Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
530
UXUS97 KPUB 061212
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0612 MDT Sunday, April 6, 2025
This forecast is for the Air Force Academy for Sunday, April 6, 2025:
If the trigger temperature of 34.9 F/1.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 880 ft/min (4.5 m/s)
Maximum height of thermals.................. 18010 ft MSL (10409 ft AGL)
Forecast maximum temperature................... 50.0 F/10.5 C
Time of trigger temperature.................... 0900 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................. 15363 ft MSL (7762 ft AGL)
Thermal soaring outlook for Monday 04/07....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:35:09 / 19:27:54 MDT
Total possible sunshine........... 12 hr 52 min 45 sec (772 min 45 sec)
Altitude of sun at 13:01:31 MDT... 57.78 degrees
Upper air data from numerical model forecast valid on 04/06/2025 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 16724 ft MSL (9123 ft AGL)
Lifted condensation level....... 17416 ft MSL (9814 ft AGL)
Lifted index.................... +3.3
K index......................... -4.0
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 -55.4 -67.7 290 13 7 1.1 0.6 M M M M M
45000 -53.8 -64.8 305 14 7 1.2 0.6 M M M M M
40000 -54.5 -66.1 005 15 8 -0.6 -0.3 M M M M M
38000 -54.9 -66.8 025 23 12 -0.8 -0.4 M M M M M
36000 -55.4 -67.7 035 40 21 -0.8 -0.4 M M M M M
34000 -55.8 -68.4 040 58 30 3.4 1.9 M M M M M
32000 -51.6 -60.9 035 57 30 7.0 3.8 M M M M M
30000 -47.4 -53.3 035 57 29 7.5 4.1 22.1 71.8 9.3 M M
29000 -45.1 -49.2 035 54 28 7.5 4.1 21.1 70.0 8.6 M M
28000 -42.9 -45.2 030 51 26 7.5 4.1 20.3 68.5 8.0 M M
27000 -40.6 -41.1 030 49 25 7.6 4.2 19.5 67.1 7.6 M M
26000 -38.6 -37.5 030 45 23 6.3 3.4 18.3 65.0 6.7 M M
25000 -36.7 -34.1 025 40 20 6.3 3.4 17.0 62.6 5.7 M M
24000 -34.8 -30.6 020 35 18 6.3 3.4 15.8 60.4 4.8 M M
23000 -32.5 -26.5 015 32 16 6.2 3.4 14.2 57.5 3.5 M M
22000 -30.6 -23.1 010 30 15 6.2 3.4 12.9 55.2 2.4 M M
21000 -28.7 -19.7 005 28 15 7.4 4.1 11.8 53.2 1.5 M M
20000 -26.3 -15.3 005 27 14 8.2 4.5 11.2 52.1 1.0 M M
19500 -25.1 -13.2 360 26 13 8.2 4.5 10.9 51.6 0.7 M M
19000 -23.9 -11.0 360 25 13 8.2 4.5 10.7 51.2 0.5 M M
