Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
930
UXUS97 KBOU 160031
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1831 MDT Wednesday, October 15, 2025
This forecast is for Thursday, October 16, 2025:
If the trigger temperature of 68.1 F/20.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 441 ft/min (2.2 m/s)
Maximum height of thermals.................. 10776 ft MSL (5484 ft AGL)
Forecast maximum temperature................... 69.0 F/21.0 C
Time of trigger temperature.................... 1545 MDT
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................. 5995 ft MSL (702 ft AGL)
Thermal soaring outlook for Friday 10/17....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Slight increase
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 15614 ft MSL (10322 ft AGL)
Wave soaring outlook for Friday 10/17.......... Poor
Remarks... Breezy westerly winds Thursday afternoon
Sunrise/Sunset.................... 07:11:25 / 18:18:23 MDT
Total possible sunshine........... 11 hr 6 min 58 sec (666 min 58 sec)
Altitude of sun at 12:44:54 MDT... 40.92 degrees
Upper air data from numerical model forecast valid on 10/16/2025 at 0600 MDT
Freezing level.................. 12592 ft MSL (7300 ft AGL)
Convective condensation level... 13863 ft MSL (8571 ft AGL)
Lifted condensation level....... 12918 ft MSL (7626 ft AGL)
Lifted index.................... +3.3
K index......................... +6.0
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 -63.2 -81.8 220 44 22 0.9 0.5 M M M M M
45000 -61.1 -78.0 220 79 41 4.4 2.4 M M M M M
40000 -54.2 -65.6 210 86 44 5.1 2.8 M M M M M
38000 -50.1 -58.2 210 87 45 7.0 3.8 M M M M M
36000 -45.9 -50.6 205 87 45 7.0 3.8 M M M M M
34000 -41.8 -43.2 205 88 45 6.8 3.8 M M M M M
32000 -37.7 -35.9 200 90 46 6.8 3.8 M M M M M
30000 -33.5 -28.3 200 90 47 6.9 3.8 43.7 110.7 17.5 M M
29000 -30.9 -23.6 200 90 46 6.9 3.8 42.3 108.2 16.7 M M
28000 -28.9 -20.0 200 90 46 6.9 3.8 41.3 106.4 16.1 M M
27000 -26.8 -16.2 200 89 46 6.6 3.6 40.2 104.4 15.4 M M
26000 -24.9 -12.8 200 88 46 6.6 3.6 38.9 102.1 14.6 M M
25000 -22.9 -9.2 200 88 45 6.6 3.6 37.8 100.1 13.9 M M
24000 -21.0 -5.8 205 87 45 5.0 2.8 36.6 97.9 13.0 M M
23000 -19.5 -3.1 205 84 43 5.2 2.9 34.8 94.7 11.7 M M
22000 -17.9 -0.2 205 82 42 5.2 2.9 33.2 91.8 10.5 M M
21000 -16.3 2.7 205 79 40 5.9 3.2 31.7 89.1 9.3 M M
20000 -14.6 5.7 205 74 38 5.9 3.2 30.3 86.5 8.2 M M
19500 -13.7 7.3 205 71 37 5.9 3.2 29.6 85.3 7.7 M M
19000 -12.8 9.0 210 69 35 5.8 3.2 29.0 84.2 7.2 M M
