Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
507
UXUS97 KBOU 070120
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1919 MDT Monday, May 6, 2024
This forecast is for Tuesday, May 7, 2024:
If the trigger temperature of 49.2 F/9.5 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 770 ft/min (3.9 m/s)
Maximum height of thermals.................. 16586 ft MSL (11329 ft AGL)
Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 13761 ft MSL (8504 ft AGL)
Thermal soaring outlook for Wednesday 05/08.... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Becoming less of a factor due to
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 26712 ft MSL (21455 ft AGL)
Wave soaring outlook for Wednesday 05/08....... Poor
Remarks...
Sunrise/Sunset.................... 05:51:55 / 20:00:04 MDT
Total possible sunshine........... 14 hr 8 min 9 sec (848 min 9 sec)
Altitude of sun at 12:56:00 MDT... 67.32 degrees
Upper air data from numerical model forecast valid on 05/07/2024 at 0600 MDT
Freezing level.................. 8386 ft MSL (3129 ft AGL)
Convective condensation level... 14616 ft MSL (9359 ft AGL)
Lifted condensation level....... 15690 ft MSL (10433 ft AGL)
Lifted index.................... +2.2
K index......................... -0.8
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 -50.8 -59.4 250 34 17 3.8 2.1 M M M M M
45000 -45.0 -49.0 255 56 29 1.7 0.9 M M M M M
40000 -49.7 -57.5 260 59 30 -3.2 -1.8 M M M M M
38000 -50.5 -58.9 260 62 32 2.9 1.6 M M M M M
36000 -48.7 -55.7 265 70 36 3.0 1.6 M M M M M
34000 -46.9 -52.4 270 78 40 3.0 1.6 M M M M M
32000 -44.8 -48.6 275 80 41 3.1 1.7 M M M M M
30000 -42.9 -45.2 280 81 42 3.9 2.1 M M M M M
29000 -41.5 -42.7 280 83 43 4.8 2.6 32.4 90.3 12.3 M M
28000 -40.0 -40.0 280 84 43 4.8 2.6 30.4 86.7 11.0 M M
27000 -38.6 -37.5 280 86 44 4.9 2.7 28.6 83.4 9.7 M M
26000 -36.9 -34.4 285 87 45 6.3 3.4 27.0 80.5 8.5 M M
25000 -35.0 -31.0 285 85 44 6.3 3.4 25.6 78.0 7.5 M M
24000 -33.1 -27.6 285 84 43 6.3 3.5 24.3 75.8 6.6 M M
23000 -31.2 -24.2 285 81 42 6.8 3.7 23.2 73.7 5.8 M M
22000 -29.2 -20.6 285 77 40 6.8 3.7 22.0 71.6 4.9 M M
21000 -27.1 -16.8 285 74 38 6.8 3.7 21.0 69.8 4.1 M M
20000 -25.1 -13.2 285 70 36 6.7 3.7 19.9 67.9 3.2 M M
19500 -24.1 -11.4 285 69 36 6.7 3.7 19.4 66.9 2.7 M M
19000 -23.1 -9.6 285 68 35 6.7 3.7 18.8 65.9 2.3 M M
18500 -22.1 -7.8 285 66 34 6.8 3.7 18.3 65.0 1.9 M M
18000 -21.1 -6.0 280 65 33 6.7 3.7 17.9 64.2 1.5 M M
17500 -20.1 -4.2 280 64 33 6.7 3.6 17.3 63.2 1.0 M M
