Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
803
UXUS97 KBOU 221245
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0542 MST Wednesday, January 22, 2025
This forecast is for Wednesday, January 22, 2025:
If the trigger temperature of 33.1 F/0.6 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 151 ft/min (0.8 m/s)
Maximum height of thermals.................. 8067 ft MSL (2777 ft AGL)
Forecast maximum temperature................... 32.0 F/0.5 C
Time of trigger temperature.................... 1415 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................. 6221 ft MSL (931 ft AGL)
Thermal soaring outlook for Thursday 01/23..... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST).........
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 29422 ft MSL (24132 ft AGL)
Wave soaring outlook for Thursday 01/23........ Poor
Remarks...
Sunrise/Sunset.................... 07:14:54 / 17:07:30 MST
Total possible sunshine........... 9 hr 52 min 36 sec (592 min 36 sec)
Altitude of sun at 12:11:12 MST... 30.69 degrees
Upper air data from numerical model forecast valid on 01/22/2025 at 0500 MST
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 14329 ft MSL (9039 ft AGL)
Lifted condensation level....... 12933 ft MSL (7643 ft AGL)
Lifted index.................... +10.5
K index......................... -4.8
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 -54.9 -66.8 305 35 18 1.1 0.6 M M M M M
45000 -53.1 -63.6 300 55 28 1.1 0.6 M M M M M
40000 -51.6 -60.9 295 48 25 0.9 0.5 M M M M M
38000 -51.0 -59.8 295 44 23 1.5 0.8 M M M M M
36000 -50.1 -58.2 295 57 30 1.6 0.9 M M M M M
34000 -49.1 -56.4 300 70 36 1.6 0.9 M M M M M
32000 -48.1 -54.6 295 78 40 1.3 0.7 M M M M M
30000 -47.3 -53.1 295 81 42 1.4 0.8 M M M M M
29000 -46.6 -51.9 295 82 42 3.2 1.8 28.6 83.5 21.5 M M
28000 -45.7 -50.3 295 83 43 3.3 1.8 25.9 78.6 19.7 M M
27000 -44.7 -48.5 295 83 43 3.3 1.8 23.4 74.2 18.0 M M
26000 -43.7 -46.7 300 83 43 3.9 2.1 21.1 70.0 16.4 M M
25000 -42.4 -44.3 300 80 41 4.1 2.3 18.8 65.9 14.9 M M
24000 -41.2 -42.2 305 77 40 4.1 2.3 16.7 62.1 13.4 M M
23000 -39.9 -39.8 305 74 38 4.1 2.3 14.7 58.5 11.9 M M
22000 -38.7 -37.7 305 67 35 4.1 2.3 12.6 54.6 10.3 M M
21000 -37.5 -35.5 305 61 31 4.2 2.3 10.5 51.0 8.7 M M
20000 -35.9 -32.6 310 56 29 7.3 4.0 9.0 48.1 7.5 M M
19500 -34.8 -30.6 310 56 29 7.2 3.9 8.5 47.2 7.1 M M
19000 -33.8 -28.8 310 56 29 7.1 3.9 8.0 46.4 6.8 M M
18500 -32.7 -26.9 310 56 29 7.2 3.9 7.6 45.6 6.5 M M
18000 -31.6 -24.9 315 55 29 7.6 4.2 7.2 44.9 6.1 M M
17500 -30.3 -22.5 310 54 28 8.9 4.9 6.9 44.5 6.0 M M
