Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
458
UXUS97 KPUB 291204
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0604 MDT Monday, April 29, 2024
This forecast is for the Air Force Academy for Monday, April 29, 2024:
If the trigger temperature of 48.7 F/9.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1129 ft/min (5.7 m/s)
Maximum height of thermals.................. 20119 ft MSL (12517 ft AGL)
Forecast maximum temperature................... 64.0 F/18.2 C
Time of trigger temperature.................... 0930 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................. 17209 ft MSL (9607 ft AGL)
Thermal soaring outlook for Tuesday 04/30...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:02:37 / 19:50:27 MDT
Total possible sunshine........... 13 hr 47 min 50 sec (827 min 50 sec)
Altitude of sun at 12:56:32 MDT... 65.80 degrees
Upper air data from numerical model forecast valid on 04/29/2024 at 0600 MDT
Freezing level.................. 7661 ft MSL (59 ft AGL)
Additional freezing level....... 10460 ft MSL (2858 ft AGL)
Convective condensation level... 14834 ft MSL (7232 ft AGL)
Lifted condensation level....... 17383 ft MSL (9781 ft AGL)
Lifted index.................... -2.0
K index......................... +3.2
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 -55.7 -68.3 270 25 13 0.9 0.5 M M M M M
45000 -54.3 -65.7 285 34 17 -0.8 -0.4 M M M M M
40000 -56.2 -69.2 305 43 22 -1.2 -0.7 M M M M M
38000 -56.0 -68.8 310 47 24 1.9 1.0 M M M M M
36000 -54.8 -66.6 320 51 26 1.9 1.0 M M M M M
34000 -52.7 -62.9 320 54 28 7.5 4.1 M M M M M
32000 -48.1 -54.6 320 52 27 7.7 4.2 M M M M M
30000 -43.4 -46.1 315 49 25 8.1 4.5 25.1 77.2 5.6 M M
29000 -40.9 -41.6 315 47 24 8.1 4.5 24.4 75.9 5.2 M M
28000 -38.5 -37.3 315 44 23 8.1 4.5 23.8 74.9 4.8 M M
27000 -36.1 -33.0 310 42 22 7.7 4.2 23.4 74.0 4.4 M M
26000 -33.9 -29.0 305 38 20 7.3 4.0 22.3 72.1 3.6 M M
25000 -31.8 -25.2 300 35 18 7.3 4.0 21.4 70.5 2.9 M M
24000 -29.6 -21.3 295 31 16 7.5 4.1 20.6 69.0 2.3 M M
23000 -27.2 -17.0 295 29 15 8.2 4.5 19.9 67.8 1.7 M M
22000 -24.7 -12.5 295 28 14 8.2 4.5 19.4 66.9 1.3 M M
21000 -22.2 -8.0 295 26 13 7.4 4.1 18.9 66.1 1.0 M M
20000 -19.7 -3.5 295 24 12 6.8 3.7 17.6 63.6 -0.2 1107 5.6
