Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
316
UXUS97 KBOU 081224
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0516 MST Saturday, November 8, 2025
This forecast is for Saturday, November 8, 2025:
If the trigger temperature of 52.8 F/11.6 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 434 ft/min (2.2 m/s)
Maximum height of thermals.................. 11004 ft MSL (5741 ft AGL)
Forecast maximum temperature................... 56.0 F/13.8 C
Time of trigger temperature.................... 1145 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................. 7862 ft MSL (2598 ft AGL)
Thermal soaring outlook for Sunday 11/09....... Poor
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1700 MST).........
Height of stable layer (12-18K ft MSL)......... 17056 ft MSL (11793 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Weak PVA
Potential height of wave....................... 17793 ft MSL (12530 ft AGL)
Wave soaring outlook for Sunday 11/09.......... Poor
Remarks...
Sunrise/Sunset.................... 06:36:47 / 16:49:39 MST
Total possible sunshine........... 10 hr 12 min 52 sec (612 min 52 sec)
Altitude of sun at 11:43:13 MST... 33.29 degrees
Upper air data from numerical model forecast valid on 11/08/2025 at 0500 MST
Freezing level.................. 9093 ft MSL (3830 ft AGL)
Convective condensation level... 13496 ft MSL (8233 ft AGL)
Lifted condensation level....... 12589 ft MSL (7325 ft AGL)
Lifted index.................... +7.3
K index......................... +7.6
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 -60.6 -77.1 300 63 33 0.9 0.5 M M M M M
45000 -59.4 -74.9 295 74 38 0.5 0.3 M M M M M
40000 -62.8 -81.0 295 96 49 -2.4 -1.3 M M M M M
38000 -60.5 -76.9 295 100 51 8.4 4.6 M M M M M
36000 -55.5 -67.9 295 100 51 8.4 4.6 M M M M M
34000 -50.6 -59.1 295 100 51 7.3 4.0 M M M M M
32000 -46.2 -51.2 300 97 50 7.3 4.0 M M M M M
30000 -41.8 -43.2 300 93 48 7.5 4.1 35.1 95.2 16.4 M M
29000 -39.6 -39.3 305 90 46 7.5 4.1 34.1 93.4 15.8 M M
28000 -37.3 -35.1 305 87 45 7.5 4.1 33.3 91.9 15.4 M M
27000 -34.5 -30.1 305 83 43 7.8 4.3 32.4 90.2 14.9 M M
26000 -32.2 -26.0 305 79 41 7.8 4.3 31.5 88.7 14.4 M M
25000 -29.8 -21.6 300 75 39 7.8 4.3 30.8 87.4 14.0 M M
24000 -27.5 -17.5 300 71 37 8.2 4.5 30.2 86.4 13.6 M M
23000 -25.0 -13.0 300 68 35 8.5 4.6 29.6 85.3 13.3 M M
22000 -22.4 -8.3 300 65 34 8.5 4.6 29.2 84.5 13.1 M M
21000 -20.0 -4.0 300 62 32 6.2 3.4 28.6 83.5 12.8 M M
20000 -18.3 -0.9 305 61 32 5.8 3.2 27.2 80.9 11.7 M M
