Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
598
UXUS97 KBOU 030113
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1813 MST Monday, November 2, 2026
This forecast is for Tuesday, November 3, 2026:
If the trigger temperature of 48.6 F/9.2 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 357 ft/min (1.8 m/s)
Maximum height of thermals.................. 11071 ft MSL (5775 ft AGL)
Forecast maximum temperature................... 57.0 F/14.3 C
Time of trigger temperature.................... 1045 MST
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................. 9891 ft MSL (4594 ft AGL)
Thermal soaring outlook for Wednesday 11/04.... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... 17828 ft MSL (12532 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Neither
Potential height of wave....................... 22743 ft MSL (17447 ft AGL)
Wave soaring outlook for Wednesday 11/04....... Poor
Remarks... Storm system moves into the midwest Tuesday, with n-nw flow aloft
weakening but skies clearing.
Sunrise/Sunset.................... 06:30:49 / 16:55:10 MST
Total possible sunshine........... 10 hr 24 min 21 sec (624 min 21 sec)
Altitude of sun at 11:42:59 MST... 34.85 degrees
Upper air data from numerical model forecast valid on 11/03/2026 at 0500 MST
Freezing level.................. 7431 ft MSL (2135 ft AGL)
Convective condensation level... 8707 ft MSL (3411 ft AGL)
Lifted condensation level....... 11137 ft MSL (5841 ft AGL)
Lifted index.................... +5.2
K index......................... +18.8
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 -60.9 -77.6 240 19 10 4.3 2.4 M M M M M
45000 -54.6 -66.3 255 18 9 2.9 1.6 M M M M M
40000 -50.1 -58.2 300 35 18 2.8 1.6 M M M M M
38000 -48.4 -55.1 310 40 21 2.8 1.6 M M M M M
36000 -46.7 -52.1 315 46 24 2.8 1.6 M M M M M
34000 -44.6 -48.3 320 52 27 5.1 2.8 M M M M M
32000 -41.5 -42.7 325 56 29 5.1 2.8 M M M M M
30000 -38.6 -37.5 325 53 27 4.2 2.3 39.2 102.6 19.0 M M
29000 -37.1 -34.8 325 39 20 4.2 2.3 36.4 97.5 17.1 M M
28000 -35.8 -32.4 325 28 14 4.2 2.3 34.3 93.7 15.7 M M
27000 -34.2 -29.6 325 20 10 8.8 4.8 32.7 90.9 14.7 M M
26000 -31.7 -25.1 330 21 11 8.4 4.6 32.1 89.8 14.4 M M
25000 -29.2 -20.6 335 22 11 8.4 4.6 31.6 88.9 14.2 M M
24000 -26.7 -16.1 340 23 12 7.9 4.3 31.2 88.1 13.9 M M
23000 -24.4 -11.9 350 23 12 7.8 4.3 30.3 86.6 13.4 M M
22000 -22.1 -7.8 360 23 12 7.9 4.3 29.7 85.4 13.0 M M
21000 -19.9 -3.8 005 24 12 5.8 3.2 28.9 84.0 12.4 M M
20000 -18.2 -0.8 015 24 12 6.0 3.3 27.5 81.5 11.4 M M
