Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
201
UXUS97 KBOU 080031
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1831 MDT Friday, June 7, 2024
This forecast is for Saturday, June 8, 2024:
If the trigger temperature of 78.6 F/25.9 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 334 ft/min (1.7 m/s)
Maximum height of thermals.................. 12029 ft MSL (6742 ft AGL)
Forecast maximum temperature................... 83.0 F/28.8 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ None
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................. 8744 ft MSL (3457 ft AGL)
Thermal soaring outlook for Sunday 06/09....... 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 PVA
Potential height of wave....................... 19564 ft MSL (14277 ft AGL)
Wave soaring outlook for Sunday 06/09.......... Fair
Remarks... None
Sunrise/Sunset.................... 05:31:11 / 20:26:15 MDT
Total possible sunshine........... 14 hr 55 min 4 sec (895 min 4 sec)
Altitude of sun at 12:58:43 MDT... 73.17 degrees
Upper air data from numerical model forecast valid on 06/08/2024 at 0600 MDT
Freezing level.................. 15684 ft MSL (10397 ft AGL)
Convective condensation level... 15066 ft MSL (9779 ft AGL)
Lifted condensation level....... 14243 ft MSL (8956 ft AGL)
Lifted index.................... -2.1
K index......................... +25.0
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 -60.4 -76.7 270 24 12 0.5 0.3 M M M M M
45000 -59.1 -74.4 265 33 17 1.8 1.0 M M M M M
40000 -55.8 -68.4 250 39 20 7.5 4.1 M M M M M
38000 -51.5 -60.7 250 44 23 7.1 3.9 M M M M M
36000 -47.3 -53.1 250 49 25 7.2 3.9 M M M M M
34000 -42.1 -43.8 250 51 26 9.0 5.0 M M M M M
32000 -36.7 -34.1 250 52 27 9.1 5.0 M M M M M
30000 -31.1 -24.0 255 46 24 8.0 4.4 44.6 112.4 12.4 M M
29000 -28.6 -19.5 255 41 21 8.0 4.4 44.0 111.2 12.1 M M
28000 -26.2 -15.2 255 37 19 7.4 4.1 43.5 110.3 11.8 M M
27000 -24.2 -11.6 260 35 18 6.8 3.7 42.3 108.1 11.0 M M
26000 -22.2 -8.0 260 32 17 6.9 3.8 41.1 106.0 10.2 M M
25000 -20.2 -4.4 265 30 15 7.0 3.8 40.2 104.3 9.4 M M
24000 -18.2 -0.8 265 30 15 6.8 3.7 39.0 102.2 8.6 M M
23000 -16.1 3.0 265 30 16 6.8 3.7 37.9 100.2 7.8 M M
22000 -14.1 6.6 270 31 16 6.8 3.7 36.9 98.5 7.0 M M
21000 -12.1 10.2 270 32 17 7.0 3.9 35.9 96.6 6.2 M M
20000 -10.0 14.0 275 34 17 7.1 3.9 34.9 94.8 5.4 M M
19500 -9.0 15.8 275 34 18 7.1 3.9 34.5 94.0 5.0 M M
19000 -7.9 17.8 275 35 18 8.1 4.4 34.1 93.4 4.6 M M
