Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
092
UXUS97 KBOU 301334
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0729 MDT Sunday, June 30, 2024
This forecast is for Sunday, June 30, 2024:
If the trigger temperature of 81.6 F/27.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1296 ft/min (6.6 m/s)
Maximum height of thermals.................. 17811 ft MSL (12482 ft AGL)
Forecast maximum temperature................... 94.0 F/34.9 C
Time of trigger temperature.................... 1100 MDT
Time of overdevelopment........................ 1800 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12751 ft MSL (7422 ft AGL)
Thermal soaring outlook for Monday 07/01....... 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)................ Weak PVA
Potential height of wave....................... 14436 ft MSL (9107 ft AGL)
Wave soaring outlook for Monday 07/01.......... Poor
Remarks...
Sunrise/Sunset.................... 05:35:06 / 20:31:34 MDT
Total possible sunshine........... 14 hr 56 min 28 sec (896 min 28 sec)
Altitude of sun at 13:03:20 MDT... 73.32 degrees
Upper air data from numerical model forecast valid on 06/30/2024 at 0600 MDT
Freezing level.................. 16461 ft MSL (11132 ft AGL)
Convective condensation level... 13800 ft MSL (8471 ft AGL)
Lifted condensation level....... 14909 ft MSL (9581 ft AGL)
Lifted index.................... -5.2
K index......................... +27.2
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 -64.8 -84.6 270 37 19 2.9 1.6 M M M M M
45000 -58.5 -73.3 260 52 27 6.0 3.3 M M M M M
40000 -48.8 -55.8 240 66 34 8.0 4.4 M M M M M
38000 -44.0 -47.2 240 64 33 8.0 4.4 M M M M M
36000 -39.2 -38.6 240 62 32 7.4 4.0 M M M M M
34000 -34.5 -30.1 245 57 29 7.0 3.8 M M M M M
32000 -30.3 -22.5 245 53 27 8.1 4.5 52.7 126.8 13.5 M M
30000 -26.0 -14.8 250 45 23 7.2 4.0 50.4 122.8 12.1 M M
29000 -23.9 -11.0 250 41 21 7.2 4.0 49.5 121.2 11.5 M M
28000 -21.8 -7.2 250 37 19 6.6 3.6 48.5 119.3 10.8 M M
27000 -19.8 -3.6 250 35 18 6.6 3.6 47.2 117.0 9.9 M M
26000 -17.9 -0.2 245 32 16 6.6 3.6 46.1 114.9 9.0 M M
25000 -16.0 3.2 245 30 15 6.2 3.4 45.0 113.0 8.2 M M
24000 -14.2 6.4 240 27 14 5.9 3.3 43.5 110.3 7.0 M M
23000 -12.5 9.5 235 25 13 6.0 3.3 42.1 107.8 5.9 M M
22000 -10.8 12.6 235 23 12 5.8 3.2 40.8 105.5 4.9 M M
21000 -9.1 15.6 235 18 10 5.8 3.2 39.3 102.8 3.6 M M
20000 -7.4 18.7 235 14 7 5.8 3.2 38.0 100.3 2.4 M M
19500 -6.6 20.1 240 12 6 5.9 3.2 37.3 99.2 1.8 M M
19000 -5.7 21.7 240 10 5 6.3 3.5 36.7 98.1 1.3 M M
18500 -4.8 23.4 240 7 4 6.3 3.4 36.1 97.0 0.7 M M
18000 -3.3 26.1 240 5 3 7.7 4.2 35.3 95.6 0.1 M M
17500 -2.2 28.0 240 4 2 7.6 4.2 35.0 94.9 -0.3 1055 5.4
