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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 221227
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0627 MDT Monday, April 22, 2024
This forecast is for the Air Force Academy for Monday, April 22, 2024:
If the trigger temperature of 59.2 F/15.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1644 ft/min (8.3 m/s)
Maximum height of thermals.................. 26119 ft MSL (18526 ft AGL)
Forecast maximum temperature................... 75.0 F/24.3 C
Time of trigger temperature.................... 0930 MDT
Time of overdevelopment........................ 1100 MDT
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 21207 ft MSL (13614 ft AGL)
Thermal soaring outlook for Tuesday 04/23...... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:11:38 / 19:43:39 MDT
Total possible sunshine........... 13 hr 32 min 1 sec (812 min 1 sec)
Altitude of sun at 12:57:38 MDT... 63.57 degrees
Upper air data from numerical model forecast valid on 04/22/2024 at 0600 MDT
Freezing level.................. 13000 ft MSL (5407 ft AGL)
Convective condensation level... 18725 ft MSL (11132 ft AGL)
Lifted condensation level....... 20796 ft MSL (13203 ft AGL)
Lifted index.................... -3.7
K index......................... -9.7
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 -58.4 -73.1 295 46 23 0.5 0.3 M M M M M
45000 -57.6 -71.7 290 60 31 -1.3 -0.7 M M M M M
40000 -63.8 -82.8 290 54 28 -3.8 -2.1 M M M M M
38000 -61.3 -78.3 290 52 27 7.8 4.3 M M M M M
36000 -56.6 -69.9 290 50 26 7.8 4.3 M M M M M
34000 -51.8 -61.2 285 48 25 8.2 4.5 M M M M M
32000 -46.9 -52.4 290 44 23 8.2 4.5 M M M M M
30000 -41.9 -43.4 290 41 21 8.4 4.6 26.3 79.3 1.8 M M
29000 -39.4 -38.9 290 40 21 8.4 4.6 25.7 78.3 1.4 M M
28000 -36.8 -34.2 290 39 20 8.4 4.6 25.3 77.5 1.1 M M
27000 -34.4 -29.9 290 37 19 7.5 4.1 24.8 76.6 0.7 M M
26000 -32.1 -25.8 290 35 18 7.6 4.2 23.9 75.0 -0.0 1840 9.3
25000 -29.8 -21.6 290 34 17 7.6 4.2 23.2 73.7 -0.6 1742 8.8
24000 -27.5 -17.5 290 32 16 7.8 4.3 22.5 72.5 -1.2 1643 8.3
23000 -24.6 -12.3 290 30 15 7.8 4.3 21.5 70.7 -2.0 1518 7.7
22000 -22.2 -8.0 295 28 14 7.8 4.3 20.9 69.6 -2.6 1418 7.2
21000 -19.8 -3.6 295 25 13 8.0 4.4 20.2 68.4 -3.2 1317 6.7
20000 -17.4 0.7 295 23 12 8.0 4.4 19.6 67.3 -3.8 1215 6.2
