Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
915
UXUS97 KGJT 241306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Monday, November 24, 2025
This forecast is for Monday, November 24, 2025:
If the trigger temperature of 45.6 F/7.5 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 512 ft/min (2.6 m/s)
Maximum height of thermals.................. 12330 ft MSL (6723 ft AGL)
Forecast maximum temperature................... 52.0 F/11.6 C
Time of trigger temperature.................... 1045 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................. 10271 ft MSL (4665 ft AGL)
Thermal soaring outlook for Tuesday 11/25...... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:07:46 / 16:54:09 MST
Total possible sunshine........... 9 hr 46 min 23 sec (586 min 23 sec)
Altitude of sun at 12:00:58 MST... 30.17 degrees
Upper air data from rawinsonde observation taken on 11/24/2025 at 0500 MST
Freezing level.................. 5642 ft MSL (35 ft AGL)
Additional freezing level....... 7584 ft MSL (1977 ft AGL)
Convective condensation level... 10719 ft MSL (5112 ft AGL)
Lifted condensation level....... 11796 ft MSL (6190 ft AGL)
Lifted index.................... +6.3
K index......................... +4.3
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 -60.1 -76.2 270 42 22 0.9 0.5 M M M M M
45000 -58.7 -73.7 270 38 20 0.8 0.5 M M M M M
40000 -60.1 -76.2 290 43 22 -1.0 -0.5 M M M M M
38000 -59.7 -75.5 295 49 25 3.0 1.6 M M M M M
36000 -57.9 -72.2 305 60 31 3.0 1.6 M M M M M
34000 -55.3 -67.5 305 69 36 8.0 4.4 M M M M M
32000 -50.7 -59.3 310 65 33 7.8 4.3 M M M M M
30000 -45.8 -50.4 310 60 31 9.0 4.9 29.2 84.5 13.6 M M
29000 -43.1 -45.6 310 58 30 9.0 5.0 28.8 83.8 13.5 M M
28000 -40.4 -40.7 305 55 28 9.0 5.0 28.6 83.4 13.4 M M
27000 -37.7 -35.9 305 53 27 8.9 4.9 28.4 83.2 13.5 M M
26000 -35.1 -31.2 305 51 26 8.8 4.8 27.9 82.3 13.3 M M
25000 -32.4 -26.3 300 50 26 8.8 4.8 27.6 81.6 13.1 M M
24000 -29.8 -21.6 300 49 25 8.6 4.7 27.3 81.2 13.1 M M
23000 -27.5 -17.5 300 49 25 7.5 4.1 26.5 79.7 12.5 M M
22000 -25.3 -13.5 300 48 25 7.5 4.1 25.7 78.2 12.0 M M
21000 -23.1 -9.6 300 47 24 6.5 3.5 25.0 76.9 11.5 M M
20000 -21.4 -6.5 305 46 24 5.7 3.1 23.4 74.2 10.3 M M
19500 -20.1 -4.2 305 45 23 5.7 3.1 22.4 72.3 9.5 M M
19000 -19.2 -2.6 305 45 23 5.7 3.2 21.7 71.0 9.0 M M
18500 -18.4 -1.1 305 44 23 5.1 2.8 21.0 69.8 8.4 M M
18000 -17.7 0.1 310 42 22 5.0 2.8 20.2 68.3 7.8 M M
17500 -16.9 1.6 310 41 21 5.1 2.8 19.4 66.9 7.1 M M
17000 -16.2 2.8 310 39 20 5.2 2.8 18.6 65.4 6.4 M M
