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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 211232
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0632 MDT Sunday, April 21, 2024
This forecast is for the Air Force Academy for Sunday, April 21, 2024:
If the trigger temperature of 46.6 F/8.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 683 ft/min (3.5 m/s)
Maximum height of thermals.................. 17287 ft MSL (9695 ft AGL)
Forecast maximum temperature................... 56.0 F/13.8 C
Time of trigger temperature.................... 1145 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Overcast opaque high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 15198 ft MSL (7606 ft AGL)
Thermal soaring outlook for Monday 04/22....... Poor
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:12:59 / 19:42:40 MDT
Total possible sunshine........... 13 hr 29 min 41 sec (809 min 41 sec)
Altitude of sun at 12:57:50 MDT... 63.24 degrees
Upper air data from numerical model forecast valid on 04/21/2024 at 0600 MDT
Freezing level.................. 9162 ft MSL (1570 ft AGL)
Additional freezing level....... 9602 ft MSL (2010 ft AGL)
Convective condensation level... 12727 ft MSL (5135 ft AGL)
Lifted condensation level....... 14687 ft MSL (7095 ft AGL)
Lifted index.................... +1.4
K index......................... -16.4
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 -58.3 -72.9 295 52 27 0.9 0.5 M M M M M
45000 -56.9 -70.4 295 51 26 -0.6 -0.3 M M M M M
40000 -60.5 -76.9 295 59 30 -2.3 -1.3 M M M M M
38000 -59.1 -74.4 295 59 30 5.1 2.8 M M M M M
36000 -56.0 -68.8 305 57 29 5.1 2.8 M M M M M
34000 -52.5 -62.5 310 56 29 7.9 4.4 M M M M M
32000 -47.7 -53.9 310 55 28 8.0 4.4 M M M M M
30000 -42.8 -45.0 310 55 28 8.5 4.7 26.4 79.5 10.1 M M
29000 -40.2 -40.4 310 55 28 8.5 4.7 25.8 78.5 9.7 M M
28000 -37.7 -35.9 315 56 29 8.5 4.7 25.4 77.7 9.5 M M
27000 -35.1 -31.2 315 56 29 7.7 4.2 25.0 77.0 9.3 M M
26000 -32.9 -27.2 315 55 28 7.5 4.1 24.0 75.2 8.6 M M
25000 -30.6 -23.1 310 54 28 7.5 4.1 23.2 73.7 8.1 M M
24000 -28.4 -19.1 310 52 27 7.1 3.9 22.5 72.5 7.6 M M
23000 -25.9 -14.6 310 48 25 6.5 3.6 20.9 69.7 6.4 M M
22000 -24.0 -11.2 310 44 23 6.5 3.6 19.8 67.7 5.5 M M
21000 -22.1 -7.8 315 41 21 6.0 3.3 18.6 65.6 4.6 M M
