Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
309
UXUS97 KBOU 270113
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1913 MDT Wednesday, June 26, 2024
This forecast is for Thursday, June 27, 2024:
If the trigger temperature of 84.7 F/29.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1113 ft/min (5.7 m/s)
Maximum height of thermals.................. 15576 ft MSL (10284 ft AGL)
Forecast maximum temperature................... 92.0 F/33.8 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ 1200 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10482 ft MSL (5190 ft AGL)
Thermal soaring outlook for Friday 06/28....... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 24766 ft MSL (19474 ft AGL)
Wave soaring outlook for Friday 06/28.......... Poor
Remarks...
Sunrise/Sunset.................... 05:33:46 / 20:31:43 MDT
Total possible sunshine........... 14 hr 57 min 57 sec (897 min 57 sec)
Altitude of sun at 13:02:44 MDT... 73.50 degrees
Upper air data from numerical model forecast valid on 06/27/2024 at 0600 MDT
Freezing level.................. 16829 ft MSL (11537 ft AGL)
Convective condensation level... 14858 ft MSL (9566 ft AGL)
Lifted condensation level....... 15184 ft MSL (9892 ft AGL)
Lifted index.................... -2.4
K index......................... +25.7
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 -65.4 -85.7 255 42 22 2.3 1.3 M M M M M
45000 -59.6 -75.3 250 55 28 6.5 3.5 M M M M M
40000 -49.6 -57.3 250 58 30 7.6 4.2 M M M M M
38000 -45.1 -49.2 255 55 28 7.6 4.2 M M M M M
36000 -40.5 -40.9 255 52 27 7.6 4.2 M M M M M
34000 -35.3 -31.5 255 44 23 7.8 4.3 M M M M M
32000 -30.6 -23.1 255 36 19 8.3 4.5 M M M M M
30000 -26.2 -15.2 260 33 17 7.3 4.0 50.0 122.0 12.7 M M
29000 -24.0 -11.2 260 32 16 7.3 4.0 49.1 120.5 12.1 M M
28000 -21.8 -7.2 265 31 16 7.0 3.9 48.3 118.9 11.6 M M
27000 -19.7 -3.5 265 30 15 7.1 3.9 47.1 116.8 10.8 M M
26000 -17.6 0.3 270 29 15 7.1 3.9 46.1 115.0 10.1 M M
25000 -15.6 3.9 270 28 14 7.0 3.9 45.2 113.4 9.5 M M
24000 -13.5 7.7 270 27 14 6.9 3.8 44.1 111.4 8.6 M M
23000 -11.5 11.3 270 26 14 6.9 3.8 43.0 109.5 7.8 M M
22000 -9.4 15.1 270 26 13 6.7 3.7 42.1 107.8 7.1 M M
21000 -7.6 18.3 275 24 12 6.2 3.4 40.7 105.3 6.0 M M
20000 -5.8 21.6 275 22 11 6.2 3.4 39.5 103.1 4.9 M M
19500 -4.9 23.2 275 21 11 6.2 3.4 38.9 102.0 4.4 M M
19000 -4.0 24.8 280 20 10 6.1 3.4 38.3 101.0 3.8 M M
18500 -3.2 26.2 280 19 10 6.1 3.4 37.7 99.8 3.3 M M
18000 -2.3 27.9 280 18 9 6.1 3.4 37.1 98.7 2.7 M M
17500 -1.4 29.5 280 17 9 6.1 3.3 36.4 97.6 2.2 M M
