Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
733
UXUS97 KPUB 051205
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0605 MDT Wednesday, June 5, 2024
This forecast is for the Air Force Academy for Wednesday, June 5, 2024:
If the trigger temperature of 68.8 F/20.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1136 ft/min (5.8 m/s)
Maximum height of thermals.................. 20679 ft MSL (13080 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 0845 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................. 17857 ft MSL (10258 ft AGL)
Thermal soaring outlook for Thursday 06/06..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:34:01 / 20:21:53 MDT
Total possible sunshine........... 14 hr 47 min 52 sec (887 min 52 sec)
Altitude of sun at 12:57:57 MDT... 73.67 degrees
Upper air data from numerical model forecast valid on 06/05/2024 at 0600 MDT
Freezing level.................. 16076 ft MSL (8477 ft AGL)
Convective condensation level... 19444 ft MSL (11845 ft AGL)
Lifted condensation level....... 20287 ft MSL (12688 ft AGL)
Lifted index.................... -0.8
K index......................... -5.8
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 -62.4 -80.3 360 16 8 1.4 0.7 M M M M M
45000 -59.3 -74.7 335 25 13 3.9 2.2 M M M M M
40000 -52.4 -62.3 340 35 18 7.0 3.9 M M M M M
38000 -48.2 -54.8 340 38 19 7.1 3.9 M M M M M
36000 -44.0 -47.2 340 40 21 7.1 3.9 M M M M M
34000 -39.0 -38.2 335 37 19 8.3 4.6 M M M M M
32000 -34.0 -29.2 335 33 17 8.3 4.6 M M M M M
30000 -29.1 -20.4 330 27 14 8.2 4.5 39.9 103.9 6.9 M M
29000 -26.6 -15.9 330 24 13 8.2 4.5 39.4 102.9 6.5 M M
28000 -24.2 -11.6 330 22 11 8.1 4.4 38.9 102.1 6.2 M M
27000 -21.8 -7.2 325 22 11 7.9 4.3 38.1 100.6 5.6 M M
26000 -19.4 -2.9 325 23 12 7.9 4.3 37.4 99.4 5.1 M M
25000 -17.1 1.2 325 23 12 8.1 4.4 36.8 98.3 4.7 M M
24000 -15.1 4.8 325 25 13 6.1 3.3 35.7 96.2 3.8 M M
23000 -12.8 9.0 325 28 15 6.1 3.3 34.0 93.2 2.4 M M
22000 -11.0 12.2 325 31 16 6.2 3.4 32.8 91.1 1.4 M M
21000 -9.1 15.6 325 30 16 6.3 3.4 31.5 88.8 0.3 M M
20000 -7.2 19.0 325 30 16 6.3 3.4 30.3 86.6 -0.8 1070 5.4
19500 -6.3 20.7 325 30 15 6.3 3.5 29.8 85.6 -1.3 1027 5.2
19000 -5.4 22.3 325 29 15 6.1 3.4 29.2 84.6 -1.8 984 5.0
18500 -4.4 24.1 320 28 14 6.2 3.4 28.6 83.5 -2.3 942 4.8
