Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
427
UXUS97 KPUB 271222
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0622 MDT Saturday, April 27, 2024
This forecast is for the Air Force Academy for Saturday, April 27, 2024:
If the trigger temperature of 45.6 F/7.5 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 9312 ft MSL (1631 ft AGL)
Forecast maximum temperature................... 39.0 F/4.3 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7890 ft MSL (209 ft AGL)
Thermal soaring outlook for Sunday 04/28....... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:05:06 / 19:48:30 MDT
Total possible sunshine........... 13 hr 43 min 24 sec (823 min 24 sec)
Altitude of sun at 12:56:48 MDT... 65.19 degrees
Upper air data from numerical model forecast valid on 04/27/2024 at 0600 MDT
Freezing level.................. 8160 ft MSL (479 ft AGL)
Convective condensation level... 11455 ft MSL (3774 ft AGL)
Lifted condensation level....... 10112 ft MSL (2431 ft AGL)
Lifted index.................... +4.9
K index......................... +20.4
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 -52.1 -61.8 220 28 14 1.5 0.8 M M M M M
45000 -49.7 -57.5 215 27 14 1.1 0.6 M M M M M
40000 -48.6 -55.5 210 35 18 0.8 0.4 M M M M M
38000 -49.8 -57.6 205 31 16 -6.6 -3.6 M M M M M
36000 -53.7 -64.7 165 23 12 -6.6 -3.6 M M M M M
34000 -57.7 -71.9 125 28 15 0.8 0.4 M M M M M
32000 -52.1 -61.8 125 29 15 9.5 5.2 M M M M M
30000 -45.6 -50.1 120 31 16 9.3 5.1 22.1 71.8 14.0 M M
29000 -42.8 -45.0 120 30 16 9.4 5.2 21.9 71.3 14.0 M M
28000 -40.0 -40.0 125 30 16 9.4 5.2 21.7 71.1 14.1 M M
27000 -37.2 -35.0 125 30 16 9.3 5.1 21.7 71.1 14.3 M M
26000 -34.7 -30.5 125 29 15 7.8 4.3 21.0 69.9 13.9 M M
25000 -32.4 -26.3 130 27 14 7.9 4.3 20.3 68.6 13.4 M M
24000 -30.0 -22.0 130 26 13 7.9 4.3 19.7 67.5 13.1 M M
23000 -27.8 -18.0 135 25 13 7.5 4.1 18.9 66.0 12.5 M M
22000 -25.5 -13.9 140 24 12 7.5 4.1 18.1 64.6 12.0 M M
21000 -23.3 -9.9 145 23 12 7.5 4.1 17.4 63.3 11.5 M M
20000 -21.2 -6.2 145 22 12 7.2 3.9 16.5 61.6 10.8 M M
19500 -20.1 -4.2 150 22 11 7.2 3.9 16.0 60.8 10.4 M M
19000 -19.0 -2.2 150 22 11 7.2 3.9 15.6 60.0 10.1 M M
18500 -18.0 -0.4 155 22 11 7.2 4.0 15.2 59.3 9.8 M M