18500 -22.6 -8.7 355 24 12 7.9 4.3 10.4 50.8 0.3 M M
18000 -21.5 -6.7 355 24 13 7.6 4.2 10.1 50.1 -0.0 874 4.4
17500 -20.4 -4.7 355 25 13 7.6 4.2 9.7 49.5 -0.4 825 4.2
17000 -19.4 -2.9 355 25 13 5.9 3.3 9.2 48.5 -0.9 781 4.0
16500 -18.5 -1.3 355 25 13 6.2 3.4 8.6 47.4 -1.4 739 3.8
16000 -17.6 0.3 355 25 13 4.9 2.7 7.9 46.2 -2.0 699 3.5
15500 -16.9 1.6 355 25 13 4.8 2.6 7.1 44.7 -2.8 662 3.4
15000 -16.2 2.8 360 25 13 4.7 2.6 6.3 43.3 -3.6 626 3.2
14500 -15.5 4.1 360 24 12 4.8 2.6 5.4 41.8 -4.4 590 3.0
14000 -14.8 5.4 360 23 12 5.5 3.0 4.6 40.3 -5.1 554 2.8
13500 -13.8 7.2 005 21 11 6.4 3.5 4.1 39.3 -5.7 511 2.6
13000 -12.9 8.8 005 19 10 6.3 3.4 3.5 38.4 -6.2 467 2.4
12500 -12.0 10.4 010 19 10 5.9 3.2 3.0 37.3 -6.8 425 2.2
12000 -11.2 11.8 005 19 10 5.9 3.3 2.3 36.2 -7.5 386 2.0
11750 -10.7 12.7 005 19 10 6.5 3.6 2.0 35.7 -7.8 365 1.9
11500 -10.2 13.6 360 18 10 6.5 3.5 1.8 35.2 -8.1 343 1.7
11250 -9.7 14.5 360 18 9 7.4 4.1 1.5 34.8 -8.3 321 1.6
11000 -9.2 15.4 355 18 9 6.9 3.8 1.4 34.5 -8.5 297 1.5
10750 -8.7 16.3 355 17 9 6.0 3.3 1.1 34.0 -8.8 276 1.4
10500 -8.3 17.1 355 17 9 5.4 3.0 0.8 33.4 -9.2 256 1.3
10250 -7.8 18.0 350 17 9 8.3 4.5 0.5 32.9 -9.5 235 1.2
10000 -7.1 19.2 350 16 8 9.0 4.9 0.5 32.9 -9.5 206 1.0
9750 -6.6 20.1 350 15 8 6.5 3.6 0.3 32.5 -9.7 183 0.9
9500 -6.1 21.0 345 14 7 7.4 4.0 0.1 32.2 -10.0 159 0.8
9250 -5.5 22.1 345 13 7 6.4 3.5 -0.1 31.8 -10.2 136 0.7
9000 -5.0 23.0 340 12 6 7.4 4.1 -0.4 31.3 -10.5 114 0.6
8750 -4.4 24.1 330 11 6 8.9 4.9 -0.5 31.2 -10.6 88 0.4
8500 -3.8 25.2 325 10 5 8.9 4.9 -0.5 31.0 -10.7 61 0.3
8250 -3.1 26.4 315 9 5 7.5 4.1 -0.6 30.9 -10.9 35 0.2
8000 -3.0 26.6 315 8 4 -6.9 -3.8 -1.2 29.8 -11.5 24 0.1
7750 -4.3 24.3 300 7 3 -25.8 -14.1 -3.2 26.2 -13.6 56 0.3
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 * * * * * *
04/06/2025 at 0900 MDT | 04/06/2025 at 1200 MDT
|
CAPE... 0.0 LI... +4.3 | CAPE... 0.0 LI... +3.8
CINH... 0.0 K Index... -10.6 | CINH... 0.0 K Index... -3.4
|
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 -55.7 -68.3 285 13 6 1.2 0.7 | -55.6 -68.1 285 15 8 1.4 0.8
45000 -53.9 -65.0 330 13 7 1.4 0.7 | -53.4 -64.1 295 11 6 0.9 0.5
40000 -55.6 -68.1 005 20 10 -1.3 -0.7 | -56.5 -69.7 350 22 11 -2.2 -1.2
38000 -56.1 -69.0 015 26 14 -0.0 -0.0 | -57.1 -70.8 360 27 14 1.1 0.6
