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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 151208
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0608 MDT Monday, April 15, 2024
This forecast is for the Air Force Academy for Monday, April 15, 2024:
If the trigger temperature of 61.0 F/16.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 885 ft/min (4.5 m/s)
Maximum height of thermals.................. 17036 ft MSL (9417 ft AGL)
Forecast maximum temperature................... 68.0 F/20.5 C
Time of trigger temperature.................... 0945 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................. 12470 ft MSL (4851 ft AGL)
Thermal soaring outlook for Tuesday 04/16...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:21:24 / 19:36:50 MDT
Total possible sunshine........... 13 hr 15 min 27 sec (795 min 27 sec)
Altitude of sun at 12:59:07 MDT... 61.17 degrees
Upper air data from numerical model forecast valid on 04/15/2024 at 0600 MDT
Freezing level.................. 13343 ft MSL (5724 ft AGL)
Convective condensation level... 21295 ft MSL (13676 ft AGL)
Lifted condensation level....... 20457 ft MSL (12838 ft AGL)
Lifted index.................... +0.7
K index......................... -17.1
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 -56.6 -69.9 240 57 29 -0.2 -0.1 M M M M M
45000 -56.9 -70.4 240 71 36 -0.5 -0.3 M M M M M
40000 -57.7 -71.9 235 79 40 -0.4 -0.2 M M M M M
38000 -56.1 -69.0 235 78 40 4.1 2.3 M M M M M
36000 -53.6 -64.5 235 77 39 4.1 2.3 M M M M M
34000 -50.4 -58.7 230 73 38 7.4 4.1 M M M M M
32000 -46.0 -50.8 225 68 35 7.4 4.1 M M M M M
30000 -41.3 -42.3 220 62 32 8.4 4.6 26.7 80.0 5.1 M M
29000 -38.8 -37.8 220 59 30 8.4 4.6 26.1 78.9 4.8 M M
28000 -36.2 -33.2 215 56 29 8.4 4.6 25.6 78.1 4.4 M M
27000 -33.7 -28.7 215 53 28 8.4 4.6 25.2 77.4 4.2 M M
26000 -31.2 -24.2 210 51 26 8.4 4.6 24.6 76.3 3.8 M M
25000 -28.6 -19.5 210 48 25 8.4 4.6 24.2 75.5 3.4 M M
24000 -25.5 -13.9 205 45 23 8.7 4.8 23.7 74.6 3.1 M M
23000 -22.8 -9.0 200 42 22 8.7 4.8 23.2 73.8 2.7 M M
22000 -20.2 -4.4 195 39 20 8.7 4.8 22.9 73.2 2.5 M M
21000 -17.7 0.1 195 37 19 8.0 4.4 22.5 72.5 2.2 M M
20000 -15.2 4.6 190 36 19 8.1 4.4 21.9 71.4 1.6 M M
19500 -14.0 6.8 190 36 18 8.1 4.4 21.6 70.9 1.4 M M
