Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
631
UXUS97 KPUB 011217
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0617 MDT Tuesday, April 1, 2025
This forecast is for the Air Force Academy for Tuesday, April 1, 2025:
If the trigger temperature of 45.4 F/7.4 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 889 ft/min (4.5 m/s)
Maximum height of thermals.................. 17844 ft MSL (10231 ft AGL)
Forecast maximum temperature................... 52.0 F/11.6 C
Time of trigger temperature.................... 0945 MDT
Time of overdevelopment........................ 1200 MDT
Middle/high clouds during soaring window....... Overcast thin high
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 12984 ft MSL (5371 ft AGL)
Thermal soaring outlook for Wednesday 04/02.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:42:51 / 19:23:03 MDT
Total possible sunshine........... 12 hr 40 min 12 sec (760 min 12 sec)
Altitude of sun at 13:02:57 MDT... 55.87 degrees
Upper air data from numerical model forecast valid on 04/01/2025 at 0600 MDT
Freezing level.................. 9858 ft MSL (2245 ft AGL)
Convective condensation level... 14207 ft MSL (6594 ft AGL)
Lifted condensation level....... 15216 ft MSL (7603 ft AGL)
Lifted index.................... -2.2
K index......................... +19.0
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 -54.1 -65.4 255 26 13 -0.9 -0.5 M M M M M
45000 -55.5 -67.9 255 40 21 -0.8 -0.4 M M M M M
40000 -53.9 -65.0 265 80 41 1.3 0.7 M M M M M
38000 -53.1 -63.6 265 97 50 1.4 0.8 M M M M M
36000 -52.2 -62.0 260 110 57 1.4 0.8 M M M M M
34000 -51.2 -60.2 255 125 64 1.2 0.6 M M M M M
32000 -48.7 -55.7 255 125 64 4.6 2.5 M M M M M
30000 -46.0 -50.8 255 123 64 4.7 2.6 M M M M M
29000 -44.6 -48.3 255 116 60 4.5 2.5 20.9 69.7 7.6 M M
28000 -43.3 -45.9 255 106 55 4.5 2.5 18.9 65.9 6.1 M M
27000 -41.9 -43.4 255 97 50 4.5 2.5 17.0 62.5 4.6 M M
26000 -40.2 -40.4 255 87 45 8.7 4.8 15.5 59.9 3.5 M M
25000 -37.7 -35.9 255 78 40 8.4 4.6 14.9 58.9 3.1 M M
24000 -35.2 -31.4 255 69 35 8.4 4.6 14.4 58.0 2.7 M M
23000 -32.7 -26.9 255 60 31 8.6 4.7 14.0 57.2 2.4 M M
22000 -30.2 -22.4 255 54 28 8.6 4.7 13.5 56.4 2.0 M M
21000 -27.0 -16.6 255 47 24 8.6 4.7 13.1 55.5 1.6 M M
20000 -24.6 -12.3 255 43 22 8.1 4.4 12.5 54.5 1.1 M M
