Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
192
UXUS97 KGJT 231306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Sunday, February 23, 2025
This forecast is for Sunday, February 23, 2025:
If the trigger temperature of 51.2 F/10.7 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 456 ft/min (2.3 m/s)
Maximum height of thermals.................. 11465 ft MSL (6626 ft AGL)
Forecast maximum temperature................... 59.0 F/15.5 C
Time of trigger temperature.................... 1230 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................. 9392 ft MSL (4553 ft AGL)
Thermal soaring outlook for Monday 02/24....... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:54:22 / 18:00:25 MST
Total possible sunshine........... 11 hr 6 min 3 sec (666 min 3 sec)
Altitude of sun at 12:27:24 MST... 40.94 degrees
Upper air data from rawinsonde observation taken on 02/23/2025 at 0500 MST
Freezing level.................. 8071 ft MSL (3232 ft AGL)
Convective condensation level... 15723 ft MSL (10884 ft AGL)
Lifted condensation level....... 13689 ft MSL (8849 ft AGL)
Lifted index.................... +7.9
K index......................... +1.1
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 -58.5 -73.3 340 50 26 2.9 1.6 103.8 218.8 50.6 M M
45000 -54.8 -66.6 325 53 27 -5.0 -2.7 85.3 185.5 42.8 M M
40000 -55.1 -67.2 325 67 34 -20.8 -11.4 61.5 142.7 30.3 M M
38000 -60.4 -76.7 355 54 28 5.9 3.2 44.6 112.4 19.9 M M
36000 -56.9 -70.4 360 74 38 5.8 3.2 41.1 106.0 18.0 M M
34000 -52.4 -62.3 360 90 46 8.1 4.5 38.1 100.6 16.4 M M
32000 -47.3 -53.1 360 85 44 7.0 3.8 37.1 98.8 16.1 M M
30000 -43.6 -46.5 355 69 35 8.6 4.7 34.1 93.4 14.3 M M
29000 -41.0 -41.8 350 65 33 8.6 4.7 33.7 92.6 14.1 M M
28000 -38.5 -37.3 350 65 33 8.5 4.6 33.2 91.8 13.9 M M
27000 -36.0 -32.8 350 56 29 8.5 4.6 32.7 90.9 13.8 M M
26000 -33.4 -28.1 350 55 28 8.5 4.6 32.2 90.0 13.5 M M
25000 -30.9 -23.6 355 53 27 8.4 4.6 31.7 89.1 13.3 M M
24000 -28.2 -18.8 350 49 25 8.8 4.8 31.3 88.3 13.1 M M
23000 -25.7 -14.3 345 49 25 8.2 4.5 30.8 87.5 12.9 M M
22000 -23.3 -9.9 335 44 23 8.2 4.5 30.2 86.4 12.5 M M
21000 -20.9 -5.6 340 46 24 7.4 4.0 29.6 85.2 12.1 M M
20000 -18.7 -1.7 335 38 20 7.0 3.8 28.7 83.7 11.5 M M
19500 -17.6 0.3 340 37 19 4.7 2.6 28.3 82.9 11.2 M M
19000 -17.7 0.1 330 35 18 -0.2 -0.1 25.7 78.2 9.1 M M
18500 -17.3 0.9 335 37 19 4.2 2.3 24.4 75.9 8.0 M M
18000 -16.4 2.5 325 39 20 8.2 4.5 23.8 74.8 7.4 M M
17500 -15.5 4.1 335 33 17 4.5 2.5 23.1 73.6 6.9 M M
