Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
179
UXUS97 KGJT 071306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Friday, February 7, 2025
This forecast is for Friday, February 7, 2025:
If the trigger temperature of 58.5 F/14.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 904 ft/min (4.6 m/s)
Maximum height of thermals.................. 14936 ft MSL (10097 ft AGL)
Forecast maximum temperature................... 64.0 F/18.2 C
Time of trigger temperature.................... 1145 MST
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................. 8470 ft MSL (3631 ft AGL)
Thermal soaring outlook for Saturday 02/08..... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:14:15 / 17:42:20 MST
Total possible sunshine........... 10 hr 28 min 5 sec (628 min 5 sec)
Altitude of sun at 12:28:17 MST... 35.44 degrees
Upper air data from rawinsonde observation taken on 02/07/2025 at 0500 MST
Freezing level.................. 9804 ft MSL (4965 ft AGL)
Convective condensation level... 21693 ft MSL (16854 ft AGL)
Lifted condensation level....... 16841 ft MSL (12002 ft AGL)
Lifted index.................... +9.1
K index......................... +8.9
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 -60.6 -77.1 260 91 47 5.1 2.8 99.8 211.6 46.7 M M
45000 -55.6 -68.1 265 117 60 5.5 3.0 82.1 179.8 39.4 M M
40000 -55.0 -67.0 265 132 68 -6.0 -3.3 60.1 140.1 27.7 M M
38000 -55.0 -67.0 265 122 63 2.0 1.1 51.3 124.4 22.5 M M
36000 -53.9 -65.0 270 117 60 4.1 2.3 44.3 111.8 18.3 M M
34000 -51.7 -61.1 260 112 58 7.6 4.2 39.2 102.5 15.2 M M
32000 -46.4 -51.5 260 105 54 8.1 4.4 37.3 99.2 14.3 M M
30000 -41.4 -42.5 260 96 49 7.1 3.9 36.1 97.0 13.7 M M
29000 -39.3 -38.7 260 96 49 7.2 3.9 35.1 95.2 13.1 M M
28000 -36.8 -34.2 260 92 47 9.9 5.4 34.6 94.3 12.9 M M
27000 -33.8 -28.8 260 91 47 9.0 4.9 34.7 94.4 13.1 M M
26000 -31.5 -24.7 260 90 46 9.1 5.0 33.9 92.9 12.6 M M
25000 -28.8 -19.8 260 88 45 8.5 4.7 33.6 92.6 12.6 M M
24000 -26.5 -15.7 260 85 44 8.2 4.5 32.9 91.2 12.1 M M
23000 -23.8 -10.8 260 86 44 8.9 4.9 32.5 90.5 11.9 M M
22000 -21.2 -6.2 265 86 44 8.8 4.8 32.2 90.0 11.8 M M
21000 -18.9 -2.0 260 84 43 6.5 3.6 31.5 88.6 11.3 M M
20000 -16.8 1.8 260 79 40 7.0 3.9 30.5 86.8 10.6 M M
19500 -15.8 3.6 260 76 39 7.0 3.8 30.0 85.9 10.2 M M
19000 -14.7 5.5 260 74 38 6.0 3.3 29.5 85.0 9.8 M M
18500 -14.0 6.8 260 74 38 6.1 3.4 28.6 83.4 9.1 M M
18000 -12.7 9.1 260 74 38 9.8 5.4 28.4 83.1 9.0 M M
17500 -10.9 12.4 255 68 35 6.3 3.5 27.9 82.2 8.7 M M
