Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
465
UXUS97 KGJT 031306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Friday, October 3, 2025
This forecast is for Friday, October 3, 2025:
If the trigger temperature of 67.9 F/19.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1598 ft/min (8.1 m/s)
Maximum height of thermals.................. 21193 ft MSL (15584 ft AGL)
Forecast maximum temperature................... 86.0 F/30.5 C
Time of trigger temperature.................... 0930 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................. 18239 ft MSL (12630 ft AGL)
Thermal soaring outlook for Saturday 10/04..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:12:39 / 18:53:21 MDT
Total possible sunshine........... 11 hr 40 min 42 sec (700 min 42 sec)
Altitude of sun at 13:03:00 MDT... 46.59 degrees
Upper air data from rawinsonde observation taken on 10/03/2025 at 0600 MDT
Freezing level.................. 12707 ft MSL (7098 ft AGL)
Convective condensation level... 11792 ft MSL (6183 ft AGL)
Lifted condensation level....... 15597 ft MSL (9988 ft AGL)
Lifted index.................... -7.3
K index......................... +27.9
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 -60.4 -76.7 225 46 24 3.0 1.6 M M M M M
45000 -56.1 -69.0 220 69 36 1.3 0.7 M M M M M
40000 -54.2 -65.6 220 84 43 1.0 0.6 M M M M M
38000 -52.0 -61.6 220 87 45 4.1 2.3 M M M M M
36000 -49.5 -57.1 215 90 46 4.1 2.3 M M M M M
34000 -46.2 -51.2 215 90 46 7.4 4.1 M M M M M
32000 -41.2 -42.2 210 87 45 7.4 4.0 M M M M M
30000 -36.7 -34.1 210 83 43 7.7 4.2 38.1 100.6 6.2 M M
29000 -34.4 -29.9 210 80 41 7.7 4.2 37.3 99.1 5.6 M M
28000 -32.1 -25.8 205 78 40 7.7 4.2 36.6 97.9 5.1 M M
27000 -29.8 -21.6 205 75 39 7.5 4.1 35.8 96.4 4.5 M M
26000 -27.6 -17.7 200 71 37 7.5 4.1 34.9 94.7 3.8 M M
25000 -25.4 -13.7 200 67 35 7.5 4.1 34.0 93.3 3.2 M M
24000 -23.2 -9.8 195 64 33 6.9 3.8 33.2 91.8 2.5 M M
23000 -21.2 -6.2 195 62 32 6.9 3.8 32.1 89.8 1.6 M M
22000 -19.2 -2.6 195 60 31 7.0 3.8 31.1 88.1 0.8 M M
21000 -17.1 1.2 195 58 30 6.6 3.6 30.1 86.3 -0.1 1389 7.1
20000 -15.2 4.6 200 57 30 6.6 3.6 29.0 84.2 -1.2 1301 6.6
19500 -14.3 6.3 200 57 29 6.7 3.7 28.5 83.2 -1.6 1258 6.4
19000 -12.8 9.0 200 57 29 6.7 3.7 27.7 81.9 -2.3 1192 6.1
18500 -11.8 10.8 200 56 29 6.7 3.7 27.2 80.9 -2.8 1148 5.8
18000 -10.8 12.6 200 55 28 6.7 3.7 26.7 80.0 -3.3 1104 5.6
17500 -9.9 14.2 205 54 28 6.7 3.7 26.1 79.1 -3.8 1060 5.4
17000 -8.9 16.0 205 53 28 6.7 3.7 25.6 78.1 -4.4 1016 5.2