17000 -29.0 -20.2 310 53 27 9.1 5.0 6.8 44.2 5.9 M M
16500 -27.9 -18.2 310 53 27 6.3 3.5 6.4 43.6 5.6 M M
16000 -26.4 -15.5 310 51 26 6.5 3.6 5.6 42.1 4.9 M M
15500 -25.5 -13.9 305 50 26 6.0 3.3 5.0 41.0 4.4 M M
15000 -24.6 -12.3 305 49 25 6.1 3.4 4.4 39.9 3.9 M M
14500 -23.5 -10.3 305 47 24 7.7 4.2 3.9 39.1 3.5 M M
14000 -22.4 -8.3 305 45 23 7.6 4.2 3.6 38.4 3.2 M M
13500 -21.2 -6.2 305 42 22 8.1 4.4 3.3 37.9 2.9 M M
13000 -20.0 -4.0 305 39 20 8.0 4.4 3.0 37.4 2.6 M M
12500 -18.8 -1.8 310 35 18 8.7 4.8 2.8 37.0 2.4 M M
12000 -17.5 0.5 315 32 17 8.6 4.7 2.6 36.6 2.3 M M
11500 -16.4 2.5 320 31 16 6.5 3.5 2.2 35.9 1.9 M M
11000 -15.4 4.3 330 31 16 6.8 3.8 1.7 35.0 1.5 M M
10500 -14.2 6.4 330 35 18 8.2 4.5 1.4 34.5 1.2 M M
10250 -13.6 7.5 330 37 19 9.3 5.1 1.3 34.3 1.1 M M
10000 -13.0 8.6 330 39 20 4.9 2.7 1.2 34.1 1.0 M M
9750 -12.7 9.1 330 40 20 6.2 3.4 0.7 33.2 0.5 M M
9500 -12.0 10.4 330 40 21 11.5 6.3 0.7 33.3 0.5 M M
9250 -11.2 11.8 330 41 21 10.3 5.7 0.8 33.4 0.6 M M
9000 -10.5 13.1 330 41 21 7.4 4.1 0.8 33.4 0.6 M M
8750 -10.0 14.0 325 41 21 6.8 3.7 0.5 32.8 0.3 M M
8500 -9.3 15.3 325 42 21 10.0 5.5 0.4 32.7 0.2 M M
8250 -8.6 16.5 320 42 22 7.8 4.3 0.4 32.7 0.2 M M
8000 -8.2 17.2 315 42 22 5.1 2.8 0.1 32.1 -0.1 145 0.7
7750 -7.8 18.0 315 42 22 4.4 2.4 -0.3 31.4 -0.5 127 0.6
7500 -7.5 18.5 310 42 21 4.2 2.3 -0.7 30.7 -0.9 110 0.6
7250 -7.2 19.0 305 41 21 4.5 2.5 -1.2 29.9 -1.3 93 0.5
7000 -6.9 19.6 305 39 20 5.0 2.7 -1.5 29.2 -1.7 75 0.4
6750 -6.5 20.3 300 36 19 4.1 2.2 -1.9 28.6 -2.1 57 0.3
6500 -6.2 20.8 300 34 17 4.2 2.3 -2.4 27.7 -2.5 42 0.2
6250 -5.9 21.4 300 30 15 4.8 2.6 -2.8 27.0 -2.9 24 0.1
6000 -5.5 22.1 300 26 14 5.8 3.2 -3.1 26.4 -3.3 6 0.0
5750 -5.2 22.6 300 23 12 1.2 0.7 -3.5 25.7 -3.7 M M
5500 -5.6 21.9 300 17 9 -11.6 -6.4 -4.6 23.7 -4.8 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
01/22/2025 at 0800 MST | 01/22/2025 at 1100 MST
|
CAPE... 0.0 LI... +4.1 | CAPE... 0.0 LI... +4.0
CINH... 0.0 K Index... -2.0 | CINH... 0.0 K Index... +3.1
|
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 -53.0 -63.4 305 43 22 1.3 0.7 | -53.8 -64.8 305 42 22 1.3 0.7
45000 -51.0 -59.8 300 53 28 1.3 0.7 | -51.8 -61.2 305 53 27 1.3 0.7
40000 -49.7 -57.5 290 48 25 0.8 0.5 | -48.7 -55.7 300 50 26 2.2 1.2
38000 -49.2 -56.6 285 46 24 0.9 0.5 | -47.3 -53.1 300 48 25 1.1 0.6
36000 -48.6 -55.5 295 54 28 1.0 0.6 | -47.4 -53.3 300 52 27 -0.0 -0.0
34000 -48.0 -54.4 300 63 33 1.0 0.6 | -47.4 -53.3 300 56 29 -0.0 -0.0
32000 -47.4 -53.3 300 69 36 0.6 0.4 | -46.9 -52.4 300 59 30 1.2 0.7
