Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
087
UXUS97 KGJT 031306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Sunday, August 3, 2025
This forecast is for Sunday, August 3, 2025:
If the trigger temperature of 84.8 F/29.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1402 ft/min (7.1 m/s)
Maximum height of thermals.................. 20384 ft MSL (14777 ft AGL)
Forecast maximum temperature................... 96.0 F/36.0 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................. 16587 ft MSL (10980 ft AGL)
Thermal soaring outlook for Monday 08/04....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:17:02 / 20:23:34 MDT
Total possible sunshine........... 14 hr 6 min 32 sec (846 min 32 sec)
Altitude of sun at 13:20:18 MDT... 67.72 degrees
Upper air data from rawinsonde observation taken on 08/03/2025 at 0600 MDT
Freezing level.................. 16274 ft MSL (10667 ft AGL)
Convective condensation level... 25566 ft MSL (19959 ft AGL)
Lifted condensation level....... 24339 ft MSL (18731 ft AGL)
Lifted index.................... +2.4
K index......................... -2.0
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 -63.2 -81.8 255 23 12 1.4 0.7 M M M M M
45000 -59.8 -75.6 270 42 21 4.5 2.4 M M M M M
40000 -52.7 -62.9 275 65 34 6.5 3.6 M M M M M
38000 -48.8 -55.8 275 63 33 6.6 3.6 M M M M M
36000 -44.4 -47.9 270 61 31 6.7 3.7 M M M M M
34000 -40.2 -40.4 275 58 30 7.1 3.9 M M M M M
32000 -35.9 -32.6 275 56 29 7.4 4.0 M M M M M
30000 -30.9 -23.6 275 52 27 8.5 4.6 43.7 110.6 6.2 M M
29000 -28.4 -19.1 275 50 26 8.5 4.6 43.2 109.8 5.9 M M
28000 -25.9 -14.6 270 48 25 7.2 3.9 42.8 109.0 5.6 M M
27000 -23.8 -10.8 270 45 23 6.9 3.8 41.5 106.8 4.7 M M
26000 -21.8 -7.2 265 42 21 6.9 3.8 40.5 104.8 3.9 M M
25000 -19.7 -3.5 265 39 20 6.9 3.8 39.5 103.1 3.2 M M
24000 -17.5 0.5 260 36 18 7.3 4.0 38.5 101.3 2.4 M M
23000 -15.3 4.5 260 33 17 7.3 4.0 37.6 99.7 1.7 M M
22000 -13.1 8.4 255 30 16 7.5 4.1 36.8 98.3 1.0 M M
21000 -10.8 12.6 250 28 15 8.0 4.4 36.1 97.0 0.4 M M
20000 -7.8 18.0 240 27 14 7.9 4.4 35.4 95.6 -0.3 1351 6.9
19500 -6.6 20.1 240 27 14 7.6 4.2 35.1 95.2 -0.5 1301 6.6
19000 -5.6 21.9 235 26 13 7.0 3.8 34.6 94.3 -0.9 1255 6.4
18500 -4.5 23.9 230 25 13 7.0 3.9 34.1 93.5 -1.3 1209 6.1
18000 -3.5 25.7 225 24 12 6.8 3.7 33.7 92.6 -1.8 1164 5.9
17500 -2.5 27.5 220 23 12 6.8 3.7 33.2 91.7 -2.3 1119 5.7
