Grand Junction Soaring Forecast

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976
UXUS97 KGJT 201306
SRGGJT

Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Tuesday, May 20, 2025

This forecast is for Tuesday, May 20, 2025:

If the trigger temperature of 63.7 F/17.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1090 ft/min (5.5 m/s)
Maximum height of thermals.................. 17524 ft MSL (11916 ft AGL)

Forecast maximum temperature................... 73.0 F/23.2 C
Time of trigger temperature.................... 1200 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................. 14965 ft MSL (9358 ft AGL)
Thermal soaring outlook for Wednesday 05/21.... Excellent

Wave Soaring Index............................. Not available

Remarks...

Sunrise/Sunset.................... 05:56:28 / 20:24:59 MDT
Total possible sunshine........... 14 hr 28 min 31 sec (868 min 31 sec)
Altitude of sun at 13:10:43 MDT... 70.90 degrees

Upper air data from rawinsonde observation taken on 05/20/2025 at 0600 MDT

Freezing level.................. 11820 ft MSL (6212 ft AGL)
Convective condensation level... 16526 ft MSL (10918 ft AGL)
Lifted condensation level....... 17314 ft MSL (11707 ft AGL)
Lifted index.................... -0.2
K index......................... +18.1

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 -58.2 -72.8 270 37 19 2.9 1.6 M M M M M
45000 -54.4 -65.9 280 57 29 -2.9 -1.6 M M M M M
40000 -58.7 -73.7 275 79 41 -2.8 -1.5 M M M M M
38000 -56.9 -70.4 280 81 42 5.8 3.2 M M M M M
36000 -53.4 -64.1 285 81 41 5.8 3.2 M M M M M
34000 -49.6 -57.3 285 80 41 7.3 4.0 M M M M M
32000 -44.7 -48.5 285 78 40 7.3 4.0 M M M M M
30000 -40.4 -40.7 285 76 39 7.0 3.9 34.5 94.1 8.9 M M
29000 -38.3 -36.9 290 74 38 7.0 3.9 33.4 92.1 8.1 M M
28000 -36.2 -33.2 290 72 37 7.0 3.9 32.4 90.3 7.4 M M
27000 -34.1 -29.4 290 69 36 6.7 3.7 31.4 88.5 6.7 M M
26000 -32.1 -25.8 290 65 34 6.7 3.7 30.1 86.2 5.8 M M
25000 -30.1 -22.2 290 61 32 6.7 3.7 29.0 84.3 5.0 M M
24000 -28.0 -18.4 290 58 30 8.6 4.7 28.1 82.6 4.3 M M
23000 -25.4 -13.7 290 58 30 8.7 4.8 27.7 81.8 4.0 M M
22000 -22.8 -9.0 290 57 30 8.7 4.8 27.3 81.2 3.7 M M
21000 -20.3 -4.5 290 56 29 6.9 3.8 26.8 80.2 3.3 M M
20000 -18.2 -0.8 290 52 27 7.1 3.9 25.8 78.4 2.5 M M
19500 -17.2 1.0 290 51 26 7.1 3.9 25.3 77.6 2.1 M M
19000 -15.6 3.9 290 48 25 6.7 3.7 24.7 76.5 1.6 M M
18500 -14.7 5.5 290 47 24 5.9 3.3 24.1 75.3 1.0 M M
18000 -13.8 7.2 290 45 23 6.0 3.3 23.4 74.1 0.5 M M
17500 -13.0 8.6 285 44 23 4.9 2.7 22.7 72.8 -0.2 1081 5.5
17000 -12.3 9.9 285 43 22 5.1 2.8 21.9 71.4 -0.9 1045 5.3
16500 -11.5 11.3 285 42 22 6.0 3.3 21.1 70.0 -1.7 1009 5.1
16000 -10.6 12.9 285 40 20 6.9 3.8 20.6 69.1 -2.2 965 4.9
15500 -9.6 14.7 280 37 19 7.3 4.0 20.1 68.2 -2.7 921 4.7
15000 -8.4 16.9 280 34 18 8.7 4.7 19.9 67.7 -3.0 872 4.4
14500 -7.2 19.0 280 32 16 8.6 4.7 19.7 67.4 -3.3 820 4.2
14000 -5.9 21.4 275 29 15 9.4 5.1 19.6 67.2 -3.4 766 3.9
13500 -4.6 23.7 275 28 14 9.3 5.1 19.5 67.1 -3.6 711 3.6
13000 -3.2 26.2 275 26 14 9.1 5.0 19.4 66.9 -3.7 655 3.3
12500 -1.8 28.8 270 25 13 9.2 5.0 19.3 66.7 -3.8 600 3.0
12000 -0.5 31.1 270 24 12 8.9 4.9 19.2 66.5 -3.9 544 2.8
11500 0.8 33.4 270 23 12 9.0 4.9 19.0 66.3 -4.1 490 2.5
11000 2.1 35.8 270 21 11 7.8 4.3 18.8 65.9 -4.3 437 2.2
10500 3.3 37.9 270 19 10 8.8 4.9 18.5 65.3 -4.6 388 2.0
10250 4.0 39.2 270 18 9 9.9 5.4 18.5 65.3 -4.6 358 1.8
10000 4.7 40.5 270 17 9 8.1 4.4 18.4 65.2 -4.7 331 1.7
9750 5.2 41.4 270 16 8 7.7 4.2 18.3 64.9 -4.9 306 1.6
9500 5.8 42.4 270 15 8 7.6 4.1 18.1 64.6 -5.0 281 1.4
9250 6.4 43.5 270 14 7 8.5 4.7 18.0 64.4 -5.2 256 1.3
9000 7.1 44.8 270 12 6 8.3 4.6 17.9 64.2 -5.2 229 1.2
8750 7.6 45.7 270 11 6 7.1 3.9 17.7 63.9 -5.4 205 1.0
8500 8.2 46.8 270 10 5 7.5 4.1 17.5 63.6 -5.6 181 0.9
8250 8.7 47.7 270 9 4 5.7 3.1 17.3 63.2 -5.8 158 0.8
8000 9.1 48.4 270 7 4 5.3 2.9 17.0 62.5 -6.2 139 0.7
7750 9.5 49.1 265 6 3 6.2 3.4 16.7 62.0 -6.5 118 0.6
7500 10.0 50.0 260 5 2 5.8 3.2 16.4 61.5 -6.8 97 0.5
7250 10.4 50.7 240 3 2 5.4 3.0 16.1 60.9 -7.1 77 0.4
7000 10.8 51.4 210 3 2 4.8 2.7 15.7 60.3 -7.5 58 0.3
6750 11.2 52.2 190 3 2 5.7 3.1 15.4 59.6 -7.8 40 0.2
6500 11.6 52.9 175 4 2 2.3 1.3 15.0 59.0 -8.2 21 0.1
6250 11.5 52.7 160 5 2 -3.1 -1.7 14.2 57.5 -9.0 16 0.1
6000 11.4 52.5 150 6 3 4.4 2.4 13.4 56.1 -9.9 11 0.1
5750 11.8 53.2 140 6 3 -2.3 -1.3 13.0 55.4 -10.2 M M
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 * * * * * *

