Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
285
UXUS97 KPUB 181219
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0619 MDT Saturday, May 18, 2024
This forecast is for the Air Force Academy for Saturday, May 18, 2024:
If the trigger temperature of 62.7 F/17.0 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1055 ft/min (5.4 m/s)
Maximum height of thermals.................. 20414 ft MSL (12801 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ 1300 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................. 16683 ft MSL (9070 ft AGL)
Thermal soaring outlook for Sunday 05/19....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:43:18 / 20:08:14 MDT
Total possible sunshine........... 14 hr 24 min 56 sec (864 min 56 sec)
Altitude of sun at 12:55:46 MDT... 70.78 degrees
Upper air data from numerical model forecast valid on 05/18/2024 at 0600 MDT
Freezing level.................. 13468 ft MSL (5855 ft AGL)
Convective condensation level... 16779 ft MSL (9166 ft AGL)
Lifted condensation level....... 18126 ft MSL (10513 ft AGL)
Lifted index.................... -1.4
K index......................... +13.3
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 -59.0 -74.2 255 31 16 1.2 0.6 M M M M M
45000 -57.4 -71.3 255 32 17 0.4 0.2 M M M M M
40000 -56.8 -70.2 250 40 21 -0.4 -0.2 M M M M M
38000 -53.7 -64.7 255 43 22 5.9 3.2 M M M M M
36000 -50.2 -58.4 255 46 23 5.9 3.3 M M M M M
34000 -46.4 -51.5 260 47 24 6.8 3.7 M M M M M
32000 -41.8 -43.2 260 45 23 6.8 3.7 M M M M M
30000 -37.3 -35.1 265 42 22 8.2 4.5 31.0 87.8 6.8 M M
29000 -34.8 -30.6 265 40 20 8.2 4.5 30.4 86.7 6.4 M M
28000 -32.4 -26.3 260 37 19 8.1 4.5 29.9 85.8 6.1 M M
27000 -30.1 -22.2 260 35 18 7.3 4.0 29.1 84.4 5.5 M M
26000 -27.9 -18.2 260 32 16 7.2 4.0 28.1 82.6 4.8 M M
25000 -25.8 -14.4 255 29 15 7.2 4.0 27.2 81.0 4.1 M M
24000 -23.6 -10.5 255 26 13 6.8 3.7 26.3 79.4 3.4 M M
23000 -21.6 -6.9 260 23 12 6.9 3.8 25.2 77.4 2.5 M M
22000 -19.5 -3.1 265 20 10 6.9 3.8 24.2 75.6 1.7 M M
21000 -17.6 0.3 270 19 10 6.1 3.4 23.1 73.7 0.8 M M
20000 -15.3 4.5 275 20 10 6.2 3.4 21.6 70.8 -0.6 1209 6.1
19500 -14.4 6.1 275 21 11 6.3 3.4 21.0 69.8 -1.1 1167 5.9
19000 -13.4 7.9 275 21 11 7.0 3.8 20.5 68.8 -1.6 1125 5.7