18500 -6.7 19.9 275 35 18 8.4 4.6 33.8 92.9 4.4 M M
18000 -5.5 22.1 275 34 18 8.4 4.6 33.6 92.5 4.2 M M
17500 -4.3 24.3 275 33 17 7.9 4.4 33.3 92.0 3.9 M M
17000 -3.2 26.2 275 31 16 8.0 4.4 33.0 91.5 3.6 M M
16500 -2.1 28.2 275 30 15 7.8 4.3 32.7 90.9 3.3 M M
16000 -1.0 30.2 275 28 14 7.7 4.2 32.4 90.3 2.9 M M
15500 0.6 33.1 275 25 13 6.9 3.8 31.8 89.3 2.4 M M
15000 1.6 34.9 275 23 12 6.8 3.7 31.3 88.4 1.9 M M
14500 2.6 36.7 280 21 11 7.1 3.9 30.9 87.5 1.5 M M
14000 3.7 38.7 285 20 10 7.4 4.1 30.5 86.8 1.1 M M
13500 4.8 40.6 285 18 9 7.6 4.2 30.1 86.2 0.8 M M
13000 6.0 42.8 290 17 9 8.1 4.4 29.8 85.6 0.5 M M
12500 7.2 45.0 295 16 8 8.0 4.4 29.5 85.1 0.2 M M
12000 8.4 47.1 295 15 8 7.8 4.3 29.2 84.6 -0.1 525 2.7
11500 9.5 49.1 295 15 8 7.8 4.3 28.9 84.0 -0.4 475 2.4
11000 10.6 51.1 295 14 7 7.0 3.8 28.5 83.4 -0.7 428 2.2
10500 11.7 53.1 290 12 6 5.2 2.9 28.1 82.7 -1.1 381 1.9
10250 12.0 53.6 290 12 6 4.9 2.7 27.7 81.9 -1.6 365 1.9
10000 12.5 54.5 285 11 5 7.8 4.3 27.5 81.4 -1.8 343 1.7
9750 13.0 55.4 280 10 5 7.6 4.2 27.3 81.1 -2.0 319 1.6
9500 13.6 56.5 270 9 4 7.6 4.1 27.1 80.8 -2.2 295 1.5
9250 14.1 57.4 260 8 4 5.5 3.0 26.9 80.4 -2.4 273 1.4
9000 14.4 57.9 250 8 4 6.2 3.4 26.6 79.8 -2.8 255 1.3
8750 15.0 59.0 240 7 4 8.1 4.4 26.4 79.5 -3.0 232 1.2
8500 15.5 59.9 230 8 4 7.5 4.1 26.2 79.2 -3.2 208 1.1
8250 16.0 60.8 220 8 4 7.0 3.9 26.0 78.9 -3.4 186 0.9
8000 16.4 61.5 215 9 4 6.6 3.6 25.8 78.5 -3.7 165 0.8
7750 16.9 62.4 210 9 5 6.7 3.7 25.6 78.0 -4.0 144 0.7
7500 17.4 63.3 210 9 5 6.1 3.4 25.3 77.6 -4.3 123 0.6
7250 17.7 63.9 210 9 5 5.4 3.0 25.0 77.0 -4.6 104 0.5
7000 18.1 64.6 210 9 5 5.0 2.7 24.7 76.4 -5.0 85 0.4
6750 18.4 65.1 210 9 5 5.0 2.8 24.3 75.8 -5.4 68 0.3
6500 18.7 65.7 210 9 4 0.5 0.3 23.8 74.9 -5.9 53 0.3
6250 18.5 65.3 210 8 4 -3.4 -1.8 22.9 73.3 -6.9 52 0.3
6000 18.3 64.9 210 7 4 -1.4 -0.8 22.0 71.6 -7.8 50 0.3
5750 18.2 64.8 210 7 3 -3.2 -1.8 21.2 70.1 -8.7 47 0.2
5500 17.6 63.7 215 6 3 -13.1 -7.2 19.9 67.7 -10.0 57 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/08/2024 at 0900 MDT | 06/08/2024 at 1200 MDT
|
CAPE... +196.3 LI... -0.7 | CAPE... +955.9 LI... -3.1
CINH... -187.0 K Index... +25.7 | CINH... -39.1 K Index... +31.3
|
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 -59.8 -75.6 265 21 11 0.4 0.2 | -58.4 -73.1 270 22 11 0.9 0.5
45000 -58.5 -73.3 255 31 16 2.1 1.1 | -57.0 -70.6 265 31 16 0.9 0.5
40000 -55.0 -67.0 245 39 20 6.9 3.8 | -55.4 -67.7 250 41 21 6.8 3.7
