Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
347
UXUS97 KGJT 241305
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
605 AM MST Friday, January 24, 2025
This forecast is for Friday, January 24, 2025:
If the trigger temperature of 35.7 F/2.1 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 278 ft/min (1.4 m/s)
Maximum height of thermals.................. 9387 ft MSL (4548 ft AGL)
Forecast maximum temperature................... 39.0 F/4.3 C
Time of trigger temperature.................... 1330 MST
Time of overdevelopment........................ 1700 MST
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7744 ft MSL (2905 ft AGL)
Thermal soaring outlook for Saturday 01/25..... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:26:41 / 17:26:01 MST
Total possible sunshine........... 9 hr 59 min 19 sec (599 min 19 sec)
Altitude of sun at 12:26:21 MST... 31.55 degrees
Upper air data from rawinsonde observation taken on 01/24/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 22688 ft MSL (17849 ft AGL)
Lifted condensation level....... 14711 ft MSL (9872 ft AGL)
Lifted index.................... +17.0
K index......................... -21.7
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 -56.8 -70.2 290 54 28 -2.2 -1.2 109.8 229.7 59.9 M M
45000 -56.0 -68.8 275 46 24 -2.0 -1.1 86.1 187.0 49.7 M M
40000 -60.4 -76.7 295 73 38 3.7 2.0 55.7 132.2 33.5 M M
38000 -62.4 -80.3 295 63 33 -1.3 -0.7 43.6 110.5 26.4 M M
36000 -59.7 -75.5 305 67 34 6.6 3.6 37.8 100.0 23.2 M M
34000 -55.5 -67.9 305 63 32 6.1 3.3 35.5 95.8 22.3 M M
32000 -50.9 -59.6 305 61 32 8.1 4.4 33.7 92.7 21.6 M M
30000 -46.0 -50.8 300 57 29 8.1 4.4 32.4 90.3 21.2 M M
29000 -43.5 -46.3 300 58 30 8.2 4.5 31.8 89.2 21.0 M M
28000 -41.1 -42.0 305 55 28 7.0 3.8 31.1 87.9 20.7 M M
27000 -38.9 -38.0 310 54 28 7.7 4.2 30.2 86.3 20.3 M M
26000 -36.6 -33.9 305 51 26 7.6 4.1 29.4 84.8 19.9 M M
25000 -34.4 -29.9 305 51 26 7.6 4.1 28.5 83.3 19.5 M M
24000 -32.1 -25.8 310 51 26 7.6 4.2 27.7 81.8 19.0 M M
23000 -29.8 -21.6 305 49 25 7.1 3.9 26.9 80.5 18.6 M M
22000 -27.7 -17.9 305 49 25 6.7 3.7 25.9 78.7 18.0 M M
21000 -25.7 -14.3 300 42 21 6.6 3.6 24.8 76.7 17.3 M M
20000 -23.7 -10.7 305 39 20 6.7 3.7 23.7 74.7 16.6 M M
19500 -22.1 -7.8 310 37 19 7.2 3.9 22.9 73.2 16.1 M M
19000 -21.0 -5.8 315 37 19 7.4 4.0 22.5 72.5 15.9 M M
18500 -19.9 -3.8 315 36 19 7.7 4.2 22.1 71.8 15.6 M M
18000 -18.7 -1.7 310 34 17 7.8 4.3 21.8 71.2 15.4 M M
17500 -17.5 0.5 310 31 16 7.8 4.3 21.4 70.6 15.2 M M