18000 -3.5 25.7 320 27 14 6.2 3.4 28.0 82.4 -2.9 899 4.6
17500 -2.6 27.3 315 25 13 6.2 3.4 27.4 81.3 -3.5 856 4.4
17000 -1.7 28.9 310 23 12 6.2 3.4 26.8 80.3 -4.0 814 4.1
16500 -0.7 30.7 305 22 11 6.2 3.4 26.2 79.2 -4.6 771 3.9
16000 0.2 32.4 300 21 11 6.2 3.4 25.6 78.2 -5.2 729 3.7
15500 1.1 34.0 295 20 10 6.4 3.5 25.1 77.1 -5.7 687 3.5
15000 2.0 35.6 290 19 10 6.6 3.6 24.5 76.2 -6.3 644 3.3
14500 3.0 37.4 290 18 9 6.6 3.6 24.0 75.3 -6.8 601 3.1
14000 3.9 39.0 290 16 8 6.5 3.6 23.5 74.3 -7.4 558 2.8
13500 4.9 40.8 295 15 7 6.5 3.6 23.0 73.4 -8.0 515 2.6
13000 5.8 42.4 300 13 7 6.8 3.7 22.5 72.5 -8.5 472 2.4
12500 6.7 44.1 300 12 6 6.7 3.7 22.0 71.7 -9.1 429 2.2
12000 7.7 45.9 305 12 6 6.5 3.6 21.5 70.8 -9.7 386 2.0
11750 8.1 46.6 305 11 6 6.5 3.6 21.3 70.3 -10.0 365 1.9
11500 8.6 47.5 310 11 6 7.1 3.9 21.0 69.9 -10.3 343 1.7
11250 9.1 48.4 310 11 6 6.7 3.7 20.8 69.5 -10.5 321 1.6
11000 9.5 49.1 310 11 6 5.9 3.2 20.5 69.0 -10.9 301 1.5
10750 9.9 49.8 310 11 5 6.1 3.3 20.3 68.5 -11.2 281 1.4
10500 10.3 50.5 310 10 5 5.9 3.3 20.0 67.9 -11.6 261 1.3
10250 10.7 51.3 305 10 5 6.6 3.6 19.7 67.4 -12.0 243 1.2
10000 11.2 52.2 305 10 5 7.3 4.0 19.5 67.1 -12.3 221 1.1
9750 11.7 53.1 305 10 5 7.2 3.9 19.3 66.7 -12.5 198 1.0
9500 12.2 54.0 300 10 5 7.4 4.1 19.1 66.4 -12.8 176 0.9
9250 12.7 54.9 300 9 5 6.7 3.7 18.9 66.0 -13.0 153 0.8
9000 13.2 55.8 300 8 4 6.3 3.4 18.6 65.5 -13.3 131 0.7
8750 13.7 56.7 300 7 4 6.7 3.7 18.4 65.1 -13.6 109 0.6
8500 14.2 57.6 300 6 3 6.8 3.7 18.2 64.7 -13.9 87 0.4
8250 14.6 58.3 295 6 3 2.7 1.5 17.9 64.1 -14.2 67 0.3
8000 14.2 57.6 295 6 3 -16.1 -8.9 16.7 62.1 -15.3 70 0.4
7750 12.2 54.0 280 6 3 -37.0 -20.3 13.9 57.0 -18.2 126 0.6
7500 M M M M M M M M M M M M
7250 M M M M M M M M M M M M
7000 M M M M M M M M M M M M
6750 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/05/2024 at 0900 MDT | 06/05/2024 at 1200 MDT
|
CAPE... 0.0 LI... +3.4 | CAPE... 0.0 LI... +3.0
CINH... 0.0 K Index... -5.9 | CINH... 0.0 K Index... -6.2
|
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 -62.1 -79.8 360 8 4 1.7 1.0 | -62.1 -79.8 320 6 3 1.2 0.7
45000 -58.4 -73.1 325 19 10 3.7 2.0 | -59.0 -74.2 310 19 10 3.7 2.0
40000 -52.4 -62.3 330 29 15 6.7 3.7 | -52.7 -62.9 325 31 16 7.7 4.2
38000 -48.3 -54.9 335 34 17 6.8 3.7 | -48.1 -54.6 330 34 17 7.7 4.3
