Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
895
UXUS97 KGJT 221306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Sunday, June 22, 2025
This forecast is for Sunday, June 22, 2025:
If the trigger temperature of 79.7 F/26.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1030 ft/min (5.2 m/s)
Maximum height of thermals.................. 16080 ft MSL (11241 ft AGL)
Forecast maximum temperature................... 86.0 F/30.5 C
Time of trigger temperature.................... 1000 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................. 10312 ft MSL (5473 ft AGL)
Thermal soaring outlook for Monday 06/23....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:48:44 / 20:43:50 MDT
Total possible sunshine........... 14 hr 55 min 6 sec (895 min 6 sec)
Altitude of sun at 13:16:17 MDT... 73.94 degrees
Upper air data from rawinsonde observation taken on 06/22/2025 at 0600 MDT
Freezing level.................. 14555 ft MSL (9716 ft AGL)
Convective condensation level... 19255 ft MSL (14416 ft AGL)
Lifted condensation level....... 17743 ft MSL (12904 ft AGL)
Lifted index.................... +2.3
K index......................... +8.8
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 -62.7 -80.9 215 46 24 7.0 3.9 89.6 193.3 34.6 M M
45000 -59.3 -74.7 230 81 42 4.7 2.6 71.0 159.8 25.5 M M
40000 -51.2 -60.2 230 81 42 2.8 1.5 60.9 141.6 20.6 M M
38000 -47.6 -53.7 225 79 41 7.1 3.9 56.5 133.7 18.1 M M
36000 -43.3 -45.9 225 76 39 7.0 3.8 54.1 129.4 16.9 M M
34000 -40.0 -40.0 225 88 45 8.0 4.4 50.5 122.9 14.8 M M
32000 -35.6 -32.1 225 88 45 6.8 3.7 48.5 119.3 13.6 M M
30000 -30.6 -23.1 220 77 40 9.4 5.1 47.4 117.3 13.1 M M
29000 -27.8 -18.0 220 72 37 8.3 4.5 47.2 116.9 13.1 M M
28000 -25.5 -13.9 225 65 34 7.3 4.0 46.5 115.6 12.7 M M
27000 -23.9 -11.0 220 66 34 8.4 4.6 44.7 112.4 11.5 M M
26000 -21.9 -7.4 220 63 32 5.6 3.1 43.5 110.3 10.7 M M
25000 -20.7 -5.3 215 63 32 4.8 2.6 41.4 106.6 9.2 M M
24000 -19.2 -2.6 210 60 31 6.0 3.3 39.7 103.5 7.8 M M
23000 -17.1 1.2 210 60 31 8.5 4.6 38.7 101.6 7.0 M M
22000 -14.6 5.7 210 60 31 8.1 4.4 38.2 100.7 6.7 M M
21000 -12.6 9.3 210 58 30 6.5 3.6 37.1 98.7 5.8 M M
20000 -10.3 13.5 210 54 28 7.3 4.0 35.5 95.8 4.5 M M
19500 -9.4 15.1 210 54 28 6.5 3.6 34.9 94.8 4.0 M M
19000 -8.5 16.7 215 53 27 5.2 2.9 34.3 93.7 3.5 M M
18500 -7.9 17.8 220 48 25 4.5 2.5 33.3 92.0 2.6 M M
18000 -7.2 19.0 220 44 22 4.8 2.7 32.4 90.4 1.8 M M
17500 -6.4 20.5 215 37 19 6.0 3.3 31.7 89.0 1.1 M M
