Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
220
UXUS97 KPUB 211204
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0604 MDT Tuesday, May 21, 2024
This forecast is for the Air Force Academy for Tuesday, May 21, 2024:
If the trigger temperature of 50.6 F/10.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1198 ft/min (6.1 m/s)
Maximum height of thermals.................. 20501 ft MSL (12851 ft AGL)
Forecast maximum temperature................... 64.0 F/18.2 C
Time of trigger temperature.................... 0830 MDT
Time of overdevelopment........................ 1100 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 16322 ft MSL (8672 ft AGL)
Thermal soaring outlook for Wednesday 05/22.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:41:05 / 20:10:49 MDT
Total possible sunshine........... 14 hr 29 min 44 sec (869 min 44 sec)
Altitude of sun at 12:55:57 MDT... 71.40 degrees
Upper air data from numerical model forecast valid on 05/21/2024 at 0600 MDT
Freezing level.................. 10901 ft MSL (3251 ft AGL)
Convective condensation level... 13894 ft MSL (6244 ft AGL)
Lifted condensation level....... 15757 ft MSL (8107 ft AGL)
Lifted index.................... -4.7
K index......................... +22.6
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 -53.4 -64.1 230 48 25 2.8 1.5 M M M M M
45000 -49.1 -56.4 235 50 25 1.9 1.0 M M M M M
40000 -46.4 -51.5 245 60 31 1.9 1.0 M M M M M
38000 -46.1 -51.0 245 60 31 -0.4 -0.2 M M M M M
36000 -46.3 -51.3 245 59 30 -0.4 -0.2 M M M M M
34000 -46.3 -51.3 250 54 28 1.4 0.8 M M M M M
32000 -45.4 -49.7 255 43 22 1.4 0.8 M M M M M
30000 -43.8 -46.8 260 35 18 7.7 4.2 24.4 75.9 5.1 M M
29000 -41.5 -42.7 265 34 18 7.7 4.2 23.5 74.3 4.4 M M
28000 -39.2 -38.6 265 34 17 7.7 4.2 22.7 72.9 3.9 M M
27000 -36.9 -34.4 265 34 17 8.2 4.5 22.1 71.8 3.4 M M
26000 -34.2 -29.6 265 33 17 9.1 5.0 21.7 71.0 3.1 M M
25000 -31.5 -24.7 265 33 17 9.1 5.0 21.4 70.6 2.9 M M
24000 -28.8 -19.8 265 32 17 9.1 5.0 21.3 70.3 2.8 M M
23000 -26.6 -15.9 265 29 15 6.9 3.8 20.4 68.7 2.1 M M
22000 -24.0 -11.2 265 25 13 7.0 3.8 19.1 66.4 1.1 M M
21000 -21.9 -7.4 265 22 12 7.6 4.1 18.3 64.9 0.3 M M
20000 -19.7 -3.5 265 24 12 7.6 4.2 17.5 63.4 -0.4 1141 5.8
19500 -18.6 -1.5 265 25 13 7.6 4.2 17.1 62.8 -0.8 1093 5.6