17000 -1.5 29.3 220 22 11 7.2 3.9 32.7 90.8 -2.7 1074 5.5
16500 -0.4 31.3 220 21 11 7.8 4.3 32.3 90.2 -3.1 1025 5.2
16000 0.8 33.4 220 20 10 7.7 4.2 32.0 89.6 -3.4 976 5.0
15500 2.0 35.6 225 19 10 8.8 4.8 31.7 89.1 -3.7 925 4.7
15000 3.3 37.9 230 20 10 8.7 4.8 31.6 88.8 -3.9 871 4.4
14500 4.6 40.3 230 20 10 8.8 4.8 31.4 88.5 -4.1 817 4.2
14000 5.9 42.6 235 20 10 8.8 4.9 31.2 88.2 -4.2 763 3.9
13500 7.2 45.0 235 20 10 8.9 4.9 31.1 88.0 -4.4 709 3.6
13000 8.6 47.5 240 19 10 9.0 4.9 31.0 87.8 -4.5 654 3.3
12500 9.9 49.8 240 19 10 8.9 4.9 30.9 87.6 -4.7 598 3.0
12000 11.2 52.2 240 19 10 8.7 4.8 30.7 87.2 -4.9 545 2.8
11500 12.5 54.5 240 19 10 8.5 4.7 30.5 87.0 -5.0 491 2.5
11000 13.7 56.7 245 18 9 7.6 4.2 30.2 86.4 -5.3 440 2.2
10500 15.0 59.0 245 17 9 10.6 5.8 30.1 86.1 -5.5 387 2.0
10250 15.8 60.4 245 17 9 9.3 5.1 30.1 86.2 -5.5 356 1.8
10000 16.3 61.3 245 16 8 7.3 4.0 30.0 85.9 -5.7 331 1.7
9750 16.9 62.4 245 15 8 7.5 4.1 29.8 85.6 -5.9 307 1.6
9500 17.5 63.5 245 15 8 8.5 4.7 29.6 85.4 -6.0 282 1.4
9250 18.2 64.8 240 14 7 8.1 4.5 29.6 85.2 -6.1 255 1.3
9000 18.7 65.7 240 13 7 6.6 3.6 29.4 84.8 -6.3 232 1.2
8750 19.2 66.6 235 12 6 7.2 4.0 29.1 84.5 -6.5 208 1.1
8500 19.7 67.5 230 11 6 6.3 3.5 28.9 84.1 -6.8 185 0.9
8250 20.1 68.2 220 10 5 5.0 2.7 28.6 83.5 -7.1 166 0.8
8000 20.5 68.9 210 9 5 4.7 2.6 28.2 82.8 -7.5 148 0.7
7750 20.9 69.6 200 9 5 5.1 2.8 27.8 82.1 -7.9 129 0.7
7500 21.2 70.2 190 9 5 3.8 2.1 27.5 81.4 -8.3 111 0.6
7250 21.4 70.5 175 11 5 2.1 1.1 26.9 80.5 -8.8 98 0.5
7000 21.6 70.9 170 12 6 1.8 1.0 26.3 79.4 -9.4 86 0.4
6750 21.7 71.1 160 11 6 1.5 0.8 25.7 78.3 -10.1 76 0.4
6500 21.6 70.9 155 11 6 -4.9 -2.7 24.9 76.9 -10.9 70 0.4
6250 20.9 69.6 145 10 5 -12.4 -6.8 23.5 74.2 -12.4 85 0.4
6000 20.2 68.4 135 9 5 0.4 0.2 22.1 71.8 -13.8 97 0.5
5750 20.4 68.7 125 8 4 -7.4 -4.0 21.5 70.8 -14.4 84 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 * * * * * *
08/03/2025 at 0900 MDT | 08/03/2025 at 1200 MDT
|
CAPE... 0.0 LI... +1.5 | CAPE... +0.3 LI... +1.4
CINH... 0.0 K Index... +9.6 | CINH... -0.4 K Index... +8.5
|
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 -61.2 -78.2 290 23 12 4.2 2.3 | -63.0 -81.4 290 22 11 3.0 1.6
45000 -55.6 -68.1 295 50 26 2.9 1.6 | -57.7 -71.9 295 46 24 4.2 2.3
40000 -50.7 -59.3 300 80 41 5.9 3.3 | -51.0 -59.8 295 64 33 6.2 3.4
38000 -47.1 -52.8 300 82 42 6.0 3.3 | -47.3 -53.1 295 66 34 6.2 3.4