20000 -20.3 -4.5 315 39 20 6.0 3.3 17.3 63.1 3.5 M M
19500 -19.4 -2.9 315 37 19 6.0 3.3 16.7 62.0 2.9 M M
19000 -18.4 -1.1 315 36 18 6.1 3.3 16.1 61.0 2.4 M M
18500 -17.6 0.3 315 35 18 4.6 2.5 15.3 59.6 1.8 M M
18000 -16.9 1.6 315 35 18 4.8 2.6 14.5 58.1 1.0 M M
17500 -16.2 2.8 315 34 18 4.3 2.4 13.7 56.6 0.3 M M
17000 -15.6 3.9 315 34 17 4.2 2.3 12.7 54.9 -0.6 861 4.4
16500 -15.0 5.0 315 33 17 4.8 2.6 11.8 53.2 -1.4 828 4.2
16000 -14.2 6.4 315 32 17 6.2 3.4 11.1 52.0 -2.1 789 4.0
15500 -13.3 8.1 315 31 16 6.2 3.4 10.6 51.0 -2.7 747 3.8
15000 -12.3 9.9 315 30 15 7.6 4.2 10.1 50.2 -3.2 703 3.6
14500 -11.2 11.8 315 29 15 7.5 4.1 9.7 49.5 -3.6 656 3.3
14000 -10.1 13.8 315 27 14 8.7 4.8 9.5 49.0 -3.9 606 3.1
13500 -8.8 16.2 315 25 13 8.8 4.8 9.3 48.7 -4.1 553 2.8
13000 -7.5 18.5 315 23 12 8.5 4.6 9.1 48.4 -4.4 501 2.5
12500 -6.3 20.7 320 20 10 9.2 5.1 8.9 48.1 -4.6 448 2.3
12000 -4.9 23.2 320 19 10 8.5 4.6 8.9 47.9 -4.7 393 2.0
11750 -4.3 24.3 320 18 9 8.2 4.5 8.7 47.7 -4.9 368 1.9
11500 -3.7 25.3 315 17 8 8.3 4.5 8.6 47.5 -5.0 342 1.7
11250 -3.1 26.4 315 16 8 7.9 4.4 8.5 47.3 -5.2 317 1.6
11000 -2.6 27.3 315 15 8 7.5 4.1 8.3 47.0 -5.4 293 1.5
10750 -2.0 28.4 315 14 7 7.4 4.1 8.2 46.7 -5.6 269 1.4
10500 -1.5 29.3 315 13 7 7.5 4.1 8.0 46.4 -5.8 246 1.2
10250 -1.0 30.2 315 12 6 7.4 4.1 7.8 46.1 -6.0 222 1.1
10000 -0.5 31.1 310 11 5 5.1 2.8 7.6 45.6 -6.3 200 1.0
9750 -0.2 31.6 310 10 5 3.0 1.6 7.1 44.8 -6.7 185 0.9
9500 0.0 32.0 310 10 5 5.1 2.8 6.6 43.9 -7.2 170 0.9
9250 0.3 32.5 305 9 5 -1.4 -0.8 6.2 43.1 -7.7 154 0.8
9000 -0.2 31.6 295 8 4 -7.7 -4.2 4.9 40.9 -8.9 161 0.8
8750 -0.7 30.7 275 7 4 -6.1 -3.3 3.7 38.7 -10.2 169 0.9
8500 -1.2 29.8 255 7 4 -5.8 -3.2 2.5 36.5 -11.4 176 0.9
8250 -1.5 29.3 235 8 4 -1.9 -1.1 1.4 34.6 -12.5 178 0.9
8000 -1.4 29.5 220 7 4 2.8 1.6 0.7 33.3 -13.2 169 0.9
7750 -1.1 30.0 200 6 3 5.0 2.8 0.3 32.6 -13.7 153 0.8
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 * * * * * *
04/21/2024 at 0900 MDT | 04/21/2024 at 1200 MDT
|
CAPE... +5.8 LI... +3.7 | CAPE... +6.2 LI... +1.9
CINH... -1.1 K Index... -9.4 | CINH... -3.3 K Index... -7.8
|
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 -57.5 -71.5 295 49 25 0.7 0.4 | -57.0 -70.6 295 43 22 1.4 0.7
