Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
303
UXUS97 KBOU 160141
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1821 MST Saturday, November 15, 2025
This forecast is for Sunday, November 16, 2025:
If the trigger temperature of 68.2 F/20.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 413 ft/min (2.1 m/s)
Maximum height of thermals.................. 10649 ft MSL (5370 ft AGL)
Forecast maximum temperature................... 70.0 F/21.6 C
Time of trigger temperature.................... 1245 MST
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................. 7642 ft MSL (2362 ft AGL)
Thermal soaring outlook for Monday 11/17....... Poor
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Weak PVA
Potential height of wave....................... 16603 ft MSL (11324 ft AGL)
Wave soaring outlook for Monday 11/17.......... Fair
Remarks...
Sunrise/Sunset.................... 06:45:55 / 16:42:43 MST
Total possible sunshine........... 9 hr 56 min 48 sec (596 min 48 sec)
Altitude of sun at 11:44:19 MST... 31.18 degrees
Upper air data from numerical model forecast valid on 11/16/2025 at 0500 MST
Freezing level.................. 12827 ft MSL (7548 ft AGL)
Convective condensation level... 17663 ft MSL (12384 ft AGL)
Lifted condensation level....... 15129 ft MSL (9850 ft AGL)
Lifted index.................... +4.8
K index......................... +10.7
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 -64.0 -83.2 260 40 21 1.4 0.8 M M M M M
45000 -61.6 -78.9 260 45 23 1.9 1.1 M M M M M
40000 -58.7 -73.7 265 52 27 1.2 0.7 M M M M M
38000 -54.7 -66.5 260 55 28 7.3 4.0 M M M M M
36000 -50.3 -58.5 260 57 29 7.3 4.0 M M M M M
34000 -45.8 -50.4 255 57 29 7.6 4.1 M M M M M
32000 -41.3 -42.3 255 55 28 7.6 4.1 M M M M M
30000 -36.1 -33.0 250 50 26 7.9 4.3 39.8 103.6 14.1 M M
29000 -33.8 -28.8 250 46 24 7.9 4.3 39.0 102.3 13.7 M M
28000 -31.4 -24.5 250 42 22 7.9 4.3 38.4 101.1 13.4 M M
27000 -29.1 -20.4 250 39 20 7.3 4.0 37.6 99.6 12.9 M M
26000 -27.0 -16.6 250 35 18 7.3 4.0 36.5 97.8 12.2 M M
25000 -24.8 -12.6 250 31 16 7.3 4.0 35.7 96.2 11.6 M M
24000 -22.6 -8.7 250 29 15 7.5 4.1 34.8 94.7 11.1 M M
23000 -20.4 -4.7 250 27 14 7.5 4.1 33.9 93.1 10.5 M M
22000 -18.2 -0.8 250 26 13 7.5 4.1 33.1 91.7 9.9 M M
21000 -16.1 3.0 250 25 13 6.4 3.5 32.2 89.9 9.2 M M
20000 -14.1 6.6 250 23 12 6.4 3.5 31.0 87.7 8.3 M M
19500 -13.1 8.4 245 22 11 6.4 3.5 30.4 86.7 7.9 M M
19000 -12.2 10.0 245 21 11 6.4 3.5 29.9 85.7 7.5 M M
