Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
887
UXUS97 KGJT 021306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Saturday, August 2, 2025
This forecast is for Saturday, August 2, 2025:
If the trigger temperature of 82.1 F/27.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1710 ft/min (8.7 m/s)
Maximum height of thermals.................. 23154 ft MSL (17545 ft AGL)
Forecast maximum temperature................... 95.0 F/35.5 C
Time of trigger temperature.................... 1015 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................. 20026 ft MSL (14417 ft AGL)
Thermal soaring outlook for Sunday 08/03....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:16:08 / 20:24:38 MDT
Total possible sunshine........... 14 hr 8 min 30 sec (848 min 30 sec)
Altitude of sun at 13:20:23 MDT... 67.97 degrees
Upper air data from rawinsonde observation taken on 08/02/2025 at 0600 MDT
Freezing level.................. 15608 ft MSL (9999 ft AGL)
Convective condensation level... 19742 ft MSL (14133 ft AGL)
Lifted condensation level....... 21341 ft MSL (15732 ft AGL)
Lifted index.................... -1.8
K index......................... +7.9
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 -61.1 -78.0 300 30 16 3.7 2.0 M M M M M
45000 -55.7 -68.3 295 59 30 3.0 1.6 M M M M M
40000 -50.8 -59.4 295 84 43 5.6 3.0 M M M M M
38000 -47.4 -53.3 300 84 43 5.6 3.1 M M M M M
36000 -44.0 -47.2 300 83 43 5.6 3.1 M M M M M
34000 -39.8 -39.6 300 75 39 6.5 3.6 M M M M M
32000 -35.9 -32.6 295 67 34 6.3 3.5 M M M M M
30000 -31.4 -24.5 295 61 31 7.6 4.1 43.4 110.1 6.4 M M
29000 -29.2 -20.6 295 58 30 7.6 4.1 42.6 108.7 5.9 M M
28000 -26.9 -16.4 300 56 29 6.5 3.5 41.8 107.3 5.3 M M
27000 -25.2 -13.4 295 50 26 6.0 3.3 40.3 104.5 4.2 M M
26000 -23.4 -10.1 295 45 23 6.0 3.3 38.9 101.9 3.1 M M
25000 -21.6 -6.9 290 39 20 6.0 3.3 37.6 99.6 2.1 M M
24000 -19.7 -3.5 290 36 19 6.3 3.4 36.2 97.2 1.0 M M
23000 -17.8 -0.0 290 33 17 6.3 3.5 34.9 94.9 -0.1 1702 8.6
22000 -16.0 3.2 285 31 16 6.5 3.6 33.8 92.8 -1.1 1617 8.2
21000 -13.9 7.0 285 28 14 7.1 3.9 32.7 90.9 -2.0 1526 7.8
20000 -11.9 10.6 285 25 13 7.1 3.9 31.8 89.2 -2.9 1435 7.3
19500 -10.3 13.5 290 23 12 7.9 4.3 31.2 88.1 -3.5 1366 6.9
19000 -9.0 15.8 290 22 11 8.8 4.8 31.0 87.8 -3.7 1313 6.7
18500 -7.7 18.1 290 21 11 8.8 4.8 30.8 87.5 -3.9 1259 6.4
18000 -6.4 20.5 290 20 10 9.2 5.0 30.7 87.3 -4.1 1204 6.1
17500 -5.0 23.0 290 19 10 9.2 5.0 30.6 87.1 -4.2 1148 5.8