19500 -17.4 0.7 305 61 31 5.8 3.2 26.5 79.6 11.2 M M
19000 -16.6 2.1 305 60 31 5.7 3.1 25.8 78.4 10.7 M M
18500 -15.7 3.7 305 60 31 5.0 2.8 25.2 77.3 10.2 M M
18000 -15.1 4.8 305 61 31 4.4 2.4 24.2 75.6 9.4 M M
17500 -14.4 6.1 305 62 32 4.5 2.5 23.3 73.9 8.6 M M
17000 -13.9 7.0 305 61 31 2.4 1.3 22.2 71.9 7.7 M M
16500 -13.6 7.5 305 57 29 2.6 1.4 21.0 69.8 6.6 M M
16000 -13.1 8.4 305 53 27 4.5 2.5 19.9 67.8 5.7 M M
15500 -12.4 9.7 305 52 27 5.1 2.8 19.1 66.3 5.0 M M
15000 -11.6 11.1 305 50 26 5.3 2.9 18.3 65.0 4.3 M M
14500 -10.8 12.6 305 50 26 5.6 3.1 17.6 63.7 3.6 M M
14000 -10.0 14.0 305 49 25 5.7 3.1 16.9 62.4 3.0 M M
13500 -9.1 15.6 305 49 25 6.5 3.5 16.3 61.4 2.4 M M
13000 -7.7 18.1 305 49 25 6.6 3.6 15.5 59.9 1.7 M M
12500 -6.8 19.8 300 48 25 6.7 3.7 15.0 59.0 1.2 M M
12000 -5.8 21.6 300 47 24 7.1 3.9 14.5 58.2 0.7 M M
11500 -4.7 23.5 300 47 24 7.3 4.0 14.1 57.5 0.3 M M
11000 -3.7 25.3 300 46 24 7.0 3.9 13.8 56.8 -0.1 426 2.2
10500 -2.7 27.1 305 44 22 7.8 4.3 13.3 55.9 -0.6 382 1.9
10250 -2.2 28.0 305 42 22 3.0 1.7 13.0 55.5 -0.8 359 1.8
10000 -2.1 28.2 305 42 21 4.2 2.3 12.4 54.3 -1.4 349 1.8
9750 -1.5 29.3 305 40 20 9.7 5.3 12.3 54.1 -1.5 323 1.6
9500 -0.8 30.6 305 37 19 8.5 4.7 12.2 53.9 -1.6 297 1.5
9250 -0.2 31.6 305 35 18 7.7 4.2 12.1 53.8 -1.7 271 1.4
9000 0.3 32.5 305 33 17 6.1 3.4 11.9 53.3 -2.0 248 1.3
8750 0.8 33.4 305 32 16 6.8 3.7 11.6 52.9 -2.2 227 1.2
8500 1.3 34.3 310 29 15 7.3 4.0 11.4 52.5 -2.4 204 1.0
8250 1.8 35.2 310 27 14 6.8 3.7 11.2 52.2 -2.6 180 0.9
8000 2.3 36.1 315 25 13 6.3 3.5 10.9 51.7 -2.9 159 0.8
7750 2.8 37.0 320 23 12 7.2 3.9 10.7 51.3 -3.1 136 0.7
7500 3.4 38.1 325 21 11 7.6 4.2 10.5 51.0 -3.3 112 0.6
7250 3.9 39.0 330 20 10 7.4 4.0 10.4 50.6 -3.5 88 0.4
7000 4.5 40.1 335 19 10 7.1 3.9 10.2 50.3 -3.7 64 0.3
6750 5.0 41.0 340 18 9 8.3 4.5 10.0 50.0 -3.9 41 0.2
6500 5.6 42.1 345 17 9 5.9 3.2 9.9 49.7 -4.0 16 0.1
6250 5.9 42.6 350 15 8 2.5 1.4 9.4 48.9 -4.5 0 0.0
6000 6.1 43.0 360 14 7 4.7 2.6 8.9 48.0 -5.0 M M
5750 6.4 43.5 005 13 7 -0.9 -0.5 8.4 47.2 -5.5 M M
5500 5.7 42.3 015 9 4 -19.1 -10.5 7.0 44.6 -6.9 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/08/2025 at 0800 MST | 11/08/2025 at 1100 MST
|
CAPE... 0.0 LI... +8.5 | CAPE... 0.0 LI... +9.2
CINH... 0.0 K Index... -6.3 | CINH... 0.0 K Index... -16.8
|
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 -60.9 -77.6 300 63 32 1.4 0.7 | -60.1 -76.2 295 50 26 1.6 0.9
45000 -58.8 -73.8 295 60 31 0.9 0.5 | -57.7 -71.9 295 62 32 1.4 0.8
