Soaring Guidance Issued by NWS Pueblo, CO
000
UXUS97 KPUB 181319
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0719 MDT Monday, March 18, 2024
This forecast is for the Air Force Academy for Monday, March 18, 2024:
If the trigger temperature of 39.4 F/4.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 468 ft/min (2.4 m/s)
Maximum height of thermals.................. 13365 ft MSL (5744 ft AGL)
Forecast maximum temperature................... 45.0 F/7.7 C
Time of trigger temperature.................... 1130 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................. 11603 ft MSL (3982 ft AGL)
Thermal soaring outlook for Tuesday 03/19...... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:04:30 / 19:09:39 MDT
Total possible sunshine........... 12 hr 5 min 9 sec (725 min 9 sec)
Altitude of sun at 13:07:05 MDT... 50.46 degrees
Upper air data from numerical model forecast valid on 03/18/2024 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 15328 ft MSL (7707 ft AGL)
Lifted condensation level....... 14034 ft MSL (6414 ft AGL)
Lifted index.................... +3.7
K index......................... -2.5
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 -58.0 -72.4 295 24 12 0.2 0.1 M M M M M
45000 -57.7 -71.9 300 22 11 0.5 0.3 M M M M M
40000 -60.9 -77.6 035 28 14 -2.3 -1.3 M M M M M
38000 -60.8 -77.4 045 38 20 4.6 2.5 M M M M M
36000 -57.7 -71.9 040 44 23 4.6 2.5 M M M M M
34000 -54.8 -66.6 035 48 25 6.5 3.6 M M M M M
32000 -51.0 -59.8 035 44 22 6.4 3.5 M M M M M
30000 -47.0 -52.6 035 40 21 7.6 4.2 21.6 70.8 11.0 M M
29000 -44.7 -48.5 035 39 20 7.6 4.1 20.6 69.1 10.4 M M
28000 -42.5 -44.5 035 37 19 7.6 4.1 19.8 67.6 9.9 M M
27000 -40.2 -40.4 035 36 18 7.8 4.3 19.1 66.4 9.5 M M
26000 -37.7 -35.9 035 35 18 8.4 4.6 18.5 65.3 9.1 M M
25000 -35.2 -31.4 035 33 17 8.4 4.6 18.0 64.3 8.8 M M
24000 -32.7 -26.9 035 32 17 8.4 4.6 17.6 63.6 8.5 M M
23000 -30.1 -22.2 035 31 16 8.7 4.8 17.1 62.7 8.2 M M
22000 -26.9 -16.4 035 30 16 8.7 4.8 16.6 61.9 8.0 M M
21000 -24.3 -11.7 035 29 15 7.9 4.4 16.2 61.2 7.7 M M
20000 -21.9 -7.4 030 26 13 8.0 4.4 15.6 60.0 7.2 M M
19500 -20.7 -5.3 030 24 12 8.0 4.4 15.3 59.5 7.0 M M
19000 -19.5 -3.1 030 23 12 8.1 4.4 15.0 59.0 6.8 M M