16500 -15.4 4.3 310 38 19 5.2 2.8 17.8 64.0 5.8 M M
16000 -14.5 5.9 305 36 19 6.2 3.4 17.1 62.8 5.2 M M
15500 -13.6 7.5 305 35 18 6.2 3.4 16.5 61.7 4.7 M M
15000 -12.7 9.1 305 34 17 5.4 3.0 15.9 60.5 4.1 M M
14500 -11.9 10.6 305 33 17 5.4 3.0 15.1 59.2 3.5 M M
14000 -11.1 12.0 300 31 16 4.6 2.5 14.4 57.9 2.8 M M
13500 -10.5 13.1 300 30 15 4.4 2.4 13.5 56.3 2.0 M M
13000 -9.8 14.4 300 28 14 4.0 2.2 12.6 54.7 1.2 M M
12500 -9.3 15.3 295 26 13 3.8 2.1 11.6 52.9 0.3 M M
12000 -8.8 16.2 295 23 12 4.6 2.5 10.7 51.2 -0.6 491 2.5
11500 -8.0 17.6 295 21 11 5.1 2.8 9.9 49.9 -1.4 455 2.3
11000 -7.3 18.9 295 18 9 5.8 3.2 9.2 48.6 -2.1 418 2.1
10500 -6.4 20.5 295 15 8 5.8 3.2 8.7 47.6 -2.7 377 1.9
10250 -6.0 21.2 295 14 7 8.2 4.5 8.4 47.1 -3.0 357 1.8
10000 -5.3 22.5 295 13 6 8.8 4.8 8.4 47.1 -3.1 329 1.7
9750 -4.8 23.4 295 12 6 7.0 3.8 8.2 46.7 -3.3 305 1.6
9500 -4.3 24.3 295 11 5 7.6 4.2 8.0 46.4 -3.5 282 1.4
9250 -3.7 25.3 300 9 5 7.0 3.9 7.8 46.1 -3.7 259 1.3
9000 -3.2 26.2 300 9 5 7.4 4.1 7.6 45.7 -3.9 236 1.2
8750 -2.6 27.3 300 8 4 8.1 4.4 7.5 45.4 -4.1 212 1.1
8500 -2.1 28.2 300 7 4 7.9 4.4 7.3 45.2 -4.2 187 0.9
8250 -1.5 29.3 300 6 3 7.2 3.9 7.2 44.9 -4.4 163 0.8
8000 -1.0 30.2 300 5 3 6.7 3.7 6.9 44.5 -4.7 140 0.7
7750 -0.5 31.1 300 4 2 7.1 3.9 6.7 44.1 -4.9 118 0.6
7500 0.0 32.0 300 3 2 6.8 3.7 6.5 43.7 -5.1 95 0.5
7250 0.5 32.9 305 3 1 6.5 3.6 6.3 43.3 -5.4 73 0.4
7000 1.0 33.8 305 2 1 6.1 3.4 6.0 42.8 -5.7 52 0.3
6750 1.4 34.5 315 1 1 5.5 3.0 5.7 42.3 -6.0 32 0.2
6500 1.8 35.2 330 1 0 4.4 2.4 5.3 41.6 -6.4 13 0.1
6250 2.0 35.6 000 0 0 1.5 0.8 4.8 40.7 -6.9 M M
6000 2.2 36.0 060 1 0 8.1 4.5 4.3 39.8 -7.4 M M
5750 2.9 37.2 100 1 0 2.3 1.3 4.3 39.7 -7.5 M M
5500 M M M M M M M M M M M M
5250 M M M M M M M M M M M M
5000 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/24/2025 at 0800 MST | 11/24/2025 at 1100 MST
|
CAPE... 0.0 LI... +5.0 | CAPE... +1.2 LI... +4.7
CINH... -0.1 K Index... +5.1 | CINH... -0.7 K Index... +5.1
|
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 -61.2 -78.2 265 36 18 2.8 1.5 | -61.2 -78.2 260 41 21 2.6 1.4
45000 -57.0 -70.6 270 37 19 0.7 0.4 | -57.4 -71.3 265 47 24 0.7 0.4
40000 -57.0 -70.6 285 44 23 -0.0 -0.0 | -57.1 -70.8 275 45 23 0.2 0.1
38000 -55.9 -68.6 290 43 22 2.9 1.6 | -56.2 -69.2 275 45 23 2.6 1.4
36000 -54.2 -65.6 290 40 20 2.9 1.6 | -54.4 -65.9 280 44 23 2.6 1.4
34000 -51.7 -61.1 295 36 19 7.2 3.9 | -52.0 -61.6 280 43 22 7.4 4.1
32000 -47.3 -53.1 295 34 17 7.3 4.0 | -47.5 -53.5 280 38 20 7.5 4.1