17000 -16.4 2.5 315 31 16 7.9 4.4 21.1 69.9 15.0 M M
16500 -15.2 4.6 315 27 14 8.1 4.4 20.8 69.4 14.8 M M
16000 -14.0 6.8 310 27 14 8.1 4.4 20.5 68.9 14.6 M M
15500 -12.8 9.0 310 29 15 8.2 4.5 20.2 68.4 14.5 M M
15000 -11.7 10.9 300 28 14 4.5 2.5 19.7 67.5 14.1 M M
14500 -11.6 11.1 295 23 12 2.7 1.5 18.4 65.0 12.8 M M
14000 -10.9 12.4 305 22 11 5.4 3.0 17.6 63.7 12.2 M M
13500 -10.0 14.0 300 24 12 5.6 3.1 17.0 62.5 11.6 M M
13000 -9.3 15.3 290 21 11 3.6 2.0 16.1 61.0 10.9 M M
12500 -8.5 16.7 285 22 11 7.0 3.8 15.4 59.7 10.3 M M
12000 -7.6 18.3 295 23 12 5.8 3.2 14.8 58.6 9.8 M M
11500 -6.8 19.8 295 24 12 6.7 3.7 14.1 57.5 9.2 M M
11000 -6.3 20.7 280 13 7 -5.1 -2.8 13.1 55.7 8.3 M M
10500 -7.6 18.3 280 13 7 -10.7 -5.9 10.0 50.1 5.6 M M
10250 -8.3 17.1 270 13 7 -6.7 -3.7 8.5 47.2 4.2 M M
10000 -8.5 16.7 250 18 9 -1.5 -0.8 7.5 45.4 3.2 M M
9750 -8.7 16.3 250 19 10 -5.3 -2.9 6.4 43.6 2.3 M M
9500 -9.4 15.1 255 18 9 -13.0 -7.1 5.0 40.9 0.9 M M
9250 -10.3 13.5 255 17 9 -6.6 -3.6 3.2 37.8 -0.8 288 1.5
9000 -10.2 13.6 255 14 7 4.5 2.5 2.5 36.5 -1.4 279 1.4
8750 -9.9 14.2 250 11 6 4.3 2.4 2.1 35.8 -1.8 261 1.3
8500 -9.6 14.7 255 7 4 5.4 3.0 1.7 35.0 -2.2 243 1.2
8250 -9.1 15.6 300 3 1 6.9 3.8 1.4 34.6 -2.5 222 1.1
8000 -8.6 16.5 170 6 3 6.8 3.7 1.2 34.2 -2.7 199 1.0
7750 -8.1 17.4 160 7 3 6.6 3.6 1.0 33.8 -3.0 176 0.9
7500 -7.5 18.5 155 10 5 7.5 4.1 0.7 33.3 -3.2 154 0.8
7250 -7.1 19.2 150 13 7 1.4 0.8 0.4 32.8 -3.5 133 0.7
7000 -7.3 18.9 150 16 8 -2.3 -1.2 -0.5 31.1 -4.4 131 0.7
6750 -7.3 18.9 150 18 9 0.3 0.2 -1.2 29.8 -5.2 124 0.6
6500 -7.3 18.9 155 19 10 1.6 0.9 -2.0 28.5 -5.9 116 0.6
6250 -7.0 19.4 150 20 10 5.5 3.0 -2.4 27.6 -6.4 100 0.5
6000 -6.7 19.9 140 21 11 -1.2 -0.7 -2.9 26.8 -6.8 84 0.4
5750 -7.0 19.4 140 19 10 -2.2 -1.2 -3.9 24.9 -7.9 86 0.4
5500 -6.8 19.8 130 17 9 7.0 3.8 -4.4 24.0 -8.4 72 0.4
5250 -6.4 20.5 120 16 8 -0.1 -0.1 -4.8 23.4 -8.8 53 0.3
5000 -7.3 18.9 115 13 6 -23.9 -13.1 -6.3 20.6 -10.4 72 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
01/24/2025 at 0800 MST | 01/24/2025 at 1100 MST
|
CAPE... 0.0 LI... +6.9 | CAPE... 0.0 LI... +5.5
CINH... -0.0 K Index... -4.8 | CINH... 0.0 K Index... +0.6
|
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 -57.2 -71.0 285 49 25 1.6 0.9 | -57.1 -70.8 280 51 26 1.2 0.7
45000 -54.8 -66.6 285 54 28 2.0 1.1 | -55.1 -67.2 275 57 30 1.6 0.9
40000 -59.8 -75.6 285 66 34 -3.7 -2.0 | -59.6 -75.3 280 72 37 -3.3 -1.8
38000 -60.7 -77.3 285 71 36 3.6 2.0 | -60.2 -76.4 280 77 40 3.6 2.0