19000 -17.5 0.5 265 26 13 7.6 4.2 16.8 62.2 -1.1 1045 5.3
18500 -16.4 2.5 270 26 13 7.0 3.8 16.4 61.6 -1.4 997 5.1
18000 -15.4 4.3 270 25 13 6.7 3.7 15.9 60.6 -1.9 953 4.8
17500 -14.4 6.1 270 23 12 6.9 3.8 15.4 59.7 -2.4 909 4.6
17000 -13.3 8.1 275 22 11 8.7 4.8 15.1 59.2 -2.7 859 4.4
16500 -12.0 10.4 275 21 11 8.5 4.7 14.9 58.8 -2.9 807 4.1
16000 -10.7 12.7 275 21 11 9.4 5.2 14.8 58.6 -3.1 753 3.8
15500 -9.3 15.3 275 23 12 9.5 5.2 14.7 58.5 -3.2 696 3.5
15000 -7.9 17.8 275 25 13 8.5 4.6 14.7 58.5 -3.2 639 3.2
14500 -6.8 19.8 275 26 13 7.5 4.1 14.3 57.8 -3.6 592 3.0
14000 -5.7 21.7 275 27 14 7.1 3.9 14.0 57.1 -4.0 545 2.8
13500 -4.8 23.4 280 28 14 6.2 3.4 13.4 56.1 -4.6 503 2.6
13000 -3.9 25.0 285 28 15 8.3 4.6 12.8 55.1 -5.2 462 2.3
12500 -2.9 26.8 285 30 15 3.7 2.0 12.4 54.3 -5.7 417 2.1
12000 -2.3 27.9 290 31 16 4.1 2.2 11.5 52.7 -6.6 384 2.0
11750 -2.0 28.4 290 32 16 6.6 3.6 11.1 52.1 -7.0 367 1.9
11500 -1.4 29.5 290 31 16 7.8 4.3 11.0 51.8 -7.2 342 1.7
11250 -0.9 30.4 285 30 15 6.8 3.7 10.8 51.4 -7.4 319 1.6
11000 -0.4 31.3 285 29 15 6.9 3.8 10.6 51.0 -7.6 297 1.5
10750 0.1 32.2 285 28 14 8.0 4.4 10.4 50.7 -7.9 274 1.4
10500 0.8 33.4 285 26 13 9.0 5.0 10.3 50.5 -8.0 247 1.3
10250 1.4 34.5 285 24 13 9.0 4.9 10.2 50.4 -8.1 220 1.1
10000 2.1 35.8 285 23 12 9.3 5.1 10.2 50.3 -8.1 192 1.0
9750 2.7 36.9 285 22 11 6.4 3.5 10.1 50.1 -8.3 166 0.8
9500 3.1 37.6 285 21 11 3.9 2.1 9.7 49.4 -8.7 149 0.8
9250 3.4 38.1 285 19 10 5.7 3.1 9.3 48.7 -9.1 132 0.7
9000 3.8 38.8 280 18 9 6.0 3.3 9.0 48.2 -9.4 111 0.6
8750 4.0 39.2 290 14 7 -2.1 -1.1 7.7 45.9 -10.8 92 0.5
8500 3.8 38.8 300 12 6 -1.2 -0.7 6.9 44.4 -11.7 89 0.5
8250 3.7 38.7 310 11 6 -1.6 -0.9 6.0 42.9 -12.6 85 0.4
8000 3.6 38.5 320 9 4 -1.7 -0.9 5.2 41.3 -13.5 83 0.4
7750 3.4 38.1 345 7 3 -2.2 -1.2 4.3 39.8 -14.4 80 0.4
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 * * * * * *
05/21/2024 at 0900 MDT | 05/21/2024 at 1200 MDT
|
CAPE... +3.3 LI... +0.7 | CAPE... +168.3 LI... -1.6
CINH... -2.0 K Index... +12.3 | CINH... 0.0 K Index... +22.4
|
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 -52.3 -62.1 235 44 23 3.3 1.8 | -51.9 -61.4 235 40 21 2.1 1.1
45000 -47.5 -53.5 235 52 27 0.6 0.3 | -48.9 -56.0 235 51 26 0.5 0.3