36000 -56.1 -69.0 020 38 19 -0.1 -0.0 | -56.4 -69.5 005 33 17 1.1 0.6
34000 -56.0 -68.8 025 49 25 5.5 3.0 | -55.7 -68.3 010 39 20 4.6 2.5
32000 -51.3 -60.3 025 47 24 7.8 4.3 | -50.4 -58.7 010 40 20 7.9 4.3
30000 -46.6 -51.9 025 45 23 8.3 4.6 | -45.7 -50.3 010 40 20 8.2 4.5
29000 -44.1 -47.4 025 44 23 8.2 4.5 | -43.3 -45.9 010 38 19 8.2 4.5
28000 -41.7 -43.1 025 42 22 8.2 4.5 | -40.8 -41.4 010 36 18 8.2 4.5
27000 -39.2 -38.6 025 41 21 8.3 4.6 | -38.4 -37.1 010 34 17 8.1 4.5
26000 -36.9 -34.4 020 39 20 7.3 4.0 | -36.2 -33.2 010 33 17 7.2 4.0
25000 -34.7 -30.5 020 37 19 7.3 4.0 | -34.0 -29.2 010 33 17 7.3 4.0
24000 -32.0 -25.6 015 34 17 7.0 3.9 | -31.8 -25.2 010 32 17 7.5 4.1
23000 -30.3 -22.5 015 33 17 5.2 2.8 | -30.2 -22.4 010 32 17 4.7 2.6
22000 -28.8 -19.8 010 32 17 5.2 2.9 | -28.8 -19.8 010 33 17 4.7 2.6
21000 -27.2 -17.0 005 32 16 5.6 3.1 | -27.3 -17.1 015 34 17 5.0 2.7
20000 -25.5 -13.9 005 31 16 5.8 3.2 | -25.2 -13.4 010 33 17 5.8 3.2
19500 -24.6 -12.3 005 30 16 5.8 3.2 | -24.4 -11.9 010 32 16 5.8 3.2
19000 -23.8 -10.8 005 30 15 5.9 3.2 | -23.5 -10.3 010 32 16 5.8 3.2
18500 -22.9 -9.2 005 30 15 7.0 3.8 | -22.6 -8.7 010 31 16 7.2 4.0
18000 -21.7 -7.1 005 29 15 7.9 4.3 | -21.5 -6.7 010 31 16 7.8 4.3
17500 -20.5 -4.9 005 28 15 8.0 4.4 | -20.3 -4.5 010 30 15 7.7 4.2
17000 -19.4 -2.9 005 28 14 7.0 3.8 | -19.2 -2.6 010 29 15 7.3 4.0
16500 -18.3 -0.9 360 27 14 7.1 3.9 | -18.1 -0.6 005 28 15 7.4 4.1
16000 -17.3 0.9 360 26 13 6.6 3.6 | -17.0 1.4 005 28 14 6.6 3.6
15500 -16.3 2.7 360 25 13 6.6 3.6 | -16.1 3.0 360 27 14 6.6 3.6
15000 -15.4 4.3 360 25 13 5.6 3.1 | -15.1 4.8 360 27 14 6.2 3.4
14500 -14.6 5.7 355 25 13 5.1 2.8 | -14.2 6.4 355 27 14 6.0 3.3
14000 -13.9 7.0 355 24 12 5.1 2.8 | -13.3 8.1 355 27 14 6.1 3.3
13500 -13.1 8.4 355 23 12 5.1 2.8 | -12.4 9.7 350 27 14 6.1 3.4
13000 -12.3 9.9 355 22 11 5.5 3.0 | -11.5 11.3 350 27 14 6.4 3.5
12500 -11.4 11.5 355 20 10 6.0 3.3 | -10.5 13.1 350 26 13 5.5 3.0
12000 -10.6 12.9 355 18 10 5.8 3.2 | -9.9 14.2 345 24 12 5.5 3.0
11750 -10.1 13.8 355 18 9 6.1 3.4 | -9.4 15.1 345 23 12 6.3 3.5
11500 -9.7 14.5 355 18 9 6.2 3.4 | -9.0 15.8 345 22 11 6.5 3.5
11250 -9.2 15.4 355 18 9 6.7 3.7 | -8.5 16.7 345 20 10 6.9 3.8
11000 -8.7 16.3 355 18 9 6.7 3.7 | -7.9 17.8 345 17 9 8.3 4.5