45000 -56.5 -69.7 300 51 26 -2.9 -1.6 | -55.1 -67.2 295 45 23 -3.9 -2.1
40000 -61.6 -78.9 300 55 28 -3.4 -1.9 | -61.4 -78.5 295 53 27 -4.2 -2.3
38000 -60.5 -76.9 300 55 28 5.8 3.2 | -60.6 -77.1 300 54 28 5.4 3.0
36000 -57.0 -70.6 310 54 28 5.8 3.2 | -57.4 -71.3 310 54 28 5.4 3.0
34000 -53.2 -63.8 315 54 28 8.1 4.4 | -53.1 -63.6 315 53 27 8.4 4.6
32000 -47.7 -53.9 315 53 28 8.1 4.5 | -48.0 -54.4 315 51 26 8.4 4.6
30000 -42.8 -45.0 315 52 27 8.6 4.7 | -43.0 -45.4 320 48 25 8.5 4.7
29000 -40.2 -40.4 315 52 27 8.6 4.7 | -40.4 -40.7 320 47 24 8.5 4.7
28000 -37.6 -35.7 315 51 26 8.6 4.7 | -37.9 -36.2 320 46 24 8.5 4.7
27000 -35.1 -31.2 315 51 26 8.3 4.5 | -35.3 -31.5 320 45 23 8.4 4.6
26000 -32.6 -26.7 320 51 26 8.3 4.6 | -32.8 -27.0 325 45 23 8.5 4.6
25000 -30.1 -22.2 320 52 27 8.3 4.6 | -30.3 -22.5 325 45 23 8.5 4.6
24000 -27.7 -17.9 320 52 27 6.8 3.7 | -27.8 -18.0 325 45 23 7.4 4.0
23000 -25.8 -14.4 320 47 24 6.2 3.4 | -25.7 -14.3 325 43 22 7.1 3.9
22000 -24.0 -11.2 325 43 22 6.2 3.4 | -23.5 -10.3 325 41 21 7.1 3.9
21000 -22.1 -7.8 325 39 20 6.6 3.6 | -21.5 -6.7 325 38 20 5.9 3.3
20000 -19.6 -3.3 325 33 17 6.6 3.6 | -19.2 -2.6 325 33 17 6.1 3.3
19500 -18.6 -1.5 325 31 16 6.6 3.6 | -18.3 -0.9 325 31 16 6.1 3.3
19000 -17.7 0.1 325 29 15 6.6 3.6 | -17.4 0.7 320 29 15 6.5 3.6
18500 -16.7 1.9 325 27 14 6.7 3.7 | -16.3 2.7 320 27 14 7.6 4.2
18000 -15.7 3.7 325 24 12 6.8 3.7 | -15.2 4.6 320 26 13 7.7 4.2
17500 -14.8 5.4 325 22 11 4.6 2.5 | -14.1 6.6 320 25 13 6.9 3.8
17000 -14.1 6.6 325 22 11 4.3 2.3 | -13.1 8.4 320 25 13 6.8 3.7
16500 -13.5 7.7 325 22 12 4.1 2.2 | -12.0 10.4 325 26 13 6.1 3.3
16000 -12.9 8.8 325 23 12 3.9 2.1 | -11.3 11.7 325 25 13 5.4 2.9
15500 -12.4 9.7 325 23 12 3.9 2.2 | -10.5 13.1 325 24 13 5.3 2.9
15000 -11.7 10.9 325 23 12 5.1 2.8 | -9.7 14.5 325 24 12 5.0 2.7
14500 -11.0 12.2 320 22 11 4.8 2.6 | -9.0 15.8 320 23 12 5.0 2.7
14000 -10.1 13.8 320 21 11 7.9 4.3 | -8.2 17.2 320 22 11 5.8 3.2
13500 -9.0 15.8 320 20 10 7.7 4.2 | -7.4 18.7 315 21 11 6.0 3.3
13000 -7.9 17.8 315 19 10 8.1 4.4 | -6.6 20.1 310 19 10 5.8 3.2
12500 -6.7 19.9 320 18 9 8.7 4.8 | -5.7 21.7 300 16 8 8.1 4.5
12000 -5.4 22.3 320 17 9 9.0 4.9 | -4.4 24.1 300 14 7 8.7 4.8
11750 -4.8 23.4 320 16 8 9.2 5.1 | -3.8 25.2 300 13 7 8.9 4.9
11500 -4.1 24.6 320 16 8 8.4 4.6 | -3.2 26.2 300 12 6 8.2 4.5
