Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
462
UXUS97 KGJT 011306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Friday, August 1, 2025
This forecast is for Friday, August 1, 2025:
If the trigger temperature of 82.0 F/27.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1725 ft/min (8.8 m/s)
Maximum height of thermals.................. 21383 ft MSL (15774 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 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................. 17873 ft MSL (12265 ft AGL)
Thermal soaring outlook for Saturday 08/02..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:15:14 / 20:25:41 MDT
Total possible sunshine........... 14 hr 10 min 27 sec (850 min 27 sec)
Altitude of sun at 13:20:27 MDT... 68.22 degrees
Upper air data from rawinsonde observation taken on 08/01/2025 at 0600 MDT
Freezing level.................. 15641 ft MSL (10032 ft AGL)
Convective condensation level... 16521 ft MSL (10912 ft AGL)
Lifted condensation level....... 18085 ft MSL (12476 ft AGL)
Lifted index.................... -4.4
K index......................... +25.7
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 -61.2 -78.2 260 29 15 3.1 1.7 M M M M M
45000 -56.2 -69.2 260 50 26 3.8 2.1 M M M M M
40000 -50.4 -58.7 270 67 35 4.1 2.2 M M M M M
38000 -47.9 -54.2 270 69 35 4.1 2.2 M M M M M
36000 -45.2 -49.4 270 71 37 5.1 2.8 M M M M M
34000 -40.7 -41.3 270 67 34 7.7 4.2 M M M M M
32000 -36.0 -32.8 270 63 32 7.9 4.3 M M M M M
30000 -31.6 -24.9 265 57 30 7.4 4.0 43.2 109.8 7.1 M M
29000 -29.4 -20.9 265 55 28 7.4 4.0 42.4 108.3 6.5 M M
28000 -27.2 -17.0 265 52 27 6.5 3.6 41.5 106.7 5.9 M M
27000 -25.3 -13.5 260 49 25 6.4 3.5 40.1 104.2 4.9 M M
26000 -23.4 -10.1 260 46 24 6.5 3.5 38.9 102.0 4.0 M M
25000 -21.4 -6.5 260 43 22 6.7 3.7 37.8 100.0 3.1 M M
24000 -19.3 -2.7 260 39 20 7.3 4.0 36.8 98.2 2.3 M M
23000 -17.1 1.2 260 36 18 7.3 4.0 35.9 96.5 1.5 M M
22000 -14.9 5.2 255 32 16 6.8 3.7 35.1 95.1 0.9 M M
21000 -12.7 9.1 255 27 14 6.4 3.5 33.5 92.2 -0.6 1482 7.5
20000 -10.9 12.4 250 24 12 6.6 3.6 32.3 90.2 -1.7 1398 7.1
19500 -9.9 14.2 250 22 11 7.7 4.2 31.9 89.4 -2.2 1355 6.9
19000 -8.7 16.3 245 20 10 8.3 4.5 31.6 88.9 -2.5 1305 6.6
18500 -7.5 18.5 245 19 10 8.3 4.6 31.3 88.4 -2.8 1254 6.4
18000 -6.3 20.7 245 18 9 9.0 4.9 31.2 88.1 -3.0 1201 6.1
17500 -4.9 23.2 245 17 9 9.0 4.9 31.0 87.8 -3.1 1147 5.8
17000 -3.6 25.5 250 17 9 9.1 5.0 30.9 87.6 -3.3 1092 5.5