19500 -16.2 2.8 295 21 11 8.0 4.4 19.3 66.8 -4.0 1164 5.9
19000 -15.0 5.0 295 20 10 8.1 4.5 19.1 66.3 -4.3 1113 5.7
18500 -13.7 7.3 290 18 9 8.7 4.8 18.9 66.0 -4.5 1060 5.4
18000 -12.4 9.7 285 16 8 8.6 4.7 18.7 65.6 -4.7 1007 5.1
17500 -11.1 12.0 270 14 7 9.4 5.2 18.5 65.4 -4.9 952 4.8
17000 -9.7 14.5 250 13 7 9.5 5.2 18.5 65.3 -4.9 894 4.5
16500 -8.2 17.2 230 13 7 9.0 4.9 18.5 65.2 -5.0 837 4.3
16000 -7.0 19.4 230 11 6 8.1 4.4 18.2 64.8 -5.3 785 4.0
15500 -5.8 21.6 235 9 5 8.1 4.4 17.9 64.3 -5.5 734 3.7
15000 -4.7 23.5 245 7 4 7.5 4.1 17.6 63.7 -5.9 684 3.5
14500 -3.5 25.7 260 6 3 7.6 4.2 17.3 63.1 -6.3 636 3.2
14000 -2.4 27.7 280 6 3 7.8 4.3 16.9 62.5 -6.6 587 3.0
13500 -1.2 29.8 290 8 4 7.8 4.3 16.6 61.9 -7.0 537 2.7
13000 -0.0 32.0 295 10 5 8.9 4.9 16.4 61.4 -7.3 487 2.5
12500 1.1 34.0 305 13 7 7.1 3.9 16.1 61.0 -7.6 437 2.2
12000 2.2 36.0 310 19 10 7.5 4.1 15.7 60.3 -8.0 390 2.0
11750 2.7 36.9 305 20 10 7.4 4.1 15.5 60.0 -8.3 366 1.9
11500 3.3 37.9 305 21 11 8.2 4.5 15.4 59.7 -8.5 342 1.7
11250 3.9 39.0 305 24 12 9.1 5.0 15.3 59.5 -8.6 316 1.6
11000 4.5 40.1 305 26 13 8.6 4.7 15.2 59.4 -8.7 290 1.5
10750 5.2 41.4 305 27 14 8.4 4.6 15.1 59.2 -8.9 264 1.3
10500 5.8 42.4 305 28 14 8.5 4.7 15.0 59.0 -9.0 239 1.2
10250 6.4 43.5 305 29 15 9.5 5.2 15.0 58.9 -9.1 212 1.1
10000 7.1 44.8 305 28 15 8.9 4.9 14.9 58.9 -9.2 184 0.9
9750 7.7 45.9 305 28 15 7.9 4.3 14.8 58.7 -9.4 159 0.8
9500 8.3 46.9 300 28 15 8.1 4.4 14.7 58.4 -9.5 134 0.7
9250 8.9 48.0 300 28 15 8.4 4.6 14.6 58.2 -9.7 109 0.6
9000 9.5 49.1 295 28 15 7.1 3.9 14.4 58.0 -9.8 83 0.4
8750 9.9 49.8 295 28 14 4.6 2.5 14.1 57.4 -10.2 63 0.3
8500 10.3 50.5 290 28 14 8.3 4.5 13.8 56.9 -10.5 43 0.2
8250 10.8 51.4 285 28 14 -4.1 -2.2 13.5 56.3 -10.8 22 0.1
8000 9.3 48.7 285 25 13 -32.1 -17.6 11.3 52.4 -13.0 57 0.3
7750 6.4 43.5 280 17 9 -41.6 -22.8 7.6 45.8 -16.7 138 0.7
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 * * * * * *
04/22/2024 at 0900 MDT | 04/22/2024 at 1200 MDT
|
CAPE... 0.0 LI... +0.5 | CAPE... +340.6 LI... -1.9
CINH... 0.0 K Index... +0.1 | CINH... -0.0 K Index... +19.6
|
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 -58.8 -73.8 295 41 21 -0.5 -0.2 | -58.1 -72.6 295 44 23 0.2 0.1
45000 -59.5 -75.1 295 56 29 -1.4 -0.7 | -58.0 -72.4 295 56 29 -3.6 -2.0
40000 -63.6 -82.5 285 60 31 -2.4 -1.3 | -63.7 -82.7 280 62 32 -3.9 -2.1
