Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
196
UXUS97 KGJT 241306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Tuesday, June 24, 2025
This forecast is for Tuesday, June 24, 2025:
If the trigger temperature of 84.4 F/29.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1591 ft/min (8.1 m/s)
Maximum height of thermals.................. 20917 ft MSL (16078 ft AGL)
Forecast maximum temperature................... 92.0 F/33.8 C
Time of trigger temperature.................... 1045 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................. 13115 ft MSL (8275 ft AGL)
Thermal soaring outlook for Wednesday 06/25.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:49:19 / 20:44:07 MDT
Total possible sunshine........... 14 hr 54 min 48 sec (894 min 48 sec)
Altitude of sun at 13:16:43 MDT... 73.88 degrees
Upper air data from rawinsonde observation taken on 06/24/2025 at 0600 MDT
Freezing level.................. 14902 ft MSL (10063 ft AGL)
Convective condensation level... 18920 ft MSL (14081 ft AGL)
Lifted condensation level....... 19635 ft MSL (14796 ft AGL)
Lifted index.................... -1.9
K index......................... +14.3
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 -65.2 -85.4 215 63 32 4.9 2.7 86.7 188.0 30.8 M M
45000 -59.7 -75.5 215 93 48 6.3 3.4 70.1 158.2 22.9 M M
40000 -50.3 -58.5 215 96 49 7.9 4.4 61.9 143.4 19.0 M M
38000 -45.7 -50.3 220 87 45 5.4 2.9 60.1 140.1 18.3 M M
36000 -42.6 -44.7 215 92 47 6.7 3.7 56.1 133.0 16.0 M M
34000 -39.5 -39.1 220 87 45 5.2 2.9 52.3 126.1 13.6 M M
32000 -36.7 -34.1 220 80 41 2.3 1.3 47.1 116.7 10.1 M M
30000 -31.7 -25.1 215 74 38 8.5 4.7 45.9 114.7 9.5 M M
29000 -29.5 -21.1 220 69 36 5.8 3.2 44.9 112.9 8.9 M M
28000 -27.6 -17.7 215 63 32 5.8 3.2 43.7 110.7 8.0 M M
27000 -26.6 -15.9 220 62 32 6.9 3.8 41.2 106.1 6.1 M M
26000 -24.3 -11.7 220 59 30 7.7 4.2 40.4 104.7 5.6 M M
25000 -22.0 -7.6 220 56 29 6.3 3.5 39.6 103.2 5.0 M M
24000 -20.9 -5.6 215 51 26 -3.9 -2.2 37.4 99.3 3.3 M M
23000 -20.0 -4.0 210 53 28 6.2 3.4 35.0 95.0 1.3 M M
22000 -18.1 -0.6 210 57 29 8.8 4.8 33.9 93.1 0.3 M M
21000 -15.3 4.5 205 55 28 7.4 4.1 33.9 93.0 0.2 M M
20000 -13.6 7.5 205 53 27 7.8 4.3 32.5 90.5 -1.1 1524 7.7
19500 -12.2 10.0 210 51 26 9.8 5.4 32.5 90.5 -1.1 1466 7.4
19000 -10.8 12.6 205 47 24 7.9 4.4 32.4 90.4 -1.1 1409 7.2
18500 -9.7 14.5 200 43 22 6.2 3.4 31.9 89.4 -1.6 1363 6.9
18000 -8.6 16.5 195 39 20 8.4 4.6 31.5 88.7 -1.9 1315 6.7
17500 -7.5 18.5 195 37 19 7.6 4.1 31.1 88.0 -2.3 1267 6.4
