Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
750
UXUS97 KPUB 041247
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0647 MDT Saturday, May 4, 2024
This forecast is for the Air Force Academy for Saturday, May 4, 2024:
If the trigger temperature of 53.5 F/11.9 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 635 ft/min (3.2 m/s)
Maximum height of thermals.................. 16431 ft MSL (8814 ft AGL)
Forecast maximum temperature................... 59.0 F/15.5 C
Time of trigger temperature.................... 1245 MDT
Time of overdevelopment........................ 1900 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................. 11601 ft MSL (3984 ft AGL)
Thermal soaring outlook for Sunday 05/05....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:56:44 / 19:55:16 MDT
Total possible sunshine........... 13 hr 58 min 32 sec (838 min 32 sec)
Altitude of sun at 12:56:00 MDT... 67.28 degrees
Upper air data from numerical model forecast valid on 05/04/2024 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 15151 ft MSL (7534 ft AGL)
Lifted condensation level....... 15469 ft MSL (7852 ft AGL)
Lifted index.................... -0.6
K index......................... +12.5
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 -56.2 -69.2 250 41 21 1.1 0.6 M M M M M
45000 -54.8 -66.6 250 46 24 -2.1 -1.1 M M M M M
40000 -58.3 -72.9 255 49 25 -2.4 -1.3 M M M M M
38000 -57.0 -70.6 255 48 25 4.7 2.6 M M M M M
36000 -54.2 -65.6 255 46 24 4.7 2.6 M M M M M
34000 -51.0 -59.8 250 43 22 7.2 4.0 M M M M M
32000 -46.6 -51.9 250 40 21 7.2 4.0 M M M M M
30000 -42.3 -44.1 250 37 19 7.1 3.9 26.4 79.5 8.8 M M
29000 -40.1 -40.2 250 36 18 7.1 3.9 25.3 77.6 8.0 M M
28000 -38.0 -36.4 250 34 18 7.1 3.9 24.4 75.9 7.4 M M
27000 -35.8 -32.4 250 33 17 7.9 4.4 23.6 74.4 6.8 M M
26000 -33.4 -28.1 250 32 17 8.1 4.4 22.8 73.1 6.3 M M
25000 -31.0 -23.8 250 31 16 8.1 4.4 22.2 72.0 5.9 M M
24000 -28.6 -19.5 250 30 16 8.4 4.6 21.7 71.1 5.6 M M
23000 -25.9 -14.6 255 30 15 8.8 4.8 21.3 70.3 5.3 M M
22000 -22.6 -8.7 260 29 15 8.8 4.8 20.9 69.6 5.0 M M
21000 -20.2 -4.4 260 29 15 6.9 3.8 20.3 68.6 4.6 M M
20000 -18.1 -0.6 265 31 16 7.0 3.8 19.3 66.8 3.7 M M
19500 -17.1 1.2 265 32 16 7.0 3.9 18.9 66.0 3.4 M M
19000 -16.0 3.2 265 32 17 7.2 4.0 18.5 65.3 3.0 M M