18500 -11.9 10.6 210 66 34 7.3 4.0 28.4 83.2 6.7 M M
18000 -10.8 12.6 210 63 32 7.4 4.1 28.0 82.5 6.4 M M
17500 -9.7 14.5 210 60 31 7.2 4.0 27.7 81.8 6.1 M M
17000 -8.6 16.5 210 57 29 6.6 3.6 27.1 80.9 5.7 M M
16500 -7.6 18.3 210 54 28 6.7 3.7 26.6 79.9 5.3 M M
16000 -6.7 19.9 210 53 27 6.4 3.5 26.1 79.0 4.8 M M
15500 -5.7 21.7 215 54 28 6.4 3.5 25.5 78.0 4.3 M M
15000 -4.8 23.4 215 55 28 6.1 3.3 25.0 77.0 3.8 M M
14500 -3.5 25.7 220 54 28 5.8 3.2 24.0 75.2 2.9 M M
14000 -2.6 27.3 220 52 27 6.6 3.6 23.4 74.2 2.3 M M
13500 -1.7 28.9 220 48 25 6.8 3.7 22.9 73.3 1.8 M M
13000 -0.7 30.7 220 44 23 7.6 4.2 22.5 72.5 1.3 M M
12500 0.4 32.7 220 43 22 8.9 4.4 22.2 71.9 1.0 M M
12000 1.5 34.7 220 41 21 8.2 4.5 21.9 71.4 0.7 M M
11500 2.7 36.9 220 39 20 8.3 4.5 21.7 71.0 0.4 M M
11000 3.9 39.0 220 36 19 7.5 4.1 21.4 70.6 0.2 M M
10500 4.9 40.8 220 34 18 6.0 3.3 21.0 69.8 -0.3 412 2.1
10250 5.4 41.7 220 33 17 10.4 5.7 20.8 69.4 -0.5 389 2.0
10000 6.3 43.3 215 30 15 11.9 6.5 21.0 69.8 -0.3 354 1.8
9750 7.0 44.6 215 29 15 8.3 4.6 21.0 69.7 -0.4 326 1.7
9500 7.7 45.9 215 29 15 10.0 5.5 20.9 69.7 -0.4 299 1.5
9250 8.4 47.1 215 28 14 6.9 3.8 20.9 69.6 -0.5 271 1.4
9000 8.8 47.8 215 28 14 7.0 3.9 20.6 69.0 -0.8 251 1.3
8750 9.5 49.1 215 27 14 10.0 5.5 20.5 69.0 -0.9 223 1.1
8500 10.1 50.2 215 27 14 9.4 5.2 20.5 68.9 -0.9 195 1.0
8250 10.8 51.4 215 26 13 8.6 4.7 20.5 68.9 -0.9 167 0.9
8000 11.4 52.5 215 25 13 7.5 4.1 20.3 68.6 -1.1 143 0.7
7750 12.0 53.6 215 25 13 8.3 4.6 20.2 68.3 -1.3 119 0.6
7500 12.6 54.7 215 25 13 9.2 5.0 20.1 68.2 -1.4 92 0.5
7250 13.2 55.8 215 25 13 7.6 4.2 20.0 68.1 -1.5 66 0.3
7000 13.7 56.7 215 24 12 6.0 3.3 19.8 67.6 -1.7 45 0.2
6750 14.2 57.6 210 24 12 7.5 4.1 19.6 67.2 -2.0 23 0.1
6500 14.8 58.6 210 22 12 8.2 4.5 19.4 67.0 -2.1 M M
6250 15.2 59.4 210 21 11 4.8 2.6 19.2 66.6 -2.4 M M
6000 15.4 59.7 210 19 10 2.9 1.6 18.7 65.7 -2.9 M M
5750 15.6 60.1 205 18 9 1.8 1.0 18.2 64.8 -3.5 M M
5500 15.4 59.7 205 14 7 -6.6 -3.6 17.4 63.2 -4.4 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
10/16/2025 at 0900 MDT | 10/16/2025 at 1200 MDT
|
CAPE... +19.1 LI... +2.1 | CAPE... +33.0 LI... +2.3
CINH... -22.1 K Index... -9.0 | CINH... -0.9 K Index... -2.2
|
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 -62.4 -80.3 225 42 21 0.7 0.4 | -61.8 -79.2 230 36 19 0.8 0.4
45000 -60.8 -77.4 225 77 40 4.0 2.2 | -60.0 -76.0 230 70 36 3.9 2.1
40000 -54.4 -65.9 215 88 45 4.2 2.3 | -53.8 -64.8 215 82 42 3.8 2.1
