Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
587
UXUS97 KGJT 081305
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
705 AM MDT Friday, August 8, 2025
This forecast is for Friday, August 8, 2025:
If the trigger temperature of 80.5 F/26.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1671 ft/min (8.5 m/s)
Maximum height of thermals.................. 23426 ft MSL (17818 ft AGL)
Forecast maximum temperature................... 98.0 F/37.1 C
Time of trigger temperature.................... 0845 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................. 20402 ft MSL (14794 ft AGL)
Thermal soaring outlook for Saturday 08/09..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:21:34 / 20:17:53 MDT
Total possible sunshine........... 13 hr 56 min 19 sec (836 min 19 sec)
Altitude of sun at 13:19:44 MDT... 66.38 degrees
Upper air data from rawinsonde observation taken on 08/08/2025 at 0600 MDT
Freezing level.................. 15877 ft MSL (10269 ft AGL)
Convective condensation level... 19212 ft MSL (13604 ft AGL)
Lifted condensation level....... 21051 ft MSL (15443 ft AGL)
Lifted index.................... -2.6
K index......................... +17.0
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 -63.1 -81.6 290 28 14 -0.2 -0.1 M M M M M
45000 -61.6 -78.9 280 39 20 4.0 2.2 M M M M M
40000 -55.1 -67.2 280 43 22 7.0 3.8 M M M M M
38000 -50.9 -59.6 280 42 22 7.1 3.9 M M M M M
36000 -46.6 -51.9 280 41 21 7.0 3.8 M M M M M
34000 -41.6 -42.9 280 41 21 8.7 4.8 M M M M M
32000 -35.8 -32.4 280 41 21 8.7 4.8 M M M M M
30000 -30.9 -23.6 280 40 21 8.1 4.5 43.9 111.0 5.5 M M
29000 -28.4 -19.1 275 39 20 8.1 4.5 43.3 109.9 5.1 M M
28000 -26.0 -14.8 275 38 20 7.2 3.9 42.8 109.0 4.7 M M
27000 -24.0 -11.2 275 38 20 6.8 3.8 41.5 106.7 3.8 M M
26000 -22.0 -7.6 270 38 20 6.9 3.8 40.4 104.8 2.9 M M
25000 -20.0 -4.0 270 38 20 6.8 3.7 39.5 103.1 2.1 M M
24000 -18.3 -0.9 265 36 18 5.5 3.0 37.9 100.2 0.8 M M
23000 -16.7 1.9 265 33 17 5.5 3.0 36.4 97.4 -0.5 1641 8.3
22000 -15.1 4.8 260 30 16 6.0 3.3 34.9 94.9 -1.8 1564 7.9
21000 -12.9 8.8 265 29 15 7.8 4.3 34.1 93.4 -2.5 1468 7.5
20000 -10.6 12.9 270 29 15 7.8 4.3 33.4 92.1 -3.2 1369 7.0
19500 -9.4 15.1 270 29 15 7.8 4.3 33.1 91.6 -3.5 1320 6.7
19000 -8.2 17.2 270 29 15 8.5 4.6 32.8 91.1 -3.7 1269 6.4
18500 -6.3 20.7 270 29 15 8.5 4.7 32.5 90.5 -4.1 1190 6.0
18000 -5.1 22.8 270 29 15 8.2 4.5 32.3 90.1 -4.3 1138 5.8
17500 -3.9 25.0 270 29 15 8.2 4.5 32.0 89.6 -4.6 1087 5.5
