Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
229
UXUS97 KBOU 071251
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0651 MDT Friday, June 7, 2024
This forecast is for Friday, June 7, 2024:
If the trigger temperature of 87.7 F/30.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1399 ft/min (7.1 m/s)
Maximum height of thermals.................. 19406 ft MSL (14073 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 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................. 9120 ft MSL (3787 ft AGL)
Thermal soaring outlook for Saturday 06/08..... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 34138 ft MSL (28805 ft AGL)
Wave soaring outlook for Saturday 06/08........ Poor
Remarks... A few gusty thunderstorms this afternoon, more storms likely Saturday
Sunrise/Sunset.................... 05:31:21 / 20:25:41 MDT
Total possible sunshine........... 14 hr 54 min 20 sec (894 min 20 sec)
Altitude of sun at 12:58:31 MDT... 73.08 degrees
Upper air data from numerical model forecast valid on 06/07/2024 at 0600 MDT
Freezing level.................. 16115 ft MSL (10782 ft AGL)
Convective condensation level... 17856 ft MSL (12523 ft AGL)
Lifted condensation level....... 18364 ft MSL (13031 ft AGL)
Lifted index.................... -1.6
K index......................... +15.6
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 -62.4 -80.3 270 30 15 -0.1 -0.1 M M M M M
45000 -60.8 -77.4 265 37 19 4.1 2.2 M M M M M
40000 -54.3 -65.7 250 44 22 7.2 4.0 M M M M M
38000 -49.9 -57.8 250 43 22 7.2 4.0 M M M M M
36000 -45.6 -50.1 250 42 21 7.2 3.9 M M M M M
34000 -40.3 -40.5 255 39 20 8.0 4.4 M M M M M
32000 -35.5 -31.9 260 36 18 7.9 4.3 M M M M M
30000 -30.8 -23.4 265 35 18 7.9 4.4 44.6 112.2 8.1 M M
29000 -28.4 -19.1 265 34 18 7.9 4.4 43.9 111.1 7.7 M M
28000 -26.0 -14.8 270 34 18 7.7 4.2 43.4 110.1 7.4 M M
27000 -23.8 -10.8 270 33 17 7.5 4.1 42.4 108.3 6.7 M M
26000 -21.5 -6.7 270 32 16 7.5 4.1 41.5 106.7 6.1 M M
25000 -19.3 -2.7 270 31 16 7.5 4.1 40.8 105.4 5.5 M M
24000 -17.3 0.9 270 29 15 6.2 3.4 39.5 103.1 4.5 M M
23000 -15.5 4.1 275 28 14 6.2 3.4 38.2 100.8 3.5 M M
22000 -13.7 7.3 280 27 14 6.3 3.5 37.0 98.7 2.5 M M
21000 -11.7 10.9 280 25 13 6.8 3.7 35.9 96.6 1.5 M M
20000 -9.7 14.5 280 24 13 6.8 3.7 34.8 94.7 0.6 M M
19500 -8.7 16.3 285 24 12 6.7 3.7 34.3 93.8 0.2 M M
19000 -7.6 18.3 285 23 12 7.8 4.3 33.9 93.1 -0.2 1372 7.0
18500 -5.9 21.4 285 23 12 7.9 4.3 33.4 92.2 -0.7 1297 6.6
18000 -4.7 23.5 285 23 12 8.6 4.7 33.2 91.7 -0.9 1247 6.3
