Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
608
UXUS97 KBOU 040011
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1810 MDT Wednesday, July 3, 2024
This forecast is for Thursday, July 4, 2024:
If the trigger temperature of 64.3 F/17.9 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 538 ft/min (2.7 m/s)
Maximum height of thermals.................. 13813 ft MSL (8507 ft AGL)
Forecast maximum temperature................... 82.0 F/28.2 C
Time of trigger temperature.................... 0915 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................. 11453 ft MSL (6147 ft AGL)
Thermal soaring outlook for Friday 07/05....... Poor
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)................ Neither
Potential height of wave....................... 17130 ft MSL (11824 ft AGL)
Wave soaring outlook for Friday 07/05.......... Good
Remarks...
Sunrise/Sunset.................... 05:37:13 / 20:30:55 MDT
Total possible sunshine........... 14 hr 53 min 42 sec (893 min 42 sec)
Altitude of sun at 13:04:04 MDT... 72.99 degrees
Upper air data from numerical model forecast valid on 07/04/2024 at 0600 MDT
Freezing level.................. 14978 ft MSL (9672 ft AGL)
Convective condensation level... 16853 ft MSL (11547 ft AGL)
Lifted condensation level....... 15534 ft MSL (10228 ft AGL)
Lifted index.................... +1.1
K index......................... -13.4
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 -59.7 -75.5 275 40 20 2.1 1.2 M M M M M
45000 -55.8 -68.4 280 63 33 3.7 2.1 M M M M M
40000 -49.8 -57.6 270 71 37 5.9 3.3 M M M M M
38000 -46.2 -51.2 275 71 36 6.0 3.3 M M M M M
36000 -42.6 -44.7 275 71 36 6.0 3.3 M M M M M
34000 -38.4 -37.1 275 70 36 6.3 3.4 M M M M M
32000 -34.7 -30.5 280 70 36 6.2 3.4 M M M M M
30000 -30.1 -22.2 280 69 36 7.9 4.3 46.7 116.1 14.4 M M
29000 -27.7 -17.9 280 69 36 7.9 4.3 46.0 114.9 14.0 M M
28000 -25.4 -13.7 285 69 36 7.4 4.1 45.5 113.8 13.8 M M
27000 -23.4 -10.1 285 67 35 6.7 3.7 44.2 111.5 12.9 M M
26000 -21.4 -6.5 285 65 33 6.7 3.7 43.0 109.4 12.1 M M
25000 -19.4 -2.9 285 63 32 6.9 3.8 41.9 107.5 11.4 M M
24000 -18.0 -0.4 285 59 30 3.6 2.0 40.0 103.9 9.9 M M
23000 -16.9 1.6 285 54 28 3.6 2.0 37.7 99.8 8.1 M M
22000 -15.8 3.6 285 49 25 3.2 1.8 35.6 96.0 6.4 M M
21000 -13.9 7.0 285 46 24 7.5 4.1 34.3 93.8 5.5 M M
20000 -11.7 10.9 285 44 23 7.4 4.1 33.5 92.3 4.8 M M
19500 -10.5 13.1 285 43 22 7.4 4.1 33.1 91.6 4.6 M M
19000 -9.4 15.1 285 42 22 8.9 4.9 32.8 91.1 4.3 M M