36000 -58.5 -73.3 285 73 37 3.7 2.0 | -58.0 -72.4 275 79 41 3.6 2.0
34000 -55.7 -68.3 285 75 38 7.8 4.3 | -55.8 -68.4 275 81 42 5.8 3.2
32000 -51.2 -60.2 285 72 37 7.6 4.2 | -51.3 -60.3 275 79 41 7.4 4.1
30000 -46.6 -51.9 290 69 36 7.5 4.1 | -46.9 -52.4 275 78 40 7.3 4.0
29000 -44.4 -47.9 290 69 35 7.6 4.2 | -44.8 -48.6 280 75 39 7.2 3.9
28000 -42.1 -43.8 290 68 35 7.6 4.2 | -42.6 -44.7 280 73 38 7.2 3.9
27000 -39.9 -39.8 290 67 35 7.6 4.2 | -39.9 -39.8 280 71 36 7.4 4.1
26000 -37.5 -35.5 295 65 34 7.8 4.3 | -37.5 -35.5 280 69 35 8.1 4.4
25000 -35.2 -31.4 295 63 33 7.8 4.3 | -35.1 -31.2 280 67 35 8.1 4.4
24000 -32.9 -27.2 295 61 31 7.9 4.3 | -32.7 -26.9 280 65 34 8.0 4.4
23000 -30.7 -23.3 295 58 30 7.2 3.9 | -30.4 -22.7 280 63 33 7.4 4.1
22000 -28.5 -19.3 295 55 28 7.2 4.0 | -28.2 -18.8 280 61 32 7.4 4.1
21000 -25.9 -14.6 295 52 27 7.4 4.1 | -26.0 -14.8 280 59 31 7.4 4.1
20000 -23.6 -10.5 290 49 25 7.4 4.1 | -23.8 -10.8 280 56 29 7.4 4.1
19500 -22.5 -8.5 290 47 24 7.4 4.1 | -22.7 -8.9 280 55 28 7.4 4.1
19000 -21.4 -6.5 285 46 24 7.4 4.1 | -21.6 -6.9 280 53 28 7.4 4.1
18500 -20.3 -4.5 285 45 23 7.6 4.2 | -20.5 -4.9 280 52 27 7.5 4.1
18000 -19.2 -2.6 285 44 22 7.7 4.2 | -19.4 -2.9 280 51 26 7.6 4.2
17500 -18.0 -0.4 285 42 22 7.6 4.2 | -18.2 -0.8 280 50 26 7.7 4.2
17000 -16.9 1.6 280 41 21 7.4 4.0 | -17.1 1.2 280 49 25 7.4 4.1
16500 -15.8 3.6 280 40 21 7.4 4.1 | -16.0 3.2 275 48 25 7.4 4.1
16000 -14.7 5.5 280 39 20 7.2 4.0 | -14.9 5.2 275 47 24 7.2 4.0
15500 -13.7 7.3 280 38 19 7.2 4.0 | -13.9 7.0 275 46 24 7.2 3.9
15000 -12.6 9.3 280 36 19 6.8 3.8 | -12.8 9.0 275 45 23 7.1 3.9
14500 -11.6 11.1 280 35 18 6.7 3.7 | -11.8 10.8 275 43 22 7.0 3.8
14000 -10.6 12.9 280 33 17 6.4 3.5 | -10.7 12.7 275 42 22 7.0 3.8
13500 -9.7 14.5 275 32 16 6.1 3.4 | -9.7 14.5 270 41 21 6.9 3.8
13000 -8.8 16.2 275 30 15 5.7 3.1 | -8.7 16.3 270 39 20 6.7 3.7
12500 -8.1 17.4 275 28 14 4.8 2.6 | -7.8 18.0 265 37 19 5.1 2.8
12000 -7.4 18.7 270 26 13 4.2 2.3 | -7.0 19.4 265 36 18 5.0 2.8
11500 -6.9 19.6 270 24 12 2.3 1.3 | -6.5 20.3 260 33 17 2.3 1.3
11000 -6.6 20.1 265 22 11 1.5 0.8 | -6.1 21.0 255 31 16 2.2 1.2
10500 -6.6 20.1 260 19 10 -0.8 -0.4 | -6.0 21.2 250 28 14 -0.6 -0.3
10250 -6.6 20.1 255 18 9 -0.4 -0.2 | -6.0 21.2 245 26 13 -0.2 -0.1
10000 -6.6 20.1 250 17 9 -1.5 -0.8 | -6.0 21.2 245 24 12 -0.8 -0.5
9750 -6.8 19.8 245 17 9 -2.0 -1.1 | -6.1 21.0 240 24 12 -0.9 -0.5
9500 -6.9 19.6 245 15 8 -1.3 -0.7 | -6.1 21.0 240 22 11 -0.4 -0.2
9250 -7.0 19.4 235 14 7 -1.5 -0.8 | -6.2 20.8 230 18 9 -1.3 -0.7