11250 -3.5 25.7 320 16 8 7.4 4.1 | -2.6 27.3 300 11 6 7.8 4.3
11000 -3.0 26.6 320 15 8 7.8 4.3 | -2.0 28.4 300 10 5 8.3 4.5
10750 -2.4 27.7 320 14 7 7.9 4.4 | -1.4 29.5 300 9 5 8.3 4.6
10500 -1.8 28.8 320 14 7 8.2 4.5 | -0.8 30.6 300 8 4 8.4 4.6
10250 -1.2 29.8 320 13 7 7.2 3.9 | -0.2 31.6 305 6 3 8.6 4.7
10000 -0.8 30.6 325 12 6 6.5 3.5 | 0.5 32.9 310 6 3 8.4 4.6
9750 -0.3 31.5 325 11 5 6.8 3.7 | 1.1 34.0 315 4 2 8.2 4.5
9500 0.2 32.4 325 9 5 7.4 4.0 | 1.7 35.1 315 3 2 8.2 4.5
9250 0.6 33.1 325 8 4 2.9 1.6 | 2.2 36.0 325 2 1 5.9 3.3
9000 0.6 33.1 325 7 4 1.2 0.6 | 2.6 36.7 325 1 1 6.8 3.8
8750 0.9 33.6 320 6 3 4.6 2.5 | 3.2 37.8 360 1 0 9.2 5.0
8500 1.1 34.0 315 5 3 2.0 1.1 | 3.8 38.8 070 1 0 8.6 4.7
8250 1.0 33.8 300 4 2 -5.9 -3.3 | 4.4 39.9 105 1 1 8.3 4.5
8000 0.5 32.9 255 3 1 0.1 0.1 | 5.2 41.4 125 2 1 14.7 8.1
7750 1.3 34.3 215 3 1 22.1 12.1 | 6.7 44.1 125 2 1 26.5 14.5
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
04/21/2024 at 1500 MDT | 04/21/2024 at 1800 MDT
|
CAPE... +10.1 LI... +1.0 | CAPE... +12.1 LI... +0.4
CINH... -1.0 K Index... -2.4 | CINH... -6.4 K Index... +6.4
|
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 -56.9 -70.4 295 40 21 0.8 0.5 | -58.3 -72.9 295 45 23 0.5 0.2
45000 -55.9 -68.6 295 43 22 -4.3 -2.3 | -57.9 -72.2 300 50 26 -3.6 -2.0
40000 -62.7 -80.9 305 52 27 -4.6 -2.5 | -62.9 -81.2 315 53 27 -3.5 -1.9
38000 -61.5 -78.7 305 53 27 6.6 3.6 | -61.3 -78.3 315 53 27 6.5 3.6
36000 -57.6 -71.7 310 54 28 6.6 3.6 | -57.4 -71.3 315 53 27 6.5 3.6
34000 -52.7 -62.9 315 53 27 8.6 4.7 | -52.5 -62.5 315 52 27 8.4 4.6
32000 -47.6 -53.7 315 50 26 8.5 4.7 | -47.5 -53.5 320 49 25 8.4 4.6
30000 -42.6 -44.7 315 46 24 8.0 4.4 | -42.4 -44.3 320 45 23 8.6 4.7
29000 -40.2 -40.4 315 44 23 8.0 4.4 | -39.8 -39.6 320 43 22 8.6 4.7
28000 -37.8 -36.0 315 41 21 8.0 4.4 | -37.3 -35.1 320 41 21 8.6 4.7
27000 -35.4 -31.7 315 39 20 8.3 4.6 | -34.8 -30.6 320 40 20 7.6 4.2
26000 -32.9 -27.2 320 38 20 8.3 4.5 | -32.5 -26.5 320 38 19 7.7 4.2
25000 -30.4 -22.7 320 37 19 8.3 4.5 | -30.2 -22.4 315 36 19 7.6 4.2
24000 -27.9 -18.2 320 36 19 8.4 4.6 | -27.9 -18.2 315 34 18 8.3 4.5
23000 -25.4 -13.7 325 37 19 8.4 4.6 | -25.4 -13.7 315 32 17 8.3 4.5
22000 -22.9 -9.2 325 37 19 8.4 4.6 | -22.9 -9.2 320 31 16 8.3 4.5