36000 -44.2 -47.6 335 39 20 6.6 3.6 | -42.9 -45.2 330 37 19 7.7 4.3
34000 -38.7 -37.7 335 35 18 8.5 4.6 | -38.2 -36.8 325 33 17 7.8 4.3
32000 -33.6 -28.5 335 31 16 8.7 4.8 | -33.6 -28.5 320 30 15 7.9 4.4
30000 -28.8 -19.8 335 30 15 8.0 4.4 | -28.7 -19.7 320 29 15 8.2 4.5
29000 -26.4 -15.5 335 30 15 8.0 4.4 | -26.2 -15.2 320 28 15 8.2 4.5
28000 -24.0 -11.2 335 29 15 7.6 4.1 | -23.8 -10.8 320 28 14 7.4 4.0
27000 -21.8 -7.2 330 30 15 7.4 4.1 | -21.6 -6.9 320 28 14 7.1 3.9
26000 -19.6 -3.3 330 30 15 7.4 4.1 | -19.5 -3.1 320 28 14 7.1 3.9
25000 -17.4 0.7 325 30 16 7.4 4.1 | -17.4 0.7 320 28 14 7.1 3.9
24000 -15.3 4.5 325 31 16 6.6 3.6 | -15.3 4.5 315 29 15 6.9 3.8
23000 -13.4 7.9 320 31 16 6.6 3.6 | -13.3 8.1 315 30 15 6.9 3.8
22000 -11.4 11.5 320 31 16 6.6 3.6 | -11.2 11.8 315 31 16 6.9 3.8
21000 -9.4 15.1 320 30 15 6.7 3.7 | -8.6 16.5 315 30 16 6.7 3.7
20000 -7.4 18.7 320 28 14 6.7 3.7 | -6.6 20.1 315 29 15 6.7 3.7
19500 -5.9 21.4 320 26 13 6.8 3.7 | -5.6 21.9 315 29 15 6.7 3.7
19000 -4.9 23.2 320 25 13 7.1 3.9 | -4.6 23.7 315 28 14 6.2 3.4
18500 -3.8 25.2 320 24 12 7.1 3.9 | -3.7 25.3 315 26 14 6.2 3.4
18000 -2.8 27.0 320 23 12 6.9 3.8 | -2.8 27.0 315 25 13 6.3 3.5
17500 -1.8 28.8 320 22 11 6.8 3.7 | -1.9 28.6 315 23 12 6.3 3.5
17000 -0.8 30.6 315 21 11 6.8 3.7 | -0.9 30.4 315 22 11 6.3 3.5
16500 0.2 32.4 315 19 10 6.3 3.5 | -0.0 32.0 310 20 10 5.9 3.2
16000 1.2 34.2 310 18 9 6.4 3.5 | 0.8 33.4 310 19 10 6.0 3.3
15500 2.1 35.8 305 17 9 6.0 3.3 | 1.7 35.1 305 18 9 5.3 2.9
15000 2.9 37.2 300 16 8 5.9 3.3 | 2.4 36.3 305 17 9 5.3 2.9
14500 3.8 38.8 290 15 8 5.2 2.9 | 3.1 37.6 300 17 9 4.8 2.6
14000 4.4 39.9 290 13 7 4.5 2.5 | 3.6 38.5 300 15 8 4.4 2.4
13500 5.0 41.0 285 12 6 4.5 2.5 | 4.2 39.6 300 14 7 5.0 2.8
13000 5.6 42.1 285 9 4 4.7 2.6 | 4.9 40.8 305 9 5 6.9 3.8
12500 6.3 43.3 285 6 3 5.3 2.9 | 5.9 42.6 320 7 4 8.6 4.7
12000 7.0 44.6 300 4 2 5.5 3.0 | 7.3 45.1 325 6 3 9.6 5.3
11750 7.4 45.3 315 3 2 5.8 3.2 | 8.0 46.4 330 6 3 9.8 5.4
11500 7.9 46.2 330 3 2 8.6 4.7 | 8.7 47.7 330 6 3 10.7 5.9
11250 8.6 47.5 345 3 2 8.1 4.5 | 9.5 49.1 335 6 3 9.5 5.2
11000 9.0 48.2 350 4 2 6.2 3.4 | 10.2 50.4 335 5 3 8.7 4.7
10750 9.5 49.1 350 4 2 6.5 3.5 | 10.8 51.4 335 5 3 7.8 4.3
10500 9.9 49.8 350 5 3 7.4 4.1 | 11.5 52.7 335 5 3 12.0 6.6
