Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
317
UXUS97 KPUB 031217
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0617 MDT Friday, May 3, 2024
This forecast is for the Air Force Academy for Friday, May 3, 2024:
If the trigger temperature of 53.9 F/12.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1214 ft/min (6.2 m/s)
Maximum height of thermals.................. 22339 ft MSL (14717 ft AGL)
Forecast maximum temperature................... 68.0 F/20.5 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ 1500 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................. 18895 ft MSL (11273 ft AGL)
Thermal soaring outlook for Saturday 05/04..... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:57:52 / 19:54:19 MDT
Total possible sunshine........... 13 hr 56 min 26 sec (836 min 26 sec)
Altitude of sun at 12:56:05 MDT... 66.99 degrees
Upper air data from numerical model forecast valid on 05/03/2024 at 0600 MDT
Freezing level.................. 7668 ft MSL (46 ft AGL)
Additional freezing level....... 11669 ft MSL (4047 ft AGL)
Convective condensation level... 17248 ft MSL (9626 ft AGL)
Lifted condensation level....... 19333 ft MSL (11711 ft AGL)
Lifted index.................... -1.9
K index......................... +2.0
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 -54.6 -66.3 250 35 18 0.1 0.1 M M M M M
45000 -54.5 -66.1 245 45 23 -2.2 -1.2 M M M M M
40000 -59.3 -74.7 255 64 33 -3.2 -1.7 M M M M M
38000 -58.7 -73.7 260 68 35 5.1 2.8 M M M M M
36000 -55.6 -68.1 260 68 35 5.1 2.8 M M M M M
34000 -51.8 -61.2 260 68 35 6.9 3.8 M M M M M
32000 -47.6 -53.7 260 64 33 7.0 3.8 M M M M M
30000 -43.2 -45.8 260 59 31 8.2 4.5 25.0 77.0 3.9 M M
29000 -40.8 -41.4 260 56 29 8.3 4.5 24.4 75.8 3.4 M M
28000 -38.3 -36.9 265 52 27 8.3 4.5 23.8 74.9 3.0 M M
27000 -35.8 -32.4 265 49 25 8.4 4.6 23.4 74.1 2.7 M M
26000 -33.3 -27.9 260 49 25 8.5 4.7 22.8 73.1 2.3 M M
25000 -30.7 -23.3 260 50 26 8.5 4.7 22.4 72.3 1.9 M M
24000 -28.2 -18.8 255 51 26 8.1 4.4 22.0 71.6 1.7 M M
23000 -26.2 -15.2 255 50 26 6.6 3.6 20.9 69.6 0.7 M M
22000 -24.2 -11.6 260 48 25 6.6 3.6 19.8 67.6 -0.2 1393 7.1
21000 -21.7 -7.1 260 45 23 7.2 3.9 18.5 65.3 -1.3 1281 6.5
20000 -19.6 -3.3 255 41 21 7.1 3.9 17.6 63.6 -2.2 1188 6.0
19500 -18.5 -1.3 255 39 20 7.1 3.9 17.1 62.8 -2.6 1142 5.8