16500 -7.9 17.8 205 53 27 6.8 3.7 25.1 77.2 -4.9 972 4.9
16000 -6.9 19.6 205 52 27 6.9 3.8 24.6 76.3 -5.4 927 4.7
15500 -5.9 21.4 205 51 26 6.9 3.8 24.1 75.5 -5.8 882 4.5
15000 -4.9 23.2 205 49 25 7.2 4.0 23.7 74.7 -6.3 837 4.3
14500 -3.8 25.2 205 48 25 7.2 3.9 23.3 73.9 -6.8 791 4.0
14000 -2.8 27.0 205 47 24 7.4 4.1 22.9 73.2 -7.2 744 3.8
13500 -1.7 28.9 210 46 24 7.5 4.1 22.5 72.5 -7.6 697 3.5
13000 -0.6 30.9 210 45 23 7.8 4.3 22.1 71.9 -8.0 650 3.3
12500 0.5 32.9 210 44 23 7.9 4.4 21.8 71.3 -8.4 601 3.1
12000 1.6 34.9 210 43 22 8.6 4.7 21.6 70.9 -8.7 552 2.8
11500 2.9 37.2 210 41 21 9.0 4.9 21.5 70.6 -9.0 498 2.5
11000 4.2 39.6 205 40 21 8.7 4.8 21.3 70.4 -9.2 445 2.3
10500 5.5 41.9 205 38 20 9.1 5.0 21.1 70.1 -9.4 393 2.0
10250 6.2 43.2 205 38 19 10.0 5.5 21.1 70.1 -9.5 365 1.9
10000 6.9 44.4 205 37 19 9.5 5.2 21.1 70.1 -9.5 336 1.7
9750 7.6 45.7 205 36 19 9.2 5.1 21.1 70.0 -9.6 308 1.6
9500 8.2 46.8 205 36 19 9.3 5.1 21.1 69.9 -9.7 281 1.4
9250 8.9 48.0 205 36 18 9.0 5.0 21.0 69.9 -9.8 253 1.3
9000 9.5 49.1 205 34 18 8.6 4.7 21.0 69.7 -9.9 227 1.2
8750 10.2 50.4 200 33 17 8.3 4.6 20.9 69.5 -10.0 201 1.0
8500 10.8 51.4 200 33 17 8.7 4.8 20.8 69.4 -10.2 175 0.9
8250 11.4 52.5 200 32 16 7.6 4.2 20.7 69.2 -10.3 149 0.8
8000 11.9 53.4 200 30 15 6.6 3.6 20.4 68.8 -10.6 127 0.6
7750 12.4 54.3 195 28 14 6.8 3.7 20.2 68.4 -10.8 105 0.5
7500 12.8 55.0 190 27 14 7.0 3.8 20.0 68.0 -11.1 83 0.4
7250 13.3 55.9 190 25 13 6.1 3.3 19.8 67.6 -11.4 61 0.3
7000 13.7 56.7 185 24 12 5.3 2.9 19.4 67.0 -11.7 42 0.2
6750 14.1 57.4 180 22 11 5.6 3.1 19.1 66.4 -12.1 23 0.1
6500 14.5 58.1 175 20 10 5.4 3.0 18.8 65.8 -12.4 4 0.0
6250 14.8 58.6 170 18 9 0.3 0.2 18.3 65.0 -12.9 M M
6000 14.5 58.1 165 15 8 -5.6 -3.1 17.4 63.2 -14.0 M M
5750 14.1 57.4 160 11 6 -4.6 -2.5 16.2 61.2 -15.2 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 * * * * * *
10/03/2025 at 0900 MDT | 10/03/2025 at 1200 MDT
|
CAPE... 0.0 LI... +2.9 | CAPE... +0.2 LI... +2.2
CINH... -0.1 K Index... +16.8 | CINH... -0.0 K Index... +18.8
|
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 -65.6 -86.1 230 51 26 1.9 1.1 | -65.2 -85.4 225 53 27 2.2 1.2
45000 -61.0 -77.8 230 72 37 5.8 3.2 | -60.6 -77.1 225 78 40 5.3 2.9
40000 -52.3 -62.1 235 83 43 5.2 2.9 | -52.6 -62.7 230 90 46 5.3 2.9
38000 -49.2 -56.6 230 76 39 5.3 2.9 | -49.4 -56.9 230 83 43 5.3 2.9
36000 -46.0 -50.8 230 69 36 5.3 2.9 | -46.3 -51.3 225 76 39 5.3 2.9
34000 -42.0 -43.6 225 61 31 6.2 3.4 | -42.6 -44.7 225 67 34 6.4 3.5
