Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
432
UXUS97 KBOU 120107
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1907 MDT Saturday, May 11, 2024
This forecast is for Sunday, May 12, 2024:
If the trigger temperature of 56.7 F/13.7 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 645 ft/min (3.3 m/s)
Maximum height of thermals.................. 13588 ft MSL (8296 ft AGL)
Forecast maximum temperature................... 66.0 F/19.3 C
Time of trigger temperature.................... 1030 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................. 10981 ft MSL (5690 ft AGL)
Thermal soaring outlook for Monday 05/13....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Remaining poor.
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 16614 ft MSL (11322 ft AGL)
Wave soaring outlook for Monday 05/13.......... Poor
Remarks... Scattered morning showers, followed by scattered afternoon showers
and storms
Sunrise/Sunset.................... 05:46:46 / 20:04:54 MDT
Total possible sunshine........... 14 hr 18 min 8 sec (858 min 8 sec)
Altitude of sun at 12:55:50 MDT... 68.62 degrees
Upper air data from numerical model forecast valid on 05/12/2024 at 0600 MDT
Freezing level.................. 10145 ft MSL (4853 ft AGL)
Convective condensation level... 9015 ft MSL (3723 ft AGL)
Lifted condensation level....... 11220 ft MSL (5928 ft AGL)
Lifted index.................... -2.4
K index......................... +25.2
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 -55.7 -68.3 310 16 8 2.0 1.1 M M M M M
45000 -52.6 -62.7 295 15 8 1.4 0.8 M M M M M
40000 -50.4 -58.7 280 16 8 1.5 0.8 M M M M M
38000 -50.5 -58.9 285 10 5 -1.4 -0.8 M M M M M
36000 -51.4 -60.5 015 4 2 -1.4 -0.8 M M M M M
34000 -51.5 -60.7 060 12 6 6.6 3.6 M M M M M
32000 -48.0 -54.4 055 16 8 5.9 3.2 M M M M M
30000 -43.4 -46.1 055 18 10 9.3 5.1 31.9 89.4 9.8 M M
29000 -40.6 -41.1 060 18 9 9.3 5.1 31.6 88.9 9.7 M M
28000 -37.8 -36.0 065 18 9 9.3 5.1 31.5 88.7 9.7 M M
27000 -35.0 -31.0 070 18 9 9.0 4.9 31.4 88.6 9.8 M M
26000 -32.4 -26.3 070 19 10 8.8 4.8 31.0 87.7 9.5 M M
25000 -29.8 -21.6 070 19 10 8.8 4.8 30.6 87.1 9.3 M M
24000 -27.2 -17.0 075 20 10 8.5 4.7 30.4 86.7 9.2 M M
23000 -24.8 -12.6 070 21 11 7.9 4.3 29.6 85.4 8.7 M M
22000 -22.5 -8.5 070 22 12 7.9 4.4 29.0 84.2 8.2 M M
21000 -20.1 -4.2 070 24 12 7.1 3.9 28.4 83.1 7.8 M M
20000 -18.1 -0.6 065 25 13 6.7 3.7 27.2 81.0 6.8 M M
19500 -17.2 1.0 065 26 13 6.7 3.7 26.7 80.1 6.4 M M
19000 -16.2 2.8 060 27 14 6.7 3.7 26.2 79.2 6.0 M M
