Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
971
UXUS97 KGJT 291306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Tuesday, July 29, 2025
This forecast is for Tuesday, July 29, 2025:
If the trigger temperature of 82.5 F/28.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1720 ft/min (8.7 m/s)
Maximum height of thermals.................. 23583 ft MSL (17974 ft AGL)
Forecast maximum temperature................... 98.0 F/37.1 C
Time of trigger temperature.................... 0930 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................. 19737 ft MSL (14128 ft AGL)
Thermal soaring outlook for Wednesday 07/30.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:12:35 / 20:28:40 MDT
Total possible sunshine........... 14 hr 16 min 5 sec (856 min 5 sec)
Altitude of sun at 13:20:37 MDT... 68.95 degrees
Upper air data from rawinsonde observation taken on 07/29/2025 at 0600 MDT
Freezing level.................. 16331 ft MSL (10722 ft AGL)
Convective condensation level... 16937 ft MSL (11328 ft AGL)
Lifted condensation level....... 18821 ft MSL (13212 ft AGL)
Lifted index.................... -6.0
K index......................... +16.6
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 -60.4 -76.7 235 25 13 1.2 0.7 M M M M M
45000 -58.0 -72.4 230 38 20 2.1 1.2 M M M M M
40000 -54.2 -65.6 225 43 22 6.0 3.3 M M M M M
38000 -50.6 -59.1 225 40 21 6.1 3.3 M M M M M
36000 -46.9 -52.4 225 38 20 5.9 3.3 M M M M M
34000 -42.5 -44.5 230 34 17 7.6 4.2 M M M M M
32000 -37.4 -35.3 230 29 15 7.8 4.3 M M M M M
30000 -32.5 -26.5 240 27 14 8.2 4.5 41.6 107.0 3.8 M M
29000 -30.0 -22.0 245 26 13 8.2 4.5 41.1 106.0 3.4 M M
28000 -27.6 -17.7 245 25 13 7.5 4.1 40.5 105.0 3.0 M M
27000 -25.4 -13.7 250 24 12 7.6 4.1 39.6 103.3 2.3 M M
26000 -23.1 -9.6 255 23 12 7.6 4.1 38.8 101.8 1.7 M M
25000 -20.9 -5.6 265 22 11 7.5 4.1 38.1 100.6 1.1 M M
24000 -18.7 -1.7 265 19 10 7.4 4.1 37.1 98.8 0.3 M M
23000 -16.5 2.3 265 17 9 7.4 4.1 36.3 97.3 -0.4 1669 8.5
22000 -14.3 6.3 270 14 7 7.3 4.0 35.5 96.0 -1.0 1574 8.0
21000 -12.1 10.2 260 13 6 7.3 4.0 34.6 94.2 -1.9 1480 7.5
20000 -10.0 14.0 250 11 6 7.4 4.1 33.7 92.7 -2.7 1387 7.0
19500 -8.9 16.0 245 11 6 7.6 4.2 33.4 92.1 -3.1 1340 6.8
19000 -7.7 18.1 245 11 6 8.9 4.9 33.1 91.7 -3.4 1289 6.5
18500 -5.8 21.6 240 11 6 8.8 4.8 32.9 91.2 -3.6 1209 6.1
18000 -4.4 24.1 240 11 6 9.3 5.1 32.8 91.0 -3.8 1154 5.9