40000 -62.0 -79.6 295 84 43 -2.1 -1.2 | -62.2 -80.0 295 91 47 -3.0 -1.6
38000 -60.0 -76.0 295 91 47 7.3 4.0 | -60.8 -77.4 295 96 50 6.7 3.7
36000 -55.6 -68.1 295 95 49 7.3 4.0 | -56.7 -70.1 295 97 50 6.8 3.7
34000 -51.2 -60.2 295 97 50 7.4 4.0 | -52.5 -62.5 295 96 50 7.9 4.3
32000 -46.8 -52.2 300 93 48 7.4 4.0 | -47.8 -54.0 295 91 47 7.9 4.3
30000 -42.4 -44.3 300 89 46 7.5 4.1 | -43.2 -45.8 300 87 45 7.6 4.2
29000 -39.5 -39.1 300 85 44 7.6 4.1 | -40.9 -41.6 300 85 44 7.6 4.2
28000 -37.3 -35.1 300 82 42 7.6 4.1 | -38.0 -36.4 300 83 43 7.6 4.2
27000 -35.0 -31.0 300 80 41 8.0 4.4 | -35.7 -32.3 300 82 42 8.5 4.7
26000 -32.6 -26.7 300 79 41 8.0 4.4 | -33.1 -27.6 300 80 41 8.6 4.7
25000 -30.2 -22.4 300 78 40 8.0 4.4 | -30.5 -22.9 305 79 41 8.6 4.7
24000 -27.8 -18.0 300 77 40 8.0 4.4 | -27.9 -18.2 305 78 40 8.1 4.5
23000 -25.4 -13.7 300 76 39 7.9 4.4 | -25.6 -14.1 305 76 39 7.7 4.2
22000 -23.0 -9.4 305 75 39 8.0 4.4 | -23.4 -10.1 305 75 39 7.7 4.2
21000 -20.7 -5.3 305 74 38 6.9 3.8 | -21.1 -6.0 305 73 38 6.6 3.6
20000 -18.7 -1.7 305 72 37 6.7 3.7 | -19.2 -2.6 305 71 36 6.4 3.5
19500 -17.7 0.1 305 71 37 6.7 3.7 | -18.3 -0.9 310 69 36 6.4 3.5
19000 -16.7 1.9 310 71 36 6.6 3.6 | -17.3 0.9 310 68 35 6.4 3.5
18500 -15.7 3.7 310 70 36 5.8 3.2 | -16.3 2.7 310 67 34 5.6 3.0
18000 -15.0 5.0 310 67 34 4.9 2.7 | -15.6 3.9 310 64 33 4.9 2.7
17500 -14.3 6.3 305 64 33 4.9 2.7 | -14.9 5.2 310 62 32 4.9 2.7
17000 -13.6 7.5 305 61 31 4.1 2.2 | -14.1 6.6 310 60 31 4.8 2.6
16500 -13.0 8.6 305 57 29 4.2 2.3 | -13.4 7.9 310 59 31 4.8 2.7
16000 -12.4 9.7 305 53 27 3.3 1.8 | -12.7 9.1 310 58 30 3.8 2.1
15500 -11.9 10.6 305 49 25 3.1 1.7 | -12.2 10.0 310 54 28 3.6 2.0
15000 -11.2 11.8 300 43 22 3.8 2.1 | -11.3 11.7 310 49 25 5.2 2.8
14500 -10.7 12.7 300 41 21 3.8 2.1 | -10.6 12.9 310 48 25 5.1 2.8
14000 -10.1 13.8 300 40 20 5.1 2.8 | -9.9 14.2 310 46 24 4.0 2.2
13500 -9.3 15.3 300 42 21 5.4 3.0 | -9.3 15.3 310 44 22 3.8 2.1
13000 -8.5 16.7 300 43 22 4.4 2.4 | -8.7 16.3 310 41 21 4.8 2.6
12500 -8.0 17.6 300 43 22 3.9 2.2 | -8.0 17.6 310 39 20 5.1 2.8
12000 -7.5 18.5 300 43 22 5.7 3.2 | -7.3 18.9 310 36 19 5.6 3.1
11500 -6.5 20.3 300 42 21 6.8 3.8 | -6.4 20.5 305 34 17 5.8 3.2
11000 -5.5 22.1 305 40 21 5.8 3.2 | -5.6 21.9 305 31 16 5.3 2.9
10500 -4.8 23.4 305 36 19 5.7 3.1 | -4.9 23.2 305 29 15 5.5 3.0
10250 -4.4 24.1 305 35 18 3.7 2.0 | -4.6 23.7 305 28 14 3.7 2.0
10000 -4.2 24.4 305 34 17 4.0 2.2 | -4.4 24.1 305 27 14 3.7 2.0
9750 -3.7 25.3 305 31 16 7.4 4.1 | -4.0 24.8 305 25 13 6.5 3.5