19500 -17.3 0.9 015 24 13 6.1 3.3 26.8 80.3 10.9 M M
19000 -16.4 2.5 020 25 13 6.3 3.4 26.2 79.2 10.4 M M
18500 -15.6 3.9 020 25 13 3.6 2.0 25.5 77.9 9.8 M M
18000 -15.2 4.6 020 24 12 3.3 1.8 24.3 75.8 8.8 M M
17500 -14.8 5.4 025 23 12 4.5 2.5 23.2 73.8 7.8 M M
17000 -13.8 7.2 025 23 12 7.7 4.2 22.7 72.9 7.4 M M
16500 -12.7 9.1 020 22 12 7.8 4.3 22.3 72.2 7.1 M M
16000 -11.7 10.9 020 22 12 5.8 3.2 21.8 71.3 6.6 M M
15500 -10.8 12.6 020 23 12 5.9 3.2 21.2 70.2 6.1 M M
15000 -9.5 14.9 015 24 12 5.8 3.2 20.2 68.4 5.2 M M
14500 -8.7 16.3 015 25 13 5.7 3.1 19.6 67.2 4.6 M M
14000 -7.8 18.0 015 26 13 6.4 3.5 19.0 66.1 4.1 M M
13500 -6.9 19.6 015 26 13 6.5 3.6 18.4 65.1 3.6 M M
13000 -6.0 21.2 015 27 14 5.2 2.8 17.8 64.0 3.0 M M
12500 -5.3 22.5 020 27 14 5.2 2.9 17.0 62.7 2.3 M M
12000 -4.6 23.7 020 28 14 4.3 2.3 16.3 61.3 1.5 M M
11500 -4.0 24.8 025 30 15 4.3 2.4 15.4 59.6 0.7 M M
11000 -3.5 25.7 025 32 17 2.0 1.1 14.3 57.8 -0.3 351 1.8
10500 -3.2 26.2 015 36 18 2.1 1.1 13.1 55.5 -1.5 328 1.7
10250 -3.1 26.4 015 38 19 0.6 0.3 12.4 54.4 -2.1 317 1.6
10000 -3.1 26.4 015 38 20 0.2 0.1 11.7 53.0 -2.8 310 1.6
9750 -3.0 26.6 010 39 20 1.9 1.1 11.0 51.8 -3.4 300 1.5
9500 -2.8 27.0 005 40 21 2.2 1.2 10.4 50.7 -4.0 288 1.5
9250 -2.7 27.1 005 41 21 1.9 1.1 9.8 49.6 -4.6 276 1.4
9000 -2.5 27.5 360 41 21 2.1 1.2 9.2 48.5 -5.2 264 1.3
8750 -2.3 27.9 360 41 21 4.5 2.5 8.7 47.6 -5.7 250 1.3
8500 -1.9 28.6 355 40 21 5.8 3.2 8.3 47.0 -6.1 230 1.2
8250 -1.5 29.3 350 38 20 5.3 2.9 8.0 46.4 -6.4 211 1.1
8000 -1.1 30.0 350 36 19 4.8 2.7 7.7 45.8 -6.8 192 1.0
7750 -0.7 30.7 350 34 18 6.8 3.7 7.3 45.2 -7.1 173 0.9
7500 -0.2 31.6 345 32 16 8.0 4.4 7.2 44.9 -7.3 149 0.8
7250 0.4 32.7 345 29 15 7.0 3.8 7.0 44.6 -7.5 125 0.6
7000 0.9 33.6 345 27 14 7.4 4.0 6.8 44.2 -7.7 102 0.5
6750 1.4 34.5 345 25 13 6.9 3.8 6.6 43.9 -8.0 78 0.4
6500 1.9 35.4 340 23 12 7.3 4.0 6.4 43.5 -8.2 56 0.3
6250 2.5 36.5 340 20 10 7.7 4.2 6.2 43.2 -8.4 32 0.2
6000 3.0 37.4 335 16 8 8.4 4.6 6.1 43.0 -8.6 8 0.0
5750 3.7 38.7 330 14 7 9.9 5.5 6.1 42.9 -8.7 M M
5500 4.4 39.9 330 11 6 9.8 5.4 6.1 42.9 -8.7 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/03/2026 at 0800 MST | 11/03/2026 at 1100 MST
|
CAPE... 0.0 LI... +4.9 | CAPE... 0.0 LI... +4.3
CINH... 0.0 K Index... +17.7 | CINH... 0.0 K Index... +13.1
|
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 -60.6 -77.1 250 21 11 3.6 2.0 | -60.3 -76.5 250 21 11 2.3 1.3
45000 -55.3 -67.5 255 17 9 2.9 1.6 | -56.9 -70.4 260 24 13 2.2 1.2
