Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
003
UXUS97 KBOU 301230
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0529 MST Sunday, November 30, 2025
This forecast is for Sunday, November 30, 2025:
If the trigger temperature of 45.4 F/7.5 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 6850 ft MSL (1558 ft AGL)
Forecast maximum temperature................... 26.0 F/-3.8 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 6055 ft MSL (763 ft AGL)
Thermal soaring outlook for Monday 12/01....... Fair
Wave Soaring Index............................. Fair
Wave Soaring Index trend (to 1700 MST)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Weak PVA
Potential height of wave....................... 38440 ft MSL (33148 ft AGL)
Wave soaring outlook for Monday 12/01.......... Good
Remarks... Areas of snow developing this afternoon and evening. Cold. Better
wave soaring by Monday afternoon.
Sunrise/Sunset.................... 07:01:03 / 16:35:36 MST
Total possible sunshine........... 9 hr 34 min 33 sec (574 min 33 sec)
Altitude of sun at 11:48:20 MST... 28.40 degrees
Upper air data from numerical model forecast valid on 11/30/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 17010 ft MSL (11718 ft AGL)
Lifted condensation level....... 9437 ft MSL (4145 ft AGL)
Lifted index.................... +16.2
K index......................... +6.5
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 -57.8 -72.0 280 51 26 0.5 0.3 M M M M M
45000 -57.2 -71.0 275 61 31 0.5 0.3 M M M M M
40000 -58.8 -73.8 270 74 38 -1.3 -0.7 M M M M M
38000 -59.3 -74.7 270 77 40 0.8 0.5 M M M M M
36000 -58.9 -74.0 270 75 39 0.8 0.4 M M M M M
34000 -58.4 -73.1 270 73 38 0.2 0.1 M M M M M
32000 -54.6 -66.3 270 68 35 7.1 3.9 M M M M M
30000 -50.3 -58.5 270 62 32 7.3 4.0 M M M M M
29000 -48.1 -54.6 270 59 30 7.5 4.1 25.3 77.5 21.6 M M
28000 -45.3 -49.5 270 56 29 7.5 4.1 24.1 75.5 21.1 M M
27000 -43.0 -45.4 270 54 28 7.5 4.1 23.4 74.1 20.7 M M
26000 -40.7 -41.3 270 52 27 7.8 4.3 22.6 72.7 20.3 M M
25000 -38.4 -37.1 265 51 26 7.8 4.3 21.8 71.3 20.0 M M
24000 -36.0 -32.8 265 51 26 7.8 4.3 21.2 70.1 19.7 M M
23000 -33.6 -28.5 260 49 25 8.2 4.5 20.5 68.9 19.4 M M
22000 -31.2 -24.2 260 46 24 8.2 4.5 19.9 67.9 19.1 M M
21000 -28.7 -19.7 255 44 22 8.2 4.5 19.5 67.0 19.0 M M
20000 -26.3 -15.3 255 40 21 8.0 4.4 18.8 65.8 18.6 M M
19500 -25.2 -13.4 260 38 20 8.0 4.4 18.5 65.3 18.4 M M
19000 -24.0 -11.2 260 37 19 8.0 4.4 18.2 64.8 18.3 M M
18500 -22.8 -9.0 260 35 18 8.0 4.4 18.0 64.3 18.2 M M