17000 -0.1 31.8 280 15 8 6.3 3.5 35.5 95.9 1.3 M M
16500 0.9 33.6 285 15 8 6.9 3.8 35.0 95.0 0.8 M M
16000 1.8 35.2 285 14 7 6.8 3.7 34.5 94.1 0.3 M M
15500 2.9 37.2 290 14 7 7.6 4.2 34.1 93.3 -0.1 896 4.6
15000 4.0 39.2 295 14 7 7.6 4.2 33.7 92.7 -0.5 848 4.3
14500 5.1 41.2 295 14 7 7.9 4.3 33.4 92.1 -0.9 801 4.1
14000 6.2 43.2 300 15 8 8.1 4.4 33.1 91.6 -1.2 751 3.8
13500 7.4 45.3 300 16 8 8.3 4.5 32.8 91.1 -1.5 701 3.6
13000 8.6 47.5 305 16 8 8.6 4.7 32.6 90.7 -1.7 650 3.3
12500 9.9 49.8 305 17 9 8.6 4.7 32.5 90.4 -1.9 597 3.0
12000 11.1 52.0 305 18 9 8.4 4.6 32.2 90.0 -2.2 546 2.8
11500 12.3 54.1 305 18 9 8.4 4.6 32.0 89.7 -2.4 494 2.5
11000 13.5 56.3 305 18 9 7.8 4.3 31.8 89.2 -2.7 444 2.3
10500 14.7 58.5 305 17 9 4.8 2.6 31.5 88.7 -3.0 393 2.0
10250 14.9 58.8 305 17 9 5.4 3.0 31.0 87.8 -3.5 379 1.9
10000 15.6 60.1 300 16 8 10.0 5.5 30.9 87.7 -3.6 352 1.8
9750 16.2 61.2 300 15 8 8.8 4.8 30.9 87.6 -3.7 325 1.6
9500 16.9 62.4 300 14 7 9.0 4.9 30.8 87.5 -3.7 298 1.5
9250 17.5 63.5 300 13 7 5.5 3.0 30.7 87.2 -3.9 273 1.4
9000 17.8 64.0 295 13 7 5.0 2.7 30.2 86.4 -4.3 257 1.3
8750 18.2 64.8 295 12 6 7.1 3.9 30.0 86.0 -4.6 235 1.2
8500 18.7 65.7 295 11 6 6.3 3.5 29.8 85.6 -4.9 214 1.1
8250 19.1 66.4 290 11 6 4.4 2.4 29.4 85.0 -5.2 195 1.0
8000 19.3 66.7 290 10 5 3.4 1.9 29.0 84.1 -5.7 180 0.9
7750 19.6 67.3 290 10 5 4.3 2.4 28.5 83.3 -6.2 165 0.8
7500 19.8 67.6 290 9 5 3.1 1.7 28.1 82.5 -6.7 150 0.8
7250 19.9 67.8 290 9 5 0.8 0.4 27.5 81.4 -7.4 140 0.7
7000 19.9 67.8 295 9 5 0.0 0.0 26.7 80.1 -8.1 133 0.7
6750 19.9 67.8 295 9 4 1.0 0.6 26.0 78.9 -8.9 126 0.6
6500 19.9 67.8 300 8 4 -0.5 -0.3 25.4 77.6 -9.7 120 0.6
6250 19.7 67.5 300 7 4 -2.5 -1.4 24.5 76.0 -10.6 118 0.6
6000 19.5 67.1 300 6 3 -1.8 -1.0 23.6 74.4 -11.6 117 0.6
5750 19.3 66.7 295 5 2 -2.5 -1.4 22.7 72.8 -12.6 116 0.6
5500 18.9 66.0 275 3 2 -7.1 -3.9 21.6 70.9 -13.7 121 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/27/2024 at 0900 MDT | 06/27/2024 at 1200 MDT
|
CAPE... +205.4 LI... -1.0 | CAPE... +497.9 LI... -2.2
CINH... -144.3 K Index... +28.9 | CINH... -38.4 K Index... +31.8
|
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 -64.9 -84.8 255 42 22 2.3 1.2 | -64.1 -83.4 250 44 23 3.3 1.8
45000 -59.5 -75.1 250 55 28 6.0 3.3 | -58.2 -72.8 250 59 30 5.1 2.8
40000 -50.0 -58.0 245 62 32 7.9 4.3 | -50.1 -58.2 245 71 37 7.6 4.2
38000 -45.2 -49.4 245 61 32 7.9 4.3 | -45.5 -49.9 245 70 36 7.6 4.1
36000 -40.5 -40.9 245 60 31 7.8 4.3 | -41.0 -41.8 240 69 35 7.5 4.1