40000 -46.7 -52.1 240 61 31 0.5 0.3 | -48.2 -54.8 245 64 33 0.4 0.2
38000 -47.4 -53.3 245 62 32 -2.6 -1.4 | -48.4 -55.1 245 68 35 -0.8 -0.4
36000 -49.0 -56.2 255 60 31 -2.6 -1.4 | -48.9 -56.0 245 72 37 -0.8 -0.4
34000 -49.7 -57.5 260 58 30 4.4 2.4 | -48.9 -56.0 245 75 38 4.5 2.5
32000 -47.1 -52.8 255 54 28 4.5 2.5 | -46.3 -51.3 245 71 37 3.9 2.2
30000 -43.9 -47.0 250 49 25 7.7 4.2 | -43.4 -46.1 245 67 35 7.6 4.2
29000 -41.6 -42.9 250 47 24 7.8 4.3 | -41.1 -42.0 245 64 33 7.8 4.3
28000 -39.2 -38.6 250 44 23 7.8 4.3 | -38.7 -37.7 245 60 31 7.8 4.3
27000 -36.9 -34.4 245 42 21 8.3 4.5 | -36.4 -33.5 245 56 29 7.9 4.4
26000 -34.3 -29.7 250 41 21 8.8 4.8 | -34.0 -29.2 245 53 27 8.1 4.4
25000 -31.6 -24.9 250 41 21 8.8 4.9 | -31.6 -24.9 240 49 25 8.1 4.5
24000 -29.0 -20.2 250 40 21 8.8 4.8 | -29.2 -20.6 240 45 23 8.1 4.4
23000 -26.6 -15.9 250 39 20 7.9 4.3 | -26.8 -16.2 240 46 24 7.9 4.4
22000 -24.3 -11.7 250 37 19 7.9 4.3 | -24.4 -11.9 240 48 25 7.9 4.4
21000 -21.4 -6.5 250 34 18 7.4 4.1 | -22.0 -7.6 245 49 25 6.9 3.8
20000 -19.2 -2.6 250 32 17 7.5 4.1 | -20.2 -4.4 245 47 24 6.1 3.4
19500 -18.1 -0.6 245 31 16 7.5 4.1 | -18.9 -2.0 250 45 23 6.2 3.4
19000 -17.0 1.4 245 30 15 7.5 4.1 | -18.0 -0.4 250 44 23 6.2 3.4
18500 -15.9 3.4 245 29 15 7.2 3.9 | -17.1 1.2 250 43 22 6.1 3.3
18000 -14.9 5.2 245 27 14 7.1 3.9 | -16.2 2.8 255 41 21 6.2 3.4
17500 -13.8 7.2 245 26 13 7.1 3.9 | -15.4 4.3 255 39 20 6.8 3.7
17000 -12.8 9.0 250 24 12 7.0 3.8 | -14.2 6.4 255 37 19 8.1 4.4
16500 -11.7 10.9 255 23 12 7.1 3.9 | -13.1 8.4 260 35 18 8.0 4.4
16000 -10.7 12.7 265 22 11 6.1 3.4 | -11.9 10.6 255 32 17 8.8 4.8
15500 -9.8 14.4 275 22 11 6.2 3.4 | -10.6 12.9 255 29 15 8.8 4.8
15000 -8.8 16.2 285 22 11 6.5 3.6 | -9.3 15.3 255 25 13 8.1 4.5
14500 -7.8 18.0 290 21 11 6.8 3.7 | -8.2 17.2 255 21 11 8.0 4.4
14000 -6.7 19.9 295 21 11 7.1 3.9 | -7.0 19.4 250 18 9 8.6 4.7
13500 -5.6 21.9 300 21 11 7.7 4.2 | -5.7 21.7 250 15 8 9.3 5.1
13000 -4.5 23.9 305 21 11 9.6 5.2 | -4.3 24.3 250 13 6 11.0 6.0
12500 -3.4 25.9 305 24 12 4.3 2.3 | -2.8 27.0 245 10 5 8.1 4.5
12000 -2.7 27.1 310 29 15 4.9 2.7 | -1.5 29.3 245 7 4 8.8 4.8
11750 -2.3 27.9 310 30 15 5.5 3.0 | -0.8 30.6 240 6 3 9.4 5.2
11500 -1.9 28.6 310 27 14 6.6 3.6 | -0.1 31.8 240 6 3 9.6 5.3
11250 -1.4 29.5 310 25 13 7.4 4.0 | 0.6 33.1 235 5 3 9.6 5.3