18500 -18.4 -1.1 030 21 11 7.2 3.9 14.7 58.4 6.5 M M
18000 -17.3 0.9 025 20 10 7.2 3.9 14.2 57.6 6.2 M M
17500 -16.3 2.7 025 19 10 6.9 3.8 13.8 56.9 5.8 M M
17000 -15.3 4.5 020 20 10 6.6 3.6 13.3 55.9 5.4 M M
16500 -14.3 6.3 020 20 10 6.5 3.6 12.7 54.9 4.9 M M
16000 -13.5 7.7 015 20 10 5.0 2.7 12.1 53.7 4.3 M M
15500 -12.8 9.0 015 20 10 5.2 2.8 11.3 52.3 3.6 M M
15000 -12.0 10.4 010 20 10 4.5 2.4 10.5 50.9 2.9 M M
14500 -11.4 11.5 005 20 10 4.5 2.5 9.6 49.4 2.1 M M
14000 -10.8 12.6 360 20 10 3.8 2.1 8.8 47.8 1.2 M M
13500 -10.2 13.6 350 20 11 3.6 2.0 7.8 46.0 0.3 M M
13000 -9.7 14.5 345 21 11 3.8 2.1 6.8 44.2 -0.6 447 2.3
12500 -9.2 15.4 345 21 11 3.8 2.1 5.9 42.6 -1.5 416 2.1
12000 -8.6 16.5 340 21 11 5.3 2.9 4.9 40.9 -2.5 385 2.0
11750 -8.2 17.2 340 20 10 6.7 3.7 4.7 40.4 -2.8 364 1.8
11500 -7.7 18.1 340 20 10 5.9 3.2 4.4 39.9 -3.1 343 1.7
11250 -7.4 18.7 340 19 10 4.0 2.2 4.0 39.3 -3.4 325 1.7
11000 -7.1 19.2 340 18 9 5.7 3.1 3.6 38.5 -3.9 309 1.6
10750 -6.5 20.3 340 17 9 7.8 4.3 3.4 38.1 -4.1 285 1.4
10500 -6.0 21.2 340 16 8 7.3 4.0 3.2 37.8 -4.3 261 1.3
10250 -5.5 22.1 340 14 7 6.9 3.8 3.0 37.5 -4.5 238 1.2
10000 -4.9 23.2 335 13 7 8.1 4.5 2.8 37.1 -4.7 215 1.1
9750 -4.2 24.4 330 12 6 9.5 5.2 2.8 37.0 -4.8 187 0.9
9500 -3.6 25.5 325 11 6 9.6 5.3 2.8 37.0 -4.8 159 0.8
9250 -2.9 26.8 320 10 5 7.8 4.3 2.7 36.9 -4.9 131 0.7
9000 -2.4 27.7 320 9 5 7.4 4.0 2.5 36.5 -5.1 108 0.5
8750 -1.7 28.9 315 9 5 9.1 5.0 2.4 36.3 -5.2 82 0.4
8500 -1.1 30.0 315 8 4 8.2 4.5 2.3 36.2 -5.3 56 0.3
8250 -0.6 30.9 310 8 4 5.5 3.0 2.1 35.9 -5.6 33 0.2
8000 -0.8 30.6 310 7 4 -15.8 -8.7 1.2 34.2 -6.5 32 0.2
7750 -3.2 26.2 295 6 3 -46.1 -25.3 -1.9 28.5 -9.7 96 0.5
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 * * * * * *
03/18/2024 at 0900 MDT | 03/18/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.3 | CAPE... 0.0 LI... +3.1
CINH... 0.0 K Index... -4.4 | CINH... 0.0 K Index... -3.0
|
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 -57.9 -72.2 295 23 12 0.2 0.1 | -58.1 -72.6 295 19 10 0.0 0.0
45000 -57.6 -71.7 295 19 10 0.6 0.3 | -58.1 -72.6 295 16 8 0.4 0.2
40000 -62.2 -80.0 040 26 13 -3.1 -1.7 | -62.3 -80.1 055 19 10 -2.8 -1.5