10750 -8.2 17.2 355 17 9 6.5 3.6 | -7.3 18.9 345 17 9 9.4 5.2
10500 -7.7 18.1 355 17 9 6.1 3.3 | -6.6 20.1 345 16 8 8.6 4.7
10250 -7.3 18.9 355 17 9 7.8 4.3 | -5.9 21.4 345 15 8 10.6 5.8
10000 -6.6 20.1 350 16 8 8.7 4.8 | -5.1 22.8 345 14 7 11.3 6.2
9750 -6.0 21.2 350 16 8 7.5 4.1 | -4.3 24.3 345 14 7 9.8 5.4
9500 -5.5 22.1 345 15 8 8.1 4.4 | -3.6 25.5 345 14 7 10.6 5.8
9250 -4.9 23.2 345 15 8 7.1 3.9 | -2.8 27.0 345 14 7 8.8 4.8
9000 -4.4 24.1 340 14 7 8.2 4.5 | -2.2 28.0 345 14 7 9.1 5.0
8750 -3.7 25.3 335 13 7 9.9 5.5 | -1.4 29.5 345 13 7 11.1 6.1
8500 -3.0 26.6 330 12 6 9.6 5.3 | -0.6 30.9 345 13 7 10.5 5.7
8250 -2.3 27.9 325 12 6 9.4 5.1 | 0.2 32.4 345 13 7 10.9 6.0
8000 -1.5 29.3 320 11 6 12.7 7.0 | 1.1 34.0 345 13 7 16.5 9.1
7750 -0.3 31.5 320 9 5 19.4 10.7 | 2.7 36.9 345 12 6 25.1 13.8
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
04/06/2025 at 1500 MDT | 04/06/2025 at 1800 MDT
|
CAPE... 0.0 LI... +2.5 | CAPE... +0.3 LI... +0.2
CINH... 0.0 K Index... -3.5 | CINH... -0.8 K Index... +12.3
|
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 -56.7 -70.1 280 16 8 1.0 0.5 | -57.1 -70.8 295 18 9 0.8 0.4
45000 -55.2 -67.4 300 18 9 1.2 0.7 | -55.9 -68.6 320 19 10 0.9 0.5
40000 -57.5 -71.5 335 27 14 -1.6 -0.9 | -57.1 -70.8 345 33 17 -0.8 -0.4
38000 -57.4 -71.3 345 31 16 2.3 1.3 | -56.6 -69.9 350 37 19 2.6 1.4
36000 -56.0 -68.8 345 34 17 2.3 1.3 | -55.1 -67.2 355 36 19 2.6 1.4
34000 -54.4 -65.9 350 36 19 6.6 3.6 | -53.4 -64.1 360 37 19 5.1 2.8
32000 -50.2 -58.4 350 36 19 7.0 3.9 | -50.2 -58.4 360 37 19 5.3 2.9
30000 -45.9 -50.6 350 36 18 8.3 4.6 | -46.8 -52.2 360 37 19 8.4 4.6
29000 -43.5 -46.3 355 35 18 8.1 4.5 | -44.3 -47.7 360 36 19 8.2 4.5
28000 -41.0 -41.8 355 35 18 8.1 4.5 | -41.9 -43.4 005 36 19 8.2 4.5
27000 -38.6 -37.5 355 34 18 8.2 4.5 | -39.4 -38.9 010 36 19 8.2 4.5
26000 -36.4 -33.5 355 33 17 7.2 3.9 | -37.1 -34.8 010 36 19 7.6 4.2
25000 -34.2 -29.6 360 33 17 7.2 3.9 | -34.8 -30.6 010 36 19 7.7 4.2
24000 -32.1 -25.8 360 33 17 7.4 4.0 | -32.5 -26.5 010 36 18 7.9 4.3
23000 -30.1 -22.2 005 32 16 4.5 2.5 | -30.4 -22.7 010 35 18 4.8 2.6
22000 -28.8 -19.8 005 31 16 4.5 2.5 | -29.0 -20.2 010 33 17 4.8 2.7
21000 -27.3 -17.1 005 31 16 6.1 3.3 | -27.5 -17.5 005 32 17 6.3 3.5