17000 -3.6 25.5 295 19 10 9.2 5.0 30.5 86.9 -4.3 1092 5.5
16500 -2.3 27.9 295 18 9 9.1 5.0 30.4 86.7 -4.4 1036 5.3
16000 -0.9 30.4 295 18 9 9.2 5.0 30.3 86.5 -4.5 981 5.0
15500 0.5 32.9 300 17 9 9.3 5.1 30.2 86.4 -4.6 925 4.7
15000 1.8 35.2 300 16 8 9.3 5.1 30.1 86.2 -4.7 869 4.4
14500 3.2 37.8 300 16 8 9.1 5.0 30.0 86.1 -4.8 813 4.1
14000 4.6 40.3 300 15 7 9.1 5.0 29.9 85.9 -5.0 758 3.8
13500 5.9 42.6 300 13 7 8.8 4.8 29.8 85.7 -5.1 703 3.6
13000 7.2 45.0 305 12 6 8.7 4.8 29.6 85.3 -5.3 649 3.3
12500 8.5 47.3 310 10 5 8.7 4.7 29.5 85.1 -5.5 596 3.0
12000 9.7 49.5 315 9 4 8.5 4.7 29.3 84.7 -5.8 544 2.8
11500 11.0 51.8 320 7 4 8.2 4.5 29.1 84.4 -6.0 491 2.5
11000 12.1 53.8 330 7 3 7.5 4.1 28.8 83.8 -6.4 442 2.2
10500 13.4 56.1 340 6 3 10.6 5.8 28.6 83.4 -6.6 390 2.0
10250 14.2 57.6 345 6 3 9.7 5.3 28.7 83.6 -6.5 359 1.8
10000 14.8 58.6 350 5 3 8.0 4.4 28.5 83.4 -6.7 333 1.7
9750 15.4 59.7 355 5 3 8.8 4.8 28.4 83.2 -6.8 307 1.6
9500 16.0 60.8 360 5 2 7.2 4.0 28.3 83.0 -6.9 281 1.4
9250 16.5 61.7 360 4 2 6.9 3.8 28.1 82.5 -7.2 260 1.3
9000 17.0 62.6 005 4 2 7.9 4.3 27.9 82.3 -7.4 236 1.2
8750 17.6 63.7 010 4 2 8.3 4.5 27.8 82.0 -7.6 211 1.1
8500 18.2 64.8 015 3 2 5.7 3.1 27.6 81.7 -7.8 187 1.0
8250 18.4 65.1 025 3 2 3.8 2.1 27.2 80.9 -8.2 172 0.9
8000 18.8 65.8 035 3 1 5.3 2.9 26.8 80.2 -8.6 154 0.8
7750 19.2 66.6 050 2 1 5.1 2.8 26.4 79.6 -9.0 135 0.7
7500 19.5 67.1 060 2 1 3.8 2.1 26.1 78.9 -9.4 118 0.6
7250 19.7 67.5 075 2 1 2.6 1.4 25.5 78.0 -10.0 103 0.5
7000 19.9 67.8 090 3 1 3.1 1.7 25.0 77.0 -10.5 90 0.5
6750 20.1 68.2 095 3 1 0.9 0.5 24.5 76.0 -11.1 77 0.4
6500 20.0 68.0 095 3 2 -2.8 -1.5 23.6 74.5 -11.9 72 0.4
6250 19.7 67.5 095 4 2 -5.3 -2.9 22.6 72.7 -13.0 74 0.4
6000 19.5 67.1 095 5 3 2.3 1.3 21.6 70.9 -14.0 74 0.4
5750 19.7 67.5 100 5 3 -5.9 -3.2 21.1 69.9 -14.6 61 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 * * * * * *
08/02/2025 at 0900 MDT | 08/02/2025 at 1200 MDT
|
CAPE... +39.8 LI... -0.5 | CAPE... +167.6 LI... -1.2
CINH... -112.4 K Index... +23.5 | CINH... -9.5 K Index... +24.0
|
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 -61.7 -79.1 250 24 13 2.9 1.6 | -61.3 -78.3 250 27 14 3.0 1.6
45000 -56.1 -69.0 260 48 25 5.4 2.9 | -55.9 -68.6 260 48 25 4.8 2.6
40000 -48.4 -55.1 265 67 35 3.1 1.7 | -48.9 -56.0 265 65 34 3.7 2.0
38000 -46.3 -51.3 265 70 36 3.1 1.7 | -46.4 -51.5 265 70 36 3.6 2.0
36000 -44.5 -48.1 270 73 37 3.6 2.0 | -44.3 -47.7 265 75 39 3.9 2.1