38000 -60.7 -77.3 285 58 30 7.9 4.3 | -61.5 -78.7 280 61 32 8.0 4.4
36000 -56.0 -68.8 285 54 28 7.9 4.3 | -56.8 -70.2 280 59 30 8.0 4.4
34000 -51.2 -60.2 285 50 26 8.1 4.4 | -52.0 -61.6 280 57 29 8.1 4.4
32000 -46.4 -51.5 280 47 24 8.1 4.4 | -46.5 -51.7 280 53 27 8.1 4.4
30000 -41.5 -42.7 280 45 23 8.2 4.5 | -41.6 -42.9 280 50 26 8.3 4.5
29000 -39.1 -38.4 280 44 23 8.2 4.5 | -39.1 -38.4 280 48 24 8.3 4.5
28000 -36.6 -33.9 280 43 22 8.2 4.5 | -36.7 -34.1 275 45 23 8.3 4.5
27000 -34.2 -29.6 285 42 22 7.1 3.9 | -34.2 -29.6 275 44 22 7.6 4.2
26000 -32.1 -25.8 280 41 21 7.2 4.0 | -32.0 -25.6 280 42 22 7.6 4.2
25000 -29.9 -21.8 280 40 20 7.2 4.0 | -29.7 -21.5 280 41 21 7.6 4.2
24000 -27.7 -17.9 280 38 20 7.1 3.9 | -27.5 -17.5 280 39 20 6.4 3.5
23000 -25.1 -13.2 275 31 16 7.1 3.9 | -25.6 -14.1 280 36 18 6.4 3.5
22000 -22.9 -9.2 270 26 13 7.1 3.9 | -23.7 -10.7 280 33 17 6.4 3.5
21000 -20.6 -5.1 260 22 12 8.5 4.7 | -21.6 -6.9 280 30 15 8.8 4.8
20000 -18.0 -0.4 255 20 10 8.5 4.7 | -19.1 -2.4 275 27 14 8.6 4.7
19500 -16.7 1.9 250 19 10 8.5 4.7 | -17.1 1.2 275 25 13 8.6 4.7
19000 -15.5 4.1 245 18 10 8.5 4.7 | -15.9 3.4 275 24 12 8.8 4.8
18500 -14.2 6.4 250 17 9 8.3 4.6 | -14.5 5.9 280 25 13 9.2 5.0
18000 -13.0 8.6 255 15 8 8.3 4.6 | -13.2 8.2 280 27 14 9.2 5.1
17500 -11.7 10.9 260 14 7 8.0 4.4 | -11.9 10.6 285 28 14 9.1 5.0
17000 -10.6 12.9 270 12 6 8.0 4.4 | -10.6 12.9 280 27 14 9.1 5.0
16500 -9.4 15.1 285 10 5 8.4 4.6 | -9.2 15.4 280 27 14 9.2 5.0
16000 -8.1 17.4 295 12 6 8.8 4.8 | -7.9 17.8 275 26 13 9.2 5.1
15500 -6.8 19.8 300 14 7 8.9 4.9 | -6.6 20.1 275 25 13 9.3 5.1
15000 -5.5 22.1 305 16 8 8.5 4.7 | -5.1 22.8 270 23 12 9.7 5.3
14500 -4.3 24.3 310 18 9 8.5 4.7 | -3.7 25.3 270 22 11 9.7 5.3
14000 -3.0 26.6 310 21 11 9.3 5.1 | -2.3 27.9 265 21 11 9.6 5.3
13500 -1.6 29.1 310 23 12 9.2 5.1 | -0.8 30.6 265 20 11 9.4 5.2
13000 -0.2 31.6 305 26 13 10.9 6.0 | 0.7 33.3 265 20 10 11.5 6.3
12500 1.2 34.2 305 28 14 8.2 4.5 | 2.2 36.0 265 20 10 9.0 4.9
12000 2.4 36.3 305 30 16 8.5 4.7 | 3.6 38.5 265 19 10 8.9 4.9
11750 3.1 37.6 305 31 16 8.5 4.7 | 4.2 39.6 265 19 10 9.0 5.0
11500 3.7 38.7 300 32 16 9.1 5.0 | 4.9 40.8 265 19 10 10.3 5.7
11250 4.4 39.9 300 33 17 9.6 5.3 | 5.7 42.3 265 19 10 10.8 5.9
11000 5.1 41.2 300 34 17 8.3 4.6 | 6.5 43.7 265 19 10 9.3 5.1
10750 5.7 42.3 300 32 17 7.4 4.1 | 7.1 44.8 265 18 9 8.2 4.5