18500 -11.2 11.8 245 20 10 6.5 3.6 29.3 84.7 7.0 M M
18000 -10.2 13.6 245 19 10 6.5 3.5 28.7 83.7 6.6 M M
17500 -9.3 15.3 245 18 9 6.0 3.3 28.2 82.7 6.1 M M
17000 -8.5 16.7 245 16 8 5.7 3.1 27.5 81.4 5.5 M M
16500 -7.6 18.3 250 15 8 5.7 3.1 26.8 80.2 4.9 M M
16000 -6.8 19.8 250 13 7 6.0 3.3 26.1 79.0 4.3 M M
15500 -6.0 21.2 255 12 6 6.0 3.3 25.5 77.8 3.7 M M
15000 -4.5 23.9 265 10 5 7.1 3.9 24.7 76.4 2.9 M M
14500 -3.5 25.7 275 10 5 7.1 3.9 24.2 75.6 2.5 M M
14000 -2.4 27.7 280 10 5 7.8 4.3 23.9 74.9 2.1 M M
13500 -1.3 29.7 285 10 5 7.8 4.3 23.5 74.4 1.8 M M
13000 -0.2 31.6 290 11 6 7.6 4.2 23.2 73.8 1.5 M M
12500 0.9 33.6 295 12 6 7.6 4.2 22.8 73.1 1.1 M M
12000 2.0 35.6 295 13 7 7.8 4.3 22.5 72.5 0.8 M M
11500 3.2 37.8 300 14 7 7.8 4.3 22.2 72.0 0.5 M M
11000 4.3 39.7 300 15 8 8.1 4.4 21.9 71.4 0.2 M M
10500 5.5 41.9 300 15 7 9.0 4.9 21.6 70.9 -0.1 392 2.0
10250 6.1 43.0 300 14 7 4.5 2.5 21.5 70.7 -0.2 367 1.9
10000 6.3 43.3 300 14 7 5.2 2.8 21.0 69.7 -0.8 354 1.8
9750 7.0 44.6 300 14 7 9.9 5.4 20.9 69.6 -0.8 326 1.7
9500 7.6 45.7 305 13 7 9.5 5.2 20.8 69.5 -0.9 299 1.5
9250 8.3 46.9 305 13 6 6.3 3.5 20.8 69.4 -1.0 272 1.4
9000 8.6 47.5 305 12 6 4.8 2.6 20.4 68.6 -1.4 255 1.3
8750 9.1 48.4 310 12 6 7.5 4.1 20.1 68.2 -1.6 232 1.2
8500 9.7 49.5 310 11 6 7.6 4.1 19.9 67.9 -1.8 208 1.1
8250 10.2 50.4 310 11 6 5.7 3.1 19.7 67.5 -2.0 185 0.9
8000 10.5 50.9 310 10 5 3.7 2.0 19.3 66.7 -2.4 168 0.9
7750 10.8 51.4 315 10 5 4.5 2.5 18.9 66.0 -2.8 151 0.8
7500 11.2 52.2 315 10 5 4.2 2.3 18.5 65.3 -3.2 134 0.7
7250 11.4 52.5 315 10 5 3.1 1.7 18.0 64.4 -3.7 119 0.6
7000 11.6 52.9 315 9 5 2.4 1.3 17.5 63.4 -4.2 105 0.5
6750 11.8 53.2 320 9 5 2.9 1.6 16.9 62.5 -4.8 92 0.5
6500 12.0 53.6 320 8 4 -0.2 -0.1 16.3 61.4 -5.4 80 0.4
6250 11.8 53.2 315 8 4 -3.9 -2.2 15.4 59.7 -6.3 79 0.4
6000 11.5 52.7 315 7 3 -2.8 -1.6 14.4 57.9 -7.4 79 0.4
5750 11.2 52.2 310 6 3 -6.0 -3.3 13.4 56.1 -8.4 80 0.4
5500 10.3 50.5 295 4 2 -22.0 -12.1 11.7 53.0 -10.1 102 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/16/2025 at 0800 MST | 11/16/2025 at 1100 MST
|
CAPE... 0.0 LI... +4.6 | CAPE... 0.0 LI... +3.6
CINH... -0.8 K Index... +6.3 | CINH... 0.0 K Index... +15.7
|
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 -63.8 -82.8 250 38 19 0.9 0.5 | -63.4 -82.1 250 35 18 0.3 0.2
45000 -62.2 -80.0 255 43 22 2.0 1.1 | -62.7 -80.9 250 39 20 2.6 1.5
40000 -59.2 -74.6 260 49 25 1.3 0.7 | -58.6 -73.5 240 44 23 2.1 1.1
