Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
394
UXUS97 KBOU 060028
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1827 MDT Friday, July 5, 2024
This forecast is for Saturday, July 6, 2024:
If the trigger temperature of 79.4 F/26.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1416 ft/min (7.2 m/s)
Maximum height of thermals.................. 20183 ft MSL (14885 ft AGL)
Forecast maximum temperature................... 90.0 F/32.7 C
Time of trigger temperature.................... 1100 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................. 16999 ft MSL (11701 ft AGL)
Thermal soaring outlook for Sunday 07/07....... 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....................... 46308 ft MSL (41010 ft AGL)
Wave soaring outlook for Sunday 07/07.......... Good
Remarks...
Sunrise/Sunset.................... 05:38:25 / 20:30:24 MDT
Total possible sunshine........... 14 hr 51 min 59 sec (891 min 59 sec)
Altitude of sun at 13:04:24 MDT... 72.78 degrees
Upper air data from numerical model forecast valid on 07/06/2024 at 0600 MDT
Freezing level.................. 14601 ft MSL (9303 ft AGL)
Convective condensation level... 18058 ft MSL (12760 ft AGL)
Lifted condensation level....... 19191 ft MSL (13893 ft AGL)
Lifted index.................... -0.4
K index......................... +16.6
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 -57.4 -71.3 300 36 19 2.2 1.2 M M M M M
45000 -54.7 -66.5 300 56 29 0.5 0.3 M M M M M
40000 -53.4 -64.1 300 51 26 5.5 3.0 M M M M M
38000 -50.4 -58.7 300 49 25 5.1 2.8 M M M M M
36000 -47.3 -53.1 300 47 24 5.2 2.8 M M M M M
34000 -43.3 -45.9 300 44 23 7.1 3.9 M M M M M
32000 -39.1 -38.4 300 41 21 7.2 3.9 M M M M M
30000 -34.6 -30.3 305 39 20 7.6 4.2 41.3 106.4 6.9 M M
29000 -32.3 -26.1 305 38 20 7.6 4.2 40.5 104.9 6.3 M M
28000 -29.5 -21.1 305 38 19 8.1 4.4 39.7 103.4 5.8 M M
27000 -26.9 -16.4 305 37 19 8.6 4.7 39.1 102.4 5.4 M M
26000 -24.3 -11.7 310 36 18 8.6 4.7 38.6 101.6 5.1 M M
25000 -21.8 -7.2 310 35 18 8.8 4.8 38.3 101.0 4.9 M M
24000 -19.6 -3.3 310 33 17 6.7 3.7 37.3 99.1 4.1 M M
23000 -17.6 0.3 310 31 16 6.7 3.7 36.1 97.1 3.2 M M
22000 -15.6 3.9 310 29 15 6.6 3.6 35.1 95.2 2.4 M M
21000 -14.0 6.8 305 28 15 5.5 3.0 33.6 92.5 1.1 M M
20000 -12.3 9.9 305 28 15 5.6 3.1 32.1 89.8 -0.2 1404 7.1
19500 -11.5 11.3 305 28 15 5.6 3.0 31.4 88.6 -0.8 1366 6.9
19000 -10.7 12.7 300 28 15 7.0 3.9 30.8 87.5 -1.4 1325 6.7
18500 -9.6 14.7 300 28 15 7.3 4.0 30.4 86.7 -1.8 1279 6.5