19500 -18.7 -1.7 295 23 12 6.8 3.7 17.1 62.7 -0.7 1062 5.4
19000 -17.7 0.1 295 22 11 6.8 3.8 16.6 61.9 -1.1 1017 5.2
18500 -16.7 1.9 295 21 11 6.1 3.3 16.1 60.9 -1.5 973 4.9
18000 -15.8 3.6 295 20 10 6.1 3.3 15.4 59.8 -2.1 932 4.7
17500 -14.9 5.2 290 19 10 6.0 3.3 14.8 58.7 -2.7 891 4.5
17000 -14.1 6.6 295 19 10 5.8 3.2 14.2 57.5 -3.4 851 4.3
16500 -13.2 8.2 295 19 10 5.9 3.2 13.5 56.4 -4.0 811 4.1
16000 -12.3 9.9 295 19 10 6.5 3.6 13.0 55.3 -4.6 769 3.9
15500 -11.4 11.5 295 20 10 6.5 3.5 12.4 54.4 -5.1 726 3.7
15000 -10.4 13.3 300 20 10 7.3 4.0 11.9 53.5 -5.7 682 3.5
14500 -9.3 15.3 300 20 10 7.5 4.1 11.6 52.8 -6.1 635 3.2
14000 -8.3 17.1 300 20 10 7.9 4.3 11.2 52.2 -6.5 588 3.0
13500 -7.1 19.2 300 19 10 8.2 4.5 10.9 51.7 -6.8 537 2.7
13000 -5.9 21.4 300 19 10 8.7 4.8 10.7 51.3 -7.1 486 2.5
12500 -4.6 23.7 300 17 9 7.2 4.0 10.5 50.8 -7.3 435 2.2
12000 -3.6 25.5 300 16 8 7.3 4.0 10.1 50.1 -7.8 388 2.0
11750 -3.0 26.6 300 15 8 7.2 4.0 9.9 49.8 -8.0 365 1.9
11500 -2.5 27.5 300 14 7 7.8 4.3 9.7 49.4 -8.2 341 1.7
11250 -1.9 28.6 300 13 7 8.9 4.9 9.6 49.2 -8.3 315 1.6
11000 -1.2 29.8 300 12 6 8.0 4.4 9.5 49.1 -8.4 288 1.5
10750 -0.7 30.7 300 11 6 7.0 3.8 9.3 48.7 -8.6 265 1.3
10500 -0.2 31.6 300 11 6 6.5 3.5 9.1 48.3 -8.9 243 1.2
10250 0.3 32.5 300 11 5 9.7 5.3 8.9 48.0 -9.1 219 1.1
10000 1.2 34.2 305 11 5 10.0 5.5 9.0 48.2 -9.1 187 1.0
9750 1.7 35.1 305 11 6 7.0 3.8 8.8 47.9 -9.2 163 0.8
9500 2.2 36.0 305 11 6 7.1 3.9 8.6 47.6 -9.5 140 0.7
9250 2.8 37.0 305 11 6 8.0 4.4 8.5 47.2 -9.7 117 0.6
9000 3.4 38.1 305 11 6 7.5 4.1 8.3 47.0 -9.9 92 0.5
8750 3.8 38.8 305 11 6 5.8 3.2 8.1 46.5 -10.2 71 0.4
8500 4.2 39.6 300 11 6 7.2 3.9 7.8 46.1 -10.5 51 0.3
8250 4.7 40.5 300 11 6 3.5 1.9 7.6 45.6 -10.8 30 0.2
8000 4.3 39.7 300 11 6 -18.5 -10.1 6.4 43.6 -12.0 35 0.2
7750 1.8 35.2 290 9 4 -43.7 -24.0 3.2 37.8 -15.2 100 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 * * * * * *
04/29/2024 at 0900 MDT | 04/29/2024 at 1200 MDT
|
CAPE... +11.7 LI... +2.1 | CAPE... +68.2 LI... +0.7
CINH... -12.0 K Index... +0.2 | CINH... -1.3 K Index... +0.7
|
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 -56.3 -69.3 270 26 14 0.4 0.2 | -57.0 -70.6 265 28 14 0.4 0.2
45000 -55.7 -68.3 290 33 17 -1.4 -0.7 | -56.5 -69.7 280 34 17 -1.3 -0.7