18500 -15.2 4.6 265 33 17 4.6 2.5 17.8 64.1 2.4 M M
18000 -14.5 5.9 265 34 18 4.9 2.7 17.0 62.6 1.7 M M
17500 -13.8 7.2 265 35 18 6.1 3.4 16.2 61.2 0.9 M M
17000 -12.7 9.1 260 35 18 6.9 3.8 15.7 60.3 0.5 M M
16500 -11.7 10.9 260 35 18 7.3 4.0 15.3 59.5 0.0 M M
16000 -10.5 13.1 255 35 18 9.1 5.0 15.1 59.1 -0.2 787 4.0
15500 -9.2 15.4 255 35 18 8.9 4.9 14.9 58.9 -0.3 733 3.7
15000 -7.8 18.0 255 34 17 9.7 5.3 14.9 58.8 -0.4 677 3.4
14500 -6.4 20.5 255 33 17 9.7 5.3 14.9 58.8 -0.5 619 3.1
14000 -4.9 23.2 255 32 16 9.1 5.0 14.8 58.7 -0.5 561 2.9
13500 -3.6 25.5 255 30 15 9.0 4.9 14.7 58.5 -0.6 507 2.6
13000 -2.3 27.9 255 28 15 8.7 4.8 14.6 58.3 -0.8 453 2.3
12500 -1.1 30.0 255 26 14 7.0 3.8 14.3 57.8 -1.1 403 2.0
12000 -0.1 31.8 250 25 13 3.3 1.8 13.9 57.0 -1.5 358 1.8
11750 -0.2 31.6 250 24 12 -1.5 -0.8 13.1 55.5 -2.3 352 1.8
11500 -0.3 31.5 245 22 11 -0.7 -0.4 12.3 54.1 -3.2 347 1.8
11250 -0.4 31.3 240 20 10 -0.9 -0.5 11.4 52.6 -4.0 343 1.7
11000 -0.5 31.1 235 19 10 -3.4 -1.8 10.5 51.0 -4.9 340 1.7
10750 -0.9 30.4 235 16 8 -5.9 -3.2 9.4 48.9 -6.0 345 1.8
10500 -1.3 29.7 230 14 7 -5.4 -2.9 8.2 46.7 -7.2 350 1.8
10250 -1.8 28.8 225 12 6 -5.7 -3.1 7.0 44.6 -8.4 355 1.8
10000 -2.1 28.2 210 11 5 -2.3 -1.2 5.9 42.6 -9.5 359 1.8
9750 -2.1 28.2 210 8 4 0.4 0.2 5.1 41.2 -10.3 352 1.8
9500 -2.2 28.0 205 6 3 -0.4 -0.2 4.4 39.9 -11.1 345 1.8
9250 -2.2 28.0 190 4 2 0.2 0.1 3.6 38.5 -11.8 338 1.7
9000 -2.0 28.4 165 4 2 4.5 2.5 3.0 37.4 -12.5 327 1.7
8750 -1.6 29.1 155 3 2 6.9 3.8 2.8 37.0 -12.7 305 1.5
8500 -1.1 30.0 145 3 2 7.4 4.1 2.5 36.5 -13.0 283 1.4
8250 -0.6 30.9 130 3 1 2.8 1.5 2.3 36.1 -13.3 261 1.3
8000 -0.7 30.7 170 2 1 -4.2 -2.3 1.4 34.6 -14.2 258 1.3
7750 -1.0 30.2 150 1 1 -1.3 -0.7 0.4 32.8 -15.2 258 1.3
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 * * * * * *
05/04/2024 at 0900 MDT | 05/04/2024 at 1200 MDT
|
CAPE... +1.6 LI... +2.3 | CAPE... 0.0 LI... +2.1
CINH... 0.0 K Index... +4.6 | CINH... 0.0 K Index... +6.1
|
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 -55.9 -68.6 250 39 20 1.1 0.6 | -55.9 -68.6 245 40 21 1.2 0.7
45000 -54.5 -66.1 250 42 21 -2.5 -1.4 | -54.2 -65.6 245 44 22 -2.9 -1.6
40000 -58.8 -73.8 245 44 22 -2.9 -1.6 | -59.3 -74.7 240 38 20 -3.1 -1.7