9500 -3.2 26.2 305 29 15 8.3 4.6 | -3.5 25.7 310 23 12 7.1 3.9
9250 -2.6 27.3 305 26 13 6.8 3.7 | -3.1 26.4 310 20 10 5.9 3.3
9000 -2.2 28.0 305 24 12 5.1 2.8 | -2.7 27.1 315 18 9 4.9 2.7
8750 -1.8 28.8 305 21 11 6.6 3.6 | -2.3 27.9 315 16 8 6.2 3.4
8500 -1.2 29.8 310 19 10 7.7 4.2 | -1.8 28.8 315 14 7 6.8 3.7
8250 -0.7 30.7 315 17 9 7.0 3.8 | -1.4 29.5 320 12 6 5.5 3.0
8000 -0.2 31.6 320 16 8 6.5 3.6 | -1.0 30.2 330 9 5 4.6 2.5
7750 0.3 32.5 330 16 8 6.9 3.8 | -0.7 30.7 340 8 4 6.1 3.4
7500 0.8 33.4 340 16 8 6.2 3.4 | -0.1 31.8 355 6 3 8.4 4.6
7250 1.2 34.2 345 17 9 4.6 2.5 | 0.5 32.9 360 6 3 9.5 5.2
7000 1.5 34.7 355 18 9 4.6 2.5 | 1.3 34.3 005 6 3 9.7 5.3
6750 1.8 35.2 005 19 10 3.5 1.9 | 2.0 35.6 010 5 3 9.6 5.3
6500 2.0 35.6 010 20 10 2.2 1.2 | 2.7 36.9 010 5 3 9.8 5.4
6250 2.2 36.0 015 17 9 2.7 1.5 | 3.4 38.1 010 5 3 10.4 5.7
6000 2.4 36.3 020 15 8 2.2 1.2 | 4.2 39.6 010 5 3 8.8 4.8
5750 2.6 36.7 035 13 6 3.7 2.1 | 4.9 40.8 010 5 2 14.7 8.1
5500 3.0 37.4 040 9 4 8.6 4.7 | 6.6 43.9 010 5 2 27.9 15.3
11/08/2025 at 1400 MST | 11/08/2025 at 1700 MST
|
CAPE... 0.0 LI... +8.2 | CAPE... 0.0 LI... +6.9
CINH... 0.0 K Index... -15.2 | CINH... 0.0 K Index... -2.6
|
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 -59.9 -75.8 300 62 32 1.4 0.8 | -60.0 -76.0 300 67 34 1.3 0.7
45000 -57.8 -72.0 300 77 40 1.6 0.9 | -58.1 -72.6 300 85 44 1.3 0.7
40000 -60.0 -76.0 305 86 44 -1.5 -0.8 | -57.5 -71.5 325 90 46 0.4 0.2
38000 -59.2 -74.6 305 88 45 3.8 2.1 | -56.8 -70.2 325 94 48 1.9 1.1
36000 -56.9 -70.4 300 89 46 3.8 2.1 | -55.6 -68.1 320 97 50 1.9 1.1
34000 -54.1 -65.4 300 89 46 9.0 4.9 | -54.1 -65.4 315 99 51 7.7 4.2
32000 -48.9 -56.0 300 81 42 8.7 4.8 | -49.8 -57.6 315 91 47 7.1 3.9
30000 -43.7 -46.7 300 75 39 8.3 4.5 | -45.3 -49.5 315 84 43 9.2 5.1
29000 -40.6 -41.1 300 78 40 8.3 4.6 | -41.9 -43.4 310 84 43 9.1 5.0
28000 -38.1 -36.6 300 81 42 8.3 4.6 | -39.2 -38.6 310 84 43 9.1 5.0
27000 -35.6 -32.1 305 83 43 8.4 4.6 | -36.6 -33.9 305 84 43 7.6 4.2
26000 -33.1 -27.6 305 82 42 8.4 4.6 | -34.5 -30.1 310 83 43 6.9 3.8
25000 -30.6 -23.1 305 81 42 8.4 4.6 | -32.4 -26.3 310 82 42 6.9 3.8
24000 -28.1 -18.6 305 80 41 7.9 4.3 | -30.4 -22.7 315 81 42 7.4 4.0
23000 -25.9 -14.6 305 78 40 7.4 4.0 | -27.9 -18.2 310 78 40 8.2 4.5
22000 -23.7 -10.7 305 75 39 7.4 4.0 | -25.5 -13.9 310 74 38 8.2 4.5
21000 -21.5 -6.7 310 73 38 6.6 3.6 | -23.1 -9.6 310 71 37 6.3 3.4
20000 -19.6 -3.3 310 71 37 6.4 3.5 | -21.4 -6.5 310 70 36 5.7 3.1
19500 -18.7 -1.7 310 71 36 6.4 3.5 | -20.6 -5.1 310 70 36 5.7 3.1
