Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
836
UXUS97 KBOU 161341
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0740 MDT Monday, June 16, 2025
This forecast is for Monday, June 16, 2025:
If the trigger temperature of 87.5 F/30.8 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 573 ft/min (2.9 m/s)
Maximum height of thermals.................. 13925 ft MSL (8608 ft AGL)
Forecast maximum temperature................... 91.0 F/33.2 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ 1500 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7920 ft MSL (2603 ft AGL)
Thermal soaring outlook for Tuesday 06/17...... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 40724 ft MSL (35407 ft AGL)
Wave soaring outlook for Tuesday 06/17......... Poor
Remarks...
Sunrise/Sunset.................... 05:30:55 / 20:29:44 MDT
Total possible sunshine........... 14 hr 58 min 49 sec (898 min 49 sec)
Altitude of sun at 13:00:20 MDT... 73.61 degrees
Upper air data from numerical model forecast valid on 06/16/2025 at 0600 MDT
Freezing level.................. 16428 ft MSL (11111 ft AGL)
Convective condensation level... 18344 ft MSL (13027 ft AGL)
Lifted condensation level....... 18146 ft MSL (12830 ft AGL)
Lifted index.................... -3.9
K index......................... +11.7
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 -61.8 -79.2 285 53 27 3.2 1.7 M M M M M
45000 -57.2 -71.0 290 72 37 2.3 1.3 M M M M M
40000 -53.4 -64.1 290 82 42 5.2 2.8 M M M M M
38000 -50.4 -58.7 285 66 34 5.0 2.7 M M M M M
36000 -47.4 -53.3 280 50 26 5.0 2.8 M M M M M
34000 -43.9 -47.0 280 41 21 6.3 3.4 M M M M M
32000 -40.1 -40.2 280 35 18 6.3 3.5 M M M M M
30000 -35.1 -31.2 275 32 16 7.8 4.3 39.3 102.7 4.9 M M
29000 -32.8 -27.0 275 31 16 7.9 4.3 38.6 101.4 4.4 M M
28000 -30.4 -22.7 275 30 16 7.7 4.2 38.0 100.3 4.0 M M
27000 -28.2 -18.8 275 29 15 7.6 4.2 37.0 98.6 3.3 M M
26000 -25.9 -14.6 270 28 15 7.6 4.2 36.2 97.1 2.6 M M
25000 -23.7 -10.7 270 27 14 7.8 4.3 35.5 95.9 2.1 M M
24000 -21.0 -5.8 265 26 13 8.9 4.9 35.1 95.1 1.7 M M
23000 -18.4 -1.1 265 24 12 8.9 4.9 34.8 94.6 1.5 M M
22000 -15.7 3.7 265 22 11 9.0 5.0 34.6 94.2 1.3 M M
21000 -13.0 8.6 265 21 11 9.2 5.0 34.3 93.7 1.1 M M
20000 -10.3 13.5 265 21 11 9.2 5.0 34.1 93.4 0.9 M M
19500 -8.9 16.0 265 20 10 9.2 5.1 34.0 93.2 0.9 M M
19000 -7.5 18.5 265 20 10 9.1 5.0 33.9 93.1 0.8 M M
18500 -6.2 20.8 265 19 10 9.1 5.0 33.8 92.9 0.7 M M