18000 -21.6 -6.9 260 33 17 7.5 4.1 17.6 63.7 18.0 M M
17500 -20.5 -4.9 265 32 17 7.6 4.1 17.2 63.0 17.8 M M
17000 -19.4 -2.9 265 31 16 7.8 4.3 16.9 62.4 17.5 M M
16500 -18.2 -0.8 270 30 15 7.8 4.3 16.5 61.8 17.3 M M
16000 -17.0 1.4 275 28 15 7.8 4.3 16.2 61.2 17.2 M M
15500 -15.9 3.4 275 27 14 7.8 4.3 15.9 60.6 16.9 M M
15000 -14.7 5.5 275 26 13 7.8 4.3 15.6 60.0 16.7 M M
14500 -13.6 7.5 275 25 13 7.1 3.9 15.2 59.3 16.5 M M
14000 -12.0 10.4 280 23 12 6.9 3.8 14.5 58.2 16.0 M M
13500 -11.0 12.2 275 20 11 6.5 3.6 14.0 57.2 15.6 M M
13000 -10.1 13.8 275 18 9 6.5 3.6 13.5 56.3 15.2 M M
12500 -9.1 15.6 270 16 8 6.4 3.5 12.9 55.3 14.8 M M
12000 -8.1 17.4 265 14 7 6.1 3.4 12.4 54.3 14.4 M M
11500 -7.3 18.9 260 11 6 5.4 3.0 11.7 53.1 13.8 M M
11000 -6.5 20.3 255 9 5 5.0 2.7 11.1 51.9 13.3 M M
10500 -5.9 21.4 245 7 4 4.0 2.2 10.2 50.3 12.5 M M
10250 -5.6 21.9 240 6 3 4.6 2.5 9.7 49.5 12.1 M M
10000 -5.2 22.6 235 6 3 2.5 1.4 9.3 48.7 11.8 M M
9750 -5.1 22.8 235 5 3 1.7 0.9 8.6 47.5 11.1 M M
9500 -4.9 23.2 230 4 2 3.2 1.8 8.1 46.6 10.7 M M
9250 -4.7 23.5 225 3 2 2.5 1.4 7.6 45.6 10.2 M M
9000 -4.6 23.7 220 3 1 0.5 0.3 6.9 44.5 9.6 M M
8750 -4.7 23.5 215 2 1 -2.8 -1.5 6.1 42.9 8.8 M M
8500 -5.0 23.0 215 2 1 -3.6 -2.0 5.0 41.1 7.8 M M
8250 -5.3 22.5 215 1 1 -5.4 -2.9 4.0 39.2 6.8 M M
8000 -5.8 21.6 190 1 0 -8.1 -4.4 2.7 36.8 5.6 M M
7750 -6.4 20.5 000 0 0 -9.0 -5.0 1.3 34.3 4.2 M M
7500 -7.2 19.0 100 1 1 -9.4 -5.1 -0.2 31.6 2.8 M M
7250 -7.7 18.1 100 1 1 -4.5 -2.5 -1.5 29.3 1.5 M M
7000 -7.9 17.8 100 1 1 -1.8 -1.0 -2.4 27.6 0.6 M M
6750 -8.1 17.4 105 1 0 -1.1 -0.6 -3.3 26.0 -0.3 301 1.5
6500 -8.1 17.4 075 1 0 -2.0 -1.1 -4.1 24.6 -1.1 295 1.5
6250 -8.4 16.9 050 1 1 -4.0 -2.2 -5.2 22.7 -2.1 296 1.5
6000 -8.7 16.3 040 1 1 -4.5 -2.5 -6.2 20.9 -3.1 297 1.5
5750 -8.9 16.0 035 2 1 -0.3 -0.2 -7.2 19.1 -4.1 298 1.5
5500 -8.5 16.7 030 2 1 11.3 6.2 -7.5 18.5 -4.5 279 1.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/30/2025 at 0800 MST | 11/30/2025 at 1100 MST
|
CAPE... 0.0 LI... +4.6 | CAPE... 0.0 LI... +4.9
CINH... 0.0 K Index... +7.5 | CINH... 0.0 K Index... +4.6
|
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 -57.2 -71.0 285 48 25 0.3 0.2 | -57.4 -71.3 280 42 22 0.3 0.2
45000 -56.7 -70.1 275 57 29 0.3 0.2 | -56.9 -70.4 270 54 28 0.4 0.2
40000 -58.7 -73.7 270 71 37 -1.5 -0.8 | -58.4 -73.1 265 71 37 -1.1 -0.6
38000 -59.3 -74.7 270 76 39 1.0 0.5 | -58.9 -74.0 265 77 39 0.7 0.4
36000 -58.8 -73.8 265 75 39 0.8 0.5 | -58.5 -73.3 265 77 39 0.6 0.3