11000 -0.9 30.4 310 22 11 7.4 4.1 | 1.3 34.3 235 4 2 9.4 5.2
10750 -0.4 31.3 310 20 10 8.1 4.4 | 2.0 35.6 235 4 2 8.7 4.8
10500 0.2 32.4 310 19 10 8.4 4.6 | 2.6 36.7 230 4 2 8.9 4.9
10250 0.8 33.4 315 17 9 10.2 5.6 | 3.3 37.9 230 3 2 10.9 6.0
10000 1.6 34.9 315 16 8 10.6 5.8 | 4.2 39.6 225 3 2 11.2 6.1
9750 2.3 36.1 315 16 8 8.6 4.7 | 5.0 41.0 225 3 1 9.8 5.4
9500 2.9 37.2 315 15 8 7.4 4.1 | 5.7 42.3 220 3 1 9.3 5.1
9250 3.4 38.1 310 14 7 9.9 5.4 | 6.4 43.5 215 3 1 10.6 5.8
9000 4.3 39.7 310 13 6 11.7 6.4 | 7.2 45.0 210 2 1 11.3 6.2
8750 5.1 41.2 310 11 6 9.7 5.3 | 8.0 46.4 205 2 1 10.0 5.5
8500 5.7 42.3 310 10 5 9.6 5.3 | 8.8 47.8 200 2 1 10.5 5.8
8250 6.4 43.5 310 9 4 8.3 4.5 | 9.5 49.1 195 2 1 8.3 4.5
8000 7.1 44.8 310 8 4 12.8 7.0 | 10.2 50.4 180 2 1 14.3 7.8
7750 8.5 47.3 315 7 3 24.5 13.5 | 11.9 53.4 170 1 1 30.8 16.9
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
05/21/2024 at 1500 MDT | 05/21/2024 at 1800 MDT
|
CAPE... +320.8 LI... -0.9 | CAPE... +355.7 LI... -3.0
CINH... -12.2 K Index... +25.7 | CINH... -13.6 K Index... +22.1
|
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 -52.1 -61.8 240 38 20 2.2 1.2 | -51.7 -61.1 240 42 22 1.2 0.7
45000 -49.0 -56.2 240 56 29 -0.2 -0.1 | -50.2 -58.4 250 56 29 -1.3 -0.7
40000 -49.3 -56.7 250 72 37 -0.2 -0.1 | -52.2 -62.0 255 81 41 -1.4 -0.8
38000 -49.5 -57.1 250 79 41 -0.6 -0.3 | -51.7 -61.1 255 85 44 2.3 1.3
36000 -49.9 -57.8 250 87 45 -0.6 -0.3 | -50.3 -58.5 255 87 45 2.3 1.3
34000 -49.9 -57.8 250 93 48 3.8 2.1 | -48.7 -55.7 255 88 45 4.6 2.5
32000 -47.6 -53.7 245 82 42 3.4 1.9 | -45.6 -50.1 255 82 42 4.5 2.5
30000 -44.8 -48.6 240 71 37 8.3 4.5 | -42.4 -44.3 255 77 40 7.3 4.0
29000 -42.2 -44.0 240 63 32 8.4 4.6 | -40.2 -40.4 255 74 38 7.4 4.1
28000 -39.7 -39.5 235 55 28 8.4 4.6 | -38.0 -36.4 255 70 36 7.4 4.1
27000 -37.2 -35.0 235 47 24 8.4 4.6 | -35.8 -32.4 255 67 34 7.5 4.1
26000 -34.7 -30.5 235 46 23 8.3 4.6 | -33.5 -28.3 250 62 32 7.6 4.2
25000 -32.2 -26.0 240 44 23 8.3 4.6 | -31.2 -24.2 245 57 29 7.6 4.2
24000 -29.8 -21.6 245 43 22 8.4 4.6 | -29.0 -20.2 245 53 27 7.7 4.2
23000 -27.3 -17.1 250 41 21 8.4 4.6 | -26.6 -15.9 240 50 26 8.0 4.4
22000 -24.8 -12.6 250 40 20 8.5 4.6 | -24.3 -11.7 235 47 24 8.1 4.4
