Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
711
UXUS97 KBOU 160117
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1916 MDT Tuesday, July 15, 2025
This forecast is for Wednesday, July 16, 2025:
If the trigger temperature of 78.7 F/25.9 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 166 ft/min (0.8 m/s)
Maximum height of thermals.................. 10907 ft MSL (5561 ft AGL)
Forecast maximum temperature................... 85.0 F/29.9 C
Time of trigger temperature.................... 1400 MDT
Time of overdevelopment........................ 1600 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................. 9469 ft MSL (4123 ft AGL)
Thermal soaring outlook for Thursday 07/17..... 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)................ Neither
Potential height of wave....................... 23573 ft MSL (18227 ft AGL)
Wave soaring outlook for Thursday 07/17........ Poor
Remarks... Scattered afternoon thunderstorms
Sunrise/Sunset.................... 05:45:17 / 20:25:59 MDT
Total possible sunshine........... 14 hr 40 min 42 sec (880 min 42 sec)
Altitude of sun at 13:05:38 MDT... 71.41 degrees
Upper air data from numerical model forecast valid on 07/16/2025 at 0600 MDT
Freezing level.................. 15984 ft MSL (10638 ft AGL)
Convective condensation level... 13038 ft MSL (7692 ft AGL)
Lifted condensation level....... 12557 ft MSL (7211 ft AGL)
Lifted index.................... -6.3
K index......................... +22.6
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 -82.3 260 27 14 0.9 0.5 M M M M M
45000 -60.1 -76.2 255 34 18 5.4 3.0 M M M M M
40000 -51.9 -61.4 255 38 20 5.6 3.0 M M M M M
38000 -48.6 -55.5 260 39 20 5.6 3.0 M M M M M
36000 -44.8 -48.6 260 40 20 5.9 3.2 M M M M M
34000 -40.3 -40.5 255 36 18 7.7 4.2 M M M M M
32000 -35.7 -32.3 245 31 16 7.5 4.1 M M M M M
30000 -30.9 -23.6 245 31 16 8.1 4.5 44.8 112.7 11.7 M M
29000 -28.4 -19.1 245 31 16 8.2 4.5 44.3 111.7 11.3 M M
28000 -26.0 -14.8 250 30 16 7.6 4.2 43.8 110.8 11.1 M M
27000 -23.8 -10.8 250 29 15 7.3 4.0 42.7 108.9 10.3 M M
26000 -21.6 -6.9 250 28 14 7.3 4.0 41.8 107.2 9.7 M M
25000 -19.5 -3.1 250 26 14 7.3 4.0 41.0 105.8 9.2 M M
24000 -17.3 0.9 255 25 13 7.2 4.0 40.0 104.0 8.5 M M
23000 -15.1 4.8 255 24 12 7.3 4.0 39.1 102.4 7.8 M M
22000 -13.0 8.6 260 22 11 7.3 4.0 38.3 100.9 7.2 M M
21000 -10.8 12.6 265 22 11 7.4 4.1 37.4 99.3 6.5 M M
20000 -8.0 17.6 270 21 11 7.5 4.1 36.4 97.5 5.6 M M
19500 -6.9 19.6 275 21 11 7.3 4.0 36.0 96.9 5.4 M M