05/20/2025 at 0900 MDT | 05/20/2025 at 1200 MDT
|
CAPE... 0.0 LI... +7.5 | CAPE... 0.0 LI... +6.0
CINH... -0.3 K Index... +2.2 | CINH... -0.0 K Index... +4.8
|
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 -57.7 -71.9 275 31 16 2.2 1.2 | -57.8 -72.0 265 32 16 1.8 1.0
45000 -54.6 -66.3 280 45 23 1.1 0.6 | -55.1 -67.2 275 48 25 1.9 1.0
40000 -53.0 -63.4 280 71 37 1.1 0.6 | -52.4 -62.3 275 72 37 1.9 1.0
38000 -51.4 -60.5 280 77 40 3.5 1.9 | -51.5 -60.7 280 74 38 1.1 0.6
36000 -49.1 -56.4 285 81 42 3.5 1.9 | -50.8 -59.4 280 71 37 1.1 0.6
34000 -46.9 -52.4 285 81 41 3.8 2.1 | -49.0 -56.2 285 69 35 6.0 3.3
32000 -44.6 -48.3 290 73 38 3.8 2.1 | -45.5 -49.9 290 66 34 5.9 3.3
30000 -41.7 -43.1 295 67 34 6.8 3.7 | -41.7 -43.1 290 63 32 7.0 3.9
29000 -39.7 -39.5 295 65 33 6.8 3.7 | -39.6 -39.3 290 61 31 7.0 3.9
28000 -37.7 -35.9 295 62 32 6.8 3.7 | -37.5 -35.5 290 59 30 7.0 3.9
27000 -35.6 -32.1 295 60 31 8.0 4.4 | -35.3 -31.5 290 57 29 7.9 4.3
26000 -33.1 -27.6 295 58 30 8.2 4.5 | -33.0 -27.4 290 55 28 7.9 4.3
25000 -30.7 -23.3 295 56 29 8.2 4.5 | -30.6 -23.1 290 54 28 7.9 4.3
24000 -28.2 -18.8 295 54 28 8.3 4.6 | -28.2 -18.8 290 52 27 8.2 4.5
23000 -25.7 -14.3 295 53 27 8.4 4.6 | -25.7 -14.3 290 50 26 8.5 4.7
22000 -22.5 -8.5 300 52 27 8.4 4.6 | -22.5 -8.5 290 49 25 8.5 4.6
21000 -20.1 -4.2 300 50 26 7.3 4.0 | -20.1 -4.2 295 47 24 7.3 4.0
20000 -17.9 -0.2 300 48 25 7.3 4.0 | -17.9 -0.2 295 46 24 7.3 4.0
19500 -16.8 1.8 300 47 24 7.4 4.0 | -16.8 1.8 295 45 23 7.3 4.0
19000 -15.7 3.7 300 46 24 7.6 4.2 | -15.7 3.7 295 44 23 7.3 4.0
18500 -14.8 5.4 300 45 23 4.9 2.7 | -14.8 5.4 295 43 22 6.2 3.4
18000 -14.0 6.8 300 43 22 5.2 2.9 | -13.8 7.2 295 41 21 6.3 3.4
17500 -13.3 8.1 305 41 21 5.2 2.9 | -12.9 8.8 295 40 20 5.3 2.9
17000 -12.5 9.5 305 38 20 5.2 2.9 | -12.2 10.0 295 37 19 4.9 2.7
16500 -11.7 10.9 305 35 18 5.2 2.9 | -11.5 11.3 300 35 18 4.7 2.6
16000 -11.0 12.2 305 33 17 4.7 2.6 | -10.9 12.4 300 33 17 3.9 2.2
