Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
461
UXUS97 KBOU 140013
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1813 MDT Monday, May 13, 2024
This forecast is for Tuesday, May 14, 2024:
If the trigger temperature of 71.3 F/21.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1112 ft/min (5.7 m/s)
Maximum height of thermals.................. 17273 ft MSL (11990 ft AGL)
Forecast maximum temperature................... 79.0 F/26.6 C
Time of trigger temperature.................... 0945 MDT
Time of overdevelopment........................ 1800 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12771 ft MSL (7489 ft AGL)
Thermal soaring outlook for Wednesday 05/15.... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 34882 ft MSL (29599 ft AGL)
Wave soaring outlook for Wednesday 05/15....... Poor
Remarks... Widely scattered afternoon showers and storms
Sunrise/Sunset.................... 05:44:53 / 20:06:48 MDT
Total possible sunshine........... 14 hr 21 min 55 sec (861 min 55 sec)
Altitude of sun at 12:55:50 MDT... 69.10 degrees
Upper air data from numerical model forecast valid on 05/14/2024 at 0600 MDT
Freezing level.................. 12963 ft MSL (7680 ft AGL)
Convective condensation level... 15878 ft MSL (10595 ft AGL)
Lifted condensation level....... 16426 ft MSL (11144 ft AGL)
Lifted index.................... -3.2
K index......................... +15.9
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 -56.2 -69.2 265 18 9 2.4 1.3 M M M M M
45000 -53.4 -64.1 275 20 10 -3.7 -2.0 M M M M M
40000 -58.9 -74.0 270 19 10 -3.7 -2.0 M M M M M
38000 -57.5 -71.5 275 25 13 5.5 3.0 M M M M M
36000 -54.2 -65.6 280 33 17 5.5 3.0 M M M M M
34000 -50.0 -58.0 285 38 20 7.0 3.8 M M M M M
32000 -45.9 -50.6 280 36 18 7.0 3.8 M M M M M
30000 -41.3 -42.3 280 32 17 8.3 4.6 33.7 92.7 5.7 M M
29000 -38.8 -37.8 280 30 15 8.3 4.6 33.1 91.6 5.3 M M
28000 -36.3 -33.3 280 28 14 8.3 4.6 32.6 90.7 5.0 M M
27000 -33.9 -29.0 280 26 13 8.0 4.4 32.1 89.7 4.6 M M
26000 -31.5 -24.7 280 25 13 8.0 4.4 31.3 88.4 4.1 M M
25000 -29.1 -20.4 280 23 12 8.0 4.4 30.7 87.2 3.6 M M
24000 -26.7 -16.1 280 22 11 8.1 4.4 30.1 86.2 3.2 M M
23000 -24.2 -11.6 280 22 11 8.1 4.4 29.4 85.0 2.7 M M
22000 -21.8 -7.2 285 22 11 8.1 4.5 28.9 84.0 2.2 M M
21000 -19.4 -2.9 285 23 12 8.4 4.6 28.4 83.0 1.8 M M
20000 -16.9 1.6 285 23 12 8.4 4.6 27.8 82.1 1.4 M M
19500 -15.6 3.9 285 24 12 8.4 4.6 27.6 81.6 1.2 M M
19000 -14.3 6.3 290 24 12 8.4 4.6 27.4 81.3 1.0 M M