38000 -51.2 -60.2 245 44 23 6.4 3.5 | -51.5 -60.7 250 43 22 6.5 3.6
36000 -47.4 -53.3 245 49 25 6.4 3.5 | -47.6 -53.7 250 45 23 6.5 3.6
34000 -42.8 -45.0 250 49 25 8.1 4.4 | -42.7 -44.9 255 45 23 7.6 4.1
32000 -37.3 -35.1 250 48 25 8.0 4.4 | -38.1 -36.6 255 44 22 7.5 4.1
30000 -32.8 -27.0 250 43 22 7.5 4.1 | -33.4 -28.1 255 41 21 7.9 4.3
29000 -30.5 -22.9 250 40 21 7.5 4.1 | -31.1 -24.0 255 40 20 7.9 4.3
28000 -28.3 -18.9 250 37 19 7.4 4.1 | -28.7 -19.7 255 38 20 7.7 4.2
27000 -26.2 -15.2 250 36 19 7.2 4.0 | -26.6 -15.9 260 38 20 7.2 3.9
26000 -24.0 -11.2 250 35 18 7.2 4.0 | -24.4 -11.9 260 38 19 7.2 3.9
25000 -21.9 -7.4 255 35 18 7.2 3.9 | -22.3 -8.1 260 37 19 7.2 3.9
24000 -19.6 -3.3 255 34 18 7.9 4.3 | -20.1 -4.2 265 38 19 7.3 4.0
23000 -17.2 1.0 260 35 18 7.9 4.3 | -18.0 -0.4 265 38 20 7.4 4.1
22000 -14.9 5.2 265 35 18 8.0 4.4 | -15.8 3.6 270 38 20 7.4 4.1
21000 -12.7 9.1 265 35 18 7.3 4.0 | -13.5 7.7 270 39 20 8.1 4.5
20000 -10.6 12.9 270 34 18 7.3 4.0 | -11.1 12.0 270 40 21 8.1 4.5
19500 -9.5 14.9 270 34 17 7.3 4.0 | -9.9 14.2 270 41 21 8.1 4.5
19000 -8.5 16.7 270 34 17 7.5 4.1 | -8.7 16.3 270 41 21 8.6 4.7
18500 -7.4 18.7 270 33 17 7.6 4.2 | -7.4 18.7 270 40 21 8.8 4.8
18000 -6.3 20.7 275 33 17 7.6 4.2 | -5.5 22.1 265 40 20 8.3 4.6
17500 -4.6 23.7 275 31 16 8.1 4.4 | -4.4 24.1 265 38 20 8.1 4.4
17000 -3.4 25.9 270 31 16 8.2 4.5 | -3.2 26.2 265 37 19 8.1 4.5
16500 -2.2 28.0 270 30 15 9.0 5.0 | -2.0 28.4 265 35 18 8.4 4.6
16000 -0.9 30.4 270 29 15 9.0 4.9 | -0.8 30.6 265 33 17 8.4 4.6
15500 0.4 32.7 265 27 14 8.7 4.8 | 0.4 32.7 260 31 16 8.5 4.7
15000 1.7 35.1 265 26 14 8.7 4.8 | 1.6 34.9 260 29 15 8.6 4.7
14500 3.0 37.4 260 25 13 8.3 4.5 | 2.8 37.0 260 26 14 8.8 4.8
14000 4.2 39.6 260 24 12 7.9 4.4 | 4.2 39.6 260 24 12 8.9 4.9
13500 5.4 41.7 260 22 11 7.8 4.3 | 5.5 41.9 255 21 11 8.7 4.8
13000 6.5 43.7 255 20 10 7.4 4.0 | 6.7 44.1 255 19 10 7.9 4.4
12500 7.5 45.5 255 18 9 7.4 4.0 | 7.9 46.2 250 16 8 7.9 4.3
12000 8.6 47.5 260 16 8 7.3 4.0 | 9.0 48.2 245 14 7 6.7 3.7
11500 9.7 49.5 260 15 8 7.3 4.0 | 10.0 50.0 240 11 6 6.9 3.8
11000 10.7 51.3 265 13 7 6.5 3.6 | 10.9 51.6 230 9 4 5.7 3.1
10500 11.7 53.1 265 11 6 2.9 1.6 | 11.7 53.1 220 6 3 9.1 5.0
10250 11.8 53.2 270 11 5 3.8 2.1 | 12.5 54.5 220 5 3 10.7 5.9
10000 12.4 54.3 270 9 5 9.5 5.2 | 13.1 55.6 220 4 2 7.4 4.0
9750 12.9 55.2 265 8 4 8.0 4.4 | 13.7 56.7 215 3 2 8.3 4.6
9500 13.5 56.3 265 7 4 8.4 4.6 | 14.2 57.6 210 2 1 7.9 4.3
9250 14.1 57.4 260 6 3 6.2 3.4 | 14.8 58.6 180 1 0 7.2 3.9