17500 -3.1 26.4 240 11 6 9.3 5.1 32.7 90.9 -3.9 1098 5.6
17000 -1.7 28.9 240 11 6 9.5 5.2 32.7 90.8 -4.0 1041 5.3
16500 -0.3 31.5 240 11 5 9.5 5.2 32.6 90.7 -4.0 984 5.0
16000 1.2 34.2 240 11 5 9.3 5.1 32.6 90.6 -4.1 927 4.7
15500 2.5 36.5 240 10 5 8.9 4.9 32.4 90.4 -4.2 872 4.4
15000 3.8 38.8 240 10 5 8.9 4.9 32.3 90.1 -4.4 817 4.2
14500 5.1 41.2 235 10 5 8.3 4.6 32.1 89.8 -4.6 764 3.9
14000 6.3 43.3 235 9 5 8.4 4.6 31.9 89.4 -4.8 713 3.6
13500 7.6 45.7 230 9 5 8.2 4.5 31.7 89.0 -5.1 661 3.4
13000 8.8 47.8 230 9 4 8.2 4.5 31.4 88.5 -5.4 610 3.1
12500 9.9 49.8 230 8 4 7.9 4.3 31.2 88.1 -5.7 560 2.8
12000 11.1 52.0 230 8 4 7.7 4.2 30.8 87.5 -6.1 512 2.6
11500 12.2 54.0 230 8 4 7.4 4.0 30.5 86.9 -6.4 464 2.4
11000 13.1 55.6 235 9 5 6.9 3.8 30.1 86.1 -7.0 420 2.1
10500 14.3 57.7 235 9 5 8.5 4.7 29.8 85.7 -7.3 371 1.9
10250 14.8 58.6 235 9 5 7.2 3.9 29.6 85.3 -7.6 349 1.8
10000 15.3 59.5 235 10 5 7.3 4.0 29.4 85.0 -7.8 326 1.7
9750 15.8 60.4 235 10 5 7.7 4.2 29.2 84.6 -8.1 304 1.5
9500 16.3 61.3 230 10 5 6.1 3.4 29.1 84.3 -8.3 282 1.4
9250 16.6 61.9 230 10 5 5.7 3.1 28.7 83.7 -8.7 264 1.3
9000 17.1 62.8 225 10 5 7.0 3.9 28.5 83.3 -9.0 243 1.2
8750 17.6 63.7 220 10 5 6.7 3.7 28.3 82.9 -9.3 221 1.1
8500 18.0 64.4 215 10 5 6.5 3.6 28.0 82.4 -9.6 199 1.0
8250 18.5 65.3 210 10 5 5.7 3.1 27.7 81.9 -9.9 179 0.9
8000 18.9 66.0 205 10 5 5.2 2.9 27.4 81.3 -10.2 160 0.8
7750 19.2 66.6 200 9 5 5.1 2.8 27.1 80.7 -10.6 141 0.7
7500 19.6 67.3 195 9 5 5.0 2.7 26.7 80.1 -11.0 122 0.6
7250 20.0 68.0 185 10 5 4.5 2.5 26.3 79.4 -11.4 104 0.5
7000 20.3 68.5 180 10 5 4.6 2.5 25.9 78.7 -11.8 87 0.4
6750 20.6 69.1 175 9 5 1.2 0.7 25.5 77.8 -12.3 72 0.4
6500 20.5 68.9 170 9 5 -3.3 -1.8 24.6 76.3 -13.2 68 0.3
6250 20.2 68.4 160 8 4 -3.6 -2.0 23.6 74.5 -14.2 68 0.3
6000 20.0 68.0 150 8 4 -1.2 -0.6 22.7 72.8 -15.1 66 0.3
5750 19.7 67.5 135 6 3 -13.5 -7.4 21.6 70.9 -16.2 70 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 * * * * * *
07/29/2025 at 0900 MDT | 07/29/2025 at 1200 MDT
|
CAPE... +6.4 LI... +1.3 | CAPE... +71.3 LI... 0.0
CINH... -21.3 K Index... +18.2 | CINH... -39.4 K Index... +21.3
|
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 -61.6 -78.9 225 27 14 0.9 0.5 | -61.0 -77.8 225 24 12 1.6 0.9
45000 -59.1 -74.4 220 48 25 3.4 1.8 | -58.2 -72.8 220 45 23 2.3 1.3
40000 -53.4 -64.1 210 67 34 6.5 3.6 | -53.9 -65.0 210 60 31 6.9 3.8
38000 -49.5 -57.1 210 56 29 6.6 3.6 | -49.8 -57.6 210 55 28 6.9 3.8