38000 -55.2 -67.4 260 51 26 7.4 4.1 | -54.9 -66.8 240 46 23 6.8 3.7
36000 -50.7 -59.3 260 53 27 7.4 4.1 | -50.8 -59.4 240 47 24 6.8 3.7
34000 -46.0 -50.8 255 54 28 8.3 4.6 | -46.3 -51.3 240 48 25 8.4 4.6
32000 -41.1 -42.0 255 53 27 8.3 4.6 | -41.2 -42.2 245 50 26 8.4 4.6
30000 -36.0 -32.8 255 50 26 6.6 3.6 | -36.5 -33.7 245 50 26 7.3 4.0
29000 -34.1 -29.4 250 47 24 6.6 3.6 | -33.7 -28.7 245 48 25 7.3 4.0
28000 -32.1 -25.8 245 45 23 6.6 3.6 | -31.5 -24.7 240 47 24 7.3 4.0
27000 -30.0 -22.0 245 42 22 7.5 4.1 | -29.5 -21.1 240 45 23 6.5 3.6
26000 -27.8 -18.0 240 39 20 7.5 4.1 | -27.5 -17.5 235 43 22 6.5 3.6
25000 -25.5 -13.9 240 35 18 7.6 4.1 | -25.6 -14.1 235 41 21 6.5 3.6
24000 -23.3 -9.9 240 32 17 8.0 4.4 | -23.6 -10.5 235 39 20 7.9 4.4
23000 -20.9 -5.6 240 30 15 7.9 4.4 | -21.2 -6.2 235 36 19 7.8 4.3
22000 -18.5 -1.3 240 27 14 7.9 4.3 | -18.9 -2.0 235 34 18 7.8 4.3
21000 -16.4 2.5 240 25 13 6.4 3.5 | -16.7 1.9 235 32 16 6.9 3.8
20000 -14.4 6.1 240 24 12 6.5 3.5 | -14.6 5.7 235 30 15 6.9 3.8
19500 -13.5 7.7 240 23 12 6.5 3.5 | -13.6 7.5 230 29 15 7.0 3.8
19000 -12.5 9.5 240 22 11 6.4 3.5 | -12.6 9.3 230 27 14 7.1 3.9
18500 -11.5 11.3 245 21 11 7.1 3.9 | -11.7 10.9 230 26 13 5.6 3.1
18000 -10.5 13.1 245 20 11 7.0 3.8 | -10.9 12.4 230 25 13 5.8 3.2
17500 -9.4 15.1 245 20 10 6.3 3.5 | -10.0 14.0 235 23 12 6.0 3.3
17000 -8.6 16.5 250 19 10 5.6 3.1 | -9.2 15.4 235 22 11 6.2 3.4
16500 -7.3 18.9 250 17 9 5.4 3.0 | -8.3 17.1 235 20 10 6.2 3.4
16000 -6.5 20.3 250 16 8 5.4 2.9 | -7.3 18.9 235 18 9 6.5 3.6
15500 -5.8 21.6 250 14 7 5.6 3.1 | -5.9 21.4 240 15 8 6.4 3.5
15000 -4.9 23.2 250 13 7 6.5 3.5 | -4.9 23.2 240 13 7 6.1 3.3
14500 -3.9 25.0 250 11 6 6.4 3.5 | -4.0 24.8 240 12 6 6.0 3.3
14000 -2.9 26.8 255 10 5 7.3 4.0 | -3.1 26.4 240 10 5 7.0 3.9
13500 -1.9 28.6 255 9 5 7.2 3.9 | -2.0 28.4 235 9 4 6.9 3.8
13000 -0.8 30.6 260 8 4 7.4 4.1 | -1.0 30.2 235 7 4 7.3 4.0
12500 0.3 32.5 270 7 4 7.4 4.1 | 0.1 32.2 230 6 3 7.3 4.0
12000 1.4 34.5 280 7 4 7.6 4.2 | 1.2 34.2 230 5 3 8.2 4.5
11500 2.5 36.5 285 8 4 7.8 4.3 | 2.5 36.5 230 5 2 8.5 4.6
11000 3.5 38.3 290 9 5 6.2 3.4 | 3.6 38.5 240 4 2 7.0 3.9
10500 4.4 39.9 290 10 5 4.8 2.7 | 4.6 40.3 255 4 2 5.7 3.1
10250 4.9 40.8 295 11 6 10.4 5.7 | 5.1 41.2 265 5 2 10.5 5.8
10000 5.8 42.4 295 11 6 11.4 6.3 | 6.0 42.8 270 5 2 11.0 6.0
9750 6.4 43.5 295 11 6 6.4 3.5 | 6.6 43.9 270 5 2 6.2 3.4
9500 6.9 44.4 295 11 6 8.3 4.5 | 7.1 44.8 275 5 3 7.9 4.3
9250 7.5 45.5 295 11 6 5.8 3.2 | 7.7 45.9 280 5 3 6.0 3.3
