Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
942
UXUS97 KBOU 041316
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0714 MDT Friday, July 4, 2025
This forecast is for Friday, July 4, 2025:
If the trigger temperature of 75.5 F/24.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1017 ft/min (5.2 m/s)
Maximum height of thermals.................. 16328 ft MSL (10995 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Overcast thin high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 13004 ft MSL (7671 ft AGL)
Thermal soaring outlook for Saturday 07/05..... Good
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 NVA
Potential height of wave....................... 15919 ft MSL (10586 ft AGL)
Wave soaring outlook for Saturday 07/05........ Poor
Remarks...
Sunrise/Sunset.................... 05:37:05 / 20:30:58 MDT
Total possible sunshine........... 14 hr 53 min 53 sec (893 min 53 sec)
Altitude of sun at 13:04:02 MDT... 73.01 degrees
Upper air data from numerical model forecast valid on 07/04/2025 at 0600 MDT
Freezing level.................. 15459 ft MSL (10126 ft AGL)
Convective condensation level... 13466 ft MSL (8133 ft AGL)
Lifted condensation level....... 14587 ft MSL (9254 ft AGL)
Lifted index.................... -2.9
K index......................... +29.1
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 -62.6 -80.7 230 26 13 3.2 1.7 M M M M M
45000 -56.5 -69.7 230 35 18 5.7 3.1 M M M M M
40000 -48.0 -54.4 220 42 22 5.9 3.2 M M M M M
38000 -44.5 -48.1 220 40 21 5.9 3.2 M M M M M
36000 -41.0 -41.8 215 38 20 5.9 3.2 M M M M M
34000 -37.1 -34.8 210 35 18 5.7 3.1 M M M M M
32000 -33.7 -28.7 205 32 17 5.5 3.0 M M M M M
30000 -29.3 -20.7 200 30 16 7.6 4.2 46.8 116.2 11.9 M M
29000 -27.0 -16.6 200 29 15 7.6 4.2 46.0 114.8 11.4 M M
28000 -24.7 -12.5 195 28 15 7.7 4.2 45.3 113.6 11.0 M M
27000 -22.4 -8.3 195 27 14 7.8 4.3 44.4 112.0 10.4 M M
26000 -20.1 -4.2 195 26 13 7.9 4.3 43.7 110.6 9.9 M M
25000 -17.9 -0.2 195 24 13 8.1 4.5 43.1 109.5 9.4 M M
24000 -15.8 3.6 200 22 12 6.6 3.6 42.0 107.6 8.6 M M
23000 -13.9 7.0 205 20 11 6.7 3.7 40.8 105.5 7.7 M M
22000 -11.9 10.6 215 19 10 6.8 3.8 39.8 103.7 6.9 M M
21000 -10.3 13.5 215 18 9 5.5 3.0 38.3 101.0 5.6 M M
20000 -8.7 16.3 215 18 9 5.5 3.0 36.8 98.3 4.3 M M
19500 -7.9 17.8 215 18 9 5.5 3.0 36.1 97.0 3.7 M M
19000 -7.1 19.2 215 18 9 5.8 3.2 35.5 95.8 3.1 M M
18500 -5.8 21.6 210 17 9 6.0 3.3 34.5 94.0 2.2 M M