17000 -5.6 21.9 210 32 16 6.1 3.4 31.0 87.9 0.6 M M
16500 -4.5 23.9 215 32 16 7.8 4.3 30.6 87.1 0.2 M M
16000 -3.3 26.1 210 33 17 7.7 4.2 30.3 86.5 -0.1 1015 5.2
15500 -2.1 28.2 210 32 16 7.7 4.2 29.9 85.9 -0.4 965 4.9
15000 -1.0 30.2 225 38 20 7.6 4.1 29.6 85.2 -0.7 915 4.6
14500 0.3 32.5 225 38 20 7.7 4.2 29.3 84.7 -0.9 863 4.4
14000 1.1 34.0 225 32 17 7.7 4.2 28.7 83.7 -1.5 823 4.2
13500 2.7 36.9 225 32 16 9.7 5.3 28.8 83.8 -1.5 762 3.9
13000 3.7 38.7 220 30 15 6.3 3.5 28.4 83.2 -1.9 714 3.6
12500 4.9 40.8 225 27 14 9.5 5.2 28.1 82.5 -2.2 666 3.4
12000 6.3 43.3 225 27 14 9.7 5.3 28.1 82.6 -2.2 608 3.1
11500 7.8 46.0 220 28 15 9.8 5.4 28.1 82.6 -2.3 550 2.8
11000 9.2 48.6 215 27 14 9.8 5.4 28.1 82.6 -2.3 491 2.5
10500 10.3 50.5 225 22 11 4.8 2.6 27.7 81.8 -2.7 445 2.3
10250 10.7 51.3 220 20 10 8.3 4.6 27.4 81.3 -3.1 425 2.2
10000 11.4 52.5 220 18 9 10.0 5.5 27.4 81.3 -3.1 396 2.0
9750 12.1 53.8 220 18 9 8.7 4.8 27.4 81.3 -3.1 369 1.9
9500 12.7 54.9 220 17 9 9.1 5.0 27.3 81.2 -3.2 341 1.7
9250 13.4 56.1 215 16 8 9.0 4.9 27.3 81.1 -3.2 314 1.6
9000 14.1 57.4 210 16 8 9.0 4.9 27.2 81.0 -3.3 286 1.5
8750 14.7 58.5 200 16 8 9.0 4.9 27.2 80.9 -3.4 259 1.3
8500 15.4 59.7 190 17 9 9.0 4.9 27.1 80.8 -3.4 232 1.2
8250 16.1 61.0 185 19 10 9.0 4.9 27.1 80.7 -3.5 204 1.0
8000 16.7 62.1 175 21 11 9.0 4.9 27.0 80.6 -3.6 177 0.9
7750 17.4 63.3 180 21 11 9.0 4.9 27.0 80.5 -3.6 149 0.8
7500 18.1 64.6 170 21 11 9.0 4.9 26.9 80.4 -3.7 122 0.6
7250 18.7 65.7 165 22 11 9.0 4.9 26.8 80.3 -3.8 95 0.5
7000 19.4 66.9 160 23 12 9.0 4.9 26.8 80.2 -3.9 67 0.3
6750 20.1 68.2 160 23 12 9.0 4.9 26.7 80.1 -3.9 40 0.2
6500 20.7 69.3 160 25 13 9.0 4.9 26.7 80.0 -4.0 12 0.1
6250 21.4 70.5 155 27 14 9.0 4.9 26.6 79.9 -4.1 M M
6000 22.1 71.8 155 29 15 9.0 4.9 26.5 79.7 -4.2 M M
5750 22.7 72.9 155 30 15 9.0 5.0 26.5 79.6 -4.3 M M
5500 23.4 74.1 155 30 16 8.8 4.8 26.4 79.5 -4.4 M M
5250 24.1 75.4 155 29 15 9.6 5.3 26.3 79.4 -4.4 M M
5000 24.7 76.5 150 21 11 7.6 4.2 26.3 79.3 -4.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/22/2025 at 0900 MDT | 06/22/2025 at 1200 MDT
|
CAPE... 0.0 LI... +4.8 | CAPE... 0.0 LI... +3.3
CINH... -0.0 K Index... +9.7 | CINH... 0.0 K Index... +15.5
|
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 -62.5 -80.5 215 50 26 2.5 1.4 | -61.9 -79.4 210 49 25 2.0 1.1
45000 -57.6 -71.7 215 74 38 5.5 3.0 | -57.6 -71.7 215 74 38 5.8 3.2
40000 -49.0 -56.2 220 89 46 5.0 2.7 | -48.5 -55.3 220 91 47 5.1 2.8
38000 -46.0 -50.8 220 88 45 5.0 2.7 | -45.4 -49.7 220 91 47 5.1 2.8