34000 -58.3 -72.9 265 74 38 0.1 0.1 | -58.1 -72.6 260 77 39 -0.1 -0.1
32000 -54.5 -66.1 265 70 36 7.3 4.0 | -54.3 -65.7 265 75 39 7.4 4.0
30000 -50.2 -58.4 270 66 34 7.4 4.1 | -49.9 -57.8 265 74 38 7.5 4.1
29000 -47.2 -53.0 270 61 32 8.0 4.4 | -46.8 -52.2 265 68 35 8.4 4.6
28000 -44.8 -48.6 265 58 30 8.0 4.4 | -44.3 -47.7 265 63 32 8.4 4.6
27000 -42.4 -44.3 265 54 28 8.0 4.4 | -41.8 -43.2 265 58 30 8.4 4.6
26000 -39.9 -39.8 260 52 27 8.6 4.7 | -39.2 -38.6 260 55 28 8.8 4.8
25000 -37.3 -35.1 260 50 26 8.6 4.7 | -36.5 -33.7 260 54 28 8.8 4.9
24000 -34.8 -30.6 260 48 25 8.7 4.8 | -33.9 -29.0 255 53 27 8.8 4.8
23000 -32.7 -26.9 255 45 23 5.9 3.2 | -31.5 -24.7 255 50 26 7.6 4.1
22000 -30.9 -23.6 250 42 22 5.8 3.2 | -29.2 -20.6 250 46 24 7.5 4.1
21000 -29.2 -20.6 245 39 20 5.8 3.2 | -27.0 -16.6 250 43 22 7.8 4.3
20000 -26.9 -16.4 240 37 19 8.0 4.4 | -25.3 -13.5 245 38 20 5.3 2.9
19500 -25.8 -14.4 240 36 18 8.0 4.4 | -24.5 -12.1 245 36 19 5.3 2.9
19000 -24.6 -12.3 235 34 18 8.0 4.4 | -23.7 -10.7 240 34 18 5.3 2.9
18500 -23.4 -10.1 235 33 17 8.1 4.4 | -22.9 -9.2 240 32 16 5.0 2.8
18000 -22.3 -8.1 235 32 17 6.8 3.7 | -21.9 -7.4 240 30 15 8.3 4.6
17500 -21.3 -6.3 235 32 16 7.0 3.8 | -20.6 -5.1 240 28 15 8.5 4.7
17000 -20.2 -4.4 240 31 16 8.5 4.7 | -19.3 -2.7 245 27 14 7.4 4.1
16500 -18.8 -1.8 240 30 15 9.3 5.1 | -18.5 -1.3 245 25 13 5.7 3.1
16000 -17.5 0.5 240 29 15 9.2 5.0 | -17.2 1.0 245 22 12 6.3 3.5
15500 -16.2 2.8 240 28 14 8.6 4.7 | -16.2 2.8 245 22 11 6.7 3.7
15000 -14.9 5.2 235 26 13 8.7 4.8 | -15.3 4.5 245 21 11 7.1 3.9
14500 -13.7 7.3 235 24 13 7.3 4.0 | -14.1 6.6 245 21 11 7.9 4.3
14000 -12.0 10.4 230 22 11 7.0 3.8 | -13.0 8.6 250 21 11 7.8 4.3
13500 -11.1 12.0 225 20 10 6.3 3.4 | -11.9 10.6 245 20 10 6.9 3.8
13000 -10.1 13.8 225 18 9 5.8 3.2 | -10.9 12.4 240 19 10 6.9 3.8
12500 -9.4 15.1 215 16 8 4.4 2.4 | -9.9 14.2 235 18 9 5.5 3.0
12000 -8.7 16.3 210 15 7 4.5 2.5 | -9.1 15.6 230 16 8 5.7 3.1
11500 -8.0 17.6 200 13 7 4.5 2.5 | -8.5 16.7 225 14 7 2.6 1.4
11000 -7.3 18.9 185 12 6 4.1 2.3 | -8.1 17.4 215 12 6 2.8 1.5
10500 -6.8 19.8 175 11 6 3.0 1.7 | -7.8 18.0 210 11 5 1.3 0.7
10250 -6.6 20.1 165 11 6 3.8 2.1 | -7.7 18.1 205 10 5 1.6 0.9
10000 -6.3 20.7 160 11 6 1.3 0.7 | -7.5 18.5 200 9 5 1.2 0.7
9750 -6.4 20.5 155 11 6 -0.3 -0.1 | -7.5 18.5 195 9 5 -1.0 -0.6
9500 -6.3 20.7 150 11 5 1.1 0.6 | -7.7 18.1 190 8 4 -2.5 -1.4
9250 -6.3 20.7 145 10 5 0.8 0.4 | -7.9 17.8 180 8 4 -1.6 -0.9
9000 -6.2 20.8 135 10 5 -1.0 -0.5 | -8.0 17.6 170 8 4 -3.7 -2.0