19000 -17.5 0.5 255 37 19 7.1 3.9 16.7 62.1 -3.0 1095 5.6
18500 -16.4 2.5 255 36 19 7.1 3.9 16.3 61.3 -3.4 1049 5.3
18000 -15.3 4.5 255 36 19 7.1 3.9 15.8 60.5 -3.8 1003 5.1
17500 -14.3 6.3 260 36 19 6.8 3.7 15.4 59.7 -4.2 956 4.9
17000 -13.4 7.9 260 36 19 6.2 3.4 14.8 58.7 -4.8 914 4.6
16500 -12.5 9.5 260 37 19 6.1 3.3 14.2 57.6 -5.4 872 4.4
16000 -11.5 11.3 260 36 19 7.3 4.0 13.7 56.7 -5.9 828 4.2
15500 -10.4 13.3 260 35 18 7.2 3.9 13.3 56.0 -6.3 782 4.0
15000 -9.3 15.3 260 33 17 8.2 4.5 12.9 55.3 -6.7 734 3.7
14500 -8.1 17.4 260 33 17 8.4 4.6 12.7 54.9 -7.0 682 3.5
14000 -6.9 19.6 260 32 16 9.1 5.0 12.5 54.5 -7.3 630 3.2
13500 -5.4 22.3 255 32 16 9.8 5.4 12.5 54.5 -7.3 573 2.9
13000 -4.0 24.8 255 32 16 12.1 6.6 12.5 54.5 -7.4 515 2.6
12500 -2.3 27.9 255 32 16 8.0 4.4 12.7 54.9 -7.2 450 2.3
12000 -1.1 30.0 250 31 16 8.7 4.8 12.5 54.5 -7.5 398 2.0
11750 -0.4 31.3 250 31 16 9.9 5.4 12.5 54.4 -7.5 370 1.9
11500 0.4 32.7 250 30 15 9.9 5.4 12.5 54.5 -7.5 340 1.7
11250 1.1 34.0 245 29 15 10.0 5.5 12.5 54.5 -7.5 311 1.6
11000 1.8 35.2 245 29 15 8.9 4.9 12.5 54.5 -7.5 281 1.4
10750 2.4 36.3 240 28 14 6.8 3.7 12.3 54.2 -7.7 257 1.3
10500 2.9 37.2 240 27 14 5.8 3.2 12.0 53.7 -8.0 236 1.2
10250 3.3 37.9 240 27 14 9.1 5.0 11.8 53.3 -8.3 214 1.1
10000 4.0 39.2 240 27 14 6.7 3.7 11.8 53.2 -8.3 185 0.9
9750 4.2 39.6 235 26 13 -0.8 -0.4 11.2 52.2 -9.0 174 0.9
9500 4.0 39.2 235 24 13 -2.5 -1.4 10.3 50.6 -9.9 172 0.9
9250 3.8 38.8 230 23 12 -0.2 -0.1 9.4 49.0 -10.8 170 0.9
9000 3.7 38.7 225 21 11 -2.6 -1.4 8.7 47.7 -11.7 165 0.8
8750 3.3 37.9 215 20 10 -7.3 -4.0 7.5 45.5 -12.9 172 0.9
8500 2.7 36.9 210 20 10 -7.5 -4.1 6.2 43.2 -14.3 182 0.9
8250 2.1 35.8 200 19 10 -6.3 -3.5 4.9 40.9 -15.6 192 1.0
8000 1.6 34.9 195 19 10 -8.1 -4.4 3.7 38.7 -16.9 200 1.0
7750 0.7 33.3 190 14 7 -14.6 -8.0 2.1 35.9 -18.5 219 1.1
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 * * * * * *
05/03/2024 at 0900 MDT | 05/03/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.6 | CAPE... +40.1 LI... +0.4
CINH... 0.0 K Index... +0.8 | CINH... -4.7 K Index... +12.8
|
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 -65.6 245 38 20 -0.2 -0.1 | -54.2 -65.6 245 40 21 -0.1 -0.0
45000 -54.6 -66.3 250 46 24 -2.3 -1.3 | -54.4 -65.9 250 52 27 -2.3 -1.3
