Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
566
UXUS97 KBOU 151325
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0724 MDT Tuesday, July 15, 2025
This forecast is for Tuesday, July 15, 2025:
If the trigger temperature of 88.9 F/31.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1281 ft/min (6.5 m/s)
Maximum height of thermals.................. 20199 ft MSL (14868 ft AGL)
Forecast maximum temperature................... 95.0 F/35.5 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ None
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................. 10698 ft MSL (5367 ft AGL)
Thermal soaring outlook for Wednesday 07/16.... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Trending the same
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 19140 ft MSL (13809 ft AGL)
Wave soaring outlook for Wednesday 07/16....... Fair
Remarks...
Sunrise/Sunset.................... 05:44:31 / 20:26:34 MDT
Total possible sunshine........... 14 hr 42 min 4 sec (882 min 4 sec)
Altitude of sun at 13:05:33 MDT... 71.58 degrees
Upper air data from numerical model forecast valid on 07/15/2025 at 0600 MDT
Freezing level.................. 16443 ft MSL (11112 ft AGL)
Convective condensation level... 19827 ft MSL (14496 ft AGL)
Lifted condensation level....... 20025 ft MSL (14694 ft AGL)
Lifted index.................... -1.6
K index......................... +14.5
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 -63.0 -81.4 300 24 12 1.9 1.0 M M M M M
45000 -59.1 -74.4 295 31 16 4.3 2.3 M M M M M
40000 -52.4 -62.3 270 34 18 6.3 3.5 M M M M M
38000 -48.1 -54.6 265 34 18 6.3 3.5 M M M M M
36000 -44.3 -47.7 260 34 18 6.5 3.5 M M M M M
34000 -39.8 -39.6 260 31 16 7.6 4.2 M M M M M
32000 -35.2 -31.4 270 29 15 7.7 4.2 M M M M M
30000 -31.2 -24.2 270 23 12 6.5 3.6 44.1 111.3 6.9 M M
29000 -29.3 -20.7 270 21 11 6.5 3.6 42.8 109.1 6.0 M M
28000 -27.3 -17.1 270 18 9 6.8 3.7 41.7 107.1 5.2 M M
27000 -25.2 -13.4 265 16 8 7.0 3.8 40.6 105.0 4.4 M M
26000 -23.1 -9.6 265 14 7 7.0 3.9 39.5 103.1 3.6 M M
25000 -21.0 -5.8 265 12 6 7.1 3.9 38.6 101.5 2.9 M M
24000 -18.7 -1.7 270 12 6 7.9 4.4 37.8 100.1 2.2 M M
23000 -16.3 2.7 280 13 7 7.9 4.4 37.1 98.8 1.7 M M
22000 -14.0 6.8 285 14 7 7.9 4.3 36.6 97.8 1.2 M M
21000 -11.6 11.1 290 16 8 7.8 4.3 35.8 96.5 0.6 M M
20000 -8.7 16.3 295 19 10 7.8 4.3 35.0 95.0 -0.2 1449 7.4
19500 -7.6 18.3 295 20 10 8.0 4.4 34.7 94.5 -0.4 1399 7.1
19000 -6.4 20.5 295 20 11 8.3 4.6 34.4 94.0 -0.7 1348 6.8