16500 -2.3 27.9 250 16 8 9.2 5.0 30.8 87.4 -3.4 1037 5.3
16000 -0.9 30.4 250 16 8 9.3 5.1 30.7 87.3 -3.5 981 5.0
15500 0.5 32.9 250 16 8 9.6 5.3 30.7 87.2 -3.6 924 4.7
15000 2.0 35.6 250 16 8 9.6 5.3 30.6 87.2 -3.6 866 4.4
14500 3.3 37.9 255 16 8 9.0 5.0 30.6 87.0 -3.7 810 4.1
14000 4.7 40.5 255 15 8 9.1 5.0 30.5 86.8 -3.8 754 3.8
13500 6.0 42.8 255 15 8 9.0 4.9 30.4 86.6 -4.0 699 3.6
13000 7.4 45.3 250 15 8 9.0 4.9 30.2 86.4 -4.1 644 3.3
12500 8.7 47.7 250 15 8 8.8 4.8 30.1 86.2 -4.3 590 3.0
12000 10.0 50.0 250 15 8 8.7 4.8 29.9 85.9 -4.5 537 2.7
11500 11.2 52.2 250 15 8 8.3 4.6 29.8 85.6 -4.7 484 2.5
11000 12.4 54.3 245 14 7 8.0 4.4 29.5 85.1 -5.0 434 2.2
10500 13.6 56.5 245 14 7 8.6 4.7 29.3 84.7 -5.3 383 1.9
10250 14.2 57.6 245 14 7 8.1 4.4 29.2 84.5 -5.4 357 1.8
10000 14.8 58.6 240 13 7 8.2 4.5 29.0 84.3 -5.6 332 1.7
9750 15.4 59.7 240 13 7 8.3 4.5 28.9 84.1 -5.7 307 1.6
9500 16.0 60.8 240 13 7 6.6 3.6 28.8 83.8 -5.9 282 1.4
9250 16.4 61.5 240 12 6 6.4 3.5 28.5 83.3 -6.2 262 1.3
9000 17.0 62.6 235 11 6 7.6 4.2 28.3 82.9 -6.4 238 1.2
8750 17.5 63.5 230 11 6 7.2 4.0 28.1 82.6 -6.6 215 1.1
8500 18.0 64.4 225 10 5 6.3 3.5 27.9 82.2 -6.9 192 1.0
8250 18.4 65.1 225 10 5 5.6 3.1 27.6 81.7 -7.2 172 0.9
8000 18.9 66.0 215 9 5 5.9 3.2 27.3 81.1 -7.5 152 0.8
7750 19.3 66.7 210 9 4 5.3 2.9 27.0 80.6 -7.8 132 0.7
7500 19.6 67.3 200 9 5 4.2 2.3 26.6 79.9 -8.2 115 0.6
7250 19.9 67.8 185 10 5 3.5 1.9 26.1 79.0 -8.7 99 0.5
7000 20.2 68.4 180 10 5 5.2 2.8 25.7 78.3 -9.2 83 0.4
6750 20.5 68.9 175 9 5 1.0 0.6 25.3 77.5 -9.6 67 0.3
6500 20.3 68.5 165 9 5 -4.2 -2.3 24.3 75.8 -10.6 65 0.3
6250 20.0 68.0 160 8 4 -2.6 -1.4 23.3 74.0 -11.6 66 0.3
6000 19.8 67.6 150 8 4 -2.2 -1.2 22.5 72.4 -12.5 63 0.3
5750 19.3 66.7 135 6 3 -16.8 -9.2 21.2 70.1 -13.9 73 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 * * * * * *
08/01/2025 at 0900 MDT | 08/01/2025 at 1200 MDT
|
CAPE... +330.0 LI... -2.5 | CAPE... +558.3 LI... -2.8
CINH... -137.4 K Index... +23.6 | CINH... -14.4 K Index... +27.2
|
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 -60.1 -76.2 260 26 13 3.3 1.8 | -60.6 -77.1 265 28 14 2.8 1.5
45000 -54.7 -66.5 260 46 24 4.3 2.4 | -55.8 -68.4 265 50 26 4.1 2.2
40000 -48.5 -55.3 265 56 29 3.0 1.6 | -49.7 -57.5 265 55 28 3.9 2.2
38000 -46.4 -51.5 265 59 30 3.0 1.7 | -47.1 -52.8 270 58 30 3.9 2.2
36000 -44.6 -48.3 265 61 31 2.8 1.5 | -44.7 -48.5 275 60 31 3.9 2.1
34000 -41.9 -43.4 265 53 27 4.8 2.6 | -41.6 -42.9 270 54 28 5.4 3.0