19000 -12.8 9.0 190 35 18 8.1 4.5 21.4 70.5 1.2 M M
18500 -11.6 11.1 190 35 18 7.7 4.2 21.1 70.0 1.0 M M
18000 -10.5 13.1 185 35 18 7.7 4.2 20.7 69.3 0.6 M M
17500 -9.3 15.3 185 35 18 7.6 4.2 20.4 68.7 0.3 M M
17000 -8.2 17.2 185 35 18 7.4 4.1 20.0 68.0 -0.0 880 4.5
16500 -7.1 19.2 185 34 18 7.5 4.1 19.6 67.3 -0.4 832 4.2
16000 -6.0 21.2 190 34 17 7.1 3.9 19.2 66.6 -0.8 785 4.0
15500 -5.0 23.0 190 33 17 7.1 3.9 18.8 65.8 -1.2 738 3.7
15000 -3.9 25.0 190 32 17 7.6 4.1 18.4 65.0 -1.6 691 3.5
14500 -2.8 27.0 190 32 16 7.7 4.2 18.0 64.4 -1.9 642 3.3
14000 -1.6 29.1 195 31 16 7.8 4.3 17.7 63.9 -2.3 593 3.0
13500 -0.4 31.3 195 31 16 8.1 4.5 17.4 63.3 -2.6 543 2.8
13000 0.7 33.3 200 31 16 11.7 6.4 17.1 62.8 -2.9 494 2.5
12500 2.2 36.0 200 30 16 5.3 2.9 17.1 62.8 -2.9 435 2.2
12000 3.1 37.6 205 29 15 6.6 3.6 16.6 61.9 -3.5 392 2.0
11750 3.6 38.5 205 29 15 8.5 4.6 16.4 61.6 -3.7 369 1.9
11500 4.3 39.7 210 28 15 7.8 4.3 16.3 61.4 -3.8 342 1.7
11250 4.8 40.6 210 28 14 6.3 3.5 16.1 61.0 -4.0 321 1.6
11000 5.2 41.4 210 27 14 6.8 3.7 15.9 60.6 -4.3 299 1.5
10750 5.7 42.3 215 26 14 6.9 3.8 15.6 60.1 -4.6 277 1.4
10500 6.3 43.3 215 25 13 7.4 4.1 15.4 59.8 -4.8 254 1.3
10250 6.8 44.2 220 25 13 8.2 4.5 15.3 59.5 -5.0 229 1.2
10000 7.4 45.3 220 24 12 8.5 4.7 15.2 59.3 -5.1 203 1.0
9750 8.1 46.6 225 23 12 8.1 4.5 15.1 59.1 -5.2 177 0.9
9500 8.7 47.7 225 22 11 8.0 4.4 14.9 58.9 -5.4 152 0.8
9250 9.3 48.7 230 20 10 7.9 4.3 14.8 58.7 -5.5 127 0.6
9000 9.8 49.6 230 19 10 6.7 3.7 14.6 58.3 -5.7 102 0.5
8750 10.3 50.5 230 18 10 4.5 2.5 14.3 57.8 -6.0 82 0.4
8500 10.5 50.9 235 18 9 1.9 1.1 13.8 56.9 -6.5 67 0.3
8250 10.8 51.4 235 17 9 7.0 3.8 13.3 56.0 -7.0 52 0.3
8000 11.2 52.2 235 16 8 -3.3 -1.8 13.0 55.4 -7.3 32 0.2
7750 9.5 49.1 240 12 6 -42.6 -23.4 10.6 51.1 -9.7 74 0.4
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 * * * * * *
04/15/2024 at 0900 MDT | 04/15/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.7 | CAPE... 0.0 LI... +1.4
CINH... 0.0 K Index... -12.6 | CINH... 0.0 K Index... -5.1
|
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 -54.2 -65.6 240 51 26 -0.6 -0.3 | -53.5 -64.3 235 42 22 0.3 0.2
45000 -55.1 -67.2 230 67 34 -0.8 -0.4 | -53.1 -63.6 230 67 35 -0.2 -0.1
40000 -56.4 -69.5 220 74 38 -0.8 -0.5 | -53.8 -64.8 215 69 35 -0.5 -0.3