9000 -7.1 19.2 230 13 7 -1.0 -0.5 | -6.3 20.7 225 16 8 -0.9 -0.5
8750 -7.1 19.2 225 13 6 -0.2 -0.1 | -6.3 20.7 220 15 8 0.4 0.2
8500 -7.1 19.2 220 11 6 -0.1 -0.0 | -6.3 20.7 215 14 7 0.2 0.1
8250 -7.1 19.2 205 10 5 1.2 0.7 | -6.2 20.8 210 12 6 0.7 0.4
8000 -7.0 19.4 200 9 5 0.5 0.3 | -6.2 20.8 205 11 6 1.2 0.6
7750 -7.0 19.4 190 9 5 -0.3 -0.2 | -6.1 21.0 200 10 5 1.4 0.8
7500 -7.0 19.4 185 9 5 1.2 0.7 | -6.0 21.2 195 10 5 1.3 0.7
7250 -6.8 19.8 175 10 5 2.9 1.6 | -5.9 21.4 190 9 5 0.7 0.4
7000 -6.7 19.9 170 10 5 0.1 0.1 | -5.8 21.6 185 9 4 2.3 1.3
6750 -6.8 19.8 165 10 5 -1.4 -0.7 | -5.5 22.1 185 8 4 5.1 2.8
6500 -6.8 19.8 160 9 5 -0.4 -0.2 | -5.1 22.8 180 7 3 6.5 3.5
6250 -6.8 19.8 155 9 4 0.7 0.4 | -4.6 23.7 180 6 3 5.5 3.0
6000 -6.9 19.6 150 8 4 -4.4 -2.4 | -4.1 24.6 175 5 3 9.5 5.2
5750 -7.8 18.0 130 5 2 -21.6 -11.9 | -3.0 26.6 175 4 2 20.0 11.0
5500 -9.7 14.5 095 4 2 -20.8 -11.4 | -1.8 28.8 180 3 2 4.7 2.6
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
01/24/2025 at 1400 MST | 01/24/2025 at 1700 MST
|
CAPE... 0.0 LI... +5.4 | CAPE... 0.0 LI... +5.5
CINH... -0.1 K Index... +2.7 | CINH... 0.0 K Index... +4.6
|
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 -56.0 -68.8 280 51 26 1.0 0.6 | -55.5 -67.9 280 53 28 0.4 0.2
45000 -54.4 -65.9 275 63 33 1.0 0.5 | -54.9 -66.8 275 63 32 0.3 0.2
40000 -59.4 -74.9 275 78 40 -3.7 -2.0 | -59.4 -74.9 275 80 41 -3.3 -1.8
38000 -60.4 -76.7 275 83 43 3.5 1.9 | -60.2 -76.4 270 85 44 3.2 1.7
36000 -58.2 -72.8 270 88 45 3.6 2.0 | -58.2 -72.8 270 89 46 3.3 1.8
34000 -56.0 -68.8 270 92 48 4.9 2.7 | -56.3 -69.3 270 93 48 4.6 2.5
32000 -51.8 -61.2 270 91 47 7.0 3.9 | -52.0 -61.6 265 93 48 7.2 4.0
30000 -47.6 -53.7 270 90 46 7.3 4.0 | -47.7 -53.9 265 94 48 7.5 4.1
29000 -45.4 -49.7 270 87 45 7.5 4.1 | -45.4 -49.7 265 90 47 7.6 4.2
28000 -43.1 -45.6 270 84 43 7.5 4.1 | -43.1 -45.6 265 87 45 7.6 4.2
27000 -40.9 -41.6 270 81 42 7.4 4.1 | -40.9 -41.6 265 84 43 7.6 4.2
26000 -37.9 -36.2 270 79 40 8.0 4.4 | -38.6 -37.5 265 81 42 7.6 4.2
25000 -35.6 -32.1 275 77 40 8.0 4.4 | -36.3 -33.3 270 78 40 7.6 4.2
24000 -33.2 -27.8 275 75 39 8.0 4.4 | -33.4 -28.1 270 75 39 7.7 4.2
23000 -30.9 -23.6 275 72 37 7.7 4.2 | -31.2 -24.2 270 72 37 7.7 4.2
22000 -28.6 -19.5 275 69 36 7.7 4.2 | -28.9 -20.0 270 68 35 7.7 4.2
21000 -26.3 -15.3 275 66 34 7.7 4.2 | -26.6 -15.9 275 65 33 7.6 4.2
20000 -24.0 -11.2 275 63 32 7.7 4.2 | -24.4 -11.9 275 62 32 7.4 4.1
19500 -22.8 -9.0 275 61 31 7.7 4.2 | -23.3 -9.9 275 61 32 7.4 4.1
