Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
333
UXUS97 KBOU 091332
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0631 MST Saturday, November 9, 2024
This forecast is for Saturday, November 9, 2024:
If the trigger temperature of 44.8 F/7.1 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 8317 ft MSL (3000 ft AGL)
Forecast maximum temperature................... 42.0 F/6.0 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 6444 ft MSL (1127 ft AGL)
Thermal soaring outlook for Sunday 11/10....... Poor
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... Slight increase
Height of stable layer (12-18K ft MSL)......... 11948 ft MSL (6631 ft AGL)
Weak PVA/NVA (through 1700 MST)................ Weak NVA
Potential height of wave....................... 12439 ft MSL (7122 ft AGL)
Wave soaring outlook for Sunday 11/10.......... Fair
Remarks... Snow ending today, weak mountain wave develops tonight.
Sunrise/Sunset.................... 06:38:12 / 16:48:27 MST
Total possible sunshine........... 10 hr 10 min 15 sec (610 min 15 sec)
Altitude of sun at 11:43:20 MST... 32.94 degrees
Upper air data from numerical model forecast valid on 11/09/2024 at 0500 MST
Freezing level.................. 5679 ft MSL (362 ft AGL)
Convective condensation level... 8647 ft MSL (3330 ft AGL)
Lifted condensation level....... 8486 ft MSL (3169 ft AGL)
Lifted index.................... +8.9
K index......................... +15.7
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 -61.1 -78.0 240 24 13 3.2 1.8 M M M M M
45000 -55.5 -67.9 250 26 14 7.1 3.9 M M M M M
40000 -44.3 -47.7 265 32 17 7.1 3.9 M M M M M
38000 -40.1 -40.2 270 33 17 7.0 3.8 M M M M M
36000 -35.9 -32.6 280 34 18 7.0 3.8 M M M M M
34000 -32.6 -26.7 285 33 17 0.8 0.4 M M M M M
32000 -32.3 -26.1 315 25 13 0.6 0.3 M M M M M
30000 -32.0 -25.6 345 26 13 -0.8 -0.5 48.7 119.6 32.3 M M
29000 -32.4 -26.3 360 32 16 -0.9 -0.5 43.2 109.7 28.6 M M
28000 -32.6 -26.7 005 38 19 -0.9 -0.5 39.0 102.3 25.8 M M
27000 -32.9 -27.2 010 43 22 -0.7 -0.4 35.1 95.2 23.0 M M
26000 -32.2 -26.0 010 45 23 3.2 1.8 32.2 90.0 21.0 M M
25000 -31.2 -24.2 010 46 24 3.2 1.8 29.7 85.5 19.3 M M
24000 -30.3 -22.5 005 47 24 2.9 1.6 27.4 81.3 17.6 M M
23000 -28.4 -19.1 005 46 24 8.0 4.4 26.1 79.0 16.8 M M
22000 -26.0 -14.8 005 45 23 8.1 4.4 25.5 77.9 16.4 M M
21000 -23.6 -10.5 005 44 23 8.0 4.4 25.0 76.9 16.1 M M
20000 -21.3 -6.3 005 43 22 7.7 4.2 24.2 75.5 15.6 M M
19500 -20.2 -4.4 005 42 22 7.7 4.2 23.8 74.9 15.4 M M