18500 -13.1 8.4 290 25 13 8.0 4.4 27.1 80.8 0.8 M M
18000 -11.9 10.6 290 25 13 8.0 4.4 26.8 80.3 0.5 M M
17500 -10.7 12.7 290 25 13 7.9 4.3 26.5 79.8 0.2 M M
17000 -9.6 14.7 290 24 13 7.7 4.2 26.2 79.1 -0.1 1097 5.6
16500 -7.9 17.8 290 24 13 7.6 4.2 25.7 78.2 -0.6 1024 5.2
16000 -6.8 19.8 290 24 12 7.5 4.1 25.3 77.5 -1.0 977 5.0
15500 -5.7 21.7 290 24 12 7.5 4.1 24.9 76.8 -1.4 929 4.7
15000 -4.6 23.7 290 24 12 7.7 4.2 24.5 76.1 -1.7 881 4.5
14500 -3.5 25.7 290 23 12 7.6 4.2 24.2 75.5 -2.1 832 4.2
14000 -2.3 27.9 290 22 11 8.2 4.5 23.9 75.0 -2.4 783 4.0
13500 -1.1 30.0 290 21 11 8.1 4.4 23.6 74.5 -2.7 732 3.7
13000 0.1 32.2 290 20 10 8.8 4.8 23.4 74.1 -2.9 681 3.5
12500 1.4 34.5 290 18 10 8.8 4.8 23.2 73.8 -3.1 627 3.2
12000 2.7 36.9 290 17 9 9.2 5.0 23.1 73.6 -3.3 573 2.9
11500 4.1 39.4 290 17 9 9.3 5.1 23.0 73.4 -3.4 517 2.6
11000 5.4 41.7 290 16 8 7.5 4.1 22.9 73.2 -3.6 464 2.4
10500 6.4 43.5 290 17 9 5.9 3.2 22.4 72.4 -4.0 417 2.1
10250 6.9 44.4 290 17 9 11.8 6.5 22.2 72.0 -4.2 394 2.0
10000 8.0 46.4 290 16 8 13.0 7.1 22.6 72.8 -3.9 354 1.8
9750 8.7 47.7 290 15 8 7.6 4.2 22.6 72.6 -4.0 327 1.7
9500 9.3 48.7 290 14 7 9.9 5.4 22.5 72.5 -4.1 300 1.5
9250 10.0 50.0 290 13 7 6.2 3.4 22.4 72.4 -4.1 273 1.4
9000 10.4 50.7 290 13 7 6.7 3.7 22.1 71.7 -4.5 254 1.3
8750 11.1 52.0 290 13 6 10.0 5.5 22.0 71.7 -4.6 226 1.1
8500 11.8 53.2 290 12 6 9.6 5.3 22.0 71.6 -4.6 197 1.0
8250 12.5 54.5 290 12 6 7.9 4.3 22.0 71.6 -4.7 169 0.9
8000 12.9 55.2 290 12 6 5.8 3.2 21.7 71.1 -5.0 148 0.8
7750 13.4 56.1 290 12 6 6.8 3.7 21.5 70.6 -5.2 127 0.6
7500 13.9 57.0 290 11 6 7.0 3.8 21.2 70.2 -5.5 105 0.5
7250 14.3 57.7 290 11 6 4.2 2.3 21.0 69.7 -5.8 85 0.4
7000 14.5 58.1 290 11 6 2.0 1.1 20.4 68.7 -6.4 72 0.4
6750 14.6 58.3 295 10 5 2.4 1.3 19.8 67.7 -7.0 60 0.3
6500 14.7 58.5 290 10 5 -1.1 -0.6 19.2 66.5 -7.7 51 0.3
6250 14.3 57.7 290 9 4 -6.4 -3.5 18.1 64.6 -8.8 54 0.3
6000 13.8 56.8 280 7 4 -6.9 -3.8 16.9 62.3 -10.1 63 0.3
5750 13.2 55.8 265 6 3 -9.0 -4.9 15.6 60.0 -11.4 73 0.4
5500 12.1 53.8 245 6 3 -20.5 -11.2 13.8 56.8 -13.3 99 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/14/2024 at 0900 MDT | 05/14/2024 at 1200 MDT
|
CAPE... +273.7 LI... +0.1 | CAPE... +434.3 LI... -1.7
CINH... -112.4 K Index... +21.3 | CINH... -10.3 K Index... +24.0
|
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 -55.5 -67.9 255 22 11 2.3 1.3 | -56.1 -69.0 250 22 11 2.2 1.2
45000 -52.7 -62.9 260 21 11 -2.6 -1.4 | -53.3 -63.9 240 24 12 -2.0 -1.1
40000 -56.4 -69.5 265 25 13 -2.5 -1.4 | -56.1 -69.0 250 30 16 -1.7 -0.9
