Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
299
UXUS97 KBOU 260019
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1819 MDT Saturday, May 25, 2024
This forecast is for Sunday, May 26, 2024:
If the trigger temperature of 61.1 F/16.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1157 ft/min (5.9 m/s)
Maximum height of thermals.................. 18317 ft MSL (13005 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 0930 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................. 14955 ft MSL (9643 ft AGL)
Thermal soaring outlook for Monday 05/27....... Excellent
Wave Soaring Index............................. Good
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....................... 19071 ft MSL (13759 ft AGL)
Wave soaring outlook for Monday 05/27.......... Poor
Remarks...
Sunrise/Sunset.................... 05:35:55 / 20:17:20 MDT
Total possible sunshine........... 14 hr 41 min 25 sec (881 min 25 sec)
Altitude of sun at 12:56:38 MDT... 71.53 degrees
Upper air data from numerical model forecast valid on 05/26/2024 at 0600 MDT
Freezing level.................. 10725 ft MSL (5413 ft AGL)
Convective condensation level... 13617 ft MSL (8305 ft AGL)
Lifted condensation level....... 15680 ft MSL (10368 ft AGL)
Lifted index.................... -3.2
K index......................... +20.1
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 -54.4 -65.9 245 49 25 1.4 0.8 M M M M M
45000 -52.4 -62.3 260 55 28 0.7 0.4 M M M M M
40000 -51.1 -60.0 280 50 26 0.8 0.4 M M M M M
38000 -50.2 -58.4 280 49 25 1.9 1.1 M M M M M
36000 -49.1 -56.4 280 47 24 1.9 1.1 M M M M M
34000 -47.5 -53.5 280 47 24 5.7 3.1 M M M M M
32000 -44.1 -47.4 290 47 24 5.6 3.1 M M M M M
30000 -40.4 -40.7 295 46 23 5.1 2.8 35.8 96.4 9.4 M M
29000 -38.9 -38.0 295 41 21 5.1 2.8 33.9 93.0 8.0 M M
28000 -37.3 -35.1 295 37 19 5.1 2.8 32.1 89.8 6.8 M M
27000 -35.8 -32.4 290 33 17 6.5 3.6 30.5 86.9 5.6 M M
26000 -33.7 -28.7 295 29 15 7.1 3.9 29.4 84.9 4.8 M M
25000 -31.5 -24.7 295 25 13 7.1 3.9 28.4 83.1 4.0 M M
24000 -29.4 -20.9 300 21 11 7.5 4.1 27.5 81.6 3.3 M M
23000 -27.1 -16.8 300 22 11 8.0 4.4 26.8 80.2 2.7 M M
22000 -24.7 -12.5 305 23 12 8.0 4.4 26.2 79.1 2.2 M M
21000 -22.3 -8.1 310 24 12 7.8 4.3 25.6 78.1 1.8 M M
20000 -20.0 -4.0 310 25 13 7.7 4.2 24.8 76.7 1.1 M M
19500 -18.9 -2.0 310 26 13 7.7 4.2 24.5 76.0 0.8 M M
19000 -17.7 0.1 310 26 14 7.7 4.2 24.1 75.5 0.5 M M
18500 -16.6 2.1 310 27 14 7.4 4.1 23.9 74.9 0.2 M M
