 3.3 1.8
8500 9.0 48.2 225 23 12 1.3 0.7 | 10.1 50.2 245 7 4 3.0 1.7
8250 9.0 48.2 225 21 11 -0.1 -0.1 | 10.3 50.5 240 7 4 2.4 1.3
8000 9.0 48.2 220 18 9 -1.0 -0.5 | 10.5 50.9 240 7 3 1.9 1.0
7750 8.9 48.0 220 16 8 -1.1 -0.6 | 10.6 51.1 235 6 3 1.2 0.7
7500 8.8 47.8 220 13 7 -2.3 -1.3 | 10.6 51.1 230 5 3 1.0 0.5
7250 8.6 47.5 220 11 6 -3.5 -1.9 | 10.7 51.3 220 4 2 1.2 0.7
7000 8.3 46.9 220 9 5 -3.0 -1.7 | 10.8 51.4 205 2 1 1.0 0.6
6750 8.0 46.4 230 7 4 -6.5 -3.5 | 10.9 51.6 160 2 1 0.8 0.4
6500 7.6 45.7 235 6 3 -1.9 -1.0 | 11.0 51.8 090 2 1 6.4 3.5
6250 7.8 46.0 230 5 2 4.7 2.6 | 11.8 53.2 075 2 1 11.1 6.1
6000 8.0 46.4 220 4 2 2.5 1.4 | 12.5 54.5 055 2 1 8.6 4.7
5750 8.3 46.9 210 3 1 4.9 2.7 | 13.2 55.8 045 2 1 12.9 7.1
5500 8.8 47.8 195 2 1 10.5 5.7 | 14.6 58.3 040 2 1 24.2 13.3
10/14/2025 at 1500 MDT | 10/14/2025 at 1800 MDT
|
CAPE... +18.1 LI... -0.4 | CAPE... +37.4 LI... -0.6
CINH... -71.0 K Index... +1.6 | CINH... -48.2 K Index... +4.3
|
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 -67.1 -88.8 220 54 28 4.2 2.3 | -68.4 -91.1 220 49 25 5.3 2.9
45000 -60.2 -76.4 225 78 40 4.8 2.6 | -60.2 -76.4 225 76 39 5.1 2.8
40000 -52.7 -62.9 225 94 48 7.3 4.0 | -52.4 -62.3 225 92 47 7.0 3.8
38000 -48.4 -55.1 225 95 49 7.2 3.9 | -48.2 -54.8 225 92 47 6.9 3.8
36000 -44.1 -47.4 225 96 49 7.2 3.9 | -44.1 -47.4 225 92 47 6.9 3.8
34000 -39.4 -38.9 225 95 49 8.1 4.5 | -39.5 -39.1 225 91 47 7.9 4.4
32000 -33.9 -29.0 220 94 49 8.1 4.4 | -34.1 -29.4 225 91 47 7.9 4.3
30000 -29.8 -21.6 220 91 47 6.4 3.5 | -30.3 -22.5 225 83 43 6.0 3.3
29000 -27.9 -18.2 220 89 46 6.4 3.5 | -28.4 -19.1 225 78 40 6.0 3.3
28000 -26.0 -14.8 225 86 44 6.2 3.4 | -26.6 -15.9 225 74 38 6.0 3.3
27000 -24.5 -12.1 225 80 41 4.8 2.6 | -24.9 -12.8 230 67 35 5.9 3.2
26000 -23.0 -9.4 225 73 37 4.8 2.6 | -23.1 -9.6 230 61 31 5.9 3.2
25000 -21.6 -6.9 225 65 34 4.7 2.6 | -21.4 -6.5 230 54 28 5.8 3.2
24000 -19.8 -3.6 220 58 30 6.9 3.8 | -19.4 -2.9 230 51 26 6.8 3.7
23000 -17.7 0.1 220 51 26 6.9 3.8 | -17.4 0.7 230 49 25 6.8 3.8
22000 -15.7 3.7 220 43 22 6.9 3.8 | -15.3 4.5 230 48 25 6.8 3.8
21000 -13.5 7.7 220 41 21 7.1 3.9 | -13.3 8.1 230 45 23 7.0 3.8
20000 -11.4 11.5 225 42 21 7.1 3.9 | -11.2 11.8 230 43 22 7.0 3.8
19500 -10.4 13.3 225 42 22 7.1 3.9 | -10.1 13.8 230 41 21 7.0 3.9
19000 -9.3 15.3 225 42 22 7.2 3.9 | -9.1 15.6 230 40 21 7.5 4.1
18500 -8.2 17.2 225 42 22 7.2 4.0 | -7.9 17.8 230 39 20 7.9 4.3