30000 -47.0 -52.6 295 72 37 0.7 0.4 | -46.2 -51.2 300 62 32 1.2 0.7
29000 -46.7 -52.1 295 72 37 2.0 1.1 | -45.7 -50.3 300 63 32 2.2 1.2
28000 -46.1 -51.0 295 71 37 2.0 1.1 | -45.1 -49.2 300 62 32 2.2 1.2
27000 -45.5 -49.9 295 70 36 2.0 1.1 | -44.4 -47.9 300 62 32 2.1 1.2
26000 -44.9 -48.8 295 69 36 1.9 1.0 | -43.8 -46.8 300 62 32 1.6 0.9
25000 -44.4 -47.9 300 65 34 1.7 0.9 | -43.8 -46.8 300 56 29 -0.2 -0.1
24000 -43.9 -47.0 305 61 31 1.7 0.9 | -43.8 -46.8 295 50 26 -0.2 -0.1
23000 -43.4 -46.1 310 57 29 3.8 2.1 | -43.9 -47.0 295 44 22 1.4 0.8
22000 -41.5 -42.7 310 55 28 6.5 3.5 | -42.3 -44.1 295 40 20 5.7 3.1
21000 -39.6 -39.3 310 53 27 6.5 3.5 | -40.6 -41.1 300 36 19 5.7 3.1
20000 -37.6 -35.7 310 51 26 6.6 3.6 | -38.9 -38.0 305 34 17 6.8 3.8
19500 -36.6 -33.9 310 50 25 6.6 3.6 | -37.9 -36.2 310 33 17 6.7 3.7
19000 -35.6 -32.1 310 48 25 6.6 3.6 | -36.8 -34.2 310 33 17 6.7 3.7
18500 -34.6 -30.3 310 47 24 6.7 3.7 | -35.8 -32.4 310 33 17 6.7 3.7
18000 -33.6 -28.5 310 46 24 7.1 3.9 | -34.8 -30.6 310 33 17 6.7 3.7
17500 -32.3 -26.1 305 46 24 9.5 5.2 | -33.3 -27.9 315 32 16 7.0 3.8
17000 -30.2 -22.4 310 47 24 8.6 4.7 | -32.2 -26.0 325 31 16 6.8 3.7
16500 -29.1 -20.4 310 45 23 7.8 4.3 | -31.3 -24.3 325 30 16 6.3 3.5
16000 -27.9 -18.2 305 43 22 7.6 4.2 | -30.3 -22.5 325 29 15 6.4 3.5
15500 -26.8 -16.2 310 41 21 7.0 3.8 | -29.3 -20.7 325 29 15 7.5 4.1
15000 -25.8 -14.4 310 40 21 7.0 3.9 | -28.2 -18.8 325 28 14 7.4 4.1
14500 -24.8 -12.6 315 39 20 6.1 3.4 | -27.1 -16.8 325 27 14 6.8 3.7
14000 -23.9 -11.0 315 38 20 6.2 3.4 | -26.1 -15.0 325 25 13 6.8 3.8
13500 -23.0 -9.4 315 36 19 6.0 3.3 | -25.0 -13.0 325 24 12 7.0 3.8
13000 -22.1 -7.8 315 34 17 6.0 3.3 | -24.0 -11.2 325 22 12 6.9 3.8
12500 -21.3 -6.3 320 31 16 5.4 3.0 | -22.9 -9.2 325 21 11 7.5 4.1
12000 -20.5 -4.9 320 28 14 5.5 3.0 | -21.8 -7.2 325 20 10 7.5 4.1
11500 -19.4 -2.9 325 26 13 8.0 4.4 | -20.6 -5.1 325 18 9 8.7 4.8
11000 -18.3 -0.9 330 24 13 7.6 4.2 | -19.3 -2.7 325 17 9 8.4 4.6
10500 -17.2 1.0 340 24 12 6.6 3.6 | -18.1 -0.6 330 16 8 7.4 4.1
10250 -16.7 1.9 340 24 12 7.7 4.2 | -17.6 0.3 330 16 8 8.6 4.7
10000 -16.2 2.8 345 24 13 3.7 2.0 | -17.0 1.4 335 16 8 4.4 2.4
9750 -16.0 3.2 345 25 13 7.1 3.9 | -16.8 1.8 335 15 8 5.9 3.2
9500 -15.0 5.0 345 26 13 13.9 7.6 | -16.0 3.2 335 15 8 11.9 6.5
9250 -14.1 6.6 345 27 14 12.0 6.6 | -15.2 4.6 340 14 7 10.5 5.8
9000 -13.3 8.1 345 27 14 8.6 4.7 | -14.4 6.1 340 14 7 8.4 4.6
8750 -12.7 9.1 345 27 14 8.3 4.6 | -13.8 7.2 340 14 7 8.8 4.8
8500 -11.9 10.6 340 27 14 12.3 6.7 | -13.0 8.6 340 15 8 11.6 6.3
