Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
760
UXUS97 KPUB 101222
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0622 MDT Monday, June 10, 2024
This forecast is for the Air Force Academy for Monday, June 10, 2024:
If the trigger temperature of 69.3 F/20.7 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 497 ft/min (2.5 m/s)
Maximum height of thermals.................. 15292 ft MSL (7680 ft AGL)
Forecast maximum temperature................... 75.0 F/24.3 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 11644 ft MSL (4032 ft AGL)
Thermal soaring outlook for Tuesday 06/11...... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:33:13 / 20:24:37 MDT
Total possible sunshine........... 14 hr 51 min 25 sec (891 min 25 sec)
Altitude of sun at 12:58:55 MDT... 74.11 degrees
Upper air data from numerical model forecast valid on 06/10/2024 at 0600 MDT
Freezing level.................. 15634 ft MSL (8022 ft AGL)
Convective condensation level... 14091 ft MSL (6479 ft AGL)
Lifted condensation level....... 14489 ft MSL (6877 ft AGL)
Lifted index.................... -4.5
K index......................... +25.5
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 -57.2 -71.0 285 3 2 4.4 2.4 M M M M M
45000 -53.4 -64.1 215 17 9 -2.7 -1.5 M M M M M
40000 -56.2 -69.2 210 54 28 8.3 4.6 M M M M M
38000 -51.6 -60.9 215 39 20 7.7 4.2 M M M M M
36000 -47.0 -52.6 215 25 13 7.7 4.2 M M M M M
34000 -41.7 -43.1 205 15 8 9.1 5.0 M M M M M
32000 -35.6 -32.1 165 7 4 9.0 4.9 M M M M M
30000 -30.8 -23.4 140 6 3 8.0 4.4 37.9 100.2 10.9 M M
29000 -28.4 -19.1 135 5 3 8.0 4.4 37.3 99.1 10.5 M M
28000 -26.1 -15.0 130 5 3 7.6 4.2 36.7 98.1 10.1 M M
27000 -23.9 -11.0 120 6 3 7.2 3.9 35.7 96.2 9.4 M M
26000 -21.8 -7.2 110 6 3 7.2 3.9 34.7 94.4 8.6 M M
25000 -19.7 -3.5 105 7 4 7.4 4.0 33.8 92.9 8.0 M M
24000 -17.9 -0.2 090 7 3 5.8 3.2 32.5 90.5 7.0 M M
23000 -16.2 2.8 060 7 3 5.8 3.2 31.1 88.0 5.8 M M
22000 -14.5 5.9 040 8 4 5.7 3.1 29.8 85.6 4.7 M M
21000 -12.6 9.3 025 10 5 6.8 3.7 28.6 83.5 3.7 M M
20000 -10.1 13.8 015 15 7 6.8 3.7 27.3 81.2 2.6 M M
19500 -9.1 15.6 010 16 8 6.8 3.7 26.9 80.4 2.1 M M
19000 -8.1 17.4 010 16 8 7.6 4.2 26.5 79.7 1.8 M M