17000 -2.6 27.3 270 28 15 8.3 4.6 31.8 89.2 -4.8 1036 5.3
16500 -1.4 29.5 265 28 14 8.6 4.7 31.6 88.8 -5.0 983 5.0
16000 -0.1 31.8 265 27 14 8.6 4.7 31.4 88.5 -5.3 930 4.7
15500 1.1 34.0 265 27 14 8.5 4.7 31.2 88.1 -5.5 878 4.5
15000 2.4 36.3 265 25 13 8.5 4.7 31.0 87.7 -5.7 825 4.2
14500 3.7 38.7 260 24 12 8.3 4.6 30.8 87.4 -5.9 773 3.9
14000 4.9 40.8 260 22 12 8.3 4.5 30.5 86.9 -6.2 721 3.7
13500 6.1 43.0 260 21 11 8.2 4.5 30.3 86.5 -6.5 670 3.4
13000 7.3 45.1 260 19 10 8.0 4.4 30.0 86.0 -6.8 620 3.2
12500 8.4 47.1 260 16 8 8.1 4.4 29.7 85.5 -7.1 570 2.9
12000 9.6 49.3 260 14 7 8.1 4.4 29.5 85.0 -7.4 520 2.6
11500 10.8 51.4 260 12 6 7.8 4.3 29.2 84.6 -7.7 469 2.4
11000 11.8 53.2 260 10 5 6.1 3.3 28.7 83.7 -8.2 425 2.2
10500 12.8 55.0 260 8 4 8.8 4.9 28.3 82.9 -8.7 380 1.9
10250 13.5 56.3 260 7 3 8.5 4.7 28.2 82.8 -8.8 351 1.8
10000 14.1 57.4 260 6 3 6.6 3.6 28.0 82.4 -9.0 328 1.7
9750 14.6 58.3 255 5 3 7.3 4.0 27.8 82.1 -9.2 305 1.5
9500 15.1 59.2 250 4 2 6.3 3.5 27.6 81.7 -9.4 282 1.4
9250 15.6 60.1 240 4 2 6.7 3.7 27.3 81.2 -9.7 261 1.3
9000 16.1 61.0 230 3 2 7.7 4.2 27.1 80.9 -9.9 237 1.2
8750 16.7 62.1 215 2 1 7.6 4.2 27.0 80.5 -10.1 212 1.1
8500 17.3 63.1 190 2 1 7.1 3.9 26.8 80.2 -10.3 188 1.0
8250 17.7 63.9 160 2 1 5.9 3.3 26.5 79.8 -10.6 167 0.8
8000 18.1 64.6 130 2 1 5.6 3.1 26.2 79.2 -10.9 147 0.7
7750 18.5 65.3 110 2 1 5.9 3.2 25.9 78.7 -11.3 127 0.6
7500 19.0 66.2 095 3 1 5.1 2.8 25.6 78.1 -11.6 107 0.5
7250 19.3 66.7 090 3 2 3.9 2.2 25.2 77.4 -12.0 90 0.5
7000 19.6 67.3 090 4 2 3.3 1.8 24.8 76.6 -12.5 74 0.4
6750 19.8 67.6 090 4 2 2.6 1.4 24.2 75.6 -13.1 61 0.3
6500 19.9 67.8 090 4 2 -1.1 -0.6 23.6 74.5 -13.7 51 0.3
6250 19.6 67.3 095 5 2 -5.5 -3.0 22.6 72.6 -14.8 52 0.3
6000 19.3 66.7 095 5 3 2.7 1.5 21.6 70.9 -15.8 52 0.3
5750 19.6 67.3 100 5 3 -3.2 -1.8 21.2 70.1 -16.3 36 0.2
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 * * * * * *
08/08/2025 at 0900 MDT | 08/08/2025 at 1200 MDT
|
CAPE... 0.0 LI... +4.0 | CAPE... 0.0 LI... +2.6
CINH... -1.5 K Index... +9.7 | CINH... -0.1 K Index... +11.6
|
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 -62.9 -81.2 270 33 17 1.2 0.7 | -63.8 -82.8 270 30 16 0.4 0.2
45000 -60.3 -76.5 270 46 24 3.0 1.6 | -61.6 -78.9 270 42 22 4.0 2.2
40000 -55.2 -67.4 260 47 24 7.4 4.1 | -55.0 -67.0 265 41 21 7.7 4.2
38000 -50.8 -59.4 260 46 24 7.4 4.1 | -50.3 -58.5 260 40 20 7.8 4.3
36000 -45.8 -50.4 255 45 23 7.5 4.1 | -45.0 -49.0 260 39 20 7.8 4.3