19000 -19.0 -2.2 005 41 21 7.7 4.2 23.5 74.2 15.2 M M
18500 -17.9 -0.2 010 41 21 7.8 4.3 23.2 73.7 15.0 M M
18000 -16.8 1.8 010 40 21 6.7 3.7 22.7 72.9 14.7 M M
17500 -15.8 3.6 010 39 20 6.8 3.7 22.2 72.0 14.3 M M
17000 -14.9 5.2 010 37 19 6.2 3.4 21.7 71.1 13.9 M M
16500 -14.1 6.6 010 36 19 5.6 3.1 21.0 69.8 13.3 M M
16000 -12.8 9.0 010 34 17 5.7 3.1 20.0 67.9 12.4 M M
15500 -12.0 10.4 010 32 16 5.8 3.2 19.3 66.7 11.9 M M
15000 -11.1 12.0 010 30 15 5.7 3.1 18.6 65.5 11.4 M M
14500 -10.3 13.5 010 28 15 5.4 3.0 17.9 64.2 10.7 M M
14000 -9.6 14.7 010 27 14 5.2 2.9 17.2 63.0 10.1 M M
13500 -9.0 15.8 005 27 14 2.8 1.5 16.2 61.2 9.3 M M
13000 -8.6 16.5 360 27 14 3.0 1.7 15.1 59.2 8.3 M M
12500 -8.3 17.1 350 28 14 1.1 0.6 13.9 56.9 7.2 M M
12000 -8.1 17.4 345 29 15 1.0 0.5 12.5 54.5 6.0 M M
11500 -7.7 18.1 340 29 15 4.4 2.4 11.4 52.5 4.9 M M
11000 -7.1 19.2 335 29 15 4.1 2.2 10.5 50.8 4.1 M M
10500 -6.5 20.3 335 29 15 3.9 2.1 9.5 49.1 3.2 M M
10250 -6.3 20.7 335 28 15 3.2 1.8 9.0 48.3 2.8 M M
10000 -6.0 21.2 335 28 15 5.8 3.2 8.6 47.5 2.3 M M
9750 -5.5 22.1 340 26 13 6.6 3.6 8.4 47.1 2.1 M M
9500 -5.1 22.8 340 25 13 4.5 2.5 8.0 46.4 1.8 M M
9250 -4.7 23.5 345 24 13 5.4 2.9 7.6 45.7 1.4 M M
9000 -4.4 24.1 345 24 12 4.0 2.2 7.3 45.1 1.0 M M
8750 -4.1 24.6 345 24 12 4.5 2.5 6.8 44.2 0.6 M M
8500 -3.7 25.3 350 24 12 6.0 3.3 6.5 43.6 0.2 M M
8250 -3.3 26.1 355 23 12 5.8 3.2 6.2 43.1 -0.1 202 1.0
8000 -2.9 26.8 355 23 12 4.5 2.5 5.8 42.5 -0.4 182 0.9
7750 -2.6 27.3 355 23 12 4.4 2.4 5.4 41.7 -0.8 167 0.8
7500 -2.2 28.0 360 23 12 6.0 3.3 5.1 41.1 -1.2 147 0.7
7250 -1.8 28.8 360 23 12 4.9 2.7 4.7 40.5 -1.5 128 0.6
7000 -1.5 29.3 360 23 12 2.9 1.6 4.3 39.8 -1.9 112 0.6
6750 -1.3 29.7 360 23 12 3.8 2.1 3.8 38.8 -2.5 98 0.5
6500 -1.0 30.2 355 21 11 5.5 3.0 3.4 38.2 -2.8 80 0.4
6250 -0.6 30.9 350 18 9 3.6 1.9 3.0 37.5 -3.2 62 0.3
6000 -0.4 31.3 350 16 8 1.6 0.9 2.5 36.5 -3.8 50 0.3
5750 -0.3 31.5 345 13 7 4.6 2.5 1.9 35.5 -4.4 37 0.2
5500 0.2 32.4 335 10 5 8.5 4.7 1.7 35.1 -4.6 14 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/09/2024 at 0800 MST | 11/09/2024 at 1100 MST
|
CAPE... +0.3 LI... +4.1 | CAPE... +2.4 LI... +3.0
CINH... -0.1 K Index... +16.8 | CINH... -0.2 K Index... +17.2
|
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 -60.5 -76.9 225 28 15 2.5 1.4 | -60.4 -76.7 225 34 18 2.5 1.4
45000 -55.9 -68.6 235 33 17 7.0 3.8 | -55.9 -68.6 225 29 15 6.2 3.4
40000 -45.4 -49.7 240 31 16 7.0 3.8 | -46.5 -51.7 235 34 17 6.3 3.4
38000 -41.2 -42.2 250 31 16 7.0 3.8 | -42.6 -44.7 240 32 16 6.4 3.5