17000 -14.8 5.4 340 28 14 4.6 2.5 22.3 72.1 6.2 M M
16500 -13.8 7.2 340 28 15 8.4 4.6 21.7 71.1 5.8 M M
16000 -12.6 9.3 330 30 15 6.2 3.4 21.4 70.5 5.5 M M
15500 -11.9 10.6 330 29 15 5.1 2.8 20.6 69.1 4.8 M M
15000 -11.2 11.8 325 30 15 5.7 3.1 19.8 67.6 4.1 M M
14500 -10.2 13.6 330 32 16 7.1 3.9 19.3 66.7 3.7 M M
14000 -9.1 15.6 330 31 16 7.1 3.9 18.9 65.9 3.3 M M
13500 -8.0 17.6 330 31 16 7.0 3.8 18.4 65.1 2.9 M M
13000 -7.0 19.4 320 22 11 6.8 3.7 17.9 64.3 2.5 M M
12500 -6.0 21.2 325 24 12 7.6 4.2 17.4 63.4 2.0 M M
12000 -5.5 22.1 335 17 9 -0.6 -0.3 16.4 61.6 1.1 M M
11500 -5.1 22.8 345 16 8 5.7 3.1 15.4 59.7 0.0 M M
11000 -4.5 23.9 350 15 8 3.7 2.0 14.5 58.1 -0.8 424 2.2
10500 -3.7 25.3 345 6 3 5.5 3.0 13.7 56.6 -1.5 387 2.0
10250 -3.2 26.2 355 8 4 7.0 3.8 13.4 56.1 -1.8 365 1.9
10000 -2.6 27.3 350 8 4 8.4 4.6 13.2 55.8 -1.9 339 1.7
9750 -2.1 28.2 355 6 3 4.8 2.7 13.0 55.5 -2.1 316 1.6
9500 -1.9 28.6 360 5 3 2.5 1.4 12.5 54.5 -2.7 304 1.5
9250 -1.8 28.8 345 6 3 3.5 1.9 12.0 53.6 -3.3 292 1.5
9000 -1.6 29.1 315 4 2 3.8 2.1 11.5 52.7 -3.8 278 1.4
8750 -1.2 29.8 300 4 2 3.9 2.1 11.0 51.9 -4.2 261 1.3
8500 -0.9 30.4 285 4 2 4.3 2.4 10.6 51.1 -4.6 244 1.2
8250 -0.5 31.1 275 4 2 6.8 3.7 10.2 50.4 -5.0 224 1.1
8000 0.1 32.2 250 3 2 8.1 4.5 10.1 50.2 -5.1 199 1.0
7750 0.6 33.1 255 3 1 7.8 4.3 10.0 49.9 -5.3 175 0.9
7500 1.2 34.2 255 2 1 7.9 4.3 9.8 49.7 -5.5 151 0.8
7250 1.8 35.2 240 1 1 7.8 4.3 9.7 49.4 -5.7 127 0.6
7000 2.3 36.1 225 2 1 8.2 4.5 9.5 49.1 -5.9 102 0.5
6750 2.8 37.0 175 2 1 4.4 2.4 9.3 48.8 -6.1 80 0.4
6500 3.0 37.4 110 4 2 1.8 1.0 8.7 47.7 -6.7 66 0.3
6250 3.2 37.8 130 7 4 -0.8 -0.4 8.1 46.6 -7.3 55 0.3
6000 3.1 37.6 140 11 6 0.7 0.4 7.2 45.0 -8.1 51 0.3
5750 3.3 37.9 135 11 6 3.5 1.9 6.8 44.2 -8.6 36 0.2
5500 3.5 38.3 125 11 6 6.3 3.5 6.3 43.3 -9.1 21 0.1
5250 3.8 38.8 120 12 6 -7.7 -4.2 5.8 42.5 -9.6 6 0.0
5000 1.9 35.4 120 10 5 -40.6 -22.3 3.2 37.7 -12.3 56 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
02/23/2025 at 0800 MST | 02/23/2025 at 1100 MST
|
CAPE... 0.0 LI... +8.9 | CAPE... 0.0 LI... +9.4
CINH... -0.0 K Index... -0.1 | CINH... 0.0 K Index... -3.0
|
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 -58.1 -72.6 325 42 21 2.5 1.4 | -58.1 -72.6 325 44 23 3.6 1.9
45000 -54.8 -66.6 330 49 25 -3.3 -1.8 | -53.6 -64.5 320 53 27 -4.4 -2.4
40000 -59.2 -74.6 320 50 26 -2.9 -1.6 | -60.4 -76.7 320 51 26 -4.3 -2.4
38000 -58.1 -72.6 335 50 26 4.2 2.3 | -58.9 -74.0 325 47 24 5.4 2.9