17500 -3.4 25.9 285 23 12 8.8 4.8 33.0 91.4 -1.1 1193 6.1
17000 -2.1 28.2 285 23 12 8.8 4.8 32.8 91.1 -1.3 1140 5.8
16500 -0.8 30.6 280 23 12 9.0 4.9 32.7 90.9 -1.4 1085 5.5
16000 0.5 32.9 280 22 12 9.0 4.9 32.6 90.6 -1.6 1031 5.2
15500 1.9 35.4 280 22 11 9.4 5.1 32.5 90.5 -1.7 976 5.0
15000 3.3 37.9 285 21 11 9.4 5.1 32.4 90.3 -1.8 919 4.7
14500 4.6 40.3 285 20 10 9.4 5.2 32.4 90.2 -1.9 863 4.4
14000 6.0 42.8 285 19 10 9.4 5.2 32.3 90.1 -2.0 807 4.1
13500 7.4 45.3 285 18 10 9.5 5.2 32.3 90.1 -2.0 750 3.8
13000 8.8 47.8 285 18 9 9.6 5.3 32.2 90.0 -2.1 693 3.5
12500 10.3 50.5 290 17 9 9.6 5.2 32.2 90.0 -2.1 635 3.2
12000 11.7 53.1 290 16 8 9.4 5.2 32.2 89.9 -2.2 578 2.9
11500 13.1 55.6 290 15 8 9.4 5.2 32.1 89.8 -2.3 522 2.7
11000 14.3 57.7 290 14 7 8.0 4.4 31.9 89.4 -2.5 470 2.4
10500 15.5 59.9 295 13 7 11.9 6.5 31.6 88.9 -2.8 420 2.1
10250 16.5 61.7 295 13 7 12.6 6.9 32.0 89.6 -2.5 381 1.9
10000 17.2 63.0 295 13 7 7.9 4.4 31.9 89.4 -2.6 354 1.8
9750 17.8 64.0 295 13 7 9.2 5.1 31.8 89.3 -2.7 327 1.7
9500 18.5 65.3 295 13 6 8.8 4.8 31.8 89.2 -2.7 299 1.5
9250 19.1 66.4 295 12 6 7.3 4.0 31.7 89.0 -2.9 274 1.4
9000 19.6 67.3 300 11 6 7.6 4.2 31.5 88.6 -3.1 251 1.3
8750 20.3 68.5 295 11 6 8.9 4.9 31.4 88.4 -3.2 225 1.1
8500 20.9 69.6 295 11 6 8.4 4.6 31.3 88.3 -3.3 199 1.0
8250 21.4 70.5 295 11 6 6.4 3.5 31.1 88.0 -3.5 175 0.9
8000 21.8 71.2 295 11 6 4.9 2.7 30.8 87.4 -3.9 156 0.8
7750 22.1 71.8 290 11 5 5.6 3.1 30.4 86.8 -4.3 138 0.7
7500 22.5 72.5 285 11 6 4.5 2.5 30.1 86.2 -4.7 121 0.6
7250 22.7 72.9 280 11 6 2.3 1.2 29.6 85.3 -5.2 107 0.5
7000 22.8 73.0 280 10 5 0.9 0.5 29.0 84.1 -5.9 97 0.5
6750 22.8 73.0 270 10 5 0.9 0.5 28.3 82.9 -6.6 90 0.5
6500 22.7 72.9 260 10 5 -3.0 -1.6 27.5 81.5 -7.4 85 0.4
6250 22.2 72.0 250 10 5 -7.1 -3.9 26.3 79.4 -8.7 92 0.5
6000 21.7 71.1 240 10 5 -6.2 -3.4 25.1 77.2 -10.0 101 0.5
5750 21.1 70.0 230 10 5 -10.1 -5.5 23.8 74.9 -11.3 112 0.6
5500 19.8 67.6 215 9 5 -22.1 -12.1 21.9 71.4 -13.3 142 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/07/2024 at 0900 MDT | 06/07/2024 at 1200 MDT
|
CAPE... +168.1 LI... -0.3 | CAPE... +225.1 LI... -0.6
CINH... -103.2 K Index... +19.7 | CINH... -11.6 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 -62.1 -79.8 275 26 13 0.1 0.0 | -62.0 -79.6 265 22 11 0.4 0.2
45000 -60.3 -76.5 265 34 17 4.1 2.2 | -59.9 -75.8 260 30 16 3.6 2.0
40000 -53.8 -64.8 260 41 21 6.6 3.6 | -54.1 -65.4 265 42 22 6.8 3.7
38000 -49.9 -57.8 260 40 21 6.6 3.6 | -50.1 -58.2 265 42 22 6.7 3.7