36000 -43.0 -45.4 220 86 44 5.0 2.8 | -42.4 -44.3 220 92 47 5.2 2.8
34000 -39.4 -38.9 220 86 44 6.4 3.5 | -38.9 -38.0 220 92 47 6.0 3.3
32000 -35.5 -31.9 220 85 44 6.4 3.5 | -35.4 -31.7 220 92 47 5.9 3.3
30000 -31.3 -24.3 220 83 43 7.4 4.0 | -31.4 -24.5 220 90 46 7.1 3.9
29000 -29.1 -20.4 215 82 42 7.4 4.0 | -29.2 -20.6 220 89 46 7.1 3.9
28000 -26.9 -16.4 215 81 42 7.4 4.0 | -27.1 -16.8 220 87 45 7.1 3.9
27000 -25.0 -13.0 215 79 41 5.7 3.1 | -25.1 -13.2 220 85 44 6.0 3.3
26000 -23.3 -9.9 215 77 39 5.7 3.1 | -23.3 -9.9 220 83 43 6.0 3.3
25000 -21.6 -6.9 215 74 38 5.7 3.1 | -21.5 -6.7 220 80 41 6.0 3.3
24000 -19.4 -2.9 215 72 37 6.3 3.5 | -19.2 -2.6 215 77 39 6.4 3.5
23000 -17.5 0.5 215 69 36 6.3 3.5 | -17.3 0.9 215 74 38 6.4 3.5
22000 -15.6 3.9 215 67 34 6.4 3.5 | -15.4 4.3 215 71 37 6.5 3.6
21000 -13.7 7.3 215 64 33 6.2 3.4 | -13.8 7.2 215 68 35 4.9 2.7
20000 -11.9 10.6 215 61 32 6.2 3.4 | -12.3 9.9 215 64 33 5.0 2.7
19500 -11.0 12.2 215 60 31 6.2 3.4 | -11.6 11.1 215 62 32 5.0 2.7
19000 -10.1 13.8 215 59 30 6.0 3.3 | -10.9 12.4 215 61 31 4.6 2.5
18500 -9.3 15.3 215 57 29 5.5 3.0 | -10.3 13.5 215 58 30 3.8 2.1
18000 -8.4 16.9 215 55 28 5.5 3.0 | -9.8 14.4 220 54 28 3.8 2.1
17500 -7.6 18.3 215 54 28 5.3 2.9 | -9.2 15.4 220 51 26 4.6 2.5
17000 -6.9 19.6 215 52 27 5.3 2.9 | -8.6 16.5 220 48 25 4.7 2.6
16500 -6.1 21.0 215 51 26 5.2 2.8 | -7.9 17.8 220 45 23 5.6 3.1
16000 -5.4 22.3 220 49 25 5.0 2.7 | -7.0 19.4 220 43 22 6.8 3.7
15500 -4.6 23.7 220 47 24 5.0 2.7 | -6.0 21.2 220 41 21 6.9 3.8
15000 -3.8 25.2 220 45 23 5.8 3.2 | -4.8 23.4 220 38 20 8.1 4.5
14500 -3.0 26.6 220 43 22 5.6 3.1 | -3.7 25.3 220 36 18 8.0 4.4
14000 -2.1 28.2 220 40 21 7.1 3.9 | -2.4 27.7 220 34 17 8.8 4.8
13500 -1.1 30.0 220 38 19 7.2 3.9 | -1.1 30.0 220 32 16 8.8 4.8
13000 0.0 32.0 220 35 18 8.2 4.5 | 0.2 32.4 215 30 16 9.1 5.0
12500 1.3 34.3 220 33 17 8.5 4.7 | 1.5 34.7 220 29 15 9.2 5.0
12000 2.5 36.5 220 31 16 8.7 4.8 | 2.9 37.2 220 28 14 9.2 5.0
11500 3.8 38.8 220 29 15 8.8 4.8 | 4.3 39.7 220 27 14 9.1 5.0
11000 5.1 41.2 220 27 14 8.1 4.4 | 5.6 42.1 220 26 14 8.5 4.7
10500 6.3 43.3 220 26 13 6.9 3.8 | 6.8 44.2 220 25 13 7.4 4.1
10250 6.8 44.2 220 25 13 10.5 5.8 | 7.4 45.3 225 25 13 11.0 6.0
10000 7.8 46.0 220 24 12 11.0 6.0 | 8.4 47.1 225 25 13 11.4 6.3
9750 8.4 47.1 220 23 12 7.5 4.1 | 9.1 48.4 225 24 12 8.2 4.5
9500 9.0 48.2 220 22 11 8.9 4.9 | 9.7 49.5 225 23 12 8.8 4.8
9250 9.6 49.3 220 21 11 6.9 3.8 | 10.4 50.7 230 23 12 9.7 5.3