40000 -58.2 -72.8 305 49 25 -1.6 -0.9 | -58.5 -73.3 295 46 24 -1.4 -0.7
38000 -57.2 -71.0 310 51 26 4.4 2.4 | -57.2 -71.0 300 48 25 5.0 2.7
36000 -54.2 -65.6 310 50 26 4.4 2.4 | -53.8 -64.8 300 47 24 5.0 2.7
34000 -51.1 -60.0 310 49 25 7.4 4.0 | -50.3 -58.5 300 46 24 7.9 4.3
32000 -46.6 -51.9 310 46 24 7.4 4.1 | -45.6 -50.1 300 45 23 7.9 4.3
30000 -42.1 -43.8 310 43 22 7.8 4.3 | -40.9 -41.6 300 43 22 7.7 4.2
29000 -39.8 -39.6 305 42 22 7.8 4.3 | -38.6 -37.5 295 42 22 7.7 4.2
28000 -37.4 -35.3 305 41 21 7.8 4.3 | -36.3 -33.3 295 41 21 7.7 4.2
27000 -35.1 -31.2 305 39 20 7.6 4.1 | -34.0 -29.2 295 39 20 7.6 4.1
26000 -32.9 -27.2 300 37 19 7.4 4.1 | -31.8 -25.2 290 37 19 7.5 4.1
25000 -30.7 -23.3 295 35 18 7.4 4.1 | -29.5 -21.1 290 34 18 7.5 4.1
24000 -28.5 -19.3 290 33 17 7.4 4.1 | -27.3 -17.1 285 32 16 7.7 4.2
23000 -26.2 -15.2 285 31 16 7.5 4.1 | -24.9 -12.8 285 31 16 7.9 4.3
22000 -24.0 -11.2 285 30 15 7.5 4.1 | -22.0 -7.6 280 29 15 7.9 4.3
21000 -21.3 -6.3 280 28 14 6.3 3.4 | -19.9 -3.8 280 29 15 4.9 2.7
20000 -19.3 -2.7 280 26 13 6.4 3.5 | -18.3 -0.9 275 27 14 5.2 2.8
19500 -18.4 -1.1 285 25 13 6.4 3.5 | -17.5 0.5 275 27 14 5.2 2.8
19000 -17.4 0.7 285 23 12 6.4 3.5 | -16.7 1.9 275 26 14 5.0 2.8
18500 -16.5 2.3 285 22 11 6.1 3.3 | -15.9 3.4 270 26 13 6.6 3.6
18000 -15.6 3.9 285 20 10 6.1 3.3 | -14.9 5.2 270 25 13 6.5 3.6
17500 -14.7 5.5 280 18 9 6.2 3.4 | -13.9 7.0 265 24 12 5.6 3.1
17000 -13.8 7.2 285 17 9 6.3 3.4 | -13.3 8.1 265 23 12 4.3 2.4
16500 -12.9 8.8 285 17 9 6.4 3.5 | -12.7 9.1 265 23 12 4.4 2.4
16000 -12.0 10.4 290 17 9 6.0 3.3 | -12.0 10.4 265 22 11 5.1 2.8
15500 -11.1 12.0 290 17 9 6.1 3.3 | -11.3 11.7 270 21 11 5.0 2.8
15000 -10.2 13.6 295 17 9 6.8 3.7 | -10.5 13.1 270 19 10 7.5 4.1
14500 -9.2 15.4 295 17 9 6.9 3.8 | -9.4 15.1 270 19 10 7.9 4.3
14000 -8.2 17.2 295 18 9 7.3 4.0 | -8.2 17.2 270 17 9 8.4 4.6
13500 -7.2 19.0 295 17 9 7.6 4.2 | -7.0 19.4 265 15 8 8.8 4.8
13000 -6.1 21.0 300 17 9 8.7 4.8 | -5.7 21.7 265 13 7 10.8 5.9
12500 -4.9 23.2 300 16 8 6.3 3.5 | -4.2 24.4 260 11 6 7.7 4.2
12000 -4.0 24.8 295 15 8 7.1 3.9 | -3.0 26.6 255 9 5 8.5 4.7
11750 -3.4 25.9 295 14 7 8.8 4.8 | -2.4 27.7 255 8 4 9.4 5.2
11500 -2.7 27.1 295 13 7 8.5 4.7 | -1.7 28.9 250 7 4 9.1 5.0
