Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
418
UXUS97 KGJT 261306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Wednesday, November 26, 2025
This forecast is for Wednesday, November 26, 2025:
If the trigger temperature of 52.8 F/11.5 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 261 ft/min (1.3 m/s)
Maximum height of thermals.................. 9137 ft MSL (3529 ft AGL)
Forecast maximum temperature................... 51.0 F/11.0 C
Time of trigger temperature.................... None
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................. 7249 ft MSL (1642 ft AGL)
Thermal soaring outlook for Thursday 11/27..... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:09:52 / 16:53:19 MST
Total possible sunshine........... 9 hr 43 min 27 sec (583 min 27 sec)
Altitude of sun at 12:01:35 MST... 29.79 degrees
Upper air data from rawinsonde observation taken on 11/26/2025 at 0500 MST
Freezing level.................. 5622 ft MSL (14 ft AGL)
Additional freezing level....... 9111 ft MSL (3503 ft AGL)
Convective condensation level... 19686 ft MSL (14078 ft AGL)
Lifted condensation level....... 13227 ft MSL (7619 ft AGL)
Lifted index.................... +12.9
K index......................... +6.1
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 -67.1 -88.8 295 50 26 -1.7 -1.0 M M M M M
45000 -69.6 -93.3 285 53 27 1.1 0.6 M M M M M
40000 -65.7 -86.3 290 37 19 2.3 1.2 M M M M M
38000 -61.4 -78.5 285 39 20 8.5 4.6 M M M M M
36000 -56.3 -69.3 275 42 22 8.5 4.6 M M M M M
34000 -51.1 -60.0 275 46 24 8.8 4.8 M M M M M
32000 -45.8 -50.4 270 50 26 8.8 4.8 M M M M M
30000 -40.5 -40.9 275 52 27 8.7 4.8 34.7 94.5 18.3 M M
29000 -37.9 -36.2 275 52 27 8.7 4.8 34.3 93.7 18.2 M M
28000 -35.2 -31.4 280 52 27 8.7 4.8 34.0 93.2 18.2 M M
27000 -32.6 -26.7 280 51 26 9.0 4.9 33.7 92.6 18.1 M M
26000 -29.9 -21.8 285 48 25 9.0 4.9 33.3 91.9 18.1 M M
25000 -27.2 -17.0 285 45 23 9.0 4.9 33.1 91.5 18.1 M M
24000 -24.6 -12.3 290 43 22 6.7 3.7 32.6 90.7 17.9 M M
23000 -22.6 -8.7 290 42 22 7.0 3.8 31.5 88.7 17.2 M M
22000 -19.9 -3.8 290 40 21 7.0 3.8 30.3 86.6 16.5 M M
21000 -17.8 -0.0 295 40 20 7.3 4.0 29.4 84.9 15.8 M M
20000 -15.7 3.7 295 39 20 7.3 4.0 28.5 83.3 15.2 M M
19500 -14.6 5.7 295 39 20 7.3 4.0 28.1 82.6 14.9 M M
19000 -13.5 7.7 300 38 20 6.3 3.5 27.7 81.9 14.6 M M
18500 -12.7 9.1 300 38 19 5.6 3.1 27.0 80.5 14.0 M M
18000 -11.9 10.6 300 37 19 5.6 3.1 26.2 79.2 13.5 M M