17000 -10.0 14.0 250 59 30 -1.6 -0.9 27.3 81.2 8.3 M M
16500 -10.9 12.4 250 58 30 -4.5 -2.5 24.6 76.3 5.9 M M
16000 -12.0 10.4 250 49 25 -8.1 -4.4 21.7 71.1 3.3 M M
15500 -12.7 9.1 250 41 21 -1.9 -1.0 19.4 67.0 1.2 M M
15000 -12.5 9.5 245 32 16 7.6 4.2 18.1 64.6 -0.0 903 4.6
14500 -11.5 11.3 245 33 17 7.3 4.0 17.6 63.6 -0.5 861 4.4
14000 -10.4 13.3 240 35 18 8.0 4.4 17.3 63.1 -0.8 811 4.1
13500 -9.2 15.4 240 33 17 8.1 4.4 17.0 62.6 -1.1 761 3.9
13000 -8.0 17.6 240 34 18 8.1 4.5 16.8 62.2 -1.3 709 3.6
12500 -6.7 19.9 240 34 17 8.2 4.5 16.5 61.7 -1.6 658 3.3
12000 -5.5 22.1 240 30 15 8.2 4.5 16.3 61.3 -1.8 606 3.1
11500 -4.3 24.3 245 29 15 8.2 4.5 16.0 60.8 -2.0 554 2.8
11000 -3.0 26.6 240 26 13 8.2 4.5 15.7 60.3 -2.3 502 2.6
10500 -1.8 28.8 235 24 12 8.2 4.5 15.5 59.8 -2.5 451 2.3
10250 -1.2 29.8 230 23 12 8.0 4.4 15.3 59.6 -2.6 425 2.2
10000 -0.6 30.9 230 23 12 8.6 4.7 15.2 59.4 -2.8 399 2.0
9750 0.1 32.2 235 25 13 9.3 5.1 15.2 59.3 -2.8 371 1.9
9500 0.8 33.4 230 23 12 9.2 5.1 15.1 59.3 -2.8 343 1.7
9250 1.5 34.7 225 22 11 9.2 5.1 15.1 59.2 -2.9 314 1.6
9000 2.2 36.0 230 21 11 9.2 5.1 15.1 59.1 -2.9 286 1.5
8750 2.9 37.2 225 20 10 9.2 5.1 15.0 59.1 -3.0 258 1.3
8500 3.6 38.5 220 21 11 9.2 5.1 15.0 59.0 -3.0 230 1.2
8250 4.3 39.7 220 20 10 9.2 5.1 15.0 58.9 -3.0 201 1.0
8000 5.0 41.0 215 18 9 9.2 5.1 14.9 58.9 -3.1 173 0.9
7750 5.7 42.3 215 18 9 9.2 5.1 14.9 58.8 -3.1 145 0.7
7500 6.4 43.5 210 17 9 9.2 5.1 14.8 58.7 -3.2 116 0.6
7250 7.1 44.8 205 17 9 9.2 5.1 14.8 58.6 -3.2 88 0.4
7000 7.8 46.0 205 15 8 9.2 5.1 14.8 58.6 -3.3 60 0.3
6750 8.5 47.3 205 15 8 9.3 5.1 14.7 58.5 -3.3 32 0.2
6500 9.2 48.6 200 14 7 9.2 5.0 14.6 58.4 -3.4 3 0.0
6250 9.9 49.8 190 14 7 9.5 5.2 14.6 58.3 -3.4 M M
6000 10.6 51.1 185 14 7 8.4 4.6 14.5 58.2 -3.5 M M
5750 11.2 52.2 185 16 8 11.0 6.1 14.5 58.1 -3.6 M M
5500 11.9 53.4 185 13 7 -0.2 -0.1 14.4 57.9 -3.7 M M
5250 11.0 51.8 175 8 4 -17.7 -9.7 12.8 55.1 -5.3 M M
5000 9.7 49.5 155 4 2 -13.2 -7.2 10.8 51.4 -7.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/07/2025 at 0800 MST | 02/07/2025 at 1100 MST
|
CAPE... 0.0 LI... +5.1 | CAPE... 0.0 LI... +6.1
CINH... -0.1 K Index... +10.7 | CINH... -0.1 K Index... +5.2
|
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 -59.9 -75.8 265 82 42 1.6 0.9 | -59.3 -74.7 260 76 39 0.9 0.5
45000 -57.4 -71.3 260 112 58 1.6 0.9 | -57.7 -71.9 260 108 56 3.0 1.7
40000 -55.1 -67.2 260 121 62 1.6 0.9 | -53.5 -64.3 260 121 62 2.8 1.6
38000 -54.0 -65.2 260 117 60 1.9 1.0 | -52.4 -62.3 260 116 60 1.1 0.6