18500 -7.9 17.8 285 41 21 9.4 5.2 32.8 91.0 4.3 M M
18000 -6.5 20.3 290 40 21 9.4 5.2 32.7 90.9 4.3 M M
17500 -5.2 22.6 290 40 21 7.8 4.3 32.5 90.5 4.1 M M
17000 -3.5 25.7 295 42 21 7.7 4.2 32.1 89.7 3.7 M M
16500 -2.4 27.7 295 41 21 6.1 3.3 31.5 88.8 3.3 M M
16000 -1.5 29.3 290 39 20 6.3 3.4 30.9 87.7 2.8 M M
15500 -0.6 30.9 290 37 19 5.1 2.8 30.3 86.5 2.2 M M
15000 0.1 32.2 285 36 18 5.1 2.8 29.5 85.1 1.5 M M
14500 0.8 33.4 285 34 18 5.6 3.1 28.7 83.7 0.8 M M
14000 1.7 35.1 285 32 17 6.0 3.3 28.1 82.6 0.1 M M
13500 2.5 36.5 285 30 16 6.4 3.5 27.5 81.5 -0.5 507 2.6
13000 3.5 38.3 285 28 14 6.9 3.8 27.0 80.6 -1.0 464 2.4
12500 4.4 39.9 280 26 13 6.6 3.6 26.6 79.8 -1.5 420 2.1
12000 5.2 41.4 285 24 12 5.2 2.8 25.9 78.6 -2.2 382 1.9
11500 5.9 42.6 285 21 11 4.5 2.5 25.2 77.3 -3.0 346 1.8
11000 6.1 43.0 285 18 9 0.3 0.2 23.9 75.0 -4.3 325 1.7
10500 6.1 43.0 290 15 8 0.4 0.2 22.5 72.4 -5.7 310 1.6
10250 6.1 43.0 290 14 7 -0.4 -0.2 21.7 71.1 -6.5 304 1.5
10000 6.0 42.8 290 13 7 -0.5 -0.3 20.9 69.6 -7.3 298 1.5
9750 5.9 42.6 300 10 5 -0.8 -0.5 20.1 68.1 -8.2 294 1.5
9500 5.8 42.4 315 7 4 1.0 0.6 19.3 66.7 -9.0 289 1.5
9250 6.0 42.8 330 6 3 3.7 2.0 18.7 65.7 -9.6 276 1.4
9000 6.4 43.5 345 7 3 5.3 2.9 18.3 65.0 -10.0 259 1.3
8750 6.9 44.4 355 8 4 7.2 4.0 18.1 64.5 -10.3 236 1.2
8500 7.4 45.3 005 9 5 7.0 3.9 17.9 64.2 -10.4 212 1.1
8250 7.9 46.2 010 10 5 6.5 3.5 17.6 63.7 -10.7 190 1.0
8000 8.4 47.1 010 10 5 6.8 3.7 17.4 63.3 -11.0 168 0.9
7750 8.9 48.0 015 11 6 7.0 3.8 17.2 62.9 -11.2 145 0.7
7500 9.4 48.9 015 11 6 5.1 2.8 16.9 62.4 -11.5 124 0.6
7250 9.6 49.3 015 11 6 3.9 2.1 16.5 61.6 -12.0 109 0.6
7000 9.9 49.8 015 11 6 4.0 2.2 16.0 60.9 -12.5 93 0.5
6750 10.2 50.4 015 11 6 4.9 2.7 15.6 60.1 -13.0 77 0.4
6500 10.6 51.1 005 9 5 6.3 3.5 15.3 59.6 -13.4 58 0.3
6250 11.0 51.8 350 7 4 5.9 3.2 15.0 59.1 -13.7 39 0.2
6000 11.4 52.5 325 6 3 7.4 4.1 14.8 58.6 -14.1 19 0.1
5750 12.0 53.6 305 6 3 8.9 4.9 14.7 58.4 -14.3 M M
5500 12.6 54.7 290 5 2 6.8 3.7 14.6 58.2 -14.5 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/04/2024 at 0900 MDT | 07/04/2024 at 1200 MDT
|
CAPE... 0.0 LI... +3.9 | CAPE... 0.0 LI... +2.6
CINH... -0.0 K Index... -7.1 | CINH... -0.2 K Index... +3.3
|
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 -59.9 -75.8 280 40 20 2.4 1.3 | -59.5 -75.1 285 39 20 2.5 1.4
45000 -55.4 -67.7 280 60 31 3.9 2.1 | -55.1 -67.2 285 58 30 3.7 2.1
40000 -49.4 -56.9 270 67 35 5.2 2.8 | -49.3 -56.7 275 68 35 4.9 2.7