36000 -43.0 -45.4 305 85 44 6.1 3.3 | -43.6 -46.5 295 68 35 6.1 3.4
34000 -39.3 -38.7 305 78 40 6.3 3.4 | -39.5 -39.1 300 66 34 6.8 3.7
32000 -35.5 -31.9 300 70 36 6.2 3.4 | -35.4 -31.7 300 64 33 6.7 3.7
30000 -31.5 -24.7 300 61 32 6.9 3.8 | -31.0 -23.8 300 57 29 7.4 4.1
29000 -29.4 -20.9 300 57 29 6.9 3.8 | -28.8 -19.8 300 52 27 7.4 4.1
28000 -27.3 -17.1 300 53 27 6.8 3.7 | -26.6 -15.9 300 48 25 7.1 3.9
27000 -25.3 -13.5 300 48 25 6.6 3.6 | -24.0 -11.2 300 43 22 6.8 3.7
26000 -23.3 -9.9 300 44 22 6.6 3.6 | -22.0 -7.6 300 39 20 6.8 3.7
25000 -21.4 -6.5 300 39 20 6.7 3.7 | -19.9 -3.8 300 35 18 6.3 3.4
24000 -19.7 -3.5 300 35 18 5.4 3.0 | -18.2 -0.8 300 32 16 5.8 3.2
23000 -18.1 -0.6 295 31 16 5.4 3.0 | -16.5 2.3 295 29 15 5.8 3.2
22000 -16.0 3.2 285 26 14 6.9 3.8 | -14.7 5.5 295 27 14 6.1 3.4
21000 -13.8 7.2 285 24 12 7.3 4.0 | -12.8 9.0 290 24 12 6.3 3.4
20000 -11.7 10.9 280 22 11 7.4 4.1 | -11.0 12.2 285 22 11 6.4 3.5
19500 -10.6 12.9 280 21 11 7.8 4.3 | -10.1 13.8 285 20 10 6.7 3.7
19000 -9.4 15.1 280 20 10 8.5 4.6 | -9.0 15.8 280 19 10 7.7 4.2
18500 -8.1 17.4 280 19 10 8.4 4.6 | -7.8 18.0 280 18 9 7.6 4.2
18000 -6.9 19.6 285 18 9 8.7 4.8 | -6.7 19.9 280 17 9 8.5 4.7
17500 -5.6 21.9 285 17 9 8.7 4.8 | -5.4 22.3 275 16 8 8.6 4.7
17000 -4.3 24.3 285 17 9 8.8 4.8 | -4.1 24.6 275 16 8 8.7 4.8
16500 -2.9 26.8 290 16 8 9.0 4.9 | -2.8 27.0 275 15 8 8.8 4.8
16000 -1.6 29.1 290 16 8 9.0 4.9 | -1.5 29.3 280 14 7 8.8 4.8
15500 -0.3 31.5 295 16 8 9.0 4.9 | -0.2 31.6 280 13 7 8.7 4.8
15000 1.0 33.8 295 15 8 9.0 4.9 | 1.1 34.0 280 13 6 8.7 4.8
14500 2.4 36.3 300 15 8 9.0 5.0 | 2.4 36.3 285 12 6 9.0 5.0
14000 3.7 38.7 300 14 7 9.0 5.0 | 3.7 38.7 285 11 6 9.1 5.0
13500 5.1 41.2 305 13 7 8.9 4.9 | 5.1 41.2 290 10 5 9.1 5.0
13000 6.4 43.5 305 12 6 8.8 4.9 | 6.4 43.5 295 9 5 9.1 5.0
12500 7.7 45.9 310 11 5 8.6 4.7 | 7.8 46.0 300 8 4 9.1 5.0
12000 8.9 48.0 310 9 5 8.3 4.6 | 9.1 48.4 300 7 4 9.1 5.0
11500 10.1 50.2 310 7 4 8.2 4.5 | 10.5 50.9 305 7 3 9.1 5.0
11000 11.3 52.3 315 6 3 8.0 4.4 | 11.8 53.2 305 6 3 8.9 4.9
10500 12.5 54.5 320 4 2 7.2 3.9 | 13.2 55.8 310 5 3 7.4 4.1
10250 12.9 55.2 320 4 2 7.3 4.0 | 13.7 56.7 305 4 2 7.8 4.3
10000 13.6 56.5 325 3 2 8.6 4.7 | 14.4 57.9 305 4 2 10.1 5.5
9750 14.2 57.6 330 3 2 8.2 4.5 | 15.1 59.2 310 3 2 9.6 5.3
9500 14.8 58.6 340 3 1 8.5 4.6 | 15.8 60.4 310 3 2 9.3 5.1
9250 15.4 59.7 350 2 1 8.5 4.7 | 16.5 61.7 305 3 1 8.7 4.8