18000 -16.9 1.6 155 21 11 6.8 3.7 14.7 58.5 9.4 M M
17500 -15.9 3.4 155 21 11 6.8 3.8 14.2 57.6 9.0 M M
17000 -14.9 5.2 155 21 11 7.2 3.9 13.8 56.8 8.6 M M
16500 -13.8 7.2 160 21 11 7.3 4.0 13.4 56.0 8.3 M M
16000 -12.8 9.0 160 20 11 7.1 3.9 13.0 55.3 7.9 M M
15500 -11.8 10.8 160 20 10 6.4 3.5 12.4 54.4 7.5 M M
15000 -10.8 12.6 160 20 10 6.5 3.5 11.9 53.4 7.0 M M
14500 -9.9 14.2 160 19 10 6.5 3.6 11.4 52.5 6.5 M M
14000 -8.9 16.0 160 19 10 6.5 3.5 10.9 51.5 6.0 M M
13500 -7.9 17.8 160 18 9 7.8 4.3 10.4 50.8 5.6 M M
13000 -6.8 19.8 160 17 9 9.0 4.9 10.1 50.2 5.3 M M
12500 -6.2 20.8 155 17 9 2.3 1.3 9.2 48.6 4.5 M M
12000 -5.3 22.5 155 16 8 5.4 3.0 8.6 47.5 3.9 M M
11750 -4.3 24.3 155 15 8 7.2 4.0 8.2 46.7 3.5 M M
11500 -3.9 25.0 155 14 7 5.2 2.8 7.9 46.2 3.2 M M
11250 -3.5 25.7 155 14 7 4.8 2.6 7.5 45.5 2.8 M M
11000 -3.2 26.2 155 13 7 4.9 2.7 7.1 44.8 2.4 M M
10750 -2.8 27.0 155 13 7 5.3 2.9 6.8 44.2 2.1 M M
10500 -2.4 27.7 150 12 6 5.2 2.8 6.4 43.6 1.7 M M
10250 -2.1 28.2 150 11 6 5.0 2.7 6.1 42.9 1.4 M M
10000 -1.7 28.9 150 11 6 4.8 2.7 5.7 42.2 1.0 M M
9750 -1.4 29.5 150 10 5 4.3 2.3 5.3 41.5 0.6 M M
9500 -1.1 30.0 155 9 5 4.2 2.3 4.9 40.8 0.2 M M
9250 -0.8 30.6 160 9 5 5.3 2.9 4.5 40.0 -0.2 164 0.8
9000 -0.4 31.3 165 9 4 3.6 2.0 4.1 39.4 -0.6 146 0.7
8750 -0.3 31.5 180 8 4 1.3 0.7 3.5 38.3 -1.2 135 0.7
8500 -0.2 31.6 195 9 4 1.4 0.8 2.9 37.2 -1.8 124 0.6
8250 -0.0 32.0 210 9 5 2.9 1.6 2.3 36.1 -2.4 112 0.6
8000 0.3 32.5 215 8 4 4.2 2.3 1.8 35.3 -2.9 97 0.5
7750 0.3 32.5 225 5 3 -7.9 -4.4 1.1 34.0 -3.6 89 0.5
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 * * * * * *
04/27/2024 at 0900 MDT | 04/27/2024 at 1200 MDT
|
CAPE... +95.8 LI... -1.4 | CAPE... +1.3 LI... -0.7
CINH... -73.2 K Index... +17.7 | CINH... -0.5 K Index... +21.7
|
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 -51.3 -60.3 210 26 13 2.1 1.1 | -52.1 -61.8 210 25 13 2.0 1.1
45000 -48.0 -54.4 205 25 13 1.1 0.6 | -49.0 -56.2 195 27 14 1.3 0.7
40000 -48.6 -55.5 210 33 17 -0.4 -0.2 | -48.1 -54.6 205 34 18 0.6 0.3
38000 -49.1 -56.4 205 33 17 -1.9 -1.0 | -48.1 -54.6 205 34 17 -1.1 -0.6
36000 -50.2 -58.4 185 27 14 -1.9 -1.0 | -48.7 -55.7 195 28 14 -1.1 -0.6
34000 -51.4 -60.5 160 26 13 0.9 0.5 | -49.4 -56.9 175 22 11 0.4 0.2