18500 -7.0 19.4 015 15 8 7.5 4.1 26.1 79.0 1.4 M M
18000 -5.9 21.4 020 14 7 8.4 4.6 25.8 78.4 1.1 M M
17500 -4.5 23.9 020 13 7 9.0 4.9 25.6 78.1 1.0 M M
17000 -3.2 26.2 015 11 6 9.0 4.9 25.5 77.9 0.8 M M
16500 -2.0 28.4 015 10 5 8.0 4.4 25.3 77.5 0.6 M M
16000 -0.8 30.6 015 9 4 8.1 4.4 25.0 77.0 0.4 M M
15500 0.4 32.7 020 7 4 7.9 4.4 24.7 76.5 0.1 M M
15000 1.6 34.9 030 5 3 7.9 4.3 24.4 76.0 -0.2 664 3.4
14500 2.8 37.0 050 4 2 7.8 4.3 24.2 75.5 -0.5 614 3.1
14000 3.8 38.8 075 3 1 7.6 4.2 23.8 74.8 -0.8 567 2.9
13500 4.9 40.8 110 3 1 7.6 4.1 23.5 74.2 -1.2 520 2.6
13000 6.0 42.8 135 2 1 7.4 4.1 23.1 73.6 -1.6 473 2.4
12500 7.0 44.6 160 3 1 7.7 4.2 22.7 72.9 -2.0 427 2.2
12000 8.0 46.4 185 4 2 6.5 3.6 22.3 72.2 -2.6 384 2.0
11750 8.4 47.1 195 5 2 6.7 3.7 22.1 71.7 -2.9 364 1.8
11500 8.9 48.0 200 6 3 8.5 4.7 21.9 71.4 -3.1 342 1.7
11250 9.5 49.1 200 6 3 6.9 3.8 21.8 71.2 -3.2 316 1.6
11000 9.8 49.6 205 7 4 4.7 2.6 21.4 70.6 -3.6 299 1.5
10750 10.2 50.4 205 8 4 4.5 2.5 21.1 69.9 -4.0 281 1.4
10500 10.6 51.1 210 9 5 7.6 4.2 20.7 69.3 -4.4 263 1.3
10250 11.1 52.0 210 10 5 4.8 2.6 20.6 69.1 -4.5 237 1.2
10000 11.1 52.0 215 11 6 -1.0 -0.6 19.9 67.7 -5.3 231 1.2
9750 11.0 51.8 215 13 7 0.1 0.0 19.1 66.4 -6.1 226 1.1
9500 11.0 51.8 215 14 7 -0.1 -0.1 18.3 65.0 -6.9 221 1.1
9250 10.9 51.6 215 16 8 -0.6 -0.3 17.6 63.7 -7.8 216 1.1
9000 10.8 51.4 210 17 9 0.2 0.1 16.8 62.3 -8.6 211 1.1
8750 10.8 51.4 210 19 10 1.3 0.7 16.1 61.1 -9.3 203 1.0
8500 10.8 51.4 205 20 10 1.2 0.6 15.5 59.9 -10.1 195 1.0
8250 10.9 51.6 200 21 11 3.6 2.0 14.9 58.9 -10.7 185 0.9
8000 11.3 52.3 200 19 10 6.4 3.5 14.6 58.3 -11.1 167 0.8
7750 11.7 53.1 195 14 7 6.4 3.5 14.3 57.8 -11.4 146 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 * * * * * *
06/10/2024 at 0900 MDT | 06/10/2024 at 1200 MDT
|
CAPE... +1201.3 LI... -4.4 | CAPE... +2082.1 LI... -6.6
CINH... -59.3 K Index... +25.6 | CINH... -8.3 K Index... +25.7
|
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 -59.2 -74.6 220 8 4 3.4 1.9 | -59.5 -75.1 240 17 9 2.7 1.5
45000 -55.5 -67.9 220 21 11 -0.3 -0.1 | -56.1 -69.0 240 29 15 0.8 0.4
40000 -55.1 -67.2 230 43 22 6.9 3.8 | -54.3 -65.7 240 37 19 6.4 3.5