9000 10.0 50.0 225 20 10 6.8 3.7 | 11.2 52.2 230 22 12 10.1 5.5
8750 10.6 51.1 225 19 10 8.3 4.6 | 12.6 54.7 230 21 11 9.5 5.2
8500 11.8 53.2 225 17 9 7.2 3.9 | 13.3 55.9 235 21 11 9.1 5.0
8250 12.3 54.1 230 15 8 6.3 3.5 | 13.9 57.0 235 20 10 9.4 5.2
8000 12.8 55.0 230 15 7 7.5 4.1 | 14.7 58.5 240 20 10 10.0 5.5
7750 13.4 56.1 230 14 7 8.6 4.7 | 15.4 59.7 240 19 10 10.3 5.6
7500 14.0 57.2 235 13 7 6.3 3.5 | 16.2 61.2 240 19 10 9.3 5.1
7250 14.4 57.9 240 12 6 4.6 2.5 | 16.8 62.2 240 19 10 8.5 4.7
7000 14.8 58.6 245 12 6 9.1 5.0 | 17.5 63.5 245 19 10 10.4 5.7
6750 15.7 60.3 245 11 6 11.7 6.4 | 18.3 64.9 245 18 9 11.4 6.3
6500 16.5 61.7 245 11 6 10.2 5.6 | 19.2 66.6 245 18 9 11.2 6.1
6250 17.2 63.0 250 11 6 10.2 5.6 | 20.1 68.2 245 18 9 12.3 6.7
6000 18.0 64.4 250 11 6 8.6 4.7 | 20.9 69.6 250 18 9 8.1 4.4
5750 18.6 65.5 250 10 5 12.5 6.9 | 21.5 70.7 245 16 8 13.4 7.4
5500 20.9 69.6 255 9 5 59.8 32.8 | 24.9 76.8 250 15 8 102.2 56.1
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
06/22/2025 at 1500 MDT | 06/22/2025 at 1800 MDT
|
CAPE... +0.3 LI... +1.5 | CAPE... 0.0 LI... +1.1
CINH... -0.4 K Index... +16.5 | CINH... -0.1 K Index... +15.0
|
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 -61.5 -78.7 215 55 28 2.9 1.6 | -61.2 -78.2 225 57 29 3.3 1.8
45000 -56.6 -69.9 220 74 38 4.5 2.5 | -56.1 -69.0 225 75 39 3.6 2.0
40000 -49.4 -56.9 220 94 48 5.2 2.9 | -50.3 -58.5 230 97 50 5.3 2.9
38000 -46.3 -51.3 220 94 49 5.2 2.8 | -47.2 -53.0 225 96 49 5.2 2.8
36000 -43.2 -45.8 220 95 49 5.2 2.9 | -44.1 -47.4 225 95 49 5.2 2.8
34000 -39.5 -39.1 220 95 49 6.6 3.6 | -40.5 -40.9 225 92 47 6.3 3.5
32000 -35.5 -31.9 220 95 49 6.6 3.6 | -36.7 -34.1 225 88 45 6.3 3.5
30000 -31.6 -24.9 220 92 47 6.4 3.5 | -32.8 -27.0 230 82 42 6.7 3.7
29000 -29.7 -21.5 220 89 46 6.4 3.5 | -30.8 -23.4 230 79 41 6.7 3.7
28000 -27.8 -18.0 225 87 45 6.4 3.5 | -28.8 -19.8 230 76 39 6.7 3.7
27000 -25.8 -14.4 225 84 43 6.3 3.5 | -26.8 -16.2 230 74 38 6.7 3.7
26000 -24.0 -11.2 225 81 42 6.3 3.5 | -24.8 -12.6 230 71 37 6.7 3.7
25000 -22.1 -7.8 225 78 40 6.3 3.5 | -22.2 -8.0 230 68 35 6.8 3.7
24000 -19.7 -3.5 225 75 38 6.5 3.6 | -20.3 -4.5 230 66 34 6.5 3.6
23000 -17.7 0.1 225 73 38 6.5 3.6 | -18.3 -0.9 230 63 32 6.5 3.6
22000 -15.7 3.7 220 71 37 6.7 3.7 | -16.4 2.5 230 60 31 6.7 3.7
21000 -14.3 6.3 220 66 34 4.0 2.2 | -14.8 5.4 230 55 28 4.5 2.5
20000 -13.1 8.4 220 60 31 4.1 2.2 | -13.5 7.7 225 48 25 4.6 2.5
19500 -12.6 9.3 220 57 29 4.2 2.3 | -12.8 9.0 225 44 23 4.8 2.6
19000 -12.0 10.4 220 54 28 4.6 2.5 | -12.2 10.0 225 41 21 6.0 3.3