19000 -5.9 21.4 275 21 11 6.9 3.8 35.6 96.0 4.9 M M
18500 -4.9 23.2 275 20 10 6.9 3.8 35.1 95.1 4.5 M M
18000 -3.9 25.0 275 19 10 6.7 3.7 34.6 94.2 4.1 M M
17500 -3.0 26.6 280 18 9 6.6 3.6 34.0 93.2 3.6 M M
17000 -2.0 28.4 280 17 9 6.8 3.7 33.5 92.3 3.1 M M
16500 -1.0 30.2 280 16 8 7.4 4.1 33.1 91.5 2.7 M M
16000 0.1 32.2 280 15 8 7.3 4.0 32.7 90.8 2.3 M M
15500 1.3 34.3 280 15 7 8.7 4.8 32.4 90.3 2.0 M M
15000 2.5 36.5 280 14 7 8.7 4.8 32.2 89.9 1.8 M M
14500 3.8 38.8 285 14 7 9.0 4.9 32.0 89.7 1.7 M M
14000 5.2 41.4 285 14 7 9.1 5.0 31.9 89.5 1.6 M M
13500 6.6 43.9 285 14 7 9.0 5.0 31.8 89.3 1.5 M M
13000 7.9 46.2 290 14 7 8.9 4.9 31.7 89.0 1.4 M M
12500 9.2 48.6 290 14 7 8.7 4.8 31.6 88.8 1.2 M M
12000 10.4 50.7 290 14 7 7.8 4.3 31.3 88.3 1.0 M M
11500 11.5 52.7 295 13 7 7.7 4.2 31.0 87.8 0.7 M M
11000 12.5 54.5 295 13 7 5.8 3.2 30.5 86.9 0.1 M M
10500 13.3 55.9 295 12 6 5.5 3.0 29.9 85.8 -0.5 335 1.7
10250 13.6 56.5 295 12 6 2.8 1.6 29.5 85.1 -0.9 318 1.6
10000 13.7 56.7 295 11 6 2.2 1.2 28.9 84.0 -1.6 309 1.6
9750 13.8 56.8 290 10 5 3.2 1.8 28.3 83.0 -2.2 298 1.5
9500 13.9 57.0 290 10 5 2.8 1.5 27.8 82.0 -2.8 287 1.5
9250 13.9 57.0 290 9 5 -0.3 -0.1 27.2 80.9 -3.5 278 1.4
9000 13.7 56.7 290 9 4 -1.9 -1.0 26.3 79.3 -4.4 277 1.4
8750 13.6 56.5 290 8 4 -1.2 -0.6 25.4 77.7 -5.4 275 1.4
8500 13.4 56.1 285 7 3 -0.8 -0.5 24.6 76.2 -6.3 273 1.4
8250 13.3 55.9 285 6 3 0.3 0.2 23.8 74.8 -7.2 269 1.4
8000 13.2 55.8 280 4 2 1.4 0.8 23.1 73.6 -8.0 263 1.3
7750 13.2 55.8 270 3 2 1.7 0.9 22.5 72.5 -8.7 256 1.3
7500 13.2 55.8 245 2 1 3.7 2.0 21.9 71.4 -9.4 247 1.3
7250 13.6 56.5 235 1 1 5.9 3.2 21.6 70.8 -9.9 230 1.2
7000 14.0 57.2 000 0 0 5.9 3.2 21.3 70.3 -10.2 211 1.1
6750 14.4 57.9 085 1 0 6.0 3.3 21.0 69.8 -10.6 191 1.0
6500 14.8 58.6 070 2 1 6.4 3.5 20.7 69.3 -10.9 171 0.9
6250 15.3 59.5 055 2 1 6.8 3.7 20.5 68.9 -11.2 149 0.8
6000 15.8 60.4 050 3 1 6.3 3.4 20.2 68.4 -11.4 128 0.6
5750 16.2 61.2 040 3 2 7.9 4.3 20.0 68.0 -11.7 106 0.5
5500 17.0 62.6 040 3 2 12.2 6.7 20.0 68.1 -11.7 76 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/16/2025 at 0900 MDT | 07/16/2025 at 1200 MDT
|
CAPE... +1399.1 LI... -4.3 | CAPE... +1656.7 LI... -4.9
CINH... -143.3 K Index... +23.2 | CINH... -90.9 K Index... +25.6
|
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 -62.9 -81.2 260 26 13 1.2 0.7 | -62.9 -81.2 245 25 13 1.7 1.0
45000 -59.6 -75.3 255 39 20 4.6 2.5 | -59.1 -74.4 250 40 20 4.3 2.4