36000 -55.6 -68.1 350 54 28 4.2 2.3 | -55.7 -68.3 330 43 22 5.3 2.9
34000 -52.3 -62.1 355 59 30 7.8 4.3 | -51.8 -61.2 335 42 22 8.2 4.5
32000 -47.6 -53.7 350 58 30 7.8 4.3 | -46.9 -52.4 335 43 22 8.2 4.5
30000 -42.7 -44.9 345 57 29 8.8 4.8 | -41.9 -43.4 330 43 22 8.5 4.7
29000 -40.1 -40.2 345 55 29 8.8 4.8 | -39.4 -38.9 330 43 22 8.5 4.7
28000 -37.5 -35.5 340 54 28 8.8 4.8 | -36.8 -34.2 330 42 22 8.5 4.7
27000 -34.9 -30.8 340 52 27 8.3 4.6 | -33.7 -28.7 325 41 21 8.1 4.4
26000 -32.4 -26.3 340 50 26 8.4 4.6 | -31.3 -24.3 325 39 20 8.1 4.4
25000 -29.9 -21.8 340 48 25 8.4 4.6 | -28.9 -20.0 320 37 19 8.1 4.4
24000 -26.8 -16.2 340 45 23 7.7 4.3 | -26.4 -15.5 320 35 18 8.4 4.6
23000 -24.4 -11.9 340 41 21 7.8 4.3 | -23.9 -11.0 320 34 17 8.4 4.6
22000 -22.1 -7.8 340 37 19 7.8 4.3 | -21.4 -6.5 320 32 17 8.4 4.6
21000 -19.8 -3.6 335 34 18 7.3 4.0 | -19.0 -2.2 320 31 16 7.6 4.2
20000 -17.7 0.1 335 33 17 7.3 4.0 | -16.7 1.9 320 30 15 7.6 4.2
19500 -16.6 2.1 335 32 16 7.3 4.0 | -15.5 4.1 320 29 15 7.6 4.2
19000 -15.5 4.1 330 31 16 7.1 3.9 | -14.4 6.1 315 28 15 7.5 4.1
18500 -14.5 5.9 330 31 16 6.1 3.3 | -13.3 8.1 320 28 14 6.8 3.7
18000 -13.6 7.5 330 31 16 6.2 3.4 | -12.3 9.9 320 28 14 6.9 3.8
17500 -12.7 9.1 330 32 16 5.5 3.0 | -11.4 11.5 320 27 14 5.8 3.2
17000 -12.0 10.4 330 32 16 5.4 2.9 | -10.5 13.1 320 27 14 5.6 3.1
16500 -11.2 11.8 330 32 16 5.0 2.7 | -9.7 14.5 320 27 14 5.1 2.8
16000 -10.5 13.1 330 31 16 4.3 2.4 | -9.1 15.6 320 27 14 4.4 2.4
15500 -9.9 14.2 330 30 15 4.3 2.4 | -8.4 16.9 320 26 14 4.4 2.4
15000 -9.3 15.3 330 29 15 3.8 2.1 | -7.8 18.0 320 26 13 4.0 2.2
14500 -8.8 16.2 330 27 14 3.8 2.1 | -7.3 18.9 320 25 13 4.0 2.2
14000 -8.2 17.2 330 25 13 4.5 2.4 | -6.7 19.9 320 24 13 4.3 2.3
13500 -7.5 18.5 330 23 12 4.4 2.4 | -6.0 21.2 320 23 12 4.3 2.3
13000 -6.9 19.6 330 21 11 4.7 2.6 | -5.4 22.3 315 22 11 4.3 2.4
12500 -6.2 20.8 330 19 10 4.7 2.6 | -4.8 23.4 315 20 10 4.4 2.4
12000 -5.5 22.1 330 17 9 4.6 2.5 | -4.1 24.6 315 18 9 4.1 2.2
11500 -4.8 23.4 330 15 7 4.6 2.5 | -3.5 25.7 310 16 8 4.0 2.2
11000 -4.1 24.6 330 12 6 4.5 2.5 | -3.0 26.6 305 14 7 3.8 2.1
10500 -3.5 25.7 330 9 5 4.6 2.5 | -2.4 27.7 300 11 6 3.7 2.0
10250 -3.2 26.2 330 8 4 4.2 2.3 | -2.1 28.2 295 10 5 4.1 2.3
10000 -2.9 26.8 330 6 3 3.8 2.1 | -1.8 28.8 290 9 5 4.2 2.3
9750 -2.6 27.3 330 5 3 4.0 2.2 | -1.5 29.3 285 8 4 3.8 2.1
9500 -2.3 27.9 325 4 2 4.0 2.2 | -1.3 29.7 280 7 3 3.5 1.9
9250 -2.0 28.4 325 3 2 4.4 2.4 | -1.0 30.2 270 5 3 4.5 2.5
9000 -1.6 29.1 330 2 1 4.8 2.7 | -0.6 30.9 255 5 2 5.3 2.9