18000 -4.9 23.2 210 17 9 6.1 3.4 33.9 92.9 1.6 M M
17500 -4.1 24.6 210 16 8 6.2 3.4 33.2 91.8 1.1 M M
17000 -3.2 26.2 215 15 8 6.2 3.4 32.6 90.7 0.5 M M
16500 -2.2 28.0 215 15 7 7.8 4.3 32.2 89.9 0.1 M M
16000 -1.0 30.2 225 14 7 7.7 4.2 31.8 89.3 -0.3 877 4.5
15500 0.1 32.2 230 13 7 7.7 4.2 31.5 88.6 -0.6 829 4.2
15000 1.2 34.2 240 13 7 7.6 4.2 31.1 88.0 -1.0 781 4.0
14500 2.3 36.1 245 12 6 7.2 4.0 30.8 87.4 -1.3 733 3.7
14000 3.2 37.8 255 11 6 6.7 3.7 30.3 86.5 -1.9 690 3.5
13500 4.2 39.6 265 10 5 6.5 3.6 29.8 85.6 -2.4 648 3.3
13000 5.0 41.0 280 9 5 5.7 3.1 29.1 84.5 -3.1 608 3.1
12500 5.8 42.4 295 9 5 5.7 3.1 28.5 83.3 -3.7 569 2.9
12000 6.7 44.1 310 10 5 6.6 3.6 27.9 82.3 -4.3 527 2.7
11500 7.6 45.7 325 11 6 6.6 3.6 27.4 81.4 -4.8 484 2.5
11000 8.6 47.5 330 12 6 6.6 3.6 26.9 80.5 -5.3 440 2.2
10500 9.6 49.3 335 12 6 5.7 3.1 26.5 79.6 -5.8 396 2.0
10250 10.0 50.0 340 12 6 5.3 2.9 26.1 79.0 -6.2 377 1.9
10000 10.5 50.9 340 12 6 8.1 4.4 25.8 78.5 -6.4 355 1.8
9750 11.1 52.0 345 12 6 9.2 5.0 25.8 78.4 -6.5 327 1.7
9500 11.8 53.2 345 12 6 9.0 5.0 25.7 78.3 -6.6 300 1.5
9250 12.4 54.3 350 12 6 7.1 3.9 25.6 78.1 -6.7 273 1.4
9000 12.9 55.2 350 11 6 7.3 4.0 25.4 77.7 -7.0 252 1.3
8750 13.6 56.5 350 11 6 9.2 5.1 25.3 77.5 -7.1 225 1.1
8500 14.2 57.6 350 11 6 8.5 4.7 25.2 77.4 -7.2 198 1.0
8250 14.8 58.6 350 11 6 6.9 3.8 25.1 77.1 -7.3 173 0.9
8000 15.3 59.5 345 11 5 6.2 3.4 24.8 76.7 -7.6 152 0.8
7750 15.8 60.4 345 11 6 7.2 4.0 24.6 76.2 -7.9 130 0.7
7500 16.3 61.3 345 11 6 6.1 3.4 24.4 75.9 -8.1 107 0.5
7250 16.6 61.9 345 11 6 4.0 2.2 24.0 75.2 -8.5 89 0.5
7000 16.9 62.4 345 11 6 3.8 2.1 23.5 74.4 -9.0 74 0.4
6750 17.2 63.0 345 11 6 5.7 3.1 23.1 73.7 -9.4 57 0.3
6500 17.6 63.7 350 10 5 5.8 3.2 22.9 73.2 -9.8 37 0.2
6250 17.9 64.2 350 9 5 4.9 2.7 22.5 72.5 -10.2 20 0.1
6000 18.3 64.9 355 8 4 5.3 2.9 22.2 71.9 -10.6 2 0.0
5750 18.6 65.5 355 7 3 5.5 3.0 21.8 71.3 -11.0 M M
5500 19.0 66.2 355 5 3 4.6 2.5 21.5 70.7 -11.4 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/04/2025 at 0900 MDT | 07/04/2025 at 1200 MDT
|
CAPE... +154.8 LI... -1.2 | CAPE... +326.2 LI... -2.0
CINH... -46.6 K Index... +28.5 | CINH... -5.0 K Index... +30.0
|
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 -62.3 -80.1 235 20 10 3.1 1.7 | -62.9 -81.2 220 21 11 2.9 1.6
45000 -56.3 -69.3 235 29 15 5.7 3.1 | -56.8 -70.2 230 30 16 6.2 3.4
40000 -47.6 -53.7 225 39 20 6.3 3.5 | -47.5 -53.5 230 40 21 5.9 3.3
38000 -43.8 -46.8 225 38 20 6.3 3.5 | -43.9 -47.0 235 40 21 5.9 3.3