38000 -55.2 -67.4 220 78 40 3.6 2.0 | -52.9 -63.2 210 71 37 2.8 1.5
36000 -53.0 -63.4 220 83 43 3.6 2.0 | -51.3 -60.3 210 75 39 2.8 1.5
34000 -50.3 -58.5 215 85 44 6.9 3.8 | -49.3 -56.7 210 79 40 6.1 3.4
32000 -46.1 -51.0 215 81 42 7.0 3.8 | -45.7 -50.3 205 82 42 5.9 3.3
30000 -41.8 -43.2 210 77 40 8.0 4.4 | -42.0 -43.6 205 85 44 7.8 4.3
29000 -39.4 -38.9 210 74 38 8.0 4.4 | -39.7 -39.5 205 83 43 7.6 4.2
28000 -37.0 -34.6 210 70 36 8.0 4.4 | -37.4 -35.3 205 82 42 7.6 4.2
27000 -34.6 -30.3 205 67 35 8.1 4.4 | -35.1 -31.2 200 81 42 7.6 4.2
26000 -32.1 -25.8 205 63 32 8.1 4.4 | -33.2 -27.8 200 76 39 5.7 3.2
25000 -29.1 -20.4 200 58 30 8.1 4.4 | -31.1 -24.0 195 69 36 5.8 3.2
24000 -26.7 -16.1 195 55 28 7.9 4.3 | -29.4 -20.9 195 64 33 6.4 3.5
23000 -24.3 -11.7 190 51 27 7.8 4.3 | -27.1 -16.8 195 61 31 7.8 4.3
22000 -22.0 -7.6 185 48 25 7.8 4.3 | -24.7 -12.5 190 59 30 7.8 4.3
21000 -19.7 -3.5 180 46 24 7.6 4.2 | -22.4 -8.3 190 56 29 7.9 4.3
20000 -17.4 0.7 185 45 23 7.6 4.2 | -20.0 -4.0 190 54 28 7.9 4.3
19500 -16.2 2.8 185 44 23 7.6 4.2 | -18.8 -1.8 190 53 27 7.9 4.3
19000 -15.1 4.8 185 43 22 7.6 4.2 | -17.7 0.1 190 52 27 7.9 4.3
18500 -13.9 7.0 185 43 22 8.0 4.4 | -16.5 2.3 185 50 26 7.8 4.3
18000 -12.7 9.1 185 43 22 8.1 4.5 | -15.3 4.5 185 49 25 7.7 4.2
17500 -11.5 11.3 185 44 22 8.1 4.4 | -14.2 6.4 185 48 25 7.5 4.1
17000 -10.3 13.5 185 43 22 7.8 4.3 | -12.9 8.8 185 46 24 9.4 5.1
16500 -9.2 15.4 185 43 22 7.8 4.3 | -11.6 11.1 185 45 23 9.2 5.0
16000 -8.0 17.6 190 42 22 8.1 4.4 | -10.2 13.6 185 44 23 9.0 5.0
15500 -6.8 19.8 190 41 21 8.1 4.5 | -8.8 16.2 190 42 22 8.9 4.9
15000 -5.6 21.9 190 41 21 8.2 4.5 | -7.5 18.5 190 41 21 8.4 4.6
14500 -4.3 24.3 190 39 20 8.3 4.5 | -6.4 20.5 195 39 20 7.0 3.8
14000 -3.1 26.4 195 38 20 8.1 4.4 | -5.4 22.3 200 38 20 7.1 3.9
13500 -2.0 28.4 195 37 19 7.6 4.2 | -4.1 24.6 205 35 18 9.1 5.0
13000 -0.9 30.4 200 35 18 11.5 6.3 | -2.8 27.0 210 32 16 4.6 2.5
12500 0.4 32.7 200 34 18 3.3 1.8 | -2.0 28.4 215 27 14 10.0 5.5
12000 1.1 34.0 205 32 17 4.3 2.4 | -0.7 30.7 220 24 12 8.7 4.8
11750 1.5 34.7 210 32 16 7.2 4.0 | -0.0 32.0 220 22 11 11.2 6.2
11500 2.1 35.8 210 30 15 7.1 3.9 | 0.9 33.6 220 22 11 11.1 6.1
11250 2.5 36.5 215 29 15 4.7 2.6 | 1.6 34.9 220 21 11 8.4 4.6
11000 2.8 37.0 220 27 14 5.2 2.9 | 2.2 36.0 220 21 11 9.0 5.0