11250 -2.1 28.2 295 12 6 8.5 4.7 | -1.0 30.2 245 7 3 9.0 4.9
11000 -1.5 29.3 295 11 6 8.0 4.4 | -0.3 31.5 240 6 3 8.8 4.8
10750 -0.9 30.4 295 11 5 7.4 4.1 | 0.3 32.5 235 6 3 8.5 4.7
10500 -0.4 31.3 300 10 5 7.2 3.9 | 0.9 33.6 230 5 3 8.5 4.7
10250 0.2 32.4 300 9 5 9.3 5.1 | 1.6 34.9 220 5 3 11.0 6.0
10000 0.9 33.6 300 9 5 9.1 5.0 | 2.5 36.5 215 5 3 11.0 6.1
9750 1.5 34.7 300 8 4 7.1 3.9 | 3.2 37.8 215 5 3 9.3 5.1
9500 2.0 35.6 305 8 4 7.1 3.9 | 3.9 39.0 210 5 2 9.3 5.1
9250 2.6 36.7 305 8 4 8.8 4.8 | 4.6 40.3 210 5 2 10.7 5.9
9000 3.3 37.9 305 7 3 9.3 5.1 | 5.5 41.9 205 5 2 10.9 6.0
8750 3.9 39.0 305 7 3 7.7 4.2 | 6.2 43.2 200 5 2 9.6 5.3
8500 4.5 40.1 305 6 3 8.2 4.5 | 6.9 44.4 195 5 2 9.7 5.3
8250 5.1 41.2 305 6 3 8.0 4.4 | 7.7 45.9 195 4 2 10.7 5.9
8000 5.7 42.3 305 6 3 11.1 6.1 | 8.6 47.5 195 4 2 15.2 8.4
7750 6.6 43.9 300 5 3 16.1 8.9 | 9.9 49.8 190 4 2 19.2 10.5
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
04/29/2024 at 1500 MDT | 04/29/2024 at 1800 MDT
|
CAPE... +84.4 LI... -0.3 | CAPE... +153.8 LI... -2.4
CINH... -11.8 K Index... +8.9 | CINH... -11.4 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 -58.1 -72.6 260 31 16 -0.0 -0.0 | -59.3 -74.7 270 35 18 -0.1 -0.1
45000 -58.2 -72.8 275 35 18 -1.3 -0.7 | -59.4 -74.9 280 42 22 0.0 0.0
40000 -60.0 -76.0 295 48 25 -1.2 -0.7 | -59.4 -74.9 285 54 28 -0.0 -0.0
38000 -57.9 -72.2 295 50 26 6.5 3.6 | -57.0 -70.6 285 55 28 6.2 3.4
36000 -53.5 -64.3 295 48 25 6.5 3.6 | -52.9 -63.2 280 54 28 6.2 3.4
34000 -49.2 -56.6 290 47 24 7.9 4.4 | -48.7 -55.7 280 53 27 7.9 4.3
32000 -44.5 -48.1 290 45 23 7.9 4.4 | -44.0 -47.2 275 52 27 7.9 4.3
30000 -39.7 -39.5 290 44 23 8.3 4.5 | -39.2 -38.6 275 50 26 8.0 4.4
29000 -37.2 -35.0 290 43 22 8.3 4.5 | -36.8 -34.2 275 48 25 8.0 4.4
28000 -34.7 -30.5 290 42 22 8.3 4.5 | -34.4 -29.9 275 46 24 8.0 4.4
27000 -32.3 -26.1 290 41 21 7.7 4.2 | -32.1 -25.8 275 45 23 7.8 4.3
26000 -30.0 -22.0 290 39 20 7.7 4.2 | -29.7 -21.5 275 43 22 7.8 4.3
25000 -27.7 -17.9 285 38 19 7.7 4.2 | -27.4 -17.3 280 40 21 7.8 4.3
24000 -25.4 -13.7 285 36 18 7.4 4.1 | -25.1 -13.2 280 38 20 7.8 4.3
23000 -23.2 -9.8 280 33 17 7.1 3.9 | -22.7 -8.9 280 36 18 7.9 4.3
22000 -21.1 -6.0 270 31 16 7.1 3.9 | -20.4 -4.7 275 33 17 7.9 4.3