21000 -22.3 -8.1 255 38 20 8.4 4.6 | -22.0 -7.6 230 45 23 6.5 3.6
20000 -19.8 -3.6 255 37 19 8.4 4.6 | -20.3 -4.5 235 44 23 5.8 3.2
19500 -18.6 -1.5 255 36 19 8.4 4.6 | -19.4 -2.9 240 44 23 5.9 3.2
19000 -16.7 1.9 255 36 18 8.4 4.6 | -18.5 -1.3 240 45 23 5.9 3.2
18500 -15.5 4.1 255 34 18 7.9 4.3 | -17.2 1.0 245 45 23 7.0 3.9
18000 -14.4 6.1 255 31 16 7.9 4.3 | -16.2 2.8 250 45 23 7.0 3.8
17500 -13.2 8.2 255 29 15 7.7 4.2 | -15.1 4.8 250 45 23 7.8 4.3
17000 -12.1 10.2 255 28 14 7.3 4.0 | -13.9 7.0 255 43 22 8.5 4.7
16500 -11.1 12.0 255 27 14 7.3 4.0 | -12.7 9.1 255 42 22 8.6 4.7
16000 -10.1 13.8 255 26 13 6.8 3.7 | -11.4 11.5 255 40 20 8.8 4.8
15500 -9.1 15.6 255 25 13 6.9 3.8 | -10.1 13.8 255 37 19 8.8 4.8
15000 -8.1 17.4 255 23 12 7.1 3.9 | -8.8 16.2 255 34 17 9.7 5.3
14500 -7.0 19.4 255 22 11 7.1 3.9 | -7.3 18.9 255 31 16 9.8 5.4
14000 -6.0 21.2 255 21 11 7.6 4.1 | -5.9 21.4 255 29 15 9.7 5.3
13500 -4.8 23.4 250 20 10 8.0 4.4 | -4.4 24.1 255 28 14 9.7 5.3
13000 -3.7 25.3 250 18 9 10.6 5.8 | -3.0 26.6 255 27 14 10.4 5.7
12500 -2.1 28.2 245 17 9 8.0 4.4 | -1.6 29.1 255 25 13 8.3 4.5
12000 -0.8 30.6 235 14 7 8.5 4.7 | -0.4 31.3 255 23 12 8.2 4.5
11750 -0.2 31.6 230 14 7 8.4 4.6 | 0.2 32.4 255 22 11 7.6 4.2
11500 0.4 32.7 225 13 7 8.8 4.8 | 0.8 33.4 255 20 11 8.1 4.5
11250 1.1 34.0 220 12 6 9.5 5.2 | 1.4 34.5 255 19 10 9.0 4.9
11000 1.8 35.2 215 12 6 8.5 4.7 | 2.0 35.6 255 17 9 7.7 4.2
10750 2.4 36.3 210 11 6 6.8 3.8 | 2.5 36.5 255 15 8 6.0 3.3
10500 2.8 37.0 205 11 6 6.7 3.7 | 2.9 37.2 255 13 7 6.3 3.5
10250 3.4 38.1 200 10 5 8.7 4.8 | 3.5 38.3 255 11 6 10.0 5.5
10000 4.1 39.4 190 10 5 9.0 4.9 | 4.3 39.7 260 9 5 9.7 5.3
9750 4.7 40.5 185 9 5 7.9 4.3 | 4.8 40.6 260 7 4 7.0 3.9
9500 5.2 41.4 180 9 4 7.1 3.9 | 5.3 41.5 260 5 3 6.4 3.5
9250 5.8 42.4 170 8 4 9.9 5.4 | 5.8 42.4 265 3 2 9.9 5.4
9000 6.6 43.9 155 8 4 11.4 6.3 | 6.7 44.1 305 1 1 11.4 6.3
8750 7.4 45.3 155 8 4 9.5 5.2 | 7.4 45.3 355 1 0 8.8 4.8
8500 8.1 46.6 150 8 4 9.7 5.3 | 8.1 46.6 030 1 1 9.7 5.3
8250 8.8 47.8 150 8 4 9.4 5.1 | 8.8 47.8 045 2 1 8.6 4.7
8000 9.5 49.1 145 8 4 11.8 6.4 | 9.5 49.1 045 2 1 10.7 5.8
7750 10.6 51.1 140 7 3 16.4 9.0 | 10.5 50.9 045 3 1 16.5 9.0
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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