38000 -55.8 -68.4 270 31 16 3.0 1.7 | -55.4 -67.7 255 35 18 2.3 1.3
36000 -53.8 -64.8 270 40 20 3.0 1.6 | -54.0 -65.2 260 41 21 2.3 1.3
34000 -50.9 -59.6 270 43 22 7.4 4.1 | -51.5 -60.7 265 44 23 7.5 4.1
32000 -46.4 -51.5 270 39 20 7.4 4.1 | -47.0 -52.6 260 40 21 7.5 4.1
30000 -41.8 -43.2 270 35 18 8.1 4.4 | -42.4 -44.3 260 36 19 8.3 4.6
29000 -39.4 -38.9 265 32 17 8.1 4.4 | -39.9 -39.8 260 34 17 8.3 4.6
28000 -37.0 -34.6 265 30 15 8.1 4.4 | -36.8 -34.2 260 31 16 8.3 4.6
27000 -34.5 -30.1 265 28 14 8.4 4.6 | -34.3 -29.7 260 29 15 8.5 4.7
26000 -32.0 -25.6 265 27 14 8.3 4.6 | -31.7 -25.1 260 29 15 8.5 4.7
25000 -29.5 -21.1 265 27 14 8.3 4.6 | -29.2 -20.6 260 28 14 8.5 4.7
24000 -27.0 -16.6 270 26 13 8.3 4.6 | -26.7 -16.1 260 27 14 8.5 4.6
23000 -24.5 -12.1 270 26 13 8.3 4.6 | -24.1 -11.4 265 27 14 8.5 4.6
22000 -22.1 -7.8 270 25 13 8.3 4.6 | -21.6 -6.9 270 27 14 8.4 4.6
21000 -19.6 -3.3 275 25 13 8.0 4.4 | -19.3 -2.7 275 27 14 7.1 3.9
20000 -17.2 1.0 275 26 13 8.1 4.4 | -17.2 1.0 275 27 14 7.2 3.9
19500 -16.0 3.2 280 26 13 8.1 4.4 | -16.1 3.0 280 27 14 7.2 3.9
19000 -14.8 5.4 280 26 13 8.1 4.5 | -15.0 5.0 280 27 14 7.2 3.9
18500 -13.0 8.6 280 26 13 7.7 4.2 | -14.0 6.8 280 27 14 7.7 4.2
18000 -11.9 10.6 280 27 14 7.8 4.3 | -12.9 8.8 280 27 14 7.6 4.2
17500 -10.8 12.6 280 27 14 7.5 4.1 | -11.7 10.9 280 28 14 8.0 4.4
17000 -9.7 14.5 280 27 14 7.5 4.1 | -10.5 13.1 280 28 14 8.2 4.5
16500 -8.6 16.5 280 27 14 7.5 4.1 | -9.3 15.3 280 28 14 8.2 4.5
16000 -7.5 18.5 280 27 14 7.5 4.1 | -8.2 17.2 280 28 14 8.0 4.4
15500 -6.4 20.5 280 27 14 7.6 4.2 | -7.0 19.4 280 28 14 8.0 4.4
15000 -5.3 22.5 280 27 14 7.9 4.3 | -5.8 21.6 280 27 14 8.6 4.7
14500 -4.1 24.6 280 26 13 7.9 4.3 | -4.5 23.9 280 26 14 8.6 4.7
14000 -2.9 26.8 280 25 13 8.6 4.7 | -2.6 27.3 280 25 13 9.1 5.0
13500 -1.7 28.9 280 24 12 8.6 4.7 | -1.3 29.7 280 24 12 9.1 5.0
13000 -0.4 31.3 275 23 12 8.7 4.8 | -0.0 32.0 280 23 12 9.0 5.0
12500 0.9 33.6 275 21 11 8.7 4.8 | 1.3 34.3 280 22 11 9.1 5.0
12000 2.2 36.0 275 20 10 8.5 4.7 | 2.6 36.7 280 20 10 9.1 5.0
11500 3.4 38.1 275 18 9 8.5 4.7 | 4.0 39.2 280 19 10 9.3 5.1
11000 4.6 40.3 275 17 9 7.4 4.0 | 5.2 41.4 280 17 9 6.8 3.7
10500 5.7 42.3 275 15 8 6.1 3.3 | 6.2 43.2 280 15 8 5.2 2.9
10250 6.2 43.2 275 15 8 11.1 6.1 | 6.7 44.1 280 14 7 12.4 6.8
10000 7.3 45.1 275 13 7 12.3 6.8 | 7.9 46.2 285 13 7 13.9 7.6
9750 7.9 46.2 275 12 6 7.9 4.3 | 8.5 47.3 285 12 6 7.5 4.1
9500 8.6 47.5 275 12 6 9.7 5.3 | 9.2 48.6 285 11 6 10.0 5.5