17000 -19.1 -2.4 280 64 33 6.6 3.6 16.8 62.2 0.5 M M
16500 -18.1 -0.6 285 63 33 6.1 3.4 16.2 61.2 0.0 M M
16000 -17.2 1.0 285 63 32 6.2 3.4 15.6 60.1 -0.5 929 4.7
15500 -16.3 2.7 285 62 32 6.1 3.3 15.0 59.0 -1.1 887 4.5
15000 -15.4 4.3 285 61 31 6.1 3.3 14.4 57.9 -1.7 845 4.3
14500 -14.0 6.8 285 60 31 7.0 3.8 13.5 56.4 -2.4 780 4.0
14000 -12.9 8.8 285 59 30 6.8 3.7 13.1 55.5 -2.9 734 3.7
13500 -11.8 10.8 285 56 29 8.3 4.6 12.7 54.9 -3.3 686 3.5
13000 -10.6 12.9 285 50 26 8.3 4.5 12.5 54.4 -3.5 634 3.2
12500 -9.4 15.1 280 47 24 8.4 4.6 12.2 54.0 -3.8 583 3.0
12000 -8.1 17.4 280 47 24 8.4 4.6 12.0 53.6 -4.0 530 2.7
11500 -6.9 19.6 280 47 24 7.7 4.2 11.7 53.1 -4.3 480 2.4
11000 -5.8 21.6 280 47 24 7.8 4.3 11.4 52.5 -4.7 431 2.2
10500 -4.8 23.4 280 47 24 5.6 3.1 10.9 51.7 -5.2 386 2.0
10250 -4.4 24.1 280 47 24 5.2 2.8 10.6 51.1 -5.5 367 1.9
10000 -4.0 24.8 280 47 24 7.8 4.3 10.3 50.5 -5.8 347 1.8
9750 -3.3 26.1 280 47 24 8.6 4.7 10.2 50.4 -5.9 319 1.6
9500 -2.8 27.0 275 46 23 7.1 3.9 10.0 50.1 -6.1 296 1.5
9250 -2.2 28.0 275 45 23 6.7 3.7 9.8 49.7 -6.3 273 1.4
9000 -1.7 28.9 275 43 22 9.4 5.1 9.6 49.4 -6.6 249 1.3
8750 -0.9 30.4 275 42 21 10.6 5.8 9.8 49.6 -6.5 217 1.1
8500 -0.2 31.6 275 40 21 8.6 4.7 9.7 49.4 -6.6 190 1.0
8250 0.5 32.9 275 39 20 9.6 5.3 9.6 49.4 -6.6 162 0.8
8000 1.1 34.0 270 38 20 7.5 4.1 9.6 49.3 -6.7 135 0.7
7750 1.6 34.9 270 37 19 7.9 4.3 9.4 48.8 -7.0 112 0.6
7500 2.4 36.3 270 35 18 10.0 5.5 9.3 48.8 -7.0 83 0.4
7250 3.1 37.6 270 33 17 10.0 5.5 9.3 48.8 -7.0 54 0.3
7000 3.8 38.8 270 32 16 6.8 3.7 9.3 48.8 -7.1 26 0.1
6750 4.2 39.6 270 30 16 6.7 3.7 9.0 48.2 -7.4 7 0.0
6500 4.9 40.8 270 28 14 10.4 5.7 8.9 48.1 -7.5 M M
6250 5.6 42.1 270 26 13 7.4 4.1 8.9 48.0 -7.5 M M
6000 5.9 42.6 265 23 12 2.9 1.6 8.5 47.4 -7.9 M M
5750 6.1 43.0 265 20 10 3.9 2.1 8.0 46.4 -8.5 M M
5500 6.4 43.5 260 14 7 3.4 1.9 7.6 45.7 -8.9 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/07/2024 at 0900 MDT | 05/07/2024 at 1200 MDT
|
CAPE... +2.3 LI... +1.7 | CAPE... +99.3 LI... -0.4
CINH... -2.9 K Index... +8.2 | CINH... -1.8 K Index... +17.1
|
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 -51.8 -61.2 240 33 17 3.6 2.0 | -52.0 -61.6 235 33 17 2.7 1.5
45000 -46.4 -51.5 245 58 30 2.4 1.3 | -48.0 -54.4 245 60 31 2.0 1.1
40000 -48.1 -54.6 255 60 31 -1.2 -0.7 | -48.3 -54.9 255 60 31 -0.2 -0.1
38000 -48.3 -54.9 260 62 32 1.6 0.9 | -48.1 -54.6 260 63 32 1.8 1.0
36000 -47.3 -53.1 265 67 35 1.6 0.9 | -47.0 -52.6 265 69 36 1.8 1.0
