Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
715
UXUS97 KBOU 120109
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1908 MDT Thursday, July 11, 2024
This forecast is for Friday, July 12, 2024:
If the trigger temperature of 90.3 F/32.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1763 ft/min (9.0 m/s)
Maximum height of thermals.................. 23086 ft MSL (17804 ft AGL)
Forecast maximum temperature................... 101.0 F/38.8 C
Time of trigger temperature.................... 1030 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................. 19358 ft MSL (14076 ft AGL)
Thermal soaring outlook for Saturday 07/13..... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 40430 ft MSL (35148 ft AGL)
Wave soaring outlook for Saturday 07/13........ Poor
Remarks... Very hot this weekend
Sunrise/Sunset.................... 05:42:27 / 20:28:03 MDT
Total possible sunshine........... 14 hr 45 min 35 sec (885 min 35 sec)
Altitude of sun at 13:05:15 MDT... 72.01 degrees
Upper air data from numerical model forecast valid on 07/12/2024 at 0600 MDT
Freezing level.................. 16790 ft MSL (11508 ft AGL)
Convective condensation level... 18655 ft MSL (13373 ft AGL)
Lifted condensation level....... 20169 ft MSL (14886 ft AGL)
Lifted index.................... -3.5
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 -60.4 -76.7 330 12 6 2.9 1.6 M M M M M
45000 -56.5 -69.7 330 20 10 2.1 1.2 M M M M M
40000 -52.5 -62.5 330 33 17 5.1 2.8 M M M M M
38000 -49.5 -57.1 330 34 17 5.1 2.8 M M M M M
36000 -46.4 -51.5 335 35 18 5.7 3.1 M M M M M
34000 -41.5 -42.7 335 34 17 8.4 4.6 M M M M M
32000 -36.4 -33.5 340 33 17 8.5 4.6 M M M M M
30000 -31.7 -25.1 340 30 16 7.8 4.3 43.7 110.7 4.1 M M
29000 -28.8 -19.8 340 29 15 7.8 4.3 42.8 109.1 3.5 M M
28000 -26.4 -15.5 340 27 14 8.5 4.7 42.2 108.0 3.0 M M
27000 -23.9 -11.0 340 26 14 8.4 4.6 41.6 106.9 2.6 M M
26000 -21.4 -6.5 345 26 13 8.4 4.6 41.1 106.1 2.2 M M
25000 -18.9 -2.0 345 25 13 7.1 3.9 40.7 105.3 1.9 M M
24000 -17.0 1.4 345 25 13 6.6 3.6 39.4 103.0 0.9 M M
23000 -15.0 5.0 340 25 13 6.6 3.6 38.3 101.0 -0.1 1754 8.9
22000 -13.0 8.6 340 25 13 7.4 4.0 37.3 99.2 -1.0 1665 8.5
21000 -10.9 12.4 340 25 13 7.6 4.2 36.5 97.6 -1.8 1570 8.0
20000 -8.7 16.3 335 24 13 7.8 4.3 35.8 96.4 -2.6 1475 7.5
19500 -7.6 18.3 335 24 12 8.2 4.5 35.5 95.8 -2.9 1428 7.3
19000 -6.3 20.7 335 22 12 9.0 5.0 35.3 95.6 -3.1 1374 7.0
18500 -5.0 23.0 330 20 10 9.0 4.9 35.2 95.3 -3.2 1319 6.7