38000 -46.3 -51.3 270 66 34 5.2 2.8 | -46.3 -51.3 275 68 35 4.9 2.7
36000 -43.2 -45.8 270 66 34 5.2 2.9 | -43.4 -46.1 275 69 36 4.9 2.7
34000 -39.5 -39.1 270 65 34 6.4 3.5 | -39.3 -38.7 275 68 35 6.3 3.5
32000 -35.2 -31.4 275 65 34 6.4 3.5 | -35.5 -31.9 275 67 34 6.3 3.4
30000 -30.8 -23.4 275 66 34 7.4 4.0 | -31.2 -24.2 275 66 34 7.5 4.1
29000 -28.6 -19.5 280 66 34 7.4 4.0 | -28.9 -20.0 275 65 34 7.5 4.1
28000 -26.4 -15.5 280 67 34 7.5 4.1 | -26.7 -16.1 275 65 33 7.4 4.1
27000 -24.1 -11.4 280 66 34 7.7 4.2 | -24.5 -12.1 280 64 33 7.2 4.0
26000 -21.8 -7.2 280 65 33 7.7 4.2 | -22.3 -8.1 280 63 33 7.2 4.0
25000 -19.5 -3.1 285 64 33 8.0 4.4 | -20.2 -4.4 280 63 32 7.4 4.1
24000 -17.8 -0.0 285 60 31 5.0 2.7 | -18.4 -1.1 280 60 31 5.2 2.9
23000 -16.3 2.7 285 55 28 5.0 2.7 | -16.8 1.8 285 56 29 5.2 2.9
22000 -14.8 5.4 285 50 26 4.9 2.7 | -15.3 4.5 285 51 26 5.2 2.8
21000 -13.1 8.4 285 47 24 6.0 3.3 | -13.5 7.7 285 48 25 5.9 3.2
20000 -11.3 11.7 285 44 23 6.0 3.3 | -11.8 10.8 285 45 23 5.9 3.2
19500 -10.4 13.3 285 43 22 6.0 3.3 | -10.9 12.4 290 44 22 5.9 3.2
19000 -9.5 14.9 285 41 21 6.6 3.6 | -10.0 14.0 290 42 22 6.6 3.6
18500 -8.5 16.7 290 40 21 6.8 3.7 | -9.0 15.8 290 41 21 6.8 3.7
18000 -7.4 18.7 290 40 20 6.8 3.7 | -7.5 18.5 290 40 21 7.2 3.9
17500 -5.9 21.4 290 38 20 7.2 4.0 | -6.4 20.5 285 39 20 7.3 4.0
17000 -4.8 23.4 290 37 19 7.1 3.9 | -5.3 22.5 285 38 19 7.3 4.0
16500 -3.8 25.2 290 35 18 6.6 3.6 | -4.2 24.4 285 37 19 7.0 3.8
16000 -2.8 27.0 290 34 18 6.7 3.7 | -3.2 26.2 285 36 18 7.1 3.9
15500 -1.8 28.8 290 33 17 5.7 3.1 | -2.2 28.0 285 34 18 6.6 3.6
15000 -1.0 30.2 295 32 16 5.7 3.1 | -1.2 29.8 285 33 17 6.7 3.7
14500 -0.1 31.8 295 31 16 6.1 3.3 | -0.2 31.6 280 32 17 6.5 3.5
14000 0.8 33.4 295 29 15 6.3 3.5 | 0.7 33.3 280 31 16 6.5 3.5
13500 1.7 35.1 295 28 14 6.4 3.5 | 1.6 34.9 280 30 15 6.9 3.8
13000 2.6 36.7 295 26 14 6.4 3.5 | 2.6 36.7 280 27 14 7.3 4.0
12500 3.6 38.5 295 25 13 6.4 3.5 | 3.7 38.7 280 25 13 7.5 4.1
12000 4.5 40.1 295 23 12 6.4 3.5 | 4.8 40.6 280 23 12 7.9 4.3
11500 5.4 41.7 295 21 11 6.3 3.5 | 5.9 42.6 280 20 10 7.7 4.2
11000 6.2 43.2 295 18 9 5.9 3.2 | 7.0 44.6 280 16 8 7.0 3.8
10500 7.0 44.6 295 16 8 4.5 2.5 | 8.0 46.4 285 13 7 4.1 2.2
10250 7.2 45.0 295 15 8 2.0 1.1 | 8.1 46.6 285 12 6 2.4 1.3
10000 7.4 45.3 295 14 7 4.7 2.6 | 8.5 47.3 290 11 5 7.8 4.3
9750 7.9 46.2 300 12 6 7.2 4.0 | 9.2 48.6 295 9 5 9.8 5.4
9500 8.3 46.9 300 10 5 4.8 2.6 | 9.8 49.6 305 7 4 7.2 4.0
