Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
924
UXUS97 KPUB 131242
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0642 MDT Saturday, July 13, 2024
This forecast is for the Air Force Academy for Saturday, July 13, 2024:
If the trigger temperature of 82.1 F/27.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 2395 ft/min (12.2 m/s)
Maximum height of thermals.................. 30688 ft MSL (23080 ft AGL)
Forecast maximum temperature................... 98.0 F/37.1 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................. 25715 ft MSL (18107 ft AGL)
Thermal soaring outlook for Sunday 07/14....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:45:17 / 20:25:03 MDT
Total possible sunshine........... 14 hr 39 min 46 sec (879 min 46 sec)
Altitude of sun at 13:05:10 MDT... 72.65 degrees
Upper air data from numerical model forecast valid on 07/13/2024 at 0600 MDT
Freezing level.................. 17207 ft MSL (9599 ft AGL)
Convective condensation level... 20354 ft MSL (12746 ft AGL)
Lifted condensation level....... 23268 ft MSL (15660 ft AGL)
Lifted index.................... -6.0
K index......................... +21.3
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 -60.8 -77.4 280 6 3 1.6 0.9 M M M M M
45000 -57.0 -70.6 300 9 5 4.0 2.2 M M M M M
40000 -50.9 -59.6 320 20 10 4.4 2.4 M M M M M
38000 -48.3 -54.9 315 20 10 4.4 2.4 M M M M M
36000 -45.7 -50.3 310 21 11 5.0 2.7 M M M M M
34000 -40.7 -41.3 310 22 11 7.6 4.2 M M M M M
32000 -36.2 -33.2 315 23 12 8.0 4.4 M M M M M
30000 -31.4 -24.5 325 16 8 7.9 4.3 36.2 97.1 -0.4 2320 11.8
29000 -29.1 -20.4 330 13 7 7.9 4.4 35.6 96.0 -0.9 2220 11.3
28000 -26.7 -16.1 340 11 6 7.7 4.2 34.9 94.8 -1.5 2121 10.8
27000 -24.4 -11.9 345 11 6 7.7 4.2 34.1 93.3 -2.2 2022 10.3
26000 -22.1 -7.8 350 12 6 7.7 4.2 33.3 92.0 -2.8 1924 9.8
25000 -19.8 -3.6 350 13 6 7.7 4.2 32.7 90.9 -3.4 1825 9.3
24000 -17.5 0.5 335 13 7 7.7 4.2 31.9 89.4 -4.1 1726 8.8
23000 -15.2 4.6 325 15 8 7.7 4.2 31.2 88.2 -4.7 1626 8.3
22000 -12.9 8.8 315 16 8 8.2 4.5 30.6 87.1 -5.3 1527 7.8
21000 -10.4 13.3 310 14 7 8.3 4.6 30.0 86.0 -6.0 1425 7.2
20000 -7.4 18.7 300 11 6 8.4 4.6 29.5 85.0 -6.6 1298 6.6
19500 -6.2 20.8 300 10 5 9.5 5.2 29.3 84.8 -6.8 1245 6.3
