Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
748
UXUS97 KPUB 051209
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0509 MST Wednesday, February 5, 2025
This forecast is for the Air Force Academy for Wednesday, February 5, 2025:
If the trigger temperature of 55.6 F/13.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 1048 ft/min (5.3 m/s)
Maximum height of thermals.................. 18320 ft MSL (10702 ft AGL)
Forecast maximum temperature................... 62.0 F/17.1 C
Time of trigger temperature.................... 1030 MST
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 12135 ft MSL (4517 ft AGL)
Thermal soaring outlook for Thursday 02/06..... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:01:15 / 17:25:24 MST
Total possible sunshine........... 10 hr 24 min 10 sec (624 min 10 sec)
Altitude of sun at 12:13:19 MST... 35.26 degrees
Upper air data from numerical model forecast valid on 02/05/2025 at 0500 MST
Freezing level.................. 12110 ft MSL (4492 ft AGL)
Convective condensation level... 19057 ft MSL (11439 ft AGL)
Lifted condensation level....... 19157 ft MSL (11539 ft AGL)
Lifted index.................... +1.8
K index......................... -21.4
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 -64.4 -83.9 270 82 42 4.4 2.4 M M M M M
45000 -57.5 -71.5 275 97 50 6.3 3.4 M M M M M
40000 -47.5 -53.5 275 105 54 6.3 3.5 M M M M M
38000 -43.8 -46.8 275 104 53 6.2 3.4 M M M M M
36000 -40.0 -40.0 275 101 52 6.2 3.4 M M M M M
34000 -37.5 -35.5 280 94 49 0.1 0.0 M M M M M
32000 -37.5 -35.5 280 75 39 -0.0 -0.0 M M M M M
30000 -37.1 -34.8 275 60 31 3.1 1.7 33.1 91.6 12.7 M M
29000 -36.2 -33.2 270 58 30 3.1 1.7 30.4 86.7 10.7 M M
28000 -35.3 -31.5 265 57 29 3.1 1.7 27.9 82.2 8.9 M M
27000 -34.3 -29.7 260 56 29 3.4 1.8 25.5 78.0 7.1 M M
26000 -32.9 -27.2 260 55 28 4.8 2.6 23.5 74.3 5.5 M M
25000 -31.1 -24.0 260 53 27 4.8 2.6 21.2 70.1 3.7 M M
24000 -29.7 -21.5 260 51 26 6.0 3.3 19.5 67.1 2.4 M M
23000 -27.5 -17.5 265 54 28 7.3 4.0 18.5 65.4 1.6 M M
22000 -25.3 -13.5 265 56 29 7.3 4.0 17.7 63.8 0.9 M M
21000 -23.0 -9.4 265 57 29 9.2 5.1 17.0 62.6 0.3 M M
20000 -20.2 -4.4 260 49 25 9.4 5.1 16.8 62.3 0.1 M M
19500 -18.8 -1.8 260 46 24 9.4 5.1 16.8 62.2 0.1 M M