19500 -23.4 -10.1 255 41 21 8.1 4.4 12.2 54.0 0.8 M M
19000 -22.2 -8.0 255 40 20 8.1 4.4 11.9 53.5 0.6 M M
18500 -21.0 -5.8 255 38 20 8.1 4.4 11.7 53.0 0.3 M M
18000 -19.8 -3.6 255 36 19 7.6 4.2 11.4 52.5 0.1 M M
17500 -18.7 -1.7 255 35 18 7.5 4.1 11.0 51.8 -0.3 950 4.8
17000 -17.6 0.3 250 33 17 7.3 4.0 10.6 51.1 -0.7 903 4.6
16500 -16.6 2.1 250 32 16 7.0 3.8 10.2 50.3 -1.1 857 4.4
16000 -15.5 4.1 250 30 16 6.8 3.7 9.7 49.5 -1.5 811 4.1
15500 -14.4 6.1 250 27 14 8.9 4.9 9.4 49.0 -1.8 761 3.9
15000 -13.1 8.4 245 23 12 8.7 4.8 9.2 48.6 -2.0 707 3.6
14500 -11.8 10.8 240 19 10 8.7 4.7 9.1 48.4 -2.2 654 3.3
14000 -10.5 13.1 240 19 10 8.6 4.7 8.9 48.0 -2.4 601 3.1
13500 -9.2 15.4 245 20 10 7.8 4.3 8.7 47.7 -2.6 548 2.8
13000 -8.2 17.2 250 21 11 6.6 3.6 8.3 47.0 -3.0 501 2.5
12500 -6.7 19.9 255 24 12 11.0 6.0 8.3 47.0 -3.0 444 2.3
12000 -5.5 22.1 260 27 14 8.1 4.4 8.1 46.5 -3.3 393 2.0
11750 -4.9 23.2 260 28 15 7.9 4.3 7.9 46.3 -3.4 368 1.9
11500 -4.3 24.3 260 30 15 10.7 5.9 7.9 46.2 -3.5 341 1.7
11250 -3.4 25.9 265 31 16 10.4 5.7 8.0 46.4 -3.4 308 1.6
11000 -2.8 27.0 265 33 17 7.8 4.3 7.9 46.2 -3.5 282 1.4
10750 -2.2 28.0 265 34 18 8.8 4.8 7.8 46.0 -3.7 256 1.3
10500 -1.6 29.1 265 35 18 7.5 4.1 7.7 45.9 -3.8 230 1.2
10250 -1.1 30.0 265 35 18 7.1 3.9 7.5 45.4 -4.0 208 1.1
10000 -0.5 31.1 260 35 18 7.9 4.4 7.3 45.2 -4.2 183 0.9
9750 0.1 32.2 260 35 18 7.8 4.3 7.2 44.9 -4.3 159 0.8
9500 0.6 33.1 260 35 18 7.4 4.1 7.0 44.6 -4.5 134 0.7
9250 1.1 34.0 260 37 19 6.1 3.4 6.8 44.2 -4.8 112 0.6
9000 1.5 34.7 255 38 19 5.3 2.9 6.5 43.7 -5.1 93 0.5
8750 1.9 35.4 255 37 19 5.3 2.9 6.1 43.0 -5.5 74 0.4
8500 2.3 36.1 255 37 19 4.2 2.3 5.8 42.4 -5.9 56 0.3
8250 2.5 36.5 255 34 17 2.8 1.5 5.3 41.5 -6.3 41 0.2
8000 2.8 37.0 255 30 16 5.9 3.2 4.8 40.7 -6.8 25 0.1
7750 3.3 37.9 255 26 14 3.2 1.7 4.6 40.2 -7.1 4 0.0
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 * * * * * *
04/01/2025 at 0900 MDT | 04/01/2025 at 1200 MDT
|
CAPE... +38.9 LI... -0.6 | CAPE... +48.1 LI... +0.2
CINH... -61.2 K Index... +4.2 | CINH... -2.8 K Index... +17.4
|
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 -54.8 -66.6 235 24 12 -1.1 -0.6 | -53.8 -64.8 225 24 12 -0.6 -0.3
45000 -56.4 -69.5 235 43 22 -1.1 -0.6 | -54.7 -66.5 240 52 27 -0.5 -0.3
40000 -56.5 -69.7 255 82 42 0.1 0.0 | -54.1 -65.4 250 69 36 0.5 0.3