18500 -15.2 4.6 060 27 14 6.6 3.6 25.7 78.3 5.6 M M
18000 -14.3 6.3 060 28 14 6.1 3.4 25.1 77.2 5.1 M M
17500 -13.4 7.9 055 29 15 6.2 3.4 24.5 76.1 4.5 M M
17000 -12.5 9.5 055 29 15 6.1 3.4 23.9 75.0 4.0 M M
16500 -11.6 11.1 050 30 15 6.1 3.4 23.3 73.9 3.4 M M
16000 -10.7 12.7 045 30 16 5.9 3.3 22.7 72.8 2.9 M M
15500 -9.4 15.1 045 31 16 5.7 3.1 21.6 70.9 2.0 M M
15000 -8.6 16.5 040 31 16 6.3 3.5 21.0 69.8 1.4 M M
14500 -7.6 18.3 040 31 16 6.4 3.5 20.4 68.8 0.9 M M
14000 -6.7 19.9 035 31 16 6.4 3.5 19.9 67.9 0.4 M M
13500 -5.8 21.6 035 31 16 6.4 3.5 19.4 66.8 -0.2 630 3.2
13000 -4.8 23.4 030 31 16 6.4 3.5 18.8 65.9 -0.7 588 3.0
12500 -3.9 25.0 030 31 16 6.5 3.6 18.3 64.9 -1.3 545 2.8
12000 -3.0 26.6 030 31 16 6.3 3.5 17.8 64.0 -1.8 502 2.6
11500 -2.1 28.2 025 31 16 5.9 3.2 17.1 62.9 -2.4 462 2.3
11000 -1.3 29.7 025 30 16 5.7 3.1 16.5 61.8 -3.0 422 2.1
10500 -0.5 31.1 020 29 15 4.9 2.7 15.8 60.5 -3.8 384 2.0
10250 -0.1 31.8 020 29 15 5.9 3.2 15.5 59.8 -4.1 365 1.9
10000 0.4 32.7 020 28 14 7.9 4.3 15.2 59.4 -4.4 343 1.7
9750 0.9 33.6 020 27 14 7.7 4.2 15.1 59.2 -4.5 318 1.6
9500 1.4 34.5 015 26 13 7.0 3.8 14.9 58.8 -4.8 296 1.5
9250 2.0 35.6 015 25 13 7.3 4.0 14.7 58.4 -5.0 273 1.4
9000 2.5 36.5 015 24 12 6.4 3.5 14.5 58.1 -5.2 251 1.3
8750 2.9 37.2 010 23 12 6.6 3.6 14.2 57.6 -5.5 230 1.2
8500 3.4 38.1 010 22 11 7.5 4.1 14.0 57.2 -5.8 207 1.1
8250 3.9 39.0 005 21 11 7.0 3.8 13.8 56.9 -6.0 184 0.9
8000 4.4 39.9 005 20 10 5.9 3.2 13.6 56.4 -6.3 163 0.8
7750 4.8 40.6 360 19 10 5.9 3.3 13.3 55.9 -6.6 144 0.7
7500 5.3 41.5 360 18 9 7.1 3.9 13.0 55.4 -6.9 122 0.6
7250 5.7 42.3 355 18 9 5.4 3.0 12.8 55.0 -7.2 101 0.5
7000 6.0 42.8 350 17 8 3.2 1.7 12.3 54.2 -7.6 84 0.4
6750 6.3 43.3 350 15 8 4.7 2.6 11.9 53.4 -8.1 69 0.4
6500 6.7 44.1 345 14 7 5.7 3.1 11.6 52.8 -8.4 50 0.3
6250 7.0 44.6 340 13 7 3.5 1.9 11.2 52.1 -8.9 32 0.2
6000 7.2 45.0 335 12 6 2.0 1.1 10.6 51.2 -9.4 19 0.1
5750 7.4 45.3 325 11 6 4.0 2.2 10.1 50.2 -10.0 5 0.0
5500 7.9 46.2 320 9 4 8.0 4.4 9.8 49.7 -10.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/12/2024 at 0900 MDT | 05/12/2024 at 1200 MDT
|
CAPE... +61.8 LI... -0.9 | CAPE... +255.9 LI... -1.3
CINH... -33.7 K Index... +23.8 | CINH... -4.1 K Index... +21.2
|
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 -55.6 -68.1 310 16 8 2.8 1.6 | -55.4 -67.7 305 18 9 3.0 1.6
45000 -51.4 -60.5 315 13 7 0.7 0.4 | -51.1 -60.0 310 16 8 0.7 0.4
40000 -50.2 -58.4 300 9 5 0.8 0.4 | -49.9 -57.8 295 10 5 0.8 0.5