38000 -51.1 -60.0 225 33 17 6.7 3.7 | -50.5 -58.9 230 33 17 6.2 3.4
36000 -47.1 -52.8 215 25 13 6.6 3.6 | -46.8 -52.2 220 29 15 6.2 3.4
34000 -41.8 -43.2 215 19 10 9.4 5.1 | -41.7 -43.1 215 22 11 9.2 5.0
32000 -35.5 -31.9 210 15 8 9.3 5.1 | -35.5 -31.9 215 12 6 9.1 5.0
30000 -30.4 -22.7 195 11 6 8.4 4.6 | -30.4 -22.7 195 10 5 8.5 4.7
29000 -27.9 -18.2 180 10 5 8.4 4.6 | -27.9 -18.2 180 9 5 8.6 4.7
28000 -25.4 -13.7 165 9 5 7.2 4.0 | -25.3 -13.5 165 10 5 7.2 4.0
27000 -23.6 -10.5 155 11 5 6.1 3.3 | -23.6 -10.5 160 11 6 6.0 3.3
26000 -21.8 -7.2 145 13 7 6.1 3.3 | -21.8 -7.2 155 13 7 6.0 3.3
25000 -20.0 -4.0 140 15 8 6.0 3.3 | -20.0 -4.0 155 14 7 5.9 3.2
24000 -18.1 -0.6 130 13 7 6.6 3.6 | -18.1 -0.6 145 13 7 6.4 3.5
23000 -16.2 2.8 115 11 5 6.6 3.6 | -16.3 2.7 125 10 5 6.4 3.5
22000 -14.2 6.4 090 9 5 6.6 3.6 | -14.4 6.1 100 9 5 6.5 3.5
21000 -12.4 9.7 055 10 5 6.1 3.4 | -12.5 9.5 075 10 5 6.5 3.6
20000 -10.6 12.9 035 14 7 6.2 3.4 | -10.5 13.1 050 13 7 6.5 3.6
19500 -9.3 15.3 025 18 9 6.3 3.5 | -9.6 14.7 045 15 8 6.5 3.6
19000 -8.2 17.2 025 18 9 8.5 4.7 | -8.1 17.4 040 16 8 7.7 4.2
18500 -7.0 19.4 025 17 9 8.4 4.6 | -7.0 19.4 035 16 8 7.7 4.2
18000 -5.8 21.6 030 15 8 8.4 4.6 | -5.8 21.6 035 16 8 8.3 4.6
17500 -4.6 23.7 035 13 7 8.4 4.6 | -4.6 23.7 040 13 7 8.7 4.8
17000 -3.4 25.9 035 11 5 8.4 4.6 | -3.4 25.9 040 11 6 8.8 4.8
16500 -2.2 28.0 040 9 5 8.1 4.4 | -2.1 28.2 045 9 5 8.8 4.8
16000 -0.9 30.4 045 7 4 8.1 4.5 | -0.8 30.6 045 6 3 8.8 4.8
15500 0.3 32.5 050 6 3 8.2 4.5 | 0.5 32.9 055 4 2 8.3 4.6
15000 1.5 34.7 055 4 2 8.2 4.5 | 1.8 35.2 060 2 1 8.3 4.6
14500 2.7 36.9 070 3 1 8.3 4.5 | 3.0 37.4 090 1 1 8.5 4.6
14000 3.9 39.0 110 2 1 8.3 4.6 | 4.3 39.7 000 0 0 8.6 4.7
13500 5.1 41.2 145 3 1 8.2 4.5 | 5.5 41.9 235 1 0 8.8 4.8
13000 6.3 43.3 170 3 2 7.7 4.2 | 6.8 44.2 270 2 1 9.1 5.0
12500 7.5 45.5 180 4 2 8.8 4.8 | 8.0 46.4 275 3 1 8.2 4.5
12000 8.6 47.5 190 4 2 6.7 3.7 | 9.0 48.2 280 4 2 7.3 4.0
11750 9.0 48.2 200 4 2 7.0 3.8 | 9.5 49.1 280 4 2 7.6 4.1
11500 9.5 49.1 200 5 2 7.2 4.0 | 10.0 50.0 275 5 2 8.3 4.6
11250 10.0 50.0 200 5 3 7.1 3.9 | 10.6 51.1 270 5 2 7.0 3.9
11000 10.5 50.9 200 6 3 7.1 3.9 | 11.0 51.8 260 5 3 6.2 3.4