15500 -10.3 13.5 305 30 16 4.7 2.6 | -10.3 13.5 300 30 15 3.9 2.2
15000 -9.6 14.7 305 28 14 5.1 2.8 | -9.7 14.5 300 27 14 5.0 2.7
14500 -8.9 16.0 305 25 13 5.1 2.8 | -9.0 15.8 300 25 13 4.9 2.7
14000 -8.2 17.2 310 23 12 4.9 2.7 | -8.3 17.1 300 22 11 5.7 3.1
13500 -7.5 18.5 310 21 11 4.9 2.7 | -7.4 18.7 300 20 10 5.8 3.2
13000 -6.8 19.8 315 18 9 5.0 2.7 | -6.5 20.3 300 18 9 6.7 3.7
12500 -6.0 21.2 315 16 8 5.1 2.8 | -5.5 22.1 300 16 8 7.1 3.9
12000 -5.3 22.5 315 14 7 5.4 3.0 | -4.5 23.9 295 14 7 7.3 4.0
11500 -4.5 23.9 315 12 6 5.7 3.1 | -3.4 25.9 295 12 6 7.4 4.0
11000 -3.6 25.5 310 10 5 6.3 3.5 | -2.3 27.9 290 11 5 7.8 4.3
10500 -2.6 27.3 305 8 4 7.1 3.9 | -1.1 30.0 285 9 5 8.5 4.7
10250 -2.1 28.2 305 7 4 5.3 2.9 | -0.5 31.1 280 9 5 6.0 3.3
10000 -1.8 28.8 300 7 4 5.8 3.2 | -0.1 31.8 275 9 4 6.8 3.7
9750 -1.2 29.8 300 6 3 8.0 4.4 | 0.6 33.1 275 8 4 9.8 5.4
9500 -0.7 30.7 295 5 3 7.6 4.1 | 1.2 34.2 275 8 4 9.2 5.1
9250 -0.1 31.8 290 4 2 7.3 4.0 | 1.9 35.4 275 8 4 8.6 4.7
9000 0.4 32.7 280 4 2 6.6 3.6 | 2.5 36.5 270 7 4 8.2 4.5
8750 0.9 33.6 275 3 2 6.9 3.8 | 3.2 37.8 270 7 4 9.0 5.0
8500 1.4 34.5 270 3 1 7.7 4.2 | 3.9 39.0 270 7 4 9.6 5.3
8250 2.3 36.1 240 2 1 4.3 2.3 | 5.0 41.0 270 6 3 6.8 3.7
8000 2.7 36.9 220 1 1 7.4 4.0 | 5.7 42.3 275 6 3 10.3 5.6
7750 3.4 38.1 205 1 1 9.0 4.9 | 6.5 43.7 275 6 3 11.3 6.2
7500 3.9 39.0 195 1 1 6.3 3.5 | 7.3 45.1 275 6 3 8.7 4.8
7250 4.3 39.7 180 1 1 4.2 2.3 | 7.8 46.0 275 6 3 7.1 3.9
7000 4.7 40.5 165 1 1 9.1 5.0 | 8.5 47.3 280 6 3 11.9 6.5
6750 5.6 42.1 175 1 1 11.6 6.3 | 9.5 49.1 275 5 3 13.1 7.2
6500 6.3 43.3 175 1 1 9.2 5.1 | 10.3 50.5 280 5 3 10.2 5.6
6250 7.0 44.6 170 1 1 9.0 4.9 | 11.1 52.0 280 5 3 9.7 5.3
6000 7.7 45.9 165 1 1 11.1 6.1 | 11.9 53.4 280 5 3 12.8 7.0
5750 8.8 47.8 180 1 1 19.0 10.4 | 13.2 55.8 280 5 2 25.6 14.0
5500 10.4 50.7 175 1 0 21.7 11.9 | 15.6 60.1 285 5 2 35.1 19.3
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

