Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
750
UXUS97 KBOU 091233
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0533 MST Sunday, November 9, 2025
This forecast is for Sunday, November 9, 2025:
If the trigger temperature of 45.1 F/7.3 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 424 ft/min (2.2 m/s)
Maximum height of thermals.................. 11028 ft MSL (5741 ft AGL)
Forecast maximum temperature................... 49.0 F/9.9 C
Time of trigger temperature.................... 1130 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................. 8546 ft MSL (3259 ft AGL)
Thermal soaring outlook for Monday 11/10....... Good
Wave Soaring Index............................. Good
Wave Soaring Index trend (to 1700 MST).........
Height of stable layer (12-18K ft MSL)......... 14620 ft MSL (9333 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 35006 ft MSL (29719 ft AGL)
Wave soaring outlook for Monday 11/10.......... Poor
Remarks...
Sunrise/Sunset.................... 06:37:55 / 16:48:41 MST
Total possible sunshine........... 10 hr 10 min 45 sec (610 min 45 sec)
Altitude of sun at 11:43:18 MST... 33.01 degrees
Upper air data from numerical model forecast valid on 11/09/2025 at 0500 MST
Freezing level.................. 5445 ft MSL (158 ft AGL)
Additional freezing level....... 6512 ft MSL (1225 ft AGL)
Convective condensation level... 18294 ft MSL (13007 ft AGL)
Lifted condensation level....... 13256 ft MSL (7969 ft AGL)
Lifted index.................... +13.4
K index......................... -13.8
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 -61.6 -78.9 325 57 30 0.3 0.2 M M M M M
45000 -61.1 -78.0 335 63 33 -0.2 -0.1 M M M M M
40000 -64.4 -83.9 345 96 50 -2.2 -1.2 M M M M M
38000 -61.6 -78.9 345 104 53 8.5 4.7 M M M M M
36000 -56.5 -69.7 345 108 55 8.5 4.7 M M M M M
34000 -51.4 -60.5 345 109 56 8.6 4.7 M M M M M
32000 -46.3 -51.3 345 105 54 8.6 4.7 M M M M M
30000 -41.3 -42.3 345 100 51 7.8 4.3 36.3 97.3 20.1 M M
29000 -39.0 -38.2 340 96 50 7.8 4.3 35.4 95.7 19.7 M M
28000 -36.1 -33.0 340 92 47 7.8 4.3 34.5 94.1 19.3 M M
27000 -33.7 -28.7 340 88 45 7.8 4.3 33.8 92.9 19.0 M M
26000 -31.4 -24.5 340 85 44 7.8 4.3 33.0 91.4 18.6 M M
25000 -29.0 -20.2 335 83 43 7.8 4.3 32.3 90.1 18.2 M M
24000 -26.8 -16.2 335 80 41 6.7 3.7 31.6 88.8 17.9 M M
23000 -24.8 -12.6 335 78 40 6.7 3.7 30.4 86.7 17.1 M M
22000 -22.8 -9.0 330 76 39 6.7 3.7 29.3 84.7 16.4 M M
21000 -21.0 -5.8 330 74 38 4.7 2.6 28.0 82.4 15.5 M M