10250 10.5 50.9 350 6 3 7.9 4.3 | 12.5 54.5 335 5 3 12.8 7.0
10000 11.0 51.8 345 6 3 7.1 3.9 | 13.2 55.8 340 5 3 9.0 4.9
9750 11.5 52.7 340 7 4 7.4 4.1 | 14.0 57.2 340 5 3 10.3 5.6
9500 12.0 53.6 335 7 4 6.8 3.8 | 14.7 58.5 340 5 3 8.9 4.9
9250 12.5 54.5 335 8 4 6.9 3.8 | 15.3 59.5 340 5 3 8.9 4.9
9000 13.0 55.4 330 7 4 8.5 4.7 | 16.1 61.0 345 5 3 10.9 6.0
8750 13.7 56.7 320 7 4 9.2 5.0 | 16.9 62.4 345 5 3 11.4 6.3
8500 14.3 57.7 310 6 3 8.9 4.9 | 17.7 63.9 345 5 3 10.8 5.9
8250 14.9 58.8 305 6 3 9.1 5.0 | 18.5 65.3 350 5 3 10.5 5.8
8000 15.7 60.3 305 6 3 14.4 7.9 | 19.5 67.1 350 5 2 17.9 9.8
7750 17.1 62.8 305 6 3 22.2 12.2 | 21.3 70.3 350 5 2 29.3 16.1
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
06/05/2024 at 1500 MDT | 06/05/2024 at 1800 MDT
|
CAPE... 0.0 LI... +2.9 | CAPE... +0.9 LI... +2.0
CINH... 0.0 K Index... +2.3 | CINH... -0.3 K Index... +15.3
|
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 -62.7 -80.9 280 7 4 1.1 0.6 | -63.4 -82.1 275 12 6 0.8 0.4
45000 -59.5 -75.1 305 21 11 4.1 2.2 | -60.2 -76.4 300 22 12 4.8 2.6
40000 -52.6 -62.7 315 26 14 8.4 4.6 | -52.3 -62.1 315 31 16 8.2 4.5
38000 -47.5 -53.5 320 29 15 8.4 4.6 | -47.3 -53.1 315 31 16 8.2 4.5
36000 -41.8 -43.2 325 32 16 7.8 4.3 | -41.8 -43.2 315 31 16 7.9 4.3
34000 -37.5 -35.5 320 30 15 7.2 4.0 | -37.2 -35.0 315 29 15 7.6 4.2
32000 -33.1 -27.6 315 28 14 7.5 4.1 | -32.6 -26.7 310 27 14 7.8 4.3
30000 -28.4 -19.1 310 28 15 8.0 4.4 | -28.3 -18.9 310 29 15 7.2 4.0
29000 -26.0 -14.8 310 29 15 8.0 4.4 | -26.2 -15.2 310 30 16 7.2 4.0
28000 -23.6 -10.5 305 29 15 7.3 4.0 | -24.0 -11.2 310 31 16 7.3 4.0
27000 -21.5 -6.7 305 29 15 7.1 3.9 | -21.8 -7.2 310 32 17 7.3 4.0
26000 -19.4 -2.9 310 30 15 7.2 3.9 | -19.7 -3.5 315 33 17 7.3 4.0
25000 -17.3 0.9 310 30 15 7.2 4.0 | -17.5 0.5 315 34 17 7.4 4.1
24000 -15.1 4.8 310 31 16 7.5 4.1 | -15.3 4.5 315 34 17 7.6 4.2
23000 -12.8 9.0 310 32 16 7.5 4.1 | -13.0 8.6 315 33 17 7.6 4.2
22000 -10.6 12.9 310 33 17 7.4 4.0 | -10.8 12.6 315 33 17 7.5 4.1
21000 -8.0 17.6 310 33 17 6.9 3.8 | -8.1 17.4 315 32 16 6.9 3.8
20000 -5.9 21.4 310 34 17 6.9 3.8 | -6.0 21.2 315 31 16 6.9 3.8
19500 -4.8 23.4 315 34 17 6.7 3.7 | -5.0 23.0 315 31 16 6.5 3.6
19000 -3.9 25.0 315 34 17 5.7 3.1 | -4.2 24.4 310 30 15 5.3 2.9
18500 -3.1 26.4 310 33 17 5.8 3.2 | -3.4 25.9 310 29 15 5.3 2.9