38000 -50.4 -58.7 210 88 45 7.0 3.9 | -49.9 -57.8 215 84 43 6.8 3.7
36000 -46.2 -51.2 205 87 45 7.0 3.9 | -45.8 -50.4 210 85 44 6.8 3.7
34000 -41.9 -43.4 205 87 45 7.2 4.0 | -41.7 -43.1 210 87 45 7.2 3.9
32000 -37.6 -35.7 200 88 45 7.2 4.0 | -37.4 -35.3 205 88 45 7.2 3.9
30000 -32.7 -26.9 200 89 46 7.3 4.0 | -32.6 -26.7 205 89 46 6.9 3.8
29000 -30.5 -22.9 200 90 46 7.3 4.0 | -30.6 -23.1 205 90 46 6.9 3.8
28000 -28.3 -18.9 200 91 47 7.2 4.0 | -28.5 -19.3 205 90 46 6.9 3.8
27000 -26.3 -15.3 200 92 47 5.6 3.1 | -26.5 -15.7 205 90 46 6.9 3.8
26000 -24.6 -12.3 205 93 48 5.7 3.1 | -24.4 -11.9 205 90 46 6.9 3.8
25000 -22.9 -9.2 205 93 48 5.7 3.1 | -22.3 -8.1 205 89 46 6.9 3.8
24000 -21.3 -6.3 205 94 48 4.5 2.5 | -20.4 -4.7 210 89 46 3.9 2.1
23000 -20.0 -4.0 205 90 47 4.3 2.4 | -19.6 -3.3 210 85 44 2.7 1.5
22000 -18.7 -1.7 205 87 45 4.3 2.4 | -18.8 -1.8 210 82 42 2.7 1.5
21000 -17.4 0.7 205 83 43 5.2 2.9 | -17.9 -0.2 210 78 40 3.4 1.9
20000 -15.8 3.6 210 77 40 5.2 2.8 | -16.9 1.6 210 70 36 3.5 1.9
19500 -15.1 4.8 210 74 38 5.2 2.8 | -16.4 2.5 215 66 34 3.5 1.9
19000 -14.3 6.3 210 70 36 5.2 2.8 | -15.9 3.4 215 62 32 3.5 1.9
18500 -13.5 7.7 210 67 35 6.1 3.4 | -15.3 4.5 215 58 30 4.7 2.6
18000 -12.5 9.5 210 64 33 6.6 3.6 | -14.5 5.9 220 54 28 5.6 3.1
17500 -11.5 11.3 210 61 31 6.6 3.6 | -13.7 7.3 220 50 26 5.6 3.1
17000 -10.5 13.1 215 58 30 6.9 3.8 | -12.7 9.1 220 47 24 7.1 3.9
16500 -9.5 14.9 215 55 28 6.9 3.8 | -11.7 10.9 225 44 23 7.0 3.8
16000 -8.4 16.9 215 52 27 7.1 3.9 | -10.7 12.7 225 41 21 7.2 3.9
15500 -6.8 19.8 220 49 25 7.2 3.9 | -9.1 15.6 225 38 20 7.2 4.0
15000 -5.8 21.6 220 46 24 6.4 3.5 | -8.0 17.6 230 36 19 7.2 3.9
14500 -4.9 23.2 220 43 22 6.5 3.6 | -6.9 19.6 230 34 17 7.2 3.9
14000 -4.0 24.8 225 40 21 5.9 3.2 | -5.8 21.6 230 31 16 8.1 4.5
13500 -3.1 26.4 225 37 19 5.8 3.2 | -4.6 23.7 230 28 15 8.4 4.6
13000 -2.3 27.9 230 34 18 6.6 3.6 | -3.3 26.1 230 26 13 8.2 4.5
12500 -1.3 29.7 230 31 16 7.2 4.0 | -2.2 28.0 230 25 13 8.1 4.5
12000 -0.2 31.6 235 28 15 7.7 4.2 | -1.0 30.2 230 23 12 8.1 4.4
11500 1.0 33.8 235 27 14 8.2 4.5 | 0.2 32.4 230 21 11 8.0 4.4
11000 2.1 35.8 235 25 13 7.7 4.2 | 1.3 34.3 235 20 10 7.6 4.2
10500 3.2 37.8 240 24 12 6.2 3.4 | 2.4 36.3 235 18 9 6.2 3.4
10250 3.7 38.7 240 24 12 10.8 5.9 | 2.9 37.2 235 17 9 11.1 6.1
10000 4.7 40.5 240 23 12 12.0 6.6 | 3.9 39.0 235 17 9 12.2 6.7
9750 5.3 41.5 240 22 11 8.0 4.4 | 4.5 40.1 235 16 8 7.8 4.3
9500 6.0 42.8 235 21 11 9.6 5.3 | 5.2 41.4 235 16 8 9.5 5.2
9250 6.6 43.9 235 21 11 7.4 4.0 | 5.8 42.4 235 15 8 7.1 3.9