19000 -17.4 0.7 260 42 22 9.4 5.1 16.7 62.1 0.0 M M
18500 -16.0 3.2 255 39 20 9.3 5.1 16.7 62.1 0.0 M M
18000 -14.6 5.7 255 36 19 9.3 5.1 16.6 61.9 -0.1 1009 5.1
17500 -13.2 8.2 255 34 17 9.3 5.1 16.6 61.8 -0.1 952 4.8
17000 -11.8 10.8 255 33 17 8.8 4.9 16.4 61.6 -0.2 896 4.6
16500 -10.5 13.1 255 33 17 8.9 4.9 16.3 61.3 -0.4 842 4.3
16000 -9.2 15.4 260 34 17 7.9 4.3 16.1 61.0 -0.6 789 4.0
15500 -8.0 17.6 260 36 19 7.8 4.3 15.8 60.4 -0.9 739 3.8
15000 -6.9 19.6 260 39 20 7.3 4.0 15.5 59.8 -1.2 689 3.5
14500 -5.8 21.6 260 42 22 6.9 3.8 15.0 58.9 -1.6 644 3.3
14000 -4.8 23.4 260 45 23 7.3 4.0 14.5 58.1 -2.1 598 3.0
13500 -3.6 25.5 255 41 21 8.6 4.7 14.2 57.6 -2.4 547 2.8
13000 -2.4 27.7 250 37 19 11.6 6.4 14.0 57.2 -2.6 495 2.5
12500 -0.9 30.4 245 34 17 5.8 3.2 14.1 57.3 -2.6 435 2.2
12000 0.1 32.2 235 30 15 6.4 3.5 13.6 56.4 -3.1 391 2.0
11750 0.6 33.1 230 29 15 7.9 4.4 13.3 56.0 -3.3 369 1.9
11500 1.2 34.2 235 30 15 7.1 3.9 13.2 55.8 -3.4 343 1.7
11250 1.6 34.9 235 31 16 5.2 2.8 12.9 55.2 -3.8 324 1.6
11000 2.0 35.6 240 32 17 5.8 3.2 12.6 54.6 -4.1 304 1.5
10750 2.4 36.3 240 34 18 4.5 2.5 12.2 54.0 -4.5 285 1.4
10500 2.7 36.9 245 38 19 3.7 2.0 11.8 53.2 -5.0 270 1.4
10250 2.9 37.2 250 41 21 4.4 2.4 11.3 52.4 -5.5 255 1.3
10000 3.2 37.8 250 45 23 4.8 2.6 10.9 51.7 -5.9 238 1.2
9750 3.5 38.3 255 48 24 5.0 2.7 10.5 51.0 -6.4 222 1.1
9500 3.9 39.0 255 50 26 5.1 2.8 10.2 50.3 -6.8 205 1.0
9250 4.2 39.6 255 52 27 5.7 3.1 9.8 49.7 -7.2 187 1.0
9000 4.6 40.3 255 53 27 5.9 3.2 9.6 49.2 -7.5 168 0.9
8750 5.0 41.0 255 51 26 4.1 2.2 9.2 48.6 -7.9 149 0.8
8500 5.2 41.4 255 48 25 2.4 1.3 8.7 47.6 -8.4 134 0.7
8250 5.5 41.9 255 45 23 5.2 2.8 8.2 46.7 -9.0 120 0.6
8000 5.8 42.4 255 41 21 1.5 0.8 7.8 46.1 -9.3 101 0.5
7750 5.4 41.7 255 30 16 -14.2 -7.8 6.6 44.0 -10.5 107 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 * * * * * *
02/05/2025 at 0800 MST | 02/05/2025 at 1100 MST
|
CAPE... 0.0 LI... +0.9 | CAPE... 0.0 LI... +3.1
CINH... 0.0 K Index... -24.9 | CINH... 0.0 K Index... -20.7
|
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 -64.2 -83.6 270 76 39 3.9 2.1 | -65.1 -85.2 265 77 39 4.6 2.6
45000 -58.0 -72.4 270 90 46 6.3 3.5 | -57.9 -72.2 270 93 48 6.0 3.3
40000 -47.9 -54.2 275 101 52 6.5 3.6 | -48.3 -54.9 270 112 58 6.1 3.4