38000 -50.2 -58.4 335 7 4 -0.5 -0.3 | -50.2 -58.4 340 7 4 -1.5 -0.8
36000 -50.5 -58.9 025 14 7 -0.5 -0.3 | -51.1 -60.0 030 16 8 -1.5 -0.8
34000 -50.4 -58.7 040 22 11 5.1 2.8 | -50.9 -59.6 040 26 13 5.7 3.1
32000 -47.3 -53.1 045 25 13 4.6 2.5 | -47.4 -53.3 045 26 13 5.9 3.2
30000 -43.8 -46.8 050 27 14 9.0 4.9 | -43.3 -45.9 045 26 14 8.9 4.9
29000 -41.1 -42.0 050 27 14 9.1 5.0 | -40.7 -41.3 045 26 13 9.0 4.9
28000 -38.3 -36.9 050 27 14 9.1 5.0 | -38.0 -36.4 045 25 13 9.0 4.9
27000 -35.6 -32.1 050 26 14 8.6 4.7 | -35.3 -31.5 045 25 13 8.6 4.7
26000 -33.1 -27.6 050 26 13 8.3 4.6 | -32.8 -27.0 045 24 12 8.4 4.6
25000 -30.7 -23.3 055 25 13 8.3 4.6 | -30.3 -22.5 045 23 12 8.4 4.6
24000 -28.2 -18.8 055 25 13 8.1 4.5 | -27.7 -17.9 045 22 11 7.9 4.3
23000 -25.9 -14.6 055 25 13 7.6 4.2 | -25.7 -14.3 040 22 12 6.9 3.8
22000 -23.7 -10.7 055 24 13 7.6 4.2 | -23.6 -10.5 040 23 12 6.9 3.8
21000 -21.4 -6.5 055 24 13 6.9 3.8 | -21.6 -6.9 040 24 12 6.7 3.7
20000 -19.5 -3.1 050 25 13 6.5 3.6 | -19.6 -3.3 035 25 13 6.6 3.6
19500 -18.5 -1.3 050 26 13 6.5 3.6 | -18.6 -1.5 035 26 14 6.6 3.6
19000 -17.6 0.3 050 27 14 6.5 3.6 | -17.6 0.3 030 27 14 6.6 3.6
18500 -16.6 2.1 050 27 14 6.5 3.6 | -16.6 2.1 030 28 14 6.4 3.5
18000 -15.6 3.9 050 27 14 6.6 3.6 | -15.7 3.7 030 28 15 6.3 3.4
17500 -14.2 6.4 045 28 14 6.8 3.7 | -14.7 5.5 025 29 15 6.3 3.5
17000 -13.1 8.4 040 28 14 7.0 3.8 | -13.5 7.7 025 29 15 5.5 3.0
16500 -12.1 10.2 040 27 14 7.0 3.8 | -12.7 9.1 025 29 15 5.5 3.0
16000 -11.1 12.0 035 27 14 6.9 3.8 | -11.8 10.8 020 29 15 6.7 3.7
15500 -10.1 13.8 035 27 14 6.9 3.8 | -10.8 12.6 020 29 15 6.5 3.6
15000 -9.1 15.6 035 27 14 6.6 3.6 | -9.8 14.4 020 29 15 7.7 4.2
14500 -8.2 17.2 030 27 14 6.6 3.6 | -8.7 16.3 015 29 15 7.7 4.2
14000 -7.2 19.0 030 27 14 6.7 3.7 | -7.6 18.3 015 29 15 8.1 4.4
13500 -6.3 20.7 030 27 14 6.8 3.7 | -6.4 20.5 010 29 15 8.2 4.5
13000 -5.3 22.5 025 27 14 6.8 3.7 | -5.2 22.6 010 28 15 8.5 4.7
12500 -4.3 24.3 025 27 14 6.8 3.7 | -4.0 24.8 010 28 14 8.7 4.7
12000 -3.4 25.9 025 28 14 7.0 3.9 | -2.7 27.1 010 27 14 8.7 4.8
11500 -2.3 27.9 025 28 14 7.5 4.1 | -1.4 29.5 010 25 13 8.8 4.8
11000 -1.2 29.8 020 28 14 7.3 4.0 | -0.2 31.6 010 24 12 8.0 4.4
10500 -0.2 31.6 020 28 14 6.3 3.5 | 0.9 33.6 010 23 12 6.3 3.5
10250 0.3 32.5 020 28 14 9.0 4.9 | 1.4 34.5 010 23 12 11.0 6.0
10000 1.1 34.0 020 27 14 10.7 5.9 | 2.4 36.3 010 22 11 12.3 6.8
9750 1.8 35.2 020 27 14 8.8 4.8 | 3.1 37.6 010 21 11 8.4 4.6
9500 2.4 36.3 020 26 14 8.9 4.9 | 3.8 38.8 010 21 11 9.9 5.4