21000 -18.7 -1.7 265 29 15 4.4 2.4 | -18.3 -0.9 270 31 16 3.1 1.7
20000 -17.4 0.7 265 29 15 4.6 2.5 | -17.5 0.5 275 31 16 2.2 1.2
19500 -16.7 1.9 265 28 15 4.6 2.5 | -17.2 1.0 275 31 16 2.2 1.2
19000 -16.1 3.0 265 28 14 4.5 2.5 | -16.9 1.6 275 31 16 1.6 0.9
18500 -15.3 4.5 265 28 14 6.2 3.4 | -16.2 2.8 275 30 16 8.0 4.4
18000 -14.3 6.3 270 27 14 6.1 3.4 | -15.1 4.8 275 30 15 7.5 4.1
17500 -13.4 7.9 270 27 14 5.6 3.1 | -14.0 6.8 270 29 15 8.1 4.4
17000 -12.7 9.1 270 27 14 5.1 2.8 | -12.8 9.0 270 28 14 8.5 4.7
16500 -12.0 10.4 270 27 14 5.3 2.9 | -11.5 11.3 265 27 14 8.6 4.7
16000 -11.1 12.0 270 25 13 7.2 3.9 | -10.3 13.5 260 25 13 8.7 4.8
15500 -10.1 13.8 270 23 12 7.0 3.8 | -9.0 15.8 260 23 12 8.6 4.7
15000 -9.0 15.8 270 20 10 8.8 4.8 | -7.7 18.1 260 21 11 9.5 5.2
14500 -7.7 18.1 270 18 9 8.9 4.9 | -6.3 20.7 260 20 10 9.5 5.2
14000 -6.4 20.5 270 16 8 9.3 5.1 | -4.9 23.2 260 19 10 9.7 5.3
13500 -5.0 23.0 270 15 8 9.6 5.3 | -3.5 25.7 260 18 9 9.8 5.4
13000 -3.6 25.5 270 14 7 11.1 6.1 | -2.0 28.4 260 17 9 10.9 6.0
12500 -2.1 28.2 265 13 7 7.9 4.3 | -0.5 31.1 255 16 8 8.3 4.5
12000 -0.8 30.6 270 11 6 8.1 4.4 | 0.8 33.4 255 15 8 8.6 4.7
11750 -0.2 31.6 265 11 6 7.4 4.1 | 1.4 34.5 255 15 8 8.6 4.7
11500 0.3 32.5 260 10 5 8.7 4.8 | 2.1 35.8 250 14 7 9.3 5.1
11250 1.1 34.0 255 10 5 10.3 5.7 | 2.8 37.0 250 14 7 10.1 5.6
11000 1.8 35.2 255 9 5 8.7 4.8 | 3.5 38.3 250 13 7 8.9 4.9
10750 2.3 36.1 250 9 5 6.9 3.8 | 4.1 39.4 245 13 7 7.4 4.0
10500 2.9 37.2 245 8 4 7.0 3.8 | 4.7 40.5 245 12 6 7.8 4.3
10250 3.4 38.1 235 8 4 9.8 5.4 | 5.3 41.5 240 12 6 10.8 5.9
10000 4.2 39.6 230 8 4 9.6 5.3 | 6.2 43.2 240 11 6 10.2 5.6
9750 4.8 40.6 225 8 4 7.4 4.1 | 6.8 44.2 235 11 5 7.7 4.2
9500 5.3 41.5 220 8 4 7.1 3.9 | 7.4 45.3 230 10 5 7.1 3.9
9250 5.9 42.6 215 8 4 9.4 5.1 | 7.9 46.2 225 10 5 9.9 5.4
9000 6.6 43.9 205 8 4 10.4 5.7 | 8.8 47.8 220 10 5 10.7 5.9
8750 7.3 45.1 200 8 4 8.8 4.8 | 9.4 48.9 215 9 5 8.3 4.5
8500 8.0 46.4 195 8 4 9.2 5.0 | 10.1 50.2 210 9 4 9.1 5.0
8250 8.7 47.7 190 8 4 9.4 5.2 | 10.7 51.3 205 8 4 7.9 4.3
8000 9.4 48.9 185 8 4 13.1 7.2 | 11.2 52.2 200 8 4 8.2 4.5
7750 10.6 51.1 185 7 4 17.9 9.8 | 11.9 53.4 195 7 3 11.6 6.4
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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