18000 -4.8 23.4 265 18 9 9.3 5.1 33.7 92.7 0.6 M M
17500 -3.4 25.9 270 18 9 9.5 5.2 33.7 92.6 0.5 M M
17000 -2.0 28.4 270 17 9 9.5 5.2 33.6 92.5 0.5 M M
16500 0.1 32.2 270 15 8 9.4 5.1 33.5 92.4 0.4 M M
16000 1.5 34.7 270 14 7 9.4 5.1 33.5 92.3 0.3 M M
15500 2.9 37.2 275 13 7 9.4 5.2 33.4 92.2 0.3 M M
15000 4.3 39.7 275 12 6 9.5 5.2 33.4 92.1 0.2 M M
14500 5.7 42.3 280 11 5 9.1 5.0 33.3 91.9 0.1 M M
14000 7.0 44.6 280 10 5 9.1 5.0 33.2 91.7 -0.0 773 3.9
13500 8.4 47.1 285 9 4 9.1 5.0 33.1 91.6 -0.1 718 3.6
13000 9.7 49.5 290 8 4 9.1 5.0 33.0 91.3 -0.2 663 3.4
12500 11.0 51.8 300 7 4 8.9 4.9 32.9 91.2 -0.4 608 3.1
12000 12.3 54.1 305 7 3 8.8 4.8 32.7 90.9 -0.5 555 2.8
11500 13.6 56.5 315 6 3 8.7 4.8 32.6 90.6 -0.7 502 2.5
11000 14.9 58.8 325 7 3 8.4 4.6 32.4 90.3 -0.9 449 2.3
10500 16.1 61.0 330 7 4 5.0 2.7 32.2 90.0 -1.1 396 2.0
10250 16.4 61.5 335 7 4 5.5 3.0 31.7 89.0 -1.6 382 1.9
10000 17.1 62.8 335 7 4 10.5 5.8 31.7 89.0 -1.7 354 1.8
9750 17.8 64.0 340 8 4 9.5 5.2 31.7 89.0 -1.7 326 1.7
9500 18.4 65.1 340 8 4 8.8 4.8 31.6 89.0 -1.7 297 1.5
9250 19.0 66.2 340 8 4 7.0 3.8 31.5 88.7 -1.9 273 1.4
9000 19.5 67.1 340 9 4 7.4 4.0 31.3 88.3 -2.1 250 1.3
8750 20.1 68.2 340 9 5 8.0 4.4 31.1 88.0 -2.3 226 1.1
8500 20.7 69.3 340 9 5 7.6 4.2 31.0 87.7 -2.5 202 1.0
8250 21.2 70.2 340 10 5 7.9 4.4 30.8 87.5 -2.7 178 0.9
8000 21.7 71.1 340 10 5 6.5 3.6 30.6 87.2 -2.8 154 0.8
7750 22.1 71.8 335 10 5 5.3 2.9 30.3 86.6 -3.2 136 0.7
7500 22.5 72.5 335 10 5 4.2 2.3 30.0 85.9 -3.6 118 0.6
7250 22.6 72.7 330 9 5 2.8 1.5 29.5 85.0 -4.2 105 0.5
7000 22.8 73.0 325 8 4 2.9 1.6 28.9 84.1 -4.7 93 0.5
6750 22.9 73.2 320 7 4 2.1 1.2 28.4 83.1 -5.3 81 0.4
6500 22.8 73.0 310 7 3 -6.2 -3.4 27.6 81.7 -6.2 77 0.4
6250 22.0 71.6 290 6 3 -12.5 -6.9 26.0 78.8 -7.8 96 0.5
6000 21.1 70.0 265 6 3 -8.9 -4.9 24.5 76.0 -9.4 115 0.6
5750 20.3 68.5 245 6 3 -14.4 -7.9 23.0 73.4 -11.0 131 0.7
5500 18.4 65.1 225 6 3 -32.3 -17.7 20.5 69.0 -13.6 179 0.9
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/16/2025 at 0900 MDT | 06/16/2025 at 1200 MDT
|
CAPE... +374.4 LI... +0.5 | CAPE... +1007.2 LI... -2.5
CINH... -424.5 K Index... +10.9 | CINH... -112.4 K Index... +8.7
|
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 -62.0 -79.6 285 46 24 3.0 1.7 | -61.9 -79.4 280 46 24 3.3 1.8
45000 -57.4 -71.3 285 69 35 2.6 1.4 | -57.2 -71.0 280 71 37 2.1 1.2
40000 -53.3 -63.9 290 84 43 5.3 2.9 | -53.7 -64.7 285 87 45 5.9 3.2