18500 -5.1 22.8 295 21 11 8.3 4.6 34.2 93.5 -1.0 1297 6.6
18000 -3.9 25.0 295 21 11 8.8 4.8 34.0 93.1 -1.2 1244 6.3
17500 -2.6 27.3 295 21 11 8.8 4.8 33.8 92.8 -1.4 1191 6.0
17000 -1.3 29.7 295 20 10 9.0 4.9 33.6 92.6 -1.5 1137 5.8
16500 0.0 32.0 295 19 10 9.3 5.1 33.5 92.4 -1.7 1082 5.5
16000 1.4 34.5 295 19 10 9.2 5.1 33.5 92.2 -1.8 1026 5.2
15500 2.8 37.0 295 18 9 9.6 5.3 33.4 92.1 -1.9 970 4.9
15000 4.2 39.6 295 17 9 9.6 5.2 33.4 92.1 -1.9 912 4.6
14500 5.6 42.1 295 16 8 9.5 5.2 33.3 92.0 -2.0 855 4.3
14000 7.0 44.6 300 16 8 9.5 5.2 33.3 91.9 -2.1 798 4.1
13500 8.4 47.1 300 15 8 9.4 5.2 33.3 91.9 -2.1 741 3.8
13000 9.8 49.6 300 15 8 9.4 5.1 33.2 91.7 -2.2 685 3.5
12500 11.2 52.2 305 14 7 9.3 5.1 33.1 91.6 -2.3 628 3.2
12000 12.6 54.7 305 14 7 9.2 5.1 33.0 91.5 -2.4 573 2.9
11500 13.9 57.0 305 15 8 9.0 4.9 33.0 91.3 -2.5 517 2.6
11000 15.1 59.2 305 15 8 7.7 4.2 32.7 90.8 -2.8 466 2.4
10500 16.3 61.3 305 15 8 11.4 6.3 32.3 90.2 -3.1 418 2.1
10250 17.3 63.1 305 15 8 12.1 6.6 32.7 90.8 -2.8 379 1.9
10000 17.9 64.2 305 16 8 7.7 4.2 32.6 90.7 -2.9 353 1.8
9750 18.6 65.5 305 16 8 9.0 5.0 32.5 90.5 -3.0 326 1.7
9500 19.2 66.6 305 16 8 8.1 4.5 32.4 90.4 -3.1 299 1.5
9250 19.8 67.6 305 16 8 7.3 4.0 32.3 90.1 -3.3 274 1.4
9000 20.4 68.7 305 16 8 8.5 4.6 32.1 89.8 -3.4 250 1.3
8750 21.1 70.0 305 17 9 9.5 5.2 32.0 89.7 -3.5 222 1.1
8500 21.7 71.1 305 17 9 9.0 4.9 32.0 89.6 -3.6 194 1.0
8250 22.4 72.3 305 18 9 8.1 4.4 31.9 89.5 -3.7 168 0.9
8000 23.0 73.4 305 18 9 7.7 4.2 31.8 89.2 -3.8 143 0.7
7750 23.5 74.3 305 19 10 8.2 4.5 31.6 88.9 -4.0 118 0.6
7500 24.1 75.4 300 19 10 7.2 4.0 31.5 88.7 -4.1 93 0.5
7250 24.6 76.3 300 19 10 6.0 3.3 31.2 88.2 -4.4 72 0.4
7000 25.0 77.0 300 20 10 4.8 2.6 30.9 87.7 -4.7 52 0.3
6750 25.3 77.5 295 20 10 4.1 2.3 30.5 86.9 -5.2 36 0.2
6500 25.4 77.7 290 18 9 -2.1 -1.1 29.9 85.9 -5.8 25 0.1
6250 24.9 76.8 285 17 9 -7.7 -4.2 28.7 83.7 -7.1 34 0.2
6000 24.3 75.7 285 15 8 -5.2 -2.9 27.5 81.5 -8.4 43 0.2
5750 23.7 74.7 275 14 7 -11.9 -6.5 26.2 79.2 -9.8 53 0.3
5500 22.1 71.8 260 9 5 -29.8 -16.4 23.9 75.1 -12.1 95 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/15/2025 at 0900 MDT | 07/15/2025 at 1200 MDT
|
CAPE... +51.4 LI... +0.8 | CAPE... +140.7 LI... +0.3
CINH... -96.3 K Index... +14.3 | CINH... -33.6 K Index... +19.7
|
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 -62.2 -80.0 300 17 9 1.2 0.7 | -62.4 -80.3 295 13 7 1.0 0.5
45000 -58.8 -73.8 290 23 12 4.5 2.5 | -59.1 -74.4 280 18 9 5.2 2.8