17000 -1.1 30.0 245 4 2 8.1 4.4 34.6 94.3 -0.6 1007 5.1
16500 0.1 32.2 245 4 2 8.2 4.5 34.4 93.9 -0.9 956 4.9
16000 1.3 34.3 250 4 2 8.3 4.5 34.1 93.4 -1.2 905 4.6
15500 2.5 36.5 250 4 2 8.2 4.5 33.9 93.0 -1.4 854 4.3
15000 3.8 38.8 255 5 2 8.2 4.5 33.6 92.5 -1.7 803 4.1
14500 5.0 41.0 255 5 3 8.2 4.5 33.4 92.0 -1.9 753 3.8
14000 6.1 43.0 260 6 3 8.2 4.5 33.1 91.6 -2.2 702 3.6
13500 7.3 45.1 260 7 3 7.8 4.3 32.8 91.1 -2.5 652 3.3
13000 8.5 47.3 255 8 4 7.8 4.3 32.5 90.5 -2.9 603 3.1
12500 9.6 49.3 255 9 5 7.7 4.2 32.2 89.9 -3.2 555 2.8
12000 10.7 51.3 255 10 5 7.7 4.2 31.9 89.3 -3.6 506 2.6
11500 11.8 53.2 250 12 6 7.2 4.0 31.5 88.8 -3.9 458 2.3
11000 12.8 55.0 245 13 7 6.6 3.6 31.1 87.9 -4.4 414 2.1
10500 13.8 56.8 240 15 8 3.3 1.8 30.6 87.1 -4.9 370 1.9
10250 13.9 57.0 240 15 8 3.5 1.9 29.9 85.9 -5.5 359 1.8
10000 14.4 57.9 240 16 8 8.4 4.6 29.7 85.5 -5.8 337 1.7
9750 14.9 58.8 235 17 9 8.5 4.6 29.6 85.3 -6.0 313 1.6
9500 15.5 59.9 235 18 9 5.5 3.0 29.5 85.1 -6.2 290 1.5
9250 15.6 60.1 235 18 9 2.2 1.2 28.9 84.1 -6.7 277 1.4
9000 15.9 60.6 235 18 9 4.3 2.4 28.4 83.2 -7.3 263 1.3
8750 16.2 61.2 230 18 9 5.3 2.9 28.1 82.5 -7.7 247 1.3
8500 16.4 61.5 225 19 10 4.0 2.2 27.7 81.8 -8.2 231 1.2
8250 16.6 61.9 225 19 10 3.1 1.7 27.2 80.9 -8.7 217 1.1
8000 16.8 62.2 220 19 10 3.4 1.9 26.7 80.0 -9.3 204 1.0
7750 17.0 62.6 215 19 10 3.4 1.9 26.2 79.2 -9.9 191 1.0
7500 17.2 63.0 205 20 10 3.4 1.9 25.7 78.3 -10.4 178 0.9
7250 17.4 63.3 205 20 10 3.4 1.9 25.2 77.4 -10.9 164 0.8
7000 17.7 63.9 200 20 10 3.1 1.7 24.7 76.5 -11.5 150 0.8
6750 17.8 64.0 195 20 10 2.1 1.1 24.2 75.6 -12.1 138 0.7
6500 17.9 64.2 190 19 10 2.1 1.2 23.6 74.5 -12.7 127 0.6
6250 18.1 64.6 185 17 9 1.8 1.0 23.0 73.5 -13.4 116 0.6
6000 18.2 64.8 180 16 8 4.2 2.3 22.5 72.4 -14.0 104 0.5
5750 18.6 65.5 180 15 8 4.5 2.5 22.1 71.9 -14.4 86 0.4
5500 18.6 65.5 180 11 6 -2.4 -1.3 21.5 70.7 -15.0 76 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/30/2024 at 0900 MDT | 06/30/2024 at 1200 MDT
|
CAPE... +376.1 LI... -3.0 | CAPE... +345.2 LI... -2.4
CINH... -125.8 K Index... +26.2 | CINH... -36.3 K Index... +26.5
|
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 -64.3 -83.7 260 30 16 2.8 1.5 | -64.2 -83.6 245 26 13 3.3 1.8
45000 -58.2 -72.8 255 45 23 5.8 3.2 | -57.7 -71.9 250 39 20 5.6 3.1
40000 -48.8 -55.8 245 58 30 8.2 4.5 | -48.5 -55.3 250 54 28 7.8 4.3
38000 -43.9 -47.0 240 58 30 8.2 4.5 | -43.8 -46.8 245 54 28 7.9 4.3
36000 -38.4 -37.1 240 58 30 7.2 4.0 | -39.1 -38.4 240 55 28 7.7 4.2
34000 -34.0 -29.2 240 56 29 7.3 4.0 | -34.0 -29.2 240 54 28 7.6 4.2
32000 -29.7 -21.5 245 54 28 7.6 4.1 | -29.4 -20.9 240 52 27 7.5 4.1