9000 7.1 44.8 235 20 10 7.6 4.1 | 6.3 43.3 235 14 7 8.1 4.5
8750 7.8 46.0 235 20 10 9.5 5.2 | 7.0 44.6 235 14 7 10.8 6.0
8500 8.4 47.1 235 19 10 9.2 5.1 | 7.8 46.0 240 13 7 10.4 5.7
8250 9.1 48.4 230 19 10 8.7 4.8 | 8.5 47.3 240 13 7 9.5 5.2
8000 9.7 49.5 230 19 10 7.2 4.0 | 9.2 48.6 240 12 6 8.5 4.7
7750 10.2 50.4 230 18 9 7.5 4.1 | 9.9 49.8 240 12 6 10.0 5.5
7500 10.7 51.3 230 18 9 8.4 4.6 | 10.7 51.3 240 12 6 11.3 6.2
7250 11.3 52.3 225 18 9 7.0 3.8 | 11.5 52.7 245 12 6 9.2 5.1
7000 11.7 53.1 225 17 9 5.4 3.0 | 12.1 53.8 240 11 6 7.3 4.0
6750 12.2 54.0 225 17 9 7.7 4.2 | 12.7 54.9 240 11 6 10.9 6.0
6500 12.8 55.0 225 16 8 9.1 5.0 | 13.6 56.5 245 11 5 12.8 7.0
6250 13.4 56.1 220 16 8 6.6 3.6 | 14.5 58.1 245 10 5 10.3 5.7
6000 13.7 56.7 220 15 8 5.1 2.8 | 15.2 59.4 245 10 5 9.3 5.1
5750 14.1 57.4 215 14 7 6.0 3.3 | 15.9 60.6 245 10 5 10.1 5.6
5500 14.5 58.1 220 10 5 8.0 4.4 | 16.9 62.4 250 9 4 16.7 9.1
10/16/2025 at 1500 MDT | 10/16/2025 at 1800 MDT
|
CAPE... +8.4 LI... +0.6 | CAPE... 0.0 LI... +1.8
CINH... -2.3 K Index... +4.4 | CINH... 0.0 K Index... +0.7
|
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 -61.6 -78.9 230 38 19 2.7 1.5 | -60.9 -77.6 225 36 19 2.0 1.1
45000 -57.6 -71.7 225 63 33 2.7 1.5 | -57.7 -71.9 230 63 32 3.5 1.9
40000 -53.4 -64.1 220 77 40 2.3 1.3 | -52.1 -61.8 230 73 37 3.4 1.9
38000 -49.8 -57.6 215 80 41 6.4 3.5 | -49.4 -56.9 225 76 39 4.6 2.5
36000 -46.0 -50.8 215 83 43 6.4 3.5 | -46.7 -52.1 220 78 40 4.6 2.5
34000 -41.9 -43.4 215 85 44 7.2 4.0 | -43.1 -45.6 220 81 41 8.0 4.4
32000 -37.6 -35.7 215 86 44 7.2 4.0 | -38.3 -36.9 220 82 42 8.0 4.4
30000 -33.5 -28.3 215 86 44 6.2 3.4 | -34.0 -29.2 220 81 42 5.4 3.0
29000 -31.6 -24.9 215 85 44 6.2 3.4 | -32.4 -26.3 225 79 40 5.4 3.0
28000 -29.3 -20.7 215 84 43 6.3 3.4 | -30.8 -23.4 225 76 39 5.4 3.0
27000 -27.3 -17.1 215 83 43 7.5 4.1 | -28.6 -19.5 225 74 38 7.6 4.2
26000 -25.0 -13.0 215 82 42 7.4 4.1 | -26.3 -15.3 225 72 37 7.4 4.1
25000 -22.8 -9.0 215 81 42 7.4 4.1 | -24.1 -11.4 220 71 36 7.4 4.1
24000 -20.8 -5.4 215 80 41 3.2 1.8 | -22.0 -7.6 220 69 35 4.3 2.4
23000 -20.2 -4.4 215 74 38 1.9 1.1 | -21.0 -5.8 225 63 33 3.4 1.9
22000 -19.6 -3.3 215 69 36 1.9 1.0 | -20.0 -4.0 225 58 30 3.4 1.9
21000 -19.0 -2.2 220 63 33 2.9 1.6 | -19.0 -2.2 230 53 27 3.0 1.7
20000 -18.1 -0.6 220 53 27 3.0 1.6 | -18.1 -0.6 230 45 23 3.1 1.7
19500 -17.7 0.1 225 48 25 3.0 1.6 | -17.6 0.3 230 40 21 3.1 1.7
19000 -17.3 0.9 225 43 22 3.0 1.7 | -17.1 1.2 230 36 19 3.1 1.7