38000 -50.2 -58.4 285 69 35 5.1 2.8 | -50.3 -58.5 285 75 39 5.7 3.1
36000 -47.2 -53.0 285 53 27 5.2 2.8 | -46.9 -52.4 285 63 32 5.7 3.1
34000 -43.4 -46.1 280 44 23 6.8 3.7 | -42.9 -45.2 285 52 27 7.0 3.8
32000 -39.3 -38.7 275 39 20 6.8 3.7 | -38.1 -36.6 280 42 21 7.0 3.8
30000 -34.9 -30.8 275 28 15 6.4 3.5 | -34.2 -29.6 270 32 16 6.5 3.6
29000 -33.0 -27.4 275 23 12 6.4 3.5 | -32.2 -26.0 265 27 14 6.5 3.6
28000 -31.1 -24.0 275 18 9 7.3 4.0 | -30.3 -22.5 260 23 12 6.7 3.7
27000 -28.8 -19.8 270 17 9 7.8 4.3 | -28.3 -18.9 260 21 11 6.8 3.8
26000 -26.5 -15.7 265 17 9 7.9 4.3 | -26.2 -15.2 260 21 11 6.9 3.8
25000 -24.1 -11.4 255 17 9 8.1 4.5 | -24.2 -11.6 265 20 10 7.1 3.9
24000 -21.6 -6.9 255 17 9 8.9 4.9 | -21.6 -6.9 265 20 10 9.0 4.9
23000 -18.9 -2.0 255 17 9 8.9 4.9 | -18.9 -2.0 265 20 10 9.0 4.9
22000 -16.3 2.7 260 17 9 9.1 5.0 | -16.3 2.7 265 20 10 9.1 5.0
21000 -13.4 7.9 260 17 9 9.5 5.2 | -13.5 7.7 265 20 10 9.4 5.1
20000 -10.5 13.1 265 16 8 9.5 5.2 | -10.7 12.7 265 20 10 9.4 5.1
19500 -9.1 15.6 270 16 8 9.5 5.2 | -9.3 15.3 265 20 10 9.4 5.1
19000 -7.7 18.1 270 16 8 9.4 5.2 | -7.9 17.8 265 19 10 9.5 5.2
18500 -6.3 20.7 275 15 8 9.4 5.2 | -6.5 20.3 265 18 9 9.5 5.2
18000 -4.8 23.4 275 14 7 9.3 5.1 | -5.0 23.0 265 17 9 9.5 5.2
17500 -3.5 25.7 280 13 7 9.3 5.1 | -2.9 26.8 265 16 8 9.5 5.2
17000 -2.1 28.2 280 12 6 9.3 5.1 | -1.5 29.3 265 15 8 9.5 5.2
16500 -0.7 30.7 285 11 6 9.4 5.2 | -0.1 31.8 265 15 8 9.4 5.2
16000 0.7 33.3 285 11 6 9.4 5.2 | 1.3 34.3 265 14 7 9.4 5.2
15500 2.8 37.0 290 10 5 9.5 5.2 | 2.7 36.9 260 13 7 9.5 5.2
15000 4.2 39.6 290 10 5 9.5 5.2 | 4.2 39.6 260 13 7 9.5 5.2
14500 5.6 42.1 290 9 5 9.5 5.2 | 5.6 42.1 260 12 6 9.1 5.0
14000 7.0 44.6 290 9 4 9.5 5.2 | 6.9 44.4 260 11 6 9.0 5.0
13500 8.4 47.1 290 8 4 9.4 5.1 | 8.2 46.8 255 11 5 8.9 4.9
13000 9.7 49.5 285 7 4 9.3 5.1 | 9.5 49.1 255 10 5 8.8 4.8
12500 11.1 52.0 285 6 3 9.2 5.0 | 10.8 51.4 255 9 5 8.6 4.7
12000 12.4 54.3 285 5 3 9.0 5.0 | 12.1 53.8 255 8 4 8.4 4.6
11500 13.8 56.8 285 4 2 8.8 4.8 | 13.3 55.9 255 8 4 8.2 4.5
11000 15.0 59.0 295 3 2 8.1 4.4 | 14.4 57.9 250 6 3 7.4 4.0
10500 16.2 61.2 305 3 1 4.6 2.5 | 15.5 59.9 250 5 3 4.9 2.7
10250 16.4 61.5 310 3 1 5.6 3.1 | 15.7 60.3 250 5 3 5.4 2.9
10000 17.2 63.0 320 3 1 10.9 6.0 | 16.3 61.3 255 5 2 9.0 4.9
9750 17.9 64.2 335 3 1 10.0 5.5 | 16.9 62.4 260 4 2 8.3 4.6
9500 18.6 65.5 345 3 1 8.6 4.7 | 17.5 63.5 265 4 2 7.5 4.1
9250 19.1 66.4 345 3 2 6.6 3.6 | 17.9 64.2 285 3 2 4.3 2.3