36000 -52.8 -63.0 265 108 56 1.9 1.0 | -51.6 -60.9 255 105 54 1.1 0.6
34000 -50.7 -59.3 265 102 52 8.3 4.5 | -49.8 -57.6 255 97 50 7.4 4.0
32000 -45.6 -50.1 265 100 52 8.5 4.7 | -45.3 -49.5 255 94 48 7.5 4.1
30000 -40.6 -41.1 265 98 50 7.9 4.4 | -40.6 -41.1 255 92 48 8.7 4.8
29000 -38.2 -36.8 260 96 49 8.0 4.4 | -38.0 -36.4 255 93 48 8.7 4.8
28000 -35.8 -32.4 260 94 48 8.0 4.4 | -35.4 -31.7 255 93 48 8.7 4.8
27000 -32.9 -27.2 260 91 47 7.3 4.0 | -32.8 -27.0 255 93 48 8.0 4.4
26000 -30.7 -23.3 260 88 45 7.3 4.0 | -30.6 -23.1 255 91 47 7.5 4.1
25000 -28.5 -19.3 260 86 44 7.4 4.0 | -28.3 -18.9 255 89 46 7.6 4.1
24000 -26.3 -15.3 260 83 43 7.3 4.0 | -26.1 -15.0 255 86 44 7.5 4.1
23000 -24.1 -11.4 260 80 41 7.3 4.0 | -24.1 -11.4 255 84 43 6.7 3.7
22000 -22.6 -8.7 260 77 40 7.3 4.0 | -21.6 -6.9 255 81 42 6.7 3.7
21000 -19.8 -3.6 260 75 38 6.5 3.6 | -19.6 -3.3 255 79 40 6.5 3.6
20000 -17.9 -0.2 260 70 36 6.5 3.6 | -17.7 0.1 255 75 39 6.5 3.6
19500 -16.9 1.6 260 68 35 6.5 3.6 | -16.7 1.9 255 73 38 6.5 3.6
19000 -15.9 3.4 260 66 34 6.5 3.6 | -15.8 3.6 255 71 37 6.5 3.6
18500 -14.9 5.2 260 64 33 6.2 3.4 | -14.8 5.4 255 69 36 6.2 3.4
18000 -14.0 6.8 255 62 32 6.1 3.3 | -13.9 7.0 255 67 34 6.1 3.3
17500 -13.1 8.4 255 59 30 6.0 3.3 | -13.0 8.6 255 65 33 6.1 3.3
17000 -12.3 9.9 255 57 29 5.4 3.0 | -12.1 10.2 255 62 32 5.8 3.2
16500 -11.5 11.3 255 55 28 5.5 3.0 | -11.2 11.8 255 60 31 5.9 3.2
16000 -10.7 12.7 255 53 27 4.8 2.6 | -10.3 13.5 250 58 30 5.3 2.9
15500 -10.0 14.0 255 51 26 4.6 2.5 | -9.6 14.7 250 56 29 5.2 2.9
15000 -9.4 15.1 250 49 25 4.2 2.3 | -8.8 16.2 250 53 27 4.8 2.7
14500 -8.9 16.0 250 46 24 3.7 2.0 | -8.1 17.4 250 50 26 4.5 2.5
14000 -8.3 17.1 250 43 22 4.0 2.2 | -7.5 18.5 250 47 24 4.3 2.4
13500 -7.7 18.1 250 41 21 4.8 2.7 | -6.9 19.6 245 43 22 3.8 2.1
13000 -7.0 19.4 250 38 20 4.9 2.7 | -6.4 20.5 245 40 20 3.8 2.1
12500 -6.3 20.7 245 36 19 5.2 2.8 | -5.9 21.4 240 36 18 3.8 2.1
12000 -5.6 21.9 245 35 18 5.2 2.9 | -5.4 22.3 240 32 17 4.0 2.2
11500 -4.7 23.5 245 34 18 6.2 3.4 | -4.6 23.7 235 31 16 6.4 3.5
11000 -3.8 25.2 240 35 18 6.1 3.4 | -3.7 25.3 235 31 16 6.2 3.4
10500 -2.9 26.8 240 35 18 6.0 3.3 | -2.8 27.0 235 31 16 6.3 3.5
10250 -2.5 27.5 240 35 18 5.8 3.2 | -2.3 27.9 235 31 16 6.5 3.5
10000 -2.0 28.4 240 35 18 7.7 4.2 | -1.8 28.8 235 30 16 8.1 4.4
9750 -1.3 29.7 235 34 18 8.6 4.7 | -1.1 30.0 230 30 15 8.5 4.6
9500 -0.8 30.6 235 33 17 7.6 4.2 | -0.6 30.9 230 29 15 7.7 4.2
9250 -0.2 31.6 235 33 17 7.9 4.3 | 0.0 32.0 230 29 15 8.1 4.4