8750 -1.3 29.7 330 1 0 4.4 2.4 | -0.0 32.0 225 4 2 3.4 1.8
8500 -0.6 30.9 155 1 0 5.0 2.7 | 0.3 32.5 210 4 2 4.6 2.5
8250 -0.2 31.6 150 2 1 5.3 2.9 | 0.6 33.1 200 4 2 5.3 2.9
8000 0.2 32.4 145 2 1 4.8 2.6 | 1.0 33.8 190 4 2 4.5 2.5
7750 0.5 32.9 150 3 1 4.9 2.7 | 1.3 34.3 185 4 2 4.9 2.7
7500 0.9 33.6 150 3 2 5.4 2.9 | 1.7 35.1 175 4 2 6.3 3.4
7250 1.3 34.3 145 3 2 5.7 3.1 | 2.2 36.0 170 4 2 5.3 2.9
7000 1.7 35.1 145 4 2 4.1 2.3 | 2.6 36.7 165 4 2 8.6 4.7
6750 1.9 35.4 145 4 2 3.2 1.8 | 3.4 38.1 165 4 2 10.7 5.9
6500 2.2 36.0 145 4 2 4.1 2.3 | 4.1 39.4 165 4 2 9.6 5.3
6250 2.5 36.5 140 4 2 3.9 2.1 | 4.8 40.6 165 4 2 8.6 4.7
6000 2.6 36.7 140 4 2 -3.0 -1.6 | 5.5 41.9 155 4 2 12.3 6.7
5750 1.9 35.4 135 3 1 -14.4 -7.9 | 6.8 44.2 155 4 2 22.7 12.4
5500 1.2 34.2 110 1 1 5.6 3.1 | 8.2 46.8 150 3 2 3.9 2.2
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
02/23/2025 at 1400 MST | 02/23/2025 at 1700 MST
|
CAPE... 0.0 LI... +8.0 | CAPE... 0.0 LI... +6.4
CINH... -0.1 K Index... +2.9 | CINH... -0.0 K Index... +10.5
|
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 -58.0 -72.4 320 47 24 4.4 2.4 | -58.9 -74.0 320 48 25 4.1 2.3
45000 -52.6 -62.7 320 53 27 -4.3 -2.4 | -53.7 -64.7 310 57 29 -2.7 -1.5
40000 -58.9 -74.0 315 54 28 -4.2 -2.3 | -57.8 -72.0 310 55 28 -2.7 -1.5
38000 -58.0 -72.4 315 52 27 4.4 2.4 | -56.7 -70.1 310 53 27 3.5 1.9
36000 -55.0 -67.0 315 48 25 4.4 2.4 | -54.6 -66.3 305 50 26 3.5 1.9
34000 -51.2 -60.2 315 45 23 8.8 4.8 | -51.0 -59.8 300 49 25 9.1 5.0
32000 -46.0 -50.8 310 42 22 8.7 4.8 | -45.6 -50.1 305 47 24 9.1 5.0
30000 -40.7 -41.3 310 40 21 8.7 4.8 | -40.3 -40.5 305 45 23 8.6 4.7
29000 -38.1 -36.6 315 39 20 8.7 4.8 | -37.7 -35.9 300 43 22 8.6 4.7
28000 -35.5 -31.9 315 38 20 8.7 4.8 | -35.1 -31.2 300 42 22 8.6 4.7
27000 -33.0 -27.4 315 37 19 8.1 4.4 | -32.6 -26.7 300 40 21 7.9 4.3
26000 -30.5 -22.9 310 35 18 8.1 4.5 | -30.3 -22.5 300 39 20 8.0 4.4
25000 -28.1 -18.6 310 33 17 8.1 4.5 | -27.9 -18.2 300 37 19 8.0 4.4
24000 -25.7 -14.3 310 32 16 7.7 4.2 | -25.0 -13.0 295 36 18 7.5 4.1
23000 -22.8 -9.0 305 31 16 7.7 4.2 | -22.7 -8.9 295 35 18 7.5 4.1
22000 -20.5 -4.9 305 30 15 7.7 4.2 | -20.5 -4.9 300 34 18 7.5 4.1
21000 -18.5 -1.3 300 30 15 6.4 3.5 | -18.4 -1.1 300 34 18 6.8 3.7
20000 -16.6 2.1 300 29 15 6.3 3.5 | -16.4 2.5 295 34 18 6.8 3.7
19500 -15.7 3.7 300 29 15 6.3 3.5 | -15.4 4.3 295 34 18 6.8 3.7
19000 -14.7 5.5 300 29 15 6.2 3.4 | -14.4 6.1 295 34 18 6.6 3.6