40000 -50.7 -59.3 295 40 21 3.0 1.7 | -53.5 -64.3 290 57 29 2.2 1.2
38000 -49.8 -57.6 305 52 27 1.2 0.7 | -52.0 -61.6 295 62 32 2.6 1.4
36000 -49.1 -56.4 315 66 34 1.2 0.7 | -50.4 -58.7 305 66 34 2.6 1.4
34000 -46.7 -52.1 320 76 39 8.1 4.4 | -47.1 -52.8 310 70 36 8.0 4.4
32000 -41.9 -43.4 320 78 40 8.1 4.4 | -42.3 -44.1 310 71 37 8.0 4.4
30000 -37.4 -35.3 320 74 38 6.4 3.5 | -37.4 -35.3 310 70 36 8.6 4.7
29000 -35.5 -31.9 320 65 33 6.4 3.5 | -34.8 -30.6 310 67 35 8.6 4.7
28000 -33.1 -27.6 320 54 28 6.3 3.5 | -32.2 -26.0 310 65 33 8.6 4.7
27000 -31.4 -24.5 320 45 23 4.4 2.4 | -30.0 -22.0 310 60 31 3.0 1.6
26000 -30.1 -22.2 320 35 18 4.5 2.5 | -29.0 -20.2 305 50 26 3.5 1.9
25000 -28.8 -19.8 320 26 14 4.5 2.5 | -28.0 -18.4 300 40 20 3.5 1.9
24000 -27.2 -17.0 325 19 10 7.9 4.3 | -26.8 -16.2 295 31 16 6.3 3.5
23000 -24.9 -12.8 330 17 9 7.9 4.3 | -24.7 -12.5 290 26 13 7.0 3.8
22000 -22.6 -8.7 345 15 8 8.0 4.4 | -22.6 -8.7 285 21 11 7.1 3.9
21000 -20.3 -4.5 355 15 8 7.2 4.0 | -20.5 -4.9 275 17 9 7.6 4.2
20000 -18.1 -0.6 355 15 8 7.3 4.0 | -18.2 -0.8 285 17 9 7.6 4.2
19500 -17.0 1.4 360 15 8 7.3 4.0 | -17.1 1.2 285 16 8 7.6 4.2
19000 -16.0 3.2 360 15 8 7.6 4.2 | -16.0 3.2 290 16 8 7.7 4.3
18500 -15.0 5.0 360 15 8 5.0 2.7 | -14.9 5.2 295 16 8 6.3 3.5
18000 -14.3 6.3 005 15 8 5.0 2.8 | -14.0 6.8 295 15 8 6.2 3.4
17500 -13.5 7.7 005 16 8 5.4 3.0 | -12.6 9.3 305 14 7 6.7 3.7
17000 -12.7 9.1 005 16 8 5.9 3.3 | -11.7 10.9 305 15 8 6.7 3.7
16500 -11.8 10.8 005 16 8 6.2 3.4 | -10.7 12.7 310 15 8 6.6 3.6
16000 -11.2 11.8 005 16 8 2.2 1.2 | -9.7 14.5 315 15 8 6.5 3.6
15500 -10.9 12.4 360 16 8 2.5 1.4 | -8.8 16.2 320 15 8 6.5 3.6
15000 -10.4 13.3 355 17 9 5.1 2.8 | -7.8 18.0 320 16 8 6.9 3.8
14500 -9.2 15.4 350 18 9 5.5 3.0 | -6.8 19.8 320 17 9 7.0 3.9
14000 -8.3 17.1 345 20 10 7.2 4.0 | -5.9 21.4 320 17 9 5.0 2.7
13500 -7.2 19.0 345 21 11 7.3 4.0 | -5.1 22.8 320 18 9 5.2 2.8
13000 -6.4 20.5 345 22 11 5.0 2.7 | -4.4 24.1 320 18 9 5.0 2.7
12500 -5.6 21.9 350 22 11 5.3 2.9 | -3.7 25.3 320 18 9 5.1 2.8
12000 -5.0 23.0 350 23 12 3.6 2.0 | -3.1 26.4 320 17 9 3.2 1.8
11500 -4.5 23.9 355 23 12 3.5 1.9 | -2.6 27.3 320 18 9 3.0 1.7
11000 -3.9 25.0 355 24 12 4.6 2.5 | -2.2 28.0 325 18 9 2.6 1.4
10500 -3.2 26.2 355 25 13 5.2 2.8 | -1.9 28.6 325 18 9 2.6 1.4
10250 -2.9 26.8 355 25 13 1.9 1.1 | -1.7 28.9 330 18 9 2.1 1.1
10000 -2.9 26.8 355 25 13 1.5 0.8 | -1.5 29.3 330 18 9 2.8 1.5
9750 -2.6 27.3 360 25 13 5.3 2.9 | -1.2 29.8 335 18 9 4.1 2.2
9500 -2.2 28.0 360 26 13 5.1 2.8 | -0.9 30.4 335 18 9 4.0 2.2
