Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
516
UXUS97 KGJT 231306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Monday, June 23, 2025
This forecast is for Monday, June 23, 2025:
If the trigger temperature of 74.3 F/23.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1136 ft/min (5.8 m/s)
Maximum height of thermals.................. 18031 ft MSL (13192 ft AGL)
Forecast maximum temperature................... 89.0 F/32.1 C
Time of trigger temperature.................... 1030 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................. 15979 ft MSL (11139 ft AGL)
Thermal soaring outlook for Tuesday 06/24...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:49:01 / 20:44:00 MDT
Total possible sunshine........... 14 hr 54 min 59 sec (894 min 59 sec)
Altitude of sun at 13:16:30 MDT... 73.91 degrees
Upper air data from rawinsonde observation taken on 06/23/2025 at 0600 MDT
Freezing level.................. 14056 ft MSL (9217 ft AGL)
Convective condensation level... 21627 ft MSL (16788 ft AGL)
Lifted condensation level....... 20428 ft MSL (15589 ft AGL)
Lifted index.................... +2.0
K index......................... +7.5
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 -63.9 -83.0 225 59 30 -2.0 -1.1 89.2 192.6 33.2 M M
45000 -57.2 -71.0 220 74 38 5.1 2.8 74.8 166.6 26.8 M M
40000 -49.5 -57.1 220 85 44 -2.8 -1.5 63.9 147.1 21.4 M M
38000 -47.2 -53.0 230 88 45 4.6 2.5 58.7 137.7 18.4 M M
36000 -44.6 -48.3 225 90 47 4.4 2.4 54.1 129.4 15.7 M M
34000 -41.7 -43.1 225 78 40 5.0 2.7 49.9 121.8 13.0 M M
32000 -37.0 -34.6 225 74 38 10.0 5.5 47.3 117.2 11.5 M M
30000 -32.8 -27.0 225 69 35 7.8 4.3 45.1 113.1 10.1 M M
29000 -30.4 -22.7 225 66 34 8.3 4.5 44.4 111.8 9.7 M M
28000 -29.1 -20.4 225 64 33 5.0 2.8 42.3 108.2 8.3 M M
27000 -27.3 -17.1 220 60 31 6.9 3.8 40.9 105.6 7.2 M M
26000 -25.2 -13.4 225 50 26 6.9 3.8 39.8 103.7 6.4 M M
25000 -23.2 -9.8 225 52 27 6.9 3.8 38.7 101.7 5.6 M M
24000 -21.1 -6.0 225 48 25 6.9 3.8 37.7 99.9 4.9 M M
23000 -19.0 -2.2 225 48 25 8.1 4.4 36.7 98.1 4.1 M M
22000 -16.5 2.3 220 50 26 8.7 4.8 36.2 97.2 3.7 M M
21000 -13.9 7.0 220 48 24 8.6 4.7 35.8 96.5 3.5 M M
20000 -11.3 11.7 220 46 24 8.6 4.7 35.4 95.8 3.1 M M
19500 -10.0 14.0 220 45 23 7.7 4.2 35.2 95.4 3.0 M M
19000 -9.0 15.8 220 41 21 6.5 3.5 34.7 94.5 2.6 M M
18500 -8.1 17.4 225 38 20 4.5 2.4 34.0 93.3 1.9 M M
18000 -8.3 17.1 215 32 17 -4.9 -2.7 32.2 89.9 0.3 M M
17500 -8.4 16.9 210 31 16 5.4 3.0 30.4 86.8 -1.2 1125 5.7
