Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
506
UXUS97 KGJT 041306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Tuesday, November 4, 2025
This forecast is for Tuesday, November 4, 2025:
If the trigger temperature of 64.4 F/18.0 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 404 ft/min (2.1 m/s)
Maximum height of thermals.................. 10930 ft MSL (5322 ft AGL)
Forecast maximum temperature................... 67.0 F/19.9 C
Time of trigger temperature.................... 1200 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................. 7983 ft MSL (2375 ft AGL)
Thermal soaring outlook for Wednesday 11/05.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:45:40 / 17:09:39 MST
Total possible sunshine........... 10 hr 23 min 59 sec (623 min 59 sec)
Altitude of sun at 11:57:40 MST... 35.26 degrees
Upper air data from rawinsonde observation taken on 11/04/2025 at 0500 MST
Freezing level.................. 13337 ft MSL (7729 ft AGL)
Convective condensation level... 19816 ft MSL (14208 ft AGL)
Lifted condensation level....... 16275 ft MSL (10667 ft AGL)
Lifted index.................... +7.7
K index......................... -4.6
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 -64.9 -84.8 260 54 28 1.8 1.0 M M M M M
45000 -62.0 -79.6 260 55 28 2.7 1.5 M M M M M
40000 -58.0 -72.4 260 49 25 2.6 1.4 M M M M M
38000 -54.7 -66.5 255 44 23 5.2 2.9 M M M M M
36000 -51.5 -60.7 255 39 20 5.2 2.9 M M M M M
34000 -47.1 -52.8 255 34 18 8.4 4.6 M M M M M
32000 -42.1 -43.8 250 31 16 8.5 4.6 M M M M M
30000 -37.0 -34.6 245 28 14 8.4 4.6 38.0 100.4 14.0 M M
29000 -34.5 -30.1 245 27 14 8.4 4.6 37.5 99.4 13.8 M M
28000 -32.0 -25.6 245 26 14 8.4 4.6 37.1 98.7 13.7 M M
27000 -29.4 -20.9 245 26 14 8.6 4.7 36.6 97.8 13.4 M M
26000 -26.8 -16.2 250 27 14 8.6 4.7 36.1 96.9 13.2 M M
25000 -24.3 -11.7 250 27 14 8.5 4.7 35.7 96.3 13.1 M M
24000 -22.1 -7.8 250 26 14 6.0 3.3 34.8 94.7 12.5 M M
23000 -20.3 -4.5 255 25 13 5.9 3.3 33.4 92.0 11.4 M M
22000 -18.5 -1.3 255 24 12 5.9 3.3 32.0 89.7 10.4 M M
21000 -16.1 3.0 255 23 12 6.7 3.7 30.5 87.0 9.3 M M
20000 -14.1 6.6 255 23 12 6.7 3.7 29.5 85.1 8.5 M M
19500 -13.1 8.4 255 23 12 6.7 3.7 29.0 84.2 8.1 M M
19000 -12.1 10.2 255 23 12 7.6 4.2 28.6 83.4 7.7 M M
18500 -10.9 12.4 255 24 12 7.6 4.2 28.2 82.7 7.4 M M
18000 -9.8 14.4 255 24 12 7.8 4.3 27.8 82.1 7.2 M M
17500 -8.6 16.5 255 24 12 8.3 4.5 27.5 81.6 7.0 M M