05/20/2025 at 1500 MDT | 05/20/2025 at 1800 MDT
|
CAPE... 0.0 LI... +4.2 | CAPE... +0.3 LI... +2.6
CINH... -0.1 K Index... +11.4 | CINH... -0.2 K Index... +15.9
|
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 -57.8 -72.0 260 35 18 1.9 1.1 | -57.9 -72.2 260 36 18 1.8 1.0
45000 -55.0 -67.0 265 50 26 1.3 0.7 | -55.3 -67.5 270 50 26 0.7 0.4
40000 -53.1 -63.6 275 71 37 1.3 0.7 | -54.4 -65.9 275 66 34 0.7 0.4
38000 -52.4 -62.3 275 72 37 1.0 0.5 | -53.3 -63.9 280 66 34 2.2 1.2
36000 -51.8 -61.2 280 67 34 1.0 0.5 | -51.8 -61.2 280 63 32 2.2 1.2
34000 -49.9 -57.8 280 64 33 6.8 3.7 | -49.4 -56.9 285 61 31 6.7 3.7
32000 -45.9 -50.6 285 64 33 6.7 3.7 | -45.4 -49.7 285 60 31 6.7 3.7
30000 -41.6 -42.9 290 63 32 7.5 4.1 | -41.2 -42.2 285 59 30 7.4 4.1
29000 -39.4 -38.9 290 61 31 7.5 4.1 | -39.0 -38.2 285 59 30 7.4 4.1
28000 -37.1 -34.8 290 59 30 7.5 4.1 | -36.8 -34.2 285 59 30 7.4 4.1
27000 -34.9 -30.8 290 57 29 7.9 4.3 | -34.5 -30.1 285 59 30 8.2 4.5
26000 -32.5 -26.5 290 56 29 7.9 4.3 | -32.1 -25.8 285 58 30 8.1 4.4
25000 -30.1 -22.2 290 54 28 7.9 4.3 | -29.7 -21.5 285 56 29 8.1 4.4
24000 -27.8 -18.0 285 53 27 8.2 4.5 | -27.2 -17.0 285 55 29 8.0 4.4
23000 -25.3 -13.5 285 51 26 8.3 4.6 | -24.3 -11.7 290 54 28 8.0 4.4
22000 -22.2 -8.0 285 50 26 8.3 4.5 | -21.9 -7.4 290 53 27 7.9 4.4
21000 -19.8 -3.6 285 48 25 7.3 4.0 | -19.7 -3.5 290 50 26 6.4 3.5
20000 -17.6 0.3 285 46 23 7.3 4.0 | -17.8 -0.0 290 47 24 6.4 3.5
19500 -16.6 2.1 290 44 23 7.3 4.0 | -16.9 1.6 290 46 24 6.4 3.5
19000 -15.5 4.1 290 43 22 7.2 3.9 | -15.9 3.4 290 44 23 6.3 3.5
18500 -14.5 5.9 290 42 22 6.2 3.4 | -15.1 4.8 290 42 22 5.4 3.0
18000 -13.6 7.5 290 40 21 6.3 3.5 | -14.3 6.3 290 40 20 5.5 3.0
17500 -12.7 9.1 290 39 20 5.5 3.0 | -13.5 7.7 295 38 19 5.8 3.2
17000 -11.9 10.6 290 36 19 5.3 2.9 | -12.6 9.3 295 35 18 6.0 3.3
16500 -11.2 11.8 290 34 18 5.1 2.8 | -11.8 10.8 295 32 17 6.6 3.6
16000 -10.5 13.1 290 32 16 4.5 2.5 | -10.7 12.7 295 30 15 7.7 4.2
15500 -9.9 14.2 290 29 15 4.5 2.5 | -9.6 14.7 290 28 14 7.8 4.3