17000 -7.0 19.4 195 34 18 6.7 3.7 29.6 85.3 -2.0 1060 5.4
16500 -6.0 21.2 200 31 16 6.8 3.7 29.1 84.4 -2.6 1017 5.2
16000 -5.1 22.8 210 27 14 7.4 4.1 28.6 83.5 -3.1 974 4.9
15500 -3.8 25.2 215 26 13 9.2 5.1 28.5 83.2 -3.2 920 4.7
15000 -2.4 27.7 210 24 12 9.2 5.0 28.4 83.1 -3.3 864 4.4
14500 -1.0 30.2 210 27 14 9.2 5.0 28.3 83.0 -3.4 808 4.1
14000 0.3 32.5 210 28 14 9.2 5.0 28.3 82.9 -3.5 752 3.8
13500 1.7 35.1 210 25 13 9.2 5.0 28.2 82.7 -3.6 696 3.5
13000 3.1 37.6 205 23 12 9.2 5.0 28.1 82.5 -3.7 640 3.3
12500 4.5 40.1 200 20 10 9.2 5.0 28.0 82.3 -3.8 584 3.0
12000 5.8 42.4 195 16 8 9.2 5.0 27.9 82.2 -3.9 528 2.7
11500 7.2 45.0 185 17 9 9.2 5.0 27.7 81.9 -4.0 472 2.4
11000 8.6 47.5 175 19 10 9.2 5.0 27.6 81.7 -4.1 416 2.1
10500 10.0 50.0 170 19 10 9.3 5.1 27.5 81.5 -4.3 360 1.8
10250 10.6 51.1 170 19 10 8.7 4.8 27.4 81.4 -4.4 332 1.7
10000 11.3 52.3 180 14 7 8.9 4.9 27.3 81.2 -4.5 306 1.6
9750 11.9 53.4 180 14 7 7.0 3.8 27.2 81.0 -4.6 279 1.4
9500 12.2 54.0 175 10 5 -0.4 -0.2 26.8 80.2 -5.1 264 1.3
9250 11.9 53.4 155 5 3 -3.9 -2.2 25.7 78.3 -6.1 264 1.3
9000 11.7 53.1 080 4 2 -3.3 -1.8 24.7 76.5 -7.1 265 1.3
8750 11.4 52.5 080 4 2 -3.1 -1.7 23.7 74.6 -8.1 265 1.3
8500 11.1 52.0 075 5 3 -4.4 -2.4 22.6 72.8 -9.1 266 1.4
8250 10.8 51.4 075 6 3 0.6 0.3 21.6 70.9 -10.2 267 1.4
8000 11.2 52.2 070 7 4 7.0 3.8 21.3 70.3 -10.5 249 1.3
7750 11.7 53.1 065 7 4 6.6 3.6 21.0 69.9 -10.8 226 1.1
7500 12.2 54.0 060 8 4 6.7 3.7 20.8 69.4 -11.0 204 1.0
7250 12.7 54.9 050 8 4 6.7 3.7 20.6 69.0 -11.3 181 0.9
7000 13.2 55.8 045 7 4 6.7 3.7 20.3 68.6 -11.5 159 0.8
6750 13.7 56.7 045 7 4 6.7 3.7 20.1 68.2 -11.8 137 0.7
6500 14.2 57.6 050 6 3 6.7 3.7 19.9 67.8 -12.1 114 0.6
6250 14.7 58.5 065 5 2 6.7 3.7 19.6 67.3 -12.3 92 0.5
6000 15.2 59.4 065 4 2 6.7 3.7 19.4 66.9 -12.6 69 0.4
5750 15.7 60.3 050 4 2 6.7 3.7 19.2 66.5 -12.9 47 0.2
5500 16.2 61.2 020 4 2 6.7 3.7 18.9 66.1 -13.1 24 0.1
5250 16.7 62.1 010 4 2 6.6 3.6 18.7 65.6 -13.4 2 0.0
5000 17.2 63.0 010 6 3 7.2 3.9 18.5 65.2 -13.7 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/23/2025 at 0900 MDT | 06/23/2025 at 1200 MDT
|
CAPE... 0.0 LI... +5.3 | CAPE... 0.0 LI... +4.7
CINH... -0.3 K Index... +4.3 | CINH... -0.0 K Index... +5.0
|
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 -61.4 -78.5 220 48 25 2.5 1.4 | -61.3 -78.3 215 49 25 1.8 1.0
45000 -56.9 -70.4 215 66 34 4.5 2.4 | -57.7 -71.9 220 70 36 4.5 2.5
40000 -49.9 -57.8 215 81 42 4.7 2.6 | -50.6 -59.1 220 86 44 4.8 2.6