18000 -15.5 4.1 310 27 14 7.1 3.9 23.4 74.1 -0.2 1136 5.8
17500 -14.5 5.9 315 27 14 7.1 3.9 22.9 73.3 -0.6 1090 5.5
17000 -13.4 7.9 315 27 14 7.3 4.0 22.5 72.5 -1.0 1043 5.3
16500 -12.4 9.7 315 27 14 7.3 4.0 22.1 71.7 -1.4 997 5.1
16000 -10.8 12.6 315 27 14 6.7 3.7 21.4 70.5 -2.1 928 4.7
15500 -9.8 14.4 315 27 14 6.8 3.7 20.9 69.6 -2.6 884 4.5
15000 -8.9 16.0 315 27 14 6.3 3.5 20.4 68.6 -3.1 840 4.3
14500 -8.0 17.6 315 27 14 6.3 3.5 19.8 67.6 -3.6 798 4.1
14000 -7.0 19.4 315 26 13 6.1 3.3 19.2 66.6 -4.2 756 3.8
13500 -6.2 20.8 320 24 13 6.0 3.3 18.6 65.5 -4.8 715 3.6
13000 -5.3 22.5 320 23 12 6.8 3.8 18.0 64.4 -5.4 675 3.4
12500 -4.2 24.4 325 22 11 7.5 4.1 17.6 63.7 -5.8 627 3.2
12000 -3.1 26.4 325 21 11 7.9 4.4 17.3 63.1 -6.2 579 2.9
11500 -1.9 28.6 330 19 10 8.4 4.6 17.0 62.7 -6.5 527 2.7
11000 -0.6 30.9 335 18 9 8.5 4.7 16.8 62.3 -6.7 475 2.4
10500 0.7 33.3 335 18 9 8.2 4.5 16.7 62.0 -6.9 421 2.1
10250 1.3 34.3 335 18 9 10.7 5.9 16.6 61.9 -7.0 393 2.0
10000 2.3 36.1 330 18 9 11.3 6.2 16.8 62.2 -6.8 359 1.8
9750 3.0 37.4 330 18 10 9.3 5.1 16.8 62.2 -6.8 330 1.7
9500 3.7 38.7 325 20 10 9.8 5.4 16.8 62.2 -6.9 300 1.5
9250 4.4 39.9 325 21 11 10.0 5.5 16.8 62.2 -6.9 271 1.4
9000 5.1 41.2 320 22 11 7.5 4.1 16.8 62.2 -6.9 243 1.2
8750 5.5 41.9 315 25 13 5.0 2.7 16.4 61.6 -7.3 223 1.1
8500 5.9 42.6 310 27 14 5.5 3.0 16.1 61.0 -7.6 204 1.0
8250 6.3 43.3 305 30 16 4.8 2.6 15.7 60.3 -8.0 185 0.9
8000 6.6 43.9 300 32 17 3.5 1.9 15.3 59.6 -8.5 170 0.9
7750 6.8 44.2 300 32 17 4.1 2.3 14.8 58.7 -9.0 155 0.8
7500 7.1 44.8 295 31 16 3.9 2.1 14.4 58.0 -9.4 139 0.7
7250 7.4 45.3 295 30 16 6.5 3.6 14.0 57.2 -9.9 122 0.6
7000 8.1 46.6 295 28 15 9.6 5.3 13.9 57.1 -10.0 96 0.5
6750 8.7 47.7 295 26 13 7.9 4.3 13.9 57.0 -10.1 69 0.3
6500 9.3 48.7 295 24 12 7.3 4.0 13.7 56.6 -10.3 45 0.2
6250 9.8 49.6 295 22 11 8.0 4.4 13.5 56.4 -10.5 20 0.1
6000 10.4 50.7 295 19 10 7.9 4.4 13.4 56.1 -10.6 M M
5750 11.0 51.8 290 16 8 8.5 4.7 13.3 55.9 -10.8 M M
5500 11.6 52.9 290 13 7 5.2 2.8 13.1 55.6 -11.0 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/26/2024 at 0900 MDT | 05/26/2024 at 1200 MDT
|
CAPE... 0.0 LI... +3.6 | CAPE... 0.0 LI... +3.7
CINH... 0.0 K Index... +8.7 | CINH... 0.0 K Index... -6.3
|
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 -54.6 -66.3 255 50 26 0.6 0.3 | -55.1 -67.2 260 47 24 1.4 0.8
45000 -53.5 -64.3 265 57 30 2.2 1.2 | -53.2 -63.8 270 53 27 0.3 0.2
40000 -50.2 -58.4 270 60 31 2.1 1.1 | -52.7 -62.9 280 62 32 0.3 0.2
38000 -49.8 -57.6 275 57 29 0.2 0.1 | -51.5 -60.7 285 61 31 2.9 1.6