32000 -38.2 -36.8 220 54 28 6.2 3.4 | -38.7 -37.7 220 57 29 6.5 3.6
30000 -33.7 -28.7 220 49 25 8.0 4.4 | -34.2 -29.6 220 52 27 7.9 4.3
29000 -31.3 -24.3 215 46 24 8.0 4.4 | -31.8 -25.2 215 50 26 7.9 4.3
28000 -28.9 -20.0 215 44 23 7.9 4.3 | -29.5 -21.1 215 49 25 8.0 4.4
27000 -26.6 -15.9 215 43 22 7.5 4.1 | -26.7 -16.1 215 47 24 7.3 4.0
26000 -24.4 -11.9 215 42 22 7.5 4.1 | -24.5 -12.1 215 46 24 7.3 4.0
25000 -22.1 -7.8 215 41 21 7.5 4.1 | -22.3 -8.1 215 45 23 7.2 4.0
24000 -19.8 -3.6 215 39 20 8.2 4.5 | -20.0 -4.0 215 44 22 7.9 4.3
23000 -17.3 0.9 215 38 20 8.2 4.5 | -17.7 0.1 215 42 22 7.9 4.3
22000 -14.3 6.3 215 36 19 7.4 4.1 | -15.3 4.5 215 41 21 7.7 4.2
21000 -12.4 9.7 215 35 18 6.3 3.4 | -13.3 8.1 215 40 21 6.6 3.6
20000 -10.6 12.9 215 34 18 6.3 3.4 | -11.3 11.7 215 39 20 6.6 3.6
19500 -9.6 14.7 215 34 17 6.4 3.5 | -10.3 13.5 215 38 20 6.7 3.7
19000 -8.8 16.2 215 34 17 4.6 2.5 | -9.4 15.1 220 38 19 5.6 3.1
18500 -8.1 17.4 215 34 17 4.8 2.6 | -8.6 16.5 220 37 19 5.5 3.0
18000 -7.4 18.7 215 34 17 4.7 2.6 | -7.8 18.0 220 37 19 5.5 3.0
17500 -6.8 19.8 215 34 18 4.6 2.5 | -7.0 19.4 220 36 19 5.3 2.9
17000 -6.2 20.8 215 34 18 4.6 2.5 | -6.3 20.7 220 36 18 5.2 2.9
16500 -5.4 22.3 215 35 18 6.6 3.6 | -5.5 22.1 220 35 18 6.5 3.6
16000 -4.5 23.9 215 35 18 6.3 3.5 | -4.6 23.7 220 34 18 6.6 3.6
15500 -3.5 25.7 215 35 18 8.1 4.4 | -3.6 25.5 215 33 17 7.5 4.1
15000 -2.2 28.0 215 34 18 8.5 4.6 | -2.4 27.7 215 32 17 8.0 4.4
14500 -1.0 30.2 215 34 17 8.6 4.7 | -1.3 29.7 215 32 16 8.3 4.6
14000 0.3 32.5 215 33 17 8.7 4.8 | 0.0 32.0 215 31 16 8.9 4.9
13500 1.6 34.9 215 33 17 8.8 4.8 | 1.4 34.5 215 30 16 8.9 4.9
13000 2.9 37.2 215 32 16 9.1 5.0 | 2.7 36.9 215 30 15 9.1 5.0
12500 4.2 39.6 215 31 16 9.1 5.0 | 4.0 39.2 215 29 15 9.1 5.0
12000 5.6 42.1 215 30 15 9.0 4.9 | 5.4 41.7 210 28 15 9.0 4.9
11500 6.9 44.4 215 29 15 9.0 5.0 | 6.7 44.1 210 28 14 9.0 4.9
11000 8.2 46.8 215 28 14 8.9 4.9 | 8.0 46.4 210 27 14 9.0 4.9
10500 9.5 49.1 210 26 14 8.5 4.6 | 9.4 48.9 210 27 14 8.8 4.8
10250 10.1 50.2 210 25 13 7.9 4.3 | 10.0 50.0 210 26 13 8.2 4.5
10000 10.7 51.3 210 25 13 8.6 4.7 | 10.6 51.1 210 26 13 9.0 5.0
9750 11.4 52.5 210 24 13 8.8 4.9 | 11.3 52.3 205 25 13 9.8 5.4
9500 12.0 53.6 210 24 12 8.9 4.9 | 12.1 53.8 205 25 13 9.6 5.3
9250 12.7 54.9 210 24 12 10.2 5.6 | 13.5 56.3 205 23 12 9.5 5.2
9000 13.5 56.3 210 23 12 8.3 4.6 | 14.2 57.6 200 23 12 8.8 4.9
8750 13.9 57.0 205 22 11 5.9 3.3 | 14.9 58.8 200 22 11 9.0 5.0
8500 14.4 57.9 205 22 11 6.8 3.7 | 15.5 59.9 200 21 11 8.7 4.8