40000 -59.6 -75.3 255 65 34 -3.4 -1.8 | -59.7 -75.5 255 65 33 -3.6 -2.0
38000 -58.9 -74.0 255 67 34 5.5 3.0 | -58.9 -74.0 255 65 33 5.8 3.2
36000 -55.6 -68.1 260 62 32 5.5 3.0 | -55.0 -67.0 255 59 31 5.8 3.2
34000 -51.5 -60.7 260 57 29 7.3 4.0 | -51.3 -60.3 255 55 28 7.2 3.9
32000 -47.2 -53.0 255 54 28 7.3 4.0 | -47.0 -52.6 255 52 27 7.2 4.0
30000 -42.6 -44.7 255 51 26 8.2 4.5 | -42.4 -44.3 250 49 25 8.4 4.6
29000 -40.1 -40.2 255 51 26 8.3 4.5 | -39.9 -39.8 250 49 25 8.4 4.6
28000 -37.6 -35.7 250 51 26 8.3 4.5 | -37.4 -35.3 250 50 25 8.4 4.6
27000 -35.2 -31.4 250 50 26 7.9 4.3 | -34.9 -30.8 255 50 25 8.1 4.5
26000 -32.9 -27.2 250 50 26 7.7 4.2 | -32.5 -26.5 255 49 25 8.0 4.4
25000 -30.6 -23.1 250 50 26 7.7 4.2 | -30.1 -22.2 255 49 25 8.0 4.4
24000 -28.3 -18.9 250 49 25 7.5 4.1 | -27.7 -17.9 255 49 25 7.8 4.3
23000 -26.2 -15.2 250 47 24 7.0 3.9 | -25.5 -13.9 255 48 24 7.5 4.1
22000 -24.1 -11.4 250 45 23 7.0 3.9 | -23.2 -9.8 250 46 24 7.5 4.1
21000 -21.5 -6.7 250 41 21 7.4 4.1 | -20.6 -5.1 250 43 22 6.1 3.3
20000 -19.3 -2.7 245 33 17 7.4 4.1 | -18.7 -1.7 245 37 19 6.2 3.4
19500 -18.2 -0.8 240 30 15 7.4 4.1 | -17.8 -0.0 240 34 18 6.3 3.4
19000 -17.1 1.2 230 26 14 7.4 4.1 | -16.9 1.6 235 31 16 6.4 3.5
18500 -16.0 3.2 230 25 13 6.9 3.8 | -16.0 3.2 235 31 16 5.0 2.8
18000 -15.0 5.0 240 27 14 6.9 3.8 | -15.3 4.5 245 35 18 5.2 2.8
17500 -14.0 6.8 250 29 15 6.7 3.7 | -14.6 5.7 255 39 20 6.3 3.4
17000 -13.0 8.6 255 32 16 6.5 3.6 | -13.5 7.7 255 37 19 7.7 4.2
16500 -12.0 10.4 260 34 18 6.5 3.6 | -12.4 9.7 255 35 18 7.8 4.3
16000 -11.1 12.0 260 37 19 6.6 3.6 | -11.1 12.0 255 33 17 9.8 5.4
15500 -10.1 13.8 260 40 20 6.6 3.6 | -9.7 14.5 255 31 16 9.6 5.3
15000 -9.1 15.6 260 41 21 7.9 4.3 | -8.3 17.1 250 29 15 9.5 5.2
14500 -7.9 17.8 260 40 21 8.1 4.4 | -6.9 19.6 250 29 15 9.4 5.2
14000 -6.7 19.9 260 39 20 8.9 4.9 | -5.5 22.1 250 28 14 9.2 5.1
13500 -5.3 22.5 260 37 19 9.6 5.3 | -4.1 24.6 250 27 14 9.3 5.1
13000 -3.9 25.0 255 35 18 12.9 7.1 | -2.8 27.0 245 26 13 12.3 6.7
12500 -2.3 27.9 255 34 18 6.7 3.7 | -1.1 30.0 245 25 13 7.1 3.9
12000 -1.1 30.0 255 33 17 8.4 4.6 | 0.1 32.2 240 24 12 8.6 4.7
11750 -0.4 31.3 250 32 17 10.0 5.5 | 0.8 33.4 240 24 12 10.0 5.5
11500 0.4 32.7 250 31 16 9.8 5.4 | 1.5 34.7 240 23 12 9.3 5.1
11250 1.1 34.0 250 30 15 9.7 5.3 | 2.1 35.8 240 23 12 8.7 4.8