18500 -16.8 1.8 230 38 20 6.2 3.4 | -16.6 2.1 230 32 17 5.2 2.9
18000 -15.6 3.9 230 36 18 7.6 4.2 | -15.7 3.7 230 29 15 6.1 3.4
17500 -14.4 6.1 230 34 17 7.7 4.2 | -14.8 5.4 225 26 13 6.4 3.5
17000 -13.3 8.1 235 32 16 7.6 4.2 | -13.8 7.2 225 24 12 7.6 4.2
16500 -12.2 10.0 235 30 15 7.6 4.2 | -12.6 9.3 220 22 11 7.5 4.1
16000 -11.1 12.0 235 28 14 7.5 4.1 | -11.5 11.3 220 21 11 8.3 4.5
15500 -10.0 14.0 240 26 14 7.5 4.1 | -10.3 13.5 220 20 10 8.3 4.6
15000 -8.9 16.0 240 25 13 7.9 4.3 | -9.0 15.8 225 19 10 8.5 4.6
14500 -7.6 18.3 240 23 12 8.2 4.5 | -7.8 18.0 225 19 10 8.6 4.7
14000 -6.4 20.5 240 22 11 8.3 4.6 | -6.5 20.3 230 18 9 8.7 4.8
13500 -5.2 22.6 240 20 10 8.7 4.7 | -5.2 22.6 225 18 9 9.0 5.0
13000 -3.9 25.0 240 19 10 8.7 4.8 | -3.1 26.4 225 17 9 9.3 5.1
12500 -1.9 28.6 235 17 9 9.0 4.9 | -1.8 28.8 225 16 8 9.4 5.1
12000 -0.6 30.9 235 16 8 9.2 5.1 | -0.4 31.3 225 15 8 9.1 5.0
11500 0.8 33.4 235 16 8 9.3 5.1 | 1.0 33.8 230 15 8 9.0 5.0
11000 2.1 35.8 235 15 8 7.9 4.3 | 2.3 36.1 230 15 8 7.6 4.2
10500 3.2 37.8 235 14 7 5.8 3.2 | 3.4 38.1 230 14 7 5.6 3.1
10250 3.7 38.7 235 14 7 12.3 6.8 | 3.9 39.0 235 14 7 12.2 6.7
10000 4.8 40.6 235 13 7 13.5 7.4 | 5.0 41.0 235 14 7 13.0 7.1
9750 5.5 41.9 240 12 6 7.5 4.1 | 5.6 42.1 235 13 7 6.7 3.7
9500 6.1 43.0 240 11 6 10.0 5.5 | 6.2 43.2 240 13 7 9.2 5.0
9250 6.8 44.2 245 11 6 5.9 3.2 | 6.8 44.2 240 13 7 5.6 3.1
9000 7.1 44.8 250 10 5 7.5 4.1 | 7.2 45.0 245 12 6 6.6 3.6
8750 8.0 46.4 250 10 5 12.1 6.7 | 7.8 46.0 250 12 6 10.1 5.5
8500 8.8 47.8 255 10 5 11.6 6.4 | 8.5 47.3 255 12 6 9.7 5.3
8250 9.7 49.5 255 10 5 9.2 5.0 | 9.2 48.6 265 12 6 7.7 4.2
8000 10.2 50.4 255 10 5 7.5 4.1 | 9.7 49.5 270 12 6 6.4 3.5
7750 10.9 51.6 260 10 5 10.8 5.9 | 10.3 50.5 275 12 6 9.7 5.3
7500 11.8 53.2 260 10 5 12.4 6.8 | 11.1 52.0 280 13 7 11.0 6.0
7250 12.6 54.7 260 10 5 9.1 5.0 | 11.8 53.2 280 13 7 8.6 4.7
7000 13.2 55.8 260 10 5 6.6 3.6 | 12.4 54.3 285 13 7 6.9 3.8
6750 13.8 56.8 260 10 5 11.5 6.3 | 13.0 55.4 285 13 7 10.6 5.8
6500 14.8 58.6 260 10 5 12.8 7.0 | 13.9 57.0 290 13 7 11.4 6.3
6250 15.6 60.1 260 10 5 9.5 5.2 | 14.6 58.3 290 13 7 8.7 4.8
6000 16.3 61.3 265 10 5 8.2 4.5 | 15.2 59.4 290 13 7 7.7 4.2
5750 17.0 62.6 265 9 5 11.0 6.0 | 15.8 60.4 295 12 6 9.6 5.3
5500 18.0 64.4 270 8 4 18.9 10.4 | 16.6 61.9 295 10 5 10.1 5.6
________________________________________________________________________________
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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