Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
476
UXUS97 KBOU 080033
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1831 MDT Tuesday, May 7, 2024
This forecast is for Wednesday, May 8, 2024:
If the trigger temperature of 44.8 F/7.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1195 ft/min (6.1 m/s)
Maximum height of thermals.................. 19026 ft MSL (13729 ft AGL)
Forecast maximum temperature................... 61.0 F/16.6 C
Time of trigger temperature.................... 0830 MDT
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................. 17964 ft MSL (12667 ft AGL)
Thermal soaring outlook for Thursday 05/09..... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Winds aloft at 15 kft decrease b
Height of stable layer (12-18K ft MSL)......... 18060 ft MSL (12763 ft AGL)
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 19042 ft MSL (13745 ft AGL)
Wave soaring outlook for Thursday 05/09........ Poor
Remarks...
Sunrise/Sunset.................... 05:50:50 / 20:01:03 MDT
Total possible sunshine........... 14 hr 10 min 13 sec (850 min 13 sec)
Altitude of sun at 12:55:57 MDT... 67.59 degrees
Upper air data from numerical model forecast valid on 05/08/2024 at 0600 MDT
Freezing level.................. 6553 ft MSL (1256 ft AGL)
Convective condensation level... 14714 ft MSL (9417 ft AGL)
Lifted condensation level....... 17225 ft MSL (11928 ft AGL)
Lifted index.................... +4.5
K index......................... -4.4
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 -51.1 -60.0 255 16 8 1.7 1.0 M M M M M
45000 -48.5 -55.3 275 30 16 1.7 0.9 M M M M M
40000 -46.1 -51.0 260 49 25 1.5 0.8 M M M M M
38000 -45.2 -49.4 255 55 28 1.6 0.9 M M M M M
36000 -44.2 -47.6 255 59 30 1.6 0.9 M M M M M
34000 -43.3 -45.9 255 63 32 1.7 1.0 M M M M M
32000 -41.7 -43.1 255 58 30 2.7 1.5 M M M M M
30000 -40.1 -40.2 255 53 27 2.7 1.5 M M M M M
29000 -39.3 -38.7 260 48 24 2.7 1.5 36.5 97.6 15.4 M M
28000 -38.3 -36.9 265 40 21 2.7 1.5 32.9 91.3 12.9 M M
27000 -37.4 -35.3 270 35 18 2.8 1.5 30.3 86.6 11.0 M M
26000 -36.2 -33.2 280 30 16 6.2 3.4 28.2 82.8 9.5 M M
25000 -34.3 -29.7 285 27 14 6.2 3.4 26.8 80.2 8.5 M M
24000 -32.5 -26.5 295 24 13 6.2 3.4 25.5 77.9 7.6 M M
23000 -30.6 -23.1 300 23 12 6.8 3.7 24.3 75.7 6.7 M M
22000 -28.6 -19.5 285 24 12 6.7 3.7 23.1 73.6 5.8 M M
21000 -26.6 -15.9 275 25 13 6.5 3.6 22.1 71.7 5.0 M M
20000 -25.6 -14.1 275 22 12 0.0 0.0 19.7 67.5 3.1 M M
19500 -25.7 -14.3 280 19 10 -0.2 -0.1 17.9 64.3 1.5 M M