17000 -7.3 18.9 255 24 12 8.3 4.6 27.3 81.1 6.8 M M
16500 -6.1 21.0 255 23 12 7.7 4.2 27.0 80.6 6.6 M M
16000 -5.0 23.0 255 23 12 7.8 4.3 26.6 80.0 6.3 M M
15500 -3.8 25.2 255 22 11 7.1 3.9 26.3 79.3 6.0 M M
15000 -2.8 27.0 255 21 11 6.8 3.7 25.8 78.4 5.6 M M
14500 -1.8 28.8 255 20 10 6.2 3.4 25.3 77.6 5.2 M M
14000 -1.0 30.2 250 19 10 5.2 2.8 24.6 76.2 4.5 M M
13500 -0.2 31.6 245 17 9 5.1 2.8 23.8 74.9 3.9 M M
13000 0.5 32.9 240 16 8 4.7 2.6 23.0 73.5 3.1 M M
12500 1.1 34.0 235 15 8 4.8 2.6 22.2 72.0 2.3 M M
12000 1.8 35.2 230 14 7 4.8 2.7 21.4 70.6 1.5 M M
11500 2.5 36.5 230 14 7 4.9 2.7 20.6 69.2 0.8 M M
11000 3.3 37.9 225 13 7 6.1 3.3 20.0 67.9 0.1 M M
10500 4.2 39.6 225 12 6 5.7 3.1 19.4 66.9 -0.5 371 1.9
10250 4.6 40.3 220 11 6 6.3 3.4 19.1 66.3 -0.8 351 1.8
10000 5.1 41.2 215 11 5 7.1 3.9 18.8 65.9 -1.0 328 1.7
9750 5.6 42.1 210 10 5 6.9 3.8 18.6 65.5 -1.2 306 1.6
9500 6.1 43.0 205 10 5 6.9 3.8 18.4 65.1 -1.5 283 1.4
9250 6.6 43.9 200 9 5 7.0 3.8 18.2 64.7 -1.7 260 1.3
9000 7.2 45.0 190 9 5 7.1 3.9 18.0 64.3 -1.9 237 1.2
8750 7.7 45.9 185 9 5 7.2 4.0 17.8 64.0 -2.1 214 1.1
8500 8.2 46.8 180 10 5 6.8 3.7 17.6 63.6 -2.3 190 1.0
8250 8.7 47.7 175 11 5 6.0 3.3 17.3 63.1 -2.6 169 0.9
8000 9.1 48.4 175 11 6 5.5 3.0 17.0 62.6 -2.9 149 0.8
7750 9.5 49.1 170 12 6 5.3 2.9 16.6 62.0 -3.2 129 0.7
7500 9.9 49.8 165 12 6 3.7 2.0 16.3 61.3 -3.6 111 0.6
7250 10.0 50.0 160 13 6 1.9 1.0 15.7 60.3 -4.2 98 0.5
7000 10.2 50.4 155 13 7 4.0 2.2 15.2 59.3 -4.7 85 0.4
6750 10.5 50.9 155 13 7 1.4 0.8 14.7 58.5 -5.2 70 0.4
6500 10.4 50.7 150 12 6 -4.0 -2.2 13.8 56.9 -6.1 67 0.3
6250 10.0 50.0 145 10 5 -5.9 -3.3 12.7 54.9 -7.2 70 0.4
6000 9.6 49.3 140 9 5 -1.7 -0.9 11.6 52.9 -8.3 74 0.4
5750 9.3 48.7 130 8 4 -13.3 -7.3 10.6 51.1 -9.3 75 0.4
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 * * * * * *
11/04/2025 at 0800 MST | 11/04/2025 at 1100 MST
|
CAPE... 0.0 LI... +8.0 | CAPE... 0.0 LI... +8.1
CINH... -0.2 K Index... -8.9 | CINH... -0.0 K Index... -6.8
|
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 -65.4 -85.7 265 44 23 3.1 1.7 | -65.3 -85.5 265 49 25 3.1 1.7
45000 -60.4 -76.7 260 48 25 4.6 2.5 | -60.4 -76.7 260 55 28 4.0 2.2
40000 -53.1 -63.6 260 51 26 3.3 1.8 | -54.0 -65.2 260 58 30 3.9 2.1
38000 -51.7 -61.1 260 48 25 2.4 1.3 | -51.8 -61.2 265 46 24 3.7 2.0
36000 -50.3 -58.5 260 45 23 2.3 1.3 | -49.6 -57.3 270 35 18 3.7 2.0