20000 -25.4 -13.7 005 30 16 6.6 3.6 | -25.6 -14.1 005 31 16 6.6 3.6
19500 -24.4 -11.9 005 30 15 6.6 3.6 | -24.6 -12.3 005 31 16 6.6 3.6
19000 -23.4 -10.1 005 30 15 6.6 3.6 | -23.6 -10.5 005 31 16 6.6 3.6
18500 -22.4 -8.3 005 29 15 7.3 4.0 | -22.6 -8.7 360 30 16 7.5 4.1
18000 -21.3 -6.3 005 29 15 7.6 4.2 | -21.4 -6.5 360 30 15 7.8 4.3
17500 -20.1 -4.2 360 28 15 7.7 4.2 | -20.2 -4.4 360 30 15 7.9 4.3
17000 -19.0 -2.2 360 28 14 8.1 4.4 | -19.0 -2.2 360 30 15 7.8 4.3
16500 -17.7 0.1 360 27 14 8.1 4.4 | -17.9 -0.2 360 30 15 7.8 4.3
16000 -16.6 2.1 355 27 14 7.5 4.1 | -16.7 1.9 355 30 15 7.8 4.3
15500 -15.4 4.3 355 27 14 7.6 4.1 | -15.5 4.1 355 30 16 7.8 4.3
15000 -14.3 6.3 355 27 14 7.2 3.9 | -14.4 6.1 350 30 16 8.1 4.5
14500 -13.3 8.1 350 28 14 7.0 3.9 | -13.2 8.2 350 30 15 8.2 4.5
14000 -12.2 10.0 350 28 14 7.2 4.0 | -11.9 10.6 345 30 15 9.0 4.9
13500 -11.1 12.0 350 28 14 7.4 4.1 | -10.5 13.1 340 28 15 9.4 5.2
13000 -10.0 14.0 345 28 14 7.6 4.2 | -9.1 15.6 340 27 14 9.8 5.4
12500 -8.8 16.2 345 27 14 7.7 4.2 | -7.8 18.0 340 27 14 8.0 4.4
12000 -7.7 18.1 345 27 14 7.4 4.1 | -6.7 19.9 340 27 14 7.6 4.2
11750 -7.2 19.0 345 26 13 6.7 3.7 | -6.1 21.0 340 26 14 8.0 4.4
11500 -6.7 19.9 345 25 13 7.3 4.0 | -5.5 22.1 340 26 13 7.8 4.3
11250 -6.0 21.2 345 24 12 9.3 5.1 | -5.0 23.0 345 26 13 7.7 4.2
11000 -5.4 22.3 345 23 12 8.3 4.5 | -4.4 24.1 345 26 13 6.8 3.7
10750 -4.8 23.4 345 21 11 7.0 3.8 | -3.9 25.0 345 25 13 6.2 3.4
10500 -4.3 24.3 345 19 10 6.5 3.6 | -3.5 25.7 345 25 13 5.6 3.1
10250 -3.8 25.2 345 17 9 9.8 5.4 | -3.0 26.6 350 24 12 8.5 4.7
10000 -3.0 26.6 345 15 8 11.7 6.4 | -2.3 27.9 350 23 12 8.8 4.8
9750 -2.2 28.0 345 15 8 9.5 5.2 | -1.8 28.8 350 22 11 6.1 3.4
9500 -1.5 29.3 345 15 7 10.6 5.8 | -1.3 29.7 350 21 11 6.6 3.6
9250 -0.7 30.7 345 14 7 8.4 4.6 | -0.8 30.6 350 19 10 7.5 4.1
9000 -0.1 31.8 345 14 7 9.0 5.0 | -0.1 31.8 350 17 9 9.5 5.2
8750 0.7 33.3 345 14 7 11.4 6.3 | 0.6 33.1 350 17 9 9.8 5.4
8500 1.5 34.7 345 14 7 11.0 6.0 | 1.3 34.3 350 16 8 9.7 5.3
8250 2.3 36.1 350 13 7 10.4 5.7 | 2.0 35.6 350 16 8 9.6 5.3
8000 3.2 37.8 350 13 7 14.6 8.0 | 2.8 37.0 350 15 8 9.8 5.4
7750 4.6 40.3 350 12 6 24.0 13.2 | 3.5 38.3 350 13 7 10.6 5.8
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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