34000 -35.6 -32.1 250 51 26 7.2 3.9 | -36.2 -33.2 240 59 30 7.1 3.9
32000 -31.3 -24.3 250 42 22 7.9 4.3 | -31.9 -25.4 240 50 26 7.9 4.3
30000 -27.0 -16.6 250 36 19 7.1 3.9 | -27.8 -18.0 245 41 21 6.9 3.8
29000 -24.9 -12.8 250 34 17 7.2 3.9 | -25.7 -14.3 245 36 19 6.9 3.8
28000 -22.8 -9.0 255 31 16 6.9 3.8 | -23.7 -10.7 245 32 17 6.9 3.8
27000 -20.8 -5.4 255 30 15 6.9 3.8 | -21.7 -7.1 250 31 16 6.9 3.8
26000 -18.8 -1.8 260 29 15 6.9 3.8 | -19.6 -3.3 250 29 15 7.0 3.8
25000 -16.7 1.9 260 27 14 6.9 3.8 | -17.6 0.3 255 28 14 7.0 3.8
24000 -14.6 5.7 265 27 14 7.1 3.9 | -15.5 4.1 255 27 14 6.8 3.7
23000 -12.5 9.5 265 27 14 7.2 3.9 | -13.5 7.7 260 26 13 6.8 3.8
22000 -10.4 13.3 270 27 14 7.0 3.8 | -11.5 11.3 260 25 13 6.9 3.8
21000 -8.6 16.5 270 25 13 6.3 3.4 | -9.4 15.1 265 24 12 7.3 4.0
20000 -6.8 19.8 270 23 12 6.3 3.5 | -7.3 18.9 265 24 12 7.3 4.0
19500 -5.9 21.4 275 22 11 6.3 3.5 | -6.2 20.8 270 23 12 7.4 4.0
19000 -5.0 23.0 275 21 11 6.4 3.5 | -5.2 22.6 270 23 12 6.6 3.6
18500 -4.1 24.6 275 20 10 6.4 3.5 | -4.2 24.4 270 23 12 6.5 3.6
18000 -3.1 26.4 275 19 10 6.5 3.6 | -3.3 26.1 270 23 12 6.6 3.6
17500 -1.7 28.9 275 17 9 6.8 3.7 | -1.8 28.8 270 22 11 7.2 3.9
17000 -0.7 30.7 275 16 8 7.0 3.8 | -0.8 30.6 270 22 11 7.4 4.0
16500 0.4 32.7 280 16 8 7.6 4.2 | 0.3 32.5 270 21 11 8.0 4.4
16000 1.5 34.7 280 15 8 7.6 4.2 | 1.5 34.7 270 20 10 8.0 4.4
15500 2.6 36.7 280 14 7 7.7 4.2 | 2.7 36.9 270 19 10 8.4 4.6
15000 3.7 38.7 285 14 7 7.7 4.2 | 3.9 39.0 275 18 9 8.4 4.6
14500 4.8 40.6 285 14 7 8.1 4.4 | 5.1 41.2 275 18 9 8.4 4.6
14000 6.0 42.8 290 13 7 8.2 4.5 | 6.4 43.5 280 17 9 8.4 4.6
13500 7.2 45.0 290 13 7 8.3 4.5 | 7.6 45.7 280 17 9 8.4 4.6
13000 8.4 47.1 290 13 7 8.3 4.5 | 8.8 47.8 280 17 9 8.4 4.6
12500 9.6 49.3 290 13 7 8.3 4.6 | 10.0 50.0 285 17 9 8.4 4.6
12000 10.9 51.6 290 13 7 8.5 4.6 | 11.3 52.3 285 17 9 8.7 4.8
11500 12.1 53.8 295 13 7 8.4 4.6 | 12.5 54.5 285 16 8 8.7 4.8
11000 13.2 55.8 295 13 7 6.9 3.8 | 13.7 56.7 285 15 8 7.4 4.1
10500 14.2 57.6 295 13 7 10.9 6.0 | 14.7 58.5 285 14 7 11.6 6.4
10250 15.2 59.4 295 13 7 11.8 6.5 | 15.8 60.4 285 14 7 12.6 6.9
10000 15.8 60.4 295 14 7 7.1 3.9 | 16.4 61.5 285 13 7 7.7 4.2
9750 16.4 61.5 295 14 7 8.4 4.6 | 17.1 62.8 285 13 7 9.1 5.0
9500 16.9 62.4 295 14 7 7.8 4.3 | 17.7 63.9 285 12 6 8.5 4.7
9250 17.5 63.5 295 14 7 6.4 3.5 | 18.3 64.9 285 11 6 7.3 4.0
9000 17.9 64.2 295 14 7 7.3 4.0 | 18.8 65.8 285 10 5 8.3 4.6
8750 18.5 65.3 295 14 7 8.8 4.9 | 19.5 67.1 285 10 5 9.9 5.4
8500 19.2 66.6 295 14 7 8.2 4.5 | 20.2 68.4 280 9 5 9.6 5.3