18500 -12.4 9.7 275 22 11 7.5 4.1 20.1 68.1 -2.0 1077 5.5
18000 -11.3 11.7 275 23 12 7.6 4.2 19.7 67.5 -2.4 1030 5.2
17500 -10.1 13.8 275 24 12 8.7 4.8 19.5 67.0 -2.7 980 5.0
17000 -8.8 16.2 280 24 12 8.7 4.8 19.3 66.7 -2.9 927 4.7
16500 -7.6 18.3 280 23 12 8.3 4.6 19.1 66.4 -3.1 875 4.4
16000 -6.4 20.5 285 23 12 8.3 4.5 18.8 65.9 -3.4 825 4.2
15500 -5.2 22.6 285 22 11 8.5 4.7 18.6 65.5 -3.7 775 3.9
15000 -3.9 25.0 290 20 10 9.1 5.0 18.4 65.2 -3.9 722 3.7
14500 -2.6 27.3 295 19 10 9.1 5.0 18.3 65.0 -4.1 668 3.4
14000 -1.3 29.7 295 17 9 8.6 4.7 18.2 64.8 -4.3 615 3.1
13500 -0.1 31.8 300 14 7 8.4 4.6 18.0 64.4 -4.5 562 2.9
13000 1.3 34.3 305 11 6 11.0 6.0 18.0 64.4 -4.6 505 2.6
12500 2.7 36.9 315 9 5 8.1 4.4 17.9 64.3 -4.7 449 2.3
12000 4.0 39.2 320 8 4 8.9 4.9 17.8 64.0 -4.9 396 2.0
11750 4.6 40.3 325 8 4 9.1 5.0 17.7 63.9 -5.0 369 1.9
11500 5.4 41.7 325 8 4 10.5 5.8 17.7 63.9 -5.0 340 1.7
11250 6.2 43.2 330 8 4 10.7 5.9 17.8 64.0 -4.9 308 1.6
11000 6.9 44.4 335 8 4 8.7 4.8 17.8 64.0 -4.9 279 1.4
10750 7.5 45.5 340 8 4 7.7 4.2 17.6 63.8 -5.1 254 1.3
10500 8.1 46.6 340 8 4 8.7 4.8 17.5 63.5 -5.2 229 1.2
10250 8.8 47.8 345 8 4 10.2 5.6 17.5 63.5 -5.3 200 1.0
10000 9.5 49.1 350 8 4 9.6 5.3 17.5 63.6 -5.3 170 0.9
9750 10.2 50.4 350 9 5 8.8 4.8 17.5 63.4 -5.3 143 0.7
9500 10.9 51.6 350 9 5 8.9 4.9 17.4 63.3 -5.4 116 0.6
9250 11.5 52.7 355 9 5 9.3 5.1 17.4 63.2 -5.5 89 0.5
9000 12.2 54.0 355 9 5 8.6 4.7 17.3 63.2 -5.5 61 0.3
8750 12.8 55.0 350 9 5 7.3 4.0 17.2 62.9 -5.7 36 0.2
8500 13.4 56.1 350 9 5 9.0 4.9 17.0 62.6 -5.9 11 0.1
8250 13.9 57.0 345 9 5 3.5 1.9 16.9 62.4 -6.0 M M
8000 13.5 56.3 335 8 4 -18.9 -10.4 15.7 60.2 -7.2 M M
7750 11.2 52.2 315 7 3 -39.5 -21.7 12.6 54.7 -10.3 55 0.3
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 * * * * * *
05/18/2024 at 0900 MDT | 05/18/2024 at 1200 MDT
|
CAPE... +76.7 LI... -1.4 | CAPE... +346.4 LI... -1.9
CINH... -37.7 K Index... +17.1 | CINH... -10.3 K Index... +26.4
|
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 -59.1 -74.4 255 31 16 1.1 0.6 | -58.1 -72.6 250 35 18 1.4 0.8
45000 -57.6 -71.7 245 31 16 -0.1 -0.1 | -56.5 -69.7 240 42 22 -1.2 -0.7
40000 -57.8 -72.0 250 39 20 -0.9 -0.5 | -58.4 -73.1 235 47 24 -2.0 -1.1