17000 -5.7 21.7 195 37 19 9.7 5.3 30.8 87.4 -2.7 1191 6.1
16500 -4.3 24.3 190 35 18 9.5 5.2 30.8 87.4 -2.7 1134 5.8
16000 -2.9 26.8 190 30 16 9.5 5.2 30.8 87.4 -2.7 1077 5.5
15500 -1.5 29.3 195 31 16 9.5 5.2 30.7 87.3 -2.8 1019 5.2
15000 -0.0 32.0 200 26 13 9.5 5.2 30.7 87.3 -2.8 962 4.9
14500 1.4 34.5 200 26 13 9.5 5.2 30.7 87.2 -2.8 905 4.6
14000 2.8 37.0 205 27 14 9.5 5.2 30.6 87.1 -2.9 848 4.3
13500 4.2 39.6 205 28 14 9.5 5.2 30.6 87.1 -3.0 791 4.0
13000 5.6 42.1 205 29 15 9.5 5.2 30.5 87.0 -3.0 733 3.7
12500 7.0 44.6 215 27 14 9.5 5.2 30.5 86.8 -3.1 676 3.4
12000 8.4 47.1 215 25 13 9.5 5.2 30.4 86.7 -3.2 619 3.1
11500 9.9 49.8 215 25 13 9.5 5.2 30.3 86.5 -3.3 562 2.9
11000 11.3 52.3 215 25 13 9.5 5.2 30.2 86.4 -3.4 504 2.6
10500 12.7 54.9 220 25 13 9.4 5.2 30.1 86.2 -3.5 447 2.3
10250 13.4 56.1 220 25 13 9.2 5.1 30.1 86.1 -3.5 419 2.1
10000 14.1 57.4 220 25 13 9.1 5.0 30.0 86.0 -3.6 391 2.0
9750 14.7 58.5 215 24 12 9.1 5.0 30.0 85.9 -3.7 364 1.8
9500 15.4 59.7 215 23 12 9.1 5.0 29.9 85.8 -3.7 336 1.7
9250 16.1 61.0 210 22 11 9.1 5.0 29.9 85.7 -3.8 308 1.6
9000 16.7 62.1 205 21 11 8.0 4.4 29.8 85.6 -3.9 282 1.4
8750 17.3 63.1 200 21 11 7.2 4.0 29.6 85.3 -4.1 259 1.3
8500 17.8 64.0 195 20 10 7.5 4.1 29.4 84.9 -4.3 236 1.2
8250 18.3 64.9 190 20 10 6.2 3.4 29.2 84.6 -4.6 214 1.1
8000 18.7 65.7 185 20 10 5.3 2.9 28.9 84.0 -4.9 195 1.0
7750 19.1 66.4 175 20 10 5.5 3.0 28.5 83.4 -5.3 175 0.9
7500 19.4 66.9 165 22 11 5.8 3.2 28.2 82.8 -5.6 156 0.8
7250 19.8 67.6 160 23 12 4.4 2.4 27.9 82.2 -6.0 137 0.7
7000 20.0 68.0 150 25 13 -0.4 -0.2 27.3 81.2 -6.6 125 0.6
6750 20.0 68.0 150 28 14 2.2 1.2 26.5 79.8 -7.3 118 0.6
6500 20.2 68.4 145 28 14 -2.1 -1.1 26.0 78.8 -7.9 104 0.5
6250 19.8 67.6 135 25 13 -0.3 -0.2 24.9 76.8 -9.0 108 0.5
6000 20.3 68.5 130 23 12 8.2 4.5 24.6 76.3 -9.3 87 0.4
5750 20.8 69.4 120 22 11 7.1 3.9 24.4 75.9 -9.5 65 0.3
5500 21.3 70.3 115 21 11 4.7 2.6 24.2 75.6 -9.8 43 0.2
5250 21.1 70.0 120 20 10 -10.6 -5.8 23.3 74.0 -10.7 40 0.2
5000 19.6 67.3 120 24 12 -29.7 -16.3 21.0 69.8 -13.0 79 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/24/2025 at 0900 MDT | 06/24/2025 at 1200 MDT
|
CAPE... 0.0 LI... +2.1 | CAPE... +0.7 LI... +1.8
CINH... -1.1 K Index... +17.8 | CINH... -0.2 K Index... +18.8
|
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 -63.4 -82.1 215 58 30 0.7 0.4 | -63.9 -83.0 215 62 32 0.9 0.5
45000 -59.8 -75.6 215 88 45 6.5 3.6 | -60.2 -76.4 215 89 46 6.3 3.5
40000 -50.2 -58.4 210 97 50 5.8 3.2 | -50.7 -59.3 210 99 51 6.3 3.4