18000 -8.6 16.5 295 28 15 7.5 4.1 30.0 86.0 -2.3 1233 6.3
17500 -7.5 18.5 295 29 15 8.1 4.4 29.7 85.4 -2.6 1185 6.0
17000 -6.3 20.7 295 29 15 8.0 4.4 29.4 84.9 -2.9 1135 5.8
16500 -5.1 22.8 290 28 14 9.0 4.9 29.2 84.5 -3.2 1084 5.5
16000 -3.7 25.3 290 26 14 9.0 4.9 29.0 84.3 -3.3 1028 5.2
15500 -2.4 27.7 290 25 13 8.4 4.6 28.9 84.1 -3.4 973 4.9
15000 -1.2 29.8 290 23 12 7.9 4.4 28.6 83.5 -3.8 924 4.7
14500 0.5 32.9 285 19 10 8.7 4.8 28.2 82.7 -4.2 848 4.3
14000 1.9 35.4 290 17 9 8.9 4.9 28.0 82.5 -4.4 794 4.0
13500 3.2 37.8 290 15 8 9.0 5.0 27.9 82.2 -4.5 739 3.8
13000 4.5 40.1 295 15 8 9.1 5.0 27.8 82.0 -4.6 684 3.5
12500 5.9 42.6 300 14 7 9.1 5.0 27.7 81.9 -4.7 628 3.2
12000 7.3 45.1 300 15 8 9.1 5.0 27.6 81.7 -4.9 573 2.9
11500 8.6 47.5 305 16 8 9.1 5.0 27.5 81.5 -5.0 518 2.6
11000 9.9 49.8 310 15 8 8.7 4.8 27.4 81.3 -5.2 463 2.4
10500 11.3 52.3 315 14 7 4.8 2.6 27.3 81.1 -5.3 408 2.1
10250 11.5 52.7 315 14 7 6.4 3.5 26.8 80.2 -5.8 394 2.0
10000 12.4 54.3 315 15 8 12.7 7.0 26.9 80.4 -5.7 361 1.8
9750 13.2 55.8 320 16 8 11.7 6.4 27.0 80.7 -5.6 329 1.7
9500 14.0 57.2 320 17 9 9.7 5.3 27.2 80.9 -5.5 296 1.5
9250 14.6 58.3 320 17 9 6.2 3.4 27.0 80.6 -5.7 272 1.4
9000 15.1 59.2 320 17 9 8.3 4.5 26.8 80.2 -5.9 250 1.3
8750 15.8 60.4 320 18 9 9.9 5.4 26.8 80.2 -6.0 221 1.1
8500 16.5 61.7 320 18 9 9.3 5.1 26.7 80.1 -6.0 192 1.0
8250 17.2 63.0 320 19 10 9.5 5.2 26.7 80.1 -6.1 164 0.8
8000 17.9 64.2 315 20 10 8.7 4.8 26.7 80.0 -6.1 136 0.7
7750 18.5 65.3 315 20 11 7.6 4.2 26.5 79.8 -6.2 110 0.6
7500 19.1 66.4 310 21 11 7.8 4.3 26.4 79.5 -6.4 86 0.4
7250 19.7 67.5 310 22 11 7.7 4.2 26.2 79.2 -6.6 60 0.3
7000 20.3 68.5 305 23 12 8.7 4.8 26.1 79.0 -6.7 35 0.2
6750 20.9 69.6 305 23 12 6.5 3.6 26.0 78.8 -6.8 9 0.0
6500 21.1 70.0 300 22 11 -1.3 -0.7 25.5 77.8 -7.4 M M
6250 20.7 69.3 295 19 10 -6.5 -3.5 24.4 75.9 -8.5 M M
6000 20.4 68.7 290 17 9 0.8 0.5 23.3 74.0 -9.6 3 0.0
5750 20.5 68.9 285 15 7 -6.6 -3.6 22.7 72.8 -10.2 M M
5500 18.6 65.5 270 9 5 -38.7 -21.2 20.3 68.5 -12.8 40 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/06/2024 at 0900 MDT | 07/06/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.3 | CAPE... 0.0 LI... +1.6
CINH... 0.0 K Index... +15.6 | CINH... 0.0 K Index... +5.6
|
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 -57.3 -71.1 295 33 17 2.4 1.3 | -57.9 -72.2 290 40 20 2.2 1.2
45000 -54.3 -65.7 305 54 28 0.9 0.5 | -54.9 -66.8 300 56 29 1.4 0.8
40000 -52.6 -62.7 305 56 29 4.2 2.3 | -52.4 -62.3 305 61 31 4.3 2.3