36000 -45.9 -50.6 255 39 20 6.6 3.6 | -46.1 -51.0 260 42 21 6.7 3.7
34000 -40.7 -41.3 255 38 20 8.0 4.4 | -41.4 -42.5 260 42 22 8.0 4.4
32000 -35.8 -32.4 255 37 19 8.0 4.4 | -36.0 -32.8 255 42 22 8.0 4.4
30000 -31.2 -24.2 260 36 19 7.7 4.3 | -31.6 -24.9 255 38 20 7.2 4.0
29000 -28.8 -19.8 260 36 19 7.7 4.3 | -29.4 -20.9 260 36 18 7.2 4.0
28000 -26.5 -15.7 265 36 18 7.2 3.9 | -27.3 -17.1 260 33 17 6.9 3.8
27000 -24.5 -12.1 265 35 18 6.9 3.8 | -25.3 -13.5 265 33 17 6.8 3.7
26000 -22.4 -8.3 265 34 18 6.9 3.8 | -23.2 -9.8 270 32 16 6.9 3.8
25000 -20.4 -4.7 270 34 17 6.9 3.8 | -21.2 -6.2 275 32 16 7.0 3.8
24000 -18.4 -1.1 270 32 17 6.8 3.7 | -19.0 -2.2 275 31 16 7.8 4.3
23000 -16.3 2.7 275 31 16 6.9 3.8 | -16.7 1.9 275 30 16 7.8 4.3
22000 -14.3 6.3 280 29 15 7.0 3.8 | -14.4 6.1 275 30 15 7.8 4.3
21000 -12.2 10.0 285 27 14 7.4 4.1 | -12.1 10.2 275 28 14 7.9 4.3
20000 -10.0 14.0 290 24 12 7.5 4.1 | -9.8 14.4 275 26 13 7.9 4.3
19500 -8.9 16.0 295 23 12 7.4 4.1 | -8.6 16.5 275 25 13 7.9 4.3
19000 -7.7 18.1 300 22 11 8.1 4.5 | -7.5 18.5 275 24 13 8.3 4.6
18500 -6.5 20.3 300 22 11 8.2 4.5 | -6.2 20.8 275 24 12 8.4 4.6
18000 -4.7 23.5 300 22 12 8.5 4.7 | -5.0 23.0 275 23 12 8.5 4.7
17500 -3.5 25.7 300 23 12 8.6 4.7 | -3.7 25.3 280 22 12 8.9 4.9
17000 -2.2 28.0 300 24 12 8.7 4.8 | -1.7 28.9 280 22 11 9.1 5.0
16500 -0.9 30.4 300 25 13 8.9 4.9 | -0.3 31.5 280 21 11 9.4 5.1
16000 0.4 32.7 300 26 13 8.9 4.9 | 1.1 34.0 280 21 11 9.4 5.2
15500 1.7 35.1 300 26 13 9.3 5.1 | 2.5 36.5 280 21 11 9.1 5.0
15000 3.1 37.6 295 25 13 9.2 5.1 | 3.8 38.8 280 21 11 9.1 5.0
14500 4.4 39.9 295 25 13 9.3 5.1 | 5.1 41.2 285 21 11 9.2 5.1
14000 5.8 42.4 295 24 12 9.4 5.1 | 6.5 43.7 285 21 11 9.2 5.1
13500 7.2 45.0 295 23 12 9.4 5.1 | 7.9 46.2 285 20 10 9.4 5.1
13000 8.6 47.5 295 22 11 9.4 5.1 | 9.3 48.7 285 20 10 9.5 5.2
12500 10.0 50.0 295 21 11 9.4 5.1 | 10.7 51.3 285 19 10 9.5 5.2
12000 11.4 52.5 295 20 10 9.3 5.1 | 12.1 53.8 285 18 9 9.4 5.1
11500 12.8 55.0 295 19 10 9.2 5.0 | 13.5 56.3 285 17 9 9.2 5.0
11000 14.1 57.4 290 18 9 7.7 4.2 | 14.7 58.5 285 16 8 8.0 4.4
10500 15.2 59.4 290 17 9 11.6 6.4 | 15.8 60.4 290 15 8 12.2 6.7
10250 16.3 61.3 290 16 8 12.7 7.0 | 17.0 62.6 290 14 7 13.6 7.4
10000 16.9 62.4 290 16 8 8.2 4.5 | 17.7 63.9 290 14 7 8.8 4.8
9750 17.6 63.7 290 16 8 9.6 5.3 | 18.4 65.1 290 13 7 10.4 5.7
9500 18.3 64.9 290 15 8 8.6 4.7 | 19.2 66.6 290 13 7 8.6 4.7
9250 18.9 66.0 290 15 8 7.6 4.2 | 19.8 67.6 290 13 7 7.8 4.3