38000 -46.7 -52.1 210 93 48 5.8 3.2 | -47.0 -52.6 210 94 49 6.3 3.4
36000 -43.3 -45.9 210 89 46 5.8 3.2 | -42.8 -45.0 210 90 46 6.3 3.5
34000 -39.4 -38.9 215 84 43 5.8 3.2 | -39.2 -38.6 210 85 44 5.9 3.2
32000 -35.9 -32.6 215 79 41 5.8 3.2 | -35.7 -32.3 210 79 41 5.9 3.2
30000 -32.1 -25.8 215 72 37 6.4 3.5 | -31.9 -25.4 210 72 37 6.5 3.5
29000 -30.2 -22.4 215 68 35 6.4 3.5 | -29.9 -21.8 210 68 35 6.5 3.5
28000 -28.3 -18.9 215 64 33 6.5 3.5 | -28.0 -18.4 210 64 33 6.6 3.6
27000 -26.3 -15.3 215 60 31 6.6 3.6 | -25.9 -14.6 210 61 31 7.1 3.9
26000 -24.3 -11.7 215 55 28 6.6 3.6 | -23.8 -10.8 210 57 29 7.1 3.9
25000 -22.3 -8.1 215 51 26 6.7 3.6 | -21.6 -6.9 210 53 27 7.1 3.9
24000 -20.4 -4.7 215 47 24 6.4 3.5 | -19.6 -3.3 210 50 26 6.8 3.7
23000 -18.5 -1.3 215 45 23 6.4 3.5 | -17.5 0.5 210 46 24 6.8 3.7
22000 -16.6 2.1 210 42 22 6.4 3.5 | -15.0 5.0 210 42 22 6.3 3.5
21000 -14.4 6.1 210 42 22 6.0 3.3 | -13.3 8.1 210 42 21 5.7 3.1
20000 -12.6 9.3 205 42 22 6.1 3.3 | -11.7 10.9 205 41 21 5.7 3.2
19500 -11.8 10.8 205 42 22 6.0 3.3 | -10.8 12.6 205 41 21 5.8 3.2
19000 -10.8 12.6 205 43 22 8.4 4.6 | -10.0 14.0 205 41 21 6.2 3.4
18500 -9.6 14.7 205 43 22 8.2 4.5 | -9.1 15.6 205 41 21 6.3 3.4
18000 -8.4 16.9 205 43 22 8.3 4.6 | -8.3 17.1 205 41 21 6.8 3.7
17500 -7.2 19.0 205 43 22 8.4 4.6 | -7.2 19.0 205 40 21 7.2 3.9
17000 -6.1 21.0 205 43 22 8.4 4.6 | -6.2 20.8 205 40 20 7.3 4.0
16500 -4.9 23.2 205 42 21 8.3 4.5 | -5.1 22.8 205 39 20 7.9 4.3
16000 -3.7 25.3 205 41 21 8.3 4.6 | -4.0 24.8 205 37 19 7.8 4.3
15500 -2.5 27.5 210 40 20 8.0 4.4 | -2.8 27.0 205 35 18 8.4 4.6
15000 -1.3 29.7 210 39 20 7.9 4.3 | -1.6 29.1 205 34 17 8.5 4.7
14500 -0.1 31.8 210 38 19 8.0 4.4 | -0.3 31.5 205 32 16 8.7 4.8
14000 1.1 34.0 210 36 19 8.1 4.4 | 1.0 33.8 205 29 15 8.9 4.9
13500 2.4 36.3 210 35 18 8.1 4.4 | 2.4 36.3 210 27 14 9.0 4.9
13000 3.6 38.5 210 33 17 8.2 4.5 | 3.7 38.7 210 26 13 9.1 5.0
12500 4.8 40.6 210 31 16 8.2 4.5 | 5.1 41.2 210 24 12 9.1 5.0
12000 6.1 43.0 210 29 15 8.4 4.6 | 6.5 43.7 210 22 12 9.1 5.0
11500 7.4 45.3 205 27 14 8.4 4.6 | 7.8 46.0 210 21 11 9.1 5.0
11000 8.7 47.7 205 25 13 8.8 4.8 | 9.2 48.6 210 20 10 9.0 4.9
10500 10.1 50.2 205 23 12 7.2 4.0 | 10.6 51.1 210 19 10 7.3 4.0
10250 10.5 50.9 210 22 11 7.6 4.2 | 11.0 51.8 210 17 9 7.8 4.3
10000 11.2 52.2 210 22 11 9.9 5.5 | 11.8 53.2 215 17 9 10.4 5.7
9750 11.9 53.4 210 21 11 9.3 5.1 | 12.5 54.5 215 17 9 9.7 5.3
9500 12.7 54.9 210 21 11 9.5 5.2 | 13.3 55.9 215 17 9 10.0 5.5