8250 -11.0 12.2 340 27 14 10.2 5.6 | -12.2 10.0 340 15 8 10.6 5.8
8000 -10.4 13.3 335 26 14 7.8 4.3 | -11.4 11.5 340 15 8 9.6 5.3
7750 -9.8 14.4 330 26 13 8.0 4.4 | -10.7 12.7 340 15 7 9.8 5.4
7500 -9.2 15.4 325 26 13 7.1 3.9 | -10.0 14.0 340 14 7 9.0 4.9
7250 -8.7 16.3 325 26 13 5.9 3.2 | -9.4 15.1 340 14 7 8.4 4.6
7000 -8.3 17.1 320 25 13 5.3 2.9 | -8.7 16.3 335 13 7 8.0 4.4
6750 -7.9 17.8 320 24 12 6.0 3.3 | -8.1 17.4 335 13 7 9.0 4.9
6500 -7.4 18.7 320 23 12 6.4 3.5 | -7.4 18.7 330 12 6 8.3 4.6
6250 -7.0 19.4 320 21 11 5.8 3.2 | -6.9 19.6 330 10 5 6.9 3.8
6000 -6.5 20.3 320 19 10 6.9 3.8 | -6.4 20.5 325 8 4 7.5 4.1
5750 -6.2 20.8 320 17 9 -0.5 -0.3 | -5.7 21.7 320 6 3 11.1 6.1
5500 -6.8 19.8 315 10 5 -14.8 -8.1 | -4.7 23.5 320 6 3 16.7 9.2
01/22/2025 at 1400 MST | 01/22/2025 at 1700 MST
|
CAPE... 0.0 LI... +1.3 | CAPE... 0.0 LI... +1.5
CINH... -0.1 K Index... +0.1 | CINH... 0.0 K Index... -0.1
|
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 -53.2 -63.8 295 43 22 1.7 0.9 | -53.6 -64.5 305 41 21 1.1 0.6
45000 -50.7 -59.3 300 56 29 1.7 0.9 | -51.9 -61.4 305 44 23 1.1 0.6
40000 -49.1 -56.4 305 50 26 0.9 0.5 | -49.3 -56.7 305 47 24 1.9 1.0
38000 -48.6 -55.5 310 47 24 0.8 0.4 | -48.2 -54.8 305 48 25 0.3 0.2
36000 -48.2 -54.8 310 49 25 0.7 0.4 | -48.9 -56.0 315 47 24 -1.2 -0.6
34000 -47.7 -53.9 315 52 27 0.7 0.4 | -49.7 -57.5 325 47 24 -1.1 -0.6
32000 -46.4 -51.5 315 53 27 2.9 1.6 | -48.9 -56.0 335 48 25 2.3 1.3
30000 -44.7 -48.5 310 54 28 2.9 1.6 | -47.5 -53.5 340 48 25 2.3 1.3
29000 -44.0 -47.2 310 53 27 1.0 0.5 | -46.7 -52.1 345 48 25 3.7 2.0
28000 -43.6 -46.5 310 51 26 1.1 0.6 | -45.6 -50.1 350 47 24 3.7 2.0
27000 -43.3 -45.9 315 49 25 1.1 0.6 | -44.5 -48.1 355 47 24 3.7 2.0
26000 -43.0 -45.4 315 47 24 0.8 0.4 | -43.4 -46.1 360 47 24 3.9 2.1
25000 -43.3 -45.9 315 45 23 -1.3 -0.7 | -42.1 -43.8 005 47 24 4.2 2.3
24000 -43.7 -46.7 315 44 23 -1.3 -0.7 | -40.9 -41.6 010 47 24 4.2 2.3
23000 -44.1 -47.4 320 43 22 -0.5 -0.3 | -39.6 -39.3 015 48 24 2.7 1.5
22000 -43.3 -45.9 315 38 20 3.0 1.7 | -39.4 -38.9 005 44 23 0.4 0.2
21000 -42.4 -44.3 305 33 17 3.0 1.6 | -39.3 -38.7 360 42 22 0.4 0.2
20000 -41.2 -42.2 305 30 15 7.8 4.3 | -38.9 -38.0 350 40 20 4.6 2.5
19500 -40.1 -40.2 310 30 16 7.3 4.0 | -38.2 -36.8 345 38 19 4.2 2.3
19000 -39.0 -38.2 315 31 16 7.3 4.0 | -37.6 -35.7 340 36 19 4.2 2.3
18500 -37.9 -36.2 320 31 16 7.3 4.0 | -37.0 -34.6 335 35 18 4.2 2.3
18000 -36.8 -34.2 320 32 17 7.3 4.0 | -36.4 -33.5 330 34 18 4.5 2.5
17500 -35.7 -32.3 325 33 17 7.4 4.0 | -35.5 -31.9 325 34 17 6.5 3.6
17000 -34.1 -29.4 330 34 17 8.0 4.4 | -34.0 -29.2 320 34 17 7.5 4.1