8250 15.5 59.9 200 21 11 7.1 3.9 | 16.2 61.2 200 21 11 9.2 5.0
8000 16.0 60.8 200 20 10 4.9 2.7 | 16.9 62.4 195 20 10 10.2 5.6
7750 16.3 61.3 190 19 10 4.4 2.4 | 17.7 63.9 195 19 10 9.8 5.4
7500 16.6 61.9 185 19 10 4.1 2.2 | 18.4 65.1 195 19 10 8.8 4.8
7250 16.9 62.4 185 19 10 3.9 2.1 | 19.0 66.2 195 19 10 9.0 4.9
7000 17.2 63.0 180 18 9 3.0 1.7 | 19.8 67.6 195 19 10 11.0 6.0
6750 17.4 63.3 170 15 8 1.4 0.8 | 20.6 69.1 195 17 9 11.5 6.3
6500 17.4 63.3 165 15 7 0.8 0.4 | 21.5 70.7 195 17 9 11.0 6.0
6250 17.5 63.5 160 14 7 0.7 0.4 | 22.3 72.1 190 17 9 10.3 5.7
6000 17.6 63.7 155 12 6 1.8 1.0 | 23.1 73.6 190 16 8 11.9 6.5
5750 17.8 64.0 145 8 4 4.6 2.5 | 24.2 75.6 190 14 7 21.5 11.8
5500 18.1 64.6 130 7 4 1.0 0.5 | 26.3 79.3 190 13 7 34.3 18.8
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
10/03/2025 at 1500 MDT | 10/03/2025 at 1800 MDT
|
CAPE... +27.1 LI... -0.3 | CAPE... +60.3 LI... -1.3
CINH... -8.1 K Index... +24.7 | CINH... -22.0 K Index... +27.6
|
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 -64.6 -84.3 230 56 29 2.3 1.3 | -63.9 -83.0 230 53 28 1.9 1.0
45000 -60.4 -76.7 225 82 42 4.5 2.5 | -60.3 -76.5 230 78 40 4.5 2.4
40000 -53.2 -63.8 225 94 48 5.1 2.8 | -53.3 -63.9 230 87 45 4.6 2.5
38000 -50.1 -58.2 225 86 44 5.1 2.8 | -50.5 -58.9 230 82 42 4.6 2.5
36000 -47.0 -52.6 225 79 41 5.1 2.8 | -47.7 -53.9 225 76 39 4.6 2.6
34000 -43.2 -45.8 225 71 37 6.9 3.8 | -44.0 -47.2 225 70 36 6.9 3.8
32000 -39.1 -38.4 220 63 32 6.9 3.8 | -39.8 -39.6 225 63 32 6.9 3.8
30000 -34.6 -30.3 220 57 29 7.9 4.3 | -35.2 -31.4 220 56 29 8.1 4.5
29000 -32.2 -26.0 220 54 28 7.9 4.3 | -32.8 -27.0 220 54 28 8.1 4.5
28000 -29.9 -21.8 220 52 27 7.9 4.4 | -30.4 -22.7 220 51 26 8.2 4.5
27000 -27.6 -17.7 220 50 26 7.4 4.1 | -28.0 -18.4 220 49 25 7.7 4.2
26000 -24.8 -12.6 220 49 25 7.4 4.1 | -25.7 -14.3 215 47 24 7.7 4.2
25000 -22.6 -8.7 220 47 24 7.4 4.1 | -22.8 -9.0 215 45 23 7.8 4.3
24000 -20.4 -4.7 215 46 24 7.3 4.0 | -20.7 -5.3 215 44 23 7.0 3.9
23000 -18.3 -0.9 215 46 24 7.3 4.0 | -18.6 -1.5 215 43 22 7.0 3.9
22000 -16.1 3.0 215 45 23 7.2 4.0 | -16.5 2.3 215 42 22 7.1 3.9
21000 -14.2 6.4 215 43 22 6.2 3.4 | -14.6 5.7 210 41 21 6.6 3.6
20000 -12.4 9.7 215 41 21 6.3 3.5 | -12.7 9.1 210 39 20 6.7 3.7
19500 -11.5 11.3 215 40 21 6.3 3.5 | -11.7 10.9 210 38 20 6.7 3.7
19000 -10.6 12.9 215 39 20 6.7 3.7 | -10.7 12.7 210 37 19 7.2 3.9
18500 -9.6 14.7 215 38 19 6.8 3.7 | -9.7 14.5 210 37 19 7.3 4.0
18000 -8.6 16.5 215 36 18 7.0 3.9 | -8.6 16.5 205 36 19 7.4 4.1
