Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
991
UXUS97 KGJT 051305
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
705 AM MDT Tuesday, August 5, 2025
This forecast is for Tuesday, August 5, 2025:
If the trigger temperature of 84.9 F/29.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1582 ft/min (8.0 m/s)
Maximum height of thermals.................. 21982 ft MSL (16372 ft AGL)
Forecast maximum temperature................... 97.0 F/36.6 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................. 18386 ft MSL (12776 ft AGL)
Thermal soaring outlook for Wednesday 08/06.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:18:50 / 20:21:22 MDT
Total possible sunshine........... 14 hr 2 min 31 sec (842 min 31 sec)
Altitude of sun at 13:20:06 MDT... 67.20 degrees
Upper air data from rawinsonde observation taken on 08/05/2025 at 0600 MDT
Freezing level.................. 16127 ft MSL (10517 ft AGL)
Convective condensation level... 20851 ft MSL (15241 ft AGL)
Lifted condensation level....... 21525 ft MSL (15915 ft AGL)
Lifted index.................... -0.8
K index......................... +19.7
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 -65.5 -85.9 255 34 18 1.0 0.5 M M M M M
45000 -61.8 -79.2 260 50 26 5.8 3.2 M M M M M
40000 -52.6 -62.7 260 54 28 6.2 3.4 M M M M M
38000 -48.8 -55.8 260 52 27 6.2 3.4 M M M M M
36000 -45.1 -49.2 260 50 26 7.0 3.9 M M M M M
34000 -40.4 -40.7 265 48 25 7.9 4.3 M M M M M
32000 -35.6 -32.1 265 46 24 8.3 4.5 M M M M M
30000 -31.1 -24.0 265 43 22 7.6 4.2 43.6 110.5 5.7 M M
29000 -28.8 -19.8 265 42 21 7.6 4.2 42.8 109.1 5.1 M M
28000 -26.6 -15.9 270 41 21 7.7 4.2 42.1 107.7 4.6 M M
27000 -24.3 -11.7 265 40 21 7.7 4.2 41.2 106.1 3.9 M M
26000 -22.0 -7.6 265 40 21 7.7 4.2 40.4 104.7 3.3 M M
25000 -19.7 -3.5 265 40 21 7.3 4.0 39.8 103.6 2.8 M M
24000 -17.7 0.1 260 39 20 6.9 3.8 38.6 101.5 1.8 M M
23000 -15.6 3.9 255 38 20 6.9 3.8 37.6 99.6 1.0 M M
22000 -13.1 8.4 255 37 19 7.0 3.8 36.4 97.4 -0.1 1573 8.0
21000 -11.0 12.2 250 35 18 7.0 3.8 35.3 95.6 -1.0 1482 7.5
20000 -9.0 15.8 245 34 17 7.0 3.8 34.4 93.9 -1.9 1391 7.1
19500 -7.9 17.8 240 33 17 7.6 4.2 34.0 93.2 -2.3 1345 6.8
19000 -6.8 19.8 240 33 17 7.9 4.3 33.6 92.6 -2.6 1296 6.6
18500 -5.7 21.7 240 33 17 7.9 4.4 33.3 92.0 -3.0 1247 6.3
18000 -4.5 23.9 240 33 17 8.4 4.6 33.1 91.5 -3.3 1196 6.1
17500 -3.3 26.1 240 33 17 8.4 4.6 32.8 91.1 -3.5 1145 5.8