8750 -6.4 20.5 135 10 5 -2.9 -1.6 | -8.4 16.9 160 7 4 -5.6 -3.1
8500 -6.6 20.1 135 10 5 -2.8 -1.6 | -8.8 16.2 150 7 3 -5.2 -2.9
8250 -6.9 19.6 135 9 5 -3.3 -1.8 | -9.2 15.4 140 6 3 -5.1 -2.8
8000 -7.1 19.2 135 9 4 -3.9 -2.1 | -9.6 14.7 125 6 3 -4.9 -2.7
7750 -7.5 18.5 130 8 4 -4.0 -2.2 | -9.9 14.2 115 5 3 -3.3 -1.8
7500 -7.8 18.0 130 7 4 -3.9 -2.1 | -10.0 14.0 110 5 3 -1.9 -1.0
7250 -8.1 17.4 125 6 3 -4.6 -2.5 | -10.1 13.8 105 5 3 -0.1 -0.1
7000 -8.4 16.9 120 4 2 -4.5 -2.5 | -10.1 13.8 085 5 2 1.4 0.8
6750 -8.8 16.2 105 2 1 -6.4 -3.5 | -10.0 14.0 065 5 2 1.0 0.5
6500 -9.3 15.3 025 1 1 -4.6 -2.5 | -9.8 14.4 045 5 3 5.2 2.8
6250 -9.4 15.1 020 2 1 -0.7 -0.4 | -9.2 15.4 035 5 3 10.0 5.5
6000 -9.5 14.9 015 2 1 -2.9 -1.6 | -8.5 16.7 030 5 3 10.1 5.5
5750 -9.7 14.5 015 3 1 2.6 1.4 | -7.7 18.1 025 5 3 11.2 6.1
5500 -9.0 15.8 015 3 2 15.5 8.5 | -6.7 19.9 020 5 3 16.9 9.3
11/30/2025 at 1400 MST | 11/30/2025 at 1700 MST
|
CAPE... 0.0 LI... +5.1 | CAPE... +0.7 LI... +4.1
CINH... 0.0 K Index... +9.5 | CINH... 0.0 K Index... +11.8
|
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 -57.1 -70.8 275 42 22 0.5 0.3 | -57.4 -71.3 275 45 23 0.9 0.5
45000 -56.3 -69.3 275 51 26 0.5 0.3 | -56.0 -68.8 270 49 25 0.9 0.5
40000 -57.4 -71.3 270 69 35 -0.9 -0.5 | -55.2 -67.4 265 65 33 0.5 0.2
38000 -57.8 -72.0 265 76 39 0.2 0.1 | -55.0 -67.0 260 72 37 -0.6 -0.3
36000 -57.7 -71.9 260 79 41 0.2 0.1 | -55.3 -67.5 260 78 40 -0.5 -0.3
34000 -57.6 -71.7 260 83 43 -0.3 -0.2 | -55.7 -68.3 255 86 44 -0.6 -0.4
32000 -54.0 -65.2 255 78 40 7.2 3.9 | -52.7 -62.9 255 87 45 6.3 3.5
30000 -49.2 -56.6 255 69 35 8.3 4.5 | -48.5 -55.3 250 87 45 6.5 3.6
29000 -46.5 -51.7 255 66 34 9.0 5.0 | -46.5 -51.7 250 83 43 6.6 3.6
28000 -43.8 -46.8 255 63 32 9.1 5.0 | -44.5 -48.1 250 79 41 6.6 3.6
27000 -41.0 -41.8 255 60 31 9.1 5.0 | -42.6 -44.7 250 75 39 6.6 3.6
26000 -38.5 -37.3 255 58 30 8.0 4.4 | -40.4 -40.7 250 70 36 8.2 4.5
25000 -36.1 -33.0 255 56 29 8.0 4.4 | -37.9 -36.2 245 63 33 8.2 4.5
24000 -33.8 -28.8 255 55 28 8.0 4.4 | -35.5 -31.9 245 56 29 8.2 4.5
23000 -31.4 -24.5 255 53 27 7.6 4.1 | -33.0 -27.4 245 51 26 8.3 4.6
22000 -29.2 -20.6 255 51 26 7.6 4.1 | -30.5 -22.9 250 50 26 8.3 4.6
21000 -26.9 -16.4 255 49 25 7.6 4.2 | -28.0 -18.4 255 48 25 8.4 4.6
20000 -24.8 -12.6 255 48 25 6.8 3.7 | -26.0 -14.8 260 45 23 6.0 3.3
19500 -23.8 -10.8 255 47 24 6.8 3.7 | -25.1 -13.2 260 42 22 6.0 3.3
19000 -22.8 -9.0 255 47 24 6.8 3.8 | -24.2 -11.6 260 39 20 6.0 3.3
18500 -21.8 -7.2 255 46 24 6.9 3.8 | -23.3 -9.9 260 36 19 6.0 3.3