19000 -25.7 -14.3 290 15 8 -0.2 -0.1 16.2 61.1 0.0 M M
18500 -25.7 -14.3 300 12 6 0.0 0.0 14.5 58.1 -1.4 1182 6.0
18000 -25.8 -14.4 320 10 5 2.7 1.5 12.8 55.1 -2.9 1168 5.9
17500 -24.8 -12.6 330 12 6 7.1 3.9 12.3 54.1 -3.4 1125 5.7
17000 -23.8 -10.8 340 14 7 7.2 3.9 11.8 53.3 -3.8 1078 5.5
16500 -22.7 -8.9 345 15 8 7.4 4.1 11.4 52.5 -4.2 1031 5.2
16000 -21.6 -6.9 345 16 8 7.3 4.0 11.0 51.8 -4.6 983 5.0
15500 -20.5 -4.9 345 16 8 7.9 4.4 10.6 51.1 -5.0 935 4.8
15000 -19.3 -2.7 345 15 8 8.1 4.4 10.3 50.6 -5.3 884 4.5
14500 -17.4 0.7 340 14 7 8.8 4.8 10.0 50.0 -5.7 807 4.1
14000 -16.1 3.0 335 14 7 8.7 4.8 9.8 49.6 -5.8 753 3.8
13500 -14.8 5.4 330 15 8 8.6 4.7 9.6 49.3 -6.0 700 3.6
13000 -13.5 7.7 330 18 9 8.6 4.7 9.4 49.0 -6.3 646 3.3
12500 -12.3 9.9 320 19 10 8.4 4.6 9.2 48.6 -6.5 593 3.0
12000 -11.0 12.2 315 20 10 8.4 4.6 9.0 48.2 -6.7 541 2.8
11500 -9.8 14.4 305 22 11 7.7 4.2 8.7 47.7 -7.0 490 2.5
11000 -8.7 16.3 300 24 12 7.6 4.2 8.4 47.1 -7.4 442 2.2
10500 -7.5 18.5 295 26 14 7.9 4.3 8.1 46.5 -7.7 393 2.0
10250 -7.0 19.4 295 29 15 7.2 4.0 7.9 46.2 -7.9 368 1.9
10000 -6.4 20.5 295 31 16 9.8 5.4 7.8 46.0 -8.1 344 1.7
9750 -5.6 21.9 300 35 18 8.5 4.7 7.8 46.1 -8.1 313 1.6
9500 -5.2 22.6 295 38 19 5.0 2.7 7.5 45.5 -8.4 293 1.5
9250 -4.8 23.4 295 40 20 5.8 3.2 7.2 44.9 -8.7 273 1.4
9000 -4.4 24.1 290 42 22 5.7 3.1 6.9 44.3 -9.1 253 1.3
8750 -4.0 24.8 290 44 23 4.2 2.3 6.5 43.7 -9.4 235 1.2
8500 -3.8 25.2 290 43 22 3.2 1.7 6.0 42.8 -10.0 220 1.1
8250 -3.5 25.7 290 42 22 2.9 1.6 5.5 41.9 -10.5 206 1.0
8000 -3.3 26.1 285 41 21 5.1 2.8 5.0 41.0 -11.0 192 1.0
7750 -2.8 27.0 285 38 19 7.4 4.1 4.8 40.6 -11.3 170 0.9
7500 -2.3 27.9 285 36 18 6.8 3.7 4.6 40.2 -11.6 147 0.7
7250 -1.8 28.8 280 34 17 7.0 3.8 4.4 39.8 -11.8 125 0.6
7000 -1.2 29.8 280 32 16 8.8 4.8 4.2 39.5 -12.0 101 0.5
6750 -0.5 31.1 280 29 15 9.0 4.9 4.2 39.5 -12.1 72 0.4
6500 0.1 32.2 280 28 14 8.0 4.4 4.0 39.3 -12.2 47 0.2
6250 0.7 33.3 275 26 13 7.8 4.3 3.9 39.1 -12.4 21 0.1
6000 1.2 34.2 275 23 12 7.0 3.8 3.7 38.7 -12.6 M M
5750 1.7 35.1 270 20 10 7.3 4.0 3.5 38.4 -12.9 M M
5500 2.2 36.0 270 15 8 4.1 2.2 3.3 37.9 -13.2 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/08/2024 at 0900 MDT | 05/08/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.4 | CAPE... +3.6 LI... +4.9
CINH... -0.7 K Index... +0.2 | CINH... 0.0 K Index... +1.6
|
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 -51.5 -60.7 245 9 5 2.3 1.2 | -51.5 -60.7 250 10 5 1.8 1.0
45000 -48.1 -54.6 270 10 5 2.1 1.2 | -48.6 -55.5 245 16 8 1.9 1.1