30000 -25.7 -14.3 245 45 23 6.6 3.6 | -25.6 -14.1 240 46 24 6.6 3.6
29000 -23.8 -10.8 245 41 21 6.7 3.7 | -23.6 -10.5 245 44 22 6.6 3.6
28000 -21.8 -7.2 245 37 19 7.0 3.8 | -21.6 -6.9 245 41 21 6.9 3.8
27000 -19.7 -3.5 245 35 18 7.0 3.8 | -19.6 -3.3 245 39 20 6.9 3.8
26000 -17.6 0.3 245 33 17 7.0 3.8 | -17.6 0.3 240 36 19 6.9 3.8
25000 -15.6 3.9 240 31 16 6.1 3.4 | -15.5 4.1 240 34 17 6.6 3.6
24000 -13.9 7.0 245 29 15 5.7 3.1 | -13.6 7.5 245 33 17 6.5 3.6
23000 -12.3 9.9 245 27 14 5.7 3.1 | -11.6 11.1 245 32 17 6.5 3.6
22000 -10.6 12.9 245 26 13 5.7 3.1 | -9.7 14.5 245 31 16 5.7 3.1
21000 -9.0 15.8 245 21 11 5.7 3.1 | -8.2 17.2 245 27 14 5.5 3.0
20000 -7.4 18.7 240 17 9 5.7 3.1 | -6.7 19.9 245 24 12 5.7 3.1
19500 -6.6 20.1 240 14 7 5.9 3.2 | -5.9 21.4 250 22 11 5.7 3.1
19000 -5.1 22.8 235 11 6 7.0 3.8 | -5.2 22.6 245 20 10 5.2 2.8
18500 -4.1 24.6 230 9 5 7.0 3.9 | -4.4 24.1 245 18 9 5.2 2.8
18000 -3.1 26.4 230 8 4 7.1 3.9 | -3.1 26.4 240 14 7 7.1 3.9
17500 -2.0 28.4 230 6 3 7.1 3.9 | -2.1 28.2 240 12 6 7.0 3.8
17000 -1.0 30.2 230 5 2 7.5 4.1 | -1.1 30.0 245 10 5 7.5 4.1
16500 0.2 32.4 235 4 2 7.7 4.2 | 0.1 32.2 250 9 5 7.6 4.2
16000 1.3 34.3 245 3 1 7.8 4.3 | 1.2 34.2 260 8 4 7.8 4.3
15500 2.5 36.5 265 2 1 8.1 4.5 | 2.4 36.3 270 7 4 8.3 4.5
15000 3.7 38.7 290 2 1 8.1 4.5 | 3.6 38.5 280 7 4 8.2 4.5
14500 4.8 40.6 310 3 2 8.1 4.4 | 4.9 40.8 285 7 3 8.6 4.7
14000 6.0 42.8 320 4 2 8.1 4.4 | 6.1 43.0 295 7 3 8.5 4.7
13500 7.3 45.1 320 4 2 8.3 4.6 | 7.4 45.3 300 7 3 8.7 4.8
13000 8.5 47.3 320 5 3 8.4 4.6 | 8.7 47.7 305 7 4 8.7 4.8
12500 9.7 49.5 315 6 3 8.1 4.4 | 10.0 50.0 310 7 4 8.9 4.9
12000 10.9 51.6 305 6 3 7.9 4.3 | 11.3 52.3 310 7 4 9.0 4.9
11500 12.0 53.6 295 7 3 7.5 4.1 | 12.6 54.7 310 8 4 8.6 4.7
11000 13.1 55.6 285 7 4 6.9 3.8 | 13.9 57.0 310 8 4 8.1 4.5
10500 14.1 57.4 275 8 4 3.4 1.9 | 15.0 59.0 310 8 4 3.4 1.9
10250 14.2 57.6 280 8 4 3.6 2.0 | 15.2 59.4 310 8 4 5.1 2.8
10000 14.7 58.5 270 9 5 8.5 4.7 | 15.9 60.6 310 8 4 11.5 6.3
9750 15.3 59.5 265 10 5 7.9 4.3 | 16.6 61.9 305 8 4 10.5 5.7
9500 15.8 60.4 255 11 6 5.9 3.2 | 17.3 63.1 305 7 4 6.9 3.8
9250 16.1 61.0 255 11 6 3.6 2.0 | 17.6 63.7 305 7 4 4.4 2.4
9000 16.4 61.5 255 12 6 5.4 3.0 | 18.1 64.6 300 6 3 8.5 4.7
8750 16.8 62.2 250 12 6 6.2 3.4 | 18.7 65.7 300 5 3 9.5 5.2
8500 17.2 63.0 245 13 7 4.9 2.7 | 19.3 66.7 295 4 2 7.1 3.9
8250 17.4 63.3 240 13 7 3.9 2.2 | 19.7 67.5 295 4 2 4.7 2.6
8000 17.7 63.9 240 13 6 4.4 2.4 | 20.1 68.2 300 3 2 7.7 4.2
7750 18.0 64.4 235 13 7 4.3 2.3 | 20.7 69.3 300 3 1 9.7 5.3
7500 18.2 64.8 230 13 6 3.4 1.8 | 21.4 70.5 305 2 1 7.9 4.3
7250 18.3 64.9 230 12 6 2.5 1.4 | 21.9 71.4 305 2 1 6.3 3.5
7000 18.5 65.3 225 11 6 3.9 2.1 | 22.4 72.3 310 2 1 9.8 5.4