34000 -40.6 -41.1 265 70 36 6.7 3.7 | -40.8 -41.4 260 71 36 5.9 3.2
32000 -36.6 -33.9 260 67 34 6.6 3.6 | -37.3 -35.1 260 66 34 5.7 3.1
30000 -32.3 -26.1 260 61 31 7.1 3.9 | -32.9 -27.2 260 59 30 7.6 4.2
29000 -30.2 -22.4 260 58 30 7.1 3.9 | -30.6 -23.1 260 56 29 7.6 4.2
28000 -28.1 -18.6 260 54 28 6.7 3.7 | -28.3 -18.9 260 52 27 7.3 4.0
27000 -26.1 -15.0 260 50 26 6.5 3.6 | -26.2 -15.2 260 48 25 7.1 3.9
26000 -24.2 -11.6 260 46 24 6.5 3.6 | -24.0 -11.2 260 44 23 7.1 3.9
25000 -22.2 -8.0 260 42 22 6.6 3.6 | -21.9 -7.4 255 41 21 7.0 3.9
24000 -19.6 -3.3 255 37 19 7.3 4.0 | -19.9 -3.8 255 38 20 6.5 3.6
23000 -17.4 0.7 255 33 17 7.3 4.0 | -17.5 0.5 250 35 18 6.6 3.6
22000 -15.2 4.6 245 30 15 7.1 3.9 | -15.5 4.1 245 33 17 7.4 4.1
21000 -13.2 8.2 245 28 14 7.1 3.9 | -13.4 7.9 240 31 16 7.5 4.1
20000 -11.1 12.0 240 27 14 7.2 3.9 | -11.2 11.8 235 30 15 7.5 4.1
19500 -10.0 14.0 235 26 13 7.6 4.1 | -10.1 13.8 235 29 15 7.9 4.4
19000 -8.9 16.0 235 26 13 8.0 4.4 | -8.9 16.0 235 28 14 8.4 4.6
18500 -7.8 18.0 230 25 13 8.0 4.4 | -7.6 18.3 235 27 14 8.5 4.6
18000 -6.6 20.1 230 25 13 8.6 4.7 | -6.5 20.3 230 26 14 7.9 4.3
17500 -5.3 22.5 230 25 13 8.6 4.7 | -5.3 22.5 230 26 13 8.0 4.4
17000 -4.1 24.6 230 24 12 8.9 4.9 | -4.1 24.6 230 25 13 8.4 4.6
16500 -2.8 27.0 230 23 12 9.2 5.0 | -2.9 26.8 230 25 13 8.7 4.8
16000 -1.4 29.5 230 22 12 9.3 5.1 | -1.6 29.1 225 24 12 8.8 4.8
15500 -0.1 31.8 230 22 11 9.4 5.2 | -0.3 31.5 225 23 12 9.4 5.1
15000 1.3 34.3 230 21 11 9.4 5.2 | 1.1 34.0 225 23 12 9.3 5.1
14500 2.8 37.0 230 20 10 9.4 5.1 | 2.4 36.3 225 22 11 9.3 5.1
14000 4.2 39.6 235 19 10 9.4 5.2 | 3.8 38.8 225 21 11 9.4 5.1
13500 5.5 41.9 235 18 9 9.1 5.0 | 5.2 41.4 225 21 11 9.4 5.1
13000 6.9 44.4 240 18 9 9.0 5.0 | 6.6 43.9 230 20 10 9.4 5.1
12500 8.2 46.8 240 17 9 8.9 4.9 | 8.0 46.4 230 19 10 9.3 5.1
12000 9.5 49.1 245 17 9 8.9 4.9 | 9.4 48.9 230 19 10 9.3 5.1
11500 10.8 51.4 245 17 9 8.8 4.8 | 10.8 51.4 230 18 9 9.4 5.1
11000 12.1 53.8 250 17 9 8.6 4.7 | 12.2 54.0 235 17 9 9.4 5.2
10500 13.4 56.1 250 16 8 7.2 4.0 | 13.6 56.5 235 17 9 9.7 5.3
10250 13.9 57.0 250 16 8 6.9 3.8 | 14.3 57.7 235 15 8 9.6 5.3
10000 14.5 58.1 250 15 8 8.6 4.7 | 15.0 59.0 235 15 8 9.2 5.1
9750 15.1 59.2 245 14 7 8.3 4.5 | 15.7 60.3 235 15 8 9.0 5.0
9500 15.7 60.3 245 14 7 8.0 4.4 | 16.4 61.5 235 15 8 10.3 5.6
9250 16.3 61.3 245 13 7 7.4 4.1 | 17.2 63.0 240 14 7 10.9 6.0
9000 16.8 62.2 245 12 6 7.0 3.8 | 17.9 64.2 240 13 7 9.1 5.0