30000 -42.9 -45.2 300 31 16 7.8 4.3 | -43.0 -45.4 280 35 18 7.9 4.3
29000 -40.6 -41.1 300 31 16 7.8 4.3 | -40.6 -41.1 275 35 18 7.9 4.3
28000 -38.2 -36.8 300 31 16 7.8 4.3 | -38.2 -36.8 275 34 18 7.9 4.3
27000 -35.9 -32.6 300 30 16 7.9 4.3 | -35.9 -32.6 275 34 18 7.6 4.2
26000 -33.5 -28.3 305 29 15 7.9 4.3 | -33.7 -28.7 275 32 17 7.4 4.1
25000 -31.2 -24.2 305 27 14 7.9 4.3 | -31.5 -24.7 280 31 16 7.4 4.1
24000 -28.8 -19.8 305 26 13 7.7 4.2 | -29.3 -20.7 280 29 15 7.3 4.0
23000 -26.2 -15.2 305 23 12 7.0 3.8 | -27.2 -17.0 280 27 14 7.0 3.9
22000 -24.1 -11.4 305 21 11 7.0 3.8 | -24.6 -12.3 285 25 13 7.0 3.9
21000 -22.0 -7.6 305 20 10 7.2 3.9 | -22.5 -8.5 290 24 12 6.9 3.8
20000 -19.9 -3.8 310 20 10 7.2 3.9 | -20.5 -4.9 295 22 11 6.9 3.8
19500 -18.8 -1.8 315 19 10 7.2 3.9 | -19.4 -2.9 295 22 11 6.9 3.8
19000 -17.8 -0.0 315 19 10 7.2 3.9 | -18.4 -1.1 300 21 11 6.9 3.8
18500 -16.7 1.9 320 19 10 7.1 3.9 | -17.3 0.9 300 20 10 7.4 4.1
18000 -15.6 3.9 320 20 10 7.0 3.9 | -16.2 2.8 300 20 10 7.4 4.1
17500 -14.6 5.7 320 20 10 6.9 3.8 | -15.1 4.8 305 19 10 7.4 4.0
17000 -13.6 7.5 325 20 10 6.8 3.7 | -14.0 6.8 305 19 10 7.3 4.0
16500 -12.6 9.3 325 19 10 6.8 3.7 | -12.9 8.8 310 18 9 7.3 4.0
16000 -11.6 11.1 325 19 10 5.7 3.1 | -11.9 10.6 310 18 9 6.5 3.6
15500 -10.8 12.6 325 19 10 5.8 3.2 | -10.9 12.4 310 17 9 6.7 3.7
15000 -10.0 14.0 330 18 9 5.3 2.9 | -10.0 14.0 315 16 8 5.8 3.2
14500 -9.2 15.4 325 17 9 5.2 2.9 | -9.1 15.6 315 16 8 5.7 3.1
14000 -8.4 16.9 325 16 8 5.0 2.7 | -8.3 17.1 315 15 8 5.2 2.9
13500 -7.7 18.1 325 15 8 4.8 2.7 | -7.6 18.3 310 14 7 5.0 2.8
13000 -7.0 19.4 325 13 7 4.8 2.6 | -6.8 19.8 310 13 7 5.0 2.7
12500 -6.4 20.5 325 12 6 4.7 2.6 | -6.1 21.0 310 12 6 4.9 2.7
12000 -5.7 21.7 325 10 5 4.9 2.7 | -5.4 22.3 305 10 5 4.9 2.7
11500 -5.0 23.0 325 8 4 5.1 2.8 | -4.7 23.5 305 9 5 5.0 2.7
11000 -4.2 24.4 325 7 4 5.4 3.0 | -4.0 24.8 300 7 4 5.2 2.8
10500 -3.4 25.9 325 6 3 5.7 3.1 | -3.2 26.2 300 6 3 5.5 3.0
10250 -3.0 26.6 320 5 3 5.9 3.2 | -2.8 27.0 295 5 3 5.1 2.8
10000 -2.6 27.3 325 4 2 5.5 3.0 | -2.5 27.5 300 5 2 4.7 2.6
9750 -2.2 28.0 325 4 2 4.9 2.7 | -2.1 28.2 295 4 2 5.3 2.9
9500 -1.9 28.6 325 3 2 4.9 2.7 | -1.8 28.8 290 4 2 5.4 3.0
9250 -1.5 29.3 315 3 1 5.2 2.9 | -1.4 29.5 280 3 2 5.5 3.0
9000 -1.1 30.0 315 2 1 5.8 3.2 | -1.0 30.2 275 3 2 5.4 3.0
8750 -0.8 30.6 320 1 1 4.5 2.5 | -0.7 30.7 270 3 1 4.3 2.3
8500 -0.5 31.1 305 1 0 3.6 2.0 | -0.4 31.3 265 2 1 4.0 2.2
8250 -0.1 31.8 000 0 0 2.9 1.6 | 0.0 32.0 240 2 1 1.5 0.8
8000 0.2 32.4 000 0 0 4.1 2.2 | 0.2 32.4 230 2 1 4.6 2.5