9250 3.1 37.6 020 26 13 8.5 4.7 | 4.5 40.1 015 20 10 7.9 4.4
9000 3.7 38.7 020 26 13 7.5 4.1 | 5.0 41.0 015 20 10 8.3 4.5
8750 4.2 39.6 020 25 13 8.0 4.4 | 5.8 42.4 015 20 10 10.4 5.7
8500 4.8 40.6 015 24 13 8.7 4.8 | 6.5 43.7 015 19 10 10.4 5.7
8250 5.5 41.9 015 24 12 8.3 4.6 | 7.3 45.1 015 19 10 9.4 5.1
8000 6.1 43.0 015 23 12 7.5 4.1 | 7.9 46.2 020 18 9 8.3 4.5
7750 6.6 43.9 015 23 12 6.9 3.8 | 8.6 47.5 020 18 9 9.5 5.2
7500 7.1 44.8 015 21 11 7.5 4.1 | 9.3 48.7 020 17 9 10.6 5.8
7250 7.6 45.7 010 20 10 5.6 3.1 | 10.1 50.2 025 16 8 8.7 4.8
7000 7.9 46.2 010 19 10 3.2 1.7 | 10.6 51.1 025 16 8 7.1 3.9
6750 8.2 46.8 010 19 10 4.1 2.2 | 11.3 52.3 025 16 8 10.7 5.9
6500 8.5 47.3 005 16 8 4.5 2.4 | 12.2 54.0 025 15 8 12.2 6.7
6250 8.8 47.8 005 13 7 4.0 2.2 | 13.0 55.4 030 15 8 10.2 5.6
6000 9.1 48.4 360 11 5 3.2 1.8 | 13.7 56.7 030 14 7 9.8 5.4
5750 9.3 48.7 355 8 4 5.6 3.1 | 14.4 57.9 030 14 7 9.8 5.4
5500 9.9 49.8 345 6 3 11.9 6.5 | 15.3 59.5 035 12 6 14.4 7.9
05/12/2024 at 1500 MDT | 05/12/2024 at 1800 MDT
|
CAPE... +412.5 LI... -1.8 | CAPE... +128.9 LI... -0.8
CINH... -8.1 K Index... +25.9 | CINH... -34.8 K Index... +24.1
|
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 -55.2 -67.4 295 17 9 3.0 1.7 | -55.6 -68.1 290 20 10 2.6 1.4
45000 -51.0 -59.8 305 15 8 0.2 0.1 | -51.9 -61.4 300 16 8 0.2 0.1
40000 -50.5 -58.9 305 13 7 0.3 0.2 | -51.6 -60.9 315 15 8 0.2 0.1
38000 -51.1 -60.0 330 12 6 -1.8 -1.0 | -51.7 -61.1 330 14 7 -0.6 -0.3
36000 -52.2 -62.0 005 14 7 -1.8 -1.0 | -52.2 -62.0 355 16 8 -0.6 -0.4
34000 -51.9 -61.4 020 18 9 7.1 3.9 | -51.0 -59.8 010 17 9 7.0 3.9
32000 -47.4 -53.3 015 18 9 7.4 4.1 | -46.8 -52.2 010 15 7 7.1 3.9
30000 -42.7 -44.9 010 18 9 8.8 4.8 | -42.2 -44.0 010 14 7 8.6 4.7
29000 -40.1 -40.2 010 18 9 8.9 4.9 | -39.6 -39.3 005 16 8 8.6 4.7
28000 -37.4 -35.3 010 18 9 8.9 4.9 | -37.1 -34.8 360 18 9 8.6 4.7
27000 -34.8 -30.6 010 18 9 8.4 4.6 | -34.5 -30.1 355 20 10 8.2 4.5
26000 -31.9 -25.4 010 17 9 7.8 4.3 | -32.1 -25.8 360 21 11 8.1 4.5
25000 -29.6 -21.3 005 17 9 7.8 4.3 | -29.6 -21.3 005 22 11 8.2 4.5
24000 -27.3 -17.1 360 17 9 7.4 4.1 | -27.2 -17.0 010 23 12 7.8 4.3
23000 -25.1 -13.2 005 21 11 7.3 4.0 | -25.0 -13.0 010 24 12 7.5 4.1
22000 -22.9 -9.2 010 25 13 7.3 4.0 | -22.7 -8.9 010 25 13 7.5 4.1
21000 -20.7 -5.3 010 28 14 7.0 3.8 | -20.5 -4.9 010 26 13 7.3 4.0
20000 -18.6 -1.5 005 29 15 7.0 3.9 | -18.4 -1.1 010 27 14 7.2 4.0
19500 -17.5 0.5 005 30 15 7.0 3.9 | -17.3 0.9 005 28 14 7.2 4.0
19000 -16.5 2.3 005 30 16 7.1 3.9 | -16.2 2.8 005 28 15 7.2 4.0
