Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
209
UXUS97 KGJT 141306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Tuesday, October 14, 2025
This forecast is for Tuesday, October 14, 2025:
If the trigger temperature of 64.5 F/18.0 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 737 ft/min (3.7 m/s)
Maximum height of thermals.................. 14363 ft MSL (8756 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 1100 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................. 11238 ft MSL (5631 ft AGL)
Thermal soaring outlook for Wednesday 10/15.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:23:23 / 18:36:36 MDT
Total possible sunshine........... 11 hr 13 min 13 sec (673 min 13 sec)
Altitude of sun at 13:00:00 MDT... 42.43 degrees
Upper air data from rawinsonde observation taken on 10/14/2025 at 0600 MDT
Freezing level.................. 12287 ft MSL (6680 ft AGL)
Convective condensation level... 11514 ft MSL (5907 ft AGL)
Lifted condensation level....... 12725 ft MSL (7118 ft AGL)
Lifted index.................... -0.3
K index......................... +18.6
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 -62.6 -80.7 210 52 27 3.0 1.7 M M M M M
45000 -57.9 -72.2 215 79 41 3.4 1.9 M M M M M
40000 -52.8 -63.0 210 99 51 3.7 2.0 M M M M M
38000 -49.8 -57.6 210 99 51 5.1 2.8 M M M M M
36000 -46.4 -51.5 210 99 51 5.0 2.8 M M M M M
34000 -43.0 -45.4 210 97 50 6.0 3.3 M M M M M
32000 -39.4 -38.9 210 93 48 6.0 3.3 M M M M M
30000 -35.3 -31.5 210 89 46 7.6 4.2 40.0 104.1 13.5 M M
29000 -33.0 -27.4 210 86 45 7.6 4.2 39.2 102.5 13.0 M M
28000 -30.7 -23.3 210 84 43 7.6 4.2 38.4 101.2 12.6 M M
27000 -28.4 -19.1 210 82 42 7.9 4.3 37.7 99.8 12.2 M M
26000 -26.0 -14.8 205 81 42 7.9 4.3 36.9 98.5 11.7 M M
25000 -23.6 -10.5 205 80 41 7.9 4.3 36.3 97.3 11.3 M M
24000 -21.4 -6.5 205 79 41 6.8 3.7 35.6 96.0 10.9 M M
23000 -19.3 -2.7 210 76 39 6.9 3.8 34.4 94.0 10.0 M M
22000 -17.2 1.0 210 74 38 6.9 3.8 33.4 92.2 9.3 M M
21000 -15.3 4.5 210 71 37 5.6 3.1 32.3 90.1 8.4 M M
20000 -13.2 8.2 205 67 34 5.7 3.1 30.5 86.8 6.9 M M
19500 -12.4 9.7 205 65 33 5.7 3.2 29.8 85.6 6.4 M M
19000 -11.5 11.3 205 63 33 5.8 3.2 29.2 84.5 5.9 M M
18500 -10.7 12.7 205 61 32 5.9 3.2 28.5 83.2 5.3 M M
18000 -9.8 14.4 205 59 30 5.9 3.2 27.8 82.0 4.7 M M
17500 -8.9 16.0 205 57 29 5.6 3.1 27.1 80.8 4.1 M M
17000 -8.1 17.4 200 56 29 5.6 3.1 26.4 79.5 3.5 M M
16500 -7.3 18.9 200 54 28 5.3 2.9 25.7 78.3 2.9 M M