17000 -2.0 28.4 240 33 17 8.4 4.6 32.6 90.7 -3.8 1094 5.6
16500 -0.8 30.6 240 32 17 8.4 4.6 32.4 90.3 -4.1 1042 5.3
16000 0.4 32.7 240 32 16 8.5 4.7 32.2 89.9 -4.3 991 5.0
15500 1.7 35.1 245 31 16 8.7 4.8 32.0 89.5 -4.5 937 4.8
15000 3.0 37.4 245 30 15 8.8 4.8 31.8 89.3 -4.7 882 4.5
14500 4.3 39.7 245 29 15 8.6 4.7 31.6 88.9 -4.8 828 4.2
14000 5.6 42.1 250 28 14 8.6 4.7 31.4 88.6 -5.0 774 3.9
13500 7.0 44.6 250 27 14 8.8 4.8 31.3 88.3 -5.2 720 3.7
13000 8.3 46.9 250 25 13 8.9 4.9 31.1 88.0 -5.3 664 3.4
12500 9.7 49.5 255 24 13 8.6 4.7 31.0 87.8 -5.4 609 3.1
12000 11.0 51.8 255 23 12 8.5 4.7 30.8 87.4 -5.6 555 2.8
11500 12.3 54.1 255 22 12 8.4 4.6 30.6 87.1 -5.8 501 2.5
11000 13.6 56.5 255 21 11 8.0 4.4 30.4 86.7 -6.0 448 2.3
10500 15.0 59.0 255 20 11 10.0 5.5 30.4 86.6 -6.1 390 2.0
10250 15.7 60.3 255 20 10 8.3 4.5 30.3 86.5 -6.2 363 1.8
10000 16.3 61.3 255 19 10 8.7 4.8 30.2 86.3 -6.3 336 1.7
9750 17.0 62.6 250 19 10 8.6 4.7 30.1 86.2 -6.4 309 1.6
9500 17.6 63.7 250 18 9 8.6 4.7 30.0 86.0 -6.5 282 1.4
9250 18.2 64.8 250 18 9 8.3 4.5 29.9 85.8 -6.6 256 1.3
9000 18.8 65.8 250 17 9 8.2 4.5 29.8 85.6 -6.7 230 1.2
8750 19.5 67.1 250 16 8 8.0 4.4 29.7 85.4 -6.8 204 1.0
8500 20.0 68.0 245 15 7 5.4 3.0 29.4 85.0 -7.1 182 0.9
8250 20.3 68.5 245 13 7 4.5 2.5 29.0 84.3 -7.5 165 0.8
8000 20.7 69.3 240 11 6 5.8 3.2 28.7 83.6 -7.9 146 0.7
7750 21.1 70.0 230 10 5 5.2 2.9 28.4 83.1 -8.2 127 0.6
7500 21.4 70.5 225 8 4 4.3 2.3 28.0 82.4 -8.7 109 0.6
7250 21.7 71.1 210 7 4 3.8 2.1 27.5 81.6 -9.2 94 0.5
7000 21.9 71.4 200 7 3 4.4 2.4 27.1 80.8 -9.6 79 0.4
6750 22.2 72.0 190 6 3 1.8 1.0 26.7 80.0 -10.1 63 0.3
6500 22.2 72.0 180 7 3 -1.6 -0.9 25.9 78.6 -10.9 56 0.3
6250 22.1 71.8 170 7 4 0.1 0.1 25.1 77.1 -11.7 50 0.3
6000 22.1 71.8 160 8 4 -2.0 -1.1 24.3 75.8 -12.4 43 0.2
5750 21.3 70.3 145 6 3 -24.8 -13.6 22.8 73.0 -14.0 60 0.3
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 * * * * * *
08/05/2025 at 0900 MDT | 08/05/2025 at 1200 MDT
|
CAPE... 0.0 LI... +4.6 | CAPE... 0.0 LI... +4.0
CINH... -0.2 K Index... -10.3 | CINH... -0.2 K Index... -7.3
|
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 -82.3 255 33 17 1.6 0.9 | -64.0 -83.2 255 34 18 0.9 0.5
45000 -60.1 -76.2 260 54 28 3.7 2.0 | -61.1 -78.0 260 52 27 4.2 2.3
40000 -54.1 -65.4 255 66 34 7.1 3.9 | -54.3 -65.7 255 63 32 7.5 4.1
38000 -49.2 -56.6 260 66 34 7.2 4.0 | -49.2 -56.6 255 62 32 7.6 4.2
36000 -44.9 -48.8 260 65 34 7.2 4.0 | -44.6 -48.3 260 61 31 7.6 4.2
