Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
358
UXUS97 KGJT 161306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Thursday, October 16, 2025
This forecast is for Thursday, October 16, 2025:
If the trigger temperature of 51.9 F/11.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 561 ft/min (2.9 m/s)
Maximum height of thermals.................. 12961 ft MSL (7354 ft AGL)
Forecast maximum temperature................... 60.0 F/16.0 C
Time of trigger temperature.................... 1030 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................. 10969 ft MSL (5363 ft AGL)
Thermal soaring outlook for Friday 10/17....... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:25:24 / 18:33:42 MDT
Total possible sunshine........... 11 hr 8 min 18 sec (668 min 18 sec)
Altitude of sun at 12:59:33 MDT... 41.69 degrees
Upper air data from rawinsonde observation taken on 10/16/2025 at 0600 MDT
Freezing level.................. 9195 ft MSL (3588 ft AGL)
Convective condensation level... 15601 ft MSL (9994 ft AGL)
Lifted condensation level....... 14509 ft MSL (8903 ft AGL)
Lifted index.................... +3.0
K index......................... +8.7
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 -59.1 -74.4 255 23 12 2.6 1.4 M M M M M
45000 -55.0 -67.0 245 29 15 3.8 2.1 M M M M M
40000 -49.3 -56.7 245 36 19 3.8 2.1 M M M M M
38000 -47.4 -53.3 245 42 21 2.9 1.6 M M M M M
36000 -45.7 -50.3 245 48 25 2.9 1.6 M M M M M
34000 -43.6 -46.5 240 56 29 3.4 1.9 M M M M M
32000 -41.6 -42.9 240 63 32 3.4 1.9 M M M M M
30000 -39.2 -38.6 240 66 34 5.0 2.8 37.2 98.9 16.3 M M
29000 -37.7 -35.9 240 63 32 5.1 2.8 35.2 95.4 15.0 M M
28000 -36.2 -33.2 240 59 31 5.1 2.8 33.4 92.1 13.8 M M
27000 -34.7 -30.5 245 56 29 4.9 2.7 31.8 89.2 12.7 M M
26000 -33.3 -27.9 245 47 24 4.8 2.6 29.7 85.5 11.2 M M
25000 -31.8 -25.2 250 37 19 4.8 2.6 27.9 82.1 9.9 M M
24000 -30.4 -22.7 255 27 14 5.3 2.9 26.1 79.0 8.6 M M
23000 -28.3 -18.9 265 23 12 7.4 4.0 25.0 77.1 7.8 M M
22000 -26.1 -15.0 270 20 10 7.4 4.0 24.2 75.5 7.1 M M
21000 -23.9 -11.0 280 18 9 7.9 4.4 23.4 74.2 6.6 M M
20000 -21.4 -6.5 280 18 9 8.3 4.5 22.8 73.1 6.1 M M
19500 -19.5 -3.1 285 18 9 8.3 4.5 22.5 72.4 5.9 M M
19000 -18.3 -0.9 285 18 9 8.4 4.6 22.2 72.0 5.7 M M
18500 -17.2 1.0 285 18 9 6.9 3.8 21.9 71.4 5.4 M M
18000 -16.1 3.0 280 18 9 6.9 3.8 21.4 70.5 5.0 M M
17500 -15.1 4.8 280 18 9 6.8 3.8 21.0 69.7 4.6 M M