9000 1.0 33.8 230 31 16 7.6 4.2 | 0.6 33.1 230 28 14 7.3 4.0
8750 1.6 34.9 230 30 15 7.6 4.2 | 1.1 34.0 225 27 14 7.4 4.0
8500 2.2 36.0 225 28 15 7.6 4.2 | 2.3 36.1 225 26 13 7.9 4.4
8250 2.8 37.0 225 27 14 7.6 4.2 | 3.0 37.4 220 25 13 8.3 4.5
8000 3.4 38.1 225 26 13 7.2 3.9 | 3.6 38.5 225 23 12 8.0 4.4
7750 3.9 39.0 220 24 12 7.2 3.9 | 4.2 39.6 220 22 11 7.6 4.1
7500 4.4 39.9 215 22 12 6.5 3.6 | 4.8 40.6 215 21 11 7.7 4.2
7250 4.9 40.8 210 21 11 4.8 2.6 | 5.3 41.5 215 20 10 7.6 4.2
7000 5.2 41.4 205 20 10 4.8 2.6 | 5.9 42.6 215 19 10 8.7 4.8
6750 5.6 42.1 200 17 9 5.4 2.9 | 6.7 44.1 210 18 9 9.6 5.3
6500 6.0 42.8 190 15 8 4.6 2.5 | 7.4 45.3 210 16 8 9.8 5.4
6250 6.4 43.5 180 14 7 4.4 2.4 | 8.2 46.8 210 15 8 11.3 6.2
6000 6.7 44.1 170 13 7 3.4 1.9 | 8.9 48.0 210 14 7 7.9 4.3
5750 6.6 43.9 165 10 5 -6.5 -3.6 | 9.4 48.9 205 13 7 6.5 3.6
5500 5.2 41.4 150 6 3 -35.8 -19.6 | 11.0 51.8 205 9 5 50.9 27.9
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
02/07/2025 at 1400 MST | 02/07/2025 at 1700 MST
|
CAPE... +0.1 LI... +5.0 | CAPE... 0.0 LI... +4.3
CINH... -1.0 K Index... +7.9 | CINH... -0.4 K Index... +10.6
|
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 -59.8 -75.6 260 71 36 1.2 0.7 | -59.2 -74.6 260 66 34 1.5 0.8
45000 -57.8 -72.0 260 104 54 3.9 2.1 | -56.8 -70.2 260 100 52 3.8 2.1
40000 -52.3 -62.1 260 117 60 3.7 2.0 | -51.5 -60.7 260 114 59 3.6 2.0
38000 -50.9 -59.6 260 115 59 1.5 0.8 | -50.0 -58.0 260 117 60 1.4 0.8
36000 -49.9 -57.8 255 109 56 1.5 0.8 | -49.1 -56.4 260 118 61 1.4 0.8
34000 -48.2 -54.8 255 103 53 5.8 3.2 | -47.5 -53.5 260 116 60 6.0 3.3
32000 -44.7 -48.5 255 98 50 5.9 3.2 | -43.8 -46.8 255 107 55 6.2 3.4
30000 -40.8 -41.4 255 94 48 8.1 4.4 | -40.0 -40.0 255 99 51 6.5 3.6
29000 -38.4 -37.1 255 93 48 8.1 4.5 | -38.1 -36.6 255 97 50 6.5 3.6
28000 -35.9 -32.6 255 92 47 8.1 4.5 | -36.2 -33.2 255 94 48 6.5 3.6
27000 -33.5 -28.3 250 91 47 8.2 4.5 | -34.2 -29.6 255 92 47 6.9 3.8
26000 -31.0 -23.8 250 91 47 8.3 4.5 | -31.9 -25.4 255 89 46 7.8 4.3
25000 -28.5 -19.3 250 91 47 8.3 4.6 | -29.6 -21.3 255 86 44 7.8 4.3
24000 -26.1 -15.0 250 90 47 8.3 4.5 | -26.7 -16.1 255 83 43 7.6 4.2
23000 -23.5 -10.3 250 87 45 6.6 3.6 | -24.5 -12.1 255 82 42 7.4 4.1
22000 -21.5 -6.7 255 84 43 6.7 3.7 | -22.3 -8.1 255 81 42 7.4 4.1
21000 -19.6 -3.3 255 81 42 6.1 3.4 | -20.2 -4.4 260 80 41 6.4 3.5
20000 -17.8 -0.0 255 78 40 6.1 3.4 | -18.3 -0.9 260 76 39 6.3 3.5
19500 -16.9 1.6 255 76 39 6.1 3.4 | -17.4 0.7 260 75 38 6.3 3.5