9250 9.3 48.7 270 11 6 6.7 3.7 | 9.9 49.8 285 11 5 6.6 3.6
9000 9.7 49.5 275 11 6 7.3 4.0 | 10.3 50.5 290 9 5 8.1 4.4
8750 10.4 50.7 275 10 5 10.1 5.6 | 11.1 52.0 290 9 5 11.7 6.4
8500 11.1 52.0 275 10 5 9.8 5.4 | 12.0 53.6 290 9 5 11.5 6.3
8250 11.8 53.2 275 9 5 8.3 4.6 | 12.8 55.0 290 9 5 8.6 4.7
8000 12.4 54.3 275 9 5 7.0 3.9 | 13.3 55.9 290 8 4 7.9 4.3
7750 12.9 55.2 270 9 4 8.4 4.6 | 14.1 57.4 295 8 4 11.5 6.3
7500 13.6 56.5 270 9 4 8.5 4.7 | 14.9 58.8 295 8 4 11.1 6.1
7250 14.1 57.4 270 8 4 6.2 3.4 | 15.6 60.1 295 8 4 8.3 4.5
7000 14.5 58.1 270 8 4 4.5 2.5 | 16.2 61.2 295 7 4 7.3 4.0
6750 14.8 58.6 265 8 4 4.9 2.7 | 16.9 62.4 295 7 4 12.2 6.7
6500 15.1 59.2 265 8 4 3.8 2.1 | 17.9 64.2 295 7 4 12.6 6.9
6250 15.3 59.5 255 7 4 2.7 1.5 | 18.7 65.7 300 7 4 9.6 5.3
6000 15.4 59.7 245 6 3 1.9 1.0 | 19.4 66.9 300 7 3 9.2 5.0
5750 15.6 60.1 230 6 3 5.2 2.8 | 20.1 68.2 300 6 3 11.4 6.3
5500 16.2 61.2 225 5 3 14.4 7.9 | 21.2 70.2 300 6 3 20.7 11.3
05/14/2024 at 1500 MDT | 05/14/2024 at 1800 MDT
|
CAPE... +434.5 LI... -1.7 | CAPE... +255.8 LI... -1.4
CINH... -13.1 K Index... +26.2 | CINH... -90.6 K Index... +25.8
|
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 -56.2 -69.2 245 21 11 2.2 1.2 | -55.9 -68.6 245 17 9 1.9 1.0
45000 -53.5 -64.3 235 25 13 -3.6 -2.0 | -53.7 -64.7 240 20 10 -4.9 -2.7
40000 -58.8 -73.8 245 34 17 -3.1 -1.7 | -60.7 -77.3 235 38 19 -4.1 -2.2
38000 -57.0 -70.6 250 36 18 5.0 2.7 | -58.5 -73.3 235 41 21 6.5 3.6
36000 -54.0 -65.2 250 38 20 5.0 2.7 | -54.5 -66.1 230 43 22 6.5 3.6
34000 -50.3 -58.5 255 39 20 7.8 4.3 | -50.1 -58.2 230 43 22 8.6 4.7
32000 -45.7 -50.3 255 37 19 7.8 4.3 | -45.0 -49.0 235 39 20 8.6 4.7
30000 -40.9 -41.6 255 34 18 8.2 4.5 | -39.9 -39.8 235 36 19 8.4 4.6
29000 -38.4 -37.1 255 33 17 8.2 4.5 | -37.4 -35.3 235 36 18 8.4 4.6
28000 -36.0 -32.8 255 31 16 8.2 4.5 | -34.3 -29.7 240 35 18 8.4 4.6
27000 -33.5 -28.3 255 30 16 8.3 4.5 | -31.9 -25.4 240 34 18 7.4 4.0
26000 -30.4 -22.7 255 29 15 8.3 4.5 | -29.7 -21.5 245 34 18 7.4 4.1
25000 -28.0 -18.4 255 28 15 8.3 4.5 | -27.5 -17.5 245 34 17 7.4 4.1
24000 -25.5 -13.9 255 28 14 7.8 4.3 | -25.3 -13.5 250 33 17 7.5 4.1
23000 -23.2 -9.8 255 27 14 7.8 4.3 | -23.1 -9.6 255 32 16 7.5 4.1
22000 -20.9 -5.6 260 27 14 7.8 4.3 | -20.9 -5.6 265 31 16 7.5 4.1
21000 -18.6 -1.5 260 26 14 7.7 4.2 | -18.7 -1.7 270 30 16 7.3 4.0
20000 -16.4 2.5 265 26 13 7.7 4.2 | -16.6 2.1 275 30 15 7.3 4.0
19500 -15.2 4.6 265 26 13 7.7 4.2 | -15.5 4.1 275 29 15 7.3 4.0