38000 -44.6 -48.3 280 103 53 5.2 2.9 | -45.1 -49.2 275 115 59 5.1 2.8
36000 -41.5 -42.7 280 105 54 5.2 2.9 | -42.1 -43.8 280 116 60 5.1 2.8
34000 -39.0 -38.2 285 104 53 1.4 0.8 | -39.8 -39.6 280 114 59 0.9 0.5
32000 -38.2 -36.8 285 97 50 1.4 0.8 | -39.3 -38.7 280 106 55 0.8 0.5
30000 -37.1 -34.8 290 90 46 3.9 2.1 | -38.3 -36.9 285 99 51 4.2 2.3
29000 -35.9 -32.6 290 87 45 3.9 2.2 | -37.0 -34.6 285 97 50 4.3 2.3
28000 -34.7 -30.5 290 84 43 3.9 2.2 | -35.8 -32.4 285 95 49 4.3 2.4
27000 -33.5 -28.3 290 81 41 4.5 2.5 | -34.5 -30.1 285 93 48 5.6 3.1
26000 -31.7 -25.1 290 78 40 6.4 3.5 | -32.2 -26.0 285 90 46 7.9 4.3
25000 -29.3 -20.7 290 75 39 6.4 3.5 | -29.2 -20.6 285 87 45 7.9 4.3
24000 -27.4 -17.3 285 73 38 6.7 3.7 | -26.9 -16.4 290 84 43 7.7 4.2
23000 -25.2 -13.4 285 69 35 7.2 3.9 | -24.6 -12.3 290 80 41 7.5 4.1
22000 -23.1 -9.6 285 65 33 7.2 3.9 | -22.3 -8.1 290 76 39 7.5 4.1
21000 -21.0 -5.8 280 61 31 6.3 3.5 | -20.0 -4.0 295 71 37 7.9 4.3
20000 -19.2 -2.6 285 59 30 6.2 3.4 | -17.7 0.1 290 60 31 7.9 4.3
19500 -18.2 -0.8 285 58 30 6.2 3.4 | -16.5 2.3 290 54 28 7.9 4.3
19000 -17.3 0.9 285 57 29 6.2 3.4 | -15.3 4.5 285 49 25 7.9 4.3
18500 -16.4 2.5 285 56 29 7.2 3.9 | -14.1 6.6 280 44 23 8.7 4.8
18000 -15.2 4.6 280 53 27 7.9 4.3 | -12.7 9.1 280 46 24 9.0 4.9
17500 -14.0 6.8 280 51 26 7.9 4.3 | -11.4 11.5 280 48 25 8.9 4.9
17000 -12.7 9.1 280 47 24 9.4 5.1 | -10.1 13.8 280 51 26 7.4 4.0
16500 -11.3 11.7 280 41 21 9.2 5.1 | -9.0 15.8 280 55 28 7.5 4.1
16000 -9.9 14.2 285 37 19 9.2 5.1 | -7.9 17.8 280 57 29 6.8 3.7
15500 -8.5 16.7 285 34 17 9.2 5.1 | -7.0 19.4 280 55 28 6.7 3.7
15000 -7.1 19.2 285 30 16 8.8 4.8 | -6.0 21.2 280 52 27 5.9 3.2
14500 -5.9 21.4 285 30 15 8.3 4.5 | -5.3 22.5 280 54 28 4.9 2.7
14000 -4.6 23.7 285 29 15 8.2 4.5 | -4.6 23.7 280 56 29 5.2 2.9
13500 -3.4 25.9 275 28 14 8.3 4.6 | -3.6 25.5 280 52 27 7.3 4.0
13000 -2.2 28.0 265 27 14 9.6 5.3 | -2.6 27.3 280 46 24 10.8 5.9
12500 -0.9 30.4 260 28 14 5.6 3.1 | -1.0 30.2 280 42 22 6.3 3.5
12000 -0.1 31.8 250 29 15 4.7 2.6 | 0.1 32.2 275 34 18 6.6 3.6
11750 0.3 32.5 245 29 15 8.7 4.8 | 0.6 33.1 275 31 16 9.4 5.2
11500 1.1 34.0 245 28 15 8.1 4.5 | 1.4 34.5 275 29 15 8.9 4.9
11250 1.4 34.5 245 29 15 3.4 1.9 | 1.9 35.4 275 27 14 5.9 3.2
11000 1.8 35.2 250 30 16 4.7 2.6 | 2.4 36.3 270 26 13 6.7 3.7