38000 -47.0 -52.6 220 81 42 4.7 2.6 | -47.7 -53.9 220 84 43 4.8 2.6
36000 -44.2 -47.6 220 81 42 4.7 2.6 | -44.8 -48.6 220 83 43 4.8 2.6
34000 -40.9 -41.6 225 79 41 5.9 3.3 | -41.3 -42.3 220 80 41 6.3 3.5
32000 -37.3 -35.1 225 75 38 5.9 3.3 | -37.5 -35.5 220 76 39 6.3 3.5
30000 -33.4 -28.1 225 69 36 6.7 3.7 | -33.2 -27.8 225 71 37 7.6 4.1
29000 -31.4 -24.5 225 66 34 6.7 3.7 | -30.9 -23.6 220 69 35 7.6 4.1
28000 -29.4 -20.9 225 63 33 6.8 3.7 | -28.7 -19.7 220 66 34 7.7 4.2
27000 -27.6 -17.7 220 59 31 5.8 3.2 | -26.8 -16.2 220 62 32 5.7 3.1
26000 -25.4 -13.7 220 54 28 5.8 3.2 | -24.6 -12.3 220 56 29 5.7 3.1
25000 -23.7 -10.7 220 49 25 5.6 3.1 | -22.9 -9.2 220 51 26 5.6 3.0
24000 -21.6 -6.9 220 46 24 7.8 4.3 | -20.9 -5.6 215 48 25 7.0 3.8
23000 -19.2 -2.6 220 44 23 7.8 4.3 | -18.8 -1.8 215 45 23 7.0 3.8
22000 -16.9 1.6 220 42 21 7.8 4.3 | -16.7 1.9 215 42 22 7.0 3.9
21000 -14.6 5.7 215 41 21 7.9 4.3 | -14.4 6.1 215 40 21 8.1 4.4
20000 -12.2 10.0 215 40 21 7.9 4.3 | -11.9 10.6 215 40 20 8.1 4.4
19500 -11.0 12.2 215 40 21 7.9 4.3 | -10.7 12.7 215 39 20 8.1 4.5
19000 -9.9 14.2 210 40 21 6.9 3.8 | -9.6 14.7 215 39 20 7.3 4.0
18500 -8.9 16.0 210 40 20 6.7 3.7 | -8.5 16.7 210 38 20 7.2 4.0
18000 -7.9 17.8 210 40 20 6.6 3.6 | -7.4 18.7 210 38 19 7.1 3.9
17500 -7.0 19.4 210 39 20 5.8 3.2 | -6.4 20.5 210 37 19 6.4 3.5
17000 -6.1 21.0 210 38 20 5.9 3.2 | -5.5 22.1 210 37 19 6.5 3.6
16500 -5.2 22.6 210 37 19 5.8 3.2 | -4.6 23.7 210 36 18 5.8 3.2
16000 -4.4 24.1 210 36 19 5.9 3.2 | -3.7 25.3 210 35 18 5.8 3.2
15500 -3.6 25.5 210 35 18 6.5 3.5 | -2.9 26.8 205 34 17 6.1 3.3
15000 -2.5 27.5 210 33 17 7.1 3.9 | -2.0 28.4 205 32 16 6.3 3.5
14500 -1.5 29.3 210 30 16 7.4 4.1 | -1.1 30.0 205 30 16 6.6 3.6
14000 -0.3 31.5 210 28 15 8.6 4.7 | -0.0 32.0 205 28 15 7.6 4.1
13500 0.9 33.6 210 27 14 8.5 4.7 | 1.1 34.0 205 26 14 7.5 4.1
13000 2.2 36.0 210 25 13 8.9 4.9 | 2.3 36.1 205 24 13 8.7 4.8
12500 3.5 38.3 210 24 12 8.9 4.9 | 3.5 38.3 210 23 12 8.6 4.7
12000 4.8 40.6 210 22 12 8.1 4.5 | 4.8 40.6 210 21 11 8.9 4.9
11500 6.0 42.8 205 21 11 8.3 4.6 | 6.1 43.0 210 20 10 9.0 4.9
11000 7.2 45.0 205 20 10 6.5 3.6 | 7.4 45.3 210 18 9 7.9 4.3
10500 8.1 46.6 200 18 9 6.9 3.8 | 8.6 47.5 210 17 9 7.4 4.0
10250 8.6 47.5 200 17 9 4.7 2.6 | 9.2 48.6 210 16 8 10.3 5.7
10000 8.9 48.0 200 16 8 4.0 2.2 | 10.1 50.2 210 16 8 10.6 5.8
9750 9.3 48.7 195 15 8 5.7 3.1 | 10.7 51.3 210 15 8 7.7 4.2
9500 9.7 49.5 190 13 7 5.3 2.9 | 11.4 52.5 210 14 7 8.8 4.8