11000 1.8 35.2 250 29 15 9.2 5.0 | 2.8 37.0 235 22 11 8.6 4.7
10750 2.4 36.3 245 28 15 8.2 4.5 | 3.4 38.1 235 21 11 7.8 4.3
10500 3.0 37.4 245 28 14 8.0 4.4 | 4.0 39.2 230 21 11 8.2 4.5
10250 3.7 38.7 240 27 14 10.9 6.0 | 4.7 40.5 230 20 10 11.3 6.2
10000 4.6 40.3 240 27 14 9.6 5.2 | 5.6 42.1 225 19 10 11.0 6.0
9750 5.1 41.2 240 27 14 5.6 3.1 | 6.3 43.3 225 19 10 8.4 4.6
9500 5.4 41.7 240 26 13 3.8 2.1 | 6.9 44.4 220 18 9 7.6 4.2
9250 5.8 42.4 240 25 13 9.6 5.2 | 7.5 45.5 215 17 9 10.3 5.7
9000 6.6 43.9 240 25 13 6.5 3.6 | 8.4 47.1 210 17 9 11.9 6.5
8750 6.5 43.7 235 22 11 -3.0 -1.6 | 9.2 48.6 205 16 8 9.9 5.4
8500 6.3 43.3 225 19 10 -1.0 -0.5 | 9.9 49.8 205 16 8 10.5 5.7
8250 6.1 43.0 215 17 9 -4.3 -2.3 | 10.7 51.3 200 16 8 9.1 5.0
8000 5.9 42.6 210 15 8 4.6 2.5 | 11.5 52.7 200 15 8 16.2 8.9
7750 7.1 44.8 200 13 7 27.8 15.3 | 13.2 55.8 200 14 7 31.6 17.3
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
05/03/2024 at 1500 MDT | 05/03/2024 at 1800 MDT
|
CAPE... +154.5 LI... -1.2 | CAPE... +102.2 LI... -0.6
CINH... -3.5 K Index... +22.8 | CINH... -5.2 K Index... +20.7
|
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 -55.4 -67.7 250 40 21 0.2 0.1 | -55.4 -67.7 250 40 21 -0.0 -0.0
45000 -55.2 -67.4 250 56 29 -2.3 -1.2 | -55.5 -67.9 255 52 27 -2.1 -1.2
40000 -59.7 -75.5 255 65 33 -3.1 -1.7 | -59.7 -75.5 255 60 31 -2.8 -1.5
38000 -58.6 -73.5 255 66 34 6.0 3.3 | -58.6 -73.5 255 61 32 5.8 3.2
36000 -54.5 -66.1 255 65 34 6.0 3.3 | -54.7 -66.5 255 61 32 5.8 3.2
34000 -50.8 -59.4 255 63 32 6.8 3.7 | -50.9 -59.6 260 60 31 7.4 4.0
32000 -46.7 -52.1 250 56 29 6.8 3.7 | -46.5 -51.7 255 56 29 7.4 4.0
30000 -42.3 -44.1 250 52 27 8.1 4.4 | -42.1 -43.8 255 53 27 7.4 4.0
29000 -39.9 -39.8 250 51 26 8.1 4.4 | -39.9 -39.8 255 52 27 7.4 4.0
28000 -37.5 -35.5 250 51 26 8.1 4.4 | -37.7 -35.9 255 50 26 7.4 4.0
27000 -35.1 -31.2 255 50 26 7.7 4.2 | -35.5 -31.9 255 49 25 7.6 4.2
26000 -32.8 -27.0 255 50 26 7.6 4.2 | -33.2 -27.8 255 48 25 7.6 4.2
25000 -30.5 -22.9 255 49 25 7.6 4.2 | -30.9 -23.6 255 46 24 7.6 4.2
24000 -28.2 -18.8 260 49 25 7.1 3.9 | -28.6 -19.5 255 45 23 7.3 4.0
23000 -26.4 -15.5 255 46 24 6.3 3.4 | -26.6 -15.9 250 40 21 6.8 3.7
22000 -24.5 -12.1 255 43 22 6.3 3.5 | -24.0 -11.2 245 35 18 7.0 3.8