10750 2.1 35.8 250 31 16 3.3 1.8 | 2.9 37.2 270 24 12 6.5 3.5
10500 2.2 36.0 255 35 18 2.2 1.2 | 3.4 38.1 270 25 13 6.5 3.6
10250 2.4 36.3 260 38 20 1.3 0.7 | 3.8 38.8 265 26 13 3.4 1.9
10000 2.4 36.3 260 42 21 0.6 0.3 | 3.9 39.0 270 28 15 1.8 1.0
9750 2.3 36.1 265 46 23 0.0 0.0 | 4.0 39.2 270 31 16 -0.4 -0.2
9500 2.2 36.0 265 49 25 -1.2 -0.7 | 3.7 38.7 270 34 18 -3.3 -1.8
9250 2.1 35.8 265 53 27 0.3 0.1 | 3.5 38.3 270 38 19 -1.7 -0.9
9000 2.2 36.0 270 56 29 3.0 1.6 | 3.4 38.1 270 40 21 0.8 0.4
8750 2.4 36.3 270 56 29 5.5 3.0 | 3.5 38.3 270 41 21 5.7 3.1
8500 2.9 37.2 265 52 27 6.3 3.5 | 4.1 39.4 270 40 20 8.4 4.6
8250 3.3 37.9 265 49 25 6.5 3.6 | 4.6 40.3 270 38 20 6.9 3.8
8000 3.8 38.8 265 45 23 5.9 3.2 | 5.1 41.2 265 36 19 9.2 5.1
7750 4.1 39.4 265 35 18 2.5 1.4 | 6.1 43.0 265 30 15 16.8 9.2
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
02/05/2025 at 1400 MST | 02/05/2025 at 1700 MST
|
CAPE... 0.0 LI... +1.0 | CAPE... 0.0 LI... -0.0
CINH... 0.0 K Index... -27.5 | CINH... 0.0 K Index... -21.9
|
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 -65.4 -85.7 265 80 41 4.1 2.2 | -66.0 -86.8 265 78 40 5.2 2.9
45000 -58.9 -74.0 265 97 50 6.4 3.5 | -57.9 -72.2 265 90 46 6.6 3.6
40000 -48.7 -55.7 275 110 56 6.6 3.6 | -47.4 -53.3 275 111 57 6.8 3.7
38000 -45.5 -49.9 275 114 59 5.0 2.7 | -44.7 -48.5 275 117 60 4.2 2.3
36000 -42.5 -44.5 280 119 61 5.0 2.7 | -42.1 -43.8 275 124 64 4.2 2.3
34000 -40.1 -40.2 280 122 63 2.1 1.1 | -40.0 -40.0 275 127 65 2.2 1.2
32000 -38.9 -38.0 280 118 61 2.0 1.1 | -38.7 -37.7 275 125 64 2.1 1.2
30000 -37.4 -35.3 280 112 58 4.1 2.2 | -37.1 -34.8 275 119 61 4.2 2.3
29000 -36.1 -33.0 280 105 54 4.2 2.3 | -35.9 -32.6 275 110 57 4.3 2.3
28000 -34.9 -30.8 275 97 50 4.2 2.3 | -34.6 -30.3 275 102 52 4.3 2.3
27000 -33.6 -28.5 275 90 46 5.4 3.0 | -33.3 -27.9 270 93 48 4.6 2.5
26000 -31.4 -24.5 275 88 45 7.3 4.0 | -31.8 -25.2 270 87 45 5.2 2.8
25000 -28.7 -19.7 275 86 44 7.3 4.0 | -30.2 -22.4 270 81 42 5.2 2.8
24000 -26.5 -15.7 275 84 43 6.8 3.7 | -28.2 -18.8 275 74 38 6.1 3.3
23000 -24.6 -12.3 280 77 39 6.4 3.5 | -26.2 -15.2 275 71 37 6.8 3.7
22000 -22.7 -8.9 285 69 36 6.4 3.5 | -24.2 -11.6 275 68 35 6.8 3.7
21000 -20.7 -5.3 285 63 32 7.8 4.3 | -22.1 -7.8 275 65 34 7.6 4.2