10750 11.0 51.8 200 7 3 6.2 3.4 | 11.4 52.5 250 6 3 5.1 2.8
10500 11.5 52.7 200 8 4 9.9 5.5 | 11.8 53.2 240 6 3 10.5 5.8
10250 12.3 54.1 200 8 4 8.7 4.8 | 12.7 54.9 235 6 3 10.3 5.7
10000 12.6 54.7 205 8 4 4.1 2.2 | 13.0 55.4 220 7 4 4.6 2.5
9750 12.9 55.2 210 8 4 5.2 2.9 | 13.4 56.1 210 8 4 6.5 3.6
9500 13.3 55.9 215 8 4 5.3 2.9 | 13.7 56.7 205 9 5 4.8 2.6
9250 13.6 56.5 215 8 4 3.4 1.9 | 13.9 57.0 195 10 5 4.7 2.6
9000 13.7 56.7 215 9 4 1.1 0.6 | 14.4 57.9 190 11 6 9.1 5.0
8750 13.6 56.5 220 9 5 1.3 0.7 | 15.2 59.4 185 11 6 11.1 6.1
8500 13.6 56.5 220 10 5 1.6 0.9 | 16.0 60.8 185 12 6 10.4 5.7
8250 13.7 56.7 220 10 5 5.8 3.2 | 16.7 62.1 180 12 6 11.7 6.4
8000 14.4 57.9 205 10 5 14.5 7.9 | 17.8 64.0 180 12 6 19.7 10.8
7750 15.7 60.3 200 9 5 20.6 11.3 | 19.7 67.5 175 11 6 29.6 16.2
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
06/10/2024 at 1500 MDT | 06/10/2024 at 1800 MDT
|
CAPE... +2239.6 LI... -6.6 | CAPE... +1720.3 LI... -5.0
CINH... -5.5 K Index... +23.7 | CINH... -12.0 K Index... +23.2
|
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 -59.0 -74.2 255 20 10 2.8 1.5 | -58.5 -73.3 270 18 9 2.5 1.4
45000 -56.0 -68.8 245 32 16 -0.3 -0.2 | -56.0 -68.8 260 27 14 -0.8 -0.5
40000 -55.6 -68.1 235 37 19 8.4 4.6 | -56.1 -69.0 250 22 11 8.9 4.9
38000 -50.7 -59.3 230 32 17 8.0 4.4 | -50.8 -59.4 240 19 10 8.7 4.8
36000 -45.9 -50.6 220 28 15 8.0 4.4 | -45.6 -50.1 225 16 8 8.7 4.8
34000 -40.3 -40.5 215 21 11 8.4 4.6 | -39.7 -39.5 225 11 6 8.6 4.7
32000 -35.2 -31.4 210 14 7 8.3 4.5 | -34.6 -30.3 230 7 3 8.5 4.7
30000 -30.4 -22.7 200 12 6 8.1 4.5 | -29.8 -21.6 235 5 3 7.9 4.4
29000 -28.0 -18.4 195 11 6 8.1 4.5 | -27.4 -17.3 240 5 2 8.0 4.4
28000 -25.6 -14.1 185 10 5 7.0 3.8 | -25.1 -13.2 240 4 2 7.2 3.9
27000 -23.9 -11.0 175 11 6 5.5 3.0 | -23.2 -9.8 215 7 4 6.3 3.5
26000 -22.3 -8.1 170 13 6 5.5 3.0 | -21.3 -6.3 205 10 5 6.3 3.5
25000 -20.6 -5.1 160 14 7 5.4 3.0 | -19.5 -3.1 200 13 7 6.4 3.5
24000 -18.8 -1.8 150 12 6 6.6 3.6 | -17.6 0.3 195 12 6 5.9 3.2
23000 -16.8 1.8 135 9 5 6.6 3.6 | -15.9 3.4 190 9 5 5.9 3.2
22000 -14.9 5.2 105 8 4 6.6 3.6 | -14.1 6.6 175 6 3 5.7 3.1
21000 -12.6 9.3 080 9 5 7.9 4.3 | -11.9 10.6 105 3 1 8.0 4.4