15000 -9.1 15.6 290 26 13 6.3 3.5 | -8.4 16.9 290 26 13 8.4 4.6
14500 -8.2 17.2 290 23 12 6.1 3.3 | -7.2 19.0 290 24 12 8.4 4.6
14000 -7.2 19.0 285 20 11 7.7 4.2 | -5.9 21.4 285 23 12 8.6 4.7
13500 -6.1 21.0 285 18 10 7.7 4.2 | -4.6 23.7 280 22 11 8.6 4.7
13000 -4.9 23.2 280 17 9 8.3 4.6 | -3.3 26.1 280 21 11 9.1 5.0
12500 -3.6 25.5 280 16 8 8.5 4.6 | -2.0 28.4 275 20 10 9.2 5.0
12000 -2.4 27.7 275 15 8 8.8 4.8 | -0.6 30.9 275 20 10 9.2 5.0
11500 -1.0 30.2 275 14 7 9.0 4.9 | 0.8 33.4 270 19 10 9.2 5.1
11000 0.3 32.5 270 14 7 8.4 4.6 | 2.1 35.8 270 19 10 8.2 4.5
10500 1.5 34.7 270 13 7 7.6 4.2 | 3.3 37.9 265 19 10 6.8 3.7
10250 2.1 35.8 270 13 7 10.5 5.8 | 3.9 39.0 265 19 10 11.8 6.5
10000 3.0 37.4 270 13 7 11.1 6.1 | 5.0 41.0 265 19 10 12.6 6.9
9750 3.7 38.7 265 13 7 8.5 4.7 | 5.6 42.1 265 19 10 8.1 4.4
9500 4.4 39.9 265 13 7 9.5 5.2 | 6.3 43.3 265 18 10 9.6 5.3
9250 5.0 41.0 265 13 6 8.3 4.5 | 7.0 44.6 265 18 9 8.0 4.4
9000 5.6 42.1 270 12 6 8.6 4.7 | 7.6 45.7 265 18 9 8.6 4.7
8750 6.3 43.3 265 12 6 9.6 5.3 | 9.0 48.2 265 17 9 10.0 5.5
8500 7.0 44.6 265 12 6 9.8 5.4 | 9.8 49.6 265 17 9 9.2 5.0
8250 7.7 45.9 265 11 6 8.5 4.6 | 10.4 50.7 260 17 9 8.9 4.9
8000 9.0 48.2 270 11 6 11.1 6.1 | 11.1 52.0 260 17 9 10.2 5.6
7750 9.9 49.8 270 11 6 11.7 6.4 | 11.9 53.4 260 17 9 10.7 5.8
7500 10.7 51.3 270 11 6 8.7 4.8 | 12.7 54.9 260 16 8 9.1 5.0
7250 11.2 52.2 270 11 6 7.0 3.8 | 13.3 55.9 260 17 9 8.2 4.5
7000 11.9 53.4 270 11 6 11.7 6.4 | 14.0 57.2 260 17 9 10.4 5.7
6750 12.9 55.2 270 10 5 12.9 7.1 | 14.8 58.6 260 16 8 11.3 6.2
6500 13.7 56.7 270 10 5 10.2 5.6 | 15.6 60.1 260 15 8 10.5 5.8
6250 14.5 58.1 275 10 5 9.7 5.3 | 16.4 61.5 260 15 8 10.8 5.9
6000 15.2 59.4 275 10 5 11.6 6.4 | 17.2 63.0 260 15 8 8.8 4.8
5750 16.5 61.7 270 9 5 23.6 13.0 | 17.8 64.0 260 13 7 11.3 6.2
5500 19.1 66.4 280 9 4 50.8 27.9 | 19.8 67.6 260 12 6 53.4 29.3
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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