17000 -14.1 6.6 280 18 9 6.7 3.7 20.4 68.8 4.2 M M
16500 -13.1 8.4 275 18 9 6.7 3.7 19.9 67.8 3.7 M M
16000 -12.2 10.0 275 18 9 6.7 3.7 19.4 66.9 3.2 M M
15500 -11.2 11.8 275 18 9 6.7 3.7 18.9 66.0 2.8 M M
15000 -10.2 13.6 275 17 9 6.4 3.5 18.3 65.0 2.3 M M
14500 -9.3 15.3 280 17 9 6.4 3.5 17.8 64.0 1.8 M M
14000 -8.3 17.1 280 16 8 5.9 3.2 17.2 63.0 1.3 M M
13500 -7.5 18.5 280 15 8 5.7 3.1 16.5 61.7 0.7 M M
13000 -6.7 19.9 280 14 7 5.3 2.9 15.9 60.6 0.0 M M
12500 -5.9 21.4 280 13 6 5.1 2.8 15.1 59.2 -0.7 527 2.7
12000 -5.2 22.6 285 11 6 5.1 2.8 14.4 57.8 -1.4 490 2.5
11500 -4.5 23.9 285 9 5 5.2 2.8 13.6 56.5 -2.2 454 2.3
11000 -3.8 25.2 285 8 4 5.7 3.1 12.9 55.2 -2.9 417 2.1
10500 -2.9 26.8 280 6 3 6.1 3.3 12.3 54.2 -3.5 375 1.9
10250 -2.4 27.7 280 6 3 7.7 4.2 12.1 53.7 -3.8 353 1.8
10000 -1.8 28.8 280 5 3 7.8 4.3 12.0 53.5 -3.9 328 1.7
9750 -1.3 29.7 280 5 2 6.7 3.7 11.7 53.1 -4.1 305 1.6
9500 -0.7 30.7 275 4 2 6.9 3.8 11.5 52.7 -4.4 282 1.4
9250 -0.2 31.6 270 3 2 7.1 3.9 11.3 52.3 -4.6 259 1.3
9000 0.3 32.5 275 3 1 7.7 4.2 11.1 52.0 -4.8 236 1.2
8750 0.9 33.6 270 2 1 7.7 4.2 11.0 51.7 -5.0 211 1.1
8500 1.5 34.7 265 2 1 8.0 4.4 10.8 51.4 -5.1 186 0.9
8250 2.1 35.8 255 2 1 6.7 3.7 10.6 51.2 -5.3 161 0.8
8000 2.5 36.5 240 1 1 6.0 3.3 10.3 50.6 -5.6 140 0.7
7750 3.0 37.4 220 1 1 6.9 3.8 10.1 50.2 -5.8 118 0.6
7500 3.5 38.3 200 1 1 6.6 3.6 9.9 49.8 -6.1 96 0.5
7250 4.0 39.2 175 1 1 5.5 3.0 9.6 49.3 -6.3 74 0.4
7000 4.4 39.9 155 2 1 5.3 2.9 9.3 48.7 -6.7 55 0.3
6750 4.8 40.6 145 2 1 6.6 3.6 9.0 48.1 -7.0 35 0.2
6500 5.3 41.5 140 2 1 4.2 2.3 8.7 47.6 -7.3 14 0.1
6250 5.4 41.7 130 3 1 -0.7 -0.4 8.1 46.5 -7.9 3 0.0
6000 5.4 41.7 125 3 2 5.1 2.8 7.4 45.3 -8.7 M M
5750 5.8 42.4 125 3 2 0.8 0.4 7.1 44.8 -9.0 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 * * * * * *
10/16/2025 at 0900 MDT | 10/16/2025 at 1200 MDT
|
CAPE... +0.4 LI... +4.7 | CAPE... +9.9 LI... +3.3
CINH... -5.8 K Index... +4.3 | CINH... -1.0 K Index... +4.9
|
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 -60.0 -76.0 230 38 20 2.2 1.2 | -59.8 -75.6 230 36 19 2.0 1.1
45000 -56.3 -69.3 240 55 28 4.8 2.6 | -56.2 -69.2 235 53 27 4.8 2.6
40000 -48.7 -55.7 230 66 34 4.8 2.6 | -48.6 -55.5 230 67 34 4.8 2.6
38000 -45.5 -49.9 230 70 36 5.5 3.0 | -45.5 -49.9 230 70 36 5.4 3.0
36000 -42.2 -44.0 230 74 38 5.5 3.0 | -42.2 -44.0 230 73 38 5.4 3.0
34000 -39.0 -38.2 230 78 40 5.3 2.9 | -39.4 -38.9 230 75 39 3.6 2.0