38000 -54.5 -66.1 255 41 21 6.3 3.5 | -55.2 -67.4 235 45 23 6.4 3.5
36000 -50.7 -59.3 255 42 22 6.3 3.5 | -51.3 -60.3 245 43 22 6.4 3.5
34000 -46.3 -51.3 260 42 22 6.7 3.7 | -46.8 -52.2 250 41 21 6.9 3.8
32000 -42.2 -44.0 265 41 21 6.7 3.7 | -42.7 -44.9 250 39 20 6.9 3.8
30000 -37.7 -35.9 265 40 21 8.3 4.5 | -38.1 -36.6 255 38 20 8.2 4.5
29000 -35.2 -31.4 265 40 21 8.3 4.5 | -35.7 -32.3 260 38 20 8.2 4.5
28000 -32.7 -26.9 265 40 20 8.3 4.5 | -33.2 -27.8 260 38 20 8.2 4.5
27000 -30.4 -22.7 265 39 20 7.7 4.2 | -30.8 -23.4 265 38 20 7.9 4.4
26000 -28.1 -18.6 265 37 19 7.6 4.2 | -28.5 -19.3 265 39 20 8.0 4.4
25000 -25.8 -14.4 260 36 19 7.6 4.2 | -26.1 -15.0 265 39 20 8.0 4.4
24000 -23.6 -10.5 260 34 17 6.8 3.7 | -24.0 -11.2 265 39 20 5.8 3.2
23000 -21.6 -6.9 260 30 16 6.8 3.7 | -22.2 -8.0 270 38 19 5.9 3.2
22000 -19.5 -3.1 260 27 14 6.8 3.7 | -20.5 -4.9 270 36 19 6.0 3.3
21000 -17.7 0.1 265 25 13 5.5 3.0 | -18.4 -1.1 270 35 18 8.3 4.6
20000 -15.7 3.7 270 27 14 5.5 3.0 | -15.4 4.3 270 32 17 8.4 4.6
19500 -14.9 5.2 275 28 14 5.5 3.0 | -14.2 6.4 270 31 16 8.4 4.6
19000 -14.0 6.8 275 29 15 6.9 3.8 | -12.9 8.8 270 30 16 8.4 4.6
18500 -12.9 8.8 275 28 15 7.5 4.1 | -11.7 10.9 265 28 14 8.4 4.6
18000 -11.8 10.8 275 28 15 7.7 4.2 | -10.5 13.1 265 25 13 8.4 4.6
17500 -10.6 12.9 275 28 14 9.5 5.2 | -9.3 15.3 260 23 12 7.9 4.3
17000 -9.2 15.4 275 27 14 9.4 5.2 | -8.1 17.4 255 20 10 8.0 4.4
16500 -7.8 18.0 275 27 14 9.4 5.1 | -7.0 19.4 250 18 9 7.9 4.4
16000 -6.5 20.3 270 26 14 9.3 5.1 | -5.8 21.6 245 16 8 8.0 4.4
15500 -5.1 22.8 270 26 13 9.2 5.1 | -4.7 23.5 235 15 8 8.3 4.5
15000 -3.7 25.3 270 24 13 9.1 5.0 | -3.4 25.9 230 14 7 8.6 4.7
14500 -2.4 27.7 265 23 12 9.1 5.0 | -2.1 28.2 225 14 7 8.6 4.7
14000 -1.1 30.0 260 21 11 9.1 5.0 | -0.8 30.6 215 14 7 8.6 4.7
13500 0.2 32.4 255 18 9 9.2 5.0 | 0.5 32.9 210 14 7 8.7 4.7
13000 1.6 34.9 245 16 8 9.3 5.1 | 1.7 35.1 205 15 8 8.2 4.5
12500 2.8 37.0 235 13 7 7.7 4.2 | 2.9 37.2 200 15 8 7.6 4.2
12000 3.9 39.0 230 11 5 8.0 4.4 | 4.0 39.2 190 14 7 7.5 4.1
11750 4.5 40.1 230 10 5 8.0 4.4 | 4.6 40.3 185 14 7 7.7 4.2
11500 5.2 41.4 225 9 5 9.0 5.0 | 5.2 41.4 180 14 7 9.9 5.4
11250 5.9 42.6 220 9 4 8.7 4.8 | 5.9 42.6 175 13 7 10.3 5.6
11000 6.4 43.5 215 8 4 7.1 3.9 | 6.6 43.9 170 13 7 8.8 4.8