38000 -56.0 -68.8 255 98 51 4.4 2.4 | -53.6 -64.5 250 78 40 3.0 1.6
36000 -53.6 -64.5 255 105 54 4.0 2.2 | -52.0 -61.6 250 100 51 2.7 1.5
34000 -50.9 -59.6 250 113 58 4.0 2.2 | -50.2 -58.4 250 124 64 2.6 1.4
32000 -48.5 -55.3 250 114 59 4.0 2.2 | -48.0 -54.4 250 122 63 3.8 2.1
30000 -46.2 -51.2 250 113 58 4.0 2.2 | -45.8 -50.4 250 116 60 3.7 2.1
29000 -44.5 -48.1 250 107 55 6.1 3.4 | -44.6 -48.3 250 109 56 3.8 2.1
28000 -42.6 -44.7 250 100 51 6.1 3.4 | -43.5 -46.3 250 100 51 3.8 2.1
27000 -40.8 -41.4 250 92 48 6.1 3.4 | -42.4 -44.3 250 91 47 3.7 2.1
26000 -38.8 -37.8 250 86 44 8.2 4.5 | -40.9 -41.6 245 82 42 10.0 5.5
25000 -36.4 -33.5 250 83 43 8.0 4.4 | -38.0 -36.4 240 72 37 9.6 5.3
24000 -34.0 -29.2 250 79 41 8.0 4.4 | -35.1 -31.2 235 62 32 9.6 5.3
23000 -31.6 -24.9 250 75 39 7.1 3.9 | -32.3 -26.1 230 53 27 8.1 4.5
22000 -29.5 -21.1 250 69 35 7.1 3.9 | -30.0 -22.0 230 51 26 7.9 4.4
21000 -27.4 -17.3 255 62 32 7.1 3.9 | -27.0 -16.6 225 48 25 8.0 4.4
20000 -24.7 -12.5 255 55 28 7.1 3.9 | -24.9 -12.8 230 47 24 6.8 3.7
19500 -23.7 -10.7 255 52 27 7.1 3.9 | -23.9 -11.0 230 46 24 6.8 3.7
19000 -22.6 -8.7 255 48 25 7.1 3.9 | -22.9 -9.2 235 46 24 6.8 3.7
18500 -21.6 -6.9 255 45 23 7.0 3.9 | -21.9 -7.4 235 46 24 6.8 3.7
18000 -20.4 -4.7 250 42 22 9.2 5.0 | -20.8 -5.4 240 45 23 6.6 3.6
17500 -19.0 -2.2 240 39 20 9.9 5.4 | -19.9 -3.8 240 45 23 6.4 3.5
17000 -17.5 0.5 230 37 19 9.9 5.4 | -19.0 -2.2 245 45 23 6.3 3.5
16500 -16.0 3.2 225 36 19 9.7 5.3 | -18.0 -0.4 250 45 23 6.4 3.5
16000 -14.6 5.7 220 35 18 9.8 5.4 | -17.1 1.2 250 44 23 6.3 3.5
15500 -13.2 8.2 220 34 17 8.9 4.9 | -16.1 3.0 250 44 23 8.0 4.4
15000 -11.9 10.6 230 33 17 9.0 4.9 | -14.9 5.2 250 43 22 8.2 4.5
14500 -10.6 12.9 235 34 17 7.4 4.0 | -13.6 7.5 255 42 22 8.6 4.7
14000 -9.6 14.7 245 36 18 6.7 3.7 | -12.3 9.9 250 39 20 8.8 4.8
13500 -8.6 16.5 250 39 20 5.7 3.1 | -11.0 12.2 250 35 18 8.6 4.7
13000 -7.9 17.8 255 39 20 4.1 2.2 | -9.8 14.4 250 34 17 7.7 4.2
12500 -6.8 19.8 260 37 19 9.4 5.2 | -8.2 17.2 250 32 17 13.0 7.2
12000 -5.8 21.6 265 38 19 6.7 3.6 | -6.7 19.9 250 31 16 9.0 5.0
11750 -5.3 22.5 265 38 20 6.3 3.5 | -6.0 21.2 250 31 16 9.2 5.1
11500 -4.8 23.4 265 39 20 9.0 4.9 | -5.2 22.6 250 30 16 11.7 6.4
11250 -4.0 24.8 265 40 21 9.4 5.1 | -4.3 24.3 250 30 15 11.6 6.4