9000 16.0 60.8 360 2 1 7.1 3.9 | 17.8 64.0 305 2 1 9.2 5.0
8750 16.5 61.7 010 2 1 6.4 3.5 | 18.4 65.1 305 2 1 8.2 4.5
8500 17.4 63.3 030 1 1 5.8 3.2 | 18.9 66.0 305 2 1 6.2 3.4
8250 17.8 64.0 050 1 1 5.9 3.2 | 19.4 66.9 300 2 1 8.7 4.8
8000 18.2 64.8 060 1 1 6.3 3.5 | 20.3 68.5 300 2 1 12.1 6.6
7750 18.6 65.5 070 2 1 4.0 2.2 | 21.1 70.0 300 2 1 9.4 5.2
7500 18.8 65.8 085 2 1 1.8 1.0 | 21.7 71.1 300 2 1 6.8 3.7
7250 19.0 66.2 095 2 1 3.1 1.7 | 22.2 72.0 295 2 1 9.0 4.9
7000 19.3 66.7 100 3 1 5.6 3.1 | 23.0 73.4 295 2 1 12.8 7.0
6750 19.8 67.6 100 3 1 5.6 3.1 | 24.0 75.2 295 2 1 11.6 6.3
6500 20.1 68.2 105 3 2 4.4 2.4 | 24.8 76.6 290 1 1 9.9 5.4
6250 20.5 68.9 105 3 2 4.9 2.7 | 25.5 77.9 285 1 1 8.8 4.8
6000 21.0 69.8 100 3 2 10.6 5.8 | 26.2 79.2 285 1 1 14.9 8.2
5750 22.1 71.8 105 3 2 19.3 10.6 | 28.0 82.4 285 1 1 31.4 17.2
5500 23.2 73.8 105 3 2 1.9 1.0 | 29.9 85.8 285 1 1 6.7 3.7
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
08/03/2025 at 1500 MDT | 08/03/2025 at 1800 MDT
|
CAPE... 0.0 LI... +2.1 | CAPE... 0.0 LI... +1.8
CINH... -0.0 K Index... +6.0 | CINH... 0.0 K Index... +5.8
|
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 -63.2 -81.8 275 17 9 2.1 1.2 | -62.7 -80.9 250 19 10 2.1 1.1
45000 -58.5 -73.3 285 36 18 4.6 2.5 | -58.5 -73.3 270 36 18 3.9 2.1
40000 -51.4 -60.5 285 56 29 5.9 3.3 | -52.1 -61.8 280 54 28 6.3 3.5
38000 -47.8 -54.0 290 59 30 5.9 3.3 | -48.4 -55.1 280 57 29 6.3 3.5
36000 -44.2 -47.6 290 62 32 6.1 3.3 | -44.6 -48.3 285 59 30 6.4 3.5
34000 -39.9 -39.8 290 61 31 7.4 4.0 | -40.2 -40.4 285 58 30 7.3 4.0
32000 -35.4 -31.7 295 59 30 7.3 4.0 | -35.8 -32.4 285 57 29 7.2 3.9
30000 -30.7 -23.3 295 52 27 7.9 4.3 | -31.1 -24.0 290 50 26 7.9 4.3
29000 -28.3 -18.9 300 47 24 7.9 4.3 | -28.8 -19.8 295 47 24 7.9 4.3
28000 -26.0 -14.8 300 43 22 7.2 4.0 | -26.4 -15.5 295 43 22 7.7 4.2
27000 -23.4 -10.1 300 37 19 6.8 3.7 | -23.5 -10.3 295 39 20 7.6 4.2
26000 -21.3 -6.3 295 33 17 6.8 3.7 | -21.3 -6.3 290 35 18 7.6 4.2
25000 -19.3 -2.7 290 29 15 6.4 3.5 | -19.0 -2.2 290 32 16 7.1 3.9
24000 -17.4 0.7 295 27 14 6.2 3.4 | -16.9 1.6 290 31 16 6.9 3.8
23000 -15.6 3.9 295 26 13 6.2 3.4 | -14.8 5.4 290 30 15 6.9 3.8
22000 -13.7 7.3 300 24 12 6.8 3.7 | -12.8 9.0 290 28 14 6.9 3.8
21000 -11.6 11.1 300 21 11 7.0 3.8 | -10.7 12.7 290 23 12 7.0 3.8
20000 -9.5 14.9 300 18 9 7.0 3.8 | -8.7 16.3 295 18 9 7.0 3.9