8750 17.3 63.1 240 11 6 6.6 3.6 | 18.6 65.5 240 13 7 8.6 4.7
8500 18.3 64.9 230 10 5 7.1 3.9 | 19.8 67.6 245 12 6 8.6 4.7
8250 18.8 65.8 230 10 5 6.3 3.5 | 20.5 68.9 245 12 6 9.8 5.4
8000 19.2 66.6 220 9 5 5.2 2.8 | 21.3 70.3 245 12 6 11.0 6.0
7750 19.5 67.1 210 9 5 5.3 2.9 | 22.1 71.8 245 11 6 9.5 5.2
7500 19.9 67.8 200 9 4 5.2 2.9 | 22.7 72.9 245 11 6 8.4 4.6
7250 20.3 68.5 195 8 4 5.7 3.1 | 23.4 74.1 250 11 6 10.0 5.5
7000 20.8 69.4 185 8 4 6.9 3.8 | 24.2 75.6 250 11 5 12.2 6.7
6750 21.3 70.3 180 8 4 6.8 3.8 | 25.1 77.2 250 10 5 11.1 6.1
6500 21.7 71.1 175 7 4 6.7 3.7 | 25.9 78.6 250 10 5 10.8 5.9
6250 22.2 72.0 170 6 3 6.2 3.4 | 26.7 80.1 255 10 5 8.9 4.9
6000 22.7 72.9 155 6 3 10.7 5.9 | 27.4 81.3 250 9 5 16.1 8.9
5750 23.9 75.0 150 6 3 20.1 11.0 | 29.4 84.9 255 9 5 34.5 18.9
5500 25.1 77.2 145 5 3 3.0 1.6 | 31.3 88.3 260 9 4 -0.1 -0.0
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
08/02/2025 at 1500 MDT | 08/02/2025 at 1800 MDT
|
CAPE... +96.9 LI... 0.0 | CAPE... +40.7 LI... +0.1
CINH... -17.7 K Index... +17.7 | CINH... -17.7 K Index... +14.2
|
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 -60.4 -76.7 260 28 15 3.2 1.7 | -59.9 -75.8 270 30 16 3.5 1.9
45000 -54.9 -66.8 265 51 26 4.6 2.5 | -54.6 -66.3 275 54 28 3.7 2.0
40000 -48.3 -54.9 265 69 36 3.3 1.8 | -49.0 -56.2 275 73 38 3.7 2.0
38000 -46.1 -51.0 270 74 38 3.3 1.8 | -46.5 -51.7 280 75 39 3.7 2.0
36000 -44.1 -47.4 270 78 40 3.3 1.8 | -44.3 -47.7 280 78 40 3.7 2.0
34000 -41.0 -41.8 265 72 37 5.3 2.9 | -41.2 -42.2 275 70 36 5.3 2.9
32000 -37.8 -36.0 260 65 33 5.1 2.8 | -38.0 -36.4 275 61 31 5.2 2.9
30000 -33.7 -28.7 260 57 29 7.3 4.0 | -34.0 -29.2 275 53 27 6.9 3.8
29000 -31.5 -24.7 260 53 27 7.3 4.0 | -31.9 -25.4 270 48 25 6.9 3.8
28000 -29.3 -20.7 260 49 25 7.1 3.9 | -29.8 -21.6 270 44 23 7.4 4.1
27000 -27.2 -17.0 255 46 24 7.1 3.9 | -27.5 -17.5 270 42 21 7.7 4.2
26000 -25.1 -13.2 255 43 22 7.1 3.9 | -25.2 -13.4 270 39 20 7.8 4.3
25000 -23.0 -9.4 250 40 20 7.1 3.9 | -22.9 -9.2 265 36 19 7.7 4.2
24000 -20.3 -4.5 245 37 19 7.3 4.0 | -20.8 -5.4 265 33 17 7.1 3.9
23000 -18.1 -0.6 245 34 18 7.4 4.0 | -18.2 -0.8 265 30 15 7.2 3.9
22000 -15.9 3.4 240 32 16 8.5 4.6 | -16.0 3.2 260 27 14 8.8 4.8
21000 -13.4 7.9 240 31 16 8.5 4.7 | -13.3 8.1 260 27 14 8.9 4.9
20000 -10.9 12.4 240 30 15 8.6 4.7 | -10.7 12.7 255 26 13 8.9 4.9
19500 -9.6 14.7 235 29 15 8.8 4.8 | -9.4 15.1 255 26 13 9.0 4.9
19000 -8.3 17.1 235 28 15 9.0 4.9 | -8.0 17.6 250 25 13 9.1 5.0