11000 -3.5 25.7 265 40 21 7.2 3.9 | -3.5 25.7 250 29 15 9.7 5.3
10750 -2.9 26.8 270 41 21 8.1 4.5 | -2.8 27.0 250 29 15 10.2 5.6
10500 -2.4 27.7 270 41 21 6.6 3.6 | -2.0 28.4 250 28 15 10.3 5.6
10250 -2.0 28.4 270 40 21 6.8 3.8 | -1.2 29.8 245 28 14 10.1 5.6
10000 -1.4 29.5 265 39 20 8.3 4.6 | -0.5 31.1 245 27 14 9.9 5.4
9750 -0.8 30.6 265 37 19 8.1 4.4 | 0.2 32.4 245 27 14 9.9 5.4
9500 -0.3 31.5 265 36 18 7.9 4.3 | 1.0 33.8 245 26 14 10.1 5.6
9250 0.3 32.5 265 34 17 8.6 4.7 | 1.8 35.2 245 26 13 10.6 5.8
9000 1.0 33.8 265 32 16 10.0 5.5 | 2.5 36.5 245 25 13 10.6 5.8
8750 1.8 35.2 260 29 15 10.4 5.7 | 3.3 37.9 245 25 13 10.4 5.7
8500 2.5 36.5 260 27 14 9.6 5.3 | 4.1 39.4 245 24 13 10.7 5.9
8250 3.2 37.8 255 25 13 9.0 5.0 | 4.9 40.8 245 24 12 11.7 6.4
8000 3.9 39.0 255 23 12 9.3 5.1 | 5.8 42.4 245 23 12 10.9 6.0
7750 4.6 40.3 255 21 11 12.2 6.7 | 6.7 44.1 245 22 11 17.0 9.3
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
04/01/2025 at 1500 MDT | 04/01/2025 at 1800 MDT
|
CAPE... +68.6 LI... +0.3 | CAPE... +150.0 LI... -1.3
CINH... -3.6 K Index... +18.8 | CINH... -1.7 K Index... +19.1
|
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 -54.4 -65.9 255 29 15 -0.3 -0.2 | -53.8 -64.8 235 29 15 0.7 0.4
45000 -54.8 -66.6 235 51 26 -0.3 -0.2 | -52.7 -62.9 230 58 30 0.7 0.4
40000 -53.4 -64.1 240 70 36 1.1 0.6 | -51.6 -60.9 235 65 34 0.8 0.4
38000 -52.7 -62.9 240 78 40 2.1 1.1 | -51.1 -60.0 235 67 35 1.2 0.6
36000 -51.5 -60.7 240 97 50 2.0 1.1 | -50.3 -58.5 240 72 37 1.3 0.7
34000 -50.3 -58.5 245 116 60 2.0 1.1 | -49.5 -57.1 240 77 40 1.3 0.7
32000 -48.6 -55.5 245 126 65 3.2 1.8 | -48.5 -55.3 240 78 40 1.6 0.9
30000 -46.6 -51.9 240 132 68 3.3 1.8 | -47.5 -53.5 240 77 39 1.6 0.9
29000 -45.5 -49.9 245 130 67 4.5 2.5 | -46.9 -52.4 240 72 37 2.7 1.5
28000 -44.1 -47.4 245 121 62 4.5 2.5 | -46.1 -51.0 240 63 33 2.7 1.5
27000 -42.7 -44.9 245 113 58 4.5 2.5 | -45.3 -49.5 245 54 28 2.7 1.5
26000 -41.3 -42.3 245 105 54 6.5 3.5 | -44.4 -47.9 245 45 23 6.8 3.7
25000 -39.0 -38.2 245 97 50 7.7 4.2 | -41.5 -42.7 240 36 19 9.7 5.3
24000 -36.1 -33.0 245 88 45 7.7 4.2 | -38.6 -37.5 235 27 14 9.7 5.3
23000 -33.7 -28.7 245 80 41 9.7 5.3 | -35.7 -32.3 220 19 10 9.1 5.0
22000 -30.9 -23.6 245 70 36 9.5 5.2 | -33.2 -27.8 225 20 10 8.5 4.6
21000 -28.0 -18.4 245 60 31 9.5 5.2 | -30.7 -23.3 225 21 11 8.5 4.7
