Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
247
UXUS97 KBOU 141311
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0711 MDT Friday, June 14, 2024
This forecast is for Friday, June 14, 2024:
If the trigger temperature of 78.6 F/25.9 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 349 ft/min (1.8 m/s)
Maximum height of thermals.................. 10749 ft MSL (5432 ft AGL)
Forecast maximum temperature................... 85.0 F/29.9 C
Time of trigger temperature.................... 1030 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................. 9482 ft MSL (4165 ft AGL)
Thermal soaring outlook for Saturday 06/15..... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT).........
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 22293 ft MSL (16976 ft AGL)
Wave soaring outlook for Saturday 06/15........ Poor
Remarks...
Sunrise/Sunset.................... 05:30:49 / 20:29:05 MDT
Total possible sunshine........... 14 hr 58 min 17 sec (898 min 17 sec)
Altitude of sun at 12:59:57 MDT... 73.54 degrees
Upper air data from numerical model forecast valid on 06/14/2024 at 0600 MDT
Freezing level.................. 16524 ft MSL (11207 ft AGL)
Convective condensation level... 14060 ft MSL (8743 ft AGL)
Lifted condensation level....... 12805 ft MSL (7488 ft AGL)
Lifted index.................... -6.9
K index......................... +22.9
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 -61.0 -77.8 240 32 16 1.0 0.6 M M M M M
45000 -57.7 -71.9 230 43 22 4.4 2.4 M M M M M
40000 -51.4 -60.5 235 38 19 2.9 1.6 M M M M M
38000 -49.7 -57.5 245 33 17 2.8 1.6 M M M M M
36000 -48.0 -54.4 260 29 15 2.4 1.3 M M M M M
34000 -43.1 -45.6 260 27 14 9.3 5.1 M M M M M
32000 -36.9 -34.4 265 26 13 9.6 5.3 M M M M M
30000 -31.5 -24.7 255 22 11 9.0 5.0 43.9 111.0 11.0 M M
29000 -28.8 -19.8 250 19 10 9.1 5.0 43.7 110.6 10.9 M M
28000 -26.2 -15.2 245 18 9 6.8 3.7 43.3 110.0 10.8 M M
27000 -24.2 -11.6 235 18 9 6.6 3.6 42.0 107.6 9.9 M M
26000 -22.3 -8.1 230 18 9 6.6 3.6 40.8 105.5 9.0 M M
25000 -20.3 -4.5 220 19 10 6.7 3.7 39.8 103.6 8.2 M M
24000 -18.3 -0.9 220 21 11 6.9 3.8 38.6 101.5 7.3 M M
23000 -16.3 2.7 225 24 12 6.9 3.8 37.6 99.7 6.5 M M
22000 -14.2 6.4 225 26 13 7.3 4.0 36.7 98.0 5.8 M M
21000 -12.0 10.4 220 25 13 7.7 4.2 35.8 96.5 5.1 M M
20000 -9.8 14.4 215 24 12 7.8 4.3 35.2 95.3 4.4 M M
19500 -8.7 16.3 210 23 12 7.7 4.2 34.9 94.7 4.2 M M
19000 -7.4 18.7 210 23 12 9.6 5.3 34.7 94.4 4.0 M M