34000 -46.2 -51.2 270 74 38 2.0 1.1 | -45.7 -50.3 270 77 40 2.1 1.2
32000 -44.7 -48.5 275 82 42 2.6 1.4 | -44.2 -47.6 270 83 43 2.6 1.4
30000 -43.1 -45.6 275 91 47 3.3 1.8 | -42.6 -44.7 270 89 46 3.1 1.7
29000 -41.7 -43.1 275 93 48 4.9 2.7 | -41.4 -42.5 270 90 46 4.3 2.4
28000 -40.2 -40.4 275 95 49 4.9 2.7 | -40.1 -40.2 270 91 47 4.3 2.4
27000 -38.8 -37.8 275 97 50 4.9 2.7 | -38.8 -37.8 270 91 47 4.3 2.4
26000 -37.1 -34.8 275 97 50 6.4 3.5 | -37.3 -35.1 270 91 47 5.8 3.2
25000 -35.2 -31.4 275 94 48 6.4 3.5 | -35.6 -32.1 270 87 45 5.7 3.2
24000 -33.3 -27.9 275 91 47 6.4 3.5 | -33.9 -29.0 270 84 43 5.7 3.2
23000 -31.5 -24.7 275 87 45 4.7 2.6 | -32.2 -26.0 270 80 41 5.2 2.8
22000 -30.1 -22.2 275 79 41 4.8 2.6 | -30.7 -23.3 270 72 37 5.2 2.9
21000 -28.6 -19.5 275 72 37 4.8 2.7 | -29.1 -20.4 270 63 33 5.3 2.9
20000 -26.8 -16.2 275 67 34 7.0 3.8 | -27.1 -16.8 270 57 29 7.8 4.3
19500 -25.8 -14.4 275 65 33 7.1 3.9 | -25.9 -14.6 270 55 28 7.9 4.3
19000 -24.7 -12.5 280 63 33 7.1 3.9 | -24.8 -12.6 265 53 27 7.9 4.3
18500 -23.7 -10.7 280 62 32 7.1 3.9 | -23.6 -10.5 265 50 26 7.9 4.4
18000 -22.6 -8.7 280 60 31 7.6 4.2 | -22.4 -8.3 265 48 25 8.0 4.4
17500 -21.4 -6.5 280 59 30 8.1 4.5 | -21.2 -6.2 265 47 24 8.0 4.4
17000 -19.6 -3.3 280 58 30 7.9 4.3 | -19.4 -2.9 265 46 24 8.0 4.4
16500 -18.4 -1.1 280 58 30 7.7 4.2 | -18.3 -0.9 265 46 24 7.9 4.4
16000 -17.3 0.9 280 58 30 7.8 4.3 | -17.1 1.2 265 46 23 8.0 4.4
15500 -16.1 3.0 280 57 29 7.9 4.3 | -15.9 3.4 265 45 23 8.3 4.5
15000 -15.0 5.0 280 55 28 7.9 4.3 | -14.7 5.5 265 44 23 8.3 4.5
14500 -13.8 7.2 280 54 28 7.8 4.3 | -13.4 7.9 265 44 22 8.4 4.6
14000 -12.6 9.3 280 53 27 7.8 4.3 | -12.2 10.0 265 43 22 8.4 4.6
13500 -11.5 11.3 280 51 26 7.9 4.3 | -10.9 12.4 265 42 22 8.9 4.9
13000 -10.3 13.5 275 49 25 7.9 4.3 | -9.6 14.7 265 41 21 8.9 4.9
12500 -9.1 15.6 275 47 24 7.9 4.4 | -8.3 17.1 265 40 20 8.6 4.7
12000 -7.9 17.8 275 46 24 8.0 4.4 | -7.0 19.4 265 38 20 8.6 4.7
11500 -6.8 19.8 275 45 23 7.7 4.2 | -5.7 21.7 265 37 19 8.7 4.8
11000 -5.6 21.9 275 43 22 7.8 4.3 | -4.4 24.1 265 35 18 8.8 4.8
10500 -4.6 23.7 275 41 21 5.5 3.0 | -3.2 26.2 265 33 17 7.1 3.9
10250 -4.2 24.4 275 40 21 5.0 2.8 | -2.7 27.1 265 32 16 7.5 4.1
10000 -3.8 25.2 275 39 20 9.1 5.0 | -2.0 28.4 265 31 16 11.4 6.3
9750 -3.0 26.6 275 38 19 9.8 5.4 | -1.1 30.0 265 30 16 11.4 6.3
9500 -2.4 27.7 270 36 18 6.9 3.8 | -0.3 31.5 265 30 15 8.9 4.9
9250 -1.9 28.6 270 34 18 6.6 3.6 | 0.3 32.5 265 29 15 8.5 4.7
9000 -1.4 29.5 270 32 17 9.1 5.0 | 1.0 33.8 265 28 14 10.5 5.8