20000 -19.6 -3.3 330 73 37 4.9 2.7 26.2 79.2 14.1 M M
19500 -18.9 -2.0 330 72 37 4.9 2.7 25.4 77.7 13.4 M M
19000 -18.1 -0.6 330 71 37 4.7 2.6 24.6 76.3 12.8 M M
18500 -17.3 0.9 330 71 36 7.5 4.1 24.0 75.1 12.3 M M
18000 -16.1 3.0 330 70 36 7.3 4.0 23.6 74.4 12.0 M M
17500 -15.0 5.0 330 70 36 6.5 3.6 23.2 73.7 11.8 M M
17000 -14.2 6.4 330 68 35 5.5 3.0 22.4 72.4 11.2 M M
16500 -13.3 8.1 330 66 34 5.5 3.0 21.7 71.1 10.7 M M
16000 -12.7 9.1 330 63 33 2.9 1.6 20.7 69.3 9.9 M M
15500 -12.2 10.0 330 60 31 3.2 1.8 19.6 67.3 9.0 M M
15000 -11.8 10.8 330 56 29 1.9 1.1 18.4 65.2 8.0 M M
14500 -11.5 11.3 325 52 27 1.8 1.0 17.1 62.8 6.8 M M
14000 -11.0 12.2 325 46 23 2.8 1.6 15.3 59.5 5.2 M M
13500 -10.7 12.7 325 41 21 2.8 1.5 14.1 57.4 4.1 M M
13000 -10.2 13.6 320 36 19 3.6 2.0 13.0 55.5 3.1 M M
12500 -9.7 14.5 320 32 17 3.6 1.9 12.0 53.7 2.2 M M
12000 -9.1 15.6 320 29 15 4.7 2.6 11.1 52.1 1.4 M M
11500 -8.4 16.9 325 25 13 4.7 2.6 10.3 50.6 0.6 M M
11000 -7.7 18.1 325 22 11 5.7 3.1 9.6 49.3 -0.1 417 2.1
10500 -6.8 19.8 330 19 10 5.5 3.0 9.0 48.1 -0.7 377 1.9
10250 -6.4 20.5 330 18 9 4.9 2.7 8.6 47.5 -1.1 358 1.8
10000 -6.1 21.0 330 18 9 5.1 2.8 8.2 46.8 -1.5 340 1.7
9750 -5.6 21.9 330 17 9 7.4 4.1 7.9 46.3 -1.7 319 1.6
9500 -5.0 23.0 335 15 8 7.3 4.0 7.8 46.0 -1.9 293 1.5
9250 -4.6 23.7 335 14 7 5.5 3.0 7.5 45.5 -2.2 273 1.4
9000 -4.2 24.4 335 13 7 5.3 2.9 7.2 44.9 -2.5 253 1.3
8750 -3.8 25.2 335 12 6 6.4 3.5 6.8 44.3 -2.8 233 1.2
8500 -3.3 26.1 330 11 5 5.5 3.0 6.6 43.9 -3.1 211 1.1
8250 -3.0 26.6 330 9 5 3.8 2.1 6.1 43.1 -3.5 195 1.0
8000 -2.7 27.1 325 7 4 4.0 2.2 5.7 42.3 -4.0 179 0.9
7750 -2.4 27.7 325 6 3 5.0 2.7 5.3 41.5 -4.4 163 0.8
7500 -2.0 28.4 315 4 2 6.2 3.4 5.0 41.0 -4.7 143 0.7
7250 -1.6 29.1 310 3 2 5.8 3.2 4.7 40.4 -5.0 123 0.6
7000 -1.1 30.0 295 2 1 6.1 3.3 4.4 39.9 -5.4 102 0.5
6750 -0.6 30.9 270 1 1 7.6 4.2 4.2 39.5 -5.6 80 0.4
6500 -0.0 32.0 270 1 0 8.4 4.6 4.1 39.3 -5.7 54 0.3
6250 0.6 33.1 000 0 0 9.0 4.9 4.0 39.1 -5.8 28 0.1
6000 1.2 34.2 000 0 0 4.1 2.2 3.8 38.9 -6.0 3 0.0
5750 1.1 34.0 210 1 1 -6.9 -3.8 3.0 37.3 -6.8 M M
5500 0.3 32.5 200 2 1 -12.0 -6.6 1.4 34.6 -8.4 15 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/09/2025 at 0800 MST | 11/09/2025 at 1100 MST
|
CAPE... 0.0 LI... +12.1 | CAPE... 0.0 LI... +12.7
CINH... 0.0 K Index... -10.7 | CINH... 0.0 K Index... -6.3
|
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 -63.0 -81.4 335 62 32 -1.1 -0.6 | -65.1 -85.2 335 69 36 -2.1 -1.1
45000 -64.6 -84.3 345 74 38 -0.9 -0.5 | -68.2 -90.8 340 91 47 -0.2 -0.1