38000 -57.5 -71.5 245 43 22 5.1 2.8 | -57.7 -71.9 240 37 19 5.4 3.0
36000 -54.4 -65.9 245 41 21 5.1 2.8 | -54.4 -65.9 240 37 19 5.4 3.0
34000 -51.0 -59.8 245 39 20 7.1 3.9 | -50.9 -59.6 240 36 18 6.9 3.8
32000 -46.7 -52.1 245 35 18 7.1 3.9 | -46.7 -52.1 240 33 17 6.9 3.8
30000 -42.3 -44.1 245 32 17 7.7 4.2 | -42.5 -44.5 240 31 16 7.5 4.1
29000 -40.0 -40.0 245 32 16 7.7 4.2 | -40.2 -40.4 240 29 15 7.5 4.1
28000 -37.7 -35.9 245 31 16 7.7 4.2 | -37.9 -36.2 240 28 14 7.5 4.1
27000 -35.4 -31.7 245 30 15 7.5 4.1 | -35.7 -32.3 240 26 14 8.1 4.4
26000 -33.2 -27.8 245 28 15 7.5 4.1 | -33.2 -27.8 240 25 13 8.1 4.5
25000 -30.9 -23.6 245 27 14 7.5 4.1 | -30.8 -23.4 245 25 13 8.1 4.5
24000 -28.7 -19.7 245 25 13 8.2 4.5 | -28.4 -19.1 245 24 12 8.2 4.5
23000 -26.1 -15.0 245 24 12 8.7 4.8 | -25.3 -13.5 245 21 11 8.2 4.5
22000 -22.8 -9.0 250 22 11 8.7 4.8 | -22.9 -9.2 245 19 10 8.2 4.5
21000 -20.2 -4.4 255 21 11 8.1 4.5 | -20.4 -4.7 245 18 9 8.0 4.4
20000 -17.8 -0.0 260 22 11 8.1 4.5 | -18.0 -0.4 245 17 9 8.0 4.4
19500 -16.6 2.1 265 23 12 8.1 4.5 | -16.8 1.8 245 17 9 8.0 4.4
19000 -15.4 4.3 270 23 12 8.1 4.5 | -15.6 3.9 245 16 8 8.0 4.4
18500 -14.3 6.3 270 24 12 6.2 3.4 | -14.5 5.9 245 16 8 7.0 3.9
18000 -13.4 7.9 270 25 13 6.4 3.5 | -13.5 7.7 250 17 9 7.1 3.9
17500 -12.5 9.5 270 26 14 5.8 3.2 | -12.4 9.7 255 18 9 7.0 3.8
17000 -11.7 10.9 265 28 15 5.7 3.1 | -11.4 11.5 255 21 11 6.9 3.8
16500 -10.8 12.6 265 30 15 6.0 3.3 | -10.4 13.3 255 24 12 7.0 3.8
16000 -9.8 14.4 265 31 16 7.5 4.1 | -9.4 15.1 255 26 13 7.1 3.9
15500 -8.8 16.2 260 32 17 7.2 4.0 | -8.4 16.9 260 27 14 7.0 3.8
15000 -7.5 18.5 260 32 17 9.7 5.3 | -7.2 19.0 260 28 15 8.8 4.8
14500 -6.1 21.0 260 32 17 9.5 5.2 | -5.9 21.4 260 29 15 8.6 4.7
14000 -4.7 23.5 260 32 16 9.2 5.1 | -4.6 23.7 260 28 15 9.7 5.3
13500 -3.4 25.9 260 30 16 9.2 5.1 | -3.1 26.4 260 27 14 9.8 5.4
13000 -2.0 28.4 260 29 15 9.0 4.9 | -1.7 28.9 255 26 13 10.4 5.7
12500 -0.8 30.6 255 27 14 7.7 4.2 | -0.2 31.6 255 24 12 8.1 4.4
12000 0.3 32.5 255 25 13 3.3 1.8 | 0.9 33.6 250 23 12 4.2 2.3
11750 0.3 32.5 255 24 12 -1.1 -0.6 | 1.0 33.8 250 22 11 1.0 0.6
11500 0.2 32.4 250 22 12 -0.3 -0.1 | 1.1 34.0 245 21 11 -0.5 -0.3
11250 0.2 32.4 245 21 11 0.2 0.1 | 0.8 33.4 240 20 10 -4.1 -2.2
11000 0.1 32.2 240 20 10 -4.2 -2.3 | 0.4 32.7 235 19 10 -7.0 -3.8