17500 -11.2 11.8 300 35 18 4.9 2.7 25.5 77.8 12.8 M M
17000 -10.5 13.1 305 33 17 5.0 2.7 24.7 76.4 12.1 M M
16500 -9.7 14.5 305 32 16 5.7 3.1 23.9 75.0 11.5 M M
16000 -8.8 16.2 310 30 15 5.9 3.2 23.2 73.8 11.0 M M
15500 -8.0 17.6 310 28 14 5.9 3.2 22.6 72.7 10.5 M M
15000 -7.1 19.2 315 26 13 5.9 3.2 21.9 71.5 9.9 M M
14500 -6.2 20.8 315 25 13 5.9 3.2 21.3 70.3 9.4 M M
14000 -5.3 22.5 315 23 12 6.1 3.4 20.7 69.2 8.9 M M
13500 -4.4 24.1 315 22 11 6.2 3.4 20.1 68.2 8.4 M M
13000 -3.6 25.5 315 20 10 5.0 2.7 19.4 66.9 7.8 M M
12500 -2.8 27.0 310 18 9 5.3 2.9 18.6 65.6 7.2 M M
12000 -2.1 28.2 310 17 9 2.9 1.6 17.7 63.9 6.4 M M
11500 -1.6 29.1 305 15 8 3.3 1.8 16.7 62.0 5.4 M M
11000 -1.3 29.7 300 13 7 1.5 0.8 15.5 59.9 4.3 M M
10500 -1.1 30.0 295 10 5 1.0 0.5 14.2 57.6 3.1 M M
10250 -1.1 30.0 290 9 5 0.9 0.5 13.5 56.3 2.4 M M
10000 -0.9 30.4 285 8 4 2.9 1.6 12.9 55.2 1.8 M M
9750 -0.7 30.7 280 7 4 3.6 2.0 12.4 54.3 1.3 M M
9500 -0.4 31.3 275 6 3 3.2 1.8 11.9 53.4 0.8 M M
9250 -0.2 31.6 270 5 3 3.1 1.7 11.4 52.5 0.3 M M
9000 0.1 32.2 265 4 2 4.2 2.3 10.9 51.6 -0.1 256 1.3
8750 0.4 32.7 255 4 2 4.9 2.7 10.5 50.9 -0.5 238 1.2
8500 0.8 33.4 245 3 2 4.6 2.5 10.1 50.2 -0.9 220 1.1
8250 1.1 34.0 230 3 1 4.6 2.5 9.7 49.5 -1.3 202 1.0
8000 1.5 34.7 210 3 1 4.3 2.4 9.3 48.7 -1.7 184 0.9
7750 1.8 35.2 195 3 1 4.1 2.3 8.9 48.0 -2.1 167 0.8
7500 2.1 35.8 175 3 1 4.6 2.5 8.4 47.2 -2.5 150 0.8
7250 2.5 36.5 165 4 2 4.8 2.7 8.1 46.5 -2.9 131 0.7
7000 2.8 37.0 155 4 2 4.9 2.7 7.7 45.9 -3.2 113 0.6
6750 3.2 37.8 150 4 2 2.2 1.2 7.3 45.1 -3.7 96 0.5
6500 3.2 37.8 145 4 2 -0.5 -0.3 6.5 43.8 -4.4 88 0.4
6250 3.2 37.8 135 5 2 0.9 0.5 5.8 42.5 -5.1 81 0.4
6000 3.2 37.8 130 5 3 -3.0 -1.7 5.1 41.1 -5.9 73 0.4
5750 2.4 36.3 125 5 2 -20.7 -11.4 3.5 38.4 -7.4 90 0.5
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 * * * * * *
11/26/2025 at 0800 MST | 11/26/2025 at 1100 MST
|
CAPE... 0.0 LI... +9.9 | CAPE... 0.0 LI... +8.1
CINH... -0.1 K Index... +4.6 | CINH... -0.0 K Index... +2.9
|
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 -63.8 -82.8 295 45 23 -0.1 -0.0 | -64.1 -83.4 295 45 23 -0.1 -0.1
45000 -63.9 -83.0 295 58 30 -0.2 -0.1 | -64.3 -83.7 300 59 30 -0.5 -0.3
40000 -64.8 -84.6 310 86 44 -0.6 -0.3 | -66.1 -87.0 310 83 43 -1.2 -0.7
38000 -62.6 -80.7 315 94 48 7.3 4.0 | -63.5 -82.3 315 88 45 8.2 4.5
36000 -57.6 -71.7 320 100 51 7.3 4.0 | -58.0 -72.4 315 88 45 8.2 4.5