40000 -51.8 -61.2 275 30 15 6.2 3.4 | -50.7 -59.3 270 27 14 6.6 3.6
38000 -47.6 -53.7 270 31 16 6.2 3.4 | -46.8 -52.2 265 28 15 6.6 3.6
36000 -43.9 -47.0 265 33 17 6.2 3.4 | -42.8 -45.0 260 30 16 6.8 3.7
34000 -39.8 -39.6 260 31 16 6.8 3.8 | -39.8 -39.6 260 33 17 4.8 2.6
32000 -35.7 -32.3 255 29 15 6.8 3.7 | -36.9 -34.4 265 36 18 4.7 2.6
30000 -31.7 -25.1 265 23 12 6.6 3.6 | -32.9 -27.2 265 34 17 7.3 4.0
29000 -29.7 -21.5 270 20 10 6.6 3.6 | -30.7 -23.3 270 32 16 7.3 4.0
28000 -27.7 -17.9 280 18 9 7.0 3.8 | -28.0 -18.4 270 30 15 7.7 4.2
27000 -25.6 -14.1 280 17 9 7.2 3.9 | -25.7 -14.3 270 28 15 7.7 4.2
26000 -23.4 -10.1 280 15 8 7.2 3.9 | -23.4 -10.1 270 27 14 7.8 4.3
25000 -21.3 -6.3 280 14 7 7.2 4.0 | -21.1 -6.0 270 25 13 7.6 4.2
24000 -19.0 -2.2 285 13 7 7.7 4.2 | -19.0 -2.2 270 24 12 7.3 4.0
23000 -16.7 1.9 290 13 7 7.7 4.2 | -16.8 1.8 270 23 12 7.3 4.0
22000 -14.4 6.1 290 12 6 7.7 4.2 | -14.7 5.5 270 21 11 7.8 4.3
21000 -12.2 10.0 300 14 7 7.7 4.2 | -12.2 10.0 275 21 11 8.3 4.6
20000 -9.3 15.3 310 16 8 7.9 4.3 | -9.8 14.4 280 20 10 8.3 4.6
19500 -8.2 17.2 315 18 9 8.1 4.5 | -8.6 16.5 280 20 10 8.3 4.6
19000 -6.9 19.6 315 18 9 8.7 4.7 | -7.3 18.9 285 20 10 8.6 4.7
18500 -5.7 21.7 315 19 10 8.7 4.8 | -6.1 21.0 285 21 11 8.6 4.7
18000 -4.4 24.1 310 20 10 8.7 4.7 | -4.8 23.4 290 21 11 8.6 4.7
17500 -3.1 26.4 310 20 10 8.7 4.8 | -3.5 25.7 290 21 11 8.7 4.8
17000 -1.8 28.8 310 21 11 8.8 4.8 | -2.2 28.0 290 21 11 8.7 4.8
16500 -0.5 31.1 310 21 11 9.0 4.9 | -0.9 30.4 295 21 11 8.9 4.9
16000 0.9 33.6 305 21 11 9.0 4.9 | 0.4 32.7 295 21 11 8.9 4.9
15500 2.2 36.0 305 20 11 9.2 5.0 | 1.7 35.1 295 21 11 9.0 4.9
15000 3.6 38.5 305 20 10 9.2 5.0 | 3.0 37.4 295 20 11 9.0 5.0
14500 5.0 41.0 305 19 10 9.2 5.1 | 5.0 41.0 300 20 10 9.1 5.0
14000 6.3 43.3 305 18 10 9.3 5.1 | 6.4 43.5 300 19 10 9.1 5.0
13500 7.7 45.9 305 18 9 9.2 5.1 | 7.7 45.9 300 18 9 9.2 5.0
13000 9.1 48.4 305 17 9 9.2 5.1 | 9.1 48.4 305 18 9 9.2 5.1
12500 10.4 50.7 305 16 8 9.2 5.1 | 10.5 50.9 305 17 9 9.3 5.1
12000 11.8 53.2 305 16 8 9.3 5.1 | 11.9 53.4 310 16 8 9.4 5.1
11500 13.2 55.8 305 17 9 9.3 5.1 | 13.2 55.8 310 15 8 9.4 5.1
11000 14.6 58.3 305 16 8 8.9 4.9 | 14.7 58.5 310 15 8 9.1 5.0
10500 15.9 60.6 305 16 8 5.4 3.0 | 16.1 61.0 315 14 7 4.6 2.5
10250 16.2 61.2 310 16 8 6.3 3.4 | 16.2 61.2 315 14 7 6.1 3.3
10000 17.0 62.6 310 16 8 11.6 6.3 | 17.1 62.8 315 13 7 12.9 7.1
9750 17.8 64.0 310 15 8 10.4 5.7 | 17.9 64.2 315 13 7 11.9 6.5
9500 18.5 65.3 310 15 8 9.8 5.4 | 18.8 65.8 315 13 7 9.0 4.9