16000 -6.6 20.1 200 52 27 5.1 2.8 24.9 76.9 2.2 M M
15500 -5.9 21.4 200 50 26 5.2 2.9 24.1 75.5 1.4 M M
15000 -5.1 22.8 195 49 25 6.2 3.4 23.5 74.3 0.7 M M
14500 -4.2 24.4 195 48 25 6.2 3.4 22.9 73.2 0.1 M M
14000 -3.3 26.1 195 47 24 6.6 3.6 22.3 72.2 -0.5 705 3.6
13500 -2.4 27.7 190 46 24 6.6 3.6 21.8 71.3 -1.0 662 3.4
13000 -1.5 29.3 190 46 24 7.2 4.0 21.4 70.4 -1.5 619 3.1
12500 -0.4 31.3 190 45 23 7.3 4.0 21.0 69.7 -2.0 573 2.9
12000 0.6 33.1 185 45 23 7.6 4.2 20.6 69.1 -2.4 527 2.7
11500 1.7 35.1 185 43 22 7.7 4.2 20.2 68.4 -2.8 480 2.4
11000 2.7 36.9 185 41 21 7.5 4.1 19.9 67.8 -3.2 433 2.2
10500 3.8 38.8 185 38 20 8.4 4.6 19.5 67.2 -3.6 386 2.0
10250 4.5 40.1 185 37 19 9.7 5.3 19.5 67.1 -3.6 359 1.8
10000 5.1 41.2 185 36 18 8.5 4.6 19.5 67.0 -3.7 332 1.7
9750 5.7 42.3 185 34 18 7.8 4.3 19.3 66.8 -3.9 307 1.6
9500 6.3 43.3 185 33 17 8.0 4.4 19.2 66.5 -4.0 282 1.4
9250 6.9 44.4 185 32 16 8.2 4.5 19.1 66.3 -4.2 257 1.3
9000 7.5 45.5 185 30 15 7.9 4.3 18.9 66.1 -4.4 232 1.2
8750 8.0 46.4 185 28 14 7.5 4.1 18.7 65.7 -4.5 208 1.1
8500 8.6 47.5 185 26 14 7.5 4.1 18.6 65.4 -4.7 184 0.9
8250 9.2 48.6 185 25 13 7.7 4.2 18.4 65.2 -4.9 160 0.8
8000 9.7 49.5 185 23 12 7.3 4.0 18.3 64.9 -5.1 135 0.7
7750 10.2 50.4 185 21 11 6.7 3.7 18.0 64.5 -5.3 112 0.6
7500 10.7 51.3 180 19 10 6.9 3.8 17.8 64.1 -5.5 90 0.5
7250 11.2 52.2 180 17 9 6.2 3.4 17.6 63.6 -5.8 68 0.3
7000 11.7 53.1 175 16 8 5.5 3.0 17.3 63.1 -6.1 48 0.2
6750 12.1 53.8 170 14 7 6.0 3.3 17.0 62.5 -6.4 28 0.1
6500 12.5 54.5 165 12 6 4.3 2.4 16.6 62.0 -6.8 8 0.0
6250 12.6 54.7 160 11 5 0.0 0.0 16.1 60.9 -7.3 M M
6000 12.7 54.9 155 10 5 3.6 2.0 15.4 59.7 -8.0 M M
5750 13.0 55.4 145 8 4 -1.3 -0.7 14.9 58.9 -8.5 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 * * * * * *
10/14/2025 at 0900 MDT | 10/14/2025 at 1200 MDT
|
CAPE... +124.3 LI... -1.5 | CAPE... +456.1 LI... -2.0
CINH... -34.1 K Index... +28.7 | CINH... -3.7 K Index... +25.7
|
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 -82.3 215 68 35 1.3 0.7 | -63.3 -81.9 215 69 35 1.3 0.7
45000 -60.3 -76.5 215 100 52 5.5 3.0 | -60.1 -76.2 215 99 51 5.6 3.1
40000 -51.9 -61.4 220 113 58 5.7 3.1 | -51.6 -60.9 215 113 58 5.6 3.1
38000 -48.4 -55.1 215 116 60 6.0 3.3 | -47.9 -54.2 215 113 58 5.4 3.0
36000 -44.3 -47.7 215 119 61 6.0 3.3 | -44.7 -48.5 215 114 59 5.4 3.0
34000 -40.6 -41.1 215 115 59 6.4 3.5 | -41.1 -42.0 215 109 56 6.5 3.5
32000 -36.8 -34.2 215 108 56 6.4 3.5 | -37.2 -35.0 215 100 51 6.5 3.6