19000 -21.7 -7.1 270 59 31 7.7 4.2 | -22.2 -8.0 275 60 31 7.4 4.1
18500 -20.5 -4.9 270 58 30 7.7 4.2 | -21.0 -5.8 275 59 31 7.4 4.1
18000 -19.4 -2.9 270 56 29 7.5 4.1 | -20.0 -4.0 275 58 30 7.1 3.9
17500 -18.3 -0.9 270 55 28 7.6 4.2 | -18.9 -2.0 275 57 29 7.2 3.9
17000 -17.2 1.0 270 53 28 7.0 3.8 | -17.9 -0.2 275 56 29 6.3 3.5
16500 -16.2 2.8 270 52 27 7.0 3.8 | -17.0 1.4 275 54 28 6.2 3.4
16000 -15.1 4.8 270 51 26 6.9 3.8 | -16.0 3.2 275 52 27 6.0 3.3
15500 -14.1 6.6 275 50 26 6.9 3.8 | -15.2 4.6 275 50 26 5.7 3.1
15000 -13.1 8.4 275 48 25 6.9 3.8 | -14.4 6.1 275 48 25 5.9 3.2
14500 -12.1 10.2 275 47 24 7.0 3.8 | -13.4 7.9 275 46 24 7.0 3.9
14000 -11.0 12.2 275 46 23 7.0 3.8 | -12.3 9.9 275 44 23 7.0 3.8
13500 -10.0 14.0 275 44 23 6.5 3.5 | -11.3 11.7 275 42 22 7.1 3.9
13000 -9.1 15.6 270 43 22 6.6 3.6 | -10.2 13.6 275 40 20 7.3 4.0
12500 -8.2 17.2 270 41 21 5.2 2.8 | -9.2 15.4 275 38 19 5.9 3.3
12000 -7.4 18.7 265 40 20 5.6 3.1 | -8.3 17.1 275 35 18 6.2 3.4
11500 -6.8 19.8 265 38 19 2.6 1.4 | -7.5 18.5 270 33 17 4.4 2.4
11000 -6.3 20.7 260 35 18 3.0 1.7 | -6.8 19.8 270 30 16 4.7 2.6
10500 -6.0 21.2 255 33 17 1.2 0.7 | -6.2 20.8 265 28 15 2.9 1.6
10250 -5.9 21.4 250 32 16 1.7 0.9 | -6.0 21.2 260 28 14 3.2 1.8
10000 -5.7 21.7 250 31 16 0.5 0.3 | -5.7 21.7 260 27 14 2.7 1.5
9750 -5.7 21.7 245 27 14 -0.1 -0.0 | -5.5 22.1 255 24 12 2.9 1.6
9500 -5.7 21.7 240 25 13 0.6 0.3 | -5.3 22.5 250 22 11 3.5 1.9
9250 -5.7 21.7 240 23 12 0.6 0.3 | -5.0 23.0 245 20 10 3.1 1.7
9000 -5.6 21.9 235 20 10 0.6 0.3 | -4.8 23.4 240 19 10 4.3 2.4
8750 -5.5 22.1 230 17 9 1.5 0.8 | -4.4 24.1 240 19 10 4.1 2.2
8500 -5.4 22.3 225 15 8 1.8 1.0 | -4.0 24.8 230 14 7 3.4 1.9
8250 -5.3 22.5 220 12 6 -1.2 -0.6 | -3.8 25.2 225 11 6 1.3 0.7
8000 -5.4 22.3 220 9 5 2.3 1.2 | -3.7 25.3 225 10 5 2.9 1.6
7750 -4.9 23.2 220 8 4 8.2 4.5 | -3.3 26.1 220 8 4 6.0 3.3
7500 -4.4 24.1 220 6 3 6.1 3.3 | -2.9 26.8 220 6 3 4.8 2.6
7250 -4.0 24.8 225 5 3 2.6 1.4 | -2.6 27.3 215 5 2 2.9 1.6
7000 -3.8 25.2 235 4 2 7.8 4.3 | -2.4 27.7 225 3 2 5.0 2.8
6750 -2.8 27.0 235 4 2 13.7 7.5 | -1.8 28.8 230 2 1 8.2 4.5
6500 -2.0 28.4 240 4 2 9.4 5.2 | -1.2 29.8 250 2 1 6.7 3.7
6250 -1.4 29.5 255 3 2 6.9 3.8 | -0.8 30.6 295 2 1 5.4 3.0
6000 -0.8 30.6 270 3 1 9.7 5.3 | -0.3 31.5 325 2 1 7.5 4.1
5750 0.2 32.4 250 3 2 16.6 9.1 | 0.2 32.4 320 2 1 6.9 3.8
5500 1.6 34.9 280 3 1 19.4 10.6 | -0.1 31.8 330 2 1 -23.5 -12.9
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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