17500 -7.6 18.3 210 34 18 7.6 4.1 | -7.5 18.5 205 36 18 7.9 4.3
17000 -6.5 20.3 210 33 17 7.5 4.1 | -6.4 20.5 205 35 18 7.8 4.3
16500 -5.4 22.3 210 31 16 8.2 4.5 | -5.2 22.6 205 35 18 8.3 4.5
16000 -4.2 24.4 210 30 16 8.2 4.5 | -4.0 24.8 200 35 18 8.4 4.6
15500 -3.0 26.6 210 29 15 8.5 4.7 | -2.8 27.0 200 34 18 8.6 4.7
15000 -1.7 28.9 205 29 15 8.8 4.8 | -1.5 29.3 200 34 17 9.0 4.9
14500 -0.4 31.3 205 29 15 8.9 4.9 | -0.2 31.6 200 33 17 9.0 4.9
14000 1.0 33.8 205 28 15 9.3 5.1 | 1.2 34.2 200 32 17 9.3 5.1
13500 2.4 36.3 205 28 14 9.3 5.1 | 2.5 36.5 200 32 16 9.2 5.1
13000 3.8 38.8 205 28 14 9.4 5.2 | 3.9 39.0 200 31 16 9.7 5.3
12500 5.2 41.4 205 27 14 9.4 5.2 | 5.4 41.7 200 31 16 9.6 5.3
12000 6.6 43.9 205 27 14 9.6 5.3 | 6.8 44.2 200 30 15 9.6 5.3
11500 8.0 46.4 205 27 14 9.6 5.3 | 8.2 46.8 200 29 15 9.7 5.3
11000 9.4 48.9 205 26 13 8.9 4.9 | 9.6 49.3 200 29 15 8.2 4.5
10500 10.7 51.3 205 25 13 9.6 5.2 | 10.8 51.4 200 28 14 8.7 4.8
10250 11.5 52.7 205 25 13 11.3 6.2 | 11.6 52.9 200 27 14 12.4 6.8
10000 12.3 54.1 205 25 13 10.3 5.6 | 12.5 54.5 205 27 14 11.5 6.3
9750 13.1 55.6 205 25 13 9.3 5.1 | 13.2 55.8 205 27 14 9.0 4.9
9500 13.8 56.8 205 25 13 9.3 5.1 | 13.9 57.0 205 26 13 10.0 5.5
9250 14.5 58.1 205 25 13 10.1 5.5 | 14.7 58.5 205 26 13 8.4 4.6
9000 16.0 60.8 205 24 12 9.2 5.1 | 15.2 59.4 205 25 13 8.8 4.8
8750 16.7 62.1 205 24 12 9.6 5.3 | 16.8 62.2 205 24 12 10.4 5.7
8500 17.4 63.3 205 24 12 8.6 4.7 | 17.5 63.5 205 23 12 9.1 5.0
8250 18.0 64.4 205 23 12 9.2 5.0 | 18.2 64.8 205 23 12 8.8 4.8
8000 18.8 65.8 205 23 12 10.7 5.9 | 18.9 66.0 205 22 11 10.1 5.5
7750 19.5 67.1 210 22 11 10.3 5.7 | 19.6 67.3 205 21 11 10.0 5.5
7500 20.3 68.5 210 22 11 8.8 4.8 | 20.3 68.5 205 20 10 8.6 4.7
7250 20.9 69.6 205 22 11 8.5 4.6 | 20.9 69.6 205 20 10 7.9 4.4
7000 21.6 70.9 210 21 11 10.7 5.9 | 21.6 70.9 205 19 10 9.8 5.4
6750 22.4 72.3 210 20 11 11.2 6.1 | 22.4 72.3 205 17 9 10.2 5.6
6500 23.2 73.8 210 20 10 10.5 5.8 | 23.1 73.6 210 16 8 9.6 5.3
6250 24.0 75.2 210 20 10 10.5 5.8 | 23.8 74.8 210 16 8 9.6 5.3
6000 24.8 76.6 210 19 10 9.6 5.3 | 24.5 76.1 210 15 8 7.9 4.3
5750 25.6 78.1 210 17 9 14.6 8.0 | 24.9 76.8 210 12 6 5.0 2.7
5500 27.7 81.9 210 15 8 50.2 27.5 | 25.5 77.9 210 10 5 14.0 7.7
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
________________________________________________________________________________
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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