9250 8.5 47.3 305 9 5 1.6 0.9 | 10.2 50.4 315 6 3 3.8 2.1
9000 8.6 47.5 305 8 4 2.8 1.5 | 10.5 50.9 325 4 2 6.0 3.3
8750 8.9 48.0 310 6 3 4.8 2.6 | 11.0 51.8 350 3 2 8.1 4.5
8500 9.1 48.4 315 5 2 3.9 2.1 | 11.6 52.9 025 3 2 7.4 4.1
8250 9.3 48.7 320 4 2 2.8 1.5 | 12.1 53.8 035 3 2 6.8 3.7
8000 9.5 49.1 330 3 1 4.0 2.2 | 12.6 54.7 045 4 2 8.6 4.7
7750 9.9 49.8 350 2 1 6.5 3.6 | 13.3 55.9 045 4 2 11.4 6.2
7500 10.4 50.7 005 2 1 6.6 3.6 | 14.1 57.4 045 4 2 9.7 5.3
7250 10.8 51.4 020 2 1 5.2 2.8 | 14.8 58.6 045 4 2 7.6 4.2
7000 11.2 52.2 030 2 1 7.1 3.9 | 15.4 59.7 050 4 2 9.9 5.5
6750 11.8 53.2 040 3 1 11.5 6.3 | 16.3 61.3 050 4 2 13.0 7.1
6500 12.7 54.9 040 3 1 11.4 6.3 | 17.2 63.0 045 4 2 11.6 6.4
6250 13.4 56.1 045 3 1 10.2 5.6 | 18.0 64.4 045 4 2 10.6 5.8
6000 14.2 57.6 045 3 1 9.1 5.0 | 18.8 65.8 045 4 2 10.0 5.5
5750 14.9 58.8 045 2 1 14.0 7.7 | 19.7 67.5 050 4 2 17.7 9.7
5500 16.4 61.5 045 2 1 26.7 14.6 | 21.6 70.9 050 4 2 33.1 18.2
07/04/2024 at 1500 MDT | 07/04/2024 at 1800 MDT
|
CAPE... +0.3 LI... +0.6 | CAPE... +82.2 LI... -0.8
CINH... -0.6 K Index... +12.7 | CINH... -77.4 K Index... +20.8
|
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 -75.6 280 41 21 3.0 1.7 | -60.2 -76.4 285 42 22 4.4 2.4
45000 -54.9 -66.8 285 59 30 3.9 2.1 | -53.8 -64.8 285 58 30 3.9 2.2
40000 -48.9 -56.0 280 69 35 4.7 2.6 | -47.9 -54.2 285 71 36 4.3 2.4
38000 -46.1 -51.0 280 69 36 4.7 2.6 | -45.3 -49.5 285 72 37 4.3 2.4
36000 -43.3 -45.9 275 70 36 4.7 2.6 | -42.7 -44.9 285 72 37 4.3 2.4
34000 -39.5 -39.1 275 70 36 6.1 3.3 | -39.3 -38.7 285 72 37 5.1 2.8
32000 -35.8 -32.4 280 69 35 6.0 3.3 | -36.2 -33.2 280 71 37 5.1 2.8
30000 -31.5 -24.7 280 69 35 7.5 4.1 | -32.0 -25.6 280 72 37 7.6 4.2
29000 -29.2 -20.6 280 68 35 7.5 4.1 | -29.7 -21.5 280 72 37 7.6 4.2
28000 -27.0 -16.6 280 68 35 7.3 4.0 | -27.4 -17.3 280 72 37 6.9 3.8
27000 -24.9 -12.8 280 67 35 7.0 3.8 | -25.8 -14.4 280 69 35 5.2 2.8
26000 -22.8 -9.0 280 66 34 7.0 3.8 | -24.2 -11.6 285 65 33 5.2 2.8
25000 -20.7 -5.3 280 66 34 7.3 4.0 | -22.7 -8.9 285 61 31 5.1 2.8
24000 -19.2 -2.6 280 62 32 4.4 2.4 | -21.0 -5.8 285 57 29 5.6 3.0
23000 -17.8 -0.0 280 57 29 4.4 2.4 | -19.4 -2.9 280 52 27 5.6 3.1
22000 -16.5 2.3 280 51 27 4.3 2.4 | -17.7 0.1 280 47 24 5.5 3.0
21000 -14.6 5.7 280 49 25 6.9 3.8 | -15.5 4.1 280 45 23 7.9 4.4
20000 -12.6 9.3 280 47 24 6.9 3.8 | -13.2 8.2 275 43 22 8.0 4.4
19500 -11.5 11.3 280 46 24 6.9 3.8 | -12.0 10.4 275 43 22 8.0 4.4
19000 -10.5 13.1 280 45 23 7.4 4.1 | -10.8 12.6 275 42 22 8.1 4.5