9250 13.4 56.1 210 20 10 9.5 5.2 | 14.0 57.2 220 16 8 10.2 5.6
9000 14.0 57.2 210 19 10 8.6 4.7 | 14.8 58.6 220 15 8 9.7 5.3
8750 14.6 58.3 210 19 10 8.0 4.4 | 15.5 59.9 220 15 8 9.3 5.1
8500 15.3 59.5 210 19 10 8.1 4.5 | 16.2 61.2 220 15 8 9.4 5.2
8250 15.8 60.4 210 18 9 7.8 4.3 | 17.6 63.7 225 14 7 9.9 5.4
8000 17.0 62.6 205 17 9 8.5 4.7 | 18.4 65.1 225 14 7 10.7 5.9
7750 17.6 63.7 205 16 8 7.7 4.2 | 19.1 66.4 225 14 7 10.0 5.5
7500 18.1 64.6 200 15 8 6.3 3.5 | 19.8 67.6 225 13 7 8.8 4.8
7250 18.6 65.5 200 14 7 6.5 3.6 | 20.5 68.9 225 13 7 9.2 5.1
7000 19.1 66.4 195 14 7 8.4 4.6 | 21.3 70.3 230 13 7 11.3 6.2
6750 19.7 67.5 195 13 7 9.1 5.0 | 22.1 71.8 230 13 6 11.5 6.3
6500 20.4 68.7 190 12 6 9.0 4.9 | 23.0 73.4 230 12 6 11.2 6.1
6250 21.0 69.8 190 11 6 8.4 4.6 | 23.8 74.8 230 12 6 10.0 5.5
6000 21.7 71.1 190 10 5 9.9 5.5 | 24.6 76.3 230 11 6 12.9 7.1
5750 22.6 72.7 190 9 5 17.4 9.5 | 26.0 78.8 235 11 5 27.0 14.8
5500 24.1 75.4 185 8 4 22.0 12.1 | 28.5 83.3 235 10 5 37.2 20.4
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
06/24/2025 at 1500 MDT | 06/24/2025 at 1800 MDT
|
CAPE... +19.5 LI... +0.1 | CAPE... +26.1 LI... -0.2
CINH... -1.6 K Index... +18.9 | CINH... -7.4 K Index... +20.2
|
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 -63.8 -82.8 215 62 32 1.0 0.5 | -63.3 -81.9 220 57 29 1.1 0.6
45000 -60.1 -76.2 215 86 45 6.0 3.3 | -59.7 -75.5 215 84 43 5.5 3.0
40000 -51.0 -59.8 205 96 49 6.9 3.8 | -51.3 -60.3 205 96 49 6.8 3.7
38000 -46.9 -52.4 205 93 48 6.9 3.8 | -47.3 -53.1 205 93 48 6.7 3.7
36000 -42.2 -44.0 205 90 46 7.1 3.9 | -42.7 -44.9 205 89 46 6.9 3.8
34000 -38.8 -37.8 210 84 43 5.4 3.0 | -39.2 -38.6 205 83 43 5.8 3.2
32000 -35.5 -31.9 210 78 40 5.4 3.0 | -35.7 -32.3 205 76 39 5.7 3.1
30000 -31.7 -25.1 210 71 37 6.7 3.7 | -31.8 -25.2 210 69 36 6.9 3.8
29000 -29.7 -21.5 210 67 35 6.7 3.7 | -29.7 -21.5 210 65 34 6.9 3.8
28000 -27.7 -17.9 210 63 33 6.9 3.8 | -27.6 -17.7 210 62 32 7.1 3.9
27000 -25.5 -13.9 210 60 31 7.4 4.1 | -25.4 -13.7 210 58 30 7.6 4.2
26000 -23.3 -9.9 210 56 29 7.4 4.1 | -23.1 -9.6 210 54 28 7.6 4.2
25000 -21.1 -6.0 210 53 27 7.5 4.1 | -20.8 -5.4 210 51 26 7.7 4.2
24000 -19.1 -2.4 205 49 25 6.3 3.4 | -18.8 -1.8 210 47 24 6.1 3.4
23000 -17.2 1.0 205 46 23 6.3 3.4 | -17.0 1.4 210 43 22 6.2 3.4
22000 -14.9 5.2 205 41 21 5.8 3.2 | -14.8 5.4 210 38 20 5.9 3.2
21000 -13.4 7.9 205 38 19 5.2 2.9 | -13.2 8.2 210 33 17 5.5 3.0
20000 -11.9 10.6 205 35 18 5.4 3.0 | -11.6 11.1 205 29 15 5.7 3.1
19500 -11.1 12.0 205 34 17 5.4 3.0 | -10.8 12.6 205 26 14 5.7 3.1