10750 -0.5 31.1 235 18 9 -8.9 -4.9 | -0.3 31.5 225 17 9 -9.2 -5.1
10500 -1.1 30.0 230 17 9 -6.5 -3.6 | -1.0 30.2 215 16 8 -9.0 -5.0
10250 -1.7 28.9 225 15 8 -11.3 -6.2 | -1.7 28.9 200 15 8 -7.5 -4.1
10000 -2.6 27.3 215 14 7 -6.6 -3.6 | -1.9 28.6 185 15 8 3.6 2.0
9750 -2.6 27.3 210 12 6 1.7 0.9 | -1.3 29.7 180 15 8 10.1 5.5
9500 -2.7 27.1 200 11 5 -1.4 -0.8 | -0.6 30.9 180 15 8 8.0 4.4
9250 -2.7 27.1 190 9 5 2.9 1.6 | -0.0 32.0 175 15 8 9.6 5.3
9000 -2.2 28.0 185 9 5 8.6 4.7 | 0.8 33.4 170 15 8 10.4 5.7
8750 -1.6 29.1 175 9 4 9.0 5.0 | 1.5 34.7 170 15 8 10.1 5.5
8500 -0.9 30.4 170 8 4 9.0 4.9 | 2.3 36.1 170 15 8 9.9 5.4
8250 -0.3 31.5 160 8 4 8.7 4.8 | 3.0 37.4 170 15 8 11.0 6.0
8000 0.6 33.1 160 8 4 15.0 8.3 | 4.1 39.4 170 15 8 20.1 11.1
7750 2.1 35.8 160 8 4 26.2 14.4 | 6.1 43.0 165 14 7 31.6 17.4
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
05/04/2024 at 1500 MDT | 05/04/2024 at 1800 MDT
|
CAPE... 0.0 LI... +1.0 | CAPE... 0.0 LI... -0.4
CINH... 0.0 K Index... +7.9 | CINH... 0.0 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 -55.5 -67.9 250 38 20 0.9 0.5 | -55.7 -68.3 250 31 16 1.5 0.8
45000 -54.4 -65.9 250 41 21 -2.7 -1.5 | -53.7 -64.7 255 32 16 -2.6 -1.4
40000 -59.4 -74.9 245 34 18 -3.1 -1.7 | -58.6 -73.5 255 33 17 -3.1 -1.7
38000 -58.0 -72.4 245 33 17 5.2 2.8 | -57.4 -71.3 255 31 16 4.6 2.5
36000 -54.9 -66.8 245 33 17 5.2 2.8 | -54.6 -66.3 255 29 15 4.5 2.5
34000 -51.3 -60.3 245 32 17 7.2 4.0 | -51.5 -60.7 260 28 15 6.8 3.7
32000 -47.0 -52.6 240 32 17 7.3 4.0 | -47.4 -53.3 260 29 15 6.8 3.7
30000 -42.6 -44.7 240 31 16 7.6 4.2 | -42.9 -45.2 260 29 15 8.7 4.8
29000 -40.3 -40.5 240 28 15 7.6 4.1 | -40.3 -40.5 255 28 14 8.7 4.8
28000 -38.0 -36.4 240 26 13 7.6 4.1 | -37.7 -35.9 255 26 13 8.7 4.8
27000 -35.7 -32.3 240 24 12 8.1 4.5 | -35.1 -31.2 255 24 13 8.3 4.6
26000 -33.3 -27.9 240 22 12 8.2 4.5 | -32.6 -26.7 255 22 12 8.3 4.6
25000 -30.8 -23.4 240 21 11 8.2 4.5 | -29.6 -21.3 250 20 10 8.3 4.6
24000 -27.7 -17.9 240 19 10 8.5 4.7 | -27.1 -16.8 250 18 9 7.7 4.2
23000 -25.2 -13.4 240 18 9 8.5 4.7 | -24.8 -12.6 250 17 9 7.8 4.3
22000 -22.6 -8.7 240 17 9 8.5 4.6 | -22.5 -8.5 250 15 8 7.8 4.3
21000 -20.2 -4.4 240 17 9 7.4 4.0 | -20.2 -4.4 250 14 7 7.5 4.1
20000 -18.0 -0.4 245 16 8 7.4 4.1 | -18.0 -0.4 245 13 7 7.6 4.2