32000 -39.0 -38.2 265 42 22 4.6 2.5 | -38.3 -36.9 270 46 24 5.3 2.9
30000 -34.8 -30.6 265 38 19 7.6 4.1 | -34.2 -29.6 265 39 20 7.1 3.9
29000 -32.5 -26.5 265 36 18 7.6 4.1 | -32.1 -25.8 265 36 19 7.1 3.9
28000 -30.3 -22.5 265 34 17 7.6 4.2 | -30.0 -22.0 265 33 17 7.8 4.3
27000 -28.0 -18.4 260 32 17 7.6 4.2 | -27.5 -17.5 265 32 17 8.1 4.4
26000 -25.7 -14.3 260 31 16 7.6 4.2 | -25.1 -13.2 265 31 16 8.1 4.4
25000 -23.5 -10.3 255 29 15 7.6 4.2 | -22.7 -8.9 265 30 15 7.9 4.4
24000 -21.5 -6.7 255 28 14 6.6 3.6 | -20.1 -4.2 260 28 14 6.8 3.7
23000 -19.1 -2.4 245 27 14 6.6 3.6 | -18.1 -0.6 250 26 14 6.9 3.8
22000 -17.1 1.2 245 26 13 8.1 4.5 | -16.1 3.0 240 25 13 7.4 4.0
21000 -14.7 5.5 240 26 13 8.3 4.6 | -14.0 6.8 240 25 13 7.5 4.1
20000 -12.2 10.0 235 26 13 8.4 4.6 | -11.8 10.8 235 24 12 7.6 4.2
19500 -11.0 12.2 235 26 13 8.4 4.6 | -10.7 12.7 230 24 12 8.0 4.4
19000 -9.8 14.4 230 25 13 8.4 4.6 | -9.5 14.9 230 24 12 8.3 4.6
18500 -8.6 16.5 230 24 12 8.4 4.6 | -8.3 17.1 230 23 12 8.4 4.6
18000 -7.3 18.9 230 22 12 8.5 4.7 | -7.2 19.0 230 23 12 8.0 4.4
17500 -6.1 21.0 230 21 11 8.5 4.7 | -6.0 21.2 230 23 12 8.1 4.4
17000 -4.8 23.4 230 19 10 8.9 4.9 | -4.8 23.4 230 22 11 8.1 4.4
16500 -3.4 25.9 230 18 9 9.1 5.0 | -3.6 25.5 230 22 11 8.1 4.5
16000 -2.0 28.4 230 17 9 9.1 5.0 | -2.4 27.7 230 21 11 8.2 4.5
15500 -0.7 30.7 230 15 8 8.9 4.9 | -1.1 30.0 230 20 10 8.9 4.9
15000 0.6 33.1 230 14 7 8.9 4.9 | 0.2 32.4 225 19 10 8.8 4.9
14500 2.0 35.6 230 13 7 8.9 4.9 | 1.5 34.7 225 18 9 9.3 5.1
14000 3.3 37.9 230 12 6 8.9 4.9 | 2.9 37.2 225 17 9 9.2 5.1
13500 4.6 40.3 235 11 6 8.6 4.7 | 4.3 39.7 225 16 8 9.4 5.1
13000 5.9 42.6 235 10 5 8.5 4.7 | 5.7 42.3 225 16 8 9.4 5.2
12500 7.1 44.8 240 9 5 8.4 4.6 | 7.1 44.8 225 15 8 9.4 5.2
12000 8.3 46.9 240 9 5 8.3 4.6 | 8.6 47.5 220 14 7 9.4 5.1
11500 9.5 49.1 245 9 5 8.3 4.6 | 10.0 50.0 220 13 7 9.4 5.2
11000 10.7 51.3 245 9 4 8.3 4.5 | 11.3 52.3 220 13 7 9.4 5.2
10500 11.9 53.4 245 8 4 7.0 3.8 | 12.7 54.9 220 12 6 9.2 5.0
10250 12.3 54.1 245 8 4 7.0 3.9 | 13.4 56.1 220 11 6 9.2 5.0
10000 12.9 55.2 245 8 4 9.0 4.9 | 14.1 57.4 220 11 6 9.5 5.2
9750 13.6 56.5 240 8 4 8.6 4.7 | 14.8 58.6 220 11 6 9.3 5.1
9500 14.2 57.6 240 8 4 8.7 4.8 | 15.5 59.9 215 11 5 9.8 5.4
9250 14.8 58.6 235 8 4 8.5 4.7 | 16.2 61.2 215 10 5 9.8 5.4
9000 15.4 59.7 235 7 4 7.4 4.1 | 16.9 62.4 215 9 5 8.7 4.8
8750 15.8 60.4 225 8 4 6.6 3.6 | 18.1 64.6 210 9 5 8.8 4.8
8500 16.9 62.4 215 8 4 7.6 4.2 | 18.7 65.7 210 8 4 9.1 5.0