34000 -41.0 -41.8 255 46 24 8.0 4.4 | -40.3 -40.5 260 41 21 7.8 4.3
32000 -36.2 -33.2 255 47 24 7.9 4.3 | -35.7 -32.3 260 43 22 7.7 4.2
30000 -31.5 -24.7 255 46 24 7.9 4.3 | -31.0 -23.8 255 44 23 7.8 4.3
29000 -29.2 -20.6 255 45 23 7.9 4.3 | -28.7 -19.7 255 45 23 7.8 4.3
28000 -26.8 -16.2 260 44 23 7.4 4.1 | -26.4 -15.5 255 45 23 7.1 3.9
27000 -24.6 -12.3 260 44 23 7.3 4.0 | -24.4 -11.9 255 45 23 6.8 3.7
26000 -22.5 -8.5 260 43 22 7.3 4.0 | -22.4 -8.3 255 45 23 6.8 3.7
25000 -20.3 -4.5 260 43 22 7.3 4.0 | -20.4 -4.7 255 44 23 6.8 3.7
24000 -18.1 -0.6 260 42 22 7.4 4.1 | -18.4 -1.1 255 44 23 6.8 3.8
23000 -15.3 4.5 255 42 22 7.4 4.1 | -16.3 2.7 255 43 22 6.9 3.8
22000 -13.1 8.4 255 42 21 7.3 4.0 | -13.7 7.3 255 43 22 7.3 4.0
21000 -10.9 12.4 250 42 22 7.3 4.0 | -11.5 11.3 255 43 22 7.4 4.1
20000 -8.8 16.2 245 43 22 7.3 4.0 | -9.3 15.3 255 43 22 7.4 4.1
19500 -7.7 18.1 245 43 22 7.3 4.0 | -8.3 17.1 255 44 22 7.5 4.1
19000 -6.6 20.1 245 44 22 7.3 4.0 | -7.1 19.2 250 43 22 7.6 4.2
18500 -5.5 22.1 245 44 22 7.3 4.0 | -6.0 21.2 250 43 22 7.6 4.2
18000 -4.5 23.9 240 44 22 7.6 4.1 | -4.9 23.2 250 42 22 7.7 4.2
17500 -3.3 26.1 240 43 22 7.6 4.2 | -3.8 25.2 250 41 21 7.7 4.2
17000 -2.2 28.0 240 43 22 7.7 4.2 | -2.6 27.3 250 40 21 7.8 4.3
16500 -1.1 30.0 240 42 21 8.0 4.4 | -1.5 29.3 250 39 20 8.1 4.4
16000 0.1 32.2 240 41 21 8.0 4.4 | -0.3 31.5 250 37 19 8.0 4.4
15500 1.3 34.3 245 39 20 7.9 4.3 | 0.9 33.6 250 36 19 8.4 4.6
15000 2.4 36.3 245 37 19 7.9 4.3 | 2.2 36.0 250 34 18 8.4 4.6
14500 3.6 38.5 245 36 18 7.8 4.3 | 3.4 38.1 250 33 17 8.7 4.8
14000 4.7 40.5 245 33 17 7.7 4.2 | 4.7 40.5 250 32 16 8.8 4.8
13500 5.9 42.6 250 31 16 7.8 4.3 | 6.0 42.8 250 30 16 8.9 4.9
13000 7.0 44.6 250 29 15 7.9 4.3 | 7.4 45.3 250 29 15 9.1 5.0
12500 8.2 46.8 250 28 14 8.1 4.4 | 8.7 47.7 250 28 15 9.1 5.0
12000 9.5 49.1 255 26 13 8.6 4.7 | 10.1 50.2 250 27 14 9.0 4.9
11500 10.7 51.3 255 25 13 8.6 4.7 | 11.4 52.5 250 26 14 9.0 5.0
11000 12.0 53.6 255 24 12 8.7 4.8 | 12.8 55.0 250 25 13 9.3 5.1
10500 13.3 55.9 255 23 12 6.9 3.8 | 14.2 57.6 250 25 13 7.4 4.1
10250 13.8 56.8 260 23 12 7.4 4.1 | 14.7 58.5 250 25 13 7.9 4.3
10000 14.5 58.1 260 22 11 10.2 5.6 | 15.4 59.7 250 24 12 10.7 5.9
9750 15.2 59.4 260 22 11 9.5 5.2 | 16.2 61.2 250 24 12 10.0 5.5
9500 15.9 60.6 255 21 11 9.7 5.3 | 16.9 62.4 250 23 12 10.1 5.5
9250 16.6 61.9 255 21 11 9.2 5.1 | 17.7 63.9 250 23 12 9.7 5.3
9000 17.3 63.1 260 21 11 8.4 4.6 | 18.4 65.1 255 22 11 9.5 5.2