9000 14.5 58.1 265 5 2 6.6 3.6 | 15.3 59.5 120 1 0 8.8 4.9
8750 15.0 59.0 260 4 2 8.5 4.7 | 16.0 60.8 085 1 0 10.5 5.7
8500 15.6 60.1 255 3 2 7.8 4.3 | 16.7 62.1 065 1 1 10.0 5.5
8250 16.1 61.0 255 2 1 6.3 3.5 | 17.4 63.3 055 2 1 9.4 5.1
8000 16.6 61.9 270 1 1 6.1 3.4 | 18.1 64.6 055 2 1 9.5 5.2
7750 17.1 62.8 290 1 1 7.6 4.2 | 18.9 66.0 055 2 1 10.3 5.6
7500 17.6 63.7 300 1 1 6.4 3.5 | 19.6 67.3 050 2 1 9.6 5.3
7250 18.0 64.4 325 2 1 4.2 2.3 | 20.3 68.5 050 2 1 8.2 4.5
7000 18.2 64.8 345 2 1 4.3 2.3 | 20.9 69.6 050 2 1 8.8 4.8
6750 18.6 65.5 355 2 1 6.7 3.7 | 21.7 71.1 045 2 1 12.1 6.6
6500 19.2 66.6 360 3 1 8.3 4.5 | 22.6 72.7 045 2 1 12.1 6.7
6250 19.8 67.6 010 3 1 8.5 4.6 | 23.4 74.1 045 3 1 10.8 5.9
6000 20.4 68.7 020 3 2 7.8 4.3 | 24.2 75.6 040 3 1 10.4 5.7
5750 21.0 69.8 025 3 2 11.1 6.1 | 25.0 77.0 040 3 1 12.6 6.9
5500 22.1 71.8 025 3 2 20.6 11.3 | 26.3 79.3 040 3 1 24.4 13.4
06/08/2024 at 1500 MDT | 06/08/2024 at 1800 MDT
|
CAPE... +1576.0 LI... -4.8 | CAPE... +1997.1 LI... -5.5
CINH... -19.0 K Index... +35.2 | CINH... -23.4 K Index... +31.4
|
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 -59.2 -74.6 270 21 11 1.3 0.7 | -59.6 -75.3 265 21 11 0.9 0.5
45000 -57.2 -71.0 260 30 16 1.2 0.7 | -58.0 -72.4 260 31 16 1.6 0.9
40000 -55.0 -67.0 260 43 22 7.0 3.8 | -54.8 -66.6 260 42 21 6.4 3.5
38000 -51.3 -60.3 265 42 22 6.3 3.5 | -50.9 -59.6 260 38 20 6.5 3.5
36000 -47.5 -53.5 270 41 21 6.4 3.5 | -47.1 -52.8 260 35 18 6.3 3.5
34000 -42.1 -43.8 270 41 21 8.5 4.7 | -42.1 -43.8 260 34 17 8.7 4.8
32000 -37.0 -34.6 275 40 21 8.4 4.6 | -36.9 -34.4 260 33 17 8.6 4.7
30000 -32.1 -25.8 275 37 19 8.0 4.4 | -31.9 -25.4 260 34 17 8.2 4.5
29000 -29.8 -21.6 275 35 18 8.0 4.4 | -29.5 -21.1 260 34 18 8.2 4.5
28000 -27.4 -17.3 275 34 17 7.7 4.2 | -27.1 -16.8 260 34 18 8.1 4.5
27000 -25.2 -13.4 275 33 17 7.1 3.9 | -24.8 -12.6 260 34 18 7.6 4.2
26000 -23.1 -9.6 270 33 17 7.2 3.9 | -22.0 -7.6 260 34 17 7.6 4.2
25000 -21.0 -5.8 270 33 17 7.3 4.0 | -19.8 -3.6 255 33 17 7.7 4.2
24000 -19.0 -2.2 265 34 18 6.4 3.5 | -17.6 0.3 255 34 18 7.4 4.1
23000 -17.1 1.2 265 36 19 6.4 3.5 | -15.4 4.3 260 35 18 7.5 4.1
22000 -15.2 4.6 260 38 20 6.2 3.4 | -13.2 8.2 260 36 18 7.3 4.0
21000 -13.0 8.6 255 38 20 8.2 4.5 | -11.2 11.8 260 35 18 6.7 3.7
20000 -10.6 12.9 255 38 20 8.3 4.6 | -9.3 15.3 260 33 17 6.8 3.7
19500 -9.4 15.1 255 38 20 8.4 4.6 | -8.3 17.1 265 32 17 6.8 3.7
19000 -8.2 17.2 255 38 19 8.3 4.5 | -7.3 18.9 265 32 16 7.3 4.0