18000 -3.6 25.5 330 19 10 9.3 5.1 35.1 95.2 -3.4 1264 6.4
17500 -2.2 28.0 330 17 9 9.4 5.1 35.0 95.0 -3.4 1207 6.1
17000 -0.8 30.6 335 16 8 9.4 5.1 35.0 94.9 -3.5 1151 5.8
16500 0.6 33.1 335 15 8 9.4 5.1 34.9 94.8 -3.6 1095 5.6
16000 1.9 35.4 335 14 7 9.3 5.1 34.8 94.7 -3.7 1038 5.3
15500 3.3 37.9 335 13 7 9.6 5.3 34.8 94.6 -3.8 982 5.0
15000 4.8 40.6 330 13 7 9.6 5.3 34.8 94.6 -3.9 924 4.7
14500 6.2 43.2 330 12 6 9.5 5.2 34.7 94.5 -3.9 867 4.4
14000 8.3 46.9 325 12 6 9.4 5.1 34.6 94.3 -4.1 783 4.0
13500 9.7 49.5 320 12 6 9.6 5.3 34.6 94.3 -4.1 726 3.7
13000 11.1 52.0 315 12 6 9.6 5.3 34.6 94.2 -4.2 668 3.4
12500 12.5 54.5 310 12 6 9.2 5.0 34.5 94.2 -4.3 612 3.1
12000 13.8 56.8 305 12 6 9.1 5.0 34.4 93.9 -4.4 557 2.8
11500 15.2 59.4 300 13 6 8.9 4.9 34.3 93.8 -4.5 502 2.5
11000 16.5 61.7 295 12 6 8.6 4.7 34.1 93.5 -4.7 448 2.3
10500 17.7 63.9 290 13 6 3.7 2.0 34.0 93.1 -4.9 396 2.0
10250 17.9 64.2 290 12 6 5.6 3.1 33.3 92.0 -5.5 384 2.0
10000 18.7 65.7 285 12 6 12.1 6.7 33.4 92.2 -5.5 353 1.8
9750 19.4 66.9 285 12 6 11.4 6.2 33.5 92.3 -5.4 322 1.6
9500 20.2 68.4 280 12 6 7.3 4.0 33.6 92.5 -5.4 291 1.5
9250 20.6 69.1 280 12 6 4.7 2.6 33.2 91.7 -5.8 274 1.4
9000 21.1 70.0 275 11 6 9.2 5.1 33.0 91.4 -6.0 250 1.3
8750 21.8 71.2 270 11 6 10.2 5.6 33.0 91.4 -6.0 221 1.1
8500 22.5 72.5 265 11 6 7.7 4.2 33.0 91.4 -6.1 193 1.0
8250 23.0 73.4 265 11 6 5.3 2.9 32.7 90.9 -6.4 172 0.9
8000 23.4 74.1 260 11 6 7.2 3.9 32.4 90.3 -6.7 152 0.8
7750 24.0 75.2 255 11 6 8.1 4.4 32.3 90.1 -6.8 127 0.6
7500 24.5 76.1 255 11 6 5.0 2.8 32.1 89.7 -7.1 104 0.5
7250 24.7 76.5 250 11 6 3.2 1.8 31.6 88.9 -7.6 89 0.5
7000 25.0 77.0 250 11 6 4.1 2.2 31.1 88.0 -8.0 74 0.4
6750 25.2 77.4 245 11 6 1.3 0.7 30.6 87.1 -8.6 60 0.3
6500 25.1 77.2 245 11 5 -2.5 -1.4 29.8 85.7 -9.4 56 0.3
6250 24.8 76.6 240 10 5 -5.2 -2.9 28.8 83.8 -10.5 57 0.3
6000 24.6 76.3 235 10 5 2.1 1.1 27.8 82.0 -11.5 58 0.3
5750 24.6 76.3 235 10 5 -9.2 -5.1 27.2 80.9 -12.2 49 0.2
5500 22.4 72.3 225 8 4 -48.3 -26.5 24.3 75.7 -15.2 108 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/12/2024 at 0900 MDT | 07/12/2024 at 1200 MDT
|
CAPE... +79.6 LI... +0.5 | CAPE... +56.4 LI... +0.4
CINH... -97.0 K Index... +15.7 | CINH... -7.8 K Index... +10.2
|
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 -60.3 -76.5 345 9 5 2.4 1.3 | -59.9 -75.8 320 5 3 1.7 0.9
45000 -56.5 -69.7 335 17 9 2.8 1.5 | -56.6 -69.9 330 17 9 2.9 1.6
40000 -51.8 -61.2 335 34 17 4.4 2.4 | -51.9 -61.4 340 33 17 4.5 2.5