19000 -4.8 23.4 300 9 5 9.5 5.2 29.3 84.7 -7.0 1189 6.0
18500 -3.4 25.9 300 8 4 9.5 5.2 29.3 84.7 -7.1 1132 5.8
18000 -2.0 28.4 300 7 4 9.4 5.1 29.2 84.6 -7.2 1076 5.5
17500 -0.6 30.9 300 6 3 9.4 5.2 29.1 84.5 -7.3 1020 5.2
17000 0.7 33.3 300 6 3 9.3 5.1 29.1 84.4 -7.4 964 4.9
16500 2.1 35.8 300 5 3 9.3 5.1 29.0 84.2 -7.6 908 4.6
16000 3.5 38.3 300 5 3 9.6 5.3 29.0 84.1 -7.7 852 4.3
15500 5.0 41.0 300 5 3 9.9 5.4 29.0 84.1 -7.7 794 4.0
15000 6.4 43.5 300 5 3 9.9 5.5 29.0 84.2 -7.7 735 3.7
14500 7.8 46.0 300 5 3 9.3 5.1 29.0 84.2 -7.8 678 3.4
14000 9.2 48.6 305 5 3 9.4 5.2 28.9 84.0 -7.9 621 3.2
13500 10.6 51.1 305 5 3 8.6 4.7 28.8 83.9 -8.1 566 2.9
13000 11.8 53.2 315 6 3 9.3 5.1 28.6 83.5 -8.3 513 2.6
12500 13.3 55.9 320 7 3 9.9 5.5 28.7 83.6 -8.3 454 2.3
12000 14.8 58.6 325 8 4 10.1 5.5 28.7 83.6 -8.4 396 2.0
11750 15.5 59.9 325 8 4 8.8 4.8 28.7 83.7 -8.4 366 1.9
11500 16.1 61.0 325 9 5 8.2 4.5 28.6 83.4 -8.5 341 1.7
11250 16.8 62.2 325 9 5 9.0 4.9 28.5 83.3 -8.6 314 1.6
11000 17.4 63.3 325 10 5 8.8 4.8 28.4 83.1 -8.7 287 1.5
10750 18.1 64.6 325 11 5 8.7 4.8 28.3 83.0 -8.8 260 1.3
10500 18.7 65.7 325 11 6 9.2 5.1 28.3 82.9 -8.9 233 1.2
10250 19.4 66.9 325 12 6 8.6 4.7 28.2 82.8 -9.0 205 1.0
10000 20.0 68.0 325 12 6 8.0 4.4 28.1 82.6 -9.1 180 0.9
9750 20.6 69.1 325 12 6 7.3 4.0 28.0 82.3 -9.3 155 0.8
9500 21.2 70.2 320 13 7 10.7 5.9 27.8 82.1 -9.4 130 0.7
9250 22.0 71.6 320 13 7 9.1 5.0 28.0 82.4 -9.4 97 0.5
9000 22.4 72.3 320 13 7 4.1 2.2 27.6 81.8 -9.7 78 0.4
8750 22.8 73.0 325 13 7 5.2 2.8 27.3 81.1 -10.1 60 0.3
8500 23.2 73.8 325 13 7 4.5 2.5 26.9 80.4 -10.5 41 0.2
8250 23.4 74.1 325 14 7 1.5 0.8 26.4 79.6 -11.0 27 0.1
8000 23.3 73.9 320 14 7 -5.3 -2.9 25.6 78.0 -11.9 23 0.1
7750 22.2 72.0 315 13 7 -28.9 -15.8 23.7 74.7 -13.7 49 0.2
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 * * * * * *
07/13/2024 at 0900 MDT | 07/13/2024 at 1200 MDT
|
CAPE... +449.7 LI... +0.4 | CAPE... +155.3 LI... +0.5
CINH... -40.1 K Index... +15.9 | CINH... -18.3 K Index... +13.9
|
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 -60.4 -76.7 245 7 4 1.7 0.9 | -61.6 -78.9 260 11 6 0.7 0.4
45000 -56.3 -69.3 270 11 6 4.6 2.5 | -57.5 -71.5 275 13 7 5.9 3.3