10750 3.2 37.8 220 26 13 6.1 3.3 | 2.9 37.2 220 20 10 9.3 5.1
10500 3.7 38.7 225 24 12 7.2 4.0 | 3.6 38.5 220 20 10 10.1 5.5
10250 4.2 39.6 230 22 11 7.6 4.2 | 4.4 39.9 220 20 10 10.2 5.6
10000 4.8 40.6 235 20 10 7.8 4.3 | 5.2 41.4 220 19 10 10.3 5.6
9750 5.4 41.7 240 18 9 8.8 4.8 | 5.9 42.6 220 19 10 10.1 5.5
9500 6.1 43.0 240 16 8 9.8 5.4 | 6.7 44.1 220 19 10 9.8 5.4
9250 6.8 44.2 240 15 8 9.3 5.1 | 7.4 45.3 220 19 10 9.9 5.4
9000 7.5 45.5 245 13 7 9.1 5.0 | 8.1 46.6 220 19 10 9.8 5.4
8750 8.2 46.8 245 12 6 9.0 4.9 | 8.9 48.0 220 18 9 10.5 5.8
8500 8.9 48.0 240 11 6 9.2 5.0 | 9.7 49.5 220 18 9 11.4 6.3
8250 9.5 49.1 240 10 5 8.5 4.7 | 10.5 50.9 215 18 9 10.5 5.8
8000 11.0 51.8 230 7 4 14.2 7.8 | 11.3 52.3 215 17 9 11.1 6.1
7750 12.1 53.8 220 5 3 16.8 9.2 | 15.1 59.2 215 14 7 55.8 30.6
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
04/15/2024 at 1500 MDT | 04/15/2024 at 1800 MDT
|
CAPE... +35.2 LI... +0.1 | CAPE... +48.3 LI... -0.5
CINH... 0.0 K Index... -1.3 | CINH... -0.5 K Index... +5.9
|
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 -52.2 -62.0 240 39 20 1.2 0.6 | -52.0 -61.6 240 31 16 1.8 1.0
45000 -50.4 -58.7 235 64 33 0.6 0.3 | -49.3 -56.7 245 49 25 1.6 0.9
40000 -50.2 -58.4 215 62 32 0.1 0.1 | -47.2 -53.0 235 47 24 1.3 0.7
38000 -49.8 -57.6 210 61 32 1.1 0.6 | -46.7 -52.1 225 44 23 0.4 0.2
36000 -49.2 -56.6 205 59 31 1.1 0.6 | -46.4 -51.5 215 40 21 0.4 0.2
34000 -48.3 -54.9 205 58 30 5.5 3.0 | -46.2 -51.2 200 38 20 2.3 1.3
32000 -44.9 -48.8 205 60 31 5.8 3.2 | -43.7 -46.7 200 34 18 4.1 2.2
30000 -41.4 -42.5 205 62 32 5.8 3.2 | -41.3 -42.3 195 30 16 4.2 2.3
29000 -39.6 -39.3 205 63 33 5.8 3.2 | -39.9 -39.8 195 31 16 4.4 2.4
28000 -37.9 -36.2 205 64 33 5.8 3.2 | -38.6 -37.5 200 31 16 4.4 2.4
27000 -36.2 -33.2 200 65 34 5.8 3.2 | -37.3 -35.1 200 32 16 4.3 2.4
26000 -34.6 -30.3 200 63 33 4.8 2.6 | -36.1 -33.0 200 31 16 3.6 2.0
25000 -32.8 -27.0 200 58 30 4.8 2.6 | -34.8 -30.6 205 30 15 3.6 2.0
24000 -31.4 -24.5 200 54 28 4.6 2.5 | -33.7 -28.7 210 28 15 3.6 2.0
23000 -29.6 -21.3 200 50 26 6.3 3.5 | -32.2 -26.0 210 27 14 6.1 3.4
22000 -27.7 -17.9 205 47 24 6.3 3.5 | -30.3 -22.5 215 26 13 6.2 3.4
21000 -25.8 -14.4 205 44 22 6.9 3.8 | -28.5 -19.3 220 24 13 6.1 3.4