30000 -33.8 -28.8 215 93 48 3.8 2.1 | -33.9 -29.0 220 88 45 4.7 2.6
29000 -32.7 -26.9 215 82 42 3.8 2.1 | -32.5 -26.5 220 81 42 4.7 2.6
28000 -31.6 -24.9 215 71 37 4.0 2.2 | -31.1 -24.0 220 74 38 4.8 2.6
27000 -29.9 -21.8 215 63 33 7.1 3.9 | -29.4 -20.9 220 69 35 6.9 3.8
26000 -27.8 -18.0 215 60 31 7.2 3.9 | -27.3 -17.1 220 65 33 7.0 3.8
25000 -25.7 -14.3 215 56 29 7.2 3.9 | -25.2 -13.4 220 61 31 7.0 3.8
24000 -23.5 -10.3 215 53 27 7.2 4.0 | -23.1 -9.6 220 58 30 7.0 3.9
23000 -20.9 -5.6 215 52 27 7.2 4.0 | -20.5 -4.9 215 56 29 7.0 3.9
22000 -18.8 -1.8 215 52 27 7.3 4.0 | -18.4 -1.1 215 55 28 7.1 3.9
21000 -16.6 2.1 215 51 26 7.5 4.1 | -16.3 2.7 210 53 27 7.3 4.0
20000 -14.3 6.3 215 49 25 7.6 4.2 | -14.1 6.6 210 50 26 7.3 4.0
19500 -13.2 8.2 210 49 25 7.6 4.1 | -13.1 8.4 210 49 25 7.3 4.0
19000 -12.1 10.2 210 48 25 7.3 4.0 | -12.0 10.4 210 48 25 7.1 3.9
18500 -11.1 12.0 210 47 24 6.9 3.8 | -11.0 12.2 210 47 24 7.0 3.8
18000 -10.1 13.8 210 47 24 6.9 3.8 | -10.0 14.0 210 45 23 7.1 3.9
17500 -9.2 15.4 210 46 24 6.7 3.7 | -9.0 15.8 205 44 23 6.4 3.5
17000 -8.2 17.2 210 45 23 6.7 3.7 | -8.1 17.4 205 43 22 6.5 3.6
16500 -7.2 19.0 210 44 23 6.5 3.6 | -7.2 19.0 205 42 22 6.4 3.5
16000 -6.3 20.7 210 43 22 6.2 3.4 | -6.3 20.7 205 42 22 6.2 3.4
15500 -5.4 22.3 205 42 22 6.2 3.4 | -5.4 22.3 200 41 21 6.3 3.4
15000 -4.5 23.9 205 41 21 6.2 3.4 | -4.5 23.9 200 41 21 6.4 3.5
14500 -3.7 25.3 205 39 20 6.2 3.4 | -3.6 25.5 200 40 21 6.4 3.5
14000 -2.8 27.0 205 38 20 6.0 3.3 | -2.7 27.1 200 39 20 6.6 3.6
13500 -1.9 28.6 205 37 19 6.0 3.3 | -1.7 28.9 200 39 20 6.7 3.7
13000 -1.1 30.0 200 35 18 6.3 3.5 | -0.8 30.6 195 39 20 6.5 3.5
12500 -0.2 31.6 200 34 18 6.3 3.5 | 0.1 32.2 195 38 20 6.5 3.5
12000 0.7 33.3 200 33 17 6.4 3.5 | 1.0 33.8 195 38 19 6.4 3.5
11500 1.6 34.9 200 31 16 6.4 3.5 | 1.9 35.4 195 37 19 6.4 3.5
11000 2.5 36.5 200 29 15 6.4 3.5 | 2.8 37.0 195 36 19 6.0 3.3
10500 3.4 38.1 200 28 14 6.1 3.4 | 3.7 38.7 195 35 18 5.6 3.1
10250 3.9 39.0 200 27 14 7.5 4.1 | 4.1 39.4 195 34 17 7.2 3.9
10000 4.5 40.1 200 26 13 7.7 4.2 | 4.6 40.3 195 33 17 7.7 4.2
9750 4.9 40.8 200 25 13 6.5 3.6 | 5.1 41.2 195 32 16 6.6 3.6
9500 5.4 41.7 200 24 12 6.9 3.8 | 5.6 42.1 190 30 16 6.6 3.6
9250 5.9 42.6 200 23 12 6.9 3.8 | 6.1 43.0 190 29 15 7.7 4.2
9000 6.4 43.5 200 23 12 6.8 3.7 | 6.7 44.1 190 28 14 8.2 4.5
8750 6.9 44.4 195 22 11 6.6 3.6 | 7.2 45.0 190 26 14 7.4 4.0
8500 7.4 45.3 195 21 11 6.8 3.7 | 8.3 46.9 185 24 12 7.5 4.1