32000 -35.8 -32.4 225 81 42 5.3 2.9 | -37.2 -35.0 230 75 38 3.6 2.0
30000 -32.9 -27.2 225 83 43 2.8 1.5 | -34.6 -30.3 230 74 38 6.6 3.6
29000 -32.1 -25.8 225 81 42 2.8 1.5 | -32.6 -26.7 230 74 38 6.7 3.7
28000 -31.2 -24.2 225 79 41 2.8 1.5 | -30.6 -23.1 230 74 38 6.7 3.7
27000 -30.4 -22.7 225 77 40 2.7 1.5 | -28.6 -19.5 230 74 38 5.4 2.9
26000 -30.5 -22.9 225 72 37 -1.1 -0.6 | -28.3 -18.9 230 68 35 -0.1 -0.1
25000 -30.8 -23.4 225 65 33 -1.1 -0.6 | -28.4 -19.1 230 62 32 -0.1 -0.1
24000 -31.3 -24.3 230 57 29 1.4 0.7 | -28.4 -19.1 230 53 28 1.2 0.7
23000 -29.3 -20.7 230 54 28 7.4 4.0 | -27.4 -17.3 230 49 25 3.7 2.0
22000 -27.1 -16.8 230 52 27 7.3 4.0 | -26.3 -15.3 230 45 23 3.7 2.0
21000 -24.9 -12.8 230 50 26 8.1 4.4 | -25.0 -13.0 230 41 21 7.0 3.9
20000 -22.4 -8.3 230 48 25 8.3 4.5 | -22.7 -8.9 230 40 20 7.9 4.3
19500 -21.2 -6.2 230 47 24 8.3 4.5 | -21.5 -6.7 230 39 20 7.9 4.3
19000 -19.9 -3.8 230 46 24 8.3 4.5 | -20.3 -4.5 230 38 20 7.9 4.3
18500 -18.7 -1.7 235 45 23 7.9 4.3 | -19.2 -2.6 230 37 19 8.0 4.4
18000 -17.6 0.3 235 43 22 7.5 4.1 | -18.0 -0.4 230 36 19 8.0 4.4
17500 -16.4 2.5 235 42 21 7.5 4.1 | -16.8 1.8 235 35 18 7.9 4.4
17000 -15.4 4.3 235 40 21 6.7 3.6 | -15.7 3.7 235 34 17 7.0 3.9
16500 -14.4 6.1 235 38 20 6.8 3.7 | -14.6 5.7 235 32 16 7.2 3.9
16000 -13.4 7.9 235 36 19 6.1 3.4 | -13.6 7.5 235 30 16 5.8 3.2
15500 -12.5 9.5 240 34 18 6.0 3.3 | -12.8 9.0 235 29 15 5.6 3.1
15000 -11.6 11.1 240 33 17 5.4 2.9 | -12.0 10.4 235 27 14 5.2 2.9
14500 -10.9 12.4 240 31 16 4.8 2.6 | -11.3 11.7 240 25 13 5.0 2.7
14000 -10.2 13.6 240 29 15 4.6 2.5 | -10.5 13.1 240 23 12 5.0 2.8
13500 -9.6 14.7 240 27 14 4.4 2.4 | -9.8 14.4 245 22 11 5.2 2.8
13000 -9.6 14.7 245 25 13 4.5 2.5 | -9.0 15.8 245 20 10 5.2 2.8
12500 -8.3 17.1 245 23 12 5.1 2.8 | -8.3 17.1 245 18 9 5.3 2.9
12000 -7.5 18.5 245 21 11 5.2 2.8 | -7.5 18.5 250 16 8 5.5 3.0
11500 -6.7 19.9 245 19 10 5.9 3.2 | -6.7 19.9 250 15 7 6.4 3.5
11000 -5.9 21.4 240 18 9 5.9 3.2 | -5.8 21.6 245 13 7 6.5 3.5
10500 -5.0 23.0 240 17 9 6.2 3.4 | -4.8 23.4 245 12 6 6.9 3.8
10250 -4.6 23.7 240 16 8 5.6 3.1 | -4.3 24.3 245 11 6 6.6 3.6
10000 -4.1 24.6 240 16 8 7.6 4.2 | -3.8 25.2 245 11 6 9.1 5.0
9750 -3.5 25.7 240 15 8 8.4 4.6 | -3.0 26.6 245 10 5 9.6 5.3
9500 -3.0 26.6 235 14 7 7.1 3.9 | -2.4 27.7 245 10 5 7.8 4.3
9250 -2.4 27.7 235 14 7 7.2 4.0 | -1.8 28.8 245 10 5 8.3 4.6
9000 -1.9 28.6 235 13 7 8.1 4.4 | -1.2 29.8 245 9 5 7.9 4.3