18500 -7.0 19.4 235 28 14 9.0 4.9 | -6.7 19.9 250 24 13 9.1 5.0
18000 -5.7 21.7 235 27 14 9.1 5.0 | -5.3 22.5 250 24 12 9.3 5.1
17500 -4.3 24.3 235 27 14 9.1 5.0 | -3.9 25.0 250 24 12 9.3 5.1
17000 -3.0 26.6 235 26 13 9.3 5.1 | -2.5 27.5 250 23 12 9.5 5.2
16500 -1.6 29.1 235 26 13 9.4 5.1 | -1.1 30.0 250 23 12 9.6 5.3
16000 -0.2 31.6 235 25 13 9.4 5.2 | 0.3 32.5 250 23 12 9.6 5.3
15500 1.2 34.2 235 25 13 9.5 5.2 | 1.7 35.1 250 23 12 9.4 5.2
15000 2.6 36.7 235 25 13 9.5 5.2 | 3.1 37.6 250 22 12 9.5 5.2
14500 4.0 39.2 235 24 13 9.4 5.2 | 4.6 40.3 250 22 11 9.5 5.2
14000 5.4 41.7 235 24 12 9.4 5.2 | 6.0 42.8 250 22 11 9.5 5.2
13500 6.8 44.2 235 24 12 9.3 5.1 | 7.4 45.3 250 22 11 9.5 5.2
13000 8.2 46.8 235 23 12 9.2 5.1 | 8.8 47.8 250 21 11 9.5 5.2
12500 9.6 49.3 235 23 12 9.3 5.1 | 10.2 50.4 250 21 11 9.6 5.2
12000 11.0 51.8 240 23 12 9.4 5.1 | 11.7 53.1 250 21 11 9.6 5.3
11500 12.4 54.3 240 22 12 9.3 5.1 | 13.1 55.6 250 21 11 9.6 5.3
11000 13.7 56.7 240 22 11 9.1 5.0 | 14.5 58.1 255 20 10 9.3 5.1
10500 15.1 59.2 245 21 11 8.1 4.5 | 15.9 60.6 255 20 10 7.0 3.8
10250 15.7 60.3 245 21 11 8.7 4.8 | 16.3 61.3 255 20 10 7.6 4.2
10000 16.4 61.5 245 21 11 10.5 5.7 | 17.1 62.8 255 19 10 11.1 6.1
9750 17.2 63.0 250 21 11 9.9 5.4 | 17.9 64.2 255 19 10 10.3 5.6
9500 17.9 64.2 250 21 11 10.4 5.7 | 18.7 65.7 255 19 10 9.9 5.4
9250 18.7 65.7 250 21 11 10.5 5.7 | 19.4 66.9 260 18 9 9.3 5.1
9000 19.4 66.9 250 21 11 9.8 5.4 | 20.1 68.2 260 18 9 9.7 5.3
8750 20.2 68.4 250 21 11 9.8 5.4 | 20.8 69.4 260 18 9 9.9 5.4
8500 21.5 70.7 255 21 11 7.9 4.3 | 21.5 70.7 260 17 9 9.4 5.2
8250 22.2 72.0 255 21 11 10.0 5.5 | 22.8 73.0 265 17 9 9.7 5.3
8000 23.0 73.4 255 20 11 12.1 6.6 | 23.6 74.5 265 17 9 11.6 6.4
7750 23.8 74.8 255 20 10 9.6 5.3 | 24.5 76.1 265 16 8 9.6 5.3
7500 24.5 76.1 255 20 10 7.7 4.2 | 25.1 77.2 265 16 8 7.7 4.2
7250 25.1 77.2 255 20 11 9.7 5.3 | 25.7 78.3 265 16 8 9.3 5.1
7000 25.9 78.6 255 20 10 12.5 6.9 | 26.5 79.7 265 16 8 11.9 6.5
6750 26.9 80.4 255 19 10 11.6 6.3 | 27.4 81.3 265 15 8 11.1 6.1
6500 27.7 81.9 260 19 10 10.9 6.0 | 28.1 82.6 265 15 8 10.1 5.5
6250 28.5 83.3 260 19 10 9.1 5.0 | 28.9 84.0 270 15 8 9.3 5.1
6000 29.2 84.6 260 18 9 15.6 8.6 | 29.6 85.3 270 14 7 11.4 6.3
5750 31.1 88.0 260 16 8 34.3 18.8 | 30.8 87.4 270 13 7 20.5 11.2
5500 33.2 91.8 260 16 8 7.4 4.1 | 32.3 90.1 270 12 6 16.4 9.0
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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