32000 -49.4 -56.9 125 26 13 3.4 1.9 | -48.6 -55.5 100 19 10 1.5 0.8
30000 -47.3 -53.1 105 33 17 6.3 3.5 | -47.6 -53.7 065 37 19 5.6 3.1
29000 -45.0 -49.0 110 33 17 7.9 4.3 | -45.2 -49.4 065 31 16 8.0 4.4
28000 -42.6 -44.7 110 33 17 7.9 4.4 | -42.8 -45.0 060 26 13 8.0 4.4
27000 -40.2 -40.4 115 34 17 8.0 4.4 | -40.4 -40.7 050 21 11 8.1 4.4
26000 -38.0 -36.4 125 33 17 7.0 3.9 | -38.0 -36.4 050 17 9 7.8 4.3
25000 -35.9 -32.6 130 33 17 7.0 3.8 | -35.7 -32.3 055 14 7 7.8 4.3
24000 -33.8 -28.8 140 33 17 7.0 3.9 | -33.4 -28.1 065 12 6 7.8 4.3
23000 -31.6 -24.9 150 33 17 7.7 4.2 | -31.0 -23.8 080 10 5 8.1 4.4
22000 -28.8 -19.8 155 31 16 7.8 4.3 | -28.6 -19.5 095 9 5 8.1 4.4
21000 -26.5 -15.7 165 31 16 7.9 4.3 | -25.6 -14.1 120 9 5 8.0 4.4
20000 -24.0 -11.2 170 30 15 8.1 4.4 | -23.4 -10.1 130 10 5 7.6 4.2
19500 -22.8 -9.0 175 30 15 8.1 4.4 | -22.2 -8.0 135 10 5 7.6 4.2
19000 -21.6 -6.9 180 30 15 8.1 4.4 | -21.1 -6.0 145 11 5 7.7 4.2
18500 -20.4 -4.7 185 30 15 8.0 4.4 | -20.0 -4.0 150 11 6 7.7 4.2
18000 -19.3 -2.7 185 29 15 7.7 4.2 | -18.9 -2.0 150 11 6 7.5 4.1
17500 -18.1 -0.6 185 27 14 7.8 4.3 | -17.7 0.1 155 12 6 7.5 4.1
17000 -17.0 1.4 185 25 13 7.3 4.0 | -16.6 2.1 155 12 6 7.6 4.2
16500 -16.0 3.2 185 23 12 7.3 4.0 | -15.5 4.1 155 13 6 7.6 4.2
16000 -15.0 5.0 185 21 11 7.8 4.3 | -14.4 6.1 155 13 7 7.7 4.2
15500 -13.7 7.3 190 19 10 8.4 4.6 | -13.2 8.2 155 13 7 7.9 4.3
15000 -12.5 9.5 195 17 9 8.5 4.7 | -12.1 10.2 150 14 7 7.9 4.3
14500 -11.2 11.8 195 17 9 9.0 4.9 | -11.0 12.2 145 14 7 7.1 3.9
14000 -9.9 14.2 190 17 9 8.9 4.9 | -10.0 14.0 140 15 8 7.2 4.0
13500 -8.6 16.5 190 18 9 9.6 5.3 | -8.9 16.0 135 16 8 6.8 3.7
13000 -7.2 19.0 185 19 10 10.8 5.9 | -8.0 17.6 130 17 9 6.0 3.3
12500 -6.4 20.5 185 19 10 4.1 2.2 | -6.6 20.1 125 19 10 8.7 4.8
12000 -5.1 22.8 185 18 10 7.6 4.1 | -5.9 21.4 125 20 10 4.8 2.7
11750 -4.5 23.9 185 18 9 10.6 5.8 | -5.6 21.9 125 20 10 6.1 3.3
11500 -3.6 25.5 190 16 8 10.0 5.5 | -5.1 22.8 120 20 10 7.1 3.9
11250 -3.1 26.4 190 15 8 6.5 3.6 | -4.6 23.7 120 19 10 5.6 3.1
11000 -2.6 27.3 190 14 7 6.9 3.8 | -4.2 24.4 120 19 10 5.5 3.0
10750 -2.1 28.2 195 12 6 6.8 3.8 | -3.8 25.2 120 18 9 5.3 2.9
10500 -1.5 29.3 190 10 5 7.1 3.9 | -3.5 25.7 120 16 8 4.9 2.7