34000 -52.9 -63.2 325 103 53 8.7 4.8 | -52.9 -63.2 320 88 45 9.0 4.9
32000 -47.7 -53.9 325 102 52 8.7 4.8 | -47.5 -53.5 315 90 46 9.0 4.9
30000 -42.7 -44.9 325 97 50 7.8 4.3 | -42.0 -43.6 315 92 47 9.3 5.1
29000 -40.4 -40.7 320 91 47 7.8 4.3 | -39.2 -38.6 315 93 48 9.3 5.1
28000 -38.1 -36.6 320 86 44 7.8 4.3 | -36.4 -33.5 315 94 48 9.4 5.1
27000 -35.7 -32.3 320 80 41 7.7 4.2 | -33.7 -28.7 315 94 48 7.8 4.3
26000 -33.4 -28.1 320 75 38 7.7 4.2 | -31.3 -24.3 315 91 47 8.0 4.4
25000 -31.1 -24.0 315 69 35 7.7 4.2 | -28.9 -20.0 315 89 46 8.0 4.4
24000 -28.8 -19.8 315 63 33 8.0 4.4 | -26.6 -15.9 320 86 44 6.5 3.6
23000 -25.8 -14.4 315 60 31 8.1 4.4 | -24.8 -12.6 320 79 41 6.1 3.4
22000 -23.4 -10.1 310 58 30 8.1 4.4 | -22.5 -8.5 320 71 37 6.1 3.4
21000 -21.0 -5.8 310 56 29 7.9 4.3 | -20.6 -5.1 320 65 33 6.9 3.8
20000 -18.6 -1.5 310 53 27 7.9 4.3 | -18.5 -1.3 315 59 30 6.9 3.8
19500 -17.5 0.5 310 52 27 7.9 4.3 | -17.5 0.5 315 56 29 6.9 3.8
19000 -16.3 2.7 310 51 26 7.8 4.3 | -16.4 2.5 310 53 27 7.0 3.9
18500 -15.2 4.6 310 49 25 6.9 3.8 | -15.4 4.3 310 52 27 7.5 4.1
18000 -14.2 6.4 310 47 24 7.0 3.8 | -14.3 6.3 310 51 26 7.5 4.1
17500 -13.3 8.1 310 45 23 5.7 3.2 | -13.2 8.2 310 49 25 6.9 3.8
17000 -12.5 9.5 310 43 22 5.4 3.0 | -12.2 10.0 310 48 25 6.8 3.7
16500 -11.7 10.9 310 41 21 5.0 2.7 | -11.2 11.8 310 47 24 6.2 3.4
16000 -11.1 12.0 310 38 20 3.9 2.2 | -10.5 13.1 310 45 23 5.1 2.8
15500 -10.5 13.1 305 36 18 4.0 2.2 | -9.7 14.5 310 42 22 5.0 2.8
15000 -10.0 14.0 305 33 17 3.3 1.8 | -9.1 15.6 310 40 21 3.2 1.7
14500 -9.5 14.9 300 31 16 3.4 1.8 | -8.7 16.3 310 37 19 3.4 1.9
14000 -8.9 16.0 300 29 15 3.8 2.1 | -8.2 17.2 310 34 18 2.7 1.5
13500 -8.3 17.1 295 26 14 3.8 2.1 | -7.8 18.0 305 31 16 2.7 1.5
13000 -7.7 18.1 295 24 12 4.4 2.4 | -7.4 18.7 305 29 15 3.6 2.0
12500 -7.0 19.4 290 22 11 4.5 2.5 | -6.8 19.8 300 26 14 3.6 2.0
12000 -6.3 20.7 285 20 10 4.3 2.4 | -6.2 20.8 300 24 12 4.6 2.5
11500 -5.7 21.7 280 18 9 4.2 2.3 | -5.5 22.1 295 22 11 4.8 2.6
11000 -5.0 23.0 275 16 8 4.6 2.5 | -4.8 23.4 290 20 10 5.1 2.8
10500 -4.4 24.1 270 14 7 4.6 2.5 | -4.0 24.8 285 18 9 5.2 2.9
10250 -4.0 24.8 265 13 7 5.0 2.7 | -3.6 25.5 285 17 9 4.7 2.6
10000 -3.6 25.5 265 12 6 5.6 3.1 | -3.2 26.2 280 16 8 4.6 2.5
9750 -3.2 26.2 265 11 6 5.7 3.1 | -2.9 26.8 280 15 8 5.2 2.8
9500 -2.8 27.0 260 11 5 5.7 3.1 | -2.5 27.5 275 13 7 5.1 2.8
9250 -2.4 27.7 255 10 5 5.9 3.2 | -2.1 28.2 270 12 6 5.6 3.0
9000 -2.0 28.4 250 10 5 6.1 3.4 | -1.7 28.9 265 12 6 5.9 3.3