10500 6.3 43.3 300 31 16 8.2 4.5 | 7.8 46.0 265 18 9 9.5 5.2
10250 6.9 44.4 295 30 15 10.5 5.7 | 8.6 47.5 265 18 9 11.7 6.4
10000 7.7 45.9 295 28 15 9.4 5.1 | 9.4 48.9 265 18 9 10.7 5.9
9750 8.3 46.9 295 28 15 7.4 4.1 | 10.2 50.4 265 18 9 9.5 5.2
9500 8.9 48.0 290 28 14 7.8 4.3 | 10.9 51.6 265 17 9 9.4 5.2
9250 9.5 49.1 290 28 14 8.1 4.5 | 11.6 52.9 260 17 9 10.8 5.9
9000 10.0 50.0 285 28 14 5.7 3.1 | 12.5 54.5 260 17 9 11.2 6.1
8750 10.3 50.5 285 27 14 3.6 2.0 | 13.2 55.8 260 16 8 10.1 5.5
8500 10.6 51.1 280 26 14 3.6 2.0 | 14.0 57.2 260 16 8 10.0 5.5
8250 10.9 51.6 280 26 13 5.5 3.0 | 14.8 58.6 260 16 8 11.4 6.3
8000 11.4 52.5 275 22 11 9.2 5.0 | 15.8 60.4 260 15 8 17.9 9.8
7750 12.1 53.8 270 16 8 8.9 4.9 | 17.4 63.3 260 14 7 24.2 13.3
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
04/22/2024 at 1500 MDT | 04/22/2024 at 1800 MDT
|
CAPE... +275.9 LI... -2.1 | CAPE... +318.9 LI... -2.4
CINH... -0.7 K Index... +23.2 | CINH... -1.8 K Index... +26.5
|
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 -58.2 -72.8 295 50 26 -0.9 -0.5 | -59.0 -74.2 295 45 23 -0.8 -0.4
45000 -59.7 -75.5 290 60 31 -3.0 -1.6 | -60.3 -76.5 290 69 35 -2.0 -1.1
40000 -64.1 -83.4 290 59 30 -2.9 -1.6 | -63.1 -81.6 295 62 32 -1.9 -1.0
38000 -61.4 -78.5 285 58 30 8.5 4.6 | -60.4 -76.7 295 60 31 8.0 4.4
36000 -56.4 -69.5 285 56 29 8.4 4.6 | -55.6 -68.1 290 58 30 8.0 4.4
34000 -50.7 -59.3 285 55 28 8.3 4.5 | -50.2 -58.4 290 56 29 7.9 4.3
32000 -45.8 -50.4 280 53 27 8.3 4.5 | -45.5 -49.9 285 55 28 7.9 4.3
30000 -40.9 -41.6 280 51 26 8.0 4.4 | -40.7 -41.3 285 54 28 8.1 4.4
29000 -38.5 -37.3 280 50 26 8.0 4.4 | -38.3 -36.9 285 53 27 8.1 4.4
28000 -36.1 -33.0 280 49 25 8.0 4.4 | -35.9 -32.6 285 53 27 8.1 4.4
27000 -33.6 -28.5 280 48 25 8.4 4.6 | -33.5 -28.3 280 52 27 8.0 4.4
26000 -31.1 -24.0 280 44 23 8.4 4.6 | -31.1 -24.0 285 50 26 8.0 4.4
25000 -28.6 -19.5 280 41 21 8.4 4.6 | -28.7 -19.7 285 48 25 8.0 4.4
24000 -26.3 -15.3 280 38 20 5.5 3.0 | -26.4 -15.5 285 46 24 6.3 3.5
23000 -24.7 -12.5 280 37 19 5.3 2.9 | -24.5 -12.1 285 43 22 6.1 3.4
22000 -23.2 -9.8 285 36 19 5.4 2.9 | -22.7 -8.9 285 40 20 6.2 3.4
21000 -21.3 -6.3 285 35 18 8.7 4.8 | -20.7 -5.3 280 36 19 8.4 4.6
20000 -18.2 -0.8 280 31 16 8.5 4.7 | -17.7 0.1 275 31 16 8.4 4.6
19500 -17.0 1.4 275 30 15 8.6 4.7 | -16.5 2.3 270 29 15 8.5 4.6