36000 -40.1 -40.2 230 38 19 6.4 3.5 | -40.4 -40.7 240 41 21 5.9 3.2
34000 -36.4 -33.5 225 35 18 5.3 2.9 | -36.3 -33.3 240 40 21 6.0 3.3
32000 -33.2 -27.8 220 33 17 5.1 2.8 | -32.7 -26.9 240 40 20 5.8 3.2
30000 -29.2 -20.6 215 31 16 7.0 3.8 | -28.4 -19.1 240 37 19 7.4 4.1
29000 -27.1 -16.8 215 30 16 7.0 3.9 | -26.2 -15.2 240 35 18 7.4 4.1
28000 -25.0 -13.0 210 29 15 6.9 3.8 | -24.0 -11.2 245 33 17 6.1 3.3
27000 -23.1 -9.6 210 28 14 6.7 3.7 | -22.4 -8.3 245 30 16 5.2 2.9
26000 -21.1 -6.0 210 26 14 6.7 3.7 | -20.9 -5.6 240 27 14 5.3 2.9
25000 -19.1 -2.4 205 25 13 6.8 3.7 | -19.3 -2.7 240 24 13 5.2 2.9
24000 -17.0 1.4 210 23 12 6.9 3.8 | -17.4 0.7 240 23 12 6.8 3.8
23000 -15.0 5.0 215 22 11 6.9 3.8 | -15.4 4.3 245 22 11 6.9 3.8
22000 -12.9 8.8 220 20 11 6.9 3.8 | -13.4 7.9 245 21 11 6.9 3.8
21000 -11.0 12.2 225 19 10 6.5 3.6 | -11.4 11.5 250 20 10 6.8 3.8
20000 -9.2 15.4 235 17 9 6.5 3.6 | -9.4 15.1 250 18 9 6.9 3.8
19500 -8.2 17.2 235 17 9 6.6 3.6 | -8.4 16.9 255 18 9 6.9 3.8
19000 -7.3 18.9 240 16 8 6.6 3.6 | -7.4 18.7 255 17 9 6.3 3.4
18500 -6.4 20.5 245 15 8 6.6 3.6 | -6.6 20.1 260 17 9 6.2 3.4
18000 -5.0 23.0 250 15 7 6.5 3.6 | -5.7 21.7 260 17 9 6.3 3.4
17500 -4.0 24.8 255 14 7 6.5 3.6 | -4.8 23.4 265 16 8 6.4 3.5
17000 -3.1 26.4 255 14 7 6.5 3.6 | -3.5 25.7 270 16 8 6.6 3.6
16500 -2.2 28.0 260 13 7 6.5 3.6 | -2.5 27.5 270 16 8 7.1 3.9
16000 -1.3 29.7 265 13 7 6.5 3.6 | -1.5 29.3 270 15 8 7.2 3.9
15500 -0.3 31.5 270 13 7 6.5 3.6 | -0.5 31.1 275 15 8 6.5 3.6
15000 0.6 33.1 275 13 7 6.5 3.6 | 0.5 32.9 275 14 7 6.6 3.6
14500 1.5 34.7 280 13 7 6.5 3.6 | 1.4 34.5 280 14 7 6.8 3.7
14000 2.4 36.3 280 13 7 6.5 3.6 | 2.4 36.3 280 13 7 7.0 3.8
13500 3.4 38.1 285 13 7 6.7 3.6 | 3.4 38.1 280 12 6 7.2 3.9
13000 4.4 39.9 290 13 7 7.0 3.9 | 4.5 40.1 280 11 5 7.5 4.1
12500 5.4 41.7 290 13 7 7.0 3.8 | 5.5 41.9 280 10 5 7.6 4.2
12000 6.4 43.5 295 13 6 6.9 3.8 | 6.7 44.1 285 9 5 8.1 4.4
11500 7.4 45.3 295 12 6 6.9 3.8 | 7.9 46.2 285 8 4 8.1 4.5
11000 8.4 47.1 300 11 6 7.1 3.9 | 9.1 48.4 290 8 4 8.6 4.7
10500 9.4 48.9 305 10 5 4.4 2.4 | 10.4 50.7 290 7 4 3.9 2.1
10250 9.6 49.3 310 10 5 4.4 2.4 | 10.5 50.9 290 7 4 5.5 3.0
10000 10.2 50.4 310 10 5 9.5 5.2 | 11.4 52.5 295 7 3 12.9 7.1
9750 10.9 51.6 315 9 5 9.9 5.4 | 12.2 54.0 295 7 3 11.4 6.2
9500 11.6 52.9 315 8 4 9.2 5.1 | 13.0 55.4 295 6 3 10.3 5.6
9250 12.2 54.0 320 8 4 6.0 3.3 | 13.6 56.5 295 6 3 7.2 4.0