9250 10.0 50.0 190 12 6 5.2 2.9 | 12.0 53.6 210 14 7 7.4 4.0
9000 10.4 50.7 180 12 6 4.1 2.2 | 12.5 54.5 210 11 6 7.2 4.0
8750 10.9 51.6 175 8 4 3.5 1.9 | 13.7 56.7 215 10 5 8.1 4.5
8500 11.2 52.2 170 7 4 3.2 1.8 | 14.2 57.6 215 9 4 5.4 3.0
8250 11.4 52.5 160 7 4 3.1 1.7 | 14.6 58.3 220 7 3 6.4 3.5
8000 11.6 52.9 155 6 3 3.5 1.9 | 15.3 59.5 220 6 3 11.1 6.1
7750 11.9 53.4 135 4 2 3.2 1.8 | 16.1 61.0 220 7 3 10.4 5.7
7500 12.1 53.8 120 3 2 2.4 1.3 | 16.8 62.2 225 6 3 7.6 4.2
7250 12.3 54.1 105 3 2 2.0 1.1 | 17.3 63.1 230 5 3 7.3 4.0
7000 12.6 54.7 090 3 2 7.8 4.3 | 18.0 64.4 230 5 3 12.6 6.9
6750 13.3 55.9 070 3 2 9.6 5.3 | 19.1 66.4 230 6 3 12.7 7.0
6500 13.9 57.0 065 3 2 7.0 3.8 | 19.8 67.6 235 5 3 9.8 5.4
6250 14.4 57.9 065 3 1 6.8 3.7 | 20.6 69.1 240 4 2 9.5 5.2
6000 15.0 59.0 060 3 1 11.1 6.1 | 21.3 70.3 245 4 2 12.4 6.8
5750 16.3 61.3 055 2 1 22.5 12.4 | 22.7 72.9 240 5 2 25.2 13.8
5500 17.7 63.9 060 2 1 7.5 4.1 | 25.0 77.0 255 3 2 36.4 20.0
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
06/23/2025 at 1500 MDT | 06/23/2025 at 1800 MDT
|
CAPE... 0.0 LI... +2.9 | CAPE... +1.1 LI... +1.6
CINH... -0.2 K Index... +11.7 | CINH... -0.5 K Index... +14.9
|
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 -62.0 -79.6 220 57 29 1.6 0.9 | -61.6 -78.9 225 57 29 1.3 0.7
45000 -58.5 -73.3 225 77 40 4.5 2.5 | -58.2 -72.8 230 77 40 4.4 2.4
40000 -51.3 -60.3 220 90 46 4.8 2.7 | -51.6 -60.9 225 90 46 5.1 2.8
38000 -48.4 -55.1 220 85 44 4.8 2.6 | -48.5 -55.3 220 85 44 5.1 2.8
36000 -45.5 -49.9 220 81 42 4.9 2.7 | -45.5 -49.9 220 81 42 5.1 2.8
34000 -41.9 -43.4 220 75 39 6.6 3.6 | -41.8 -43.2 220 73 38 6.5 3.6
32000 -37.9 -36.2 220 68 35 6.6 3.6 | -37.9 -36.2 220 65 33 6.5 3.6
30000 -33.3 -27.9 220 63 33 8.2 4.5 | -33.3 -27.9 220 59 30 8.3 4.5
29000 -30.8 -23.4 220 62 32 8.2 4.5 | -30.8 -23.4 220 57 29 8.3 4.5
28000 -28.3 -18.9 220 60 31 8.4 4.6 | -27.7 -17.9 220 54 28 7.7 4.2
27000 -26.3 -15.3 220 57 29 6.4 3.5 | -25.5 -13.9 220 53 27 7.2 3.9
26000 -23.9 -11.0 220 54 28 6.4 3.5 | -23.4 -10.1 220 51 27 7.1 3.9
25000 -22.0 -7.6 220 51 26 6.4 3.5 | -21.2 -6.2 220 50 26 7.3 4.0
24000 -20.0 -4.0 220 49 25 6.6 3.6 | -19.4 -2.9 220 48 25 6.0 3.3
23000 -18.0 -0.4 215 47 24 6.6 3.6 | -17.6 0.3 220 46 24 6.0 3.3
22000 -16.1 3.0 215 44 23 6.7 3.7 | -15.8 3.6 215 44 22 6.1 3.3
21000 -13.9 7.0 215 42 22 7.2 4.0 | -13.9 7.0 215 40 21 6.5 3.6
20000 -11.8 10.8 210 39 20 7.2 4.0 | -12.0 10.4 210 36 19 6.6 3.6
19500 -10.7 12.7 210 38 20 7.3 4.0 | -11.1 12.0 210 34 18 6.6 3.6