19000 -15.8 3.6 275 29 15 9.0 4.9 | -15.3 4.5 265 27 14 8.8 4.8
18500 -14.4 6.1 270 28 14 9.7 5.3 | -14.0 6.8 265 27 14 9.4 5.2
18000 -13.9 7.0 270 27 14 9.7 5.3 | -12.6 9.3 270 27 14 9.4 5.2
17500 -11.5 11.3 270 26 13 9.5 5.2 | -11.2 11.8 270 26 14 9.5 5.2
17000 -10.1 13.8 270 25 13 9.6 5.2 | -9.9 14.2 270 25 13 9.5 5.2
16500 -8.7 16.3 270 24 13 9.6 5.3 | -8.5 16.7 270 23 12 9.5 5.2
16000 -7.3 18.9 270 24 12 9.7 5.3 | -7.1 19.2 275 22 11 9.4 5.1
15500 -5.8 21.6 270 23 12 9.7 5.3 | -5.7 21.7 280 21 11 9.4 5.2
15000 -4.4 24.1 270 23 12 9.9 5.4 | -4.3 24.3 280 20 10 9.7 5.3
14500 -2.9 26.8 270 22 11 9.9 5.4 | -2.8 27.0 280 19 10 9.7 5.3
14000 -1.4 29.5 275 22 11 9.8 5.4 | -1.4 29.5 285 19 10 9.7 5.3
13500 0.0 32.0 275 22 11 9.6 5.3 | 0.1 32.2 285 19 10 9.5 5.2
13000 1.6 34.9 275 22 11 11.6 6.4 | 1.7 35.1 285 19 10 12.1 6.6
12500 3.1 37.6 275 21 11 8.5 4.7 | 3.1 37.6 285 19 10 8.3 4.6
12000 4.4 39.9 275 21 11 9.4 5.2 | 4.5 40.1 290 18 9 9.4 5.1
11750 5.1 41.2 275 21 11 9.9 5.4 | 5.2 41.4 290 18 9 9.9 5.4
11500 5.9 42.6 275 21 11 10.2 5.6 | 5.9 42.6 290 18 9 9.4 5.2
11250 6.7 44.1 275 21 11 10.5 5.7 | 6.6 43.9 290 18 9 9.3 5.1
11000 7.4 45.3 275 20 10 9.2 5.1 | 7.3 45.1 295 18 9 9.4 5.1
10750 8.0 46.4 275 20 10 8.0 4.4 | 8.0 46.4 295 17 9 9.3 5.1
10500 8.7 47.7 275 20 10 9.3 5.1 | 8.7 47.7 295 17 9 9.7 5.3
10250 9.5 49.1 275 20 10 11.7 6.4 | 9.5 49.1 300 17 9 10.9 6.0
10000 10.3 50.5 275 19 10 10.7 5.9 | 10.3 50.5 300 16 8 10.2 5.6
9750 11.0 51.8 275 19 10 9.2 5.1 | 11.0 51.8 300 16 8 9.3 5.1
9500 11.8 53.2 275 19 10 9.2 5.1 | 11.7 53.1 305 16 8 9.4 5.1
9250 12.5 54.5 280 19 10 10.7 5.9 | 12.4 54.3 305 16 8 10.2 5.6
9000 13.3 55.9 280 18 9 11.1 6.1 | 13.2 55.8 305 15 8 10.2 5.6
8750 14.1 57.4 280 18 9 10.0 5.5 | 13.9 57.0 305 15 8 9.5 5.2
8500 14.8 58.6 280 17 9 9.9 5.5 | 14.6 58.3 310 14 7 9.4 5.1
8250 15.6 60.1 280 17 9 11.2 6.1 | 15.3 59.5 310 14 7 10.7 5.9
8000 16.6 61.9 280 16 8 15.8 8.7 | 16.2 61.2 310 14 7 12.5 6.8
7750 17.9 64.2 280 14 7 19.3 10.6 | 17.1 62.8 310 12 6 11.2 6.2
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
________________________________________________________________________________
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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- Page last modified: Sep 19th, 2023 19:10 UTC