18500 -6.0 21.2 210 22 11 9.4 5.2 34.6 94.3 4.0 M M
18000 -4.6 23.7 210 20 11 9.5 5.2 34.6 94.2 3.9 M M
17500 -3.1 26.4 210 19 10 9.7 5.3 34.5 94.2 4.0 M M
17000 -0.9 30.4 210 17 9 9.2 5.0 34.5 94.2 4.0 M M
16500 0.4 32.7 210 17 9 8.8 4.8 34.4 93.8 3.8 M M
16000 1.6 34.9 210 16 8 8.7 4.8 34.2 93.5 3.7 M M
15500 2.9 37.2 210 15 8 8.7 4.8 34.0 93.2 3.6 M M
15000 4.2 39.6 215 14 7 8.6 4.7 33.8 92.9 3.4 M M
14500 5.5 41.9 215 13 7 9.0 4.9 33.7 92.6 3.3 M M
14000 6.9 44.4 215 12 6 9.0 4.9 33.5 92.4 3.1 M M
13500 8.2 46.8 215 11 6 8.2 4.5 33.4 92.1 3.0 M M
13000 9.3 48.7 215 10 5 7.8 4.3 33.1 91.6 2.7 M M
12500 10.4 50.7 210 9 4 7.2 4.0 32.8 91.0 2.4 M M
12000 11.4 52.5 210 8 4 6.4 3.5 32.3 90.1 1.9 M M
11500 12.3 54.1 215 7 4 5.8 3.2 31.7 89.1 1.3 M M
11000 12.8 55.0 230 7 4 4.2 2.3 30.9 87.6 0.4 M M
10500 13.4 56.1 245 7 4 3.0 1.6 30.1 86.1 -0.5 332 1.7
10250 13.4 56.1 250 8 4 1.8 1.0 29.4 85.0 -1.1 322 1.6
10000 13.6 56.5 255 8 4 3.2 1.8 28.9 84.0 -1.8 311 1.6
9750 13.7 56.7 260 8 4 3.5 1.9 28.4 83.1 -2.4 300 1.5
9500 13.8 56.8 265 8 4 3.1 1.7 27.9 82.2 -3.0 288 1.5
9250 14.0 57.2 265 7 4 2.3 1.3 27.3 81.2 -3.5 276 1.4
9000 14.1 57.4 265 7 4 2.7 1.5 26.8 80.2 -4.1 265 1.3
8750 14.3 57.7 260 6 3 3.0 1.7 26.2 79.2 -4.7 252 1.3
8500 14.5 58.1 250 6 3 3.3 1.8 25.7 78.3 -5.3 239 1.2
8250 14.7 58.5 235 6 3 3.9 2.1 25.2 77.4 -5.8 225 1.1
8000 14.9 58.8 220 6 3 3.6 2.0 24.8 76.6 -6.3 211 1.1
7750 15.1 59.2 205 6 3 3.2 1.7 24.3 75.7 -6.8 198 1.0
7500 15.3 59.5 195 7 4 3.7 2.0 23.8 74.9 -7.4 185 0.9
7250 15.6 60.1 190 7 4 4.1 2.2 23.4 74.1 -7.9 169 0.9
7000 15.8 60.4 185 8 4 4.4 2.4 22.9 73.3 -8.4 154 0.8
6750 16.2 61.2 175 8 4 5.1 2.8 22.6 72.6 -8.8 137 0.7
6500 16.5 61.7 170 8 4 4.3 2.4 22.2 72.0 -9.2 119 0.6
6250 16.8 62.2 165 7 4 3.1 1.7 21.7 71.1 -9.7 105 0.5
6000 17.0 62.6 160 6 3 5.0 2.7 21.3 70.3 -10.2 90 0.5
5750 17.4 63.3 155 5 3 3.9 2.1 20.9 69.7 -10.6 71 0.4
5500 17.4 63.3 140 4 2 -2.8 -1.5 20.2 68.4 -11.3 63 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/14/2024 at 0900 MDT | 06/14/2024 at 1200 MDT
|
CAPE... +1215.1 LI... -3.3 | CAPE... +1135.3 LI... -2.5
CINH... -207.3 K Index... +20.8 | CINH... -99.6 K Index... +22.1
|
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 -59.2 -74.6 245 29 15 2.6 1.4 | -59.1 -74.4 250 28 15 3.0 1.6
45000 -55.5 -67.9 235 47 24 1.9 1.1 | -55.2 -67.4 245 42 21 1.4 0.8
40000 -52.4 -62.3 230 46 24 3.3 1.8 | -52.7 -62.9 235 42 22 3.9 2.2