38000 -61.1 -78.0 045 34 17 6.1 3.4 | -61.0 -77.8 060 25 13 6.3 3.4
36000 -57.4 -71.3 045 38 19 6.2 3.4 | -57.2 -71.0 055 27 14 6.3 3.4
34000 -53.8 -64.8 040 40 21 5.9 3.2 | -53.4 -64.1 055 28 14 6.6 3.6
32000 -50.2 -58.4 040 37 19 5.9 3.2 | -49.4 -56.9 055 25 13 6.6 3.6
30000 -46.5 -51.7 040 35 18 7.2 3.9 | -45.4 -49.7 055 24 12 7.2 3.9
29000 -44.4 -47.9 040 34 17 7.2 3.9 | -43.2 -45.8 050 24 12 7.2 3.9
28000 -42.2 -44.0 035 33 17 7.2 3.9 | -41.1 -42.0 050 24 13 7.2 3.9
27000 -40.1 -40.2 035 32 17 7.7 4.2 | -38.9 -38.0 050 25 13 7.4 4.0
26000 -37.6 -35.7 035 31 16 8.3 4.6 | -36.7 -34.1 045 24 12 7.5 4.1
25000 -35.1 -31.2 035 29 15 8.3 4.6 | -34.4 -29.9 045 22 12 7.5 4.1
24000 -32.6 -26.7 030 28 14 8.4 4.6 | -32.2 -26.0 040 21 11 7.8 4.3
23000 -29.4 -20.9 030 25 13 8.5 4.6 | -29.0 -20.2 035 20 10 8.4 4.6
22000 -26.9 -16.4 030 24 12 8.5 4.6 | -26.5 -15.7 035 19 10 8.4 4.6
21000 -24.4 -11.9 030 22 11 8.3 4.5 | -24.0 -11.2 035 18 9 8.0 4.4
20000 -21.9 -7.4 030 22 11 8.3 4.6 | -21.6 -6.9 030 18 9 8.1 4.4
19500 -20.7 -5.3 035 21 11 8.3 4.6 | -20.4 -4.7 030 17 9 8.1 4.4
19000 -19.4 -2.9 035 21 11 8.3 4.6 | -19.2 -2.6 025 17 9 8.1 4.4
18500 -18.2 -0.8 035 20 10 7.9 4.3 | -18.0 -0.4 030 17 9 8.3 4.5
18000 -17.0 1.4 035 19 10 8.0 4.4 | -16.7 1.9 030 16 8 8.3 4.5
17500 -15.8 3.6 035 19 10 7.8 4.3 | -15.5 4.1 030 16 8 8.2 4.5
17000 -14.7 5.5 030 18 9 7.6 4.2 | -14.3 6.3 030 16 8 8.2 4.5
16500 -13.5 7.7 030 17 9 7.5 4.1 | -13.0 8.6 030 15 8 8.1 4.4
16000 -12.5 9.5 025 17 9 6.8 3.7 | -11.8 10.8 030 15 8 7.9 4.3
15500 -11.5 11.3 020 17 9 7.0 3.8 | -10.7 12.7 025 15 8 7.9 4.3
15000 -10.6 12.9 015 17 9 5.1 2.8 | -9.6 14.7 025 16 8 6.6 3.6
14500 -9.8 14.4 010 18 9 5.4 3.0 | -8.6 16.5 020 17 8 6.8 3.7
14000 -9.1 15.6 010 19 10 4.0 2.2 | -7.7 18.1 015 17 9 5.1 2.8
13500 -8.5 16.7 005 19 10 3.9 2.2 | -6.9 19.6 015 18 9 5.2 2.9
13000 -8.0 17.6 360 19 10 2.6 1.4 | -6.2 20.8 010 19 10 4.2 2.3
12500 -7.7 18.1 360 19 10 2.4 1.3 | -5.7 21.7 010 19 10 3.8 2.1
12000 -7.3 18.9 355 19 10 2.7 1.5 | -5.1 22.8 005 18 9 3.0 1.7
11750 -7.1 19.2 355 19 10 2.9 1.6 | -4.9 23.2 005 18 9 2.8 1.5
11500 -6.9 19.6 350 19 10 2.5 1.4 | -4.7 23.5 360 18 9 3.0 1.6
11250 -6.8 19.8 350 18 9 2.4 1.3 | -4.5 23.9 360 17 9 3.0 1.7