18500 -11.3 11.7 220 50 26 5.1 2.8 | -11.2 11.8 220 38 19 6.9 3.8
18000 -10.6 12.9 215 47 24 4.9 2.7 | -10.2 13.6 220 34 18 7.0 3.8
17500 -9.6 14.7 215 43 22 8.0 4.4 | -9.1 15.6 215 32 16 8.7 4.8
17000 -8.5 16.7 215 40 21 7.8 4.3 | -7.8 18.0 215 30 15 8.6 4.7
16500 -7.4 18.7 215 37 19 8.4 4.6 | -6.6 20.1 215 28 14 9.0 5.0
16000 -6.1 21.0 215 36 18 8.8 4.8 | -5.2 22.6 215 27 14 9.2 5.1
15500 -4.8 23.4 210 34 17 8.9 4.9 | -3.8 25.2 215 26 13 9.1 5.0
15000 -3.5 25.7 215 33 17 9.1 5.0 | -2.5 27.5 220 25 13 8.9 4.9
14500 -2.1 28.2 215 31 16 9.0 5.0 | -1.2 29.8 220 25 13 8.9 4.9
14000 -0.8 30.6 215 30 16 9.2 5.0 | 0.2 32.4 220 24 12 9.4 5.2
13500 0.6 33.1 215 29 15 9.2 5.0 | 1.6 34.9 220 24 12 9.4 5.1
13000 1.9 35.4 215 28 15 8.9 4.9 | 3.0 37.4 225 23 12 9.3 5.1
12500 3.3 37.9 220 27 14 8.9 4.9 | 4.4 39.9 225 23 12 9.3 5.1
12000 4.6 40.3 220 26 13 8.9 4.9 | 5.8 42.4 225 22 11 9.1 5.0
11500 5.9 42.6 225 25 13 8.9 4.9 | 7.1 44.8 230 22 11 9.1 5.0
11000 7.2 45.0 225 24 13 7.8 4.3 | 8.4 47.1 230 21 11 7.7 4.2
10500 8.3 46.9 230 23 12 6.7 3.7 | 9.5 49.1 235 21 11 7.0 3.9
10250 8.9 48.0 230 23 12 10.9 6.0 | 10.2 50.4 235 21 11 11.4 6.3
10000 9.8 49.6 235 23 12 11.2 6.1 | 11.1 52.0 235 20 10 11.4 6.3
9750 10.5 50.9 240 22 11 7.6 4.2 | 11.8 53.2 240 20 10 7.7 4.2
9500 11.1 52.0 240 22 11 8.1 4.4 | 12.4 54.3 240 20 10 9.0 5.0
9250 11.7 53.1 245 21 11 9.8 5.4 | 13.1 55.6 240 20 10 7.6 4.1
9000 12.5 54.5 245 22 11 10.7 5.9 | 13.6 56.5 245 20 10 8.2 4.5
8750 13.2 55.8 245 21 11 9.2 5.1 | 15.0 59.0 250 19 10 9.6 5.3
8500 14.7 58.5 250 21 11 8.7 4.8 | 15.8 60.4 250 19 10 8.6 4.7
8250 15.3 59.5 255 21 11 9.0 5.0 | 16.4 61.5 250 19 10 8.7 4.8
8000 16.0 60.8 255 20 10 10.5 5.8 | 17.1 62.8 250 19 10 10.2 5.6
7750 16.8 62.2 255 20 10 11.0 6.1 | 17.9 64.2 250 18 9 10.5 5.8
7500 17.6 63.7 255 20 10 9.1 5.0 | 18.6 65.5 255 18 9 8.9 4.9
7250 18.2 64.8 260 20 10 7.7 4.2 | 19.2 66.6 255 18 10 7.9 4.3
7000 18.9 66.0 260 20 10 10.6 5.8 | 19.9 67.8 255 18 10 10.5 5.8
6750 19.7 67.5 260 19 10 11.8 6.5 | 20.7 69.3 255 17 9 11.5 6.3
6500 20.6 69.1 260 19 10 10.7 5.9 | 21.6 70.9 255 17 9 10.6 5.8
6250 21.4 70.5 265 19 10 10.9 6.0 | 22.4 72.3 255 17 9 10.8 5.9
6000 22.2 72.0 265 19 10 8.6 4.7 | 23.1 73.6 255 17 9 8.3 4.6
5750 22.9 73.2 265 17 9 15.5 8.5 | 23.7 74.7 255 15 8 10.6 5.8
5500 26.1 79.0 270 16 8 89.7 49.2 | 25.9 78.6 260 14 7 60.2 33.0
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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