8750 -0.6 30.9 270 31 16 10.3 5.6 | 1.8 35.2 265 28 14 10.6 5.8
8500 0.1 32.2 270 30 15 8.5 4.7 | 2.5 36.5 265 27 14 8.9 4.9
8250 0.7 33.3 270 29 15 9.4 5.1 | 3.2 37.8 265 27 14 8.8 4.8
8000 1.4 34.5 270 27 14 7.7 4.2 | 3.9 39.0 265 26 13 10.9 6.0
7750 1.9 35.4 265 26 13 8.7 4.8 | 4.8 40.6 270 26 13 11.4 6.3
7500 2.7 36.9 265 25 13 10.5 5.8 | 5.6 42.1 270 25 13 9.2 5.1
7250 3.5 38.3 265 24 12 11.3 6.2 | 6.3 43.3 270 25 13 10.7 5.9
7000 4.3 39.7 265 23 12 6.3 3.5 | 7.0 44.6 270 24 12 6.9 3.8
6750 4.6 40.3 265 22 11 7.2 4.0 | 7.5 45.5 270 24 12 8.5 4.6
6500 5.5 41.9 265 21 11 13.5 7.4 | 8.4 47.1 270 23 12 13.2 7.3
6250 6.4 43.5 265 20 10 10.9 6.0 | 9.3 48.7 270 22 11 11.9 6.5
6000 7.1 44.8 265 19 10 8.6 4.7 | 10.1 50.2 270 21 11 8.7 4.8
5750 7.7 45.9 265 18 9 8.5 4.7 | 10.8 51.4 270 21 11 14.6 8.0
5500 8.6 47.5 265 16 8 15.2 8.4 | 12.6 54.7 270 18 9 31.9 17.5
05/07/2024 at 1500 MDT | 05/07/2024 at 1800 MDT
|
CAPE... +98.7 LI... -0.5 | CAPE... +38.8 LI... +0.9
CINH... -1.9 K Index... +18.5 | CINH... -8.0 K Index... +7.5
|
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 -52.4 -62.3 235 36 18 2.7 1.5 | -52.0 -61.6 240 34 17 2.5 1.4
45000 -48.3 -54.9 245 61 32 2.2 1.2 | -48.3 -54.9 245 60 31 1.6 0.9
40000 -49.7 -57.5 260 64 33 -1.0 -0.5 | -49.7 -57.5 255 61 31 -1.0 -0.5
38000 -49.3 -56.7 265 67 34 2.9 1.6 | -49.7 -57.5 260 64 33 2.1 1.1
36000 -47.6 -53.7 270 71 37 2.9 1.6 | -48.4 -55.1 265 70 36 2.1 1.2
34000 -45.9 -50.6 275 76 39 3.2 1.7 | -47.0 -52.6 270 77 40 3.5 1.9
32000 -43.7 -46.7 275 82 42 3.8 2.1 | -44.3 -47.7 270 82 42 4.4 2.4
30000 -41.4 -42.5 270 89 46 3.8 2.1 | -41.6 -42.9 270 87 45 4.2 2.3
29000 -40.4 -40.7 270 89 46 3.3 1.8 | -40.4 -40.7 270 86 44 3.9 2.1
28000 -39.4 -38.9 270 88 45 3.3 1.8 | -39.3 -38.7 270 85 44 3.9 2.1
27000 -38.4 -37.1 270 88 45 3.3 1.8 | -38.1 -36.6 270 84 43 4.0 2.2
26000 -37.2 -35.0 270 87 45 5.6 3.1 | -36.6 -33.9 270 82 42 6.0 3.3
25000 -35.2 -31.4 270 84 43 5.4 3.0 | -34.8 -30.6 265 80 41 6.1 3.3
24000 -33.6 -28.5 270 81 42 5.5 3.0 | -33.0 -27.4 265 78 40 6.1 3.3
23000 -31.8 -25.2 270 75 39 6.6 3.6 | -31.1 -24.0 265 75 39 7.0 3.8
22000 -29.9 -21.8 265 64 33 6.6 3.6 | -29.0 -20.2 265 72 37 6.9 3.8
21000 -27.9 -18.2 265 53 27 6.6 3.6 | -26.9 -16.4 260 68 35 7.0 3.8
20000 -25.8 -14.4 260 49 25 7.1 3.9 | -25.1 -13.2 260 61 32 5.5 3.0
19500 -24.8 -12.6 260 49 25 7.1 3.9 | -24.3 -11.7 260 57 30 5.5 3.0
19000 -23.7 -10.7 260 50 26 7.1 3.9 | -23.4 -10.1 255 54 28 5.5 3.0
18500 -22.7 -8.9 260 50 26 7.1 3.9 | -22.6 -8.7 255 50 26 5.6 3.1