18000 -20.8 -5.4 255 46 23 6.3 3.5 | -22.4 -8.3 260 34 17 7.1 3.9
17500 -19.9 -3.8 250 43 22 6.1 3.4 | -21.2 -6.2 265 33 17 7.7 4.3
17000 -19.0 -2.2 250 41 21 6.2 3.4 | -20.1 -4.2 265 32 16 7.9 4.3
16500 -18.1 -0.6 250 38 20 6.4 3.5 | -18.2 -0.8 265 29 15 8.5 4.7
16000 -16.7 1.9 245 35 18 6.2 3.4 | -17.0 1.4 260 27 14 8.1 4.4
15500 -15.8 3.6 250 34 18 5.9 3.2 | -15.9 3.4 260 26 13 7.3 4.0
15000 -14.9 5.2 250 34 17 5.8 3.2 | -14.8 5.4 260 26 13 7.3 4.0
14500 -14.1 6.6 250 30 16 5.7 3.1 | -13.8 7.2 255 26 13 6.4 3.5
14000 -13.3 8.1 245 26 13 5.8 3.2 | -12.9 8.8 250 26 13 6.7 3.7
13500 -12.5 9.5 240 22 11 5.1 2.8 | -12.1 10.2 250 25 13 4.5 2.5
13000 -11.7 10.9 235 20 10 5.1 2.8 | -11.4 11.5 245 25 13 4.8 2.6
12500 -10.9 12.4 230 19 10 6.0 3.3 | -10.8 12.6 245 24 12 3.4 1.9
12000 -10.0 14.0 225 18 9 6.3 3.5 | -10.3 13.5 240 22 11 3.6 2.0
11500 -9.4 15.1 220 17 9 2.3 1.3 | -9.9 14.2 240 19 10 0.7 0.4
11000 -9.0 15.8 225 15 8 3.2 1.7 | -9.8 14.4 240 17 9 0.8 0.4
10500 -9.0 15.8 225 13 7 -3.2 -1.8 | -9.8 14.4 235 15 8 -1.1 -0.6
10250 -9.2 15.4 220 12 6 -2.6 -1.4 | -9.9 14.2 235 14 7 -1.1 -0.6
10000 -9.4 15.1 220 10 5 -2.1 -1.1 | -10.0 14.0 235 13 7 -0.6 -0.3
9750 -9.5 14.9 215 10 5 -3.0 -1.6 | -10.0 14.0 235 12 6 -1.9 -1.0
9500 -9.8 14.4 210 9 5 -4.5 -2.5 | -10.2 13.6 225 11 6 -3.2 -1.7
9250 -10.1 13.8 200 9 4 -4.1 -2.2 | -10.4 13.3 215 11 5 -3.4 -1.9
9000 -10.4 13.3 185 8 4 -4.4 -2.4 | -10.7 12.7 205 11 5 -1.3 -0.7
8750 -10.7 12.7 170 9 5 -1.1 -0.6 | -10.6 12.9 195 11 6 2.4 1.3
8500 -10.6 12.9 160 9 5 2.0 1.1 | -10.4 13.3 185 11 6 3.0 1.6
8250 -10.5 13.1 150 10 5 1.3 0.7 | -10.2 13.6 175 11 6 2.2 1.2
8000 -10.3 13.5 145 10 5 3.6 2.0 | -10.0 14.0 170 12 6 5.0 2.8
7750 -10.0 14.0 135 8 4 4.7 2.6 | -9.5 14.9 165 10 5 6.5 3.6
7500 -9.7 14.5 125 7 4 3.1 1.7 | -9.1 15.6 160 9 5 4.8 2.6
7250 -9.4 15.1 110 6 3 4.2 2.3 | -8.7 16.3 155 8 4 4.7 2.6
7000 -9.1 15.6 095 4 2 5.6 3.1 | -8.4 16.9 145 6 3 4.4 2.4
6750 -8.7 16.3 060 3 2 5.6 3.1 | -8.1 17.4 130 5 2 3.8 2.1
6500 -8.2 17.2 030 3 2 6.9 3.8 | -7.8 18.0 115 4 2 3.9 2.1
6250 -7.6 18.3 015 3 2 9.9 5.4 | -7.5 18.5 095 3 2 6.7 3.7
6000 -6.8 19.8 005 3 2 11.5 6.3 | -6.9 19.6 060 2 1 8.5 4.7
5750 -5.9 21.4 360 3 2 10.0 5.5 | -6.3 20.7 030 3 1 7.0 3.8
5500 -5.2 22.6 355 3 2 11.1 6.1 | -5.8 21.6 015 3 2 8.4 4.6
________________________________________________________________________________
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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