18000 -2.2 28.0 310 32 16 5.7 3.2 | -2.6 27.3 305 28 14 6.0 3.3
17500 -1.4 29.5 310 31 16 5.7 3.2 | -1.8 28.8 295 27 14 6.3 3.5
17000 -0.5 31.1 305 29 15 5.8 3.2 | -1.0 30.2 290 25 13 7.1 3.9
16500 0.3 32.5 300 28 14 5.9 3.2 | 0.2 32.4 285 24 12 9.2 5.0
16000 1.1 34.0 295 26 14 6.0 3.3 | 1.5 34.7 280 23 12 9.2 5.1
15500 1.9 35.4 295 25 13 6.6 3.6 | 2.8 37.0 280 21 11 8.3 4.6
15000 2.8 37.0 290 23 12 6.8 3.8 | 4.0 39.2 280 20 10 8.4 4.6
14500 3.7 38.7 290 20 10 7.4 4.1 | 5.2 41.4 275 18 9 8.0 4.4
14000 4.8 40.6 295 16 8 7.7 4.2 | 6.4 43.5 275 15 8 7.8 4.3
13500 5.9 42.6 300 13 7 8.2 4.5 | 7.5 45.5 280 12 6 7.4 4.0
13000 7.2 45.0 305 9 5 9.5 5.2 | 8.5 47.3 285 7 4 6.9 3.8
12500 8.6 47.5 315 8 4 9.0 5.0 | 9.6 49.3 290 5 2 7.9 4.4
12000 9.9 49.8 320 7 4 9.7 5.3 | 10.8 51.4 320 3 2 8.4 4.6
11750 10.7 51.3 325 7 3 9.8 5.4 | 11.5 52.7 340 3 1 8.9 4.9
11500 11.4 52.5 330 7 3 10.3 5.6 | 12.2 54.0 360 3 2 10.0 5.5
11250 12.2 54.0 330 7 3 9.4 5.2 | 12.9 55.2 015 4 2 9.2 5.1
11000 12.8 55.0 335 6 3 9.0 4.9 | 13.6 56.5 020 4 2 8.8 4.8
10750 13.5 56.3 335 6 3 8.3 4.6 | 14.2 57.6 025 4 2 8.1 4.4
10500 14.2 57.6 335 6 3 11.5 6.3 | 14.9 58.8 025 4 2 11.3 6.2
10250 15.1 59.2 340 6 3 12.1 6.7 | 15.8 60.4 030 5 2 12.0 6.6
10000 15.9 60.6 340 6 3 9.2 5.1 | 16.6 61.9 030 5 3 9.2 5.0
9750 16.6 61.9 340 6 3 10.3 5.6 | 17.3 63.1 030 5 3 10.1 5.6
9500 17.4 63.3 345 6 3 9.0 5.0 | 18.0 64.4 030 5 3 9.0 5.0
9250 18.0 64.4 345 6 3 9.0 4.9 | 18.7 65.7 030 5 3 9.0 4.9
9000 18.8 65.8 345 6 3 10.6 5.8 | 19.4 66.9 030 5 3 10.3 5.7
8750 19.6 67.3 345 6 3 10.9 6.0 | 20.2 68.4 035 5 3 10.5 5.8
8500 20.4 68.7 350 6 3 10.6 5.8 | 20.9 69.6 035 6 3 10.3 5.6
8250 21.2 70.2 350 6 3 12.0 6.6 | 21.7 71.1 035 6 3 10.1 5.5
8000 22.2 72.0 350 6 3 18.4 10.1 | 22.5 72.5 035 6 3 13.1 7.2
7750 23.9 75.0 355 6 3 25.2 13.8 | 23.6 74.5 035 6 3 18.0 9.9
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 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 Air Force Academy
in Colorado Springs, Colorado at
North Latitude: 38 deg 58 min 48.000 sec
West Longitude: 104 deg 49 min 12.000 sec
Elevation: 6572 feet (2003 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.
CIN (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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