9000 7.9 46.2 295 11 6 6.2 3.4 | 8.1 46.6 280 6 3 6.6 3.6
8750 8.5 47.3 295 11 5 8.6 4.7 | 8.7 47.7 280 6 3 8.5 4.7
8500 9.1 48.4 300 10 5 8.6 4.7 | 9.3 48.7 285 5 3 8.3 4.6
8250 9.7 49.5 300 10 5 7.1 3.9 | 9.9 49.8 285 5 2 7.3 4.0
8000 10.1 50.2 305 9 5 5.6 3.0 | 10.4 50.7 285 5 2 6.4 3.5
7750 10.6 51.1 305 8 4 6.5 3.6 | 10.9 51.6 285 4 2 7.4 4.1
7500 11.1 52.0 305 8 4 6.4 3.5 | 11.5 52.7 280 4 2 7.8 4.3
7250 11.5 52.7 305 7 3 4.5 2.5 | 12.0 53.6 275 3 2 5.5 3.0
7000 11.7 53.1 310 6 3 3.1 1.7 | 12.3 54.1 270 3 1 4.0 2.2
6750 12.0 53.6 310 6 3 3.9 2.1 | 12.7 54.9 260 2 1 7.0 3.9
6500 12.2 54.0 305 5 2 0.8 0.4 | 13.3 55.9 240 2 1 8.1 4.5
6250 12.1 53.8 295 4 2 -3.2 -1.8 | 13.8 56.8 220 2 1 7.0 3.8
6000 11.8 53.2 285 4 2 -2.9 -1.6 | 14.4 57.9 205 2 1 6.5 3.5
5750 11.6 52.9 275 3 2 -3.8 -2.1 | 14.9 58.8 190 2 1 8.7 4.8
5500 11.0 51.8 245 3 2 -16.8 -9.2 | 15.8 60.4 180 2 1 16.3 9.0
11/16/2025 at 1400 MST | 11/16/2025 at 1700 MST
|
CAPE... 0.0 LI... +2.8 | CAPE... 0.0 LI... +1.4
CINH... 0.0 K Index... +16.7 | CINH... 0.0 K Index... +20.7
|
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 -62.7 -80.9 245 35 18 0.3 0.2 | -62.0 -79.6 235 35 18 0.8 0.4
45000 -62.1 -79.8 235 39 20 1.7 0.9 | -60.7 -77.3 225 46 23 1.7 0.9
40000 -59.6 -75.3 225 46 23 1.1 0.6 | -58.3 -72.9 220 45 23 1.7 0.9
38000 -55.6 -68.1 220 47 24 7.6 4.1 | -55.5 -67.9 215 48 25 5.9 3.2
36000 -51.1 -60.0 220 48 25 7.6 4.1 | -51.9 -61.4 210 53 27 5.9 3.2
34000 -46.3 -51.3 220 49 25 8.3 4.5 | -47.2 -53.0 210 56 29 8.5 4.7
32000 -41.4 -42.5 225 50 26 8.3 4.5 | -42.1 -43.8 210 53 27 8.5 4.7
30000 -36.5 -33.7 225 49 25 7.9 4.3 | -37.2 -35.0 210 52 27 7.8 4.3
29000 -34.2 -29.6 225 48 25 7.9 4.3 | -34.8 -30.6 210 52 27 7.9 4.3
28000 -31.8 -25.2 225 47 24 7.9 4.3 | -32.5 -26.5 215 52 27 7.9 4.3
27000 -29.6 -21.3 225 46 24 5.7 3.2 | -30.3 -22.5 215 51 26 5.9 3.2
26000 -27.4 -17.3 225 45 23 5.9 3.2 | -28.5 -19.3 215 49 25 6.1 3.3
25000 -25.7 -14.3 225 44 22 5.9 3.2 | -26.7 -16.1 215 47 24 6.1 3.3
24000 -23.8 -10.8 225 43 22 7.6 4.2 | -24.8 -12.6 215 44 23 6.7 3.7
23000 -21.6 -6.9 225 41 21 7.4 4.1 | -22.8 -9.0 220 40 21 6.9 3.8
22000 -19.4 -2.9 225 39 20 7.4 4.1 | -20.7 -5.3 220 37 19 6.9 3.8
21000 -17.2 1.0 225 36 19 7.2 3.9 | -18.6 -1.5 225 33 17 7.8 4.3
20000 -15.1 4.8 225 33 17 7.2 3.9 | -16.3 2.7 225 30 15 7.8 4.3
19500 -14.0 6.8 230 32 16 7.2 3.9 | -15.2 4.6 225 28 15 7.8 4.3
19000 -13.0 8.6 230 30 15 7.3 4.0 | -14.0 6.8 225 27 14 7.8 4.3