9000 19.7 67.5 345 4 2 7.9 4.3 | 18.1 64.6 320 3 2 2.3 1.3
8750 20.3 68.5 345 4 2 8.6 4.7 | 18.2 64.8 355 4 2 1.6 0.9
8500 20.9 69.6 345 4 2 8.1 4.5 | 18.3 64.9 010 6 3 3.2 1.7
8250 21.5 70.7 340 5 3 7.7 4.2 | 18.5 65.3 030 8 4 5.6 3.1
8000 22.1 71.8 340 6 3 7.8 4.3 | 18.7 65.7 040 10 5 6.5 3.6
7750 22.7 72.9 335 6 3 8.2 4.5 | 19.1 66.4 045 10 5 6.0 3.3
7500 23.3 73.9 330 7 4 7.1 3.9 | 19.5 67.1 045 11 6 8.7 4.8
7250 23.7 74.7 325 7 4 6.0 3.3 | 20.3 68.5 045 11 6 11.5 6.3
7000 24.2 75.6 320 7 4 6.7 3.7 | 21.1 70.0 045 11 6 10.6 5.8
6750 24.7 76.5 315 8 4 6.2 3.4 | 21.9 71.4 050 11 6 9.9 5.4
6500 24.9 76.8 310 8 4 1.2 0.6 | 22.6 72.7 050 11 6 10.6 5.8
6250 24.8 76.6 300 7 3 -2.6 -1.4 | 23.5 74.3 050 11 5 12.0 6.6
6000 24.6 76.3 285 6 3 0.7 0.4 | 24.3 75.7 050 10 5 10.0 5.5
5750 24.6 76.3 265 6 3 -2.6 -1.4 | 25.1 77.2 050 10 5 14.2 7.8
5500 23.8 74.8 255 5 2 -16.8 -9.2 | 26.6 79.9 050 10 5 27.9 15.3
06/16/2025 at 1500 MDT | 06/16/2025 at 1800 MDT
|
CAPE... +1703.5 LI... -4.9 | CAPE... +2012.7 LI... -5.9
CINH... -56.7 K Index... +16.3 | CINH... -53.8 K Index... +23.2
|
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 -62.6 -80.7 265 47 24 3.0 1.7 | -62.9 -81.2 270 54 28 3.3 1.8
45000 -58.1 -72.6 275 79 41 2.4 1.3 | -58.3 -72.9 275 84 43 1.9 1.0
40000 -54.0 -65.2 285 93 48 6.3 3.4 | -55.0 -67.0 285 92 47 6.7 3.7
38000 -50.3 -58.5 285 85 44 6.1 3.3 | -51.1 -60.0 285 87 45 6.4 3.5
36000 -46.7 -52.1 290 77 40 6.1 3.4 | -47.3 -53.1 285 81 42 6.5 3.5
34000 -42.8 -45.0 285 64 33 6.6 3.6 | -43.1 -45.6 285 69 35 7.0 3.9
32000 -38.8 -37.8 275 50 26 6.6 3.6 | -38.9 -38.0 280 54 28 7.1 3.9
30000 -34.2 -29.6 265 39 20 6.9 3.8 | -33.9 -29.0 270 40 21 7.8 4.3
29000 -32.2 -26.0 260 36 18 6.9 3.8 | -31.5 -24.7 260 36 18 7.8 4.3
28000 -30.1 -22.2 255 32 17 7.9 4.3 | -29.2 -20.6 255 32 16 8.3 4.5
27000 -27.6 -17.7 255 31 16 8.4 4.6 | -26.7 -16.1 250 30 16 8.5 4.7
26000 -25.1 -13.2 255 29 15 8.5 4.6 | -24.2 -11.6 250 29 15 8.5 4.7
25000 -22.6 -8.7 250 27 14 8.5 4.7 | -21.7 -7.1 245 28 14 8.5 4.7
24000 -20.2 -4.4 250 26 13 8.3 4.6 | -19.4 -2.9 245 27 14 7.5 4.1
23000 -17.7 0.1 255 24 12 8.4 4.6 | -17.2 1.0 245 26 13 7.5 4.1
22000 -15.2 4.6 255 22 11 8.3 4.6 | -15.0 5.0 245 24 13 7.6 4.1
21000 -12.8 9.0 255 21 11 8.2 4.5 | -12.8 9.0 245 23 12 7.5 4.1
20000 -10.4 13.3 255 20 10 8.2 4.5 | -10.5 13.1 245 22 11 7.5 4.1
19500 -9.1 15.6 255 19 10 8.1 4.4 | -9.4 15.1 245 21 11 7.5 4.1
19000 -7.9 17.8 255 18 9 9.1 5.0 | -8.3 17.1 245 20 11 8.0 4.4