38000 -49.1 -56.4 330 33 17 4.4 2.4 | -49.2 -56.6 335 31 16 4.5 2.5
36000 -46.5 -51.7 330 32 17 5.2 2.9 | -46.5 -51.7 330 30 15 5.2 2.8
34000 -41.6 -42.9 335 31 16 8.5 4.7 | -41.7 -43.1 330 28 14 8.3 4.5
32000 -36.4 -33.5 335 30 15 8.6 4.7 | -36.7 -34.1 330 26 13 8.3 4.5
30000 -31.8 -25.2 335 27 14 7.7 4.2 | -31.3 -24.3 330 23 12 8.0 4.4
29000 -28.9 -20.0 340 25 13 7.7 4.2 | -28.9 -20.0 330 22 11 8.0 4.4
28000 -26.6 -15.9 340 23 12 7.9 4.3 | -26.5 -15.7 335 21 11 7.9 4.3
27000 -24.3 -11.7 340 22 12 7.9 4.3 | -24.1 -11.4 335 20 10 7.9 4.4
26000 -21.9 -7.4 340 22 11 7.9 4.3 | -21.7 -7.1 335 20 10 7.9 4.4
25000 -19.5 -3.1 340 21 11 7.5 4.1 | -19.4 -2.9 335 19 10 7.6 4.1
24000 -17.3 0.9 340 22 11 7.4 4.1 | -17.1 1.2 335 19 10 7.4 4.1
23000 -15.1 4.8 335 23 12 7.4 4.1 | -14.9 5.2 335 20 10 7.4 4.1
22000 -12.9 8.8 330 24 13 7.3 4.0 | -12.7 9.1 330 20 10 7.4 4.1
21000 -10.8 12.6 325 24 12 7.4 4.0 | -10.5 13.1 325 20 10 7.5 4.1
20000 -8.6 16.5 320 23 12 7.6 4.1 | -8.3 17.1 320 19 10 7.6 4.2
19500 -7.6 18.3 320 23 12 8.2 4.5 | -7.2 19.0 320 19 10 8.1 4.4
19000 -6.3 20.7 315 22 11 9.3 5.1 | -5.9 21.4 320 18 9 8.9 4.9
18500 -4.9 23.2 315 21 11 9.3 5.1 | -4.6 23.7 315 18 9 8.9 4.9
18000 -3.5 25.7 315 19 10 9.4 5.2 | -3.3 26.1 315 17 9 9.3 5.1
17500 -2.1 28.2 315 18 9 9.4 5.2 | -1.9 28.6 315 16 8 9.3 5.1
17000 -0.8 30.6 315 17 9 9.4 5.2 | -0.5 31.1 315 16 8 9.3 5.1
16500 0.6 33.1 315 16 8 9.3 5.1 | 1.6 34.9 315 15 8 9.4 5.1
16000 2.0 35.6 315 15 8 9.3 5.1 | 3.0 37.4 315 14 7 9.3 5.1
15500 4.1 39.4 315 14 7 9.6 5.3 | 4.3 39.7 315 14 7 9.3 5.1
15000 5.5 41.9 315 13 7 9.6 5.3 | 5.7 42.3 320 14 7 9.3 5.1
14500 6.9 44.4 315 13 7 9.5 5.2 | 7.1 44.8 320 13 7 9.2 5.1
14000 8.3 46.9 315 13 6 9.5 5.2 | 8.5 47.3 320 13 7 9.2 5.1
13500 9.8 49.6 315 12 6 9.5 5.2 | 9.8 49.6 320 13 7 9.4 5.2
13000 11.2 52.2 315 12 6 9.5 5.2 | 11.2 52.2 320 13 7 9.4 5.2
12500 12.6 54.7 315 13 6 9.4 5.2 | 12.6 54.7 320 13 7 9.4 5.1
12000 14.0 57.2 315 13 7 9.4 5.2 | 14.0 57.2 320 13 7 9.4 5.1
11500 15.4 59.7 315 13 7 9.2 5.0 | 15.4 59.7 325 13 7 9.7 5.3
11000 16.7 62.1 315 13 7 9.0 5.0 | 16.8 62.2 325 13 7 9.9 5.5
10500 18.0 64.4 310 13 7 4.6 2.5 | 18.0 64.4 325 13 7 4.8 2.6
10250 18.3 64.9 310 13 7 7.2 3.9 | 18.4 65.1 325 13 7 8.3 4.5
10000 19.1 66.4 310 13 7 12.3 6.7 | 19.3 66.7 325 13 7 13.3 7.3
9750 19.9 67.8 310 13 7 11.6 6.3 | 20.2 68.4 325 13 6 12.4 6.8
9500 20.7 69.3 305 13 7 7.6 4.2 | 21.1 70.0 330 13 6 8.4 4.6
9250 21.1 70.0 305 13 7 6.0 3.3 | 21.6 70.9 325 13 6 7.7 4.2