40000 -52.5 -62.5 260 43 22 5.6 3.1 | -52.4 -62.3 255 48 25 5.7 3.1
38000 -48.8 -55.8 255 41 21 5.6 3.1 | -49.0 -56.2 255 45 23 5.7 3.1
36000 -45.4 -49.7 255 39 20 5.7 3.1 | -45.2 -49.4 255 41 21 5.7 3.1
34000 -40.9 -41.6 250 37 19 7.7 4.2 | -41.0 -41.8 250 39 20 7.1 3.9
32000 -36.3 -33.3 240 34 18 7.5 4.1 | -36.7 -34.1 240 38 19 6.9 3.8
30000 -31.5 -24.7 240 33 17 8.0 4.4 | -32.2 -26.0 245 36 19 7.5 4.1
29000 -29.1 -20.4 240 32 17 8.0 4.4 | -30.0 -22.0 245 36 18 7.6 4.1
28000 -26.7 -16.1 245 32 16 7.4 4.1 | -27.7 -17.9 250 35 18 7.4 4.0
27000 -24.6 -12.3 245 30 16 7.0 3.9 | -25.6 -14.1 250 33 17 7.3 4.0
26000 -22.5 -8.5 250 29 15 7.1 3.9 | -23.4 -10.1 255 32 16 7.3 4.0
25000 -20.4 -4.7 255 28 14 7.1 3.9 | -21.3 -6.3 255 30 16 7.3 4.0
24000 -18.4 -1.1 255 25 13 7.1 3.9 | -19.0 -2.2 255 29 15 7.7 4.2
23000 -16.3 2.7 260 22 12 7.1 3.9 | -16.8 1.8 255 29 15 7.7 4.2
22000 -14.2 6.4 265 20 10 7.2 4.0 | -14.5 5.9 255 28 14 7.8 4.3
21000 -11.9 10.6 275 19 10 7.8 4.3 | -12.1 10.2 260 26 13 8.0 4.4
20000 -9.1 15.6 280 19 10 7.8 4.3 | -9.2 15.4 265 24 12 8.1 4.4
19500 -7.9 17.8 285 19 10 7.8 4.3 | -8.0 17.6 265 23 12 7.9 4.4
19000 -6.8 19.8 285 19 10 7.8 4.3 | -6.9 19.6 270 22 12 7.7 4.2
18500 -5.7 21.7 290 19 10 7.8 4.3 | -5.8 21.6 270 22 11 7.6 4.2
18000 -4.5 23.9 290 20 10 8.0 4.4 | -4.6 23.7 275 21 11 8.1 4.5
17500 -3.3 26.1 290 20 10 8.1 4.4 | -3.4 25.9 275 20 10 8.2 4.5
17000 -2.1 28.2 290 20 10 8.2 4.5 | -2.2 28.0 275 20 10 8.4 4.6
16500 -0.9 30.4 290 20 10 8.5 4.7 | -0.9 30.4 280 19 10 8.9 4.9
16000 0.4 32.7 290 19 10 8.5 4.7 | 0.4 32.7 280 19 10 8.8 4.8
15500 1.6 34.9 285 19 10 8.8 4.8 | 1.7 35.1 280 19 10 9.2 5.0
15000 2.9 37.2 285 18 9 8.8 4.8 | 3.1 37.6 280 18 9 9.2 5.0
14500 4.2 39.6 285 18 9 8.8 4.8 | 4.4 39.9 285 18 9 9.1 5.0
14000 5.5 41.9 280 17 9 8.7 4.8 | 5.8 42.4 285 18 9 9.1 5.0
13500 6.8 44.2 280 16 8 8.6 4.7 | 7.1 44.8 285 17 9 9.1 5.0
13000 8.1 46.6 280 15 8 8.5 4.7 | 8.5 47.3 285 16 8 9.1 5.0
12500 9.4 48.9 280 14 7 8.4 4.6 | 9.8 49.6 285 15 8 9.0 4.9
12000 10.6 51.1 275 13 7 8.1 4.5 | 11.1 52.0 280 13 7 8.7 4.8
11500 11.8 53.2 275 12 6 8.0 4.4 | 12.4 54.3 280 12 6 8.5 4.7
11000 12.9 55.2 275 11 6 6.6 3.6 | 13.5 56.3 275 10 5 6.8 3.7
10500 13.8 56.8 270 10 5 4.8 2.6 | 14.5 58.1 270 9 4 4.0 2.2
10250 14.1 57.4 275 10 5 2.8 1.5 | 14.7 58.5 270 8 4 3.3 1.8
10000 14.3 57.7 270 9 5 5.0 2.7 | 15.1 59.2 265 7 4 6.8 3.7
9750 14.7 58.5 270 9 4 5.7 3.1 | 15.5 59.9 260 6 3 6.2 3.4
9500 15.1 59.2 265 8 4 4.7 2.6 | 15.9 60.6 250 5 3 5.3 2.9