19000 -16.0 3.2 255 74 38 6.1 3.4 | -16.4 2.5 260 73 38 6.3 3.4
18500 -15.1 4.8 255 73 37 5.9 3.2 | -15.5 4.1 260 71 37 5.8 3.2
18000 -14.2 6.4 255 70 36 5.8 3.2 | -14.7 5.5 260 69 35 5.4 3.0
17500 -13.4 7.9 255 68 35 5.7 3.1 | -13.9 7.0 260 66 34 5.4 2.9
17000 -12.5 9.5 255 66 34 5.6 3.1 | -13.1 8.4 255 63 32 5.2 2.8
16500 -11.7 10.9 250 63 32 5.6 3.1 | -12.4 9.7 255 60 31 5.2 2.8
16000 -10.9 12.4 250 60 31 5.3 2.9 | -11.6 11.1 255 57 29 5.5 3.0
15500 -10.1 13.8 250 57 29 5.2 2.8 | -10.8 12.6 255 53 28 5.6 3.0
15000 -9.3 15.3 250 54 28 5.1 2.8 | -10.0 14.0 255 50 26 5.7 3.1
14500 -8.6 16.5 250 51 26 4.9 2.7 | -9.1 15.6 250 47 24 5.8 3.2
14000 -7.9 17.8 250 47 24 5.0 2.7 | -8.3 17.1 250 44 23 5.8 3.2
13500 -7.2 19.0 245 44 23 5.0 2.8 | -7.5 18.5 250 41 21 5.6 3.1
13000 -6.5 20.3 245 42 22 5.1 2.8 | -6.7 19.9 245 39 20 5.7 3.1
12500 -5.7 21.7 240 40 21 5.6 3.1 | -5.7 21.7 240 38 19 7.0 3.8
12000 -4.9 23.2 240 39 20 5.6 3.1 | -4.8 23.4 240 37 19 6.9 3.8
11500 -4.0 24.8 235 38 20 7.1 3.9 | -3.7 25.3 235 37 19 7.7 4.2
11000 -3.0 26.6 235 37 19 7.0 3.8 | -2.6 27.3 235 37 19 7.6 4.2
10500 -1.9 28.6 235 36 18 7.9 4.3 | -1.4 29.5 235 36 19 8.1 4.5
10250 -1.3 29.7 230 34 18 8.1 4.4 | -0.8 30.6 235 36 18 8.3 4.6
10000 -0.6 30.9 230 34 18 9.2 5.1 | -0.1 31.8 235 36 18 9.3 5.1
9750 0.0 32.0 230 34 18 9.2 5.0 | 0.6 33.1 230 36 18 9.4 5.2
9500 0.7 33.3 230 33 17 8.6 4.7 | 1.2 34.2 230 35 18 9.0 5.0
9250 1.4 34.5 230 32 16 9.0 4.9 | 1.9 35.4 230 35 18 9.4 5.1
9000 2.0 35.6 230 31 16 8.1 4.4 | 3.2 37.8 230 33 17 8.3 4.6
8750 2.6 36.7 225 31 16 8.4 4.6 | 3.9 39.0 230 33 17 9.2 5.0
8500 3.3 37.9 225 30 16 9.6 5.3 | 4.5 40.1 230 32 16 8.8 4.8
8250 4.7 40.5 225 29 15 10.4 5.7 | 5.2 41.4 230 31 16 9.6 5.2
8000 5.5 41.9 230 27 14 10.0 5.5 | 5.9 42.6 230 31 16 9.3 5.1
7750 6.1 43.0 225 27 14 8.4 4.6 | 6.6 43.9 230 29 15 8.5 4.6
7500 6.8 44.2 225 26 13 8.8 4.9 | 7.2 45.0 230 28 14 8.7 4.8
7250 7.4 45.3 225 25 13 8.8 4.8 | 7.9 46.2 230 27 14 8.4 4.6
7000 8.1 46.6 230 25 13 9.4 5.2 | 8.5 47.3 235 27 14 8.7 4.8
6750 8.8 47.8 225 23 12 9.5 5.2 | 9.1 48.4 235 24 12 8.9 4.9
6500 9.6 49.3 225 22 11 10.1 5.5 | 9.8 49.6 235 21 11 9.3 5.1
6250 10.4 50.7 230 21 11 12.2 6.7 | 10.5 50.9 235 20 10 10.8 5.9
6000 11.2 52.2 230 20 10 8.2 4.5 | 11.3 52.3 235 19 10 8.2 4.5
5750 11.7 53.1 230 18 9 7.5 4.1 | 11.7 53.1 235 16 8 3.1 1.7
5500 13.7 56.7 230 15 7 64.2 35.2 | 12.2 54.0 235 12 6 17.5 9.6
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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