36000 -45.1 -49.2 215 45 23 7.1 3.9 | -45.1 -49.2 215 48 25 7.3 4.0
34000 -40.5 -40.9 215 39 20 7.6 4.1 | -40.6 -41.1 215 41 21 7.6 4.2
32000 -36.0 -32.8 215 32 16 7.6 4.2 | -36.0 -32.8 215 35 18 7.6 4.2
30000 -31.7 -25.1 215 27 14 7.3 4.0 | -31.6 -24.9 220 29 15 7.3 4.0
29000 -29.5 -21.1 215 25 13 7.3 4.0 | -29.4 -20.9 220 26 13 7.3 4.0
28000 -27.3 -17.1 215 22 12 6.8 3.7 | -27.3 -17.1 220 23 12 7.1 3.9
27000 -25.3 -13.5 215 20 10 6.9 3.8 | -25.2 -13.4 220 22 11 7.1 3.9
26000 -23.3 -9.9 215 18 9 7.0 3.8 | -23.0 -9.4 225 20 10 7.1 3.9
25000 -21.2 -6.2 215 16 8 7.6 4.2 | -20.9 -5.6 225 18 9 7.1 3.9
24000 -18.8 -1.8 220 15 8 8.1 4.5 | -18.8 -1.8 225 16 8 7.2 3.9
23000 -16.4 2.5 230 14 7 8.2 4.5 | -16.7 1.9 230 14 7 7.2 4.0
22000 -13.4 7.9 235 13 7 7.3 4.0 | -14.0 6.8 230 12 6 7.8 4.3
21000 -11.3 11.7 230 11 6 7.4 4.1 | -11.8 10.8 235 12 6 7.8 4.3
20000 -9.1 15.6 230 10 5 7.5 4.1 | -9.5 14.9 235 11 6 7.9 4.3
19500 -8.0 17.6 225 9 5 7.5 4.1 | -8.4 16.9 240 11 6 7.9 4.3
19000 -6.9 19.6 220 8 4 7.6 4.1 | -7.3 18.9 240 11 6 7.9 4.3
18500 -5.9 21.4 220 8 4 7.6 4.2 | -6.1 21.0 240 10 5 8.0 4.4
18000 -4.7 23.5 220 7 4 8.4 4.6 | -4.9 23.2 240 10 5 9.0 4.9
17500 -3.4 25.9 220 6 3 8.4 4.6 | -3.6 25.5 240 9 5 8.9 4.9
17000 -2.2 28.0 220 6 3 8.8 4.8 | -2.3 27.9 240 9 5 9.0 4.9
16500 -0.8 30.6 225 5 3 8.9 4.9 | -0.9 30.4 240 9 5 9.0 5.0
16000 0.5 32.9 235 5 3 8.9 4.9 | 0.4 32.7 245 9 5 9.1 5.0
15500 1.8 35.2 240 5 3 8.8 4.9 | 1.8 35.2 245 9 4 9.2 5.1
15000 3.1 37.6 245 5 2 8.8 4.9 | 3.2 37.8 245 8 4 9.2 5.1
14500 4.5 40.1 250 5 3 8.9 4.9 | 4.6 40.3 245 8 4 9.4 5.2
14000 5.8 42.4 250 5 3 8.9 4.9 | 6.0 42.8 245 8 4 9.4 5.2
13500 7.1 44.8 255 5 3 8.9 4.9 | 7.4 45.3 245 8 4 9.1 5.0
13000 8.4 47.1 255 5 3 8.9 4.9 | 8.7 47.7 245 7 4 9.0 5.0
12500 9.7 49.5 255 6 3 8.8 4.8 | 10.1 50.2 245 7 4 9.3 5.1
12000 11.0 51.8 255 6 3 8.7 4.8 | 11.5 52.7 245 7 3 9.4 5.2
11500 12.3 54.1 250 6 3 8.7 4.8 | 12.9 55.2 245 6 3 9.3 5.1
11000 13.6 56.5 250 6 3 8.6 4.7 | 14.2 57.6 245 6 3 9.2 5.0
10500 14.9 58.8 245 6 3 7.0 3.9 | 15.6 60.1 240 5 3 8.1 4.4
10250 15.3 59.5 245 6 3 7.2 3.9 | 16.2 61.2 245 5 3 8.3 4.6
10000 16.0 60.8 240 6 3 9.3 5.1 | 16.9 62.4 245 5 3 9.9 5.4
9750 16.6 61.9 240 6 3 8.7 4.8 | 17.6 63.7 240 5 2 9.6 5.2
9500 17.3 63.1 235 6 3 8.7 4.8 | 18.3 64.9 240 5 2 9.5 5.2
9250 17.9 64.2 235 5 3 8.2 4.5 | 19.0 66.2 245 4 2 9.1 5.0
9000 18.5 65.3 230 5 3 7.2 3.9 | 19.7 67.5 245 4 2 9.0 4.9