8750 17.9 64.2 255 20 10 8.2 4.5 | 19.1 66.4 255 22 11 9.5 5.2
8500 19.1 66.4 255 19 10 7.6 4.1 | 19.8 67.6 255 21 11 9.4 5.2
8250 19.6 67.3 255 18 10 7.4 4.1 | 20.5 68.9 255 21 11 8.4 4.6
8000 20.2 68.4 250 17 9 7.8 4.3 | 21.9 71.4 255 20 10 11.8 6.5
7750 20.8 69.4 250 15 8 6.8 3.7 | 22.8 73.0 255 19 10 10.1 5.5
7500 21.2 70.2 250 14 7 5.3 2.9 | 23.4 74.1 255 19 10 8.0 4.4
7250 21.6 70.9 250 13 7 5.8 3.2 | 24.0 75.2 255 20 10 8.9 4.9
7000 22.1 71.8 245 11 6 7.9 4.3 | 24.8 76.6 255 19 10 12.3 6.8
6750 22.7 72.9 240 9 5 7.9 4.4 | 25.8 78.4 255 18 9 11.8 6.5
6500 23.2 73.8 235 8 4 7.2 4.0 | 26.6 79.9 255 18 9 10.4 5.7
6250 23.8 74.8 235 7 4 6.8 3.7 | 27.4 81.3 255 18 9 9.7 5.3
6000 24.3 75.7 230 6 3 9.1 5.0 | 28.1 82.6 255 17 9 13.0 7.1
5750 25.2 77.4 225 5 3 17.0 9.3 | 29.5 85.1 255 15 8 27.2 14.9
5500 26.6 79.9 225 4 2 15.0 8.2 | 32.0 89.6 260 14 7 35.9 19.7
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
08/08/2025 at 1500 MDT | 08/08/2025 at 1800 MDT
|
CAPE... 0.0 LI... +1.1 | CAPE... +1.2 LI... +0.1
CINH... -1.6 K Index... +10.4 | CINH... -0.6 K Index... +12.4
|
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 -64.2 -83.6 275 30 15 -0.5 -0.3 | -64.0 -83.2 275 30 15 -0.4 -0.2
45000 -62.5 -80.5 275 40 21 4.9 2.7 | -62.4 -80.3 275 43 22 4.7 2.6
40000 -54.7 -66.5 270 40 21 7.7 4.2 | -54.8 -66.6 275 46 24 7.7 4.2
38000 -50.0 -58.0 270 41 21 7.8 4.3 | -50.2 -58.4 275 45 23 7.7 4.3
36000 -44.8 -48.6 265 42 22 7.7 4.2 | -45.0 -49.0 275 44 23 7.7 4.2
34000 -40.3 -40.5 265 42 22 7.4 4.1 | -40.5 -40.9 270 44 23 7.5 4.1
32000 -35.9 -32.6 265 43 22 7.3 4.0 | -36.0 -32.8 270 45 23 7.3 4.0
30000 -31.4 -24.5 265 44 23 7.6 4.2 | -31.6 -24.9 270 45 23 7.4 4.1
29000 -29.1 -20.4 260 45 23 7.6 4.2 | -29.3 -20.7 270 45 23 7.4 4.1
28000 -26.8 -16.2 260 46 24 7.2 3.9 | -27.1 -16.8 270 44 23 7.3 4.0
27000 -24.7 -12.5 260 45 23 7.1 3.9 | -25.0 -13.0 270 44 23 7.3 4.0
26000 -22.6 -8.7 260 45 23 7.1 3.9 | -22.8 -9.0 270 43 22 7.3 4.0
25000 -20.5 -4.9 260 44 23 7.1 3.9 | -20.6 -5.1 270 42 22 7.2 4.0
24000 -18.5 -1.3 260 43 22 7.0 3.8 | -18.6 -1.5 265 40 21 6.6 3.6
23000 -16.4 2.5 260 41 21 7.0 3.8 | -16.7 1.9 260 38 20 6.7 3.7
22000 -13.8 7.2 255 39 20 7.4 4.1 | -14.2 6.4 255 36 18 8.1 4.4
21000 -11.6 11.1 255 37 19 7.5 4.1 | -11.7 10.9 255 34 17 8.3 4.5
20000 -9.4 15.1 255 34 18 7.5 4.1 | -9.3 15.3 255 32 16 8.3 4.6
19500 -8.2 17.2 255 33 17 7.7 4.2 | -8.1 17.4 255 31 16 8.7 4.8
19000 -7.1 19.2 255 32 17 8.1 4.4 | -6.7 19.9 255 30 15 9.3 5.1