10750 6.9 44.4 215 7 3 6.7 3.7 | 7.3 45.1 170 13 7 8.5 4.7
10500 7.5 45.5 210 5 3 7.5 4.1 | 7.9 46.2 165 13 6 9.7 5.3
10250 8.1 46.6 200 4 2 8.8 4.8 | 8.7 47.7 160 13 7 11.1 6.1
10000 8.7 47.7 195 3 2 8.5 4.7 | 9.5 49.1 160 13 7 10.3 5.7
9750 9.3 48.7 180 2 1 8.1 4.4 | 10.2 50.4 160 13 7 9.8 5.4
9500 9.9 49.8 125 1 0 8.5 4.7 | 11.0 51.8 160 13 7 10.4 5.7
9250 10.5 50.9 060 2 1 7.3 4.0 | 11.7 53.1 155 13 7 8.6 4.7
9000 11.0 51.8 045 3 1 8.7 4.8 | 12.3 54.1 155 13 7 9.2 5.1
8750 11.8 53.2 045 4 2 10.9 6.0 | 13.2 55.8 155 13 7 11.5 6.3
8500 12.6 54.7 040 4 2 10.4 5.7 | 14.0 57.2 155 13 7 10.7 5.9
8250 13.3 55.9 040 5 3 10.0 5.5 | 14.8 58.6 155 13 7 11.6 6.4
8000 14.1 57.4 040 5 3 12.9 7.1 | 15.8 60.4 155 13 6 17.5 9.6
7750 15.3 59.5 040 6 3 19.2 10.5 | 17.4 63.3 150 12 6 25.1 13.8
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
05/18/2024 at 1500 MDT | 05/18/2024 at 1800 MDT
|
CAPE... +274.3 LI... -1.4 | CAPE... +566.6 LI... -1.6
CINH... -6.5 K Index... +27.2 | CINH... -27.6 K Index... +25.3
|
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 -57.6 -71.7 250 38 20 1.0 0.6 | -57.2 -71.0 250 42 22 1.6 0.9
45000 -56.7 -70.1 245 44 23 -1.8 -1.0 | -55.8 -68.4 250 47 24 -3.3 -1.8
40000 -59.5 -75.1 235 47 24 -2.5 -1.3 | -60.7 -77.3 240 43 22 -3.8 -2.1
38000 -56.5 -69.7 235 46 23 6.2 3.4 | -57.3 -71.1 235 37 19 6.6 3.6
36000 -52.3 -62.1 245 44 22 6.2 3.4 | -53.4 -64.1 230 31 16 6.6 3.6
34000 -48.0 -54.4 250 40 21 7.8 4.3 | -48.4 -55.1 225 29 15 9.4 5.1
32000 -43.3 -45.9 265 37 19 7.8 4.3 | -42.8 -45.0 225 29 15 9.4 5.1
30000 -38.4 -37.1 270 35 18 8.6 4.7 | -37.4 -35.3 225 29 15 8.8 4.8
29000 -35.8 -32.4 275 34 18 8.6 4.7 | -34.8 -30.6 225 29 15 8.8 4.8
28000 -33.2 -27.8 275 33 17 8.7 4.8 | -32.2 -26.0 225 29 15 8.8 4.8
27000 -30.7 -23.3 275 33 17 8.5 4.6 | -29.8 -21.6 220 29 15 7.7 4.2
26000 -28.2 -18.8 270 33 17 8.5 4.7 | -27.5 -17.5 220 30 15 7.6 4.2
25000 -25.6 -14.1 270 33 17 8.5 4.7 | -25.3 -13.5 220 31 16 7.6 4.2
24000 -23.3 -9.9 265 33 17 7.4 4.1 | -23.0 -9.4 220 31 16 7.1 3.9
23000 -21.1 -6.0 260 33 17 7.5 4.1 | -20.4 -4.7 220 32 16 7.2 3.9
22000 -18.3 -0.9 255 33 17 7.6 4.2 | -18.3 -0.9 220 32 17 7.2 4.0
21000 -16.3 2.7 245 33 17 6.9 3.8 | -16.2 2.8 220 33 17 7.1 3.9