34000 -40.5 -40.9 260 57 29 7.3 4.0 | -40.0 -40.0 260 54 28 7.6 4.2
32000 -36.1 -33.0 260 48 25 7.3 4.0 | -35.5 -31.9 260 47 24 7.7 4.2
30000 -31.7 -25.1 265 41 21 7.4 4.0 | -31.1 -24.0 255 40 21 7.2 4.0
29000 -29.5 -21.1 265 38 19 7.4 4.0 | -28.9 -20.0 255 37 19 7.2 4.0
28000 -27.3 -17.1 265 35 18 7.1 3.9 | -26.8 -16.2 255 34 18 7.0 3.9
27000 -25.2 -13.4 265 37 19 7.0 3.9 | -24.7 -12.5 255 35 18 7.0 3.9
26000 -23.1 -9.6 265 38 20 7.1 3.9 | -22.6 -8.7 255 36 19 7.0 3.9
25000 -21.0 -5.8 260 40 20 7.2 3.9 | -20.5 -4.9 260 37 19 7.1 3.9
24000 -18.8 -1.8 260 39 20 7.7 4.2 | -17.8 -0.0 260 36 19 7.2 4.0
23000 -15.9 3.4 260 38 20 7.7 4.2 | -15.6 3.9 260 35 18 7.2 4.0
22000 -13.6 7.5 260 38 19 8.0 4.4 | -13.4 7.9 260 35 18 7.9 4.3
21000 -11.2 11.8 255 37 19 8.0 4.4 | -11.0 12.2 260 35 18 7.9 4.4
20000 -8.8 16.2 250 37 19 8.0 4.4 | -8.7 16.3 260 36 19 8.0 4.4
19500 -7.6 18.3 250 37 19 8.1 4.4 | -7.5 18.5 260 36 19 8.1 4.4
19000 -6.4 20.5 250 37 19 8.1 4.4 | -6.3 20.7 260 36 19 8.2 4.5
18500 -5.1 22.8 245 37 19 8.1 4.4 | -5.0 23.0 255 36 19 8.3 4.5
18000 -3.9 25.0 245 36 19 8.2 4.5 | -3.8 25.2 255 36 19 7.8 4.3
17500 -2.7 27.1 245 36 18 8.2 4.5 | -2.7 27.1 255 35 18 7.9 4.3
17000 -1.4 29.5 245 35 18 8.1 4.4 | -1.5 29.3 255 35 18 7.7 4.2
16500 -0.3 31.5 245 35 18 7.8 4.3 | -0.3 31.5 255 34 17 7.6 4.2
16000 0.9 33.6 245 34 17 7.8 4.3 | 0.8 33.4 255 33 17 7.6 4.2
15500 2.0 35.6 245 33 17 7.4 4.1 | 1.9 35.4 250 32 16 7.6 4.2
15000 3.1 37.6 240 31 16 7.5 4.1 | 3.1 37.6 250 30 16 7.6 4.2
14500 4.2 39.6 240 30 15 7.2 4.0 | 4.2 39.6 245 29 15 7.6 4.2
14000 5.3 41.5 240 28 15 7.2 4.0 | 5.3 41.5 245 28 14 7.7 4.2
13500 6.3 43.3 240 27 14 7.3 4.0 | 6.5 43.7 240 26 13 7.7 4.2
13000 7.4 45.3 240 25 13 7.4 4.1 | 7.6 45.7 240 24 12 7.8 4.3
12500 8.5 47.3 240 23 12 7.3 4.0 | 8.8 47.8 240 22 12 7.9 4.3
12000 9.6 49.3 240 21 11 7.1 3.9 | 9.9 49.8 235 20 10 8.0 4.4
11500 10.6 51.1 240 19 10 7.3 4.0 | 11.1 52.0 235 18 9 8.3 4.5
11000 11.7 53.1 240 18 9 7.8 4.3 | 12.4 54.3 235 17 9 8.6 4.7
10500 12.9 55.2 240 16 8 6.9 3.8 | 13.7 56.7 230 15 8 6.5 3.6
10250 13.4 56.1 245 16 8 7.2 3.9 | 14.1 57.4 235 14 7 7.4 4.1
10000 14.0 57.2 245 16 8 8.6 4.7 | 14.8 58.6 235 14 7 10.8 5.9
9750 14.6 58.3 240 15 8 8.2 4.5 | 15.6 60.1 235 13 7 10.1 5.5
9500 15.2 59.4 240 14 7 8.4 4.6 | 16.3 61.3 230 13 7 9.7 5.3
9250 15.9 60.6 245 14 7 8.3 4.5 | 17.0 62.6 235 12 6 8.8 4.8
9000 16.4 61.5 245 14 7 7.2 4.0 | 17.7 63.9 235 11 6 9.0 4.9