8750 -1.3 29.7 235 13 7 8.4 4.6 | -0.6 30.9 245 9 4 8.4 4.6
8500 -0.1 31.8 235 12 6 7.8 4.3 | 0.0 32.0 245 8 4 9.2 5.1
8250 0.4 32.7 235 12 6 7.5 4.1 | 1.3 34.3 250 7 4 7.0 3.8
8000 1.0 33.8 235 12 6 8.3 4.6 | 1.8 35.2 250 7 4 8.8 4.8
7750 1.7 35.1 235 11 6 9.5 5.2 | 2.6 36.7 255 7 4 11.2 6.1
7500 2.3 36.1 235 10 5 8.1 4.5 | 3.3 37.9 255 7 3 9.3 5.1
7250 2.9 37.2 240 10 5 6.2 3.4 | 4.0 39.2 260 6 3 7.4 4.1
7000 3.4 38.1 240 10 5 8.2 4.5 | 4.6 40.3 265 6 3 10.2 5.6
6750 4.0 39.2 240 8 4 9.5 5.2 | 5.4 41.7 260 6 3 12.2 6.7
6500 4.6 40.3 245 7 3 7.2 3.9 | 6.3 43.3 260 6 3 10.3 5.7
6250 5.1 41.2 255 6 3 6.3 3.5 | 7.0 44.6 265 6 3 10.3 5.7
6000 5.6 42.1 265 5 2 6.8 3.7 | 7.8 46.0 270 6 3 9.0 5.0
5750 6.1 43.0 250 4 2 8.7 4.8 | 8.5 47.3 260 6 3 12.6 6.9
5500 6.9 44.4 285 2 1 16.5 9.1 | 10.5 50.9 275 5 3 54.1 29.7
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
10/16/2025 at 1500 MDT | 10/16/2025 at 1800 MDT
|
CAPE... +32.2 LI... +1.8 | CAPE... +26.6 LI... +2.4
CINH... -2.2 K Index... +8.4 | CINH... -11.8 K Index... +7.1
|
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 -59.9 -75.8 230 37 19 2.0 1.1 | -59.6 -75.3 240 32 17 2.1 1.1
45000 -56.4 -69.5 235 55 28 4.7 2.6 | -56.1 -69.0 240 49 25 4.6 2.5
40000 -49.3 -56.7 235 62 32 4.8 2.6 | -49.2 -56.6 235 59 31 4.6 2.5
38000 -46.0 -50.8 230 67 34 4.9 2.7 | -46.4 -51.5 235 66 34 3.9 2.1
36000 -43.1 -45.6 230 72 37 4.9 2.7 | -44.1 -47.4 235 72 37 3.9 2.1
34000 -40.4 -40.7 230 75 38 3.4 1.9 | -41.7 -43.1 230 76 39 4.1 2.3
32000 -38.4 -37.1 230 74 38 3.4 1.9 | -39.2 -38.6 235 75 39 4.1 2.3
30000 -35.8 -32.4 230 73 38 6.4 3.5 | -36.5 -33.7 235 74 38 5.6 3.1
29000 -33.9 -29.0 230 73 38 6.5 3.6 | -34.8 -30.6 235 73 37 5.6 3.1
28000 -31.9 -25.4 235 73 38 6.5 3.6 | -33.2 -27.8 235 71 37 5.6 3.1
27000 -30.0 -22.0 235 73 38 5.8 3.2 | -31.5 -24.7 240 70 36 5.3 2.9
26000 -28.6 -19.5 235 69 36 4.4 2.4 | -30.0 -22.0 240 65 33 4.8 2.6
25000 -27.3 -17.1 235 65 33 4.4 2.4 | -28.6 -19.5 240 59 31 4.8 2.6
24000 -26.0 -14.8 235 60 31 4.7 2.6 | -27.2 -17.0 245 54 28 4.9 2.7
23000 -25.0 -13.0 240 51 26 2.1 1.1 | -26.1 -15.0 250 42 21 2.6 1.4
22000 -24.4 -11.9 240 43 22 2.0 1.1 | -25.3 -13.5 255 31 16 2.6 1.4
21000 -23.7 -10.7 240 35 18 4.9 2.7 | -24.2 -11.6 270 23 12 7.2 3.9
20000 -22.1 -7.8 245 30 16 5.5 3.0 | -22.1 -7.8 275 21 11 7.3 4.0
19500 -21.2 -6.2 245 28 15 5.5 3.0 | -21.0 -5.8 275 21 11 7.3 4.0