18000 -7.1 19.2 225 42 22 7.2 3.9 | -6.7 19.9 225 37 19 8.0 4.4
17500 -6.0 21.2 225 42 22 8.3 4.6 | -5.5 22.1 225 36 18 7.9 4.3
17000 -4.1 24.6 225 42 22 8.3 4.5 | -4.4 24.1 225 34 18 7.9 4.3
16500 -2.9 26.8 225 42 21 7.6 4.2 | -2.6 27.3 225 32 17 7.4 4.0
16000 -1.8 28.8 225 41 21 7.7 4.2 | -1.5 29.3 230 32 16 7.5 4.1
15500 -0.6 30.9 225 41 21 7.4 4.1 | -0.5 31.1 230 31 16 4.9 2.7
15000 0.5 32.9 225 40 20 7.3 4.0 | 0.1 32.2 230 30 16 4.3 2.4
14500 1.6 34.9 225 39 20 6.5 3.6 | 0.6 33.1 230 30 15 4.0 2.2
14000 2.3 36.1 225 36 18 5.3 2.9 | 1.1 34.0 225 28 15 3.8 2.1
13500 3.1 37.6 225 32 17 5.4 3.0 | 1.5 34.7 220 27 14 4.8 2.6
13000 3.7 38.7 220 29 15 4.9 2.7 | 2.2 36.0 215 27 14 7.2 3.9
12500 4.3 39.7 215 26 13 5.3 2.9 | 3.1 37.6 205 26 13 7.4 4.0
12000 5.1 41.2 210 25 13 7.7 4.2 | 4.4 39.9 205 25 13 9.3 5.1
11500 6.2 43.2 210 25 13 7.8 4.3 | 5.8 42.4 200 25 13 9.2 5.0
11000 7.0 44.6 205 23 12 5.7 3.1 | 7.2 45.0 200 24 12 9.7 5.3
10500 7.7 45.9 205 20 11 5.9 3.2 | 8.6 47.5 200 23 12 8.0 4.4
10250 8.0 46.4 200 19 10 4.8 2.7 | 9.1 48.4 195 23 12 4.7 2.6
10000 8.4 47.1 200 19 10 6.9 3.8 | 9.5 49.1 195 21 11 7.8 4.3
9750 9.1 48.4 195 18 9 9.0 4.9 | 10.2 50.4 190 19 10 10.3 5.7
9500 9.7 49.5 190 17 9 8.4 4.6 | 10.9 51.6 185 18 9 9.5 5.2
9250 10.3 50.5 185 16 8 8.3 4.5 | 11.5 52.7 180 16 8 7.9 4.3
9000 10.9 51.6 175 15 8 7.1 3.9 | 12.0 53.6 175 14 7 6.7 3.7
8750 11.3 52.3 170 14 7 6.6 3.6 | 12.5 54.5 170 12 6 7.1 3.9
8500 11.8 53.2 165 13 7 6.3 3.4 | 12.9 55.2 160 10 5 6.5 3.6
8250 12.2 54.0 150 11 6 4.2 2.3 | 13.3 55.9 145 9 5 5.0 2.8
8000 12.5 54.5 135 9 5 3.4 1.8 | 13.6 56.5 130 7 4 4.9 2.7
7750 12.7 54.9 120 8 4 2.8 1.5 | 14.0 57.2 115 6 3 5.6 3.1
7500 12.9 55.2 095 7 4 5.2 2.9 | 14.4 57.9 095 6 3 5.9 3.3
7250 13.5 56.3 085 7 3 8.9 4.9 | 14.8 58.6 075 5 3 6.3 3.4
7000 14.2 57.6 080 6 3 9.1 5.0 | 15.3 59.5 050 6 3 6.2 3.4
6750 14.8 58.6 070 6 3 9.4 5.2 | 15.7 60.3 035 7 3 5.8 3.2
6500 15.5 59.9 065 6 3 10.2 5.6 | 16.2 61.2 025 7 4 7.1 3.9
6250 16.3 61.3 065 6 3 10.8 5.9 | 16.8 62.2 015 8 4 8.2 4.5
6000 17.1 62.8 060 6 3 9.7 5.3 | 17.3 63.1 010 9 4 8.0 4.4
5750 17.9 64.2 055 6 3 12.2 6.7 | 17.9 64.2 360 9 5 7.5 4.1
5500 19.1 66.4 055 5 3 20.8 11.4 | 18.4 65.1 355 8 4 6.1 3.4
________________________________________________________________________________
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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