36000 -49.6 -57.3 275 53 27 0.2 0.1 | -49.7 -57.5 295 59 30 2.9 1.6
34000 -48.9 -56.0 280 49 25 4.3 2.4 | -47.7 -53.9 300 57 29 4.4 2.4
32000 -46.2 -51.2 285 44 22 4.5 2.4 | -45.1 -49.2 300 54 28 4.4 2.4
30000 -43.0 -45.4 290 40 21 8.1 4.4 | -41.6 -42.9 295 51 26 6.8 3.8
29000 -40.6 -41.1 295 40 20 8.2 4.5 | -39.5 -39.1 295 49 25 6.8 3.7
28000 -37.5 -35.5 300 39 20 8.2 4.5 | -37.5 -35.5 295 47 24 6.8 3.7
27000 -35.1 -31.2 300 38 20 7.7 4.2 | -35.3 -31.5 290 45 23 8.8 4.8
26000 -32.7 -26.9 295 35 18 7.7 4.2 | -32.7 -26.9 290 43 22 8.6 4.7
25000 -30.4 -22.7 290 32 17 7.7 4.2 | -30.2 -22.4 290 40 21 8.6 4.7
24000 -28.1 -18.6 285 30 15 7.8 4.3 | -27.6 -17.7 290 38 20 8.3 4.5
23000 -25.8 -14.4 285 30 15 7.8 4.3 | -25.2 -13.4 290 37 19 8.2 4.5
22000 -23.5 -10.3 285 29 15 7.8 4.3 | -22.7 -8.9 290 35 18 8.2 4.5
21000 -21.1 -6.0 290 29 15 7.8 4.3 | -20.3 -4.5 290 33 17 7.6 4.2
20000 -18.8 -1.8 295 27 14 7.9 4.3 | -18.0 -0.4 290 30 16 7.7 4.2
19500 -17.6 0.3 295 27 14 7.9 4.3 | -16.9 1.6 290 29 15 7.7 4.2
19000 -16.4 2.5 300 26 13 7.9 4.3 | -15.7 3.7 290 28 14 7.7 4.2
18500 -15.3 4.5 305 25 13 7.3 4.0 | -14.6 5.7 290 27 14 7.2 3.9
18000 -14.2 6.4 305 25 13 7.2 3.9 | -13.5 7.7 290 25 13 7.1 3.9
17500 -13.2 8.2 310 24 12 7.1 3.9 | -12.5 9.5 290 23 12 7.0 3.8
17000 -12.2 10.0 310 23 12 6.8 3.7 | -11.5 11.3 290 21 11 6.5 3.5
16500 -11.2 11.8 315 21 11 6.8 3.7 | -10.5 13.1 295 19 10 6.5 3.6
16000 -10.2 13.6 320 21 11 7.2 4.0 | -9.5 14.9 295 18 9 6.3 3.4
15500 -9.1 15.6 320 20 10 7.3 4.0 | -8.2 17.2 290 15 8 6.3 3.4
15000 -8.0 17.6 320 20 10 6.8 3.7 | -7.2 19.0 290 14 7 6.0 3.3
14500 -7.1 19.2 325 18 9 6.5 3.5 | -6.4 20.5 290 12 6 6.1 3.3
14000 -5.7 21.7 325 17 9 6.9 3.8 | -5.5 22.1 290 11 6 5.6 3.1
13500 -4.6 23.7 330 15 8 6.9 3.8 | -4.7 23.5 290 10 5 5.5 3.0
13000 -3.6 25.5 330 14 7 6.9 3.8 | -3.8 25.2 290 9 5 7.2 3.9
12500 -2.6 27.3 330 13 7 6.9 3.8 | -2.7 27.1 300 8 4 7.5 4.1
12000 -1.6 29.1 330 12 6 7.0 3.8 | -1.5 29.3 310 8 4 9.0 4.9
11500 -0.5 31.1 325 10 5 7.1 3.9 | -0.0 32.0 320 11 6 9.5 5.2
11000 0.5 32.9 320 9 5 7.3 4.0 | 1.4 34.5 325 14 7 8.4 4.6
10500 1.6 34.9 320 10 5 6.8 3.7 | 2.5 36.5 315 18 9 7.5 4.1
10250 2.2 36.0 320 10 5 10.5 5.8 | 3.1 37.6 315 20 10 9.8 5.4
10000 3.1 37.6 320 10 5 11.5 6.3 | 3.8 38.8 310 22 11 7.7 4.2
9750 3.8 38.8 320 12 6 8.4 4.6 | 4.1 39.4 310 21 11 3.9 2.1
9500 4.5 40.1 315 13 7 9.4 5.2 | 4.4 39.9 305 21 11 5.0 2.7
9250 5.2 41.4 315 15 8 8.5 4.7 | 4.7 40.5 305 20 10 5.4 3.0