9000 19.5 67.1 290 15 8 8.9 4.9 | 20.4 68.7 290 13 7 10.1 5.5
8750 20.2 68.4 290 15 8 10.1 5.5 | 21.2 70.2 290 12 6 11.1 6.1
8500 21.0 69.8 285 14 7 9.4 5.2 | 22.0 71.6 290 12 6 10.4 5.7
8250 21.6 70.9 285 14 7 7.7 4.2 | 22.7 72.9 295 12 6 8.2 4.5
8000 22.1 71.8 285 14 7 7.8 4.3 | 23.4 74.1 295 12 6 9.5 5.2
7750 22.8 73.0 285 14 7 9.4 5.2 | 24.2 75.6 295 11 6 12.1 6.6
7500 23.4 74.1 280 13 7 7.6 4.2 | 25.0 77.0 295 11 6 10.3 5.7
7250 23.9 75.0 280 13 7 4.7 2.6 | 25.7 78.3 295 11 6 7.8 4.3
7000 24.1 75.4 280 12 6 4.3 2.3 | 26.3 79.3 300 11 6 8.6 4.7
6750 24.5 76.1 275 12 6 5.7 3.1 | 27.1 80.8 300 10 5 12.4 6.8
6500 24.8 76.6 275 11 6 4.8 2.6 | 28.0 82.4 300 10 5 11.7 6.4
6250 25.0 77.0 270 9 5 3.6 2.0 | 28.8 83.8 300 10 5 10.0 5.5
6000 25.3 77.5 265 7 4 3.3 1.8 | 29.5 85.1 300 9 5 9.8 5.4
5750 25.5 77.9 260 6 3 6.2 3.4 | 30.3 86.5 300 9 5 12.3 6.7
5500 26.2 79.2 250 5 3 16.0 8.8 | 31.6 88.9 300 8 4 22.6 12.4
06/07/2024 at 1500 MDT | 06/07/2024 at 1800 MDT
|
CAPE... +294.6 LI... -0.8 | CAPE... +281.5 LI... -0.7
CINH... -61.9 K Index... +26.0 | CINH... -55.7 K Index... +24.4
|
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 -61.8 -79.2 255 25 13 -0.1 -0.1 | -62.0 -79.6 260 23 12 -0.1 -0.1
45000 -60.3 -76.5 255 33 17 3.8 2.1 | -60.5 -76.9 255 30 15 3.9 2.1
40000 -54.1 -65.4 265 44 23 6.8 3.7 | -54.3 -65.7 255 41 21 7.1 3.9
38000 -50.1 -58.2 265 41 21 6.8 3.7 | -50.1 -58.2 255 39 20 7.0 3.8
36000 -46.0 -50.8 265 38 19 6.7 3.7 | -45.9 -50.6 260 37 19 7.0 3.8
34000 -40.7 -41.3 265 37 19 8.1 4.5 | -40.6 -41.1 260 36 19 8.0 4.4
32000 -35.8 -32.4 260 37 19 8.1 4.5 | -35.8 -32.4 260 36 18 8.0 4.4
30000 -31.4 -24.5 255 33 17 7.2 3.9 | -31.1 -24.0 260 36 18 7.7 4.2
29000 -29.3 -20.7 255 31 16 7.2 3.9 | -28.8 -19.8 255 35 18 7.7 4.2
28000 -27.2 -17.0 255 29 15 7.4 4.0 | -26.5 -15.7 255 35 18 7.3 4.0
27000 -25.0 -13.0 255 29 15 7.5 4.1 | -24.4 -11.9 255 34 18 7.0 3.8
26000 -22.8 -9.0 250 28 14 7.5 4.1 | -22.3 -8.1 255 33 17 7.0 3.9
25000 -20.6 -5.1 250 27 14 7.5 4.1 | -20.3 -4.5 255 32 16 7.1 3.9
24000 -18.4 -1.1 255 27 14 7.4 4.0 | -18.1 -0.6 255 31 16 7.3 4.0
23000 -16.2 2.8 255 28 14 7.4 4.1 | -15.9 3.4 260 30 16 7.4 4.0
22000 -14.1 6.6 255 28 15 7.5 4.1 | -13.8 7.2 260 29 15 7.4 4.1
21000 -11.8 10.8 255 28 14 7.9 4.3 | -11.5 11.3 265 29 15 7.9 4.3
20000 -9.5 14.9 260 28 14 7.9 4.3 | -9.1 15.6 270 29 15 7.9 4.4
19500 -8.3 17.1 260 27 14 7.9 4.3 | -8.0 17.6 270 28 15 7.9 4.4
19000 -7.1 19.2 260 27 14 8.4 4.6 | -6.8 19.8 275 28 14 8.1 4.4