40000 -45.3 -49.5 260 35 18 1.8 1.0 | -45.7 -50.3 255 32 16 1.9 1.1
38000 -44.6 -48.3 260 42 22 0.0 0.0 | -45.3 -49.5 260 36 19 -1.1 -0.6
36000 -44.6 -48.3 260 44 23 0.0 0.0 | -46.0 -50.8 260 39 20 -1.1 -0.6
34000 -44.6 -48.3 260 47 24 0.0 0.0 | -46.7 -52.1 260 41 21 -0.9 -0.5
32000 -44.5 -48.1 270 39 20 0.2 0.1 | -46.1 -51.0 265 38 20 1.1 0.6
30000 -44.3 -47.7 285 30 16 2.8 1.6 | -45.3 -49.5 275 36 18 5.2 2.8
29000 -42.7 -44.9 290 28 15 5.7 3.1 | -43.2 -45.8 275 36 18 6.8 3.7
28000 -41.0 -41.8 295 27 14 5.7 3.1 | -41.2 -42.2 275 35 18 6.8 3.7
27000 -39.2 -38.6 300 25 13 5.8 3.2 | -39.1 -38.4 275 35 18 6.8 3.7
26000 -37.2 -35.0 300 24 12 8.1 4.4 | -36.9 -34.4 280 34 18 7.9 4.4
25000 -34.7 -30.5 305 22 12 8.2 4.5 | -34.5 -30.1 280 33 17 8.0 4.4
24000 -32.3 -26.1 305 21 11 8.1 4.5 | -32.1 -25.8 280 31 16 8.0 4.4
23000 -30.0 -22.0 305 20 10 6.8 3.8 | -29.7 -21.5 280 29 15 8.2 4.5
22000 -27.9 -18.2 305 20 10 6.9 3.8 | -27.3 -17.1 280 27 14 8.2 4.5
21000 -25.9 -14.6 305 19 10 6.9 3.8 | -24.8 -12.6 280 25 13 8.5 4.6
20000 -24.5 -12.1 310 19 10 3.0 1.7 | -23.0 -9.4 280 23 12 4.7 2.6
19500 -24.1 -11.4 310 18 9 2.9 1.6 | -22.4 -8.3 280 21 11 4.7 2.6
19000 -23.6 -10.5 310 18 9 2.9 1.6 | -21.7 -7.1 280 19 10 4.7 2.6
18500 -23.2 -9.8 315 18 9 3.0 1.6 | -21.0 -5.8 280 18 9 4.7 2.6
18000 -22.8 -9.0 315 17 9 4.0 2.2 | -20.3 -4.5 280 16 8 3.6 2.0
17500 -22.0 -7.6 320 16 8 5.1 2.8 | -19.9 -3.8 285 15 8 3.1 1.7
17000 -21.3 -6.3 325 15 8 5.1 2.8 | -19.4 -2.9 290 13 7 3.5 1.9
16500 -20.4 -4.7 325 14 7 6.3 3.4 | -18.2 -0.8 290 11 6 5.9 3.2
16000 -19.0 -2.2 330 13 7 6.4 3.5 | -17.3 0.9 290 11 5 5.9 3.2
15500 -18.0 -0.4 330 13 7 7.1 3.9 | -16.5 2.3 290 10 5 5.8 3.2
15000 -17.0 1.4 330 13 6 7.0 3.8 | -15.6 3.9 290 9 5 5.9 3.2
14500 -15.9 3.4 330 12 6 7.7 4.2 | -14.7 5.5 285 9 5 6.6 3.6
14000 -14.7 5.5 325 12 6 7.6 4.2 | -13.7 7.3 285 9 4 6.6 3.6
13500 -13.6 7.5 320 11 6 8.0 4.4 | -12.7 9.1 285 8 4 6.7 3.7
13000 -12.4 9.7 320 12 6 8.0 4.4 | -11.7 10.9 290 8 4 6.6 3.6
12500 -11.2 11.8 315 13 7 8.5 4.6 | -10.6 12.9 290 8 4 7.7 4.2
12000 -9.9 14.2 315 14 7 8.5 4.7 | -9.5 14.9 295 9 4 7.5 4.1
11500 -8.6 16.5 315 16 8 8.6 4.7 | -8.3 17.1 295 9 5 9.2 5.1
11000 -7.3 18.9 310 18 9 8.8 4.8 | -6.9 19.6 300 10 5 9.3 5.1
10500 -6.1 21.0 310 20 10 7.3 4.0 | -5.6 21.9 300 11 6 7.7 4.2
10250 -5.6 21.9 310 21 11 6.5 3.5 | -5.1 22.8 305 11 5 7.6 4.2
10000 -5.1 22.8 310 22 11 9.5 5.2 | -4.4 24.1 305 11 6 11.6 6.4
9750 -4.3 24.3 305 23 12 9.6 5.3 | -3.4 25.9 300 13 7 11.7 6.4