9000 21.8 71.2 305 13 7 10.2 5.6 | 22.3 72.1 330 13 6 11.9 6.5
8750 22.5 72.5 305 13 7 10.5 5.8 | 23.2 73.8 330 12 6 11.7 6.4
8500 23.3 73.9 300 13 7 8.2 4.5 | 24.0 75.2 330 12 6 9.5 5.2
8250 23.7 74.7 300 13 7 5.9 3.2 | 24.6 76.3 330 12 6 7.4 4.0
8000 24.2 75.6 300 13 7 8.4 4.6 | 25.3 77.5 330 12 6 10.7 5.9
7750 25.0 77.0 295 13 7 9.5 5.2 | 26.2 79.2 330 12 6 12.3 6.7
7500 25.5 77.9 295 13 7 6.1 3.3 | 27.0 80.6 330 12 6 9.3 5.1
7250 25.9 78.6 295 13 7 4.2 2.3 | 27.6 81.7 330 12 6 7.5 4.1
7000 26.2 79.2 295 13 6 5.8 3.2 | 28.2 82.8 330 12 6 10.5 5.8
6750 26.7 80.1 290 12 6 6.8 3.8 | 29.2 84.6 330 12 6 13.0 7.2
6500 27.1 80.8 285 10 5 5.3 2.9 | 30.1 86.2 330 11 6 10.7 5.9
6250 27.4 81.3 280 9 5 5.1 2.8 | 30.8 87.4 330 11 6 9.8 5.4
6000 27.8 82.0 275 8 4 3.7 2.0 | 31.6 88.9 330 11 6 9.6 5.3
5750 28.0 82.4 265 6 3 8.6 4.7 | 32.4 90.3 335 11 5 17.0 9.3
5500 29.2 84.6 260 5 3 21.3 11.7 | 34.2 93.6 335 10 5 30.6 16.8
07/12/2024 at 1500 MDT | 07/12/2024 at 1800 MDT
|
CAPE... +31.1 LI... +0.7 | CAPE... +37.9 LI... +0.4
CINH... -14.8 K Index... +11.8 | CINH... -42.1 K Index... +15.9
|
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 -59.9 -75.8 275 7 4 2.1 1.2 | -60.9 -77.6 285 12 6 1.4 0.8
45000 -56.3 -69.3 315 16 8 2.6 1.4 | -57.0 -70.6 310 19 10 4.3 2.3
40000 -51.8 -61.2 340 28 15 4.8 2.7 | -50.7 -59.3 330 24 12 4.0 2.2
38000 -48.9 -56.0 330 28 14 4.8 2.6 | -48.3 -54.9 320 26 14 4.0 2.2
36000 -46.0 -50.8 320 28 14 5.6 3.1 | -45.9 -50.6 315 29 15 5.1 2.8
34000 -41.3 -42.3 320 26 13 8.0 4.4 | -41.3 -42.3 310 27 14 7.7 4.2
32000 -36.6 -33.9 320 24 13 8.1 4.5 | -36.7 -34.1 305 24 12 8.0 4.4
30000 -31.3 -24.3 320 22 12 7.8 4.3 | -31.0 -23.8 310 20 10 8.6 4.7
29000 -29.0 -20.2 320 21 11 7.8 4.3 | -28.4 -19.1 315 18 9 8.6 4.7
28000 -26.6 -15.9 320 21 11 7.7 4.2 | -25.9 -14.6 315 17 9 8.0 4.4
27000 -24.4 -11.9 325 20 10 7.7 4.2 | -23.6 -10.5 320 16 8 8.0 4.4
26000 -22.1 -7.8 325 19 10 7.7 4.2 | -21.2 -6.2 320 15 7 8.0 4.4
25000 -19.7 -3.5 330 18 9 8.3 4.5 | -18.8 -1.8 320 14 7 7.3 4.0
24000 -17.3 0.9 330 18 9 8.3 4.6 | -16.7 1.9 320 14 7 7.3 4.0
23000 -14.8 5.4 330 17 9 8.3 4.6 | -14.6 5.7 325 14 7 7.3 4.0
22000 -12.3 9.9 330 17 9 9.0 4.9 | -12.3 9.9 325 15 8 8.8 4.8
21000 -9.6 14.7 330 17 9 9.0 4.9 | -9.8 14.4 330 16 8 8.8 4.8
20000 -6.9 19.6 325 17 9 9.0 4.9 | -7.2 19.0 330 16 8 8.9 4.9
19500 -5.5 22.1 325 17 9 8.9 4.9 | -5.9 21.4 330 17 9 9.0 4.9
19000 -4.2 24.4 325 17 9 8.9 4.9 | -4.6 23.7 335 17 9 9.1 5.0