18500 -15.5 4.1 005 31 16 5.9 3.2 | -15.1 4.8 005 29 15 7.0 3.9
18000 -14.7 5.5 005 32 16 5.5 3.0 | -14.1 6.6 005 30 15 6.9 3.8
17500 -13.9 7.0 005 33 17 5.5 3.0 | -12.6 9.3 360 31 16 6.7 3.7
17000 -13.2 8.2 005 33 17 5.0 2.7 | -11.6 11.1 360 31 16 6.6 3.6
16500 -12.5 9.5 005 33 17 4.9 2.7 | -10.7 12.7 360 32 16 6.6 3.6
16000 -11.6 11.1 005 33 17 7.7 4.2 | -9.7 14.5 360 33 17 6.8 3.7
15500 -10.5 13.1 005 33 17 8.0 4.4 | -8.7 16.3 360 33 17 6.7 3.7
15000 -9.3 15.3 005 32 17 8.4 4.6 | -7.7 18.1 360 34 18 7.5 4.1
14500 -8.1 17.4 005 31 16 8.7 4.8 | -6.6 20.1 355 34 18 7.4 4.1
14000 -6.8 19.8 005 31 16 8.7 4.8 | -5.5 22.1 355 34 18 8.0 4.4
13500 -5.6 21.9 005 29 15 8.7 4.8 | -4.3 24.3 355 34 17 8.1 4.4
13000 -3.7 25.3 005 27 14 8.4 4.6 | -3.2 26.2 355 33 17 7.5 4.1
12500 -2.5 27.5 005 26 13 8.4 4.6 | -2.1 28.2 355 31 16 7.2 3.9
12000 -1.3 29.7 005 24 13 7.7 4.2 | -1.1 30.0 355 28 15 7.5 4.1
11500 -0.2 31.6 005 23 12 7.4 4.1 | 0.0 32.0 355 26 13 7.7 4.2
11000 0.8 33.4 010 21 11 7.3 4.0 | 1.1 34.0 355 23 12 7.0 3.8
10500 1.9 35.4 010 20 10 6.4 3.5 | 2.1 35.8 355 21 11 5.6 3.1
10250 2.5 36.5 010 19 10 11.2 6.1 | 2.5 36.5 355 20 10 9.0 5.0
10000 3.5 38.3 015 18 9 11.8 6.5 | 3.3 37.9 355 18 9 10.0 5.5
9750 4.1 39.4 015 16 8 7.2 4.0 | 3.9 39.0 350 17 9 7.0 3.8
9500 4.6 40.3 020 15 8 9.2 5.0 | 4.4 39.9 350 15 8 8.4 4.6
9250 5.2 41.4 020 14 7 5.9 3.2 | 5.0 41.0 345 14 7 6.0 3.3
9000 5.6 42.1 020 13 7 6.1 3.3 | 5.4 41.7 345 13 7 5.9 3.2
8750 6.2 43.2 030 11 6 9.0 5.0 | 5.9 42.6 340 13 6 8.5 4.7
8500 6.8 44.2 035 10 5 8.8 4.8 | 6.6 43.9 335 12 6 8.7 4.8
8250 7.4 45.3 045 9 4 7.1 3.9 | 7.2 45.0 330 11 6 7.8 4.3
8000 7.8 46.0 055 8 4 6.3 3.4 | 7.7 45.9 330 10 5 7.0 3.9
7750 8.4 47.1 065 8 4 9.3 5.1 | 8.3 46.9 325 10 5 8.5 4.7
7500 9.1 48.4 075 8 4 10.5 5.8 | 8.9 48.0 320 9 5 9.3 5.1
7250 9.9 49.8 085 8 4 8.6 4.7 | 9.6 49.3 315 9 5 8.8 4.8
7000 10.4 50.7 090 8 4 7.3 4.0 | 10.2 50.4 315 9 4 8.6 4.7
6750 11.1 52.0 090 8 4 10.8 6.0 | 10.9 51.6 310 9 4 9.5 5.2
6500 12.0 53.6 095 9 5 11.8 6.5 | 11.6 52.9 305 8 4 9.8 5.4
6250 12.7 54.9 100 9 5 9.4 5.2 | 12.3 54.1 300 8 4 9.1 5.0
6000 13.4 56.1 100 9 5 8.4 4.6 | 13.0 55.4 300 8 4 8.7 4.8
5750 14.1 57.4 100 9 5 11.7 6.4 | 13.7 56.7 300 8 4 10.0 5.5
5500 15.2 59.4 105 9 4 19.9 10.9 | 14.5 58.1 295 7 4 13.0 7.1
________________________________________________________________________________
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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