9500 -3.7 25.3 305 24 13 6.5 3.6 | -2.8 27.0 300 14 7 8.5 4.7
9250 -3.2 26.2 305 26 13 6.9 3.8 | -2.1 28.2 305 16 8 9.2 5.1
9000 -2.7 27.1 300 27 14 7.3 4.0 | -1.4 29.5 305 17 9 9.5 5.2
8750 -2.2 28.0 300 27 14 5.5 3.0 | -0.7 30.7 300 19 10 9.1 5.0
8500 -1.9 28.6 300 28 14 3.8 2.1 | -0.1 31.8 300 19 10 8.3 4.6
8250 -1.6 29.1 295 28 14 4.2 2.3 | 0.5 32.9 300 19 10 8.1 4.5
8000 -1.3 29.7 295 28 15 4.3 2.4 | 1.1 34.0 300 20 10 9.7 5.3
7750 -1.0 30.2 290 27 14 6.4 3.5 | 1.9 35.4 300 20 10 10.2 5.6
7500 -0.4 31.3 290 25 13 7.7 4.2 | 2.6 36.7 300 20 10 9.0 4.9
7250 0.1 32.2 290 24 12 7.3 4.0 | 3.3 37.9 300 20 10 9.4 5.1
7000 0.7 33.3 290 22 12 8.0 4.4 | 4.0 39.2 300 20 10 8.7 4.8
6750 1.3 34.3 290 22 12 9.9 5.4 | 4.6 40.3 300 20 10 10.0 5.5
6500 2.1 35.8 290 21 11 10.6 5.8 | 5.5 41.9 300 19 10 11.4 6.2
6250 2.9 37.2 290 19 10 10.6 5.8 | 6.3 43.3 300 18 10 11.2 6.1
6000 3.7 38.7 290 18 9 11.6 6.4 | 7.2 45.0 300 18 9 12.3 6.8
5750 4.5 40.1 290 17 9 10.1 5.5 | 8.1 46.6 300 19 10 10.0 5.5
5500 5.3 41.5 290 15 8 11.2 6.1 | 8.9 48.0 300 16 8 15.2 8.3
05/08/2024 at 1500 MDT | 05/08/2024 at 1800 MDT
|
CAPE... 0.0 LI... +4.2 | CAPE... +0.9 LI... +2.1
CINH... 0.0 K Index... +3.0 | CINH... -0.3 K Index... +11.1
|
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 -51.9 -61.4 260 16 8 2.2 1.2 | -52.0 -61.6 245 9 4 2.2 1.2
45000 -48.4 -55.1 265 25 13 1.5 0.8 | -48.7 -55.7 270 17 9 0.7 0.4
40000 -46.1 -51.0 255 35 18 1.5 0.8 | -47.5 -53.5 265 34 18 0.8 0.4
38000 -45.9 -50.6 255 39 20 -1.2 -0.6 | -47.8 -54.0 260 39 20 -2.3 -1.3
36000 -46.6 -51.9 255 45 23 -1.2 -0.6 | -49.2 -56.6 260 43 22 -2.3 -1.2
34000 -47.3 -53.1 255 50 26 -0.2 -0.1 | -50.5 -58.9 255 47 24 0.9 0.5
32000 -46.4 -51.5 255 49 25 1.6 0.9 | -48.3 -54.9 260 47 24 3.6 2.0
30000 -45.0 -49.0 255 47 24 6.8 3.7 | -45.5 -49.9 265 46 24 8.7 4.8
29000 -42.9 -45.2 255 45 23 6.9 3.8 | -43.0 -45.4 265 44 23 8.3 4.6
28000 -40.8 -41.4 260 42 22 6.9 3.8 | -40.5 -40.9 265 42 22 8.3 4.6
27000 -38.8 -37.8 260 40 21 6.8 3.8 | -38.0 -36.4 265 40 21 8.3 4.6
26000 -36.5 -33.7 260 37 19 7.7 4.2 | -35.7 -32.3 265 37 19 7.8 4.3
25000 -34.2 -29.6 260 34 18 7.7 4.2 | -33.3 -27.9 260 33 17 7.8 4.3
24000 -31.9 -25.4 265 31 16 7.7 4.2 | -31.0 -23.8 255 30 15 7.8 4.3
23000 -29.7 -21.5 265 29 15 7.5 4.1 | -28.8 -19.8 255 26 14 7.2 4.0
22000 -27.4 -17.3 270 26 13 7.5 4.1 | -26.6 -15.9 255 22 12 7.2 4.0
21000 -25.2 -13.4 275 23 12 7.6 4.2 | -24.5 -12.1 260 18 9 6.9 3.8
20000 -23.2 -9.8 275 20 10 6.3 3.5 | -22.8 -9.0 265 14 7 5.4 3.0