40000 -49.7 -57.5 315 18 9 3.3 1.8 | -49.1 -56.4 320 10 5 3.7 2.0
38000 -47.8 -54.0 315 20 10 3.3 1.8 | -46.9 -52.4 325 14 7 3.7 2.0
36000 -45.5 -49.9 315 22 11 6.4 3.5 | -44.3 -47.7 325 18 9 6.1 3.4
34000 -40.9 -41.6 315 23 12 7.5 4.1 | -40.3 -40.5 325 22 11 6.7 3.7
32000 -36.4 -33.5 315 23 12 7.8 4.3 | -36.3 -33.3 325 26 13 7.4 4.1
30000 -32.0 -25.6 315 19 10 7.5 4.1 | -31.7 -25.1 320 22 11 7.7 4.2
29000 -29.7 -21.5 310 18 9 7.5 4.1 | -29.4 -20.9 320 20 11 7.7 4.2
28000 -27.5 -17.5 310 16 8 7.4 4.0 | -27.1 -16.8 315 19 10 7.8 4.3
27000 -25.3 -13.5 315 14 7 7.4 4.0 | -24.8 -12.6 310 18 9 7.8 4.3
26000 -23.1 -9.6 325 12 6 7.4 4.1 | -22.5 -8.5 305 17 9 7.8 4.3
25000 -20.9 -5.6 330 11 6 8.1 4.5 | -20.2 -4.4 300 16 8 7.9 4.3
24000 -18.4 -1.1 325 11 6 8.4 4.6 | -17.9 -0.2 300 14 7 7.9 4.4
23000 -15.9 3.4 320 12 6 8.4 4.6 | -15.5 4.1 300 13 7 8.0 4.4
22000 -13.3 8.1 315 12 6 8.9 4.9 | -12.5 9.5 295 12 6 8.8 4.9
21000 -10.0 14.0 305 10 5 8.9 4.9 | -9.8 14.4 290 11 6 8.8 4.8
20000 -7.4 18.7 295 9 5 8.9 4.9 | -7.2 19.0 285 11 6 8.8 4.9
19500 -6.1 21.0 290 8 4 9.1 5.0 | -5.9 21.4 285 11 6 8.6 4.7
19000 -4.7 23.5 290 7 4 9.1 5.0 | -4.6 23.7 285 10 5 8.6 4.7
18500 -3.4 25.9 295 6 3 9.1 5.0 | -3.3 26.1 285 9 5 8.8 4.8
18000 -2.1 28.2 295 5 3 9.2 5.0 | -2.0 28.4 285 8 4 9.0 4.9
17500 -0.7 30.7 300 5 2 9.2 5.0 | -0.7 30.7 290 7 3 9.0 5.0
17000 0.6 33.1 310 4 2 9.6 5.3 | 0.7 33.3 295 6 3 9.0 4.9
16500 2.0 35.6 320 4 2 9.6 5.3 | 2.0 35.6 305 6 3 9.0 5.0
16000 3.4 38.1 330 4 2 9.6 5.3 | 3.3 37.9 320 6 3 9.1 5.0
15500 4.9 40.8 340 5 2 9.6 5.3 | 4.7 40.5 330 8 4 9.2 5.1
15000 6.3 43.3 350 6 3 9.6 5.2 | 6.1 43.0 335 9 5 9.2 5.0
14500 7.7 45.9 350 7 3 9.3 5.1 | 7.4 45.3 345 11 5 8.8 4.8
14000 9.1 48.4 355 8 4 9.4 5.1 | 8.7 47.7 350 13 6 8.8 4.8
13500 10.4 50.7 355 9 5 8.7 4.8 | 10.0 50.0 355 14 7 9.4 5.2
13000 11.7 53.1 355 11 6 9.6 5.2 | 11.4 52.5 355 14 7 10.4 5.7
12500 13.2 55.8 355 12 6 9.2 5.0 | 13.0 55.4 355 14 7 10.4 5.7
12000 14.6 58.3 355 13 7 8.8 4.8 | 14.5 58.1 360 14 7 10.5 5.7
11750 15.2 59.4 355 14 7 8.9 4.9 | 15.3 59.5 360 14 7 8.8 4.8
11500 15.9 60.6 350 14 7 8.8 4.8 | 15.9 60.6 360 14 7 8.8 4.8
11250 16.5 61.7 350 15 8 8.6 4.7 | 16.7 62.1 360 14 7 10.5 5.7
11000 17.2 63.0 350 16 8 8.6 4.7 | 17.4 63.3 360 14 7 9.8 5.4