8750 16.9 62.4 240 13 6 6.7 3.7 | 19.1 66.4 235 10 5 8.9 4.9
8500 17.5 63.5 235 12 6 6.4 3.5 | 19.7 67.5 240 9 5 8.0 4.4
8250 18.3 64.9 235 10 5 6.2 3.4 | 20.3 68.5 245 8 4 9.4 5.2
8000 18.8 65.8 230 9 5 7.1 3.9 | 21.1 70.0 240 8 4 11.1 6.1
7750 19.3 66.7 220 8 4 5.9 3.2 | 21.9 71.4 240 8 4 9.7 5.3
7500 19.7 67.5 215 7 4 4.5 2.5 | 22.6 72.7 245 8 4 8.6 4.7
7250 20.1 68.2 210 7 4 5.7 3.1 | 23.2 73.8 250 7 4 9.6 5.3
7000 20.6 69.1 205 6 3 8.4 4.6 | 24.0 75.2 245 7 4 11.5 6.3
6750 21.3 70.3 190 6 3 7.9 4.3 | 24.9 76.8 245 7 4 11.2 6.1
6500 21.8 71.2 180 6 3 6.4 3.5 | 25.7 78.3 250 7 3 11.1 6.1
6250 22.3 72.1 170 5 3 6.5 3.5 | 26.5 79.7 255 6 3 9.0 5.0
6000 22.8 73.0 165 5 3 10.3 5.6 | 27.2 81.0 255 6 3 14.3 7.9
5750 23.9 75.0 160 5 2 17.9 9.8 | 28.9 84.0 255 6 3 31.2 17.1
5500 24.9 76.8 145 4 2 3.5 1.9 | 30.9 87.6 265 5 3 8.3 4.5
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
08/05/2025 at 1500 MDT | 08/05/2025 at 1800 MDT
|
CAPE... 0.0 LI... +1.6 | CAPE... 0.0 LI... +1.4
CINH... -0.1 K Index... -4.8 | CINH... -0.0 K Index... -2.5
|
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 -64.3 -83.7 260 36 19 -0.4 -0.2 | -64.8 -84.6 265 36 18 -0.3 -0.1
45000 -62.3 -80.1 260 57 29 5.2 2.9 | -62.5 -80.5 265 58 30 5.7 3.1
40000 -53.5 -64.3 260 64 33 7.7 4.2 | -53.1 -63.6 265 62 32 7.4 4.0
38000 -48.9 -56.0 260 62 32 7.6 4.2 | -48.7 -55.7 260 59 30 7.4 4.0
36000 -44.3 -47.7 255 60 31 7.7 4.2 | -44.3 -47.7 260 56 29 7.4 4.1
34000 -39.7 -39.5 260 54 28 7.8 4.3 | -39.8 -39.6 260 51 26 7.5 4.1
32000 -35.0 -31.0 260 48 25 7.9 4.3 | -35.2 -31.4 260 47 24 7.7 4.2
30000 -30.8 -23.4 260 44 23 7.0 3.8 | -31.0 -23.8 260 44 23 7.0 3.9
29000 -28.7 -19.7 255 42 22 7.0 3.8 | -28.9 -20.0 260 42 22 7.0 3.9
28000 -26.6 -15.9 255 41 21 7.0 3.8 | -26.8 -16.2 255 41 21 7.2 4.0
27000 -24.5 -12.1 255 40 20 7.0 3.8 | -24.6 -12.3 255 39 20 7.2 4.0
26000 -22.4 -8.3 255 39 20 7.0 3.8 | -22.4 -8.3 255 37 19 7.2 4.0
25000 -20.3 -4.5 250 38 19 7.0 3.8 | -19.7 -3.5 255 35 18 7.4 4.1
24000 -17.7 0.1 255 36 18 7.1 3.9 | -17.5 0.5 255 33 17 7.4 4.1
23000 -15.6 3.9 255 34 18 7.1 3.9 | -15.3 4.5 255 31 16 7.4 4.1
22000 -13.4 7.9 255 33 17 8.0 4.4 | -13.0 8.6 255 29 15 7.8 4.3
21000 -11.1 12.0 255 32 16 7.9 4.3 | -10.7 12.7 255 28 14 7.8 4.3
20000 -8.7 16.3 255 31 16 7.9 4.4 | -8.3 17.1 255 26 14 7.8 4.3
19500 -7.6 18.3 255 31 16 8.1 4.4 | -7.2 19.0 255 26 13 7.9 4.3
19000 -6.3 20.7 255 30 15 8.2 4.5 | -6.0 21.2 255 25 13 8.0 4.4