9250 -1.8 28.8 360 26 13 3.8 2.1 | -0.6 30.9 340 19 10 3.9 2.1
9000 -1.6 29.1 360 26 14 3.2 1.8 | -0.4 31.3 345 19 10 3.9 2.1
8750 -1.3 29.7 360 27 14 4.5 2.5 | -0.0 32.0 345 19 10 4.2 2.3
8500 -0.9 30.4 360 28 14 5.6 3.1 | 0.3 32.5 350 18 9 4.8 2.6
8250 -0.5 31.1 360 28 14 6.5 3.6 | 0.7 33.3 350 17 9 6.2 3.4
8000 0.0 32.0 355 27 14 6.5 3.6 | 1.2 34.2 350 14 7 6.9 3.8
7750 0.6 33.1 355 27 14 8.3 4.6 | 1.7 35.1 350 12 6 8.4 4.6
7500 1.3 34.3 350 26 13 9.0 4.9 | 2.4 36.3 350 11 6 10.0 5.5
7250 1.9 35.4 350 23 12 7.8 4.3 | 3.2 37.8 350 11 5 9.8 5.4
7000 2.5 36.5 345 21 11 8.3 4.6 | 3.9 39.0 350 10 5 10.0 5.5
6750 3.0 37.4 345 19 10 7.4 4.0 | 4.6 40.3 350 10 5 9.7 5.3
6500 3.5 38.3 340 16 8 6.3 3.5 | 5.4 41.7 350 10 5 10.2 5.6
6250 4.0 39.2 335 12 6 6.3 3.5 | 6.2 43.2 350 10 5 11.1 6.1
6000 4.4 39.9 320 9 5 6.6 3.6 | 7.0 44.6 350 9 5 10.1 5.5
5750 5.0 41.0 310 7 4 9.9 5.4 | 7.8 46.0 350 9 5 14.6 8.0
5500 5.9 42.6 305 6 3 14.3 7.8 | 9.3 48.7 350 8 4 24.3 13.4
11/03/2026 at 1400 MST | 11/03/2026 at 1700 MST
|
CAPE... 0.0 LI... +3.2 | CAPE... 0.0 LI... +3.4
CINH... 0.0 K Index... +10.5 | CINH... 0.0 K Index... -5.8
|
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 -60.7 -77.3 265 22 11 1.8 1.0 | -60.5 -76.9 270 24 12 1.1 0.6
45000 -58.0 -72.4 280 31 16 2.0 1.1 | -58.6 -73.5 285 35 18 2.1 1.1
40000 -55.0 -67.0 300 61 31 2.1 1.2 | -55.5 -67.9 300 59 30 2.1 1.1
38000 -52.5 -62.5 300 65 33 4.8 2.6 | -52.9 -63.2 300 63 32 5.0 2.7
36000 -49.6 -57.3 300 65 33 4.8 2.6 | -49.9 -57.8 295 64 33 5.0 2.7
34000 -46.4 -51.5 300 64 33 6.2 3.4 | -46.5 -51.7 295 64 33 6.6 3.6
32000 -42.2 -44.0 300 62 32 6.2 3.4 | -42.6 -44.7 300 59 30 6.5 3.6
30000 -37.8 -36.0 305 61 31 9.0 5.0 | -37.7 -35.9 300 56 29 8.5 4.7
29000 -35.1 -31.2 305 61 31 9.0 5.0 | -35.1 -31.2 300 55 28 8.5 4.7
28000 -32.3 -26.1 305 60 31 9.0 5.0 | -32.6 -26.7 300 54 28 8.5 4.7
27000 -29.9 -21.8 300 60 31 5.9 3.3 | -30.1 -22.2 305 54 28 7.4 4.1
26000 -28.0 -18.4 300 58 30 6.2 3.4 | -27.9 -18.2 305 55 28 7.5 4.1
25000 -26.2 -15.2 300 56 29 6.2 3.4 | -25.6 -14.1 305 56 29 7.5 4.1
24000 -24.4 -11.9 300 53 27 3.8 2.1 | -23.5 -10.3 305 56 29 4.4 2.4
23000 -23.5 -10.3 300 44 23 3.1 1.7 | -22.4 -8.3 305 49 25 3.8 2.1
22000 -22.5 -8.5 295 35 18 3.1 1.7 | -21.3 -6.3 310 42 22 3.8 2.1
21000 -21.3 -6.3 290 28 14 6.9 3.8 | -20.0 -4.0 310 36 19 5.4 3.0
20000 -19.4 -2.9 290 25 13 6.7 3.7 | -18.4 -1.1 310 30 16 5.3 2.9
19500 -18.4 -1.1 285 24 12 6.7 3.7 | -17.6 0.3 310 27 14 5.3 2.9