34000 -47.1 -52.8 260 45 23 7.1 3.9 | -46.5 -51.7 270 30 16 6.2 3.4
32000 -42.9 -45.2 255 47 24 7.1 3.9 | -42.8 -45.0 265 30 16 6.1 3.4
30000 -38.0 -36.4 255 46 24 8.9 4.9 | -38.2 -36.8 265 32 16 8.7 4.8
29000 -35.3 -31.5 255 44 23 8.9 4.9 | -35.6 -32.1 260 33 17 8.7 4.8
28000 -32.7 -26.9 255 42 22 9.0 4.9 | -33.0 -27.4 260 34 18 8.7 4.8
27000 -30.2 -22.4 255 41 21 7.9 4.4 | -30.5 -22.9 260 35 18 8.1 4.4
26000 -27.8 -18.0 255 41 21 7.9 4.4 | -28.1 -18.6 260 36 19 8.1 4.4
25000 -24.9 -12.8 255 40 21 7.9 4.4 | -25.7 -14.3 260 37 19 8.1 4.4
24000 -22.5 -8.5 255 40 21 8.0 4.4 | -22.7 -8.9 260 38 20 7.9 4.3
23000 -20.0 -4.0 255 40 21 8.0 4.4 | -20.3 -4.5 260 39 20 7.9 4.3
22000 -17.6 0.3 255 40 21 8.1 4.5 | -18.0 -0.4 260 40 21 8.0 4.4
21000 -15.4 4.3 255 39 20 7.1 3.9 | -15.7 3.7 260 39 20 7.5 4.1
20000 -13.3 8.1 260 37 19 7.1 3.9 | -13.4 7.9 260 38 19 7.5 4.1
19500 -12.2 10.0 260 36 19 7.1 3.9 | -12.3 9.9 260 37 19 7.5 4.1
19000 -11.1 12.0 260 36 18 6.8 3.8 | -11.2 11.8 260 36 18 6.8 3.7
18500 -10.1 13.8 260 34 18 6.7 3.7 | -10.2 13.6 260 34 18 6.6 3.6
18000 -9.1 15.6 260 33 17 6.7 3.7 | -9.2 15.4 260 33 17 6.6 3.6
17500 -8.1 17.4 260 32 16 6.4 3.5 | -8.2 17.2 260 31 16 6.2 3.4
17000 -7.2 19.0 260 30 16 6.4 3.5 | -7.3 18.9 260 30 15 6.3 3.4
16500 -6.2 20.8 260 29 15 6.2 3.4 | -6.4 20.5 260 29 15 6.1 3.3
16000 -5.3 22.5 260 28 14 6.1 3.3 | -5.5 22.1 260 27 14 6.0 3.3
15500 -4.4 24.1 260 26 14 5.7 3.1 | -4.6 23.7 260 26 13 5.7 3.1
15000 -3.6 25.5 260 25 13 5.1 2.8 | -3.8 25.2 260 25 13 5.3 2.9
14500 -2.9 26.8 255 24 12 5.1 2.8 | -3.0 26.6 260 24 12 5.2 2.9
14000 -2.2 28.0 255 23 12 4.9 2.7 | -2.3 27.9 255 23 12 4.5 2.5
13500 -1.5 29.3 255 22 11 4.9 2.7 | -1.6 29.1 255 22 11 4.6 2.5
13000 -0.7 30.7 250 21 11 5.3 2.9 | -0.9 30.4 250 21 11 5.4 2.9
12500 0.0 32.0 250 21 11 5.2 2.9 | -0.1 31.8 250 21 11 5.2 2.9
12000 0.9 33.6 245 21 11 6.3 3.5 | 0.7 33.3 245 20 10 6.1 3.3
11500 1.8 35.2 245 20 10 6.2 3.4 | 1.5 34.7 245 19 10 5.9 3.2
11000 2.8 37.0 245 20 10 7.0 3.8 | 2.5 36.5 245 19 10 6.9 3.8
10500 3.8 38.8 240 19 10 7.6 4.2 | 3.5 38.3 240 18 9 7.2 3.9
10250 4.3 39.7 240 19 10 4.5 2.5 | 4.0 39.2 240 18 9 5.5 3.0
10000 4.5 40.1 240 19 10 4.9 2.7 | 4.3 39.7 240 18 9 6.0 3.3
9750 5.1 41.2 235 18 9 8.1 4.5 | 4.9 40.8 240 17 9 7.9 4.3
9500 5.6 42.1 235 17 9 7.5 4.1 | 5.4 41.7 240 17 9 7.4 4.1
9250 6.1 43.0 230 16 8 5.4 3.0 | 5.9 42.6 235 16 8 6.0 3.3