40000 -65.6 -86.1 340 93 48 -0.5 -0.3 | -65.5 -85.9 345 95 49 2.0 1.1
38000 -61.7 -79.1 340 97 50 9.7 5.3 | -61.0 -77.8 340 95 49 9.6 5.3
36000 -55.9 -68.6 345 99 51 9.7 5.3 | -55.2 -67.4 340 94 48 9.6 5.3
34000 -50.5 -58.9 345 100 51 8.0 4.4 | -49.9 -57.8 340 91 47 7.9 4.3
32000 -45.7 -50.3 345 95 49 8.0 4.4 | -45.1 -49.2 345 87 45 7.9 4.3
30000 -41.0 -41.8 345 91 47 7.2 4.0 | -40.6 -41.1 345 81 42 7.2 3.9
29000 -38.3 -36.9 340 88 45 7.2 4.0 | -38.4 -37.1 350 76 39 7.2 3.9
28000 -36.2 -33.2 340 85 44 7.2 4.0 | -35.7 -32.3 350 70 36 7.2 4.0
27000 -33.8 -28.8 340 84 43 8.8 4.8 | -33.4 -28.1 345 68 35 8.3 4.6
26000 -31.2 -24.2 335 83 43 8.8 4.8 | -30.9 -23.6 345 68 35 8.4 4.6
25000 -28.6 -19.5 335 82 42 8.8 4.8 | -28.4 -19.1 340 68 35 8.4 4.6
24000 -26.0 -14.8 335 81 42 7.5 4.1 | -25.9 -14.6 340 69 35 8.2 4.5
23000 -23.8 -10.8 335 80 41 7.7 4.2 | -23.5 -10.3 340 71 36 8.3 4.5
22000 -21.5 -6.7 335 79 40 7.6 4.2 | -21.0 -5.8 335 72 37 8.2 4.5
21000 -19.5 -3.1 335 76 39 5.2 2.8 | -18.8 -1.8 335 73 38 6.6 3.6
20000 -17.9 -0.2 330 73 38 5.3 2.9 | -16.8 1.8 335 72 37 6.6 3.6
19500 -17.1 1.2 330 71 37 5.3 2.9 | -15.9 3.4 340 71 37 6.6 3.6
19000 -16.3 2.7 330 70 36 5.5 3.0 | -14.9 5.2 340 71 36 6.5 3.5
18500 -15.7 3.7 330 68 35 3.4 1.9 | -14.2 6.4 340 69 36 4.2 2.3
18000 -15.2 4.6 330 67 34 3.7 2.0 | -13.5 7.7 340 67 34 4.4 2.4
17500 -14.6 5.7 330 65 33 4.7 2.6 | -12.9 8.8 340 65 33 2.4 1.3
17000 -13.8 7.2 335 64 33 5.3 2.9 | -12.7 9.1 340 61 32 1.9 1.0
16500 -13.0 8.6 335 62 32 5.1 2.8 | -12.4 9.7 335 58 30 2.5 1.4
16000 -12.4 9.7 335 60 31 3.5 1.9 | -11.9 10.6 335 56 29 4.4 2.4
15500 -11.8 10.8 335 57 30 3.7 2.1 | -11.2 11.8 340 53 27 4.4 2.4
15000 -11.3 11.7 335 55 28 3.1 1.7 | -10.5 13.1 340 50 26 3.6 2.0
14500 -10.5 13.1 335 51 26 3.1 1.7 | -9.9 14.2 335 48 25 3.8 2.1
14000 -10.1 13.8 335 48 25 2.9 1.6 | -9.2 15.4 335 44 23 3.0 1.6
13500 -9.7 14.5 330 45 23 2.9 1.6 | -8.7 16.3 335 41 21 3.0 1.7
13000 -9.3 15.3 330 40 21 2.4 1.3 | -8.2 17.2 335 39 20 3.3 1.8
12500 -9.0 15.8 325 36 18 2.5 1.4 | -7.7 18.1 335 37 19 3.4 1.9
12000 -8.7 16.3 325 31 16 2.2 1.2 | -7.2 19.0 330 33 17 3.7 2.0
11500 -8.4 16.9 325 26 13 2.4 1.3 | -6.7 19.9 330 29 15 3.6 2.0
11000 -7.9 17.8 325 22 11 3.8 2.1 | -6.3 20.7 325 25 13 3.2 1.8
10500 -7.4 18.7 330 18 9 4.6 2.5 | -5.8 21.6 325 20 10 3.8 2.1
10250 -6.9 19.6 330 17 9 7.0 3.8 | -5.5 22.1 325 18 10 5.1 2.8
10000 -6.4 20.5 330 16 8 7.3 4.0 | -5.1 22.8 325 17 9 4.8 2.7
9750 -6.0 21.2 335 15 8 2.5 1.4 | -4.9 23.2 325 15 8 1.8 1.0