8250 7.8 46.0 195 19 10 6.2 3.4 | 8.8 47.8 185 23 12 7.6 4.2
8000 8.7 47.7 190 17 9 6.3 3.5 | 9.4 48.9 185 21 11 8.1 4.4
7750 9.1 48.4 190 16 8 6.5 3.5 | 10.0 50.0 180 19 10 8.2 4.5
7500 9.5 49.1 185 15 7 4.4 2.4 | 10.6 51.1 180 18 9 7.8 4.3
7250 9.8 49.6 180 14 7 2.7 1.5 | 11.1 52.0 175 17 9 7.5 4.1
7000 10.0 50.0 175 14 7 6.5 3.6 | 11.7 53.1 175 17 9 8.8 4.8
6750 10.6 51.1 170 12 6 6.8 3.7 | 12.4 54.3 170 15 8 9.5 5.2
6500 10.9 51.6 160 11 6 3.5 1.9 | 13.0 55.4 170 14 7 9.1 5.0
6250 11.2 52.2 150 11 6 2.9 1.6 | 13.7 56.7 165 13 7 9.2 5.1
6000 11.4 52.5 145 11 5 5.2 2.9 | 14.4 57.9 165 12 6 8.4 4.6
5750 11.9 53.4 140 7 4 9.9 5.4 | 15.0 59.0 165 10 5 10.2 5.6
5500 12.4 54.3 125 7 3 -2.2 -1.2 | 16.2 61.2 155 9 5 30.2 16.6
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
10/14/2025 at 1500 MDT | 10/14/2025 at 1800 MDT
|
CAPE... +356.4 LI... -1.6 | CAPE... +390.2 LI... -1.4
CINH... -3.3 K Index... +23.4 | CINH... -15.1 K Index... +14.2
|
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 -63.7 -82.7 215 70 36 1.5 0.8 | -63.8 -82.8 215 69 36 1.7 0.9
45000 -60.2 -76.4 220 99 51 5.6 3.1 | -60.2 -76.4 220 98 50 5.3 2.9
40000 -51.8 -61.2 215 113 58 5.5 3.0 | -52.3 -62.1 215 113 58 5.2 2.8
38000 -48.3 -54.9 215 113 58 5.3 2.9 | -48.9 -56.0 215 109 56 5.0 2.7
36000 -45.1 -49.2 215 112 58 5.3 2.9 | -46.0 -50.8 215 105 54 5.0 2.7
34000 -42.0 -43.6 215 102 52 5.2 2.8 | -42.7 -44.9 215 95 49 5.7 3.1
32000 -38.9 -38.0 220 87 45 5.2 2.8 | -39.3 -38.7 215 81 42 5.6 3.1
30000 -35.0 -31.0 220 76 39 7.4 4.0 | -35.1 -31.2 215 73 38 8.0 4.4
29000 -32.8 -27.0 225 72 37 7.4 4.0 | -32.7 -26.9 215 71 36 8.0 4.4
28000 -30.6 -23.1 225 68 35 7.4 4.0 | -30.3 -22.5 215 69 35 8.0 4.4
27000 -28.5 -19.3 225 66 34 6.9 3.8 | -28.0 -18.4 215 67 34 7.3 4.0
26000 -26.4 -15.5 220 64 33 6.9 3.8 | -25.8 -14.4 215 65 33 7.3 4.0
25000 -24.3 -11.7 220 63 32 6.9 3.8 | -23.7 -10.7 215 63 32 7.3 4.0
24000 -21.8 -7.2 215 61 31 6.8 3.7 | -21.1 -6.0 215 61 31 6.5 3.6
23000 -19.7 -3.5 215 59 30 6.8 3.7 | -19.1 -2.4 215 59 30 6.5 3.6
22000 -17.7 0.1 215 56 29 6.8 3.7 | -17.2 1.0 210 57 29 6.5 3.6
21000 -15.7 3.7 210 54 28 6.8 3.7 | -15.2 4.6 210 55 28 6.6 3.6
20000 -13.7 7.3 210 52 27 6.8 3.8 | -13.3 8.1 210 53 27 6.6 3.6
19500 -12.6 9.3 210 52 27 6.9 3.8 | -12.3 9.9 210 52 27 6.6 3.6
19000 -11.6 11.1 210 51 26 7.1 3.9 | -11.3 11.7 210 51 26 6.5 3.6
18500 -10.6 12.9 210 49 25 7.3 4.0 | -10.4 13.3 210 50 26 6.4 3.5