8250 17.4 63.3 210 8 4 6.9 3.8 | 19.4 66.9 210 8 4 9.0 4.9
8000 17.8 64.0 200 9 4 5.6 3.1 | 20.0 68.0 210 8 4 9.1 5.0
7750 18.2 64.8 195 9 5 5.3 2.9 | 20.7 69.3 210 8 4 9.2 5.1
7500 18.6 65.5 185 9 5 4.9 2.7 | 21.4 70.5 205 7 4 9.2 5.0
7250 19.0 66.2 175 10 5 6.1 3.3 | 22.0 71.6 205 7 3 9.6 5.3
7000 19.4 66.9 175 9 5 6.9 3.8 | 22.8 73.0 205 7 3 10.1 5.5
6750 19.9 67.8 170 8 4 5.9 3.2 | 23.5 74.3 205 7 3 10.0 5.5
6500 20.3 68.5 165 8 4 5.6 3.0 | 24.2 75.6 205 6 3 9.7 5.3
6250 20.7 69.3 160 7 4 5.9 3.2 | 24.9 76.8 200 6 3 10.6 5.8
6000 21.3 70.3 155 9 5 11.5 6.3 | 25.9 78.6 195 5 3 17.2 9.4
5750 22.5 72.5 150 8 4 19.8 10.9 | 27.5 81.5 195 5 2 25.3 13.9
5500 23.7 74.7 150 7 3 5.4 3.0 | 29.1 84.4 195 4 2 11.8 6.5
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
08/01/2025 at 1500 MDT | 08/01/2025 at 1800 MDT
|
CAPE... +372.8 LI... -1.8 | CAPE... +74.4 LI... +0.4
CINH... -11.2 K Index... +29.1 | CINH... -40.5 K Index... +20.2
|
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 -61.1 -78.0 265 29 15 2.8 1.5 | -61.0 -77.8 270 29 15 2.7 1.5
45000 -56.3 -69.3 265 51 26 4.1 2.3 | -56.1 -69.0 270 52 27 4.3 2.4
40000 -49.8 -57.6 270 60 31 4.4 2.4 | -49.4 -56.9 270 62 32 4.2 2.3
38000 -47.1 -52.8 275 62 32 4.4 2.4 | -46.9 -52.4 270 65 33 4.2 2.3
36000 -44.5 -48.1 275 64 33 4.6 2.5 | -44.3 -47.7 275 68 35 4.6 2.5
34000 -41.0 -41.8 275 57 29 6.1 3.3 | -40.6 -41.1 275 63 32 6.4 3.5
32000 -37.3 -35.1 275 50 26 6.0 3.3 | -36.8 -34.2 275 58 30 6.3 3.5
30000 -33.5 -28.3 270 43 22 6.4 3.5 | -33.0 -27.4 275 48 25 6.3 3.5
29000 -31.6 -24.9 270 40 20 6.4 3.5 | -31.1 -24.0 270 44 22 6.3 3.5
28000 -29.6 -21.3 265 37 19 8.0 4.4 | -29.1 -20.4 270 39 20 7.8 4.3
27000 -27.1 -16.8 265 34 18 8.3 4.6 | -26.7 -16.1 270 35 18 8.1 4.5
26000 -24.6 -12.3 265 32 16 8.3 4.6 | -24.3 -11.7 265 30 16 8.1 4.5
25000 -22.1 -7.8 265 29 15 8.2 4.5 | -21.2 -6.2 265 25 13 7.8 4.3
24000 -19.2 -2.6 260 27 14 7.7 4.2 | -18.9 -2.0 260 23 12 7.7 4.3
23000 -17.0 1.4 255 24 13 7.7 4.2 | -16.6 2.1 255 21 11 7.8 4.3
22000 -14.8 5.4 250 23 12 7.0 3.8 | -14.3 6.3 250 20 10 7.4 4.1
21000 -12.7 9.1 245 22 12 7.1 3.9 | -12.1 10.2 245 20 10 7.5 4.1
20000 -10.7 12.7 240 22 11 7.2 4.0 | -9.9 14.2 245 21 11 7.6 4.2
19500 -9.7 14.5 235 22 11 7.7 4.2 | -8.8 16.2 245 21 11 7.7 4.2
19000 -8.5 16.7 235 22 11 7.9 4.3 | -7.7 18.1 240 21 11 7.7 4.2
18500 -7.4 18.7 235 22 11 7.9 4.4 | -6.6 20.1 240 21 11 7.7 4.2
18000 -6.2 20.8 235 21 11 8.8 4.8 | -5.4 22.3 240 21 11 9.0 5.0