20000 -23.4 -10.1 205 42 21 8.2 4.5 | -26.1 -15.0 220 23 12 8.3 4.5
19500 -22.2 -8.0 205 41 21 8.2 4.5 | -24.9 -12.8 225 22 11 8.3 4.5
19000 -21.0 -5.8 205 40 21 8.2 4.5 | -23.7 -10.7 225 21 11 8.3 4.5
18500 -19.7 -3.5 205 39 20 8.3 4.5 | -22.4 -8.3 225 20 10 8.2 4.5
18000 -18.4 -1.1 205 38 20 9.0 4.9 | -21.2 -6.2 225 20 10 9.1 5.0
17500 -17.1 1.2 210 38 19 8.9 4.9 | -19.8 -3.6 225 20 10 9.1 5.0
17000 -15.8 3.6 210 36 19 8.5 4.7 | -18.5 -1.3 225 20 10 8.9 4.9
16500 -14.5 5.9 210 35 18 8.4 4.6 | -17.2 1.0 225 21 11 8.8 4.9
16000 -13.3 8.1 215 33 17 8.8 4.8 | -15.9 3.4 225 22 11 8.9 4.9
15500 -11.9 10.6 215 32 16 9.2 5.1 | -14.5 5.9 225 23 12 9.1 5.0
15000 -10.6 12.9 220 30 16 9.3 5.1 | -13.2 8.2 225 24 13 9.0 4.9
14500 -9.2 15.4 220 29 15 9.7 5.3 | -11.8 10.8 225 25 13 9.9 5.4
14000 -7.7 18.1 220 29 15 9.4 5.2 | -10.3 13.5 225 26 13 9.6 5.3
13500 -6.1 21.0 220 28 14 12.5 6.9 | -8.7 16.3 225 26 13 12.2 6.7
13000 -4.2 24.4 220 28 14 11.1 6.1 | -6.9 19.6 225 26 14 13.8 7.6
12500 -3.3 26.1 220 27 14 6.4 3.5 | -5.9 21.4 225 27 14 3.8 2.1
12000 -1.8 28.8 220 27 14 8.9 4.9 | -4.5 23.9 225 27 14 8.5 4.7
11750 -1.1 30.0 220 27 14 13.0 7.1 | -3.7 25.3 225 27 14 12.6 6.9
11500 -0.0 32.0 220 27 14 11.9 6.6 | -2.7 27.1 220 27 14 12.0 6.6
11250 0.6 33.1 220 27 14 7.5 4.1 | -2.0 28.4 220 27 14 8.1 4.4
11000 1.2 34.2 220 27 14 8.5 4.7 | -1.4 29.5 220 27 14 9.1 5.0
10750 1.9 35.4 220 26 14 9.0 4.9 | -0.7 30.7 220 27 14 8.9 4.9
10500 2.6 36.7 220 26 14 10.6 5.8 | -0.0 32.0 220 27 14 9.2 5.0
10250 3.4 38.1 220 26 13 10.2 5.6 | 0.7 33.3 220 27 14 9.9 5.4
10000 4.1 39.4 220 26 13 9.5 5.2 | 1.4 34.5 220 27 14 10.2 5.6
9750 4.9 40.8 220 26 13 9.8 5.4 | 2.2 36.0 220 27 14 10.2 5.6
9500 5.6 42.1 215 26 13 10.2 5.6 | 3.0 37.4 220 27 14 10.7 5.9
9250 6.4 43.5 215 26 13 10.4 5.7 | 3.8 38.8 220 27 14 10.4 5.7
9000 7.2 45.0 215 25 13 10.2 5.6 | 5.2 41.4 215 27 14 9.7 5.3
8750 7.9 46.2 215 25 13 10.7 5.9 | 6.0 42.8 215 26 14 10.8 5.9
8500 9.6 49.3 215 24 13 11.8 6.5 | 6.8 44.2 215 26 13 11.2 6.2
8250 10.4 50.7 215 24 12 8.4 4.6 | 7.6 45.7 215 25 13 8.6 4.7
8000 11.1 52.0 215 23 12 14.4 7.9 | 8.2 46.8 215 24 12 10.1 5.6
7750 14.3 57.7 215 19 10 90.1 49.4 | 10.0 50.0 215 19 10 49.9 27.4
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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