9000 12.6 54.7 315 8 4 6.7 3.7 | 14.2 57.6 295 6 3 9.7 5.3
8750 13.2 55.8 315 7 4 9.4 5.1 | 15.1 59.2 300 6 3 12.5 6.8
8500 13.9 57.0 315 6 3 8.0 4.4 | 15.9 60.6 300 5 3 10.5 5.8
8250 14.4 57.9 310 6 3 6.1 3.3 | 16.6 61.9 300 5 3 7.7 4.2
8000 14.8 58.6 310 5 3 6.5 3.5 | 17.2 63.0 300 5 2 9.2 5.1
7750 15.4 59.7 310 5 2 8.7 4.8 | 18.0 64.4 300 5 2 12.5 6.9
7500 16.0 60.8 310 4 2 7.5 4.1 | 18.9 66.0 305 4 2 10.1 5.6
7250 16.4 61.5 310 4 2 5.7 3.1 | 19.5 67.1 305 4 2 7.4 4.0
7000 16.8 62.2 315 3 1 6.5 3.6 | 20.1 68.2 305 4 2 9.1 5.0
6750 17.4 63.3 325 2 1 10.5 5.7 | 20.9 69.6 310 4 2 13.0 7.1
6500 18.3 64.9 345 1 1 10.9 6.0 | 21.9 71.4 310 3 2 11.8 6.5
6250 19.0 66.2 010 1 0 9.2 5.0 | 22.7 72.9 310 3 2 9.6 5.2
6000 19.6 67.3 050 1 0 8.9 4.9 | 23.4 74.1 315 3 2 9.1 5.0
5750 20.4 68.7 075 1 1 12.7 7.0 | 24.2 75.6 315 3 1 15.2 8.3
5500 21.7 71.1 065 1 1 22.6 12.4 | 25.9 78.6 320 3 1 30.4 16.7
07/04/2025 at 1500 MDT | 07/04/2025 at 1800 MDT
|
CAPE... +271.6 LI... -2.4 | CAPE... +272.2 LI... -2.1
CINH... -24.2 K Index... +29.5 | CINH... -29.3 K Index... +27.7
|
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 -62.8 -81.0 215 24 13 2.8 1.5 | -63.0 -81.4 210 28 14 2.8 1.5
45000 -56.8 -70.2 220 35 18 6.1 3.3 | -57.0 -70.6 220 38 20 6.2 3.4
40000 -47.7 -53.9 230 46 24 5.9 3.3 | -47.6 -53.7 230 47 24 6.2 3.4
38000 -44.1 -47.4 235 45 23 5.9 3.3 | -43.9 -47.0 235 47 24 6.2 3.4
36000 -40.1 -40.2 240 44 23 5.8 3.2 | -39.7 -39.5 245 48 25 5.8 3.2
34000 -36.8 -34.2 235 41 21 5.5 3.0 | -36.7 -34.1 245 43 22 4.9 2.7
32000 -33.5 -28.3 235 37 19 5.2 2.9 | -33.7 -28.7 240 38 20 4.7 2.6
30000 -29.2 -20.6 240 35 18 7.5 4.1 | -29.8 -21.6 240 35 18 6.8 3.7
29000 -27.0 -16.6 240 34 18 7.5 4.1 | -27.8 -18.0 245 34 18 6.8 3.7
28000 -24.7 -12.5 245 33 17 7.2 3.9 | -25.7 -14.3 245 33 17 7.1 3.9
27000 -22.6 -8.7 250 31 16 7.1 3.9 | -23.6 -10.5 250 32 16 7.2 4.0
26000 -20.5 -4.9 255 29 15 7.1 3.9 | -21.4 -6.5 255 31 16 7.2 4.0
25000 -18.4 -1.1 260 28 14 7.1 3.9 | -19.3 -2.7 255 30 15 7.2 4.0
24000 -16.6 2.1 265 26 13 5.9 3.2 | -17.2 1.0 265 28 15 6.8 3.7
23000 -14.9 5.2 270 25 13 6.0 3.3 | -15.2 4.6 270 27 14 6.8 3.7
22000 -13.2 8.2 275 24 12 6.2 3.4 | -13.2 8.2 275 26 13 6.8 3.7
21000 -11.5 11.3 275 23 12 6.0 3.3 | -11.4 11.5 280 25 13 6.3 3.5
20000 -9.7 14.5 275 22 11 6.0 3.3 | -9.6 14.7 280 25 13 6.4 3.5
19500 -8.9 16.0 275 22 11 6.0 3.3 | -8.7 16.3 280 24 13 6.5 3.6
19000 -7.5 18.5 280 21 11 7.0 3.8 | -7.7 18.1 280 24 12 7.0 3.8