20000 -14.2 6.4 240 34 17 6.9 3.8 | -14.1 6.6 220 33 17 7.1 3.9
19500 -13.2 8.2 235 34 18 6.9 3.8 | -13.0 8.6 220 33 17 7.2 3.9
19000 -12.2 10.0 235 35 18 6.8 3.7 | -12.0 10.4 220 33 17 7.7 4.2
18500 -11.3 11.7 230 34 18 6.7 3.7 | -10.8 12.6 220 32 17 8.0 4.4
18000 -10.3 13.5 225 34 17 6.8 3.7 | -9.6 14.7 220 32 16 8.0 4.4
17500 -9.2 15.4 225 33 17 8.4 4.6 | -8.5 16.7 220 32 16 7.5 4.1
17000 -8.0 17.6 220 32 16 8.3 4.6 | -7.4 18.7 225 31 16 7.6 4.2
16500 -6.8 19.8 220 30 16 7.8 4.3 | -6.4 20.5 225 31 16 6.9 3.8
16000 -5.7 21.7 215 28 15 7.7 4.2 | -5.4 22.3 225 30 15 6.8 3.7
15500 -4.6 23.7 210 27 14 7.7 4.2 | -4.4 24.1 225 29 15 6.9 3.8
15000 -3.4 25.9 205 25 13 7.8 4.3 | -3.4 25.9 225 28 14 7.1 3.9
14500 -2.3 27.9 200 24 12 7.8 4.3 | -2.4 27.7 225 27 14 7.1 3.9
14000 -1.1 30.0 195 23 12 8.6 4.7 | -1.4 29.5 225 26 13 6.3 3.5
13500 0.2 32.4 195 22 12 8.3 4.6 | -0.5 31.1 225 25 13 6.4 3.5
13000 1.6 34.9 195 22 11 10.3 5.6 | 0.4 32.7 220 24 12 7.0 3.9
12500 2.9 37.2 190 21 11 8.5 4.7 | 1.4 34.5 220 23 12 5.6 3.0
12000 4.3 39.7 190 21 11 9.2 5.0 | 2.3 36.1 220 21 11 7.1 3.9
11750 4.9 40.8 190 20 11 9.3 5.1 | 2.8 37.0 220 21 11 7.1 3.9
11500 5.7 42.3 190 20 10 10.2 5.6 | 3.3 37.9 215 20 10 7.5 4.1
11250 6.4 43.5 190 20 10 10.1 5.6 | 3.9 39.0 215 19 10 7.4 4.1
11000 7.1 44.8 190 19 10 9.3 5.1 | 4.4 39.9 215 19 10 6.5 3.6
10750 7.8 46.0 190 19 10 8.9 4.9 | 4.9 40.8 210 18 9 6.2 3.4
10500 8.5 47.3 190 19 10 9.8 5.4 | 5.3 41.5 210 18 9 6.8 3.8
10250 9.3 48.7 190 18 9 10.6 5.8 | 5.9 42.6 205 17 9 7.7 4.2
10000 10.0 50.0 190 17 9 9.6 5.3 | 6.4 43.5 205 16 8 6.4 3.5
9750 10.7 51.3 190 17 9 9.2 5.0 | 6.7 44.1 200 16 8 5.4 3.0
9500 11.4 52.5 190 16 8 9.0 4.9 | 7.1 44.8 200 16 8 5.6 3.1
9250 12.1 53.8 190 16 8 10.3 5.6 | 7.5 45.5 200 15 8 5.8 3.2
9000 12.9 55.2 190 14 7 10.5 5.8 | 8.2 46.8 200 14 7 4.8 2.6
8750 13.6 56.5 190 14 7 9.4 5.2 | 8.6 47.5 200 14 7 5.3 2.9
8500 14.3 57.7 195 13 7 9.5 5.2 | 8.9 48.0 200 13 7 4.0 2.2
8250 15.0 59.0 195 12 6 10.4 5.7 | 9.1 48.4 205 11 6 6.1 3.4
8000 15.9 60.6 195 11 5 12.1 6.6 | 9.8 49.6 200 7 4 13.4 7.4
7750 16.7 62.1 200 8 4 12.0 6.6 | 10.5 50.9 200 4 2 -0.5 -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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