18500 -5.9 21.4 255 32 16 8.0 4.4 | -5.3 22.5 255 29 15 9.3 5.1
18000 -4.7 23.5 255 31 16 8.8 4.8 | -3.9 25.0 255 29 15 9.4 5.2
17500 -3.3 26.1 255 30 16 8.8 4.8 | -2.5 27.5 255 28 15 9.4 5.2
17000 -2.0 28.4 255 30 15 9.0 4.9 | -1.1 30.0 255 28 14 9.5 5.2
16500 -0.7 30.7 255 29 15 9.2 5.1 | 0.3 32.5 255 28 14 9.7 5.3
16000 0.7 33.3 250 29 15 9.3 5.1 | 1.8 35.2 255 27 14 9.7 5.3
15500 2.0 35.6 250 29 15 9.1 5.0 | 3.2 37.8 255 27 14 9.4 5.1
15000 3.4 38.1 250 28 15 9.1 5.0 | 4.6 40.3 255 27 14 9.4 5.2
14500 4.8 40.6 250 28 14 9.3 5.1 | 6.0 42.8 255 26 14 9.6 5.2
14000 6.1 43.0 250 28 14 9.3 5.1 | 7.4 45.3 255 26 14 9.6 5.3
13500 7.5 45.5 250 27 14 9.3 5.1 | 8.9 48.0 255 26 13 9.6 5.2
13000 8.9 48.0 250 27 14 9.3 5.1 | 10.3 50.5 255 26 13 9.5 5.2
12500 10.3 50.5 250 27 14 9.4 5.2 | 11.7 53.1 255 26 13 9.5 5.2
12000 11.7 53.1 250 26 14 9.7 5.3 | 13.1 55.6 260 25 13 9.7 5.3
11500 13.2 55.8 250 26 13 9.5 5.2 | 14.6 58.3 260 25 13 9.6 5.2
11000 14.5 58.1 250 26 13 8.5 4.7 | 15.8 60.4 260 25 13 8.1 4.4
10500 15.7 60.3 255 25 13 11.0 6.0 | 17.0 62.6 260 25 13 12.2 6.7
10250 16.7 62.1 255 25 13 11.7 6.4 | 18.1 64.6 260 23 12 13.2 7.2
10000 17.4 63.3 255 24 12 9.0 4.9 | 18.8 65.8 260 23 12 8.4 4.6
9750 18.1 64.6 255 24 12 9.8 5.4 | 19.5 67.1 260 23 12 10.0 5.5
9500 18.8 65.8 255 24 12 9.5 5.2 | 20.3 68.5 260 23 12 8.6 4.7
9250 19.5 67.1 255 23 12 9.7 5.3 | 20.9 69.6 260 23 12 7.9 4.3
9000 20.3 68.5 255 23 12 9.9 5.4 | 21.5 70.7 265 22 11 9.6 5.2
8750 21.0 69.8 255 23 12 10.0 5.5 | 22.3 72.1 265 21 11 10.4 5.7
8500 21.7 71.1 255 23 12 9.8 5.4 | 23.0 73.4 265 20 11 10.1 5.6
8250 22.4 72.3 255 23 12 8.5 4.7 | 23.7 74.7 265 20 10 8.5 4.7
8000 23.9 75.0 260 22 11 11.5 6.3 | 25.1 77.2 265 20 10 11.0 6.0
7750 24.7 76.5 260 22 11 10.2 5.6 | 25.9 78.6 265 19 10 10.1 5.6
7500 25.4 77.7 260 22 11 8.1 4.4 | 26.6 79.9 265 18 9 8.4 4.6
7250 26.0 78.8 260 22 11 8.8 4.8 | 27.2 81.0 270 19 10 8.6 4.7
7000 26.8 80.2 260 21 11 12.3 6.7 | 28.0 82.4 270 18 9 11.0 6.0
6750 27.7 81.9 260 20 10 11.9 6.5 | 28.8 83.8 265 17 9 11.1 6.1
6500 28.5 83.3 260 20 10 10.4 5.7 | 29.6 85.3 270 17 9 10.4 5.7
6250 29.3 84.7 260 20 10 10.2 5.6 | 30.4 86.7 270 17 9 10.6 5.8
6000 30.1 86.2 265 20 10 11.3 6.2 | 31.1 88.0 270 16 8 8.3 4.5
5750 31.2 88.2 260 17 9 22.9 12.6 | 31.7 89.1 270 14 7 10.2 5.6
5500 34.0 93.2 265 16 8 56.2 30.8 | 33.6 92.5 270 13 7 50.2 27.5
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.
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