9000 5.8 42.4 315 17 9 7.0 3.8 | 5.2 41.4 305 20 10 8.5 4.7
8750 6.3 43.3 310 20 10 6.1 3.3 | 5.9 42.6 305 19 10 10.3 5.6
8500 6.8 44.2 305 24 12 7.5 4.1 | 6.6 43.9 305 18 10 9.7 5.3
8250 7.3 45.1 305 27 14 3.0 1.6 | 7.3 45.1 305 18 9 10.6 5.8
8000 7.2 45.0 300 27 14 -2.3 -1.3 | 8.1 46.6 305 18 9 10.7 5.9
7750 7.0 44.6 295 26 13 0.5 0.3 | 8.9 48.0 305 18 9 9.5 5.2
7500 7.1 44.8 295 24 12 1.6 0.9 | 9.6 49.3 305 17 9 9.2 5.0
7250 7.2 45.0 290 22 11 6.7 3.6 | 10.3 50.5 305 17 9 10.0 5.5
7000 8.0 46.4 290 22 11 11.1 6.1 | 11.1 52.0 305 17 9 10.5 5.8
6750 8.7 47.7 290 21 11 9.4 5.2 | 11.8 53.2 305 17 9 9.5 5.2
6500 9.4 48.9 290 21 11 10.0 5.5 | 12.5 54.5 305 17 9 10.3 5.6
6250 10.2 50.4 290 20 10 10.9 6.0 | 13.4 56.1 305 16 8 12.2 6.7
6000 11.0 51.8 290 19 10 10.9 6.0 | 14.3 57.7 305 16 8 12.0 6.6
5750 11.9 53.4 290 18 9 11.5 6.3 | 15.2 59.4 305 16 8 12.5 6.8
5500 12.9 55.2 290 17 9 16.9 9.2 | 16.3 61.3 305 15 8 20.6 11.3
05/26/2024 at 1500 MDT | 05/26/2024 at 1800 MDT
|
CAPE... +1.4 LI... +1.2 | CAPE... 0.0 LI... +2.0
CINH... -0.4 K Index... +19.1 | CINH... 0.0 K Index... +7.6
|
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 -56.0 -68.8 265 45 23 1.4 0.8 | -56.7 -70.1 270 46 24 0.9 0.5
45000 -54.2 -65.6 275 51 26 -0.7 -0.4 | -55.7 -68.3 280 52 27 -1.0 -0.5
40000 -55.3 -67.5 290 56 29 -0.6 -0.3 | -57.2 -71.0 285 55 28 -1.1 -0.6
38000 -53.6 -64.5 295 57 29 4.1 2.3 | -54.9 -66.8 290 56 29 5.2 2.9
36000 -51.1 -60.0 305 59 30 4.1 2.3 | -51.8 -61.2 290 57 30 5.2 2.9
34000 -48.1 -54.6 310 61 31 6.8 3.8 | -48.0 -54.4 295 58 30 7.7 4.2
32000 -44.0 -47.2 310 61 32 6.8 3.8 | -42.9 -45.2 300 56 29 7.6 4.2
30000 -39.0 -38.2 315 61 31 8.0 4.4 | -38.4 -37.1 300 54 28 7.4 4.0
29000 -36.6 -33.9 315 59 30 8.0 4.4 | -36.2 -33.2 300 53 27 7.4 4.0
28000 -34.3 -29.7 315 57 29 8.0 4.4 | -34.0 -29.2 300 52 27 7.4 4.1
27000 -32.1 -25.8 310 55 28 6.1 3.3 | -31.6 -24.9 300 50 26 8.6 4.7
26000 -30.2 -22.4 310 52 27 6.2 3.4 | -29.0 -20.2 300 47 24 8.6 4.7
25000 -28.3 -18.9 305 48 25 6.2 3.4 | -26.5 -15.7 305 44 22 8.6 4.7
24000 -26.5 -15.7 300 46 24 6.9 3.8 | -24.1 -11.4 310 41 21 6.0 3.3
23000 -24.4 -11.9 300 44 23 7.0 3.8 | -22.2 -8.0 305 41 21 6.2 3.4
22000 -22.3 -8.1 300 42 21 7.0 3.8 | -20.3 -4.5 305 41 21 6.3 3.4
21000 -20.2 -4.4 295 39 20 7.9 4.4 | -18.4 -1.1 300 40 21 7.3 4.0
20000 -17.8 -0.0 295 36 19 7.9 4.3 | -16.2 2.8 300 38 19 7.2 4.0
19500 -16.6 2.1 290 35 18 7.9 4.3 | -15.1 4.8 295 36 19 7.2 4.0
19000 -15.4 4.3 290 33 17 8.0 4.4 | -14.0 6.8 295 35 18 7.4 4.0