10250 -1.0 30.2 190 7 4 5.7 3.1 | -3.1 26.4 125 14 7 5.0 2.8
10000 -0.7 30.7 185 6 3 4.9 2.7 | -2.7 27.1 120 13 7 5.5 3.0
9750 -0.4 31.3 180 5 3 4.4 2.4 | -2.4 27.7 120 12 6 4.6 2.5
9500 -0.1 31.8 160 3 2 3.1 1.7 | -2.1 28.2 120 10 5 3.4 1.8
9250 0.1 32.2 120 3 1 3.1 1.7 | -1.8 28.8 115 8 4 3.7 2.0
9000 0.3 32.5 085 3 2 3.6 2.0 | -1.5 29.3 100 7 3 5.4 3.0
8750 0.5 32.9 070 5 2 2.8 1.5 | -1.1 30.0 080 6 3 3.6 2.0
8500 0.7 33.3 060 6 3 1.8 1.0 | -1.0 30.2 055 6 3 1.3 0.7
8250 0.9 33.6 055 7 4 4.6 2.5 | -0.9 30.4 035 7 4 1.7 0.9
8000 1.5 34.7 055 7 3 13.9 7.6 | -0.7 30.7 020 8 4 4.1 2.3
7750 2.7 36.9 040 5 2 18.2 10.0 | -0.2 31.6 010 8 4 9.9 5.4
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
04/27/2024 at 1500 MDT | 04/27/2024 at 1800 MDT
|
CAPE... +4.8 LI... -1.5 | CAPE... +1.4 LI... +2.1
CINH... 0.0 K Index... +19.6 | CINH... 0.0 K Index... +13.4
|
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 -51.9 -61.4 215 24 12 1.5 0.8 | -52.1 -61.8 215 21 11 1.5 0.8
45000 -49.7 -57.5 205 31 16 1.1 0.6 | -49.9 -57.8 220 27 14 1.1 0.6
40000 -48.8 -55.8 215 33 17 0.6 0.3 | -49.2 -56.6 220 24 12 0.5 0.2
38000 -48.6 -55.5 215 32 17 -0.5 -0.3 | -49.2 -56.6 215 22 11 -1.0 -0.5
36000 -49.0 -56.2 210 27 14 -0.5 -0.3 | -49.9 -57.8 210 19 10 -1.0 -0.5
34000 -49.3 -56.7 205 23 12 0.6 0.3 | -50.4 -58.7 205 17 9 0.8 0.4
32000 -48.4 -55.1 180 4 2 1.4 0.8 | -49.4 -56.9 200 10 5 1.7 0.9
30000 -47.5 -53.5 035 16 8 5.2 2.9 | -48.2 -54.8 170 3 2 6.6 3.6
29000 -45.2 -49.4 020 14 7 7.5 4.1 | -45.8 -50.4 235 2 1 8.1 4.5
28000 -43.0 -45.4 005 13 7 7.5 4.1 | -43.3 -45.9 275 4 2 8.2 4.5
27000 -40.8 -41.4 350 14 7 7.5 4.1 | -40.9 -41.6 285 7 4 8.1 4.4
26000 -38.3 -36.9 340 13 7 8.5 4.7 | -38.3 -36.9 275 8 4 9.0 5.0
25000 -35.8 -32.4 330 11 6 8.5 4.7 | -35.6 -32.1 260 9 5 9.0 5.0
24000 -33.3 -27.9 320 9 5 8.5 4.7 | -32.9 -27.2 250 11 5 9.0 5.0
23000 -30.8 -23.4 305 7 4 7.7 4.2 | -30.2 -22.4 245 11 6 8.7 4.8
22000 -28.0 -18.4 285 4 2 7.7 4.2 | -27.7 -17.9 240 10 5 8.7 4.8
21000 -25.7 -14.3 245 3 2 7.7 4.2 | -24.4 -11.9 240 10 5 8.5 4.7
20000 -23.4 -10.1 220 5 2 7.6 4.2 | -22.0 -7.6 240 9 5 8.3 4.5
19500 -22.3 -8.1 210 6 3 7.6 4.2 | -20.7 -5.3 235 9 4 8.3 4.6