8750 19.0 66.2 220 5 3 6.7 3.7 | 20.3 68.5 245 4 2 9.0 4.9
8500 19.5 67.1 215 6 3 7.2 3.9 | 21.0 69.8 245 4 2 8.3 4.5
8250 20.5 68.9 210 5 3 7.2 3.9 | 22.1 71.8 260 3 2 9.8 5.4
8000 21.1 70.0 200 5 3 6.7 3.7 | 22.9 73.2 255 4 2 12.1 6.6
7750 21.5 70.7 190 6 3 6.4 3.5 | 23.7 74.7 250 4 2 9.3 5.1
7500 22.0 71.6 190 5 3 6.0 3.3 | 24.3 75.7 260 3 2 7.7 4.2
7250 22.4 72.3 185 5 3 6.8 3.8 | 25.0 77.0 265 3 2 9.9 5.4
7000 23.0 73.4 180 5 3 7.9 4.3 | 25.8 78.4 260 3 2 12.5 6.8
6750 23.6 74.5 175 5 2 7.2 4.0 | 26.7 80.1 260 3 2 11.0 6.0
6500 24.1 75.4 170 4 2 7.4 4.1 | 27.5 81.5 265 3 2 10.5 5.7
6250 24.6 76.3 165 4 2 5.5 3.0 | 28.3 82.9 270 3 1 9.0 5.0
6000 25.0 77.0 140 4 2 9.0 4.9 | 29.0 84.2 260 3 2 16.0 8.8
5750 26.1 79.0 135 4 2 21.0 11.5 | 30.9 87.6 270 3 1 32.6 17.9
5500 27.3 81.1 130 3 2 -2.1 -1.2 | 32.7 90.9 285 3 1 1.8 1.0
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
07/29/2025 at 1500 MDT | 07/29/2025 at 1800 MDT
|
CAPE... +23.3 LI... +0.2 | CAPE... +50.9 LI... +0.6
CINH... -34.3 K Index... +20.1 | CINH... -42.2 K Index... +18.4
|
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 -61.0 -77.8 220 24 12 1.9 1.1 | -61.0 -77.8 220 24 13 1.3 0.7
45000 -58.1 -72.6 215 43 22 2.1 1.1 | -58.5 -73.3 215 43 22 2.4 1.3
40000 -54.1 -65.4 210 58 30 6.7 3.7 | -54.0 -65.2 200 56 29 6.7 3.7
38000 -50.0 -58.0 210 53 27 6.8 3.7 | -50.0 -58.0 205 51 26 6.7 3.7
36000 -45.4 -49.7 215 48 25 7.4 4.1 | -45.5 -49.9 210 47 24 7.3 4.0
34000 -40.7 -41.3 215 41 21 8.0 4.4 | -40.8 -41.4 210 41 21 7.8 4.3
32000 -35.9 -32.6 210 34 17 8.1 4.5 | -36.1 -33.0 215 36 19 7.9 4.4
30000 -31.4 -24.5 215 28 14 7.5 4.1 | -31.7 -25.1 220 30 16 7.3 4.0
29000 -29.1 -20.4 215 25 13 7.5 4.1 | -29.6 -21.3 225 28 14 7.3 4.0
28000 -27.0 -16.6 215 22 11 6.8 3.7 | -27.4 -17.3 230 26 13 7.4 4.0
27000 -24.9 -12.8 220 20 11 6.9 3.8 | -25.2 -13.4 235 24 13 7.4 4.0
26000 -22.9 -9.2 225 19 10 6.9 3.8 | -23.0 -9.4 235 23 12 7.4 4.0
25000 -20.8 -5.4 230 18 9 7.0 3.9 | -20.8 -5.4 240 22 11 7.6 4.2
24000 -18.7 -1.7 235 17 9 7.2 3.9 | -18.5 -1.3 240 20 10 7.9 4.4
23000 -16.0 3.2 235 15 8 7.2 4.0 | -16.1 3.0 245 19 10 7.9 4.4
22000 -13.9 7.0 240 14 7 8.1 4.4 | -13.1 8.4 250 17 9 8.3 4.6
21000 -11.5 11.3 240 13 7 8.0 4.4 | -10.7 12.7 245 16 8 8.4 4.6
20000 -9.2 15.4 240 12 6 8.1 4.4 | -8.2 17.2 245 15 8 8.4 4.6
19500 -8.0 17.6 245 11 6 8.4 4.6 | -7.0 19.4 245 14 7 8.5 4.6