38000 -50.2 -58.4 305 52 27 3.9 2.1 | -50.0 -58.0 305 57 29 4.0 2.2
36000 -47.9 -54.2 300 48 25 4.0 2.2 | -47.5 -53.5 300 53 27 4.1 2.3
34000 -44.0 -47.2 300 46 24 7.5 4.1 | -43.8 -46.8 300 49 25 7.2 3.9
32000 -39.6 -39.3 305 44 23 7.5 4.1 | -39.5 -39.1 295 46 24 7.2 3.9
30000 -34.7 -30.5 305 41 21 8.4 4.6 | -34.6 -30.3 295 44 23 8.7 4.8
29000 -31.5 -24.7 305 39 20 8.4 4.6 | -31.3 -24.3 295 43 22 8.7 4.8
28000 -29.0 -20.2 305 38 20 8.3 4.5 | -28.7 -19.7 295 43 22 8.2 4.5
27000 -26.6 -15.9 305 36 19 8.1 4.4 | -26.4 -15.5 295 41 21 7.6 4.2
26000 -24.2 -11.6 305 34 18 8.1 4.4 | -24.1 -11.4 295 39 20 7.6 4.2
25000 -21.8 -7.2 305 32 17 8.2 4.5 | -21.8 -7.2 290 37 19 7.6 4.2
24000 -19.5 -3.1 305 31 16 7.5 4.1 | -19.5 -3.1 290 34 18 7.6 4.2
23000 -17.2 1.0 305 29 15 7.5 4.1 | -17.3 0.9 290 32 16 7.7 4.2
22000 -15.0 5.0 300 28 14 7.5 4.1 | -15.0 5.0 290 29 15 7.6 4.2
21000 -13.3 8.1 300 27 14 5.4 3.0 | -13.0 8.6 290 28 14 6.2 3.4
20000 -11.7 10.9 300 26 13 5.4 3.0 | -11.2 11.8 290 26 13 6.2 3.4
19500 -10.9 12.4 295 25 13 5.4 3.0 | -10.2 13.6 290 25 13 6.3 3.4
19000 -10.1 13.8 295 25 13 5.5 3.0 | -9.3 15.3 290 25 13 5.9 3.2
18500 -9.3 15.3 295 25 13 5.6 3.1 | -8.4 16.9 290 25 13 5.9 3.2
18000 -8.5 16.7 290 25 13 5.9 3.2 | -7.6 18.3 290 25 13 6.0 3.3
17500 -7.5 18.5 290 25 13 7.4 4.1 | -6.6 20.1 290 25 13 6.8 3.8
17000 -6.4 20.5 285 24 13 7.3 4.0 | -5.6 21.9 285 26 13 6.8 3.7
16500 -5.4 22.3 285 24 12 7.8 4.3 | -4.6 23.7 285 26 14 6.9 3.8
16000 -4.3 24.3 285 24 12 8.0 4.4 | -3.6 25.5 285 27 14 7.0 3.8
15500 -2.4 27.7 285 24 12 9.3 5.1 | -2.6 27.3 285 27 14 7.6 4.1
15000 -1.1 30.0 285 24 12 9.2 5.1 | -0.8 30.6 285 27 14 8.3 4.6
14500 0.3 32.5 285 24 12 8.8 4.8 | 0.4 32.7 285 27 14 8.8 4.8
14000 1.6 34.9 285 24 12 8.6 4.7 | 1.7 35.1 285 26 13 8.9 4.9
13500 2.8 37.0 285 24 12 8.6 4.7 | 3.0 37.4 285 25 13 8.6 4.7
13000 4.1 39.4 285 24 12 8.6 4.7 | 4.2 39.6 290 23 12 8.2 4.5
12500 5.4 41.7 285 24 12 8.4 4.6 | 5.4 41.7 290 22 11 8.3 4.5
12000 6.5 43.7 285 23 12 7.9 4.4 | 6.7 44.1 290 20 10 8.6 4.7
11500 7.7 45.9 290 22 11 8.1 4.4 | 7.9 46.2 290 18 9 8.4 4.6
11000 8.9 48.0 290 20 10 8.3 4.5 | 9.1 48.4 290 16 8 7.6 4.2
10500 10.2 50.4 295 18 9 5.1 2.8 | 10.2 50.4 290 14 7 4.0 2.2
10250 10.4 50.7 300 17 9 4.7 2.6 | 10.4 50.7 290 13 7 4.3 2.4
10000 11.0 51.8 300 17 9 10.2 5.6 | 11.0 51.8 295 12 6 9.8 5.4
9750 11.8 53.2 300 16 8 10.8 5.9 | 11.6 52.9 300 10 5 9.0 4.9
9500 12.5 54.5 300 16 8 9.0 4.9 | 12.3 54.1 305 8 4 8.6 4.7