36000 -36.5 -33.7 265 33 17 7.0 3.8 | -38.3 -36.9 255 29 15 6.4 3.5
34000 -33.5 -28.3 280 32 16 0.6 0.4 | -35.8 -32.4 275 25 13 -0.3 -0.2
32000 -33.1 -27.6 315 28 14 0.5 0.3 | -36.0 -32.8 325 26 14 -0.4 -0.2
30000 -32.9 -27.2 345 33 17 0.0 0.0 | -35.9 -32.6 350 41 21 3.1 1.7
29000 -32.8 -27.0 350 36 19 0.1 0.0 | -35.0 -31.0 355 48 25 3.0 1.6
28000 -32.8 -27.0 355 41 21 0.1 0.0 | -34.1 -29.4 355 55 28 3.0 1.7
27000 -32.8 -27.0 360 45 23 -0.4 -0.2 | -33.2 -27.8 360 62 32 3.2 1.8
26000 -31.9 -25.4 360 47 24 3.9 2.1 | -31.5 -24.7 355 62 32 6.0 3.3
25000 -30.8 -23.4 360 48 25 3.9 2.1 | -29.8 -21.6 355 60 31 6.0 3.3
24000 -29.6 -21.3 355 49 25 3.8 2.1 | -28.0 -18.4 350 58 30 6.0 3.3
23000 -27.9 -18.2 355 49 25 7.0 3.9 | -26.1 -15.0 350 55 28 6.1 3.4
22000 -25.8 -14.4 355 47 24 7.1 3.9 | -24.3 -11.7 350 52 27 6.1 3.4
21000 -23.6 -10.5 355 46 24 7.1 3.9 | -22.5 -8.5 350 48 25 6.1 3.4
20000 -21.6 -6.9 355 44 23 6.9 3.8 | -20.7 -5.3 350 44 23 6.1 3.4
19500 -20.6 -5.1 355 43 22 7.0 3.8 | -19.8 -3.6 350 42 22 6.1 3.4
19000 -19.0 -2.2 355 41 21 7.0 3.8 | -18.9 -2.0 350 40 20 6.2 3.4
18500 -18.0 -0.4 355 40 21 6.6 3.6 | -18.5 -1.3 350 38 19 6.2 3.4
18000 -17.1 1.2 355 38 20 5.6 3.1 | -16.7 1.9 350 35 18 5.6 3.1
17500 -16.3 2.7 355 37 19 5.7 3.1 | -15.9 3.4 345 33 17 5.5 3.0
17000 -15.5 4.1 355 35 18 5.8 3.2 | -15.0 5.0 345 32 16 6.4 3.5
16500 -14.6 5.7 350 33 17 5.9 3.2 | -14.1 6.6 345 31 16 6.4 3.5
16000 -13.8 7.2 350 31 16 6.5 3.6 | -13.1 8.4 345 30 15 6.9 3.8
15500 -12.8 9.0 345 30 16 6.9 3.8 | -12.1 10.2 340 29 15 7.1 3.9
15000 -11.7 10.9 345 29 15 6.9 3.8 | -11.1 12.0 340 28 15 6.9 3.8
14500 -10.8 12.6 345 29 15 6.5 3.6 | -10.1 13.8 335 28 15 6.4 3.5
14000 -9.8 14.4 345 29 15 6.5 3.5 | -9.2 15.4 330 28 15 6.3 3.5
13500 -9.1 15.6 340 29 15 3.5 1.9 | -8.3 17.1 330 29 15 5.7 3.1
13000 -8.6 16.5 340 29 15 3.6 2.0 | -7.5 18.5 330 29 15 5.7 3.1
12500 -8.0 17.6 340 28 15 5.0 2.7 | -6.6 20.1 325 30 15 5.6 3.1
12000 -7.2 19.0 335 28 14 5.1 2.8 | -5.8 21.6 325 29 15 5.7 3.1
11500 -6.7 19.9 335 27 14 3.0 1.7 | -5.1 22.8 325 29 15 3.8 2.1
11000 -6.2 20.8 330 27 14 3.3 1.8 | -4.5 23.9 320 29 15 4.0 2.2
10500 -5.8 21.6 330 27 14 2.5 1.3 | -4.0 24.8 320 27 14 3.6 2.0
10250 -5.6 21.9 330 26 14 1.9 1.0 | -3.7 25.3 320 27 14 2.8 1.5
10000 -5.4 22.3 330 26 14 4.4 2.4 | -3.5 25.7 315 26 13 6.0 3.3
9750 -5.0 23.0 330 24 13 5.6 3.1 | -2.9 26.8 315 25 13 6.8 3.7
9500 -4.7 23.5 330 23 12 3.8 2.1 | -2.6 27.3 315 24 12 4.0 2.2
9250 -4.3 24.3 330 23 12 4.4 2.4 | -2.2 28.0 315 23 12 5.2 2.8