19000 -6.8 19.8 245 11 6 8.5 4.7 | -5.8 21.6 245 14 7 8.5 4.7
18500 -5.5 22.1 250 11 5 8.6 4.7 | -4.6 23.7 245 13 7 8.5 4.7
18000 -4.2 24.4 255 10 5 9.1 5.0 | -3.3 26.1 245 13 7 8.9 4.9
17500 -2.9 26.8 255 10 5 9.0 5.0 | -2.0 28.4 250 13 6 8.9 4.9
17000 -1.5 29.3 260 10 5 9.2 5.1 | -0.7 30.7 250 12 6 9.0 5.0
16500 -0.2 31.6 260 10 5 9.3 5.1 | 0.7 33.3 255 12 6 9.1 5.0
16000 1.2 34.2 265 9 5 9.3 5.1 | 2.0 35.6 255 12 6 9.2 5.0
15500 2.6 36.7 265 9 5 9.3 5.1 | 3.4 38.1 255 12 6 9.3 5.1
15000 4.0 39.2 265 9 5 9.3 5.1 | 4.7 40.5 260 12 6 9.3 5.1
14500 5.3 41.5 270 9 5 9.2 5.1 | 6.1 43.0 260 12 6 9.4 5.2
14000 6.7 44.1 270 9 5 9.2 5.0 | 7.5 45.5 260 12 6 9.4 5.2
13500 8.1 46.6 270 9 5 9.4 5.1 | 8.9 48.0 265 12 6 9.5 5.2
13000 9.5 49.1 270 9 5 9.4 5.1 | 10.3 50.5 265 11 6 9.5 5.2
12500 10.9 51.6 270 9 5 9.4 5.2 | 11.7 53.1 265 11 6 9.5 5.2
12000 12.3 54.1 270 9 5 9.4 5.2 | 13.2 55.8 270 11 6 9.5 5.2
11500 13.7 56.7 270 9 5 9.4 5.2 | 14.6 58.3 270 11 6 9.4 5.2
11000 15.1 59.2 265 9 5 9.3 5.1 | 16.0 60.8 270 11 6 9.2 5.1
10500 16.6 61.9 265 9 5 7.2 3.9 | 17.4 63.3 270 11 6 7.2 4.0
10250 17.0 62.6 265 9 5 7.6 4.2 | 17.8 64.0 270 11 6 7.8 4.3
10000 17.8 64.0 265 9 5 10.8 5.9 | 18.6 65.5 270 11 6 10.9 6.0
9750 18.5 65.3 265 9 5 10.2 5.6 | 19.4 66.9 270 11 6 10.3 5.7
9500 19.3 66.7 260 9 5 9.6 5.3 | 20.1 68.2 270 11 5 9.7 5.3
9250 19.9 67.8 265 9 5 9.0 5.0 | 20.8 69.4 275 11 6 8.9 4.9
9000 20.6 69.1 265 9 5 9.5 5.2 | 21.5 70.7 275 11 5 9.5 5.2
8750 21.3 70.3 260 9 5 9.7 5.3 | 22.2 72.0 275 10 5 9.7 5.3
8500 22.1 71.8 260 9 4 9.0 5.0 | 22.9 73.2 275 10 5 9.0 4.9
8250 23.3 73.9 265 9 5 9.7 5.3 | 24.1 75.4 275 11 5 9.6 5.2
8000 24.1 75.4 260 9 5 11.0 6.0 | 24.9 76.8 275 10 5 11.6 6.3
7750 24.9 76.8 255 8 4 9.1 5.0 | 25.8 78.4 275 10 5 9.7 5.3
7500 25.5 77.9 260 9 4 7.6 4.2 | 26.4 79.5 275 10 5 8.0 4.4
7250 26.1 79.0 260 9 5 9.5 5.2 | 27.0 80.6 280 11 5 9.5 5.2
7000 26.9 80.4 255 9 4 12.0 6.6 | 27.8 82.0 280 10 5 11.9 6.5
6750 27.8 82.0 250 8 4 10.7 5.9 | 28.7 83.7 275 10 5 10.9 6.0
6500 28.5 83.3 255 8 4 10.0 5.5 | 29.5 85.1 280 10 5 10.0 5.5
6250 29.2 84.6 255 8 4 8.5 4.7 | 30.2 86.4 280 10 5 9.2 5.1
6000 29.9 85.8 255 8 4 13.3 7.3 | 30.9 87.6 280 10 5 11.5 6.3
5750 31.4 88.5 255 7 4 27.9 15.3 | 32.1 89.8 280 9 4 20.4 11.2
5500 33.2 91.8 260 7 4 6.7 3.7 | 33.6 92.5 285 9 4 16.9 9.3
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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