18500 -7.1 19.2 255 36 18 8.2 4.5 | -6.2 20.8 265 31 16 7.3 4.0
18000 -5.3 22.5 255 33 17 8.2 4.5 | -5.2 22.6 270 31 16 7.3 4.0
17500 -4.1 24.6 255 31 16 8.3 4.5 | -4.1 24.6 270 30 15 7.2 3.9
17000 -2.9 26.8 255 29 15 8.3 4.5 | -3.1 26.4 270 29 15 7.2 3.9
16500 -1.7 28.9 255 27 14 8.3 4.6 | -2.1 28.2 275 28 14 7.3 4.0
16000 -0.5 31.1 255 25 13 8.3 4.6 | -1.0 30.2 275 27 14 7.4 4.1
15500 0.7 33.3 255 23 12 8.2 4.5 | 0.0 32.0 275 25 13 7.6 4.2
15000 1.9 35.4 255 21 11 8.2 4.5 | 1.2 34.2 280 24 12 7.9 4.3
14500 3.1 37.6 255 19 10 8.3 4.5 | 2.3 36.1 280 23 12 8.0 4.4
14000 4.3 39.7 250 17 9 8.3 4.6 | 3.5 38.3 280 21 11 8.2 4.5
13500 5.6 42.1 245 15 8 8.0 4.4 | 4.7 40.5 280 20 10 8.2 4.5
13000 6.6 43.9 235 13 7 6.9 3.8 | 5.9 42.6 280 18 9 8.1 4.5
12500 7.6 45.7 225 12 6 6.9 3.8 | 7.7 45.9 280 17 9 7.9 4.3
12000 8.5 47.3 210 9 5 6.3 3.5 | 8.7 47.7 280 16 8 7.0 3.9
11500 9.4 48.9 190 5 3 6.5 3.6 | 9.7 49.5 280 15 8 7.1 3.9
11000 10.2 50.4 145 2 1 5.4 3.0 | 10.8 51.4 280 15 8 6.8 3.7
10500 10.9 51.6 055 4 2 7.5 4.1 | 11.8 53.2 280 14 7 2.8 1.5
10250 11.6 52.9 045 6 3 10.2 5.6 | 11.8 53.2 280 14 7 3.5 1.9
10000 12.3 54.1 040 6 3 9.6 5.3 | 12.4 54.3 280 13 7 9.6 5.3
9750 13.0 55.4 040 7 3 9.8 5.4 | 13.0 55.4 280 12 6 8.1 4.5
9500 13.7 56.7 035 7 4 9.7 5.3 | 13.6 56.5 285 11 6 7.9 4.3
9250 14.3 57.7 035 7 4 8.6 4.7 | 14.1 57.4 285 11 5 5.6 3.1
9000 15.0 59.0 035 8 4 9.0 4.9 | 14.5 58.1 285 9 5 6.1 3.3
8750 15.7 60.3 035 8 4 10.2 5.6 | 15.0 59.0 280 8 4 7.4 4.0
8500 16.5 61.7 030 8 4 9.9 5.4 | 15.5 59.9 280 7 4 6.6 3.6
8250 17.2 63.0 030 8 4 11.4 6.3 | 15.9 60.6 280 5 3 5.1 2.8
8000 18.1 64.6 030 8 4 10.7 5.8 | 16.1 61.0 275 3 1 6.2 3.4
7750 18.8 65.8 030 8 4 8.6 4.7 | 16.6 61.9 175 1 0 8.1 4.4
7500 19.5 67.1 030 9 4 9.7 5.3 | 17.0 62.6 115 3 2 8.6 4.7
7250 20.3 68.5 025 9 4 11.5 6.3 | 17.6 63.7 110 5 2 9.3 5.1
7000 21.1 70.0 025 9 5 11.4 6.3 | 18.3 64.9 105 6 3 9.5 5.2
6750 21.9 71.4 025 9 5 8.5 4.7 | 19.0 66.2 105 7 3 10.3 5.6
6500 22.5 72.5 025 9 5 9.6 5.2 | 19.8 67.6 105 7 4 10.3 5.6
6250 23.4 74.1 025 9 5 12.3 6.7 | 20.5 68.9 105 7 4 10.1 5.5
6000 24.2 75.6 020 9 5 11.3 6.2 | 21.2 70.2 105 7 4 9.7 5.3
5750 25.1 77.2 020 9 5 12.4 6.8 | 22.0 71.6 105 7 4 12.2 6.7
5500 26.3 79.3 020 9 5 22.0 12.1 | 23.1 73.6 105 7 3 18.7 10.3
________________________________________________________________________________
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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