20000 -18.3 -0.9 285 60 31 7.9 4.3 | -19.8 -3.6 275 63 33 7.7 4.2
19500 -17.1 1.2 285 59 30 7.9 4.3 | -18.6 -1.5 275 62 32 7.7 4.2
19000 -15.9 3.4 285 57 29 7.9 4.3 | -17.5 0.5 275 61 31 7.7 4.2
18500 -14.8 5.4 285 56 29 7.5 4.1 | -16.3 2.7 275 60 31 8.9 4.9
18000 -13.7 7.3 285 55 28 7.3 4.0 | -14.9 5.2 275 59 31 9.4 5.1
17500 -12.6 9.3 285 54 28 7.5 4.1 | -13.5 7.7 270 59 30 9.4 5.2
17000 -11.3 11.7 285 52 27 9.1 5.0 | -12.1 10.2 270 59 30 9.2 5.1
16500 -10.0 14.0 285 48 25 8.9 4.9 | -10.7 12.7 270 60 31 9.2 5.1
16000 -8.6 16.5 285 46 24 9.6 5.3 | -9.3 15.3 270 58 30 9.7 5.3
15500 -7.1 19.2 280 45 23 9.6 5.3 | -7.8 18.0 265 54 28 9.7 5.3
15000 -5.7 21.7 280 45 23 8.9 4.9 | -6.3 20.7 265 51 26 9.5 5.2
14500 -4.5 23.9 275 47 24 8.1 4.5 | -4.9 23.2 265 47 24 9.2 5.0
14000 -3.3 26.1 275 50 25 7.7 4.2 | -3.5 25.7 265 44 23 8.2 4.5
13500 -2.3 27.9 275 51 26 6.4 3.5 | -2.7 27.1 270 45 23 5.3 2.9
13000 -1.3 29.7 275 53 27 8.5 4.7 | -1.9 28.6 275 48 25 6.3 3.5
12500 -0.1 31.8 270 52 27 5.8 3.2 | -1.0 30.2 275 47 24 5.3 2.9
12000 0.8 33.4 270 47 24 5.9 3.2 | -0.2 31.6 275 44 23 5.2 2.9
11750 1.3 34.3 270 45 23 8.7 4.8 | 0.3 32.5 275 43 22 8.2 4.5
11500 2.0 35.6 265 41 21 7.8 4.3 | 1.0 33.8 270 41 21 8.6 4.7
11250 2.4 36.3 265 39 20 4.3 2.4 | 1.5 34.7 270 37 19 6.6 3.6
11000 2.7 36.9 265 37 19 5.5 3.0 | 2.0 35.6 270 34 18 7.1 3.9
10750 3.1 37.6 260 36 18 4.4 2.4 | 2.5 36.5 265 31 16 6.9 3.8
10500 3.4 38.1 260 38 19 3.6 2.0 | 3.0 37.4 265 28 14 7.0 3.8
10250 3.6 38.5 260 40 20 2.5 1.4 | 3.5 38.3 265 25 13 4.4 2.4
10000 3.7 38.7 260 41 21 2.0 1.1 | 3.6 38.5 265 26 13 2.6 1.4
9750 3.8 38.8 265 43 22 0.7 0.4 | 3.7 38.7 265 27 14 0.3 0.1
9500 3.7 38.7 265 43 22 -1.5 -0.8 | 3.6 38.5 270 30 15 -2.2 -1.2
9250 3.6 38.5 265 43 22 1.2 0.6 | 3.4 38.1 270 32 17 -0.7 -0.4
9000 3.8 38.8 265 42 22 5.5 3.0 | 3.4 38.1 270 35 18 1.9 1.0
8750 4.3 39.7 265 40 21 9.0 4.9 | 3.6 38.5 270 36 19 5.6 3.1
8500 5.0 41.0 265 38 20 10.8 5.9 | 4.1 39.4 265 35 18 6.8 3.7
8250 5.8 42.4 265 37 19 9.7 5.3 | 4.6 40.3 265 34 18 7.0 3.9
8000 6.5 43.7 265 35 18 11.4 6.2 | 5.1 41.2 265 33 17 5.6 3.0
7750 8.9 48.0 265 20 10 16.2 8.9 | 5.3 41.5 265 25 13 0.6 0.3
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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