9250 15.2 59.4 260 7 4 1.3 0.7 | 16.1 61.0 240 4 2 2.3 1.3
9000 15.1 59.2 260 7 4 -2.0 -1.1 | 16.2 61.2 230 3 2 3.6 2.0
8750 14.8 58.6 255 6 3 -2.8 -1.5 | 16.6 61.9 215 3 1 5.7 3.2
8500 14.5 58.1 250 5 3 -2.1 -1.1 | 16.9 62.4 190 2 1 4.8 2.7
8250 14.2 57.6 245 5 2 -1.9 -1.1 | 17.1 62.8 150 2 1 3.2 1.8
8000 14.0 57.2 235 4 2 -0.3 -0.2 | 17.2 63.0 125 3 2 5.2 2.9
7750 13.9 57.0 230 3 1 1.4 0.7 | 17.7 63.9 110 4 2 8.3 4.6
7500 13.9 57.0 225 2 1 4.2 2.3 | 18.2 64.8 105 4 2 8.0 4.4
7250 14.3 57.7 195 1 1 6.6 3.6 | 18.7 65.7 100 4 2 7.5 4.1
7000 14.7 58.5 150 1 1 6.6 3.6 | 19.3 66.7 095 4 2 8.3 4.6
6750 15.3 59.5 120 2 1 9.5 5.2 | 20.0 68.0 095 4 2 11.7 6.4
6500 16.0 60.8 100 2 1 9.9 5.5 | 20.9 69.6 090 4 2 11.3 6.2
6250 16.6 61.9 095 2 1 8.8 4.8 | 21.6 70.9 085 4 2 9.9 5.4
6000 17.3 63.1 095 3 1 8.5 4.7 | 22.4 72.3 085 4 2 9.1 5.0
5750 18.0 64.4 090 3 1 12.4 6.8 | 23.2 73.8 080 4 2 15.4 8.4
5500 19.2 66.6 085 3 1 20.8 11.4 | 24.8 76.6 075 4 2 31.3 17.2
07/16/2025 at 1500 MDT | 07/16/2025 at 1800 MDT
|
CAPE... +1006.3 LI... -3.6 | CAPE... +711.4 LI... -2.8
CINH... -48.7 K Index... +30.6 | CINH... -62.7 K Index... +28.9
|
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 -64.1 -83.4 245 32 16 1.1 0.6 | -64.9 -84.8 250 30 16 1.0 0.5
45000 -60.6 -77.1 245 44 23 5.2 2.9 | -61.3 -78.3 245 38 20 5.7 3.1
40000 -52.0 -61.6 240 49 25 7.0 3.8 | -52.1 -61.8 240 44 22 7.2 3.9
38000 -47.8 -54.0 240 48 25 7.0 3.8 | -47.8 -54.0 240 45 23 7.2 3.9
36000 -43.6 -46.5 240 47 24 7.0 3.8 | -43.5 -46.3 240 46 24 7.3 4.0
34000 -39.2 -38.6 240 46 24 7.4 4.0 | -38.7 -37.7 240 46 24 8.2 4.5
32000 -34.8 -30.6 235 45 23 7.2 4.0 | -33.8 -28.8 240 46 24 8.1 4.4
30000 -30.3 -22.5 240 44 23 7.7 4.2 | -29.0 -20.2 240 43 22 7.9 4.3
29000 -28.0 -18.4 245 44 23 7.7 4.2 | -26.7 -16.1 240 42 21 7.9 4.3
28000 -25.7 -14.3 245 44 22 7.4 4.1 | -23.8 -10.8 245 39 20 6.4 3.5
27000 -23.1 -9.6 250 42 22 6.9 3.8 | -21.9 -7.4 250 38 20 6.5 3.6
26000 -21.1 -6.0 255 41 21 6.9 3.8 | -20.0 -4.0 255 37 19 6.5 3.6
25000 -19.0 -2.2 260 40 21 6.7 3.7 | -18.1 -0.6 260 37 19 6.5 3.6
24000 -17.2 1.0 260 41 21 6.2 3.4 | -16.1 3.0 265 36 19 6.5 3.6
23000 -15.4 4.3 265 41 21 6.2 3.4 | -14.2 6.4 275 35 18 6.5 3.6
22000 -13.6 7.5 270 42 22 6.8 3.8 | -12.3 9.9 280 35 18 6.6 3.6
21000 -11.4 11.5 270 40 20 7.7 4.2 | -10.3 13.5 280 34 18 6.9 3.8
20000 -9.2 15.4 275 37 19 7.8 4.3 | -8.3 17.1 285 33 17 7.0 3.8
19500 -8.1 17.4 280 36 19 7.8 4.3 | -7.4 18.7 285 33 17 7.0 3.8
19000 -6.9 19.6 280 34 18 7.7 4.2 | -6.3 20.7 290 33 17 7.2 3.9