9000 6.4 43.5 230 15 8 4.6 2.5 | 6.3 43.3 235 16 8 5.6 3.1
8750 7.4 45.3 220 13 7 6.4 3.5 | 6.8 44.2 235 15 7 6.9 3.8
8500 7.8 46.0 220 12 6 5.1 2.8 | 7.3 45.1 235 13 7 6.4 3.5
8250 8.1 46.6 210 10 5 4.5 2.5 | 8.1 46.6 230 10 5 5.0 2.7
8000 8.5 47.3 205 9 5 4.6 2.5 | 8.5 47.3 230 9 5 7.2 3.9
7750 8.8 47.8 200 9 4 4.8 2.7 | 9.1 48.4 225 8 4 6.7 3.7
7500 9.2 48.6 190 8 4 5.1 2.8 | 9.5 49.1 220 7 3 4.9 2.7
7250 9.6 49.3 180 8 4 5.6 3.1 | 9.9 49.8 220 5 3 5.0 2.7
7000 9.9 49.8 175 8 4 2.4 1.3 | 10.3 50.5 210 4 2 9.2 5.0
6750 9.9 49.8 170 7 4 0.2 0.1 | 11.1 52.0 210 4 2 10.2 5.6
6500 10.0 50.0 165 7 4 0.7 0.4 | 11.8 53.2 205 4 2 7.9 4.3
6250 10.1 50.2 155 7 4 2.6 1.4 | 12.4 54.3 205 3 2 7.9 4.3
6000 10.1 50.2 150 7 4 -5.5 -3.0 | 13.0 55.4 200 3 1 11.9 6.6
5750 8.9 48.0 130 4 2 -27.8 -15.2 | 14.3 57.7 205 3 1 20.9 11.5
5500 7.2 45.0 100 3 2 -2.6 -1.4 | 15.4 59.7 205 2 1 2.0 1.1
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
11/04/2025 at 1400 MST | 11/04/2025 at 1700 MST
|
CAPE... 0.0 LI... +7.3 | CAPE... 0.0 LI... +6.2
CINH... -0.3 K Index... -6.0 | CINH... -0.0 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 -65.5 -85.9 265 55 28 2.8 1.5 | -65.4 -85.7 265 56 29 2.5 1.4
45000 -61.0 -77.8 265 60 31 4.0 2.2 | -61.5 -78.7 265 59 31 3.3 1.8
40000 -55.1 -67.2 265 59 30 4.0 2.2 | -56.6 -69.9 270 55 28 3.2 1.8
38000 -52.5 -62.5 270 45 23 3.8 2.1 | -53.6 -64.5 270 44 22 4.5 2.5
36000 -50.2 -58.4 280 32 16 3.8 2.1 | -50.9 -59.6 275 33 17 4.5 2.5
34000 -46.5 -51.7 285 27 14 7.7 4.2 | -46.7 -52.1 280 28 14 8.5 4.6
32000 -41.9 -43.4 290 26 13 7.7 4.2 | -41.6 -42.9 285 27 14 8.5 4.6
30000 -37.2 -35.0 285 26 14 8.0 4.4 | -36.5 -33.7 285 27 14 8.4 4.6
29000 -34.8 -30.6 280 27 14 8.0 4.4 | -34.0 -29.2 285 28 14 8.4 4.6
28000 -32.4 -26.3 275 28 14 8.0 4.4 | -31.5 -24.7 285 28 14 8.5 4.6
27000 -30.0 -22.0 275 30 15 7.7 4.2 | -29.2 -20.6 280 29 15 7.6 4.1
26000 -27.7 -17.9 270 31 16 7.7 4.2 | -26.9 -16.4 280 29 15 7.5 4.1
25000 -25.4 -13.7 265 33 17 7.7 4.2 | -24.6 -12.3 275 30 16 7.5 4.1
24000 -22.6 -8.7 265 35 18 7.3 4.0 | -22.0 -7.6 270 32 16 6.5 3.6
23000 -20.4 -4.7 260 37 19 7.3 4.0 | -20.1 -4.2 270 33 17 6.5 3.6
22000 -18.2 -0.8 260 38 20 7.3 4.0 | -18.1 -0.6 270 35 18 6.5 3.5
21000 -15.9 3.4 260 39 20 7.9 4.3 | -16.1 3.0 270 35 18 7.0 3.8
20000 -13.5 7.7 260 39 20 7.9 4.3 | -14.0 6.8 270 34 17 7.0 3.8
19500 -12.4 9.7 260 39 20 7.9 4.3 | -12.9 8.8 270 34 17 7.0 3.8