7750 0.5 32.9 180 1 0 5.1 2.8 | 0.6 33.1 225 2 1 6.9 3.8
7500 0.9 33.6 170 1 1 5.4 3.0 | 1.1 34.0 220 2 1 6.3 3.4
7250 1.3 34.3 170 1 1 5.6 3.1 | 1.5 34.7 215 2 1 4.9 2.7
7000 1.7 35.1 170 2 1 6.4 3.5 | 1.9 35.4 215 2 1 10.0 5.5
6750 2.2 36.0 165 2 1 6.6 3.6 | 2.9 37.2 215 2 1 11.7 6.4
6500 2.6 36.7 165 2 1 5.5 3.0 | 3.5 38.3 220 1 1 7.5 4.1
6250 3.1 37.6 160 2 1 6.5 3.5 | 4.1 39.4 230 1 1 7.4 4.1
6000 3.5 38.3 155 3 1 3.3 1.8 | 4.7 40.5 245 1 1 9.8 5.4
5750 3.4 38.1 160 2 1 -7.6 -4.2 | 5.6 42.1 240 1 1 17.0 9.3
5500 2.7 36.9 160 1 1 -10.2 -5.6 | 6.8 44.2 260 1 1 8.1 4.4
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
11/24/2025 at 1400 MST | 11/24/2025 at 1700 MST
|
CAPE... +0.4 LI... +3.6 | CAPE... 0.0 LI... +3.2
CINH... -0.0 K Index... +6.3 | CINH... 0.0 K Index... +14.9
|
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 -60.7 -77.3 260 42 22 2.1 1.1 | -60.5 -76.9 260 46 24 2.5 1.4
45000 -57.5 -71.5 260 51 26 0.1 0.1 | -56.8 -70.2 255 56 29 2.3 1.2
40000 -57.9 -72.2 260 51 26 -0.3 -0.2 | -57.1 -70.8 260 61 31 -0.3 -0.1
38000 -57.0 -70.6 265 52 27 3.1 1.7 | -56.4 -69.5 265 61 31 2.5 1.4
36000 -55.2 -67.4 270 53 27 3.1 1.7 | -54.9 -66.8 265 60 31 2.5 1.4
34000 -52.8 -63.0 275 53 27 8.0 4.4 | -53.1 -63.6 265 58 30 6.4 3.5
32000 -48.1 -54.6 270 48 25 7.8 4.3 | -49.4 -56.9 270 51 26 6.1 3.3
30000 -43.4 -46.1 270 43 22 7.4 4.1 | -45.6 -50.1 280 45 23 7.8 4.3
29000 -41.2 -42.2 275 41 21 7.4 4.1 | -43.3 -45.9 280 43 22 7.7 4.2
28000 -39.0 -38.2 275 40 21 7.4 4.1 | -41.0 -41.8 285 41 21 7.7 4.2
27000 -36.2 -33.2 275 38 20 7.4 4.1 | -38.7 -37.7 290 39 20 7.8 4.3
26000 -33.9 -29.0 280 37 19 7.4 4.1 | -35.6 -32.1 295 38 20 8.1 4.5
25000 -31.7 -25.1 280 36 19 7.4 4.1 | -33.2 -27.8 295 38 19 8.1 4.5
24000 -29.5 -21.1 285 35 18 7.0 3.9 | -30.7 -23.3 300 37 19 7.9 4.3
23000 -27.5 -17.5 285 33 17 6.8 3.7 | -28.4 -19.1 300 36 19 7.7 4.2
22000 -25.5 -13.9 285 32 16 6.8 3.7 | -26.1 -15.0 300 35 18 7.7 4.2
21000 -23.4 -10.1 285 30 16 7.1 3.9 | -23.8 -10.8 300 34 18 7.2 3.9
20000 -21.3 -6.3 285 29 15 7.1 3.9 | -21.7 -7.1 300 33 17 7.3 4.0
19500 -20.3 -4.5 290 28 14 7.1 3.9 | -20.6 -5.1 300 32 17 7.3 4.0
19000 -19.2 -2.6 290 27 14 7.1 3.9 | -19.5 -3.1 300 32 16 7.4 4.1
18500 -18.1 -0.6 290 27 14 7.4 4.1 | -18.5 -1.3 300 31 16 6.8 3.7
18000 -17.0 1.4 290 26 13 7.4 4.1 | -17.5 0.5 300 31 16 6.7 3.7
17500 -15.9 3.4 290 25 13 7.4 4.1 | -16.6 2.1 300 30 16 6.8 3.7
17000 -14.8 5.4 295 24 13 7.4 4.1 | -15.6 3.9 300 29 15 6.8 3.7