20000 -10.3 13.5 060 11 5 7.9 4.3 | -9.5 14.9 045 7 4 8.0 4.4
19500 -8.5 16.7 045 13 7 7.9 4.3 | -8.3 17.1 040 10 5 8.0 4.4
19000 -7.3 18.9 045 13 7 7.9 4.3 | -6.5 20.3 035 13 7 7.9 4.3
18500 -6.2 20.8 040 13 7 7.9 4.3 | -5.4 22.3 030 13 7 7.9 4.3
18000 -5.0 23.0 035 13 7 7.9 4.3 | -4.3 24.3 025 13 7 7.4 4.0
17500 -3.9 25.0 035 13 7 8.0 4.4 | -3.2 26.2 025 12 6 7.0 3.8
17000 -2.7 27.1 035 13 7 8.0 4.4 | -2.2 28.0 020 12 6 7.0 3.8
16500 -1.5 29.3 035 13 6 8.7 4.8 | -1.2 29.8 020 11 6 7.3 4.0
16000 -0.3 31.5 030 12 6 8.7 4.8 | -0.2 31.6 020 10 5 7.2 4.0
15500 0.9 33.6 030 10 5 8.9 4.9 | 0.9 33.6 015 10 5 8.4 4.6
15000 2.2 36.0 025 9 5 8.9 4.9 | 2.2 36.0 010 9 5 8.7 4.8
14500 3.5 38.3 015 7 4 8.6 4.7 | 3.4 38.1 005 9 5 8.4 4.6
14000 4.7 40.5 010 7 3 8.3 4.5 | 4.4 39.9 355 8 4 8.0 4.4
13500 5.9 42.6 360 6 3 8.4 4.6 | 5.4 41.7 340 8 4 8.3 4.6
13000 7.2 45.0 360 6 3 9.2 5.1 | 6.6 43.9 330 7 4 9.0 4.9
12500 8.4 47.1 360 5 3 8.8 4.8 | 7.8 46.0 325 6 3 8.8 4.9
12000 9.5 49.1 355 5 2 7.1 3.9 | 8.8 47.8 305 4 2 5.3 2.9
11750 10.0 50.0 355 4 2 8.2 4.5 | 9.2 48.6 290 4 2 6.9 3.8
11500 10.6 51.1 350 4 2 11.2 6.2 | 9.8 49.6 270 4 2 10.6 5.8
11250 11.4 52.5 350 3 1 8.6 4.7 | 10.6 51.1 255 4 2 8.8 4.8
11000 11.8 53.2 340 1 1 5.6 3.1 | 11.0 51.8 235 5 3 5.8 3.2
10750 12.2 54.0 200 1 0 5.3 2.9 | 11.4 52.5 225 7 3 5.9 3.3
10500 12.6 54.7 180 2 1 9.9 5.4 | 11.9 53.4 215 8 4 8.0 4.4
10250 13.5 56.3 175 4 2 11.5 6.3 | 12.5 54.5 210 10 5 9.4 5.2
10000 14.1 57.4 170 5 3 7.3 4.0 | 13.1 55.6 205 11 6 7.8 4.3
9750 14.6 58.3 170 7 4 7.9 4.3 | 13.7 56.7 200 12 6 8.0 4.4
9500 15.1 59.2 170 9 5 8.1 4.4 | 14.3 57.7 200 13 7 7.9 4.3
9250 15.6 60.1 170 10 5 7.1 3.9 | 14.9 58.8 195 14 7 8.3 4.6
9000 16.1 61.0 170 11 5 8.9 4.9 | 15.5 59.9 195 13 7 9.4 5.2
8750 16.9 62.4 170 11 6 11.4 6.2 | 16.2 61.2 190 13 7 9.8 5.4
8500 17.7 63.9 170 11 6 10.5 5.8 | 16.9 62.4 190 14 7 9.7 5.3
8250 18.5 65.3 170 11 6 11.3 6.2 | 17.6 63.7 190 14 7 9.7 5.3
8000 19.5 67.1 165 11 6 18.1 10.3 | 18.4 65.1 190 13 7 11.6 6.4
7750 21.2 70.2 165 11 5 27.4 15.1 | 19.4 66.9 185 12 6 15.1 8.3
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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