9250 13.1 55.6 305 15 8 5.7 3.1 | 12.8 55.0 315 7 3 7.4 4.0
9000 13.5 56.3 310 15 7 6.7 3.7 | 13.3 55.9 325 5 3 8.0 4.4
8750 14.1 57.4 310 14 7 8.6 4.7 | 13.9 57.0 350 4 2 8.5 4.6
8500 14.6 58.3 315 13 7 6.7 3.7 | 14.5 58.1 015 4 2 8.9 4.9
8250 15.0 59.0 315 13 6 4.8 2.6 | 15.2 59.4 020 4 2 9.7 5.3
8000 15.4 59.7 320 12 6 5.1 2.8 | 15.9 60.6 025 4 2 9.5 5.2
7750 15.8 60.4 320 11 6 5.7 3.1 | 16.6 61.9 030 5 2 9.3 5.1
7500 16.2 61.2 325 10 5 4.0 2.2 | 17.3 63.1 030 5 2 9.9 5.4
7250 16.4 61.5 330 10 5 2.5 1.4 | 18.0 64.4 030 5 2 10.4 5.7
7000 16.6 61.9 340 10 5 2.7 1.5 | 18.8 65.8 030 5 2 10.2 5.6
6750 16.8 62.2 345 11 6 3.1 1.7 | 19.5 67.1 035 5 2 10.5 5.7
6500 17.0 62.6 350 10 5 4.5 2.5 | 20.3 68.5 035 5 2 10.8 5.9
6250 17.4 63.3 360 9 4 5.9 3.3 | 21.2 70.2 035 5 2 11.7 6.4
6000 17.7 63.9 010 7 4 2.8 1.5 | 22.0 71.6 035 5 2 9.0 5.0
5750 18.0 64.4 025 6 3 9.7 5.3 | 22.7 72.9 035 5 2 15.3 8.4
5500 19.5 67.1 025 5 3 29.7 16.3 | 24.6 76.3 035 5 2 33.9 18.6
07/06/2024 at 1500 MDT | 07/06/2024 at 1800 MDT
|
CAPE... +17.3 LI... -0.2 | CAPE... +127.5 LI... -0.7
CINH... -16.0 K Index... +18.0 | CINH... -38.7 K Index... +22.5
|
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 -57.7 -71.9 290 43 22 2.8 1.5 | -57.5 -71.5 290 39 20 3.4 1.9
45000 -54.2 -65.6 300 57 29 0.8 0.5 | -53.4 -64.1 300 52 27 0.7 0.4
40000 -52.6 -62.7 305 65 34 4.5 2.5 | -52.0 -61.6 300 71 36 4.2 2.3
38000 -50.1 -58.2 305 63 33 4.2 2.3 | -49.7 -57.5 305 71 37 3.9 2.1
36000 -47.5 -53.5 305 61 31 4.3 2.3 | -47.4 -53.3 305 71 37 3.9 2.2
34000 -43.8 -46.8 300 57 29 7.0 3.9 | -43.8 -46.8 305 68 35 6.8 3.7
32000 -39.6 -39.3 300 52 27 7.1 3.9 | -39.7 -39.5 305 63 32 6.8 3.8
30000 -34.8 -30.6 295 49 25 8.6 4.7 | -35.2 -31.4 300 57 29 7.8 4.3
29000 -32.2 -26.0 295 48 25 8.6 4.7 | -32.3 -26.1 295 54 28 7.9 4.3
28000 -29.0 -20.2 295 47 24 8.4 4.6 | -30.0 -22.0 295 51 26 7.8 4.3
27000 -26.6 -15.9 295 46 24 8.1 4.4 | -27.7 -17.9 295 49 25 7.7 4.2
26000 -24.1 -11.4 295 45 23 8.1 4.4 | -25.4 -13.7 295 47 24 7.7 4.2
25000 -21.7 -7.1 295 44 23 8.3 4.6 | -23.1 -9.6 295 46 23 7.8 4.3
24000 -19.7 -3.5 290 42 22 6.1 3.3 | -21.1 -6.0 290 42 22 6.1 3.3
23000 -17.9 -0.2 285 40 21 6.1 3.3 | -19.3 -2.7 285 39 20 6.1 3.4
22000 -16.1 3.0 280 38 20 6.1 3.4 | -17.5 0.5 285 35 18 6.2 3.4
21000 -14.1 6.6 280 37 19 6.9 3.8 | -15.1 4.8 280 34 18 8.6 4.7
20000 -12.0 10.4 275 35 18 7.0 3.8 | -12.6 9.3 275 33 17 8.7 4.8
19500 -11.0 12.2 275 34 18 7.0 3.8 | -11.4 11.5 270 33 17 8.8 4.8
19000 -10.0 14.0 275 34 17 7.1 3.9 | -10.2 13.6 270 33 17 8.7 4.8