11000 -6.5 20.3 345 18 9 5.1 2.8 | -4.3 24.3 355 16 8 2.6 1.4
10750 -6.1 21.0 345 17 9 6.7 3.7 | -4.1 24.6 350 15 8 2.7 1.5
10500 -5.6 21.9 345 16 8 6.4 3.5 | -4.0 24.8 345 15 7 1.9 1.0
10250 -5.2 22.6 345 16 8 6.0 3.3 | -3.8 25.2 340 14 7 5.4 3.0
10000 -4.7 23.5 345 14 7 7.9 4.3 | -3.2 26.2 335 12 6 8.6 4.7
9750 -4.1 24.6 345 13 7 9.6 5.3 | -2.7 27.1 335 11 5 7.5 4.1
9500 -3.4 25.9 345 12 6 9.7 5.3 | -2.1 28.2 330 9 5 7.9 4.4
9250 -2.7 27.1 340 11 6 7.8 4.3 | -1.6 29.1 320 7 4 7.7 4.2
9000 -2.2 28.0 340 10 5 7.0 3.9 | -1.0 30.2 325 8 4 9.7 5.3
8750 -1.6 29.1 335 9 5 8.8 4.8 | -0.1 31.8 325 7 4 11.5 6.3
8500 -1.0 30.2 335 8 4 7.8 4.3 | 0.7 33.3 325 7 4 10.8 5.9
8250 -0.5 31.1 330 8 4 5.4 3.0 | 1.4 34.5 325 7 3 9.4 5.2
8000 -0.3 31.5 330 7 4 0.8 0.5 | 2.2 36.0 325 6 3 12.7 7.0
7750 -0.4 31.3 315 5 3 -3.0 -1.7 | 3.4 38.1 325 6 3 20.8 11.4
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
03/18/2024 at 1500 MDT | 03/18/2024 at 1800 MDT
|
CAPE... +0.2 LI... +2.9 | CAPE... +6.8 LI... +1.7
CINH... 0.0 K Index... +0.2 | CINH... -3.9 K Index... -3.7
|
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 -58.6 -73.5 280 18 9 0.1 0.0 | -59.3 -74.7 275 22 11 0.1 0.1
45000 -58.5 -73.3 280 15 8 0.2 0.1 | -59.2 -74.6 280 19 10 0.2 0.1
40000 -62.4 -80.3 045 13 7 -2.6 -1.5 | -62.0 -79.6 025 9 5 -1.9 -1.0
38000 -61.0 -77.8 055 18 9 6.4 3.5 | -60.5 -76.9 045 13 7 6.0 3.3
36000 -57.1 -70.8 055 18 9 6.4 3.5 | -56.9 -70.4 045 14 7 6.0 3.3
34000 -53.3 -63.9 060 18 9 6.6 3.6 | -53.2 -63.8 045 14 7 6.6 3.6
32000 -49.3 -56.7 055 15 8 6.6 3.6 | -49.2 -56.6 040 13 7 6.6 3.6
30000 -45.2 -49.4 050 14 7 7.5 4.1 | -45.1 -49.2 040 13 6 7.2 3.9
29000 -43.0 -45.4 050 16 8 7.5 4.1 | -42.9 -45.2 040 13 7 7.2 4.0
28000 -40.7 -41.3 050 17 9 7.5 4.1 | -40.8 -41.4 035 13 7 7.2 4.0
27000 -38.5 -37.3 050 18 9 7.4 4.1 | -38.6 -37.5 035 14 7 7.4 4.1
26000 -36.3 -33.3 050 18 9 7.4 4.0 | -36.3 -33.3 040 14 7 7.5 4.1
25000 -34.1 -29.4 050 18 9 7.4 4.0 | -34.1 -29.4 045 14 7 7.6 4.1
24000 -31.9 -25.4 050 18 9 7.6 4.2 | -31.2 -24.2 045 14 7 7.8 4.3
23000 -28.8 -19.8 045 17 9 8.2 4.5 | -28.9 -20.0 045 15 7 7.9 4.3
22000 -26.4 -15.5 045 16 8 8.2 4.5 | -26.5 -15.7 045 15 8 7.9 4.3
21000 -23.9 -11.0 040 15 8 7.9 4.3 | -24.1 -11.4 045 15 8 8.8 4.8