18000 -9.5 14.9 210 48 25 7.4 4.1 | -9.4 15.1 210 49 25 6.3 3.5
17500 -8.5 16.7 210 46 24 6.3 3.4 | -8.4 16.9 205 48 25 7.3 4.0
17000 -7.6 18.3 205 45 23 6.4 3.5 | -7.3 18.9 205 47 24 7.2 4.0
16500 -6.6 20.1 205 43 22 6.0 3.3 | -6.3 20.7 205 45 23 6.8 3.8
16000 -5.9 21.4 205 42 21 5.8 3.2 | -5.3 22.5 205 44 23 6.6 3.6
15500 -5.1 22.8 200 40 21 5.9 3.2 | -4.3 24.3 200 44 22 6.7 3.7
15000 -4.3 24.3 200 39 20 5.8 3.2 | -3.4 25.9 200 43 22 6.8 3.7
14500 -3.5 25.7 195 38 20 5.8 3.2 | -2.4 27.7 195 42 22 6.9 3.8
14000 -2.6 27.3 195 37 19 7.0 3.8 | -1.5 29.3 195 41 21 6.2 3.4
13500 -1.6 29.1 195 36 19 6.9 3.8 | -0.6 30.9 195 40 21 6.4 3.5
13000 -0.6 30.9 190 36 18 7.0 3.8 | 0.2 32.4 190 39 20 6.8 3.8
12500 0.4 32.7 190 35 18 7.0 3.8 | 1.2 34.2 190 38 20 6.9 3.8
12000 1.4 34.5 190 34 18 7.1 3.9 | 2.2 36.0 185 37 19 7.7 4.2
11500 2.4 36.3 190 33 17 7.2 3.9 | 3.3 37.9 185 35 18 7.8 4.3
11000 3.5 38.3 190 31 16 7.3 4.0 | 4.4 39.9 185 33 17 7.5 4.1
10500 4.5 40.1 190 29 15 6.8 3.7 | 5.4 41.7 185 31 16 7.0 3.8
10250 5.0 41.0 190 28 14 9.4 5.1 | 6.0 42.8 185 30 15 8.9 4.9
10000 5.8 42.4 190 28 15 10.1 5.6 | 6.7 44.1 190 29 15 9.4 5.2
9750 6.4 43.5 190 28 14 8.3 4.6 | 7.3 45.1 190 28 14 7.9 4.4
9500 7.1 44.8 190 27 14 8.4 4.6 | 7.9 46.2 190 27 14 8.1 4.4
9250 7.7 45.9 190 26 14 10.0 5.5 | 8.5 47.3 190 26 13 9.0 4.9
9000 8.5 47.3 190 25 13 10.1 5.5 | 9.1 48.4 190 25 13 9.2 5.0
8750 9.1 48.4 190 25 13 8.4 4.6 | 10.4 50.7 190 23 12 8.6 4.7
8500 9.8 49.6 190 24 12 8.8 4.8 | 11.0 51.8 195 22 11 8.4 4.6
8250 11.1 52.0 190 23 12 9.4 5.2 | 11.6 52.9 195 22 11 8.5 4.7
8000 11.8 53.2 190 22 11 9.4 5.2 | 12.3 54.1 195 20 11 9.0 4.9
7750 12.5 54.5 190 21 11 9.4 5.2 | 12.9 55.2 195 19 10 9.1 5.0
7500 13.2 55.8 190 20 10 9.3 5.1 | 13.6 56.5 195 17 9 8.6 4.7
7250 13.9 57.0 190 20 10 9.3 5.1 | 14.2 57.6 195 17 9 8.3 4.6
7000 14.6 58.3 190 19 10 9.4 5.2 | 14.8 58.6 200 16 8 8.7 4.8
6750 15.2 59.4 195 18 9 9.9 5.4 | 15.5 59.9 200 14 7 8.9 4.9
6500 16.0 60.8 195 17 9 10.3 5.6 | 16.1 61.0 200 12 6 8.8 4.8
6250 16.8 62.2 195 16 8 10.8 5.9 | 16.7 62.1 205 11 5 9.1 5.0
6000 17.5 63.5 190 15 8 8.3 4.5 | 17.3 63.1 205 9 5 7.3 4.0
5750 18.0 64.4 195 13 7 7.4 4.1 | 17.6 63.7 205 7 4 1.3 0.7
5500 19.2 66.6 195 11 6 37.2 20.4 | 17.4 63.3 215 4 2 -4.4 -2.4
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
________________________________________________________________________________
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