19000 -21.2 -6.2 205 7 3 7.6 4.2 | -19.5 -3.1 235 8 4 8.3 4.6
18500 -20.0 -4.0 205 8 4 7.7 4.2 | -18.3 -0.9 235 8 4 8.2 4.5
18000 -18.9 -2.0 200 9 4 8.0 4.4 | -17.1 1.2 230 7 4 7.8 4.3
17500 -17.7 0.1 195 9 5 8.0 4.4 | -15.9 3.4 225 7 4 7.9 4.3
17000 -16.5 2.3 190 10 5 7.8 4.3 | -14.8 5.4 215 7 3 7.0 3.8
16500 -15.3 4.5 185 11 6 7.7 4.2 | -13.8 7.2 205 7 3 7.0 3.8
16000 -14.2 6.4 180 12 6 7.3 4.0 | -12.7 9.1 195 7 3 6.9 3.8
15500 -13.2 8.2 175 13 7 6.6 3.6 | -11.7 10.9 190 8 4 6.9 3.8
15000 -12.2 10.0 175 15 8 6.6 3.6 | -10.7 12.7 185 8 4 6.9 3.8
14500 -11.3 11.7 170 16 8 6.5 3.5 | -9.7 14.5 185 9 5 6.8 3.7
14000 -10.4 13.3 170 17 9 6.3 3.5 | -8.6 16.5 190 10 5 6.8 3.7
13500 -9.4 15.1 165 17 9 8.3 4.6 | -7.7 18.1 190 10 5 6.4 3.5
13000 -8.2 17.2 155 16 8 7.0 3.8 | -6.7 19.9 190 10 5 6.1 3.3
12500 -6.5 20.3 150 16 8 11.9 6.6 | -5.7 21.7 195 9 5 6.0 3.3
12000 -5.6 21.9 130 18 9 6.1 3.4 | -5.3 22.5 200 8 4 3.6 2.0
11750 -5.2 22.6 125 19 10 7.3 4.0 | -5.1 22.8 200 7 4 2.2 1.2
11500 -4.6 23.7 115 21 11 6.2 3.4 | -5.0 23.0 195 5 2 1.8 1.0
11250 -4.4 24.1 110 21 11 1.5 0.8 | -4.9 23.2 150 2 1 3.2 1.8
11000 -4.3 24.3 105 21 11 0.8 0.5 | -4.7 23.5 090 4 2 3.2 1.8
10750 -4.2 24.4 095 22 11 0.8 0.4 | -4.5 23.9 070 6 3 4.2 2.3
10500 -4.2 24.4 090 21 11 0.2 0.1 | -4.1 24.6 060 10 5 6.7 3.7
10250 -4.2 24.4 075 21 11 0.5 0.3 | -3.6 25.5 055 13 7 3.7 2.0
10000 -4.1 24.6 070 20 10 0.8 0.4 | -3.5 25.7 050 15 8 0.7 0.4
9750 -4.0 24.8 060 19 10 0.8 0.4 | -3.5 25.7 045 17 9 0.8 0.4
9500 -4.0 24.8 050 19 10 0.6 0.4 | -3.4 25.9 030 18 9 -0.5 -0.3
9250 -3.9 25.0 040 19 10 1.4 0.8 | -3.4 25.9 020 19 10 0.8 0.4
9000 -3.7 25.3 030 20 10 3.6 2.0 | -3.3 26.1 015 21 11 4.0 2.2
8750 -3.4 25.9 020 20 10 5.0 2.7 | -2.9 26.8 005 22 11 4.3 2.4
8500 -3.0 26.6 010 19 10 5.1 2.8 | -2.7 27.1 355 22 11 3.1 1.7
8250 -2.7 27.1 360 19 10 4.7 2.6 | -2.4 27.7 350 23 12 3.3 1.8
8000 -2.3 27.9 350 19 10 7.7 4.3 | -2.1 28.2 340 24 12 7.7 4.2
7750 -0.6 30.9 345 12 6 5.8 3.2 | -1.2 29.8 340 20 10 15.4 8.4
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
________________________________________________________________________________
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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