18500 -13.8 7.2 300 29 15 6.0 3.3 | -13.5 7.7 295 34 18 6.1 3.4
18000 -13.0 8.6 300 28 15 6.0 3.3 | -12.6 9.3 295 34 18 6.2 3.4
17500 -12.1 10.2 300 28 14 6.0 3.3 | -11.7 10.9 295 34 17 6.0 3.3
17000 -11.2 11.8 305 28 14 6.0 3.3 | -10.8 12.6 300 33 17 6.0 3.3
16500 -10.3 13.5 305 28 14 5.9 3.3 | -10.0 14.0 300 33 17 5.8 3.2
16000 -9.4 15.1 305 28 14 5.9 3.2 | -9.2 15.4 300 32 16 5.6 3.1
15500 -8.6 16.5 305 27 14 5.8 3.2 | -8.3 17.1 300 31 16 5.6 3.1
15000 -7.8 18.0 305 27 14 5.4 2.9 | -7.5 18.5 300 30 16 5.4 3.0
14500 -7.0 19.4 305 27 14 5.4 3.0 | -6.7 19.9 300 29 15 5.5 3.0
14000 -6.2 20.8 305 26 13 4.9 2.7 | -6.0 21.2 300 28 15 5.3 2.9
13500 -5.5 22.1 305 25 13 5.0 2.8 | -5.2 22.6 300 27 14 5.3 2.9
13000 -4.8 23.4 305 24 12 4.5 2.5 | -4.4 24.1 300 25 13 5.1 2.8
12500 -4.1 24.6 305 22 12 4.5 2.5 | -3.6 25.5 295 23 12 5.1 2.8
12000 -3.4 25.9 300 21 11 4.2 2.3 | -2.8 27.0 295 21 11 5.1 2.8
11500 -2.8 27.0 295 18 10 4.2 2.3 | -2.0 28.4 290 19 10 5.2 2.8
11000 -2.2 28.0 290 16 8 3.9 2.2 | -1.2 29.8 285 17 9 4.8 2.6
10500 -1.6 29.1 285 14 7 3.7 2.0 | -0.5 31.1 275 15 8 4.6 2.5
10250 -1.3 29.7 280 13 6 5.0 2.8 | -0.2 31.6 270 14 7 5.3 2.9
10000 -0.9 30.4 275 12 6 5.2 2.9 | 0.3 32.5 265 13 7 5.6 3.1
9750 -0.6 30.9 270 11 6 4.2 2.3 | 0.7 33.3 260 12 6 5.2 2.9
9500 -0.3 31.5 265 10 5 3.8 2.1 | 1.0 33.8 255 11 6 4.6 2.5
9250 0.0 32.0 255 8 4 6.4 3.5 | 1.4 34.5 245 10 5 7.4 4.0
9000 0.7 33.3 255 8 4 8.2 4.5 | 2.1 35.8 245 10 5 8.9 4.9
8750 1.2 34.2 250 8 4 5.8 3.2 | 3.1 37.6 240 9 5 5.5 3.0
8500 1.6 34.9 245 7 3 5.6 3.1 | 3.5 38.3 235 8 4 6.4 3.5
8250 2.6 36.7 240 5 3 7.6 4.2 | 4.0 39.2 235 7 4 7.0 3.8
8000 3.1 37.6 235 5 2 7.2 4.0 | 4.5 40.1 235 6 3 6.6 3.6
7750 3.7 38.7 230 4 2 8.1 4.4 | 5.0 41.0 230 5 3 6.8 3.7
7500 4.3 39.7 230 4 2 9.1 5.0 | 5.5 41.9 230 4 2 7.4 4.1
7250 5.0 41.0 230 3 2 8.8 4.8 | 6.0 42.8 230 4 2 7.2 4.0
7000 5.6 42.1 230 3 2 9.7 5.3 | 6.6 43.9 235 3 2 8.9 4.9
6750 6.4 43.5 225 3 2 10.2 5.6 | 7.4 45.3 230 3 2 10.4 5.7
6500 7.1 44.8 225 3 2 9.7 5.3 | 8.1 46.6 235 3 1 9.9 5.5
6250 7.8 46.0 225 3 2 9.8 5.4 | 8.9 48.0 240 2 1 10.2 5.6
6000 8.7 47.7 235 2 1 14.7 8.1 | 9.6 49.3 250 2 1 9.6 5.3
5750 10.1 50.2 240 2 1 22.6 12.4 | 10.3 50.5 250 2 1 9.4 5.1
5500 11.5 52.7 245 2 1 7.8 4.3 | 11.2 52.2 265 2 1 18.4 10.1
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
________________________________________________________________________________
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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