10750 17.8 64.0 350 16 8 8.9 4.9 | 18.2 64.8 360 14 7 10.8 5.9
10500 18.6 65.5 350 17 9 10.6 5.8 | 19.0 66.2 360 14 7 12.0 6.6
10250 19.3 66.7 350 18 9 9.1 5.0 | 19.9 67.8 360 14 7 10.0 5.5
10000 19.9 67.8 350 18 9 7.2 3.9 | 20.5 68.9 360 14 7 8.7 4.8
9750 20.4 68.7 350 18 9 7.5 4.1 | 21.2 70.2 360 14 7 8.6 4.7
9500 21.0 69.8 350 19 10 8.7 4.8 | 21.9 71.4 360 14 7 11.9 6.5
9250 21.7 71.1 350 19 10 8.5 4.6 | 22.8 73.0 360 14 7 11.9 6.5
9000 22.2 72.0 350 19 10 7.0 3.9 | 23.5 74.3 360 14 7 8.7 4.8
8750 22.6 72.7 350 19 10 7.3 4.0 | 24.3 75.7 360 14 7 9.4 5.2
8500 23.2 73.8 345 19 10 9.2 5.0 | 25.0 77.0 360 14 7 10.3 5.7
8250 23.9 75.0 345 17 9 11.0 6.0 | 25.8 78.4 360 14 7 11.7 6.4
8000 24.7 76.5 340 16 8 8.8 4.8 | 26.6 79.9 360 14 7 8.6 4.7
7750 25.3 77.5 340 14 7 12.3 6.7 | 27.3 81.1 360 13 7 15.3 8.4
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
07/13/2024 at 1500 MDT | 07/13/2024 at 1800 MDT
|
CAPE... +136.7 LI... -0.2 | CAPE... +130.2 LI... -0.8
CINH... -5.4 K Index... +18.0 | CINH... -3.1 K Index... +21.1
|
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 -61.6 -78.9 270 15 8 0.6 0.3 | -61.1 -78.0 295 13 6 1.4 0.7
45000 -58.1 -72.6 275 17 9 5.2 2.8 | -57.7 -71.9 300 17 9 3.9 2.2
40000 -50.4 -58.7 265 10 5 5.2 2.9 | -51.4 -60.5 290 19 10 5.5 3.0
38000 -46.9 -52.4 285 13 7 5.2 2.9 | -47.7 -53.9 295 25 13 5.5 3.0
36000 -43.7 -46.7 295 16 8 6.7 3.7 | -44.2 -47.6 295 31 16 7.9 4.3
34000 -39.5 -39.1 300 21 11 6.9 3.8 | -39.4 -38.9 295 30 16 8.1 4.4
32000 -35.3 -31.5 300 27 14 7.6 4.2 | -34.6 -30.3 295 30 15 8.2 4.5
30000 -30.8 -23.4 305 24 12 7.6 4.1 | -29.9 -21.8 300 28 15 7.7 4.2
29000 -28.6 -19.5 305 23 12 7.6 4.1 | -27.6 -17.7 305 27 14 7.7 4.2
28000 -26.3 -15.3 310 22 11 7.1 3.9 | -25.5 -13.9 305 26 13 5.9 3.2
27000 -24.2 -11.6 310 21 11 7.1 3.9 | -23.8 -10.8 310 24 12 6.0 3.3
26000 -22.1 -7.8 310 19 10 7.1 3.9 | -22.0 -7.6 310 22 11 6.0 3.3
25000 -19.9 -3.8 310 18 9 8.1 4.5 | -20.1 -4.2 315 20 10 7.8 4.3
24000 -17.4 0.7 310 18 9 8.4 4.6 | -17.7 0.1 315 16 8 8.3 4.5
23000 -14.9 5.2 305 18 9 8.4 4.6 | -15.3 4.5 325 13 7 8.3 4.6
22000 -11.8 10.8 305 17 9 8.4 4.6 | -12.9 8.8 335 10 5 8.7 4.8
21000 -9.3 15.3 310 16 8 8.5 4.6 | -9.6 14.7 360 8 4 8.8 4.8