18500 -2.9 26.8 325 16 8 8.9 4.9 | -3.2 26.2 335 17 9 9.1 5.0
18000 -1.6 29.1 330 16 8 8.6 4.7 | -1.9 28.6 340 17 9 9.2 5.1
17500 -0.3 31.5 330 16 8 8.6 4.7 | -0.5 31.1 345 16 8 9.2 5.1
17000 0.9 33.6 335 16 8 8.8 4.8 | 0.9 33.6 345 16 8 9.3 5.1
16500 2.2 36.0 335 15 8 9.0 4.9 | 2.3 36.1 350 16 8 9.4 5.1
16000 3.6 38.5 335 15 8 9.0 4.9 | 3.7 38.7 350 16 8 9.4 5.1
15500 4.9 40.8 335 15 8 9.3 5.1 | 5.1 41.2 355 15 8 9.1 5.0
15000 6.3 43.3 340 14 7 9.3 5.1 | 6.5 43.7 355 15 8 9.1 5.0
14500 7.6 45.7 340 14 7 9.2 5.1 | 7.9 46.2 355 15 8 9.2 5.1
14000 9.0 48.2 340 13 7 9.2 5.1 | 9.2 48.6 360 14 7 9.2 5.1
13500 11.1 52.0 340 13 7 9.4 5.2 | 11.3 52.3 360 14 7 9.3 5.1
13000 12.5 54.5 345 13 7 9.4 5.2 | 12.7 54.9 360 13 7 9.2 5.1
12500 13.9 57.0 345 12 6 9.5 5.2 | 14.1 57.4 360 13 7 9.5 5.2
12000 15.3 59.5 345 12 6 9.5 5.2 | 15.5 59.9 360 13 6 9.6 5.3
11500 16.7 62.1 345 12 6 9.8 5.4 | 17.0 62.6 355 12 6 9.4 5.1
11000 18.2 64.8 345 12 6 10.3 5.7 | 18.4 65.1 355 12 6 9.6 5.2
10500 19.4 66.9 345 12 6 4.3 2.3 | 19.5 67.1 355 12 6 4.8 2.7
10250 19.8 67.6 345 12 6 9.4 5.1 | 20.0 68.0 355 12 6 8.9 4.9
10000 20.8 69.4 345 12 6 13.6 7.5 | 20.8 69.4 350 11 6 12.7 6.9
9750 21.7 71.1 345 12 6 12.4 6.8 | 21.7 71.1 350 11 6 11.9 6.5
9500 22.5 72.5 345 12 6 7.0 3.9 | 22.5 72.5 350 11 6 7.2 3.9
9250 22.9 73.2 345 12 6 7.2 3.9 | 22.9 73.2 350 11 6 7.1 3.9
9000 23.8 74.8 345 12 6 12.9 7.1 | 23.7 74.7 345 11 6 12.3 6.7
8750 24.7 76.5 345 12 6 12.1 6.6 | 24.6 76.3 345 11 6 11.8 6.5
8500 25.5 77.9 345 12 6 8.8 4.8 | 25.4 77.7 345 11 6 8.9 4.9
8250 26.0 78.8 345 12 6 6.2 3.4 | 25.9 78.6 340 11 6 6.4 3.5
8000 26.6 79.9 345 12 6 11.4 6.3 | 26.6 79.9 340 11 6 10.8 5.9
7750 27.7 81.9 350 11 6 13.6 7.4 | 27.5 81.5 340 11 5 12.8 7.0
7500 28.5 83.3 350 11 6 9.2 5.0 | 28.3 82.9 335 11 5 9.2 5.0
7250 29.1 84.4 350 11 6 7.1 3.9 | 28.9 84.0 335 11 5 7.2 3.9
7000 29.7 85.5 350 11 6 10.9 6.0 | 29.5 85.1 335 10 5 10.5 5.8
6750 30.7 87.3 350 11 6 13.3 7.3 | 30.5 86.9 335 10 5 12.6 6.9
6500 31.6 88.9 350 11 6 10.1 5.5 | 31.3 88.3 330 10 5 9.6 5.3
6250 32.3 90.1 350 11 5 8.9 4.9 | 31.9 89.4 330 10 5 7.9 4.3
6000 33.0 91.4 345 10 5 11.0 6.0 | 32.6 90.7 330 10 5 10.8 5.9
5750 34.0 93.2 345 10 5 18.4 10.1 | 33.6 92.5 330 9 5 14.2 7.8
5500 35.7 96.3 345 9 5 25.1 13.8 | 34.6 94.3 330 9 4 12.3 6.8
________________________________________________________________________________
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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