18500 -14.4 6.1 290 32 16 6.3 3.4 | -13.0 8.6 295 33 17 6.0 3.3
18000 -13.5 7.7 290 30 16 6.2 3.4 | -12.1 10.2 295 32 16 6.1 3.3
17500 -12.6 9.3 290 29 15 5.9 3.3 | -11.2 11.8 290 31 16 5.9 3.2
17000 -11.8 10.8 290 27 14 5.3 2.9 | -10.0 14.0 295 28 14 5.7 3.1
16500 -11.0 12.2 290 25 13 5.1 2.8 | -9.1 15.6 295 26 13 6.7 3.7
16000 -9.5 14.9 295 23 12 7.6 4.2 | -8.1 17.4 295 26 13 7.2 3.9
15500 -8.4 16.9 295 24 12 7.5 4.1 | -7.0 19.4 300 26 13 7.3 4.0
15000 -7.4 18.7 300 24 12 6.3 3.5 | -5.9 21.4 295 27 14 7.6 4.2
14500 -6.5 20.3 300 24 12 6.4 3.5 | -4.8 23.4 295 28 14 7.7 4.2
14000 -5.6 21.9 300 23 12 6.6 3.6 | -3.8 25.2 295 28 14 6.5 3.6
13500 -4.6 23.7 300 22 11 6.5 3.6 | -2.9 26.8 290 26 14 6.5 3.6
13000 -3.6 25.5 300 20 10 8.1 4.5 | -1.8 28.8 290 25 13 8.5 4.7
12500 -2.4 27.7 300 17 9 8.1 4.4 | -0.6 30.9 290 22 11 8.4 4.6
12000 -1.1 30.0 300 15 8 9.8 5.4 | 0.6 33.1 295 20 10 8.9 4.9
11500 0.3 32.5 305 14 7 10.1 5.5 | 1.9 35.4 295 18 9 8.9 4.9
11000 1.8 35.2 305 14 7 8.6 4.7 | 3.3 37.9 295 16 8 9.6 5.3
10500 3.0 37.4 305 14 7 7.5 4.1 | 4.7 40.5 300 15 8 10.3 5.7
10250 3.7 38.7 305 14 7 12.3 6.7 | 5.4 41.7 300 14 7 7.1 3.9
10000 4.8 40.6 305 14 7 13.1 7.2 | 5.9 42.6 300 14 7 7.9 4.4
9750 5.5 41.9 305 13 7 8.9 4.9 | 6.7 44.1 300 14 7 11.7 6.4
9500 6.2 43.2 305 13 7 10.2 5.6 | 7.5 45.5 300 14 7 11.0 6.0
9250 7.0 44.6 305 13 7 9.2 5.1 | 8.3 46.9 300 14 7 10.1 5.6
9000 7.7 45.9 305 13 7 9.4 5.1 | 9.0 48.2 300 13 7 9.5 5.2
8750 8.4 47.1 305 13 7 10.1 5.5 | 9.8 49.6 300 13 7 10.3 5.7
8500 9.1 48.4 305 13 7 9.8 5.4 | 10.5 50.9 300 13 7 10.1 5.5
8250 9.9 49.8 305 13 7 10.3 5.6 | 11.3 52.3 305 13 7 10.2 5.6
8000 10.7 51.3 305 13 7 10.4 5.7 | 12.1 53.8 305 13 7 10.1 5.5
7750 11.4 52.5 305 13 6 9.7 5.3 | 12.8 55.0 305 13 6 9.7 5.3
7500 12.1 53.8 305 13 6 9.9 5.4 | 13.5 56.3 305 12 6 9.8 5.4
7250 12.9 55.2 305 12 6 10.9 6.0 | 14.3 57.7 305 12 6 10.3 5.7
7000 13.7 56.7 305 12 6 11.2 6.2 | 15.1 59.2 305 12 6 10.5 5.7
6750 14.5 58.1 305 12 6 8.8 4.8 | 15.8 60.4 305 12 6 9.0 5.0
6500 15.1 59.2 305 12 6 9.4 5.1 | 16.5 61.7 305 12 6 9.6 5.3
6250 16.0 60.8 305 12 6 12.1 6.6 | 17.3 63.1 305 11 6 11.3 6.2
6000 16.8 62.2 305 11 6 11.2 6.2 | 18.1 64.6 305 11 6 10.7 5.9
5750 17.7 63.9 305 11 6 12.7 7.0 | 18.9 66.0 305 11 6 11.2 6.1
5500 18.9 66.0 310 11 6 22.1 12.1 | 19.8 67.6 310 10 5 15.4 8.4
________________________________________________________________________________
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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