8750 -1.5 29.3 250 9 5 6.2 3.4 | -1.2 29.8 265 11 6 5.9 3.2
8500 -0.6 30.9 235 7 4 5.6 3.1 | -0.8 30.6 260 10 5 5.7 3.1
8250 -0.2 31.6 230 7 4 5.4 3.0 | -0.4 31.3 260 9 5 5.4 3.0
8000 0.2 32.4 225 7 3 5.6 3.1 | 0.4 32.7 255 8 4 7.7 4.2
7750 0.6 33.1 215 6 3 5.6 3.1 | 1.0 33.8 250 6 3 6.9 3.8
7500 1.0 33.8 205 6 3 5.4 3.0 | 1.3 34.3 250 5 3 4.1 2.3
7250 1.4 34.5 195 6 3 5.6 3.1 | 1.6 34.9 255 4 2 3.1 1.7
7000 1.8 35.2 185 6 3 5.1 2.8 | 1.9 35.4 255 3 2 9.4 5.1
6750 2.1 35.8 180 5 3 4.5 2.5 | 2.9 37.2 245 3 1 11.8 6.5
6500 2.5 36.5 175 5 2 4.5 2.5 | 3.5 38.3 245 2 1 8.1 4.4
6250 2.8 37.0 165 5 2 4.6 2.5 | 4.1 39.4 240 2 1 6.2 3.4
6000 2.9 37.2 155 5 3 -5.4 -2.9 | 4.5 40.1 250 1 1 8.0 4.4
5750 1.8 35.2 145 5 2 -21.9 -12.0 | 5.6 42.1 255 1 1 21.6 11.8
5500 0.8 33.4 125 4 2 7.6 4.2 | 6.8 44.2 260 1 1 -3.6 -2.0
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
11/26/2025 at 1400 MST | 11/26/2025 at 1700 MST
|
CAPE... 0.0 LI... +8.1 | CAPE... 0.0 LI... +7.8
CINH... -0.4 K Index... +4.8 | CINH... -0.2 K Index... +5.2
|
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 -63.5 -82.3 295 48 25 -0.4 -0.2 | -64.3 -83.7 300 50 26 -0.5 -0.3
45000 -64.0 -83.2 300 63 32 -0.8 -0.4 | -65.1 -85.2 310 64 33 -0.7 -0.4
40000 -66.3 -87.3 320 79 41 -1.6 -0.9 | -66.5 -87.7 315 71 37 -1.0 -0.6
38000 -62.9 -81.2 325 83 43 8.9 4.9 | -62.7 -80.9 315 74 38 8.9 4.9
36000 -57.6 -71.7 325 83 43 8.9 4.9 | -57.4 -71.3 310 77 40 8.9 4.9
34000 -52.2 -62.0 325 83 43 9.0 4.9 | -52.0 -61.6 310 78 40 9.2 5.0
32000 -46.9 -52.4 320 81 42 9.0 4.9 | -46.5 -51.7 315 76 39 9.2 5.0
30000 -41.5 -42.7 320 79 41 8.8 4.9 | -41.1 -42.0 315 75 39 8.9 4.9
29000 -38.9 -38.0 315 79 40 8.9 4.9 | -38.4 -37.1 315 75 39 8.9 4.9
28000 -36.2 -33.2 315 78 40 8.9 4.9 | -35.8 -32.4 315 75 39 8.9 4.9
27000 -33.6 -28.5 315 78 40 8.4 4.6 | -33.1 -27.6 315 74 38 8.6 4.7
26000 -31.1 -24.0 315 77 40 8.4 4.6 | -30.6 -23.1 310 73 38 8.6 4.7
25000 -28.6 -19.5 310 77 40 8.5 4.6 | -28.0 -18.4 310 72 37 8.6 4.7
24000 -26.1 -15.0 310 77 40 7.9 4.3 | -25.5 -13.9 310 71 36 7.7 4.2
23000 -23.2 -9.8 310 76 39 7.8 4.3 | -22.6 -8.7 315 71 36 7.7 4.2
22000 -20.9 -5.6 310 76 39 7.7 4.2 | -20.3 -4.5 315 71 36 7.7 4.2
21000 -18.9 -2.0 310 72 37 5.7 3.1 | -18.3 -0.9 315 69 35 6.0 3.3
20000 -17.2 1.0 315 66 34 5.6 3.1 | -16.5 2.3 315 65 33 5.9 3.3
19500 -16.4 2.5 315 64 33 5.6 3.1 | -15.7 3.7 320 63 32 5.9 3.3