18500 -5.9 21.4 260 27 14 8.4 4.6 | -5.6 21.9 275 27 14 8.1 4.4
18000 -4.0 24.8 265 26 13 8.6 4.7 | -4.4 24.1 275 27 14 8.2 4.5
17500 -2.7 27.1 265 26 13 8.7 4.8 | -2.6 27.3 280 26 14 8.5 4.6
17000 -1.5 29.3 265 25 13 8.7 4.8 | -1.4 29.5 285 26 13 8.6 4.7
16500 -0.2 31.6 270 25 13 8.9 4.9 | -0.1 31.8 285 26 13 8.8 4.8
16000 1.2 34.2 270 24 12 8.9 4.9 | 1.2 34.2 285 26 13 8.7 4.8
15500 2.5 36.5 270 23 12 9.0 4.9 | 2.5 36.5 285 25 13 9.2 5.1
15000 3.8 38.8 270 23 12 9.0 4.9 | 3.9 39.0 290 25 13 9.2 5.0
14500 5.1 41.2 275 22 12 9.0 4.9 | 5.3 41.5 290 24 13 9.3 5.1
14000 6.5 43.7 275 22 11 9.0 4.9 | 6.7 44.1 290 24 12 9.3 5.1
13500 7.8 46.0 280 22 11 9.0 5.0 | 8.1 46.6 290 23 12 9.4 5.2
13000 9.1 48.4 280 21 11 9.1 5.0 | 9.5 49.1 290 23 12 9.5 5.2
12500 10.5 50.9 280 21 11 9.2 5.0 | 10.9 51.6 290 22 11 9.6 5.2
12000 11.9 53.4 285 21 11 9.4 5.2 | 12.3 54.1 290 21 11 9.6 5.2
11500 13.3 55.9 285 20 11 9.4 5.1 | 13.7 56.7 290 21 11 9.6 5.3
11000 14.5 58.1 290 20 10 7.8 4.3 | 15.0 59.0 290 20 10 7.8 4.3
10500 15.7 60.3 290 20 10 11.6 6.4 | 16.1 61.0 290 19 10 10.7 5.8
10250 16.7 62.1 290 20 11 12.7 7.0 | 17.0 62.6 295 19 10 11.0 6.0
10000 17.4 63.3 295 21 11 8.4 4.6 | 17.6 63.7 295 19 10 7.5 4.1
9750 18.1 64.6 295 21 11 9.7 5.3 | 18.3 64.9 295 18 9 8.4 4.6
9500 18.8 65.8 295 21 11 8.9 4.9 | 18.9 66.0 295 18 9 8.2 4.5
9250 19.5 67.1 295 21 11 8.1 4.5 | 19.5 67.1 295 17 9 7.8 4.3
9000 20.1 68.2 295 22 11 9.2 5.0 | 20.0 68.0 295 15 8 7.8 4.3
8750 20.8 69.4 295 22 11 10.2 5.6 | 20.6 69.1 295 14 7 8.0 4.4
8500 21.6 70.9 300 22 11 9.9 5.4 | 21.2 70.2 295 13 7 8.0 4.4
8250 22.3 72.1 300 22 11 7.6 4.2 | 21.8 71.2 295 12 6 8.4 4.6
8000 22.8 73.0 300 22 11 8.1 4.4 | 22.4 72.3 295 11 6 8.8 4.8
7750 23.5 74.3 300 22 11 10.5 5.7 | 23.1 73.6 295 10 5 8.8 4.8
7500 24.3 75.7 300 22 11 9.0 4.9 | 23.7 74.7 295 9 5 8.7 4.8
7250 24.8 76.6 305 22 12 5.6 3.1 | 24.3 75.7 295 8 4 8.0 4.4
7000 25.2 77.4 305 23 12 5.7 3.2 | 24.9 76.8 295 8 4 8.2 4.5
6750 25.7 78.3 305 23 12 10.2 5.6 | 25.6 78.1 295 8 4 9.5 5.2
6500 26.5 79.7 305 23 12 10.3 5.6 | 26.3 79.3 295 7 3 9.6 5.3
6250 27.2 81.0 305 23 12 8.5 4.7 | 26.9 80.4 295 6 3 9.0 4.9
6000 27.8 82.0 310 22 11 8.5 4.6 | 27.6 81.7 295 6 3 9.0 4.9
5750 28.4 83.1 310 21 11 9.8 5.4 | 28.3 82.9 300 5 3 9.1 5.0
5500 29.3 84.7 310 19 10 15.4 8.5 | 29.0 84.2 295 4 2 12.2 6.7
________________________________________________________________________________
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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