19000 -14.1 6.6 265 25 13 7.7 4.2 | -14.5 5.9 280 29 15 7.3 4.0
18500 -12.9 8.8 270 25 13 8.3 4.5 | -13.3 8.1 280 28 14 8.1 4.4
18000 -11.7 10.9 270 25 13 8.2 4.5 | -12.2 10.0 280 27 14 8.0 4.4
17500 -10.5 13.1 270 25 13 8.0 4.4 | -11.0 12.2 285 26 13 8.0 4.4
17000 -9.4 15.1 270 24 12 7.9 4.3 | -9.8 14.4 285 25 13 8.0 4.4
16500 -8.2 17.2 275 24 12 8.0 4.4 | -8.7 16.3 285 24 12 8.0 4.4
16000 -7.1 19.2 275 23 12 8.3 4.6 | -7.5 18.5 290 22 12 8.2 4.5
15500 -5.9 21.4 275 22 11 8.3 4.5 | -6.3 20.7 290 21 11 8.2 4.5
15000 -4.6 23.7 275 21 11 8.5 4.7 | -5.1 22.8 295 20 10 8.2 4.5
14500 -3.4 25.9 275 20 10 8.5 4.7 | -3.3 26.1 295 18 9 8.2 4.5
14000 -2.1 28.2 275 18 9 8.7 4.8 | -2.0 28.4 300 17 9 8.7 4.8
13500 -0.8 30.6 275 17 9 8.8 4.8 | -0.7 30.7 305 16 8 8.7 4.8
13000 0.5 32.9 275 16 8 8.9 4.9 | 0.5 32.9 305 15 8 8.5 4.7
12500 1.8 35.2 280 15 7 8.9 4.9 | 1.8 35.2 310 14 7 8.5 4.7
12000 3.1 37.6 280 13 7 8.8 4.8 | 3.0 37.4 310 13 6 8.2 4.5
11500 5.0 41.0 280 12 6 8.9 4.9 | 4.2 39.6 310 11 6 8.1 4.5
11000 6.2 43.2 280 10 5 6.9 3.8 | 5.4 41.7 310 9 5 7.5 4.1
10500 7.2 45.0 285 9 5 5.4 2.9 | 6.5 43.7 305 8 4 6.6 3.6
10250 7.7 45.9 285 8 4 12.2 6.7 | 7.0 44.6 305 7 4 10.1 5.5
10000 8.9 48.0 295 8 4 13.7 7.5 | 7.9 46.2 305 6 3 10.7 5.9
9750 9.5 49.1 295 8 4 7.5 4.1 | 8.5 47.3 305 6 3 7.5 4.1
9500 10.2 50.4 300 8 4 10.2 5.6 | 9.1 48.4 300 5 3 8.8 4.8
9250 10.9 51.6 305 8 4 5.5 3.0 | 9.7 49.5 300 4 2 6.9 3.8
9000 11.2 52.2 305 8 4 7.3 4.0 | 10.2 50.4 295 4 2 7.1 3.9
8750 12.0 53.6 305 8 4 12.3 6.7 | 10.8 51.4 290 4 2 8.8 4.8
8500 12.9 55.2 310 8 4 12.1 6.6 | 11.4 52.5 290 3 2 8.6 4.7
8250 13.7 56.7 310 9 4 7.7 4.2 | 12.0 53.6 285 3 1 7.7 4.2
8000 14.1 57.4 310 9 4 6.9 3.8 | 12.6 54.7 280 3 1 7.3 4.0
7750 14.9 58.8 310 9 5 12.4 6.8 | 13.1 55.6 270 2 1 8.5 4.6
7500 15.8 60.4 310 9 5 12.0 6.6 | 13.8 56.8 260 2 1 8.8 4.8
7250 16.6 61.9 310 9 5 8.4 4.6 | 14.4 57.9 240 2 1 7.9 4.3
7000 17.1 62.8 310 10 5 7.1 3.9 | 14.9 58.8 225 2 1 7.2 3.9
6750 17.8 64.0 310 10 5 12.4 6.8 | 15.4 59.7 210 2 1 8.1 4.4
6500 18.8 65.8 315 10 5 12.5 6.9 | 16.0 60.8 185 2 1 8.3 4.5
6250 19.6 67.3 315 10 5 8.9 4.9 | 16.6 61.9 175 3 1 7.7 4.2
6000 20.2 68.4 315 10 5 8.1 4.4 | 17.1 62.8 170 3 2 7.6 4.2
5750 20.9 69.6 315 10 5 12.3 6.8 | 17.7 63.9 165 4 2 7.1 3.9
5500 22.2 72.0 315 8 4 21.3 11.7 | 18.2 64.8 165 4 2 7.8 4.3
________________________________________________________________________________
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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