8250 19.7 67.5 295 14 7 6.4 3.5 | 20.9 69.6 280 8 4 6.5 3.6
8000 20.1 68.2 295 14 7 5.7 3.1 | 21.3 70.3 280 7 4 7.2 4.0
7750 20.6 69.1 295 13 7 6.9 3.8 | 22.0 71.6 280 6 3 10.4 5.7
7500 21.0 69.8 295 13 6 5.6 3.1 | 22.7 72.9 280 6 3 9.3 5.1
7250 21.3 70.3 290 12 6 3.0 1.6 | 23.3 73.9 280 5 3 7.7 4.2
7000 21.5 70.7 290 11 6 2.9 1.6 | 23.9 75.0 290 5 2 8.3 4.5
6750 21.8 71.2 285 10 5 5.3 2.9 | 24.6 76.3 290 4 2 12.2 6.7
6500 22.2 72.0 280 8 4 6.3 3.4 | 25.6 78.1 285 4 2 11.8 6.5
6250 22.6 72.7 275 6 3 6.3 3.5 | 26.4 79.5 290 4 2 9.4 5.2
6000 23.1 73.6 260 5 2 5.9 3.3 | 27.1 80.8 295 4 2 9.3 5.1
5750 23.6 74.5 245 4 2 10.2 5.6 | 27.8 82.0 300 4 2 10.4 5.7
5500 24.6 76.3 245 3 2 19.1 10.5 | 28.7 83.7 290 4 2 16.5 9.0
06/27/2024 at 1500 MDT | 06/27/2024 at 1800 MDT
|
CAPE... +510.9 LI... -2.2 | CAPE... +380.1 LI... -2.0
CINH... -121.0 K Index... +31.8 | CINH... -58.5 K Index... +32.0
|
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 -64.1 -83.4 250 47 24 3.5 1.9 | -64.9 -84.8 250 45 23 2.4 1.3
45000 -58.2 -72.8 245 61 32 4.6 2.5 | -59.3 -74.7 250 55 28 5.8 3.2
40000 -50.6 -59.1 240 76 39 8.1 4.4 | -50.2 -58.4 245 64 33 7.9 4.3
38000 -45.7 -50.3 240 72 37 8.1 4.4 | -45.5 -49.9 245 60 31 7.8 4.3
36000 -40.9 -41.6 235 68 35 8.0 4.4 | -40.8 -41.4 250 56 29 7.8 4.3
34000 -36.3 -33.3 235 58 30 7.6 4.2 | -36.4 -33.5 250 50 26 7.3 4.0
32000 -31.1 -24.0 230 46 24 8.4 4.6 | -31.4 -24.5 250 43 22 8.3 4.6
30000 -26.8 -16.2 235 41 21 7.3 4.0 | -26.9 -16.4 250 42 21 7.6 4.2
29000 -24.6 -12.3 235 39 20 7.3 4.0 | -24.6 -12.3 245 41 21 7.6 4.2
28000 -22.5 -8.5 240 37 19 6.9 3.8 | -22.4 -8.3 245 41 21 7.7 4.2
27000 -20.5 -4.9 245 37 19 6.9 3.8 | -20.1 -4.2 245 39 20 7.7 4.2
26000 -18.4 -1.1 250 36 18 6.9 3.8 | -17.8 -0.0 245 36 19 7.7 4.2
25000 -16.4 2.5 250 35 18 6.8 3.7 | -15.5 4.1 245 34 18 7.6 4.2
24000 -14.6 5.7 255 32 17 5.9 3.3 | -13.7 7.3 245 33 17 5.8 3.2
23000 -12.8 9.0 260 29 15 5.9 3.3 | -12.0 10.4 250 32 16 5.8 3.2
22000 -11.1 12.0 265 26 14 6.2 3.4 | -10.3 13.5 255 30 16 5.9 3.2
21000 -9.0 15.8 265 26 13 7.4 4.1 | -8.6 16.5 255 28 14 6.4 3.5
20000 -6.8 19.8 270 26 13 7.5 4.1 | -6.8 19.8 260 25 13 6.4 3.5
19500 -5.7 21.7 270 25 13 7.5 4.1 | -5.9 21.4 260 24 12 6.5 3.6
19000 -4.6 23.7 270 25 13 7.7 4.2 | -5.0 23.0 260 23 12 6.5 3.5
18500 -3.5 25.7 275 25 13 7.8 4.3 | -4.1 24.6 260 22 11 6.4 3.5
18000 -2.4 27.7 275 25 13 7.7 4.2 | -3.1 26.4 260 22 11 6.5 3.5
17500 -1.4 29.5 280 25 13 7.1 3.9 | -1.6 29.1 265 21 11 7.0 3.9
17000 0.2 32.4 280 25 13 7.2 4.0 | -0.6 30.9 265 20 10 7.1 3.9