19000 -17.4 0.7 285 23 12 6.8 3.7 | -16.8 1.8 310 24 13 5.2 2.9
18500 -16.4 2.5 285 22 11 7.1 3.9 | -16.0 3.2 305 22 11 5.7 3.1
18000 -15.3 4.5 285 22 11 7.2 4.0 | -15.2 4.6 305 22 11 5.8 3.2
17500 -14.3 6.3 290 22 11 7.1 3.9 | -14.3 6.3 305 21 11 5.9 3.2
17000 -13.3 8.1 295 22 11 6.7 3.7 | -13.4 7.9 305 22 11 6.0 3.3
16500 -11.8 10.8 300 22 11 7.0 3.9 | -12.5 9.5 305 23 12 5.9 3.2
16000 -10.7 12.7 300 23 12 7.4 4.1 | -11.6 11.1 305 23 12 7.0 3.8
15500 -9.6 14.7 300 23 12 7.4 4.1 | -10.0 14.0 300 25 13 7.1 3.9
15000 -8.5 16.7 305 23 12 7.4 4.0 | -8.9 16.0 295 25 13 8.0 4.4
14500 -7.5 18.5 305 23 12 7.5 4.1 | -7.7 18.1 295 26 13 8.1 4.4
14000 -6.4 20.5 305 23 12 6.7 3.7 | -6.6 20.1 295 26 13 7.8 4.3
13500 -5.4 22.3 305 22 12 6.9 3.8 | -5.5 22.1 290 26 13 8.2 4.5
13000 -4.5 23.9 305 22 11 5.4 3.0 | -4.5 23.9 290 25 13 5.5 3.0
12500 -3.8 25.2 305 21 11 5.4 3.0 | -3.8 25.2 295 23 12 5.6 3.1
12000 -3.1 26.4 310 20 11 4.5 2.4 | -3.2 26.2 295 21 11 2.8 1.5
11500 -2.4 27.7 315 19 10 4.4 2.4 | -2.9 26.8 300 18 9 2.5 1.4
11000 -1.9 28.6 320 18 9 2.9 1.6 | -2.6 27.3 310 15 8 1.3 0.7
10500 -1.5 29.3 330 17 9 3.2 1.7 | -2.5 27.5 315 13 7 1.4 0.7
10250 -1.3 29.7 335 17 9 1.0 0.6 | -2.4 27.7 320 12 6 0.4 0.2
10000 -1.3 29.7 335 17 9 1.3 0.7 | -2.3 27.9 325 11 6 3.7 2.0
9750 -1.1 30.0 345 15 8 3.8 2.1 | -1.8 28.8 330 10 5 7.3 4.0
9500 -0.8 30.6 355 14 7 2.8 1.6 | -1.3 29.7 335 9 4 6.3 3.5
9250 -0.6 30.9 005 13 7 4.6 2.5 | -0.9 30.4 340 7 4 6.9 3.8
9000 -0.1 31.8 010 12 6 7.5 4.1 | -0.3 31.5 350 7 4 8.3 4.6
8750 0.5 32.9 010 12 6 9.5 5.2 | 0.4 32.7 355 7 4 10.4 5.7
8500 1.3 34.3 015 11 6 10.4 5.7 | 1.2 34.2 360 7 3 10.9 6.0
8250 2.0 35.6 015 11 6 9.8 5.4 | 2.0 35.6 005 7 3 9.9 5.4
8000 2.7 36.9 015 11 6 9.7 5.3 | 2.7 36.9 010 7 3 9.5 5.2
7750 3.5 38.3 020 11 6 10.1 5.6 | 3.4 38.1 015 7 4 9.8 5.4
7500 4.2 39.6 020 11 6 10.3 5.7 | 4.2 39.6 020 7 4 9.7 5.3
7250 5.0 41.0 020 11 6 10.1 5.5 | 4.9 40.8 020 7 4 9.5 5.2
7000 5.8 42.4 020 11 6 10.2 5.6 | 5.6 42.1 025 7 4 9.3 5.1
6750 6.5 43.7 020 11 6 9.7 5.3 | 6.3 43.3 025 7 4 10.2 5.6
6500 7.3 45.1 020 11 5 10.2 5.6 | 7.1 44.8 030 7 4 10.3 5.6
6250 8.1 46.6 020 10 5 11.1 6.1 | 7.8 46.0 030 7 4 9.3 5.1
6000 8.9 48.0 020 10 5 10.2 5.6 | 8.5 47.3 035 7 4 10.2 5.6
5750 9.7 49.5 020 10 5 13.0 7.2 | 9.3 48.7 035 7 4 7.9 4.3
5500 10.9 51.6 020 9 5 20.4 11.2 | 9.6 49.3 035 6 3 2.7 1.5
________________________________________________________________________________
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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