18500 -12.0 10.4 230 28 15 6.2 3.4 | -12.9 8.8 225 25 13 7.1 3.9
18000 -11.1 12.0 230 27 14 6.2 3.4 | -11.9 10.6 225 24 12 6.8 3.7
17500 -10.2 13.6 230 25 13 6.2 3.4 | -10.9 12.4 225 22 12 6.7 3.7
17000 -9.3 15.3 230 23 12 6.3 3.4 | -9.9 14.2 225 21 11 6.5 3.6
16500 -8.3 17.1 230 21 11 6.2 3.4 | -8.5 16.7 230 20 10 6.5 3.5
16000 -7.4 18.7 230 19 10 7.0 3.9 | -7.6 18.3 225 20 10 6.2 3.4
15500 -6.4 20.5 230 18 9 7.0 3.8 | -6.7 19.9 225 20 10 6.1 3.3
15000 -5.3 22.5 225 17 9 7.2 4.0 | -5.7 21.7 220 20 10 7.7 4.2
14500 -4.3 24.3 225 16 8 7.3 4.0 | -4.6 23.7 215 19 10 7.5 4.1
14000 -3.2 26.2 220 15 8 7.4 4.1 | -3.5 25.7 210 19 10 8.4 4.6
13500 -2.1 28.2 220 14 7 7.6 4.1 | -2.2 28.0 205 18 9 8.5 4.7
13000 -1.0 30.2 220 14 7 7.5 4.1 | -1.0 30.2 195 17 9 8.2 4.5
12500 0.6 33.1 210 12 6 7.2 3.9 | 0.2 32.4 190 17 9 8.0 4.4
12000 1.7 35.1 205 12 6 8.1 4.5 | 1.4 34.5 180 16 8 8.4 4.6
11500 3.0 37.4 200 11 6 8.5 4.7 | 2.7 36.9 175 17 9 8.8 4.8
11000 4.2 39.6 190 10 5 7.3 4.0 | 4.1 39.4 170 18 9 8.1 4.4
10500 5.2 41.4 185 10 5 5.9 3.2 | 5.2 41.4 165 17 9 6.3 3.4
10250 5.7 42.3 185 10 5 10.5 5.7 | 5.7 42.3 160 17 9 11.4 6.3
10000 6.7 44.1 180 10 5 11.4 6.3 | 6.7 44.1 155 17 9 11.8 6.5
9750 7.3 45.1 175 9 5 7.1 3.9 | 7.3 45.1 155 17 9 7.0 3.8
9500 7.9 46.2 175 9 5 9.2 5.0 | 7.9 46.2 150 17 9 7.8 4.3
9250 8.5 47.3 170 8 4 5.3 2.9 | 8.5 47.3 150 16 8 9.3 5.1
9000 8.8 47.8 170 8 4 5.7 3.1 | 9.3 48.7 145 16 8 9.9 5.4
8750 9.4 48.9 165 8 4 9.2 5.1 | 10.0 50.0 145 16 8 8.3 4.6
8500 10.0 50.0 155 7 4 8.9 4.9 | 10.6 51.1 145 16 8 9.0 4.9
8250 10.7 51.3 150 7 4 6.7 3.7 | 11.3 52.3 140 15 8 8.0 4.4
8000 11.1 52.0 145 7 3 6.0 3.3 | 11.8 53.2 140 15 8 7.2 4.0
7750 11.7 53.1 140 6 3 9.6 5.3 | 12.4 54.3 135 15 8 8.5 4.7
7500 12.4 54.3 135 6 3 10.8 5.9 | 13.1 55.6 130 15 8 9.4 5.2
7250 13.2 55.8 130 5 3 8.6 4.7 | 13.8 56.8 130 15 7 8.3 4.6
7000 13.7 56.7 130 5 3 7.1 3.9 | 14.3 57.7 125 14 7 7.2 4.0
6750 14.4 57.9 130 5 3 10.6 5.8 | 14.9 58.8 120 14 7 8.1 4.4
6500 15.3 59.5 125 5 3 11.7 6.4 | 15.5 59.9 115 14 7 8.9 4.9
6250 16.0 60.8 125 5 2 9.4 5.2 | 16.1 61.0 110 14 7 6.3 3.5
6000 16.7 62.1 120 5 2 8.4 4.6 | 16.5 61.7 110 13 7 4.5 2.5
5750 17.4 63.3 120 4 2 10.8 5.9 | 16.8 62.2 105 12 6 4.0 2.2
5500 18.4 65.1 120 4 2 15.8 8.6 | 16.9 62.4 095 10 5 -4.7 -2.6
________________________________________________________________________________
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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