16500 1.2 34.2 280 25 13 7.6 4.2 | 0.5 32.9 265 19 10 8.1 4.4
16000 2.3 36.1 285 25 13 7.6 4.2 | 1.7 35.1 270 18 9 8.0 4.4
15500 3.5 38.3 285 25 13 8.0 4.4 | 2.8 37.0 270 17 9 8.3 4.5
15000 4.6 40.3 285 25 13 8.0 4.4 | 4.1 39.4 270 16 8 8.4 4.6
14500 5.8 42.4 285 25 13 8.1 4.4 | 5.3 41.5 275 16 8 8.5 4.6
14000 6.9 44.4 290 23 12 8.1 4.4 | 6.5 43.7 275 15 8 8.6 4.7
13500 8.1 46.6 290 22 11 8.2 4.5 | 7.8 46.0 275 14 7 8.6 4.7
13000 9.3 48.7 290 21 11 8.4 4.6 | 9.0 48.2 280 14 7 8.3 4.5
12500 10.5 50.9 285 19 10 8.4 4.6 | 10.2 50.4 280 13 7 8.3 4.6
12000 11.8 53.2 285 18 9 9.3 5.1 | 11.4 52.5 280 12 6 8.4 4.6
11500 13.1 55.6 285 16 8 9.4 5.2 | 12.6 54.7 285 11 6 8.4 4.6
11000 14.4 57.9 280 15 8 7.7 4.2 | 13.8 56.8 285 11 6 7.9 4.4
10500 15.6 60.1 280 13 7 9.8 5.4 | 15.0 59.0 290 10 5 9.3 5.1
10250 16.4 61.5 275 12 6 10.8 5.9 | 15.8 60.4 290 10 5 10.9 6.0
10000 17.1 62.8 275 11 6 8.4 4.6 | 16.5 61.7 290 10 5 9.1 5.0
9750 17.7 63.9 270 11 5 8.5 4.6 | 17.2 63.0 295 9 5 8.7 4.8
9500 18.3 64.9 270 10 5 8.9 4.9 | 17.8 64.0 295 9 5 8.5 4.6
9250 19.0 66.2 265 9 5 7.2 4.0 | 18.5 65.3 295 9 5 9.9 5.4
9000 19.5 67.1 260 8 4 7.3 4.0 | 19.3 66.7 295 8 4 10.3 5.6
8750 20.1 68.2 255 8 4 8.9 4.9 | 20.0 68.0 295 8 4 8.9 4.9
8500 20.7 69.3 245 7 4 8.7 4.8 | 20.6 69.1 295 7 4 9.7 5.3
8250 21.3 70.3 235 6 3 7.7 4.2 | 21.3 70.3 295 7 4 8.0 4.4
8000 21.9 71.4 230 6 3 7.4 4.1 | 21.9 71.4 295 7 4 7.6 4.2
7750 22.5 72.5 215 6 3 8.4 4.6 | 22.5 72.5 295 7 3 8.8 4.8
7500 23.1 73.6 205 7 3 8.2 4.5 | 23.1 73.6 295 6 3 8.8 4.8
7250 23.7 74.7 200 7 4 7.0 3.9 | 23.8 74.8 290 6 3 7.4 4.1
7000 24.1 75.4 195 8 4 5.8 3.2 | 24.3 75.7 290 6 3 6.4 3.5
6750 24.5 76.1 185 8 4 5.0 2.7 | 24.8 76.6 290 6 3 7.7 4.2
6500 24.8 76.6 180 9 5 5.0 2.7 | 25.3 77.5 285 5 3 7.9 4.4
6250 25.2 77.4 175 10 5 5.9 3.2 | 25.9 78.6 285 5 3 8.5 4.7
6000 25.7 78.3 170 10 5 6.6 3.6 | 26.6 79.9 285 5 3 9.0 4.9
5750 26.1 79.0 170 10 5 4.2 2.3 | 27.2 81.0 285 5 3 9.3 5.1
5500 26.2 79.2 170 9 5 5.9 3.2 | 28.0 82.4 290 5 3 11.5 6.3
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 UTC) and again by approximately 1830 MST/1930 MDT (0130 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 old Stapleton
Airport site in Denver, Colorado at
North Latitude: 39 deg 46 min 5.016 sec
West Longitude: 104 deg 52 min 9.984 sec
Elevation: 5285 feet (1611 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.
CINH (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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