9250 19.2 66.6 310 15 8 8.1 4.5 | 19.3 66.7 320 12 6 7.3 4.0
9000 19.8 67.6 310 16 8 9.0 4.9 | 20.0 68.0 320 12 6 11.1 6.1
8750 20.5 68.9 310 16 8 9.9 5.5 | 20.9 69.6 320 12 6 12.1 6.6
8500 21.2 70.2 310 16 8 9.2 5.0 | 21.7 71.1 320 13 6 10.2 5.6
8250 21.9 71.4 310 16 8 7.5 4.1 | 22.4 72.3 320 12 6 7.2 3.9
8000 22.4 72.3 310 16 8 8.2 4.5 | 22.9 73.2 325 12 6 9.8 5.3
7750 23.1 73.6 310 15 8 10.0 5.5 | 23.8 74.8 325 12 6 13.0 7.1
7500 23.8 74.8 310 15 8 8.1 4.5 | 24.7 76.5 325 12 6 9.8 5.4
7250 24.3 75.7 310 15 8 6.0 3.3 | 25.3 77.5 325 12 6 6.5 3.6
7000 24.7 76.5 310 15 8 5.9 3.3 | 25.8 78.4 325 12 6 9.3 5.1
6750 25.2 77.4 305 15 8 6.1 3.3 | 26.7 80.1 325 12 6 14.0 7.7
6500 25.6 78.1 305 14 7 5.6 3.1 | 27.7 81.9 325 12 6 11.8 6.5
6250 25.9 78.6 300 12 6 5.5 3.0 | 28.5 83.3 325 11 6 9.1 5.0
6000 26.3 79.3 300 11 5 4.8 2.7 | 29.2 84.6 330 11 6 9.1 5.0
5750 26.7 80.1 295 9 5 7.4 4.1 | 30.0 86.0 330 11 6 14.8 8.1
5500 27.5 81.5 290 7 4 16.8 9.2 | 31.6 88.9 330 10 5 28.9 15.8
07/15/2025 at 1500 MDT | 07/15/2025 at 1800 MDT
|
CAPE... +182.6 LI... -0.5 | CAPE... +132.0 LI... +0.1
CINH... -14.5 K Index... +22.9 | CINH... -100.1 K Index... +22.1
|
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 -63.0 -81.4 280 15 8 0.2 0.1 | -63.3 -81.9 275 14 7 0.6 0.4
45000 -60.1 -76.2 275 24 12 6.1 3.3 | -60.2 -76.4 280 25 13 5.5 3.0
40000 -50.4 -58.7 260 27 14 6.4 3.5 | -51.3 -60.3 270 30 16 6.3 3.5
38000 -46.6 -51.9 260 31 16 6.4 3.5 | -47.5 -53.5 270 32 16 6.4 3.5
36000 -42.7 -44.9 265 34 18 6.7 3.6 | -43.7 -46.7 270 33 17 6.4 3.5
34000 -39.8 -39.6 265 37 19 4.6 2.5 | -40.0 -40.0 270 33 17 6.2 3.4
32000 -37.1 -34.8 270 39 20 4.5 2.5 | -36.3 -33.3 270 32 17 6.0 3.3
30000 -32.7 -26.9 270 38 20 8.0 4.4 | -31.4 -24.5 275 32 17 7.7 4.2
29000 -29.8 -21.6 270 37 19 8.0 4.4 | -29.1 -20.4 280 32 17 7.7 4.2
28000 -27.4 -17.3 270 36 19 7.7 4.2 | -26.8 -16.2 280 33 17 7.6 4.2
27000 -25.1 -13.2 270 35 18 7.7 4.2 | -24.6 -12.3 280 32 17 7.6 4.2
26000 -22.8 -9.0 275 35 18 7.8 4.3 | -22.3 -8.1 280 32 17 7.7 4.2
25000 -20.5 -4.9 275 34 17 7.6 4.2 | -20.1 -4.2 280 32 16 7.6 4.2
24000 -18.4 -1.1 280 32 17 7.3 4.0 | -17.9 -0.2 280 31 16 7.4 4.0
23000 -16.2 2.8 280 31 16 7.3 4.0 | -15.7 3.7 280 29 15 7.4 4.0
22000 -14.1 6.6 285 30 15 7.4 4.1 | -13.5 7.7 285 28 14 7.5 4.1
21000 -11.9 10.6 290 28 15 7.5 4.1 | -11.2 11.8 285 25 13 7.7 4.3
20000 -9.7 14.5 290 27 14 7.5 4.1 | -8.9 16.0 290 23 12 7.8 4.3
19500 -8.7 16.3 290 26 13 7.5 4.1 | -7.8 18.0 290 21 11 7.7 4.2