19000 -17.7 0.1 315 70 36 6.4 3.5 | -19.7 -3.5 310 70 36 5.6 3.1
18500 -16.7 1.9 315 69 35 5.9 3.2 | -18.9 -2.0 315 69 36 5.3 2.9
18000 -15.9 3.4 315 66 34 5.6 3.0 | -18.1 -0.6 310 64 33 5.0 2.8
17500 -15.0 5.0 315 64 33 5.6 3.1 | -17.4 0.7 310 59 30 5.1 2.8
17000 -14.3 6.3 315 61 31 4.7 2.6 | -16.7 1.9 310 56 29 3.6 2.0
16500 -13.6 7.5 310 58 30 4.9 2.7 | -16.2 2.8 310 54 28 3.8 2.1
16000 -12.9 8.8 310 55 29 3.3 1.8 | -15.4 4.3 310 48 25 3.3 1.8
15500 -12.5 9.5 310 52 27 2.9 1.6 | -14.9 5.2 305 44 22 3.1 1.7
15000 -12.0 10.4 310 49 25 3.0 1.7 | -14.3 6.3 305 39 20 5.3 2.9
14500 -11.4 11.5 310 44 23 3.1 1.7 | -13.6 7.5 305 36 18 5.0 2.7
14000 -10.8 12.6 310 41 21 4.4 2.4 | -12.7 9.1 300 32 17 6.8 3.7
13500 -10.2 13.6 305 38 20 4.5 2.5 | -11.7 10.9 300 29 15 6.9 3.8
13000 -9.5 14.9 305 35 18 5.6 3.0 | -10.7 12.7 300 26 13 6.7 3.7
12500 -8.6 16.5 305 33 17 5.9 3.2 | -9.8 14.4 300 22 11 6.7 3.7
12000 -7.8 18.0 305 30 15 5.9 3.3 | -8.9 16.0 305 18 9 6.0 3.3
11500 -7.0 19.4 305 25 13 6.0 3.3 | -8.0 17.6 310 14 7 5.8 3.2
11000 -6.1 21.0 310 21 11 6.0 3.3 | -7.1 19.2 325 11 6 7.7 4.2
10500 -5.3 22.5 315 16 8 6.7 3.7 | -5.9 21.4 330 10 5 8.6 4.7
10250 -4.8 23.4 320 13 7 3.2 1.8 | -5.3 22.5 335 10 5 5.2 2.9
10000 -4.7 23.5 325 12 6 3.4 1.9 | -5.0 23.0 340 10 5 5.8 3.2
9750 -4.2 24.4 330 11 5 8.2 4.5 | -4.3 24.3 345 10 5 10.6 5.8
9500 -3.6 25.5 335 9 4 8.3 4.6 | -3.6 25.5 355 10 5 10.7 5.9
9250 -3.1 26.4 345 7 4 7.6 4.1 | -2.8 27.0 360 10 5 8.9 4.9
9000 -2.5 27.5 350 6 3 7.4 4.1 | -2.2 28.0 005 10 5 7.7 4.2
8750 -1.9 28.6 350 6 3 9.7 5.3 | -1.6 29.1 005 11 5 9.7 5.3
8500 -1.1 30.0 355 6 3 10.5 5.8 | -0.8 30.6 010 11 6 10.2 5.6
8250 -0.4 31.3 355 6 3 9.6 5.3 | -0.1 31.8 010 11 6 10.0 5.5
8000 0.3 32.5 355 6 3 9.2 5.1 | 0.7 33.3 010 11 6 10.1 5.5
7750 1.0 33.8 355 6 3 10.4 5.7 | 1.4 34.5 015 12 6 9.7 5.3
7500 1.8 35.2 355 5 3 10.5 5.8 | 2.1 35.8 015 12 6 10.1 5.5
7250 2.6 36.7 355 5 3 9.7 5.3 | 2.9 37.2 015 12 6 10.6 5.8
7000 3.3 37.9 355 5 3 9.6 5.2 | 3.7 38.7 015 12 6 11.0 6.1
6750 4.0 39.2 355 5 3 10.6 5.8 | 4.5 40.1 015 12 6 8.6 4.7
6500 4.9 40.8 355 5 3 10.7 5.9 | 5.0 41.0 015 12 6 8.3 4.5
6250 5.6 42.1 355 5 3 9.9 5.4 | 5.8 42.4 020 12 6 10.3 5.7
6000 6.4 43.5 355 5 3 9.6 5.3 | 6.5 43.7 020 12 6 10.2 5.6
5750 7.2 45.0 355 5 3 13.7 7.5 | 7.2 45.0 020 11 6 7.2 3.9
5500 8.5 47.3 355 5 2 22.1 12.1 | 7.5 45.5 020 8 4 0.2 0.1
________________________________________________________________________________
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