21000 -22.6 -8.7 250 40 21 8.2 4.5 | -21.8 -7.2 240 32 16 8.9 4.9
20000 -19.4 -2.9 250 36 19 8.8 4.8 | -19.2 -2.6 240 29 15 8.9 4.9
19500 -18.1 -0.6 250 35 18 8.8 4.8 | -17.9 -0.2 245 28 14 8.9 4.9
19000 -16.8 1.8 245 33 17 8.9 4.9 | -16.6 2.1 245 26 14 9.0 4.9
18500 -15.5 4.1 245 32 16 8.8 4.8 | -15.3 4.5 245 25 13 8.3 4.6
18000 -14.2 6.4 245 31 16 8.8 4.8 | -14.1 6.6 250 24 13 8.4 4.6
17500 -13.0 8.6 245 30 15 8.9 4.9 | -12.8 9.0 255 24 12 9.0 5.0
17000 -11.6 11.1 245 29 15 8.9 4.9 | -11.4 11.5 255 23 12 9.4 5.2
16500 -10.3 13.5 245 28 15 9.0 4.9 | -10.0 14.0 255 22 11 9.5 5.2
16000 -8.9 16.0 245 28 14 9.6 5.3 | -8.6 16.5 255 21 11 9.8 5.4
15500 -7.5 18.5 245 28 14 9.6 5.3 | -7.1 19.2 255 21 11 9.8 5.4
15000 -6.0 21.2 245 27 14 9.5 5.2 | -5.7 21.7 255 21 11 9.6 5.3
14500 -4.6 23.7 245 27 14 9.5 5.2 | -4.2 24.4 255 21 11 9.6 5.3
14000 -3.2 26.2 245 26 13 9.5 5.2 | -2.8 27.0 255 20 10 10.0 5.5
13500 -1.8 28.8 240 25 13 9.6 5.3 | -1.3 29.7 260 20 10 10.2 5.6
13000 -0.4 31.3 240 24 12 11.6 6.3 | 0.3 32.5 260 20 10 12.3 6.8
12500 1.2 34.2 235 23 12 8.0 4.4 | 1.9 35.4 260 19 10 8.0 4.4
12000 2.5 36.5 235 22 11 8.8 4.8 | 3.2 37.8 260 19 10 8.8 4.8
11750 3.2 37.8 230 21 11 9.3 5.1 | 3.9 39.0 260 19 10 9.1 5.0
11500 3.9 39.0 230 21 11 9.4 5.1 | 4.6 40.3 260 18 9 9.5 5.2
11250 4.6 40.3 225 20 11 9.6 5.3 | 5.3 41.5 260 18 9 9.9 5.4
11000 5.3 41.5 225 20 10 8.9 4.9 | 6.0 42.8 260 18 9 9.4 5.2
10750 5.9 42.6 220 19 10 7.5 4.1 | 6.7 44.1 260 17 9 8.6 4.7
10500 6.4 43.5 215 19 10 8.3 4.5 | 7.4 45.3 260 17 9 9.1 5.0
10250 7.2 45.0 210 18 9 11.5 6.3 | 8.1 46.6 260 16 8 10.8 5.9
10000 8.1 46.6 210 18 9 11.2 6.2 | 8.9 48.0 260 16 8 10.6 5.8
9750 8.8 47.8 210 18 9 9.0 5.0 | 9.7 49.5 260 15 8 9.4 5.2
9500 9.5 49.1 205 18 9 8.3 4.6 | 10.3 50.5 255 15 8 8.9 4.9
9250 10.1 50.2 205 18 9 10.4 5.7 | 11.0 51.8 255 14 7 10.9 6.0
9000 11.0 51.8 200 17 9 11.5 6.3 | 11.9 53.4 255 14 7 11.3 6.2
8750 11.8 53.2 200 17 9 9.8 5.4 | 12.7 54.9 255 13 7 9.1 5.0
8500 12.5 54.5 200 17 9 10.2 5.6 | 13.3 55.9 255 13 6 9.2 5.0
8250 13.2 55.8 200 17 9 9.0 4.9 | 14.0 57.2 255 12 6 9.5 5.2
8000 14.0 57.2 195 16 8 13.0 7.1 | 14.8 58.6 255 11 6 10.3 5.7
7750 15.3 59.5 195 15 8 22.8 12.5 | 15.5 59.9 250 9 5 10.5 5.7
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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