19500 -8.5 16.7 300 16 8 7.0 3.8 | -7.6 18.3 295 15 8 7.2 3.9
19000 -7.5 18.5 295 15 8 7.0 3.8 | -6.5 20.3 295 13 7 7.5 4.1
18500 -6.5 20.3 295 14 7 6.9 3.8 | -5.4 22.3 295 11 6 7.5 4.1
18000 -5.4 22.3 290 12 6 8.1 4.5 | -4.3 24.3 290 9 5 8.5 4.7
17500 -4.2 24.4 285 12 6 8.3 4.5 | -3.0 26.6 285 8 4 8.6 4.7
17000 -3.0 26.6 280 11 6 8.5 4.6 | -1.8 28.8 275 7 4 8.7 4.8
16500 -1.7 28.9 280 11 6 8.8 4.8 | -0.5 31.1 275 7 4 8.8 4.8
16000 -0.4 31.3 275 10 5 8.8 4.8 | 0.8 33.4 270 7 4 8.8 4.8
15500 1.0 33.8 275 10 5 9.4 5.1 | 2.2 36.0 270 7 4 9.2 5.0
15000 2.4 36.3 275 10 5 9.3 5.1 | 3.5 38.3 270 7 4 9.1 5.0
14500 3.7 38.7 275 10 5 9.5 5.2 | 4.9 40.8 270 7 4 9.3 5.1
14000 5.2 41.4 275 10 5 9.5 5.2 | 6.3 43.3 270 7 4 9.3 5.1
13500 6.6 43.9 275 10 5 9.4 5.2 | 7.7 45.9 275 7 4 9.3 5.1
13000 8.0 46.4 275 10 5 9.3 5.1 | 9.1 48.4 275 7 4 9.3 5.1
12500 9.4 48.9 280 10 5 9.3 5.1 | 10.5 50.9 275 7 4 9.3 5.1
12000 10.8 51.4 280 10 5 9.2 5.1 | 11.9 53.4 275 7 3 9.2 5.1
11500 12.1 53.8 280 10 5 9.2 5.1 | 13.3 55.9 280 7 3 9.3 5.1
11000 13.5 56.3 280 10 5 9.1 5.0 | 14.7 58.5 280 7 3 9.3 5.1
10500 14.9 58.8 280 9 5 6.6 3.6 | 16.1 61.0 280 7 3 7.0 3.9
10250 15.3 59.5 285 9 5 7.4 4.1 | 16.5 61.7 285 7 3 7.4 4.1
10000 16.1 61.0 285 9 5 11.3 6.2 | 17.3 63.1 280 7 3 10.8 5.9
9750 16.9 62.4 285 9 5 10.5 5.7 | 18.0 64.4 280 7 4 10.0 5.5
9500 17.7 63.9 285 9 4 9.8 5.4 | 18.8 65.8 280 7 4 9.7 5.3
9250 18.4 65.1 285 9 4 8.8 4.8 | 19.5 67.1 280 7 4 8.8 4.8
9000 19.8 67.6 285 8 4 10.5 5.7 | 20.8 69.4 280 7 4 9.7 5.3
8750 20.5 68.9 285 8 4 9.5 5.2 | 21.6 70.9 280 7 4 9.1 5.0
8500 21.1 70.0 285 8 4 7.2 4.0 | 22.2 72.0 280 7 3 7.5 4.1
8250 21.7 71.1 290 8 4 9.5 5.2 | 22.7 72.9 285 7 3 9.0 5.0
8000 22.6 72.7 285 8 4 12.8 7.0 | 23.5 74.3 280 7 3 11.4 6.3
7750 23.5 74.3 285 8 4 10.1 5.6 | 24.3 75.7 280 7 3 9.7 5.3
7500 24.1 75.4 285 8 4 7.6 4.2 | 25.0 77.0 280 7 3 7.9 4.3
7250 24.7 76.5 290 8 4 9.3 5.1 | 25.6 78.1 285 7 4 8.8 4.8
7000 25.5 77.9 290 8 4 12.7 6.9 | 26.4 79.5 285 7 3 11.9 6.5
6750 26.5 79.7 285 7 4 11.7 6.4 | 27.3 81.1 280 7 3 11.2 6.2
6500 27.3 81.1 290 8 4 10.3 5.6 | 28.0 82.4 280 7 3 9.8 5.4
6250 28.1 82.6 290 8 4 9.2 5.0 | 28.8 83.8 285 7 3 9.5 5.2
6000 28.8 83.8 290 7 4 14.2 7.8 | 29.5 85.1 285 7 3 10.7 5.9
5750 30.5 86.9 290 7 3 30.5 16.7 | 30.5 86.9 280 6 3 18.0 9.9
5500 32.7 90.9 290 7 3 19.4 10.6 | 32.2 90.0 285 6 3 24.7 13.5
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.
042613