18500 -6.5 20.3 255 18 9 9.0 4.9 | -7.1 19.2 245 20 10 8.0 4.4
18000 -5.2 22.6 255 17 9 9.0 4.9 | -5.9 21.4 245 20 10 8.2 4.5
17500 -3.9 25.0 255 16 8 8.9 4.9 | -4.7 23.5 240 19 10 8.6 4.7
17000 -2.5 27.5 250 15 8 8.8 4.9 | -3.4 25.9 240 19 10 8.6 4.7
16500 -1.2 29.8 250 15 8 9.6 5.2 | -2.1 28.2 240 18 9 9.3 5.1
16000 0.9 33.6 250 14 7 9.5 5.2 | -0.1 31.8 235 18 9 9.3 5.1
15500 2.3 36.1 250 13 7 9.3 5.1 | 1.3 34.3 235 18 9 9.3 5.1
15000 3.7 38.7 250 13 7 9.3 5.1 | 2.7 36.9 230 18 9 9.3 5.1
14500 5.1 41.2 245 12 6 9.2 5.1 | 4.1 39.4 230 17 9 9.5 5.2
14000 6.5 43.7 245 12 6 9.2 5.1 | 5.5 41.9 225 17 9 9.6 5.3
13500 7.9 46.2 245 11 6 9.2 5.0 | 6.9 44.4 225 17 9 9.5 5.2
13000 9.3 48.7 240 11 6 9.2 5.0 | 8.4 47.1 220 17 9 9.5 5.2
12500 10.7 51.3 235 10 5 9.2 5.0 | 9.8 49.6 220 16 8 9.5 5.2
12000 12.0 53.6 235 10 5 9.1 5.0 | 11.2 52.2 220 16 8 9.6 5.3
11500 13.4 56.1 230 9 5 9.0 4.9 | 12.7 54.9 220 16 8 9.5 5.2
11000 14.7 58.5 230 8 4 8.3 4.6 | 14.0 57.2 225 13 7 8.5 4.7
10500 16.0 60.8 230 6 3 5.1 2.8 | 15.3 59.5 230 11 5 4.9 2.7
10250 16.2 61.2 230 5 3 4.4 2.4 | 15.5 59.9 230 10 5 4.9 2.7
10000 16.7 62.1 225 3 2 8.4 4.6 | 16.1 61.0 235 7 4 9.9 5.4
9750 17.2 63.0 220 2 1 7.8 4.3 | 16.7 62.1 245 5 3 8.6 4.7
9500 17.7 63.9 000 0 0 6.9 3.8 | 17.3 63.1 260 3 2 9.0 4.9
9250 17.9 64.2 070 2 1 4.1 2.2 | 17.9 64.2 300 2 1 8.3 4.5
9000 18.1 64.6 070 4 2 4.1 2.2 | 18.4 65.1 345 2 1 7.7 4.2
8750 18.3 64.9 070 5 3 4.4 2.4 | 18.9 66.0 020 3 1 7.7 4.2
8500 18.4 65.1 070 6 3 6.3 3.5 | 19.4 66.9 035 4 2 7.7 4.2
8250 18.9 66.0 070 7 3 10.2 5.6 | 19.9 67.8 045 5 2 7.8 4.3
8000 19.7 67.5 075 7 3 9.9 5.4 | 20.4 68.7 055 5 3 6.9 3.8
7750 20.3 68.5 075 7 3 8.4 4.6 | 20.8 69.4 060 6 3 5.7 3.1
7500 20.9 69.6 075 7 4 9.6 5.3 | 21.1 70.0 065 6 3 6.6 3.6
7250 21.7 71.1 075 7 4 10.9 6.0 | 21.6 70.9 070 6 3 7.6 4.1
7000 22.5 72.5 075 7 4 10.4 5.7 | 22.1 71.8 075 7 3 7.6 4.2
6750 23.2 73.8 075 7 4 9.5 5.2 | 22.6 72.7 080 7 4 6.8 3.7
6500 24.0 75.2 075 7 4 10.1 5.6 | 23.1 73.6 085 7 4 8.8 4.8
6250 24.8 76.6 080 7 3 11.4 6.2 | 23.9 75.0 085 7 4 10.8 5.9
6000 25.6 78.1 080 7 3 10.2 5.6 | 24.6 76.3 090 7 4 10.2 5.6
5750 26.4 79.5 080 7 3 12.2 6.7 | 25.4 77.7 090 7 4 8.9 4.9
5500 27.5 81.5 080 6 3 20.3 11.2 | 25.9 78.6 090 6 3 6.6 3.6
________________________________________________________________________________
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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