16500 -13.7 7.3 295 23 12 7.5 4.1 | -14.6 5.7 300 29 15 6.8 3.7
16000 -12.6 9.3 295 23 12 7.2 4.0 | -13.5 7.7 300 28 14 7.0 3.9
15500 -11.5 11.3 300 22 11 7.3 4.0 | -12.5 9.5 300 27 14 7.0 3.9
15000 -10.4 13.3 300 21 11 6.8 3.7 | -11.5 11.3 300 26 13 6.9 3.8
14500 -9.4 15.1 300 20 10 6.7 3.7 | -10.5 13.1 300 25 13 6.9 3.8
14000 -8.4 16.9 300 19 10 6.3 3.5 | -9.4 15.1 300 24 12 6.7 3.7
13500 -7.5 18.5 300 18 9 6.0 3.3 | -8.4 16.9 300 23 12 6.6 3.6
13000 -6.6 20.1 300 17 9 5.7 3.1 | -7.5 18.5 305 22 11 6.5 3.6
12500 -5.8 21.6 300 16 8 5.3 2.9 | -6.5 20.3 305 21 11 6.4 3.5
12000 -5.0 23.0 295 14 7 5.3 2.9 | -5.5 22.1 305 21 11 6.4 3.5
11500 -4.3 24.3 290 13 7 5.1 2.8 | -4.6 23.7 305 19 10 6.3 3.5
11000 -3.6 25.5 285 11 6 5.3 2.9 | -3.6 25.5 305 18 9 6.4 3.5
10500 -2.8 27.0 275 10 5 5.5 3.0 | -2.7 27.1 300 16 8 6.5 3.6
10250 -2.4 27.7 270 9 5 5.6 3.1 | -2.2 28.0 300 15 8 5.8 3.2
10000 -2.0 28.4 265 9 5 5.3 2.9 | -1.8 28.8 300 14 7 5.4 3.0
9750 -1.6 29.1 265 9 4 5.5 3.0 | -1.4 29.5 295 13 7 6.7 3.7
9500 -1.2 29.8 260 8 4 5.9 3.2 | -0.9 30.4 290 12 6 7.2 3.9
9250 -0.8 30.6 260 8 4 5.8 3.2 | -0.4 31.3 285 10 5 7.3 4.0
9000 0.0 32.0 250 7 4 5.7 3.1 | 0.7 33.3 275 10 5 6.7 3.7
8750 0.4 32.7 255 6 3 6.0 3.3 | 1.2 34.2 275 9 5 6.3 3.5
8500 0.8 33.4 255 5 3 4.8 2.6 | 1.6 34.9 270 8 4 5.9 3.2
8250 1.1 34.0 255 5 2 2.5 1.4 | 2.0 35.6 270 8 4 5.0 2.7
8000 1.3 34.3 260 4 2 5.9 3.2 | 2.3 36.1 270 8 4 5.2 2.8
7750 1.9 35.4 265 4 2 8.8 4.9 | 2.7 36.9 270 7 4 5.5 3.0
7500 2.4 36.3 275 3 2 6.5 3.5 | 3.0 37.4 275 6 3 4.6 2.5
7250 2.8 37.0 285 3 2 3.6 2.0 | 3.3 37.9 280 6 3 3.2 1.7
7000 3.2 37.8 290 3 2 10.2 5.6 | 3.6 38.5 285 5 3 6.1 3.3
6750 4.2 39.6 290 3 2 13.5 7.4 | 4.2 39.6 285 4 2 8.8 4.8
6500 5.0 41.0 290 3 2 9.1 5.0 | 4.8 40.6 295 4 2 8.0 4.4
6250 5.7 42.3 295 3 2 8.7 4.8 | 5.4 41.7 300 4 2 9.0 5.0
6000 6.3 43.3 300 3 2 10.6 5.8 | 6.0 42.8 310 4 2 6.0 3.3
5750 7.3 45.1 295 3 2 17.0 9.3 | 6.1 43.0 300 3 2 -3.1 -1.7
5500 8.7 47.7 305 3 2 17.2 9.4 | 5.8 42.4 315 3 2 -0.9 -0.5
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
________________________________________________________________________________
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 at Walker Field in Grand
Junction, Colorado at
North Latitude: 39 deg 07 min 00.001 sec
West Longitude: 108 deg 31 min 59.998 sec
Elevation: 4839 feet (1475 meters)
and may not be representative of other areas along the Western Slope of
Colorado. 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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