38000 -50.4 -58.7 225 33 17 3.3 1.8 | -50.3 -58.5 220 32 16 3.9 2.2
36000 -48.4 -55.1 215 21 11 3.1 1.7 | -48.0 -54.4 200 24 12 3.7 2.0
34000 -43.5 -46.3 210 18 10 9.1 5.0 | -43.2 -45.8 190 23 12 9.0 4.9
32000 -37.4 -35.3 210 18 9 9.6 5.3 | -37.7 -35.9 190 24 13 8.9 4.9
30000 -32.3 -26.1 210 22 11 8.4 4.6 | -32.1 -25.8 195 25 13 8.2 4.5
29000 -29.9 -21.8 215 24 12 8.4 4.6 | -29.6 -21.3 200 25 13 8.3 4.5
28000 -27.4 -17.3 215 26 13 7.6 4.2 | -27.2 -17.0 205 26 13 7.6 4.1
27000 -25.2 -13.4 220 28 15 7.5 4.1 | -25.0 -13.0 210 27 14 7.4 4.1
26000 -22.9 -9.2 220 31 16 7.6 4.1 | -22.8 -9.0 215 29 15 7.5 4.1
25000 -20.7 -5.3 225 34 17 7.4 4.1 | -20.6 -5.1 215 31 16 7.4 4.1
24000 -18.6 -1.5 225 34 18 6.9 3.8 | -18.4 -1.1 215 33 17 7.2 4.0
23000 -16.6 2.1 220 35 18 7.0 3.8 | -16.3 2.7 215 34 18 7.2 4.0
22000 -14.5 5.9 220 36 18 7.6 4.2 | -14.2 6.4 215 36 19 7.8 4.3
21000 -12.0 10.4 215 33 17 8.5 4.7 | -11.6 11.1 220 37 19 8.7 4.8
20000 -9.5 14.9 205 30 16 8.5 4.7 | -9.1 15.6 220 37 19 8.8 4.8
19500 -8.3 17.1 200 29 15 8.5 4.7 | -7.8 18.0 220 37 19 8.9 4.9
19000 -7.0 19.4 200 28 15 9.4 5.2 | -6.6 20.1 225 37 19 7.3 4.0
18500 -5.6 21.9 200 27 14 9.3 5.1 | -5.5 22.1 225 35 18 7.4 4.1
18000 -4.2 24.4 200 26 13 9.3 5.1 | -4.4 24.1 225 33 17 7.8 4.3
17500 -2.8 27.0 195 26 13 9.3 5.1 | -3.2 26.2 225 33 17 8.3 4.6
17000 -1.4 29.5 195 25 13 9.3 5.1 | -2.0 28.4 225 32 16 8.3 4.5
16500 -0.1 31.8 190 25 13 8.6 4.7 | -0.7 30.7 225 31 16 8.9 4.9
16000 1.2 34.2 185 24 12 8.7 4.8 | 0.6 33.1 225 30 15 8.9 4.9
15500 2.5 36.5 180 23 12 8.5 4.7 | 2.5 36.5 225 28 15 8.5 4.7
15000 4.4 39.9 180 19 10 8.5 4.6 | 3.8 38.8 225 27 14 8.6 4.7
14500 5.6 42.1 175 16 8 7.5 4.1 | 5.0 41.0 220 25 13 8.1 4.5
14000 6.7 44.1 180 13 7 7.5 4.1 | 6.2 43.2 220 21 11 8.1 4.4
13500 7.8 46.0 185 9 5 6.5 3.6 | 7.4 45.3 215 18 9 6.5 3.6
13000 8.6 47.5 195 6 3 6.1 3.4 | 8.2 46.8 215 14 7 5.6 3.1
12500 9.4 48.9 220 3 2 6.1 3.3 | 9.0 48.2 220 11 5 5.3 2.9
12000 10.2 50.4 285 3 1 6.1 3.3 | 9.6 49.3 230 8 4 5.1 2.8
11500 11.1 52.0 315 5 3 6.0 3.3 | 10.3 50.5 260 5 3 5.5 3.0
11000 11.9 53.4 320 8 4 5.5 3.0 | 11.2 52.2 290 6 3 6.0 3.3
10500 12.7 54.9 320 11 6 2.8 1.6 | 12.1 53.8 310 7 4 2.2 1.2
10250 12.8 55.0 320 11 6 2.4 1.3 | 12.2 54.0 315 7 4 4.0 2.2
10000 13.2 55.8 320 12 6 6.5 3.6 | 12.8 55.0 315 9 4 10.4 5.7
9750 13.6 56.5 320 13 6 6.6 3.6 | 13.5 56.3 320 10 5 9.2 5.1
9500 14.1 57.4 320 13 7 5.6 3.0 | 14.2 57.6 320 11 6 7.5 4.1
9250 14.4 57.9 320 13 7 3.9 2.2 | 14.5 58.1 330 11 6 4.0 2.2