20000 -6.9 19.6 315 14 7 8.5 4.6 | -7.0 19.4 030 9 4 8.7 4.8
19500 -5.6 21.9 320 13 7 8.7 4.8 | -5.7 21.7 035 9 5 9.4 5.2
19000 -4.3 24.3 330 11 6 8.7 4.8 | -4.3 24.3 035 9 5 9.4 5.2
18500 -3.0 26.6 340 10 5 8.8 4.8 | -2.9 26.8 040 10 5 9.5 5.2
18000 -1.7 28.9 350 10 5 9.0 5.0 | -1.5 29.3 040 10 5 9.8 5.4
17500 -0.4 31.3 355 10 5 9.0 4.9 | -0.0 32.0 040 10 5 9.8 5.4
17000 1.0 33.8 005 10 5 9.4 5.2 | 1.4 34.5 040 10 5 9.7 5.3
16500 2.4 36.3 010 10 5 9.4 5.2 | 2.9 37.2 040 11 5 9.7 5.3
16000 3.7 38.7 015 11 6 9.6 5.3 | 4.3 39.7 040 11 6 9.6 5.3
15500 5.2 41.4 015 11 6 9.8 5.4 | 5.8 42.4 040 11 6 9.5 5.2
15000 6.7 44.1 015 11 6 9.8 5.4 | 7.2 45.0 040 11 6 9.6 5.3
14500 8.1 46.6 020 11 6 9.9 5.4 | 8.6 47.5 040 11 6 9.9 5.4
14000 9.6 49.3 020 11 6 10.0 5.5 | 10.1 50.2 040 11 6 10.0 5.5
13500 11.0 51.8 020 11 6 8.9 4.9 | 11.5 52.7 040 11 6 8.6 4.7
13000 12.3 54.1 020 11 6 10.1 5.5 | 12.8 55.0 035 11 6 10.0 5.5
12500 14.0 57.2 020 11 6 10.7 5.9 | 14.5 58.1 035 12 6 10.4 5.7
12000 15.6 60.1 020 11 6 11.0 6.0 | 16.0 60.8 035 12 6 10.5 5.8
11750 16.4 61.5 020 11 6 8.9 4.9 | 16.8 62.2 035 12 6 9.5 5.2
11500 17.0 62.6 020 12 6 8.6 4.7 | 17.4 63.3 035 12 6 9.1 5.0
11250 17.7 63.9 020 12 6 10.5 5.8 | 18.2 64.8 030 12 6 10.0 5.5
11000 18.5 65.3 020 12 6 9.9 5.4 | 18.9 66.0 030 12 6 9.5 5.2
10750 19.2 66.6 020 12 6 10.4 5.7 | 19.6 67.3 030 12 6 10.6 5.8
10500 20.1 68.2 020 12 6 11.8 6.5 | 20.5 68.9 030 12 6 11.7 6.4
10250 20.9 69.6 020 12 6 10.4 5.7 | 21.3 70.3 030 12 6 9.8 5.4
10000 21.6 70.9 020 12 6 8.9 4.9 | 22.0 71.6 030 12 6 8.6 4.7
9750 22.3 72.1 020 12 6 8.7 4.8 | 22.6 72.7 030 12 6 8.7 4.8
9500 23.0 73.4 020 12 6 11.2 6.2 | 23.3 73.9 030 12 6 9.9 5.4
9250 23.9 75.0 020 12 6 11.5 6.3 | 24.1 75.4 030 12 6 10.5 5.8
9000 24.6 76.3 020 12 6 9.1 5.0 | 24.8 76.6 030 12 6 9.8 5.4
8750 25.3 77.5 020 12 6 9.5 5.2 | 25.6 78.1 030 12 6 10.0 5.5
8500 26.1 79.0 020 12 6 10.5 5.8 | 26.3 79.3 025 12 6 10.1 5.6
8250 26.9 80.4 020 11 6 12.1 6.6 | 27.1 80.8 025 12 6 10.5 5.8
8000 27.7 81.9 020 11 6 8.8 4.8 | 27.8 82.0 025 12 6 9.3 5.1
7750 28.5 83.3 020 11 6 14.9 8.1 | 28.5 83.3 025 11 6 11.7 6.4
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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