20000 -21.6 -6.9 040 15 8 7.9 4.3 | -21.4 -6.5 045 14 7 8.7 4.8
19500 -20.4 -4.7 035 15 8 7.9 4.3 | -20.1 -4.2 040 14 7 8.7 4.8
19000 -19.2 -2.6 035 15 8 7.9 4.3 | -18.8 -1.8 040 14 7 8.7 4.8
18500 -18.1 -0.6 035 15 8 7.7 4.2 | -17.6 0.3 040 13 7 7.2 4.0
18000 -16.9 1.6 030 14 7 7.7 4.2 | -16.5 2.3 035 13 6 7.4 4.0
17500 -15.8 3.6 030 14 7 7.7 4.2 | -15.4 4.3 035 12 6 7.1 3.9
17000 -14.6 5.7 030 13 7 7.7 4.2 | -14.4 6.1 035 11 6 7.1 3.9
16500 -13.5 7.7 025 13 7 7.7 4.2 | -13.4 7.9 030 10 5 7.1 3.9
16000 -12.3 9.9 025 13 7 7.7 4.2 | -12.3 9.9 025 10 5 7.4 4.1
15500 -11.2 11.8 025 13 7 7.7 4.2 | -11.2 11.8 020 10 5 7.4 4.1
15000 -10.1 13.8 020 14 7 6.8 3.7 | -10.0 14.0 015 10 5 7.7 4.2
14500 -9.0 15.8 020 14 7 7.0 3.9 | -8.9 16.0 015 10 5 7.8 4.3
14000 -8.1 17.4 020 15 8 5.4 3.0 | -7.8 18.0 010 10 5 6.6 3.6
13500 -7.3 18.9 015 15 8 5.4 3.0 | -6.8 19.8 010 10 5 6.5 3.6
13000 -6.5 20.3 015 14 7 5.8 3.2 | -5.8 21.6 010 9 5 6.5 3.6
12500 -5.6 21.9 015 14 7 5.6 3.1 | -4.9 23.2 005 9 4 6.3 3.4
12000 -4.8 23.4 010 13 7 5.7 3.1 | -4.0 24.8 360 8 4 6.5 3.6
11750 -4.4 24.1 005 12 6 5.6 3.1 | -3.5 25.7 360 8 4 6.3 3.5
11500 -4.0 24.8 360 11 6 5.8 3.2 | -3.0 26.6 355 8 4 7.2 4.0
11250 -3.5 25.7 355 11 6 6.1 3.3 | -2.4 27.7 350 7 4 8.3 4.6
11000 -3.1 26.4 350 10 5 6.2 3.4 | -1.8 28.8 345 7 4 6.9 3.8
10750 -2.7 27.1 340 9 5 6.3 3.5 | -1.4 29.5 335 8 4 6.3 3.5
10500 -2.3 27.9 330 8 4 6.2 3.4 | -0.9 30.4 330 8 4 5.7 3.1
10250 -1.9 28.6 320 8 4 7.3 4.0 | -0.4 31.3 320 8 4 8.8 4.8
10000 -1.2 29.8 315 7 3 8.7 4.8 | 0.3 32.5 315 8 4 9.4 5.2
9750 -0.6 30.9 305 5 3 8.7 4.8 | 0.8 33.4 310 8 4 6.6 3.6
9500 0.0 32.0 295 4 2 9.2 5.0 | 1.3 34.3 305 7 4 8.2 4.5
9250 0.7 33.3 270 3 2 7.3 4.0 | 1.8 35.2 300 7 4 5.1 2.8
9000 1.2 34.2 265 3 1 8.8 4.8 | 2.0 35.6 290 5 3 5.3 2.9
8750 2.0 35.6 265 3 1 11.8 6.5 | 2.6 36.7 275 4 2 8.5 4.7
8500 2.8 37.0 260 2 1 10.9 6.0 | 3.1 37.6 250 3 2 7.7 4.2
8250 3.6 38.5 255 2 1 9.5 5.2 | 3.6 38.5 225 3 2 7.6 4.2
8000 4.3 39.7 250 2 1 11.9 6.5 | 4.1 39.4 210 3 2 6.2 3.4
7750 5.5 41.9 245 1 1 18.7 10.3 | 4.4 39.9 195 3 1 5.0 2.7
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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