19000 -11.2 11.8 260 39 20 7.3 4.0 | -11.9 10.6 270 33 17 7.1 3.9
18500 -10.1 13.8 265 38 19 7.1 3.9 | -10.8 12.6 270 32 17 7.2 3.9
18000 -9.1 15.6 265 36 19 7.0 3.9 | -9.8 14.4 270 32 16 7.1 3.9
17500 -8.1 17.4 265 34 18 6.6 3.6 | -8.7 16.3 270 30 16 6.6 3.6
17000 -7.1 19.2 265 33 17 6.6 3.6 | -7.8 18.0 270 29 15 6.7 3.7
16500 -6.1 21.0 265 31 16 6.3 3.5 | -6.8 19.8 270 28 15 6.7 3.7
16000 -5.1 22.8 265 29 15 6.3 3.4 | -5.8 21.6 270 27 14 6.7 3.7
15500 -4.2 24.4 265 28 14 6.0 3.3 | -4.8 23.4 270 26 13 6.4 3.5
15000 -3.4 25.9 260 26 14 5.6 3.1 | -3.8 25.2 270 25 13 6.1 3.4
14500 -2.5 27.5 260 25 13 5.5 3.0 | -2.9 26.8 270 24 12 6.1 3.4
14000 -1.8 28.8 260 24 12 4.7 2.6 | -2.0 28.4 265 23 12 6.1 3.4
13500 -1.1 30.0 260 23 12 4.8 2.6 | -1.1 30.0 265 22 11 6.1 3.4
13000 -0.4 31.3 255 22 11 5.3 2.9 | -0.2 31.6 260 21 11 6.2 3.4
12500 0.4 32.7 250 21 11 5.2 2.8 | 0.7 33.3 255 20 10 6.2 3.4
12000 1.2 34.2 245 20 10 6.5 3.6 | 1.6 34.9 250 19 10 6.8 3.7
11500 2.2 36.0 245 19 10 6.4 3.5 | 2.6 36.7 245 18 9 6.7 3.7
11000 3.1 37.6 240 18 9 7.2 4.0 | 3.6 38.5 240 17 9 7.5 4.1
10500 4.2 39.6 235 17 9 7.6 4.2 | 4.7 40.5 235 16 8 7.8 4.3
10250 4.7 40.5 235 16 8 5.5 3.0 | 5.2 41.4 235 15 8 6.2 3.4
10000 5.1 41.2 235 16 8 6.6 3.6 | 5.7 42.3 235 16 8 6.8 3.8
9750 5.7 42.3 235 16 8 9.3 5.1 | 6.3 43.3 235 15 8 8.8 4.8
9500 6.4 43.5 235 15 8 8.8 4.8 | 6.9 44.4 230 14 7 8.4 4.6
9250 7.0 44.6 235 14 7 7.1 3.9 | 7.5 45.5 230 13 7 7.9 4.3
9000 7.4 45.3 235 13 7 6.7 3.7 | 8.0 46.4 230 12 6 7.1 3.9
8750 8.0 46.4 235 12 6 8.4 4.6 | 9.1 48.4 230 11 6 7.0 3.8
8500 8.6 47.5 235 11 6 7.7 4.2 | 9.6 49.3 235 10 5 5.4 2.9
8250 9.5 49.1 240 9 5 5.3 2.9 | 9.9 49.8 235 9 5 5.2 2.9
8000 10.0 50.0 245 8 4 9.8 5.4 | 10.4 50.7 240 8 4 8.0 4.4
7750 10.8 51.4 245 7 4 8.7 4.8 | 11.0 51.8 245 7 4 7.2 3.9
7500 11.2 52.2 255 7 3 5.1 2.8 | 11.4 52.5 255 6 3 4.6 2.5
7250 11.6 52.9 265 6 3 5.2 2.9 | 11.8 53.2 265 5 3 4.5 2.5
7000 12.2 54.0 275 5 3 12.4 6.8 | 12.2 54.0 275 4 2 7.6 4.2
6750 13.3 55.9 265 6 3 12.4 6.8 | 12.8 55.0 290 4 2 8.5 4.6
6500 13.9 57.0 275 5 3 7.4 4.1 | 13.3 55.9 305 4 2 6.2 3.4
6250 14.5 58.1 285 5 3 8.1 4.4 | 13.8 56.8 320 4 2 8.2 4.5
6000 15.2 59.4 295 5 3 12.2 6.7 | 14.4 57.9 330 4 2 2.4 1.3
5750 16.5 61.7 285 5 2 21.9 12.0 | 14.0 57.2 325 3 2 -12.0 -6.6
5500 17.6 63.7 300 5 2 0.1 0.1 | 13.4 56.1 340 3 2 6.4 3.5
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.
042613