16500 -32.8 -27.0 335 34 17 8.9 4.9 | -32.8 -27.0 320 34 17 8.7 4.8
16000 -31.4 -24.5 335 34 17 8.8 4.8 | -31.5 -24.7 320 33 17 8.7 4.8
15500 -30.2 -22.4 340 34 17 8.1 4.5 | -30.2 -22.4 320 33 17 8.5 4.7
15000 -28.9 -20.0 340 34 18 8.2 4.5 | -28.9 -20.0 320 32 17 8.6 4.7
14500 -27.7 -17.9 340 34 18 8.8 4.8 | -27.6 -17.7 320 32 16 8.9 4.9
14000 -26.4 -15.5 340 34 18 8.7 4.8 | -26.3 -15.3 325 31 16 8.9 4.9
13500 -25.1 -13.2 340 34 17 8.8 4.8 | -25.0 -13.0 325 31 16 8.8 4.8
13000 -23.7 -10.7 335 33 17 8.8 4.8 | -23.6 -10.5 330 31 16 8.8 4.8
12500 -22.4 -8.3 335 31 16 9.1 5.0 | -22.4 -8.3 330 30 16 8.6 4.7
12000 -21.0 -5.8 335 29 15 9.1 5.0 | -21.1 -6.0 330 28 15 8.5 4.7
11500 -19.7 -3.5 330 27 14 8.8 4.9 | -19.9 -3.8 330 26 14 7.9 4.3
11000 -18.4 -1.1 330 24 12 8.7 4.8 | -18.7 -1.7 330 24 12 8.2 4.5
10500 -17.1 1.2 330 22 11 8.0 4.4 | -17.4 0.7 330 22 11 8.5 4.6
10250 -16.5 2.3 330 21 11 9.1 5.0 | -16.8 1.8 330 21 11 9.2 5.0
10000 -15.9 3.4 330 20 10 4.2 2.3 | -16.2 2.8 330 20 11 3.9 2.1
9750 -15.7 3.7 330 19 10 5.4 3.0 | -16.0 3.2 330 20 10 5.3 2.9
9500 -15.0 5.0 330 18 9 11.6 6.3 | -15.3 4.5 330 19 10 12.1 6.7
9250 -14.2 6.4 330 16 8 9.6 5.2 | -14.4 6.1 330 18 9 9.9 5.5
9000 -13.6 7.5 330 15 8 7.3 4.0 | -13.8 7.2 330 17 9 7.1 3.9
8750 -13.1 8.4 330 14 7 7.6 4.1 | -13.3 8.1 330 16 8 7.9 4.3
8500 -12.4 9.7 335 12 6 9.7 5.3 | -12.6 9.3 325 15 8 10.6 5.8
8250 -11.7 10.9 335 10 5 8.8 4.8 | -11.8 10.8 325 14 7 9.1 5.0
8000 -11.1 12.0 335 9 5 7.5 4.1 | -11.2 11.8 320 14 7 7.7 4.2
7750 -10.5 13.1 335 8 4 8.8 4.8 | -10.6 12.9 320 13 7 8.5 4.7
7500 -9.8 14.4 335 7 4 9.8 5.4 | -10.0 14.0 315 13 6 8.5 4.7
7250 -9.1 15.6 335 7 4 9.6 5.3 | -9.4 15.1 315 12 6 8.2 4.5
7000 -8.4 16.9 335 7 4 9.0 4.9 | -8.8 16.2 310 12 6 7.8 4.3
6750 -7.7 18.1 335 7 3 10.9 6.0 | -8.2 17.2 305 11 6 9.2 5.1
6500 -6.8 19.8 335 7 3 11.2 6.2 | -7.4 18.7 305 11 6 10.1 5.5
6250 -6.1 21.0 335 6 3 9.8 5.4 | -6.7 19.9 300 11 5 9.4 5.1
6000 -5.3 22.5 335 6 3 9.5 5.2 | -6.0 21.2 300 10 5 9.5 5.2
5750 -4.6 23.7 335 6 3 11.2 6.1 | -5.4 22.3 295 9 5 6.2 3.4
5500 -3.6 25.5 335 6 3 16.7 9.2 | -5.1 22.8 290 7 4 1.2 0.6
________________________________________________________________________________
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 near the old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 meters)
and may not be representative of other areas along the Front Range of the
Colorado Rocky Mountains. 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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