18500 -5.8 21.6 280 32 16 7.7 4.2 | -5.3 22.5 290 32 17 7.2 3.9
18000 -4.7 23.5 285 29 15 7.7 4.2 | -4.3 24.3 290 32 17 7.3 4.0
17500 -3.6 25.5 285 26 14 7.7 4.2 | -3.2 26.2 290 31 16 7.4 4.1
17000 -2.5 27.5 285 23 12 7.7 4.2 | -2.1 28.2 295 30 15 7.4 4.0
16500 -1.4 29.5 285 21 11 7.3 4.0 | -1.0 30.2 295 28 14 8.3 4.5
16000 -0.4 31.3 285 18 9 7.4 4.1 | 0.1 32.2 295 25 13 8.2 4.5
15500 0.7 33.3 285 15 8 7.6 4.2 | 1.3 34.3 295 22 11 7.6 4.2
15000 1.8 35.2 280 13 7 7.7 4.2 | 2.3 36.1 295 19 10 7.2 3.9
14500 2.9 37.2 280 11 6 7.8 4.3 | 3.8 38.8 290 14 7 7.2 3.9
14000 4.1 39.4 270 9 5 8.0 4.4 | 4.8 40.6 285 11 6 7.2 4.0
13500 5.2 41.4 260 8 4 8.0 4.4 | 5.9 42.6 275 9 5 7.3 4.0
13000 7.1 44.8 245 7 3 8.4 4.6 | 6.9 44.4 260 7 4 7.4 4.1
12500 8.3 46.9 230 6 3 8.3 4.6 | 8.0 46.4 240 6 3 7.4 4.1
12000 9.5 49.1 220 6 3 8.3 4.5 | 9.1 48.4 220 6 3 7.3 4.0
11500 10.8 51.4 210 7 3 8.3 4.5 | 10.2 50.4 200 6 3 7.2 3.9
11000 12.0 53.6 205 7 4 8.0 4.4 | 11.1 52.0 185 7 4 6.6 3.6
10500 13.2 55.8 195 8 4 3.2 1.8 | 12.1 53.8 175 8 4 3.8 2.1
10250 13.3 55.9 195 7 4 4.0 2.2 | 12.3 54.1 170 8 4 4.6 2.5
10000 14.0 57.2 190 7 4 11.0 6.0 | 12.9 55.2 170 9 5 9.0 4.9
9750 14.6 58.3 180 7 4 9.6 5.3 | 13.4 56.1 165 10 5 8.1 4.4
9500 15.3 59.5 170 7 4 8.3 4.5 | 14.0 57.2 165 11 6 7.4 4.0
9250 15.8 60.4 165 7 4 6.3 3.4 | 14.4 57.9 165 12 6 5.0 2.7
9000 16.3 61.3 165 7 4 8.4 4.6 | 14.8 58.6 165 12 6 5.5 3.0
8750 16.9 62.4 160 8 4 9.9 5.4 | 15.2 59.4 160 13 7 6.6 3.6
8500 17.5 63.5 155 9 5 8.5 4.6 | 15.6 60.1 160 14 7 5.9 3.2
8250 18.0 64.4 155 9 5 6.6 3.6 | 16.0 60.8 160 15 8 4.7 2.6
8000 18.6 65.5 150 9 5 8.0 4.4 | 16.4 61.5 160 16 8 5.8 3.2
7750 19.2 66.6 150 10 5 9.7 5.3 | 16.9 62.4 155 16 8 8.0 4.4
7500 19.9 67.8 145 11 6 8.4 4.6 | 17.4 63.3 155 17 9 6.5 3.6
7250 20.4 68.7 145 11 6 7.2 3.9 | 17.8 64.0 155 17 9 5.0 2.7
7000 21.0 69.8 145 12 6 8.0 4.4 | 18.2 64.8 155 18 9 5.3 2.9
6750 21.6 70.9 140 12 6 9.4 5.2 | 18.5 65.3 155 18 9 5.5 3.0
6500 22.3 72.1 140 13 7 9.3 5.1 | 18.9 66.0 150 18 9 7.0 3.9
6250 22.9 73.2 140 13 7 8.9 4.9 | 19.5 67.1 150 17 9 8.2 4.5
6000 23.6 74.5 135 13 7 8.6 4.7 | 20.0 68.0 150 17 9 6.9 3.8
5750 24.3 75.7 135 13 7 14.1 7.7 | 20.6 69.1 150 16 8 11.3 6.2
5500 25.7 78.3 135 12 6 24.6 13.5 | 21.8 71.2 150 14 7 21.8 12.0
________________________________________________________________________________
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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