17500 -4.9 23.2 235 21 11 8.7 4.8 | -4.1 24.6 240 21 11 9.0 4.9
17000 -3.6 25.5 235 20 11 8.6 4.7 | -2.8 27.0 240 20 10 9.2 5.1
16500 -2.4 27.7 235 20 10 8.6 4.7 | -1.4 29.5 240 20 10 9.4 5.2
16000 -1.1 30.0 235 19 10 8.7 4.8 | -0.0 32.0 240 20 10 9.5 5.2
15500 0.2 32.4 235 19 10 8.8 4.8 | 1.4 34.5 240 20 10 9.6 5.3
15000 1.4 34.5 235 19 10 8.7 4.8 | 2.8 37.0 240 19 10 9.6 5.3
14500 2.8 37.0 240 18 9 9.0 4.9 | 4.2 39.6 245 19 10 9.4 5.2
14000 4.1 39.4 240 18 9 8.9 4.9 | 5.6 42.1 245 19 10 9.4 5.2
13500 5.4 41.7 240 17 9 9.5 5.2 | 7.0 44.6 245 19 10 9.3 5.1
13000 6.9 44.4 240 17 9 9.5 5.2 | 8.4 47.1 245 19 10 9.3 5.1
12500 8.3 46.9 240 17 9 9.5 5.2 | 9.8 49.6 245 18 9 9.4 5.1
12000 9.7 49.5 240 16 8 9.5 5.2 | 11.2 52.2 250 18 9 9.4 5.1
11500 11.1 52.0 245 16 8 9.5 5.2 | 12.6 54.7 250 18 9 9.4 5.1
11000 12.5 54.5 245 15 8 9.5 5.2 | 14.0 57.2 250 18 9 9.3 5.1
10500 14.0 57.2 245 15 8 8.9 4.9 | 15.4 59.7 250 17 9 9.1 5.0
10250 14.6 58.3 245 14 7 9.3 5.1 | 16.0 60.8 255 17 9 9.0 5.0
10000 15.4 59.7 245 14 7 10.2 5.6 | 16.7 62.1 255 17 9 9.4 5.2
9750 16.1 61.0 245 14 7 9.8 5.4 | 17.4 63.3 255 16 8 9.2 5.1
9500 16.9 62.4 245 14 7 10.8 5.9 | 18.1 64.6 255 16 8 9.7 5.3
9250 17.7 63.9 250 14 7 10.9 6.0 | 18.9 66.0 255 16 8 9.6 5.3
9000 18.5 65.3 250 14 7 9.2 5.0 | 20.2 68.4 255 15 8 8.6 4.7
8750 19.1 66.4 250 14 7 8.7 4.8 | 20.8 69.4 255 14 7 8.7 4.8
8500 20.5 68.9 250 13 7 9.8 5.4 | 21.5 70.7 260 14 7 8.2 4.5
8250 21.2 70.2 250 13 7 9.7 5.3 | 22.1 71.8 260 15 8 9.8 5.4
8000 22.0 71.6 250 13 7 9.7 5.3 | 22.9 73.2 260 14 7 11.4 6.2
7750 22.7 72.9 250 13 7 9.6 5.3 | 23.7 74.7 260 14 7 9.4 5.2
7500 23.4 74.1 250 13 7 9.6 5.3 | 24.3 75.7 260 14 7 8.1 4.5
7250 24.1 75.4 250 12 6 9.8 5.4 | 25.0 77.0 260 14 7 9.5 5.2
7000 24.9 76.8 250 12 6 10.1 5.5 | 25.8 78.4 260 14 7 11.4 6.3
6750 25.6 78.1 250 12 6 10.1 5.6 | 26.6 79.9 260 13 7 10.9 6.0
6500 26.4 79.5 250 11 6 9.8 5.4 | 27.4 81.3 260 13 7 10.7 5.9
6250 27.1 80.8 250 11 6 11.0 6.0 | 28.2 82.8 260 13 7 8.8 4.9
6000 28.1 82.6 255 11 6 17.8 9.8 | 28.8 83.8 260 12 6 11.9 6.5
5750 29.8 85.6 255 10 5 25.3 13.9 | 30.2 86.4 265 11 6 23.6 13.0
5500 31.4 88.5 255 9 5 13.1 7.2 | 31.6 88.9 265 11 6 3.8 2.1
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
________________________________________________________________________________
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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