19000 -15.5 4.1 315 61 31 5.5 3.0 | -14.8 5.4 320 61 31 5.7 3.1
18500 -14.8 5.4 315 57 29 4.9 2.7 | -14.0 6.8 320 58 30 5.0 2.7
18000 -14.1 6.6 315 54 28 4.9 2.7 | -13.3 8.1 320 56 29 5.0 2.8
17500 -13.3 8.1 315 51 26 5.5 3.0 | -12.5 9.5 320 53 27 4.5 2.5
17000 -12.5 9.5 315 48 25 5.6 3.1 | -11.9 10.6 320 50 26 4.5 2.4
16500 -11.7 10.9 315 45 23 5.8 3.2 | -11.2 11.8 320 47 24 4.5 2.4
16000 -10.8 12.6 310 43 22 6.0 3.3 | -10.6 12.9 320 43 22 4.5 2.5
15500 -9.9 14.2 310 41 21 6.0 3.3 | -9.9 14.2 315 40 21 4.6 2.5
15000 -9.2 15.4 310 39 20 4.7 2.6 | -9.2 15.4 315 37 19 5.1 2.8
14500 -8.5 16.7 310 36 19 5.0 2.7 | -8.5 16.7 315 34 17 5.1 2.8
14000 -7.9 17.8 310 34 17 3.5 1.9 | -7.8 18.0 315 31 16 5.1 2.8
13500 -7.3 18.9 310 31 16 3.6 2.0 | -7.0 19.4 315 28 15 5.1 2.8
13000 -6.8 19.8 310 29 15 3.9 2.1 | -6.3 20.7 315 26 13 4.9 2.7
12500 -6.2 20.8 305 26 14 3.8 2.1 | -5.6 21.9 315 24 12 4.8 2.7
12000 -5.6 21.9 305 24 12 4.9 2.7 | -4.8 23.4 310 21 11 5.2 2.9
11500 -4.8 23.4 300 22 11 5.0 2.7 | -4.0 24.8 310 20 10 5.2 2.9
11000 -4.0 24.8 295 20 10 5.4 3.0 | -3.3 26.1 305 18 9 5.4 3.0
10500 -3.2 26.2 290 17 9 5.4 2.9 | -2.4 27.7 300 16 8 5.4 3.0
10250 -2.8 27.0 285 16 8 6.1 3.3 | -2.0 28.4 300 16 8 5.5 3.0
10000 -2.3 27.9 285 16 8 6.0 3.3 | -1.6 29.1 295 15 8 5.7 3.1
9750 -1.9 28.6 280 15 8 5.2 2.8 | -1.2 29.8 290 14 7 5.9 3.3
9500 -1.5 29.3 275 13 7 5.0 2.8 | -0.7 30.7 285 12 6 5.8 3.2
9250 -1.1 30.0 275 12 6 6.2 3.4 | -0.2 31.6 280 11 6 6.9 3.8
9000 -0.6 30.9 270 12 6 7.0 3.8 | 0.3 32.5 270 11 6 7.4 4.1
8750 -0.1 31.8 265 11 6 5.7 3.1 | 0.8 33.4 265 11 6 5.6 3.1
8500 0.3 32.5 265 9 5 5.4 3.0 | 1.2 34.2 265 10 5 5.2 2.8
8250 1.1 34.0 265 8 4 5.5 3.0 | 2.1 35.8 265 9 4 6.1 3.3
8000 1.6 34.9 270 7 4 9.2 5.0 | 2.5 36.5 265 8 4 6.9 3.8
7750 2.4 36.3 270 6 3 8.7 4.7 | 3.0 37.4 265 6 3 5.9 3.3
7500 2.8 37.0 275 5 3 5.3 2.9 | 3.4 38.1 270 6 3 4.6 2.6
7250 3.2 37.8 280 5 3 4.5 2.5 | 3.7 38.7 280 5 3 4.4 2.4
7000 3.6 38.5 290 5 2 10.1 5.5 | 4.1 39.4 290 4 2 6.5 3.6
6750 4.6 40.3 285 4 2 12.5 6.8 | 4.7 40.5 290 3 2 8.1 4.4
6500 5.3 41.5 285 4 2 9.2 5.0 | 5.2 41.4 295 3 1 6.6 3.6
6250 6.0 42.8 290 4 2 7.9 4.4 | 5.7 42.3 305 2 1 8.1 4.4
6000 6.6 43.9 300 4 2 9.9 5.4 | 6.2 43.2 330 3 1 2.8 1.5
5750 7.7 45.9 300 4 2 20.9 11.5 | 6.0 42.8 340 3 1 -9.1 -5.0
5500 8.9 48.0 305 4 2 0.2 0.1 | 5.7 42.3 350 2 1 12.0 6.6
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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