9500 -5.9 21.4 340 13 7 3.7 2.0 | -4.8 23.4 325 12 6 3.1 1.7
9250 -5.4 22.3 340 12 6 7.7 4.2 | -4.4 24.1 325 11 6 5.8 3.2
9000 -4.8 23.4 340 11 6 7.3 4.0 | -4.0 24.8 325 10 5 5.2 2.8
8750 -4.3 24.3 345 10 5 5.4 2.9 | -3.6 25.5 325 8 4 4.6 2.5
8500 -4.0 24.8 350 9 4 5.2 2.9 | -3.3 26.1 325 6 3 4.5 2.5
8250 -3.5 25.7 350 8 4 7.2 3.9 | -2.9 26.8 330 4 2 5.4 3.0
8000 -3.0 26.6 355 7 3 7.2 3.9 | -2.5 27.5 345 2 1 4.6 2.5
7750 -2.5 27.5 360 6 3 5.2 2.9 | -2.2 28.0 085 1 1 6.4 3.5
7500 -2.2 28.0 360 4 2 5.2 2.8 | -1.6 29.1 090 1 1 9.1 5.0
7250 -1.7 28.9 005 3 2 7.6 4.2 | -0.9 30.4 105 2 1 9.3 5.1
7000 -1.2 29.8 010 2 1 6.1 3.4 | -0.2 31.6 110 2 1 8.9 4.9
6750 -0.7 30.7 020 1 1 6.4 3.5 | 0.4 32.7 110 2 1 9.5 5.2
6500 -0.2 31.6 035 1 0 7.9 4.3 | 1.2 34.2 110 2 1 10.5 5.7
6250 0.4 32.7 065 1 0 7.5 4.1 | 2.0 35.6 110 2 1 10.4 5.7
6000 0.9 33.6 110 1 0 4.3 2.3 | 2.8 37.0 110 2 1 11.9 6.5
5750 1.1 34.0 175 1 0 1.3 0.7 | 3.7 38.7 110 2 1 10.0 5.5
5500 1.2 34.2 200 1 1 2.2 1.2 | 4.3 39.7 110 2 1 10.6 5.8
11/09/2025 at 1400 MST | 11/09/2025 at 1700 MST
|
CAPE... 0.0 LI... +11.3 | CAPE... 0.0 LI... +10.2
CINH... 0.0 K Index... -0.9 | CINH... 0.0 K Index... +1.8
|
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 -65.3 -85.5 335 77 39 -2.0 -1.1 | -65.9 -86.6 335 74 38 -2.0 -1.1
45000 -68.2 -90.8 340 98 50 3.1 1.7 | -68.5 -91.3 340 93 48 4.1 2.2
40000 -64.3 -83.7 335 78 40 2.7 1.5 | -63.1 -81.6 340 94 48 3.6 2.0
38000 -60.0 -76.0 340 77 40 8.6 4.7 | -59.3 -74.7 340 88 45 7.2 3.9
36000 -54.8 -66.6 340 79 41 8.6 4.7 | -55.0 -67.0 340 81 42 7.2 3.9
34000 -49.7 -57.5 340 80 41 8.4 4.6 | -50.3 -58.5 345 77 39 8.5 4.6
32000 -44.6 -48.3 340 80 41 8.4 4.6 | -45.2 -49.4 345 75 38 8.5 4.6
30000 -39.3 -38.7 345 77 40 7.4 4.1 | -39.5 -39.1 345 72 37 8.5 4.7
29000 -37.0 -34.6 345 74 38 7.4 4.1 | -37.0 -34.6 345 70 36 8.5 4.7
28000 -34.8 -30.6 345 72 37 7.4 4.1 | -34.4 -29.9 345 69 36 8.5 4.7
27000 -32.5 -26.5 345 69 35 7.9 4.3 | -32.0 -25.6 345 67 35 7.9 4.4
26000 -30.2 -22.4 345 66 34 7.9 4.3 | -29.6 -21.3 345 65 33 7.9 4.3
25000 -27.8 -18.0 340 64 33 7.9 4.3 | -27.2 -17.0 340 63 32 7.9 4.3
24000 -25.5 -13.9 340 63 32 7.4 4.1 | -24.9 -12.8 340 61 32 7.4 4.1
23000 -23.2 -9.8 340 64 33 7.5 4.1 | -22.7 -8.9 340 61 31 7.4 4.1
22000 -21.0 -5.8 340 64 33 7.5 4.1 | -20.5 -4.9 340 60 31 7.4 4.1
21000 -18.9 -2.0 340 65 34 6.5 3.5 | -18.4 -1.1 340 60 31 6.4 3.5
20000 -17.0 1.4 340 66 34 6.5 3.5 | -16.5 2.3 345 60 31 6.4 3.5
19500 -16.1 3.0 340 66 34 6.5 3.6 | -15.6 3.9 345 60 31 6.4 3.5