9000 -4.0 24.8 330 22 11 3.6 2.0 | -1.9 28.6 315 21 11 3.3 1.8
8750 -3.8 25.2 335 22 11 4.4 2.4 | -1.7 28.9 310 19 10 3.5 1.9
8500 -3.4 25.9 335 21 11 5.5 3.0 | -1.3 29.7 315 18 9 5.2 2.9
8250 -3.0 26.6 340 20 10 5.4 3.0 | -0.9 30.4 315 17 9 5.1 2.8
8000 -2.6 27.3 345 20 10 4.9 2.7 | -0.6 30.9 315 15 8 3.6 1.9
7750 -2.3 27.9 345 21 11 5.2 2.8 | -0.4 31.3 320 14 7 2.5 1.4
7500 -1.9 28.6 350 20 10 6.2 3.4 | -0.2 31.6 325 12 6 3.4 1.9
7250 -1.4 29.5 350 20 10 5.4 3.0 | 0.1 32.2 325 11 6 3.1 1.7
7000 -1.1 30.0 355 20 10 3.6 2.0 | 0.3 32.5 335 10 5 2.5 1.4
6750 -0.8 30.6 355 20 10 4.2 2.3 | 0.5 32.9 340 9 5 3.2 1.7
6500 -0.5 31.1 350 17 9 5.8 3.2 | 0.7 33.3 340 8 4 4.0 2.2
6250 -0.1 31.8 350 15 7 4.2 2.3 | 1.0 33.8 340 6 3 4.0 2.2
6000 0.1 32.2 340 12 6 2.7 1.5 | 1.2 34.2 330 4 2 3.3 1.8
5750 0.4 32.7 335 9 5 4.7 2.6 | 1.5 34.7 310 2 1 6.0 3.3
5500 0.8 33.4 315 6 3 5.6 3.1 | 2.1 35.8 265 2 1 11.4 6.2
11/09/2024 at 1400 MST | 11/09/2024 at 1700 MST
|
CAPE... +0.3 LI... +4.1 | CAPE... 0.0 LI... +4.1
CINH... -0.1 K Index... +15.3 | CINH... 0.0 K Index... +16.3
|
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 -60.1 -76.2 230 31 16 2.9 1.6 | -60.5 -76.9 250 36 18 2.8 1.5
45000 -55.3 -67.5 225 29 15 5.4 3.0 | -55.7 -68.3 250 40 21 5.1 2.8
40000 -47.1 -52.8 245 30 15 5.4 3.0 | -47.9 -54.2 260 34 17 5.1 2.8
38000 -44.7 -48.5 255 30 15 3.6 2.0 | -46.9 -52.4 270 34 17 0.2 0.1
36000 -42.5 -44.5 270 30 16 3.6 2.0 | -46.8 -52.2 285 36 18 0.2 0.1
34000 -40.7 -41.3 290 30 15 0.4 0.2 | -46.1 -51.0 295 38 20 4.2 2.3
32000 -40.5 -40.9 335 37 19 0.3 0.2 | -43.3 -45.9 320 41 21 4.2 2.3
30000 -39.3 -38.7 350 51 26 6.9 3.8 | -39.8 -39.6 330 45 23 9.0 4.9
29000 -37.2 -35.0 350 53 27 7.1 3.9 | -37.1 -34.8 330 46 24 9.0 4.9
28000 -35.1 -31.2 345 56 29 7.1 3.9 | -34.4 -29.9 330 47 24 9.0 4.9
27000 -32.9 -27.2 345 59 30 7.1 3.9 | -31.8 -25.2 335 48 25 8.1 4.4
26000 -30.8 -23.4 345 57 29 7.1 3.9 | -29.4 -20.9 335 48 24 7.8 4.3
25000 -28.7 -19.7 340 55 28 7.1 3.9 | -27.1 -16.8 335 47 24 7.8 4.3
24000 -26.6 -15.9 340 53 27 7.2 3.9 | -24.8 -12.6 335 47 24 7.4 4.1
23000 -24.7 -12.5 335 50 26 6.1 3.4 | -22.8 -9.0 335 46 24 6.4 3.5
22000 -22.9 -9.2 335 47 24 6.2 3.4 | -20.9 -5.6 335 45 23 6.4 3.5
21000 -21.1 -6.0 330 44 22 6.3 3.4 | -19.1 -2.4 335 44 23 5.8 3.2
20000 -19.2 -2.6 330 40 21 6.6 3.6 | -17.5 0.5 335 43 22 5.3 2.9
19500 -18.2 -0.8 330 39 20 6.6 3.6 | -16.7 1.9 335 42 22 5.3 2.9
19000 -17.2 1.0 325 37 19 6.6 3.6 | -15.9 3.4 335 41 21 5.4 3.9