19000 -7.5 18.5 290 25 13 8.2 4.5 | -6.6 20.1 290 20 10 8.2 4.5
18500 -6.3 20.7 295 24 12 8.2 4.5 | -5.5 22.1 295 19 10 8.2 4.5
18000 -5.1 22.8 295 23 12 8.7 4.8 | -4.3 24.3 295 18 9 8.3 4.5
17500 -3.8 25.2 295 22 11 9.2 5.0 | -2.4 27.7 295 16 8 8.4 4.6
17000 -2.4 27.7 295 21 11 9.2 5.1 | -1.2 29.8 300 15 8 8.5 4.7
16500 -1.0 30.2 295 19 10 9.5 5.2 | 0.0 32.0 300 14 7 8.6 4.7
16000 0.4 32.7 300 18 9 9.5 5.2 | 1.3 34.3 300 12 6 8.7 4.7
15500 1.8 35.2 300 17 9 9.5 5.2 | 2.6 36.7 300 11 6 9.0 5.0
15000 3.9 39.0 300 16 8 9.5 5.2 | 3.9 39.0 300 10 5 9.0 4.9
14500 5.4 41.7 300 14 7 9.4 5.2 | 5.3 41.5 300 9 5 9.0 5.0
14000 6.8 44.2 305 13 7 9.4 5.2 | 6.6 43.9 305 8 4 9.0 5.0
13500 8.2 46.8 305 12 6 9.5 5.2 | 7.9 46.2 305 8 4 9.0 4.9
13000 9.6 49.3 305 11 6 9.5 5.2 | 9.3 48.7 300 7 3 9.0 4.9
12500 11.0 51.8 305 10 5 9.4 5.2 | 10.6 51.1 300 6 3 9.0 4.9
12000 12.4 54.3 305 9 5 9.3 5.1 | 11.9 53.4 300 5 3 9.0 4.9
11500 13.7 56.7 305 9 5 9.3 5.1 | 13.2 55.8 295 4 2 8.8 4.8
11000 15.1 59.2 305 8 4 9.2 5.0 | 14.4 57.9 285 4 2 7.9 4.3
10500 16.6 61.9 300 8 4 5.2 2.8 | 15.6 60.1 280 4 2 11.0 6.1
10250 16.8 62.2 305 8 4 6.5 3.6 | 16.6 61.9 270 3 2 11.8 6.5
10000 17.7 63.9 300 8 4 12.7 7.0 | 17.2 63.0 260 3 2 8.1 4.4
9750 18.5 65.3 300 7 4 11.6 6.4 | 17.9 64.2 255 3 1 9.2 5.1
9500 19.4 66.9 295 7 4 9.7 5.3 | 18.5 65.3 245 3 1 8.4 4.6
9250 20.0 68.0 295 7 4 7.9 4.4 | 19.1 66.4 240 3 2 7.8 4.3
9000 20.7 69.3 295 7 4 10.1 5.6 | 19.7 67.5 235 4 2 8.5 4.6
8750 21.4 70.5 290 7 3 10.8 5.9 | 20.4 68.7 225 4 2 9.0 4.9
8500 22.2 72.0 290 7 3 9.8 5.4 | 21.0 69.8 220 4 2 8.5 4.7
8250 22.9 73.2 285 6 3 8.0 4.4 | 21.6 70.9 215 4 2 7.2 3.9
8000 23.5 74.3 285 6 3 9.3 5.1 | 22.1 71.8 220 5 2 7.2 4.0
7750 24.3 75.7 280 6 3 11.2 6.1 | 22.6 72.7 215 5 2 8.0 4.4
7500 25.1 77.2 280 6 3 9.4 5.2 | 23.2 73.8 210 4 2 7.2 4.0
7250 25.7 78.3 275 6 3 7.5 4.1 | 23.7 74.7 210 5 2 6.0 3.3
7000 26.3 79.3 275 6 3 8.6 4.7 | 24.1 75.4 215 5 3 6.7 3.7
6750 27.0 80.6 270 6 3 11.2 6.2 | 24.7 76.5 215 5 3 8.7 4.8
6500 27.8 82.0 265 6 3 10.7 5.8 | 25.3 77.5 210 5 3 9.8 5.4
6250 28.6 83.5 265 6 3 9.6 5.3 | 26.1 79.0 215 5 3 10.2 5.6
6000 29.3 84.7 265 6 3 9.2 5.0 | 26.8 80.2 215 5 3 9.6 5.3
5750 30.0 86.0 260 6 3 13.3 7.3 | 27.5 81.5 220 5 3 10.8 5.9
5500 31.4 88.5 265 5 3 25.6 14.0 | 28.5 83.3 215 4 2 17.3 9.5
________________________________________________________________________________
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.
042613