21000 -20.6 -5.1 325 36 19 6.1 3.3 | -20.5 -4.9 320 29 15 7.6 4.2
20000 -18.2 -0.8 325 34 17 6.3 3.5 | -17.6 0.3 320 29 15 7.7 4.2
19500 -17.3 0.9 320 33 17 6.3 3.5 | -16.4 2.5 320 29 15 7.7 4.2
19000 -16.3 2.7 320 32 16 6.2 3.4 | -15.3 4.5 320 29 15 7.1 3.9
18500 -15.4 4.3 320 31 16 5.8 3.2 | -14.4 6.1 320 29 15 6.1 3.3
18000 -14.6 5.7 320 30 15 5.8 3.2 | -13.5 7.7 315 29 15 6.2 3.4
17500 -13.7 7.3 320 29 15 6.4 3.5 | -12.6 9.3 315 28 15 6.2 3.4
17000 -12.7 9.1 315 28 14 6.5 3.5 | -11.7 10.9 305 27 14 6.4 3.5
16500 -11.8 10.8 315 27 14 6.8 3.7 | -10.8 12.6 300 26 14 7.3 4.0
16000 -10.8 12.6 310 26 13 7.2 4.0 | -9.7 14.5 295 25 13 7.9 4.3
15500 -9.7 14.5 310 25 13 7.4 4.1 | -8.6 16.5 285 24 12 8.3 4.5
15000 -8.7 16.3 305 23 12 7.5 4.1 | -7.2 19.0 285 23 12 9.6 5.2
14500 -7.7 18.1 295 20 10 7.6 4.2 | -5.8 21.6 280 23 12 9.5 5.2
14000 -6.5 20.3 285 18 9 8.9 4.9 | -4.5 23.9 280 22 11 9.1 5.0
13500 -5.2 22.6 280 17 9 8.8 4.8 | -3.1 26.4 280 20 10 9.3 5.1
13000 -4.0 24.8 275 15 8 8.2 4.5 | -1.9 28.6 275 17 9 8.1 4.5
12500 -2.8 27.0 270 12 6 8.0 4.4 | -0.8 30.6 275 14 7 7.6 4.2
12000 -1.7 28.9 265 10 5 6.2 3.4 | 0.3 32.5 270 12 6 6.8 3.7
11750 -1.3 29.7 265 9 4 6.0 3.3 | 0.8 33.4 265 11 6 6.4 3.5
11500 -0.9 30.4 260 7 4 6.0 3.3 | 1.2 34.2 255 10 5 7.5 4.1
11250 -0.5 31.1 250 6 3 5.6 3.1 | 1.8 35.2 255 10 5 6.9 3.8
11000 -0.1 31.8 245 5 3 5.3 2.9 | 2.2 36.0 245 9 5 3.5 1.9
10750 0.3 32.5 230 4 2 5.2 2.8 | 2.3 36.1 235 9 5 2.3 1.3
10500 0.7 33.3 215 4 2 5.3 2.9 | 2.5 36.5 225 10 5 2.9 1.6
10250 1.1 34.0 195 4 2 6.4 3.5 | 2.8 37.0 220 10 5 5.0 2.7
10000 1.6 34.9 180 4 2 5.8 3.2 | 3.2 37.8 210 11 6 3.9 2.1
9750 2.0 35.6 170 5 3 4.5 2.5 | 3.3 37.9 205 12 6 1.6 0.9
9500 2.3 36.1 160 6 3 5.2 2.8 | 3.4 38.1 200 13 7 2.4 1.3
9250 2.7 36.9 155 7 4 3.9 2.1 | 3.6 38.5 190 14 7 1.4 0.8
9000 2.9 37.2 160 8 4 6.0 3.3 | 3.7 38.7 190 14 7 4.6 2.5
8750 3.5 38.3 155 9 5 8.7 4.8 | 4.2 39.6 185 14 7 7.7 4.2
8500 4.1 39.4 155 9 5 8.3 4.5 | 4.7 40.5 180 14 7 6.7 3.7
8250 4.7 40.5 155 10 5 10.5 5.8 | 5.3 41.5 175 15 8 8.5 4.7
8000 5.7 42.3 155 10 5 17.2 9.5 | 6.0 42.8 175 14 7 12.7 7.0
7750 7.3 45.1 155 10 5 25.0 13.7 | 7.1 44.8 170 12 6 16.0 8.8
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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