18500 -5.1 22.8 255 30 15 8.2 4.5 | -4.8 23.4 255 24 13 8.0 4.4
18000 -3.9 25.0 255 29 15 8.4 4.6 | -3.6 25.5 255 24 12 8.3 4.6
17500 -2.6 27.3 255 29 15 8.4 4.6 | -2.4 27.7 255 23 12 8.3 4.6
17000 -1.4 29.5 250 28 14 8.5 4.6 | -1.1 30.0 250 23 12 8.6 4.7
16500 -0.1 31.8 250 27 14 8.5 4.7 | 0.2 32.4 250 23 12 8.8 4.8
16000 1.2 34.2 250 27 14 8.5 4.7 | 1.5 34.7 250 22 11 8.9 4.9
15500 2.5 36.5 250 26 13 8.8 4.8 | 2.8 37.0 250 22 11 9.3 5.1
15000 3.8 38.8 245 25 13 8.7 4.8 | 4.2 39.6 250 22 11 9.2 5.1
14500 5.1 41.2 245 25 13 9.1 5.0 | 5.6 42.1 245 22 11 9.5 5.2
14000 6.5 43.7 245 24 12 9.2 5.0 | 7.0 44.6 245 21 11 9.5 5.2
13500 7.8 46.0 240 24 12 9.2 5.0 | 8.4 47.1 245 21 11 9.5 5.2
13000 9.2 48.6 240 23 12 9.2 5.0 | 9.9 49.8 245 21 11 9.5 5.2
12500 10.6 51.1 240 22 12 9.3 5.1 | 11.3 52.3 245 21 11 9.4 5.2
12000 12.0 53.6 240 22 11 9.3 5.1 | 12.7 54.9 250 20 11 9.4 5.1
11500 13.4 56.1 240 21 11 9.3 5.1 | 14.1 57.4 250 20 10 9.4 5.2
11000 14.7 58.5 240 21 11 9.0 5.0 | 15.5 59.9 250 20 10 9.4 5.2
10500 16.1 61.0 240 20 10 7.5 4.1 | 16.9 62.4 250 19 10 7.9 4.4
10250 16.6 61.9 245 19 10 7.8 4.3 | 17.4 63.3 250 19 10 8.3 4.5
10000 17.3 63.1 245 19 10 10.1 5.5 | 18.2 64.8 250 19 10 10.5 5.7
9750 18.0 64.4 245 18 9 9.5 5.2 | 18.9 66.0 250 18 10 10.0 5.5
9500 18.7 65.7 245 18 9 9.4 5.2 | 19.7 67.5 250 18 9 9.6 5.3
9250 19.4 66.9 250 17 9 9.2 5.0 | 20.4 68.7 250 18 9 9.0 4.9
9000 20.1 68.2 250 17 9 9.5 5.2 | 21.1 70.0 250 17 9 9.1 5.0
8750 21.6 70.9 250 17 9 9.4 5.1 | 22.4 72.3 255 16 8 8.9 4.9
8500 22.2 72.0 255 17 9 8.7 4.8 | 23.1 73.6 255 16 8 8.1 4.4
8250 22.9 73.2 255 17 9 9.9 5.4 | 23.7 74.7 255 16 8 9.5 5.2
8000 23.7 74.7 255 16 8 11.4 6.3 | 24.5 76.1 255 16 8 11.2 6.1
7750 24.5 76.1 255 16 8 9.7 5.3 | 25.3 77.5 255 15 8 9.5 5.2
7500 25.2 77.4 255 16 8 8.0 4.4 | 25.9 78.6 255 15 8 8.0 4.4
7250 25.8 78.4 260 16 8 9.6 5.3 | 26.6 79.9 260 15 8 9.3 5.1
7000 26.6 79.9 260 16 8 12.2 6.7 | 27.3 81.1 260 15 8 11.4 6.3
6750 27.6 81.7 260 15 8 11.5 6.3 | 28.2 82.8 260 14 7 10.9 6.0
6500 28.4 83.1 260 15 8 10.9 6.0 | 29.0 84.2 260 14 7 10.2 5.6
6250 29.2 84.6 260 15 8 9.1 5.0 | 29.7 85.5 260 14 7 9.5 5.2
6000 29.9 85.8 260 15 8 14.6 8.0 | 30.4 86.7 260 14 7 11.0 6.0
5750 31.6 88.9 260 13 7 32.0 17.6 | 31.5 88.7 260 12 6 18.5 10.1
5500 33.8 92.8 265 13 7 15.6 8.6 | 32.9 91.2 265 11 6 16.2 8.9
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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