9000 14.6 58.3 320 13 7 4.4 2.4 | 14.7 58.5 335 10 5 4.7 2.6
8750 15.0 59.0 320 13 7 5.2 2.8 | 14.9 58.8 350 9 5 4.5 2.5
8500 15.3 59.5 320 13 7 4.1 2.2 | 15.1 59.2 005 8 4 7.2 4.0
8250 15.5 59.9 315 12 6 3.2 1.8 | 15.8 60.4 005 8 4 10.2 5.6
8000 15.6 60.1 315 12 6 3.2 1.8 | 16.5 61.7 005 8 4 9.8 5.4
7750 15.8 60.4 310 11 6 2.8 1.6 | 17.3 63.1 010 8 4 9.9 5.4
7500 16.0 60.8 310 10 5 3.1 1.7 | 18.0 64.4 010 8 4 10.0 5.5
7250 16.1 61.0 310 7 4 3.7 2.0 | 18.7 65.7 010 8 4 10.0 5.5
7000 16.3 61.3 305 5 3 2.8 1.5 | 19.5 67.1 010 8 4 10.1 5.6
6750 16.4 61.5 295 2 1 4.8 2.6 | 20.3 68.5 010 8 4 10.8 5.9
6500 16.9 62.4 275 1 1 9.2 5.1 | 21.1 70.0 010 8 4 10.8 5.9
6250 17.6 63.7 270 1 1 10.8 5.9 | 21.9 71.4 015 8 4 11.2 6.2
6000 18.4 65.1 265 1 0 8.8 4.8 | 22.7 72.9 015 8 4 8.9 4.9
5750 19.0 66.2 260 1 0 11.8 6.5 | 23.4 74.1 015 8 4 16.0 8.8
5500 20.3 68.5 260 1 0 21.6 11.9 | 25.3 77.5 015 8 4 34.6 19.0
06/14/2024 at 1500 MDT | 06/14/2024 at 1800 MDT
|
CAPE... +1525.7 LI... -4.8 | CAPE... +158.4 LI... -1.2
CINH... 0.0 K Index... +34.7 | CINH... -132.1 K Index... +28.5
|
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 -58.6 -73.5 250 28 14 3.8 2.1 | -58.7 -73.7 255 28 14 3.8 2.1
45000 -55.3 -67.5 250 40 21 -1.4 -0.8 | -54.9 -66.8 250 26 13 -0.5 -0.3
40000 -56.2 -69.2 245 50 26 8.2 4.5 | -54.5 -66.1 145 24 12 8.4 4.6
38000 -51.2 -60.2 240 49 25 8.2 4.5 | -49.6 -57.3 150 23 12 8.2 4.5
36000 -46.3 -51.3 235 48 25 8.2 4.5 | -44.1 -47.4 155 21 11 8.2 4.5
34000 -40.0 -40.0 230 46 23 9.4 5.2 | -39.4 -38.9 170 20 10 7.9 4.4
32000 -34.4 -29.9 230 43 22 9.4 5.2 | -34.6 -30.3 185 20 11 7.8 4.3
30000 -29.4 -20.9 230 39 20 8.1 4.5 | -30.1 -22.2 200 22 11 7.4 4.0
29000 -27.0 -16.6 225 37 19 8.2 4.5 | -28.0 -18.4 210 24 12 7.4 4.0
28000 -24.6 -12.3 225 35 18 7.4 4.1 | -25.8 -14.4 215 25 13 7.1 3.9
27000 -22.5 -8.5 220 34 18 7.1 3.9 | -23.8 -10.8 220 28 14 6.8 3.7
26000 -20.4 -4.7 220 33 17 7.1 3.9 | -21.8 -7.2 225 31 16 6.8 3.7
25000 -18.3 -0.9 215 32 17 7.1 3.9 | -19.8 -3.6 230 34 17 6.9 3.8
24000 -16.4 2.5 210 32 17 6.4 3.5 | -17.9 -0.2 235 35 18 6.3 3.5
23000 -14.6 5.7 210 32 17 6.4 3.5 | -16.0 3.2 240 37 19 6.3 3.5
22000 -12.7 9.1 205 32 17 6.4 3.5 | -14.2 6.4 240 38 19 6.3 3.5
21000 -11.0 12.2 205 31 16 6.0 3.3 | -11.8 10.8 245 36 19 6.6 3.6
20000 -9.2 15.4 205 29 15 6.0 3.3 | -9.9 14.2 250 35 18 6.6 3.6
19500 -8.3 17.1 200 28 14 6.0 3.3 | -8.9 16.0 250 34 17 6.7 3.7
19000 -7.5 18.5 200 27 14 5.9 3.3 | -7.9 17.8 255 33 17 6.5 3.6