18500 -9.4 15.1 275 45 23 7.6 4.2 | -9.6 14.7 270 41 21 8.2 4.5
18000 -8.3 17.1 275 44 22 7.7 4.2 | -8.5 16.7 270 39 20 8.3 4.5
17500 -7.1 19.2 275 43 22 8.3 4.6 | -6.7 19.9 270 37 19 8.5 4.6
17000 -5.3 22.5 270 41 21 8.3 4.6 | -5.5 22.1 270 35 18 8.6 4.7
16500 -4.1 24.6 270 40 20 8.2 4.5 | -4.2 24.4 275 33 17 8.8 4.8
16000 -2.9 26.8 270 38 19 8.2 4.5 | -2.9 26.8 275 31 16 8.7 4.8
15500 -1.7 28.9 270 36 18 7.8 4.3 | -1.6 29.1 275 29 15 8.8 4.8
15000 -0.6 30.9 270 33 17 7.8 4.3 | -0.3 31.5 275 26 14 8.9 4.9
14500 0.6 33.1 270 30 16 7.9 4.3 | 1.0 33.8 280 24 12 8.1 4.4
14000 1.7 35.1 275 27 14 7.9 4.4 | 2.1 35.8 280 20 10 7.9 4.3
13500 2.9 37.2 275 24 12 7.7 4.3 | 3.3 37.9 280 16 8 7.5 4.1
13000 4.0 39.2 275 21 11 7.5 4.1 | 4.4 39.9 275 12 6 7.2 3.9
12500 5.1 41.2 280 18 9 7.0 3.9 | 5.4 41.7 275 7 4 7.2 4.0
12000 6.0 42.8 285 13 7 6.3 3.4 | 6.5 43.7 275 5 3 7.3 4.0
11500 6.9 44.4 295 9 5 6.1 3.3 | 7.6 45.7 280 3 1 7.2 4.0
11000 7.7 45.9 315 6 3 5.7 3.1 | 8.6 47.5 310 2 1 7.0 3.8
10500 8.5 47.3 005 4 2 3.6 2.0 | 9.6 49.3 005 2 1 4.0 2.2
10250 8.7 47.7 015 4 2 5.0 2.8 | 9.8 49.6 015 2 1 5.6 3.1
10000 9.3 48.7 015 4 2 10.3 5.7 | 10.5 50.9 020 2 1 11.8 6.5
9750 10.1 50.2 020 4 2 10.6 5.8 | 11.3 52.3 025 2 1 11.6 6.3
9500 10.8 51.4 020 5 2 9.6 5.3 | 12.2 54.0 025 2 1 10.0 5.5
9250 11.5 52.7 020 5 2 8.3 4.6 | 12.8 55.0 025 3 1 7.8 4.3
9000 12.1 53.8 020 5 2 10.3 5.7 | 13.4 56.1 025 3 1 10.0 5.5
8750 13.0 55.4 020 5 3 12.0 6.6 | 14.3 57.7 025 3 1 11.5 6.3
8500 13.8 56.8 020 5 3 10.4 5.7 | 15.1 59.2 025 3 1 10.5 5.8
8250 14.6 58.3 020 5 3 9.3 5.1 | 15.8 60.4 025 3 1 10.1 5.6
8000 15.3 59.5 020 5 3 9.8 5.4 | 16.6 61.9 025 3 1 9.9 5.4
7750 16.0 60.8 020 5 3 10.1 5.6 | 17.3 63.1 025 3 2 9.4 5.1
7500 16.8 62.2 020 5 3 10.2 5.6 | 18.0 64.4 025 3 2 9.8 5.4
7250 17.5 63.5 020 5 3 10.1 5.5 | 18.8 65.8 025 3 2 10.2 5.6
7000 18.3 64.9 020 5 3 10.3 5.7 | 19.5 67.1 020 3 2 9.9 5.4
6750 19.1 66.4 020 5 3 10.7 5.9 | 20.3 68.5 020 3 2 9.9 5.4
6500 19.9 67.8 020 5 3 10.6 5.8 | 21.0 69.8 020 3 2 10.4 5.7
6250 20.7 69.3 020 5 3 10.3 5.6 | 21.8 71.2 020 3 2 10.5 5.7
6000 21.5 70.7 020 5 3 11.1 6.1 | 22.6 72.7 020 3 2 10.9 6.0
5750 22.5 72.5 020 5 3 19.0 10.4 | 23.5 74.3 015 3 2 15.2 8.4
5500 24.3 75.7 020 5 3 29.7 16.3 | 24.9 76.8 020 3 2 21.0 11.5
________________________________________________________________________________
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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