19000 -15.1 4.8 340 67 34 6.6 3.6 | -14.6 5.7 345 60 31 6.8 3.7
18500 -14.1 6.6 340 66 34 7.0 3.8 | -13.5 7.7 345 60 31 7.9 4.3
18000 -13.1 8.4 340 64 33 7.1 3.9 | -12.4 9.7 345 59 30 8.1 4.4
17500 -12.2 10.0 340 62 32 3.0 1.7 | -11.4 11.5 345 58 30 4.4 2.4
17000 -12.0 10.4 340 60 31 2.0 1.1 | -10.8 12.6 345 56 29 4.0 2.2
16500 -11.7 10.9 340 58 30 2.3 1.2 | -10.2 13.6 345 55 28 3.2 1.8
16000 -11.3 11.7 340 55 28 3.0 1.6 | -9.9 14.2 345 53 27 2.1 1.1
15500 -10.6 12.9 340 51 26 3.8 2.1 | -9.6 14.7 345 52 27 2.2 1.2
15000 -9.9 14.2 340 49 25 4.4 2.4 | -9.2 15.4 340 49 25 3.7 2.0
14500 -9.2 15.4 335 46 24 4.1 2.3 | -8.4 16.9 340 46 24 4.0 2.2
14000 -8.6 16.5 335 44 22 3.4 1.9 | -7.7 18.1 340 44 22 4.5 2.5
13500 -8.1 17.4 335 41 21 3.6 2.0 | -7.0 19.4 335 41 21 4.4 2.4
13000 -7.5 18.5 335 39 20 4.3 2.3 | -6.3 20.7 330 38 20 4.2 2.3
12500 -6.8 19.8 330 37 19 4.2 2.3 | -5.7 21.7 330 35 18 4.4 2.4
12000 -6.2 20.8 330 33 17 4.4 2.4 | -5.0 23.0 325 31 16 5.3 2.9
11500 -5.6 21.9 325 29 15 4.6 2.5 | -4.2 24.4 315 26 14 5.5 3.0
11000 -4.9 23.2 320 24 12 5.4 2.9 | -3.3 26.1 315 23 12 6.1 3.4
10500 -4.1 24.6 320 20 10 5.5 3.0 | -2.4 27.7 310 19 10 5.7 3.1
10250 -3.7 25.3 315 18 9 6.1 3.4 | -2.0 28.4 310 18 9 4.7 2.6
10000 -3.2 26.2 315 17 9 5.6 3.1 | -1.7 28.9 310 18 9 5.4 3.0
9750 -2.9 26.8 315 15 8 4.5 2.5 | -1.2 29.8 305 16 8 7.4 4.1
9500 -2.6 27.3 315 14 7 3.5 1.9 | -0.7 30.7 305 15 8 4.8 2.6
9250 -2.3 27.9 320 12 6 3.1 1.7 | -0.5 31.1 305 14 7 1.9 1.0
9000 -2.1 28.2 320 10 5 3.1 1.7 | -0.3 31.5 305 13 7 2.8 1.5
8750 -1.9 28.6 325 8 4 3.1 1.7 | -0.1 31.8 300 11 6 3.3 1.8
8500 -1.6 29.1 330 5 3 4.1 2.2 | 0.1 32.2 300 9 5 2.8 1.6
8250 -1.3 29.7 335 4 2 5.1 2.8 | 0.3 32.5 290 7 4 2.3 1.3
8000 -0.9 30.4 350 2 1 3.7 2.1 | 0.5 32.9 275 5 3 1.8 1.0
7750 -0.6 30.9 035 2 1 8.2 4.5 | 0.7 33.3 245 4 2 4.3 2.3
7500 0.2 32.4 040 2 1 11.5 6.3 | 1.1 34.0 250 3 1 7.5 4.1
7250 1.0 33.8 040 2 1 10.0 5.5 | 1.7 35.1 230 2 1 7.8 4.3
7000 1.7 35.1 045 2 1 9.2 5.0 | 2.3 36.1 190 2 1 6.7 3.7
6750 2.4 36.3 045 2 1 9.2 5.0 | 2.8 37.0 165 2 1 8.2 4.5
6500 3.2 37.8 040 2 1 10.8 5.9 | 3.5 38.3 140 1 1 10.9 6.0
6250 4.0 39.2 040 2 1 10.8 5.9 | 4.3 39.7 115 2 1 10.4 5.7
6000 4.8 40.6 040 2 1 10.2 5.6 | 5.1 41.2 100 2 1 9.8 5.4
5750 5.6 42.1 040 2 1 13.5 7.4 | 5.8 42.4 090 2 1 8.6 4.7
5500 6.9 44.4 040 2 1 21.1 11.6 | 6.3 43.3 085 2 1 6.9 3.8
________________________________________________________________________________
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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