18500 -9.0 15.8 270 33 17 7.2 3.9 | -8.9 16.0 270 32 16 8.7 4.8
18000 -8.0 17.6 270 33 17 7.6 4.2 | -7.6 18.3 270 30 16 8.7 4.8
17500 -6.7 19.9 270 32 17 9.1 5.0 | -6.4 20.5 270 29 15 8.7 4.8
17000 -5.4 22.3 270 31 16 9.1 5.0 | -5.1 22.8 275 27 14 8.7 4.8
16500 -4.1 24.6 270 30 16 8.5 4.7 | -3.8 25.2 275 25 13 9.2 5.0
16000 -2.9 26.8 270 29 15 8.5 4.7 | -2.4 27.7 275 24 12 9.2 5.1
15500 -1.6 29.1 270 27 14 8.6 4.7 | -1.0 30.2 275 22 11 9.1 5.0
15000 -0.4 31.3 270 25 13 8.6 4.7 | 1.0 33.8 275 19 10 8.8 4.9
14500 1.6 34.9 270 23 12 8.9 4.9 | 2.3 36.1 275 18 9 9.1 5.0
14000 2.9 37.2 270 21 11 9.0 4.9 | 3.6 38.5 275 16 8 9.1 5.0
13500 4.2 39.6 270 19 10 8.7 4.8 | 5.0 41.0 275 14 7 8.9 4.9
13000 5.5 41.9 270 16 8 8.5 4.6 | 6.3 43.3 275 11 6 8.6 4.7
12500 6.7 44.1 270 13 7 8.3 4.5 | 7.6 45.7 270 9 5 8.7 4.8
12000 7.9 46.2 270 10 5 7.8 4.3 | 8.9 48.0 270 7 4 8.8 4.8
11500 9.0 48.2 270 6 3 7.9 4.3 | 10.2 50.4 270 6 3 8.7 4.8
11000 10.2 50.4 270 3 2 7.8 4.3 | 11.4 52.5 270 4 2 8.2 4.5
10500 11.3 52.3 280 2 1 4.0 2.2 | 12.7 54.9 265 3 2 5.2 2.8
10250 11.5 52.7 285 1 1 5.9 3.2 | 12.9 55.2 265 3 1 6.3 3.5
10000 12.3 54.1 295 1 0 12.3 6.8 | 13.7 56.7 265 2 1 11.3 6.2
9750 13.1 55.6 310 1 0 10.7 5.9 | 14.4 57.9 270 2 1 10.1 5.5
9500 13.9 57.0 325 1 0 10.7 5.9 | 15.2 59.4 275 2 1 10.0 5.5
9250 14.6 58.3 330 1 0 9.8 5.4 | 15.9 60.6 275 1 1 9.2 5.0
9000 15.4 59.7 335 1 0 10.2 5.6 | 16.6 61.9 280 1 1 9.9 5.4
8750 16.2 61.2 340 1 0 10.6 5.8 | 17.3 63.1 285 1 1 10.4 5.7
8500 16.9 62.4 345 1 0 10.3 5.6 | 18.1 64.6 285 1 1 10.1 5.5
8250 17.7 63.9 345 1 1 10.1 5.5 | 18.8 65.8 290 1 1 9.8 5.4
8000 18.4 65.1 345 1 1 9.7 5.3 | 19.6 67.3 290 1 1 9.7 5.3
7750 19.1 66.4 345 1 1 9.0 4.9 | 20.3 68.5 295 2 1 9.4 5.1
7500 19.8 67.6 350 1 1 10.1 5.5 | 21.0 69.8 295 2 1 10.0 5.5
7250 20.6 69.1 350 1 1 11.2 6.1 | 21.8 71.2 295 2 1 10.9 6.0
7000 21.5 70.7 350 1 1 10.6 5.8 | 22.6 72.7 300 2 1 10.5 5.8
6750 22.2 72.0 350 1 1 10.1 5.6 | 23.3 73.9 300 2 1 9.5 5.2
6500 23.0 73.4 350 1 1 10.4 5.7 | 24.0 75.2 300 2 1 9.9 5.5
6250 23.8 74.8 350 1 1 11.4 6.3 | 24.8 76.6 300 2 1 10.9 6.0
6000 24.6 76.3 345 1 1 9.4 5.1 | 25.6 78.1 300 2 1 10.0 5.5
5750 25.4 77.7 345 1 1 14.8 8.1 | 26.4 79.5 305 2 1 12.2 6.7
5500 27.1 80.8 350 2 1 31.1 17.1 | 27.6 81.7 305 2 1 19.8 10.9
________________________________________________________________________________
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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