19500 -22.3 -8.1 275 18 9 6.3 3.5 | -22.0 -7.6 265 12 6 5.4 3.0
19000 -21.3 -6.3 280 17 9 6.4 3.5 | -21.2 -6.2 270 9 5 5.4 3.0
18500 -20.4 -4.7 280 15 8 6.8 3.7 | -20.3 -4.5 280 7 4 5.4 3.0
18000 -19.7 -3.5 280 13 7 1.3 0.7 | -19.3 -2.7 280 6 3 8.1 4.4
17500 -19.6 -3.3 290 11 5 1.5 0.8 | -18.2 -0.8 275 6 3 7.9 4.3
17000 -19.4 -2.9 310 9 4 4.7 2.6 | -17.0 1.4 265 6 3 6.8 3.7
16500 -18.1 -0.6 305 7 4 8.5 4.6 | -16.1 3.0 260 8 4 6.4 3.5
16000 -16.8 1.8 300 6 3 8.6 4.7 | -15.1 4.8 255 9 5 6.0 3.3
15500 -15.1 4.8 290 5 3 7.4 4.0 | -14.4 6.1 260 9 5 5.0 2.7
15000 -14.0 6.8 290 5 3 7.2 3.9 | -13.6 7.5 275 9 4 5.0 2.7
14500 -12.9 8.8 295 5 2 6.9 3.8 | -12.3 9.9 295 8 4 6.0 3.3
14000 -11.9 10.6 305 4 2 6.8 3.7 | -11.4 11.5 310 7 4 6.4 3.5
13500 -10.9 12.4 320 4 2 6.3 3.4 | -10.4 13.3 315 6 3 6.9 3.8
13000 -10.0 14.0 335 4 2 6.3 3.5 | -9.4 15.1 325 6 3 7.3 4.0
12500 -9.1 15.6 325 4 2 6.3 3.5 | -8.2 17.2 330 7 3 8.2 4.5
12000 -8.1 17.4 305 4 2 6.4 3.5 | -7.0 19.4 330 8 4 8.5 4.7
11500 -7.0 19.4 300 6 3 9.6 4.9 | -5.7 21.7 325 8 4 9.5 5.2
11000 -5.8 21.6 305 8 4 9.1 5.0 | -4.3 24.3 325 9 5 9.1 5.0
10500 -4.5 23.9 305 8 4 8.5 4.7 | -3.1 26.4 325 9 5 7.4 4.1
10250 -3.8 25.2 305 8 4 8.8 4.8 | -2.5 27.5 325 9 5 9.7 5.3
10000 -3.1 26.4 305 8 4 11.0 6.0 | -1.6 29.1 320 9 5 12.7 7.0
9750 -2.3 27.9 305 8 4 11.1 6.1 | -0.7 30.7 320 9 5 10.8 5.9
9500 -1.5 29.3 305 8 4 9.8 5.4 | -0.0 32.0 320 9 5 9.4 5.2
9250 -0.8 30.6 305 8 4 10.0 5.5 | 0.7 33.3 320 9 5 9.7 5.3
9000 -0.0 32.0 305 8 4 10.4 5.7 | 1.4 34.5 320 9 5 8.6 4.7
8750 0.8 33.4 300 8 4 10.2 5.6 | 2.1 35.8 320 9 5 9.4 5.2
8500 1.5 34.7 300 8 4 9.5 5.2 | 2.8 37.0 320 9 5 10.6 5.8
8250 2.2 36.0 300 8 4 9.7 5.3 | 3.6 38.5 320 9 5 10.4 5.7
8000 3.0 37.4 300 8 4 10.3 5.7 | 4.4 39.9 320 9 5 10.4 5.7
7750 3.8 38.8 300 9 4 10.1 5.6 | 5.1 41.2 320 9 5 9.7 5.3
7500 4.5 40.1 300 9 4 9.4 5.2 | 5.8 42.4 320 9 5 9.1 5.0
7250 5.2 41.4 300 9 4 10.0 5.5 | 6.5 43.7 320 9 5 9.9 5.4
7000 6.0 42.8 300 9 4 10.9 6.0 | 7.3 45.1 320 9 5 10.7 5.9
6750 6.8 44.2 300 8 4 10.3 5.7 | 8.1 46.6 320 9 5 10.3 5.7
6500 7.5 45.5 300 8 4 9.5 5.2 | 8.9 48.0 320 9 5 10.0 5.5
6250 8.3 46.9 300 8 4 10.8 5.9 | 9.6 49.3 320 9 5 10.0 5.5
6000 9.1 48.4 300 8 4 12.2 6.7 | 10.4 50.7 315 9 4 10.1 5.5
5750 10.0 50.0 300 8 4 10.1 5.6 | 11.1 52.0 315 8 4 9.6 5.3
5500 10.8 51.4 300 8 4 15.7 8.6 | 11.9 53.4 315 8 4 12.7 6.9
________________________________________________________________________________
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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