18500 -6.6 20.1 200 26 13 5.9 3.2 | -7.0 19.4 255 31 16 6.5 3.6
18000 -5.8 21.6 200 25 13 6.0 3.3 | -6.0 21.2 260 30 15 6.5 3.6
17500 -4.9 23.2 195 24 12 6.3 3.4 | -5.1 22.8 260 28 14 6.4 3.5
17000 -3.5 25.7 195 22 11 6.4 3.5 | -4.2 24.4 265 27 14 6.5 3.5
16500 -2.6 27.3 195 21 11 6.9 3.8 | -3.3 26.1 265 25 13 6.5 3.5
16000 -1.6 29.1 195 19 10 6.8 3.7 | -2.3 27.9 265 23 12 6.4 3.5
15500 -0.6 30.9 195 18 9 7.4 4.1 | -1.3 29.7 270 21 11 7.5 4.1
15000 0.5 32.9 190 16 8 7.4 4.1 | -0.2 31.6 270 20 10 7.8 4.3
14500 1.6 34.9 190 14 7 7.3 4.0 | 0.9 33.6 270 18 9 8.2 4.5
14000 2.7 36.9 185 12 6 7.3 4.0 | 2.2 36.0 270 16 8 8.6 4.7
13500 3.7 38.7 180 9 5 7.2 4.0 | 3.5 38.3 275 15 8 8.5 4.6
13000 4.7 40.5 165 7 4 7.2 4.0 | 4.7 40.5 275 13 7 7.8 4.3
12500 5.6 42.1 145 5 3 7.6 4.2 | 5.8 42.4 275 11 6 7.8 4.3
12000 6.8 44.2 115 6 3 8.7 4.8 | 6.8 44.2 280 9 5 6.6 3.6
11500 8.0 46.4 100 7 4 8.9 4.9 | 7.8 46.0 285 7 4 6.8 3.7
11000 9.3 48.7 095 8 4 9.4 5.2 | 8.8 47.8 295 6 3 6.3 3.4
10500 10.7 51.3 090 9 5 5.4 3.0 | 9.7 49.5 315 4 2 6.3 3.5
10250 11.0 51.8 090 9 5 7.0 3.8 | 10.1 50.2 330 4 2 4.7 2.6
10000 11.9 53.4 090 9 5 13.5 7.4 | 10.4 50.7 345 4 2 4.6 2.5
9750 12.7 54.9 090 9 5 12.2 6.7 | 10.7 51.3 360 4 2 5.8 3.2
9500 13.6 56.5 090 9 5 10.8 5.9 | 11.1 52.0 015 5 2 5.4 3.0
9250 14.3 57.7 085 9 5 7.5 4.1 | 11.5 52.7 030 5 3 5.4 3.0
9000 14.9 58.8 085 9 5 9.4 5.2 | 11.8 53.2 035 7 3 4.3 2.4
8750 15.7 60.3 085 9 5 11.2 6.2 | 12.1 53.8 040 8 4 3.5 1.9
8500 16.5 61.7 085 9 5 10.5 5.8 | 12.3 54.1 045 9 4 3.7 2.0
8250 17.3 63.1 085 9 5 10.3 5.7 | 12.6 54.7 050 10 5 3.9 2.1
8000 18.1 64.6 085 9 5 10.1 5.5 | 12.8 55.0 055 12 6 3.3 1.8
7750 18.8 65.8 085 9 5 9.7 5.3 | 13.0 55.4 055 13 7 2.1 1.2
7500 19.5 67.1 085 9 5 10.3 5.6 | 13.1 55.6 055 14 7 1.3 0.7
7250 20.3 68.5 080 9 5 11.1 6.1 | 13.1 55.6 060 15 8 0.9 0.5
7000 21.1 70.0 080 9 5 10.5 5.7 | 13.1 55.6 060 17 9 0.9 0.5
6750 21.9 71.4 080 9 5 9.3 5.1 | 13.1 55.6 060 18 9 0.4 0.2
6500 22.6 72.7 080 9 5 10.2 5.6 | 13.2 55.8 060 19 10 2.9 1.6
6250 23.4 74.1 080 9 5 11.8 6.5 | 13.5 56.3 065 19 10 5.7 3.1
6000 24.2 75.6 080 9 5 9.9 5.4 | 13.7 56.7 065 18 9 4.0 2.2
5750 25.0 77.0 080 9 5 13.5 7.4 | 14.0 57.2 065 18 9 6.9 3.8
5500 26.5 79.7 075 9 4 25.9 14.2 | 16.2 61.2 065 11 6 18.5 10.1
________________________________________________________________________________
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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