18000 -21.6 -6.9 255 50 26 7.7 4.2 | -21.8 -7.2 255 46 24 6.8 3.8
17500 -20.4 -4.7 255 49 25 7.9 4.4 | -20.6 -5.1 255 47 24 7.8 4.3
17000 -19.3 -2.7 255 48 25 8.0 4.4 | -19.4 -2.9 255 49 25 7.9 4.3
16500 -18.1 -0.6 255 46 24 8.1 4.4 | -17.8 -0.0 255 49 25 7.4 4.1
16000 -16.9 1.6 255 44 23 8.1 4.4 | -16.7 1.9 255 50 26 7.6 4.2
15500 -15.7 3.7 250 42 22 8.3 4.5 | -15.5 4.1 255 49 25 8.2 4.5
15000 -14.5 5.9 250 40 21 8.2 4.5 | -14.3 6.3 255 48 25 8.2 4.5
14500 -13.3 8.1 255 38 20 8.8 4.8 | -13.1 8.4 255 46 24 7.6 4.1
14000 -12.0 10.4 255 37 19 8.9 4.9 | -12.0 10.4 255 44 23 7.6 4.1
13500 -10.7 12.7 255 35 18 9.0 4.9 | -10.8 12.6 255 42 22 8.3 4.6
13000 -9.3 15.3 255 34 17 9.0 4.9 | -9.6 14.7 260 41 21 8.3 4.6
12500 -8.0 17.6 255 32 17 9.2 5.1 | -8.3 17.1 260 39 20 8.4 4.6
12000 -5.9 21.4 255 31 16 9.5 5.2 | -7.1 19.2 260 38 19 8.4 4.6
11500 -4.5 23.9 260 30 15 9.2 5.0 | -5.8 21.6 265 36 19 8.5 4.7
11000 -3.1 26.4 260 28 15 9.3 5.1 | -4.6 23.7 265 35 18 8.6 4.7
10500 -1.9 28.6 265 27 14 6.9 3.8 | -3.3 26.1 265 34 18 7.7 4.2
10250 -1.3 29.7 265 27 14 8.1 4.4 | -2.8 27.0 270 34 18 7.8 4.3
10000 -0.6 30.9 270 26 13 11.3 6.2 | -2.1 28.2 270 34 18 10.8 5.9
9750 0.2 32.4 270 25 13 10.3 5.6 | -1.2 29.8 270 34 18 10.5 5.7
9500 0.9 33.6 275 25 13 8.4 4.6 | -0.6 30.9 270 34 17 8.1 4.4
9250 1.5 34.7 275 24 13 8.1 4.5 | 0.0 32.0 275 33 17 8.0 4.4
9000 2.2 36.0 275 24 12 10.4 5.7 | 0.6 33.1 275 33 17 9.1 5.0
8750 3.0 37.4 280 24 12 10.8 5.9 | 1.3 34.3 275 33 17 9.7 5.3
8500 3.7 38.7 280 24 12 8.7 4.8 | 2.0 35.6 275 32 16 8.8 4.8
8250 4.4 39.9 280 24 12 8.7 4.8 | 2.7 36.9 280 31 16 9.4 5.2
8000 5.1 41.2 280 23 12 10.6 5.8 | 3.3 37.9 280 31 16 7.8 4.3
7750 5.9 42.6 285 23 12 11.4 6.3 | 3.9 39.0 280 30 15 8.3 4.6
7500 6.7 44.1 285 23 12 9.6 5.3 | 4.6 40.3 285 29 15 10.1 5.5
7250 7.4 45.3 285 23 12 10.9 6.0 | 5.3 41.5 285 29 15 10.1 5.6
7000 8.2 46.8 285 23 12 7.6 4.2 | 6.1 43.0 285 28 14 8.2 4.5
6750 8.7 47.7 285 23 12 8.7 4.8 | 6.6 43.9 285 27 14 8.9 4.9
6500 9.6 49.3 285 22 11 12.7 7.0 | 7.5 45.5 290 27 14 11.6 6.3
6250 10.4 50.7 290 22 11 11.4 6.3 | 8.3 46.9 290 26 13 10.6 5.8
6000 11.2 52.2 290 21 11 7.4 4.1 | 9.0 48.2 290 25 13 9.4 5.1
5750 11.8 53.2 290 20 10 13.5 7.4 | 9.7 49.5 290 24 12 9.6 5.3
5500 13.5 56.3 290 18 9 32.1 17.6 | 10.6 51.1 290 21 11 15.5 8.5
________________________________________________________________________________
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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