18500 -6.5 20.3 280 21 11 6.9 3.8 | -6.2 20.8 285 24 12 7.0 3.9
18000 -5.5 22.1 285 20 10 7.3 4.0 | -5.2 22.6 285 23 12 7.3 4.0
17500 -4.4 24.1 285 20 10 7.4 4.1 | -4.2 24.4 285 23 12 7.3 4.0
17000 -3.3 26.1 290 19 10 7.3 4.0 | -3.1 26.4 290 22 11 7.5 4.1
16500 -2.3 27.9 290 19 10 6.9 3.8 | -2.0 28.4 290 21 11 7.9 4.3
16000 -1.3 29.7 290 19 10 6.8 3.7 | -0.8 30.6 290 21 11 7.9 4.3
15500 -0.2 31.6 295 18 9 7.7 4.2 | 0.4 32.7 295 20 10 8.6 4.7
15000 0.9 33.6 295 18 9 7.7 4.2 | 1.7 35.1 295 20 10 8.5 4.7
14500 2.0 35.6 295 17 9 8.2 4.5 | 3.0 37.4 295 19 10 8.9 4.9
14000 3.3 37.9 295 17 9 8.5 4.6 | 4.3 39.7 300 18 9 9.0 4.9
13500 4.5 40.1 300 16 8 8.6 4.7 | 5.6 42.1 300 18 9 9.0 4.9
13000 5.8 42.4 300 16 8 8.8 4.8 | 6.9 44.4 305 17 9 9.0 4.9
12500 7.1 44.8 300 15 8 8.9 4.9 | 8.2 46.8 305 17 9 9.0 5.0
12000 8.5 47.3 300 15 8 9.1 5.0 | 9.6 49.3 305 16 8 9.2 5.0
11500 9.8 49.6 305 14 7 9.0 5.0 | 11.0 51.8 305 15 8 9.1 5.0
11000 11.1 52.0 305 14 7 8.7 4.8 | 12.3 54.1 305 15 8 8.4 4.6
10500 12.4 54.3 305 13 7 4.6 2.5 | 13.5 56.3 305 14 7 4.1 2.2
10250 12.6 54.7 305 13 7 6.1 3.4 | 13.7 56.7 310 13 7 5.6 3.1
10000 13.4 56.1 305 13 6 12.8 7.0 | 14.5 58.1 310 13 7 12.6 6.9
9750 14.3 57.7 305 12 6 11.4 6.3 | 15.3 59.5 305 12 6 11.2 6.2
9500 15.1 59.2 305 12 6 10.4 5.7 | 16.1 61.0 305 12 6 9.7 5.3
9250 15.8 60.4 305 12 6 7.5 4.1 | 16.7 62.1 310 11 6 7.2 3.9
9000 16.3 61.3 305 11 6 9.1 5.0 | 17.3 63.1 310 10 5 9.5 5.2
8750 17.1 62.8 305 11 6 11.0 6.0 | 18.1 64.6 310 10 5 11.3 6.2
8500 17.9 64.2 305 10 5 9.9 5.4 | 18.9 66.0 310 10 5 9.9 5.4
8250 18.6 65.5 305 10 5 8.5 4.6 | 19.5 67.1 310 9 5 7.9 4.4
8000 19.2 66.6 305 10 5 9.1 5.0 | 20.1 68.2 310 9 5 9.1 5.0
7750 20.0 68.0 305 9 5 10.8 5.9 | 20.9 69.6 310 8 4 11.3 6.2
7500 20.7 69.3 300 9 4 9.3 5.1 | 21.7 71.1 310 8 4 9.1 5.0
7250 21.3 70.3 300 8 4 7.5 4.1 | 22.2 72.0 310 7 4 6.7 3.7
7000 21.9 71.4 300 8 4 8.5 4.7 | 22.8 73.0 315 7 4 8.3 4.6
6750 22.6 72.7 300 7 4 11.3 6.2 | 23.5 74.3 315 6 3 11.5 6.3
6500 23.5 74.3 295 6 3 10.5 5.7 | 24.4 75.9 315 5 3 10.9 6.0
6250 24.2 75.6 295 6 3 9.0 5.0 | 25.1 77.2 315 5 3 9.3 5.1
6000 24.8 76.6 290 6 3 8.4 4.6 | 25.8 78.4 315 5 3 9.3 5.1
5750 25.5 77.9 290 5 3 11.7 6.4 | 26.5 79.7 320 4 2 11.9 6.5
5500 26.7 80.1 285 5 2 22.7 12.4 | 27.7 81.9 320 4 2 18.6 10.2
________________________________________________________________________________
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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