19000 -10.2 13.6 205 32 17 7.9 4.3 | -9.8 14.4 205 25 13 8.4 4.6
18500 -9.1 15.6 205 31 16 7.8 4.3 | -8.7 16.3 205 24 12 8.2 4.5
18000 -8.0 17.6 205 30 15 8.3 4.6 | -7.5 18.5 205 23 12 8.6 4.7
17500 -6.7 19.9 205 29 15 8.7 4.8 | -6.2 20.8 205 22 11 8.9 4.9
17000 -5.4 22.3 205 28 14 8.7 4.8 | -4.8 23.4 205 22 11 9.0 4.9
16500 -4.1 24.6 205 27 14 9.3 5.1 | -3.5 25.7 205 21 11 9.3 5.1
16000 -2.7 27.1 205 26 13 9.3 5.1 | -2.1 28.2 205 21 11 9.2 5.1
15500 -1.4 29.5 205 25 13 9.2 5.0 | -0.7 30.7 205 20 10 9.4 5.1
15000 0.0 32.0 205 24 13 9.2 5.0 | 0.7 33.3 205 20 10 9.4 5.1
14500 1.4 34.5 205 24 12 9.2 5.1 | 2.1 35.8 210 19 10 9.4 5.1
14000 2.8 37.0 205 23 12 9.3 5.1 | 3.5 38.3 210 19 10 9.3 5.1
13500 4.2 39.6 205 22 11 9.3 5.1 | 4.9 40.8 210 18 9 9.3 5.1
13000 5.5 41.9 210 21 11 9.1 5.0 | 6.3 43.3 215 18 9 9.3 5.1
12500 6.9 44.4 210 21 11 9.1 5.0 | 7.6 45.7 215 17 9 9.3 5.1
12000 8.2 46.8 210 20 10 9.0 4.9 | 9.0 48.2 215 17 9 9.2 5.1
11500 9.6 49.3 210 19 10 9.1 5.0 | 10.4 50.7 220 16 8 9.4 5.2
11000 10.9 51.6 215 18 9 8.4 4.6 | 11.7 53.1 220 16 8 7.8 4.3
10500 12.1 53.8 220 16 8 9.7 5.3 | 12.8 55.0 225 15 8 10.9 6.0
10250 12.9 55.2 220 16 8 10.4 5.7 | 13.8 56.8 225 15 8 12.0 6.6
10000 13.6 56.5 220 16 8 9.1 5.0 | 14.5 58.1 230 15 8 8.5 4.7
9750 14.3 57.7 225 16 8 9.4 5.2 | 15.2 59.4 230 15 8 9.2 5.1
9500 15.0 59.0 225 16 8 9.4 5.1 | 15.9 60.6 235 14 7 9.3 5.1
9250 15.8 60.4 230 15 8 10.2 5.6 | 16.5 61.7 235 14 7 7.8 4.3
9000 16.5 61.7 230 14 7 10.0 5.5 | 17.1 62.8 235 13 7 8.2 4.5
8750 17.2 63.0 230 15 8 9.3 5.1 | 17.8 64.0 240 13 7 9.9 5.4
8500 18.7 65.7 230 15 8 9.3 5.1 | 19.2 66.6 240 14 7 8.8 4.8
8250 19.4 66.9 235 14 7 9.9 5.4 | 19.9 67.8 245 13 7 9.3 5.1
8000 20.1 68.2 235 14 7 10.6 5.8 | 20.6 69.1 245 13 7 10.4 5.7
7750 20.9 69.6 235 14 7 10.1 5.6 | 21.4 70.5 245 13 7 10.0 5.5
7500 21.6 70.9 235 14 7 8.9 4.9 | 22.1 71.8 245 13 7 9.1 5.0
7250 22.3 72.1 235 14 7 9.2 5.0 | 22.8 73.0 245 13 7 9.1 5.0
7000 23.0 73.4 240 14 7 11.1 6.1 | 23.5 74.3 250 13 7 10.6 5.8
6750 23.9 75.0 240 14 7 11.5 6.3 | 24.3 75.7 250 13 7 10.9 6.0
6500 24.7 76.5 240 13 7 11.2 6.2 | 25.1 77.2 250 13 6 10.5 5.8
6250 25.6 78.1 240 13 7 10.8 5.9 | 25.9 78.6 250 12 6 10.6 5.8
6000 26.4 79.5 240 13 6 10.9 6.0 | 26.7 80.1 250 12 6 8.8 4.8
5750 27.4 81.3 240 12 6 21.6 11.9 | 27.3 81.1 250 11 6 12.5 6.9
5500 30.3 86.5 245 11 6 63.6 34.9 | 29.4 84.9 255 10 5 53.3 29.2
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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