19000 -20.4 -4.7 245 26 13 5.5 3.0 | -19.9 -3.8 280 20 10 7.3 4.0
18500 -19.6 -3.3 245 24 12 6.2 3.4 | -18.8 -1.8 285 19 10 7.4 4.1
18000 -18.6 -1.5 250 23 12 6.6 3.6 | -17.7 0.1 285 19 10 7.4 4.1
17500 -17.7 0.1 250 23 12 6.6 3.6 | -16.6 2.1 285 18 9 7.3 4.0
17000 -16.7 1.9 255 22 11 6.4 3.5 | -15.6 3.9 285 17 9 6.6 3.6
16500 -15.8 3.6 255 21 11 6.5 3.5 | -14.6 5.7 285 17 9 6.7 3.7
16000 -14.8 5.4 255 21 11 6.3 3.5 | -13.7 7.3 285 16 8 6.1 3.3
15500 -13.9 7.0 260 20 10 6.3 3.5 | -12.8 9.0 285 15 8 6.1 3.4
15000 -13.0 8.6 260 19 10 6.6 3.6 | -11.9 10.6 285 14 7 5.9 3.3
14500 -12.0 10.4 260 18 9 6.8 3.7 | -11.0 12.2 285 13 7 5.9 3.3
14000 -11.0 12.2 255 17 9 7.0 3.8 | -10.2 13.6 280 13 7 6.4 3.5
13500 -9.9 14.2 255 16 8 7.2 3.9 | -9.2 15.4 275 12 6 6.9 3.8
13000 -8.9 16.0 250 15 8 7.2 4.0 | -8.2 17.2 275 11 6 7.2 4.0
12500 -7.8 18.0 250 14 7 7.3 4.0 | -7.1 19.2 270 11 6 7.9 4.3
12000 -6.7 19.9 250 13 7 7.5 4.1 | -5.9 21.4 270 10 5 8.0 4.4
11500 -5.6 21.9 250 12 6 8.1 4.4 | -4.7 23.5 270 9 5 8.4 4.6
11000 -4.4 24.1 250 11 6 7.9 4.3 | -3.5 25.7 265 9 5 8.2 4.5
10500 -3.3 26.1 250 11 6 7.4 4.1 | -2.3 27.9 265 9 5 7.6 4.2
10250 -2.7 27.1 250 11 6 8.3 4.5 | -1.7 28.9 265 9 5 8.4 4.6
10000 -2.0 28.4 250 10 5 10.0 5.5 | -1.0 30.2 265 9 4 9.0 4.9
9750 -1.3 29.7 250 10 5 9.1 5.0 | -0.4 31.3 270 8 4 7.9 4.4
9500 -0.7 30.7 255 9 5 8.1 4.4 | 0.1 32.2 270 8 4 7.6 4.2
9250 -0.1 31.8 255 9 5 8.3 4.6 | 0.7 33.3 270 8 4 7.8 4.3
9000 0.5 32.9 260 8 4 8.2 4.5 | 1.3 34.3 275 9 4 8.5 4.7
8750 1.1 34.0 260 8 4 8.4 4.6 | 2.0 35.6 275 9 5 8.0 4.4
8500 1.8 35.2 265 8 4 8.7 4.8 | 3.1 37.6 280 8 4 7.2 4.0
8250 3.0 37.4 275 7 4 7.2 3.9 | 3.6 38.5 285 8 4 6.6 3.6
8000 3.5 38.3 280 7 3 9.2 5.1 | 4.1 39.4 290 8 4 7.8 4.3
7750 4.3 39.7 280 7 3 11.7 6.4 | 4.7 40.5 295 8 4 9.1 5.0
7500 5.1 41.2 280 7 3 8.9 4.9 | 5.4 41.7 300 7 4 7.9 4.3
7250 5.6 42.1 290 7 3 5.7 3.2 | 5.9 42.6 305 7 4 6.5 3.6
7000 6.2 43.2 295 7 3 10.4 5.7 | 6.4 43.5 305 7 4 9.4 5.2
6750 7.2 45.0 290 7 3 13.4 7.3 | 7.2 45.0 310 7 4 11.2 6.1
6500 8.0 46.4 290 7 3 10.2 5.6 | 7.9 46.2 310 7 3 9.0 5.0
6250 8.7 47.7 295 7 3 9.6 5.3 | 8.6 47.5 315 7 3 8.5 4.7
6000 9.4 48.9 305 7 3 8.9 4.9 | 9.2 48.6 320 7 3 8.6 4.7
5750 10.2 50.4 290 6 3 12.9 7.1 | 9.8 49.6 315 6 3 8.4 4.6
5500 12.2 54.0 305 6 3 51.1 28.0 | 10.4 50.7 325 5 3 9.6 5.3
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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