18500 -16.3 2.7 325 35 18 6.6 3.6 | -15.2 4.6 335 40 21 5.6 3.1
18000 -15.3 4.5 325 34 17 6.3 3.5 | -14.3 6.3 335 40 20 6.4 3.5
17500 -13.9 7.0 325 31 16 6.4 3.5 | -13.3 8.1 335 39 20 6.4 3.5
17000 -12.9 8.8 325 30 16 6.9 3.8 | -12.4 9.7 335 38 20 6.1 3.3
16500 -11.9 10.6 325 30 15 6.9 3.8 | -11.1 12.0 335 39 20 6.1 3.4
16000 -10.9 12.4 325 30 15 6.3 3.4 | -10.2 13.6 335 39 20 5.6 3.1
15500 -10.0 14.0 325 30 15 6.1 3.3 | -9.4 15.1 335 40 21 5.6 3.1
15000 -9.1 15.6 325 30 16 5.2 2.9 | -8.6 16.5 335 41 21 5.2 2.8
14500 -8.5 16.7 325 31 16 4.2 2.3 | -7.9 17.8 335 41 21 5.0 2.8
14000 -7.9 17.8 325 32 17 4.1 2.3 | -7.1 19.2 335 42 21 5.1 2.8
13500 -7.3 18.9 325 33 17 4.0 2.2 | -6.4 20.5 335 41 21 5.1 2.8
13000 -6.8 19.8 325 34 17 4.1 2.2 | -5.6 21.9 335 41 21 5.2 2.8
12500 -6.0 21.2 325 34 17 5.8 3.2 | -4.9 23.2 335 40 21 5.4 2.9
12000 -5.2 22.6 320 33 17 5.6 3.1 | -4.1 24.6 335 40 20 5.5 3.0
11500 -4.4 24.1 320 32 16 5.4 3.0 | -3.2 26.2 330 38 20 5.8 3.2
11000 -3.5 25.7 320 31 16 5.4 3.0 | -2.4 27.7 330 37 19 5.5 3.0
10500 -2.9 26.8 315 30 15 3.9 2.2 | -1.6 29.1 330 35 18 4.5 2.5
10250 -2.6 27.3 315 29 15 3.0 1.6 | -1.3 29.7 330 35 18 5.1 2.8
10000 -2.3 27.9 310 29 15 7.9 4.3 | -0.8 30.6 325 34 18 10.0 5.5
9750 -1.5 29.3 310 28 14 9.7 5.3 | 0.1 32.2 325 33 17 9.8 5.4
9500 -1.0 30.2 310 27 14 6.0 3.3 | 0.6 33.1 325 32 16 6.4 3.5
9250 -0.5 31.1 310 26 14 7.5 4.1 | 1.2 34.2 325 31 16 7.8 4.3
9000 0.1 32.2 305 25 13 5.2 2.8 | 1.7 35.1 320 29 15 5.8 3.2
8750 0.4 32.7 305 25 13 5.0 2.7 | 2.1 35.8 320 28 14 6.4 3.5
8500 0.9 33.6 305 24 12 6.7 3.7 | 2.7 36.9 320 26 13 8.7 4.8
8250 1.3 34.3 305 22 12 6.9 3.8 | 3.4 38.1 315 25 13 7.8 4.3
8000 1.8 35.2 305 21 11 4.3 2.4 | 3.9 39.0 315 23 12 5.0 2.7
7750 2.0 35.6 305 19 10 1.6 0.9 | 4.2 39.6 310 22 11 4.4 2.4
7500 2.1 35.8 305 16 8 2.5 1.4 | 4.6 40.3 310 20 10 6.3 3.4
7250 2.3 36.1 305 13 7 1.7 1.0 | 5.0 41.0 310 18 9 4.4 2.4
7000 2.3 36.1 305 10 5 0.1 0.1 | 5.2 41.4 305 16 8 2.7 1.5
6750 2.3 36.1 305 8 4 -0.4 -0.2 | 5.4 41.7 305 14 7 1.5 0.8
6500 2.2 36.0 310 6 3 -0.3 -0.2 | 5.4 41.7 300 11 5 -0.0 -0.0
6250 2.2 36.0 310 4 2 0.2 0.1 | 5.2 41.4 285 8 4 -4.3 -2.4
6000 2.2 36.0 295 2 1 -0.2 -0.1 | 4.7 40.5 260 6 3 -7.0 -3.9
5750 2.2 36.0 225 1 1 2.4 1.3 | 4.2 39.6 230 6 3 -6.9 -3.8
5500 2.5 36.5 200 1 1 7.3 4.0 | 3.4 38.1 205 8 4 -15.4 -8.5
________________________________________________________________________________
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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