20000 -25.4 -13.7 240 51 26 7.9 4.3 | -28.3 -18.9 235 23 12 7.2 3.9
19500 -24.3 -11.7 240 47 24 7.9 4.3 | -27.2 -17.0 240 24 12 7.3 4.0
19000 -23.1 -9.6 235 43 22 7.9 4.3 | -26.1 -15.0 250 25 13 7.3 4.0
18500 -21.9 -7.4 235 39 20 7.9 4.3 | -25.0 -13.0 255 26 14 7.3 4.0
18000 -20.7 -5.3 230 35 18 7.7 4.2 | -23.4 -10.1 260 29 15 7.4 4.1
17500 -19.7 -3.5 230 34 18 7.0 3.8 | -22.3 -8.1 265 29 15 7.7 4.2
17000 -18.6 -1.5 235 34 18 7.0 3.9 | -21.1 -6.0 270 29 15 7.6 4.2
16500 -17.6 0.3 240 34 17 6.9 3.8 | -19.9 -3.8 270 28 15 9.3 5.1
16000 -16.6 2.1 245 32 16 7.0 3.8 | -18.5 -1.3 270 26 13 9.2 5.1
15500 -15.5 4.1 250 30 15 7.0 3.8 | -17.2 1.0 270 24 12 9.0 4.9
15000 -14.5 5.9 255 28 14 7.0 3.8 | -15.9 3.4 270 23 12 8.9 4.9
14500 -13.4 7.9 255 26 13 7.2 3.9 | -14.6 5.7 270 22 11 9.0 5.0
14000 -12.3 9.9 255 25 13 7.7 4.2 | -13.2 8.2 270 22 11 9.2 5.1
13500 -11.2 11.8 255 24 12 7.5 4.1 | -11.8 10.8 270 21 11 8.7 4.8
13000 -10.2 13.6 255 23 12 5.6 3.1 | -10.8 12.6 270 21 11 5.6 3.1
12500 -8.9 16.0 255 22 12 12.3 6.8 | -9.3 15.3 270 20 10 14.1 7.8
12000 -7.4 18.7 255 22 11 8.7 4.8 | -7.8 18.0 265 20 10 7.8 4.3
11750 -6.7 19.9 255 22 11 8.6 4.7 | -7.2 19.0 265 20 10 7.7 4.3
11500 -6.0 21.2 255 22 11 11.4 6.3 | -6.5 20.3 265 19 10 12.2 6.7
11250 -5.1 22.8 255 22 11 11.7 6.4 | -5.4 22.3 265 19 10 12.5 6.9
11000 -4.4 24.1 255 21 11 9.3 5.1 | -4.7 23.5 265 19 10 8.8 4.8
10750 -3.6 25.5 255 21 11 10.1 5.5 | -4.0 24.8 265 19 10 9.8 5.4
10500 -2.9 26.8 255 21 11 9.5 5.2 | -3.3 26.1 260 18 9 9.5 5.2
10250 -2.2 28.0 255 21 11 9.6 5.3 | -2.6 27.3 260 18 9 9.8 5.4
10000 -1.4 29.5 255 20 11 10.1 5.5 | -1.9 28.6 260 18 9 9.9 5.5
9750 -0.7 30.7 255 20 10 10.0 5.5 | -1.1 30.0 260 17 9 10.0 5.5
9500 0.1 32.2 255 20 10 10.0 5.5 | -0.4 31.3 260 17 9 9.7 5.3
9250 0.8 33.4 250 20 10 10.2 5.6 | 0.3 32.5 255 17 9 9.2 5.1
9000 1.6 34.9 250 19 10 10.4 5.7 | 1.0 33.8 255 16 8 9.6 5.3
8750 2.4 36.3 250 19 10 10.4 5.7 | 1.8 35.2 255 16 8 10.0 5.5
8500 3.2 37.8 250 18 9 10.4 5.7 | 2.5 36.5 250 15 8 9.7 5.3
8250 3.9 39.0 250 18 9 10.9 6.0 | 3.2 37.8 250 15 8 9.5 5.2
8000 4.9 40.8 250 17 9 17.8 9.8 | 3.9 39.0 245 14 7 10.9 6.0
7750 6.7 44.1 250 15 8 27.9 15.3 | 4.8 40.6 240 12 6 13.3 7.3
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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