19000 -9.7 14.5 210 37 19 6.9 3.8 | -10.1 13.8 210 32 17 7.3 4.0
18500 -8.6 16.5 210 35 18 6.9 3.8 | -9.0 15.8 205 31 16 7.3 4.0
18000 -7.6 18.3 210 33 17 6.9 3.8 | -7.9 17.8 200 29 15 7.4 4.1
17500 -6.7 19.9 210 31 16 6.7 3.6 | -6.8 19.8 200 27 14 7.7 4.2
17000 -5.7 21.7 205 29 15 6.6 3.6 | -5.7 21.7 200 26 13 7.6 4.1
16500 -4.7 23.5 205 28 14 7.4 4.1 | -4.5 23.9 195 25 13 8.8 4.9
16000 -3.6 25.5 205 26 14 7.5 4.1 | -3.2 26.2 195 23 12 8.8 4.8
15500 -2.5 27.5 200 25 13 8.2 4.5 | -1.9 28.6 195 22 11 9.1 5.0
15000 -1.3 29.7 200 24 12 8.6 4.7 | -0.5 31.1 195 21 11 9.3 5.1
14500 0.0 32.0 200 22 12 8.8 4.8 | 0.9 33.6 195 20 10 9.3 5.1
14000 1.3 34.3 200 21 11 9.0 5.0 | 2.3 36.1 200 19 10 9.4 5.1
13500 2.7 36.9 200 20 10 9.0 4.9 | 3.7 38.7 200 18 9 9.3 5.1
13000 4.0 39.2 205 19 10 8.9 4.9 | 5.1 41.2 200 17 9 9.2 5.0
12500 5.4 41.7 205 18 9 8.9 4.9 | 6.5 43.7 205 16 8 9.2 5.1
12000 6.7 44.1 205 16 8 8.8 4.8 | 7.8 46.0 205 15 7 8.8 4.8
11500 8.0 46.4 210 15 8 8.9 4.9 | 9.2 48.6 210 14 7 9.0 4.9
11000 9.3 48.7 215 13 7 7.8 4.3 | 10.4 50.7 215 12 6 7.5 4.1
10500 10.4 50.7 220 12 6 8.2 4.5 | 11.5 52.7 220 11 6 8.2 4.5
10250 11.1 52.0 225 11 6 10.2 5.6 | 12.2 54.0 225 11 6 10.7 5.9
10000 11.9 53.4 225 12 6 9.8 5.4 | 13.0 55.4 225 11 6 9.8 5.4
9750 12.5 54.5 230 11 6 8.3 4.6 | 13.7 56.7 230 10 5 8.1 4.4
9500 13.2 55.8 235 11 6 8.8 4.8 | 15.0 59.0 240 10 5 7.7 4.2
9250 13.8 56.8 240 11 5 8.4 4.6 | 15.5 59.9 250 9 5 8.3 4.5
9000 14.5 58.1 250 10 5 9.0 4.9 | 16.2 61.2 250 10 5 9.6 5.2
8750 15.9 60.6 250 10 5 9.6 5.2 | 16.9 62.4 255 10 5 9.6 5.3
8500 16.6 61.9 255 10 5 9.0 4.9 | 17.6 63.7 260 10 5 7.9 4.4
8250 17.3 63.1 260 10 5 9.6 5.2 | 18.2 64.8 265 10 5 8.2 4.5
8000 18.1 64.6 260 10 5 10.9 6.0 | 18.9 66.0 265 10 5 10.4 5.7
7750 18.9 66.0 260 10 5 10.4 5.7 | 19.7 67.5 265 10 5 10.0 5.5
7500 19.6 67.3 260 10 5 8.6 4.7 | 20.4 68.7 270 10 5 8.7 4.8
7250 20.2 68.4 265 10 5 8.5 4.7 | 21.0 69.8 275 10 5 8.5 4.6
7000 20.9 69.6 270 10 5 11.6 6.3 | 21.7 71.1 275 10 5 10.8 5.9
6750 21.9 71.4 265 10 5 11.9 6.5 | 22.6 72.7 270 10 5 11.1 6.1
6500 22.7 72.9 270 10 5 10.6 5.8 | 23.3 73.9 275 10 5 10.0 5.5
6250 23.5 74.3 275 10 5 10.2 5.6 | 24.1 75.4 275 10 5 10.1 5.5
6000 24.2 75.6 275 10 5 11.2 6.2 | 24.8 76.6 280 10 5 8.8 4.8
5750 25.4 77.7 270 10 5 22.8 12.5 | 25.5 77.9 275 9 5 13.3 7.3
5500 28.2 82.8 280 10 5 58.7 32.2 | 27.6 81.7 285 9 5 52.7 28.9
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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