19500 -16.9 1.6 250 16 8 7.4 4.1 | -16.9 1.6 240 13 7 7.6 4.2
19000 -15.8 3.6 250 16 8 7.4 4.1 | -15.8 3.6 240 13 7 7.6 4.2
18500 -14.7 5.5 255 16 8 7.7 4.2 | -14.6 5.7 235 13 7 7.9 4.3
18000 -13.5 7.7 260 16 8 7.7 4.2 | -13.5 7.7 230 13 7 7.9 4.3
17500 -12.4 9.7 265 16 8 7.9 4.3 | -12.3 9.9 220 14 7 8.1 4.5
17000 -11.2 11.8 270 17 9 8.1 4.4 | -11.1 12.0 215 14 7 8.3 4.5
16500 -10.0 14.0 275 18 9 8.2 4.5 | -9.9 14.2 215 15 8 8.2 4.5
16000 -8.8 16.2 270 19 10 8.2 4.5 | -8.7 16.3 210 16 8 7.8 4.3
15500 -7.7 18.1 270 20 10 8.2 4.5 | -7.6 18.3 205 16 8 7.8 4.3
15000 -6.4 20.5 265 20 10 9.1 5.0 | -6.4 20.5 205 17 9 7.9 4.3
14500 -5.1 22.8 260 20 10 9.0 4.9 | -5.3 22.5 205 18 9 7.9 4.3
14000 -3.7 25.3 255 20 10 9.3 5.1 | -4.1 24.6 205 19 10 8.0 4.4
13500 -2.3 27.9 250 19 10 9.3 5.1 | -2.9 26.8 200 19 10 8.1 4.5
13000 -0.9 30.4 245 19 10 11.4 6.2 | -1.7 28.9 200 20 10 8.4 4.6
12500 0.6 33.1 240 19 10 7.7 4.2 | -0.6 30.9 200 21 11 5.6 3.0
12000 1.8 35.2 235 18 9 6.1 3.4 | 0.3 32.5 200 21 11 4.4 2.4
11750 2.1 35.8 230 18 9 4.5 2.5 | 0.5 32.9 200 21 11 2.5 1.4
11500 2.5 36.5 225 18 9 3.2 1.8 | 0.7 33.3 205 21 11 2.8 1.6
11250 2.6 36.7 225 18 9 2.8 1.5 | 0.9 33.6 205 21 11 3.1 1.7
11000 2.7 36.9 220 18 9 -2.2 -1.2 | 1.1 34.0 205 22 11 2.2 1.2
10750 2.2 36.0 210 18 9 -8.0 -4.4 | 1.2 34.2 200 23 12 1.1 0.6
10500 1.7 35.1 200 18 9 -6.1 -3.4 | 1.3 34.3 200 23 12 1.3 0.7
10250 1.1 34.0 190 18 9 -9.5 -5.2 | 1.4 34.5 195 24 12 2.3 1.3
10000 0.5 32.9 185 19 10 0.5 0.3 | 1.7 35.1 190 24 12 6.2 3.4
9750 1.2 34.2 180 19 10 10.8 5.9 | 2.3 36.1 190 24 12 8.5 4.7
9500 1.8 35.2 175 19 10 7.7 4.2 | 2.9 37.2 185 24 12 7.6 4.2
9250 2.4 36.3 170 19 10 9.9 5.4 | 3.5 38.3 185 23 12 9.2 5.1
9000 3.2 37.8 170 19 10 10.4 5.7 | 4.3 39.7 180 23 12 10.2 5.6
8750 4.0 39.2 170 19 10 9.9 5.4 | 5.0 41.0 180 23 12 9.7 5.3
8500 4.7 40.5 165 19 10 9.4 5.2 | 5.7 42.3 180 23 12 9.4 5.2
8250 5.4 41.7 165 19 10 11.8 6.5 | 6.5 43.7 175 22 12 11.1 6.1
8000 6.6 43.9 165 18 10 21.2 11.6 | 8.7 47.7 175 19 10 17.6 9.7
7750 8.6 47.5 165 17 9 29.1 15.9 | 10.0 50.0 175 16 8 15.5 8.5
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
________________________________________________________________________________
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.
042613