6750 18.8 65.8 215 11 5 7.2 3.9 | 23.3 73.9 315 2 1 13.4 7.4
6500 19.4 66.9 215 10 5 7.7 4.2 | 24.2 75.6 315 2 1 11.0 6.0
6250 19.8 67.6 210 9 5 7.1 3.9 | 25.0 77.0 315 2 1 10.7 5.9
6000 20.3 68.5 205 8 4 6.6 3.6 | 25.8 78.4 320 2 1 8.6 4.7
5750 20.9 69.6 205 7 4 11.6 6.4 | 26.5 79.7 330 2 1 14.5 8.0
5500 22.1 71.8 210 6 3 22.3 12.2 | 28.2 82.8 330 2 1 31.4 17.3
06/30/2024 at 1500 MDT | 06/30/2024 at 1800 MDT
|
CAPE... +291.1 LI... -1.2 | CAPE... +207.6 LI... -1.7
CINH... -7.3 K Index... +30.9 | CINH... -40.7 K Index... +31.1
|
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 -64.7 -84.5 235 29 15 2.8 1.5 | -64.8 -84.6 235 35 18 2.7 1.5
45000 -58.4 -73.1 240 43 22 6.2 3.4 | -58.5 -73.3 240 46 24 6.3 3.4
40000 -48.5 -55.3 245 56 29 7.8 4.3 | -48.6 -55.5 240 55 28 8.0 4.4
38000 -43.8 -46.8 240 55 28 7.8 4.3 | -43.8 -46.8 235 54 28 8.0 4.4
36000 -38.5 -37.3 235 55 28 7.6 4.2 | -38.5 -37.3 235 54 28 7.1 3.9
34000 -33.9 -29.0 235 53 27 7.6 4.2 | -34.2 -29.6 235 50 26 7.2 3.9
32000 -29.4 -20.9 235 50 26 7.7 4.2 | -29.8 -21.6 235 46 24 8.3 4.6
30000 -25.5 -13.9 240 46 24 6.6 3.6 | -25.5 -13.9 235 43 22 7.4 4.0
29000 -23.5 -10.3 240 44 22 6.6 3.6 | -23.3 -9.9 235 41 21 7.4 4.0
28000 -21.6 -6.9 240 42 21 6.6 3.6 | -21.2 -6.2 235 39 20 6.8 3.7
27000 -19.6 -3.3 245 40 21 6.6 3.6 | -19.2 -2.6 240 38 19 6.8 3.7
26000 -17.6 0.3 245 39 20 6.7 3.7 | -17.2 1.0 240 36 19 6.8 3.7
25000 -15.7 3.7 245 37 19 6.6 3.6 | -15.2 4.6 240 35 18 6.5 3.6
24000 -13.8 7.2 245 36 18 6.6 3.6 | -13.4 7.9 245 33 17 6.4 3.5
23000 -11.8 10.8 245 34 18 6.6 3.6 | -11.5 11.3 245 31 16 6.4 3.5
22000 -9.9 14.2 250 33 17 6.7 3.7 | -9.6 14.7 250 29 15 6.2 3.4
21000 -7.9 17.8 250 30 15 6.7 3.7 | -7.9 17.8 250 27 14 6.1 3.4
20000 -6.0 21.2 250 27 14 6.8 3.7 | -6.1 21.0 250 26 13 6.1 3.4
19500 -5.0 23.0 250 26 13 6.6 3.6 | -5.2 22.6 250 25 13 6.2 3.4
19000 -3.8 25.2 250 23 12 5.5 3.0 | -3.9 25.0 250 24 12 6.2 3.4
18500 -3.1 26.4 255 21 11 5.5 3.0 | -3.0 26.6 250 23 12 6.3 3.4
18000 -2.3 27.9 255 19 10 5.7 3.1 | -2.0 28.4 250 22 11 6.9 3.8
17500 -1.5 29.3 255 17 9 5.7 3.1 | -1.0 30.2 250 21 11 6.8 3.7
17000 -0.6 30.9 255 15 8 5.8 3.2 | -0.1 31.8 250 20 11 6.7 3.7
16500 0.2 32.4 255 14 7 5.9 3.2 | 0.9 33.6 250 19 10 6.7 3.7
16000 1.0 33.8 260 12 6 6.2 3.4 | 1.9 35.4 250 18 9 6.9 3.8
15500 2.0 35.6 260 11 6 7.3 4.0 | 3.0 37.4 250 17 9 7.9 4.3
15000 3.1 37.6 265 10 5 7.1 3.9 | 4.1 39.4 250 15 8 7.8 4.3
14500 4.3 39.7 265 9 5 8.8 4.8 | 5.3 41.5 250 14 7 8.1 4.4
14000 5.6 42.1 265 8 4 8.6 4.7 | 6.4 43.5 250 13 7 8.0 4.4
13500 6.9 44.4 270 8 4 9.2 5.0 | 7.6 45.7 250 12 6 8.0 4.4
13000 8.2 46.8 270 7 4 9.2 5.1 | 8.8 47.8 250 11 6 8.0 4.4
12500 9.6 49.3 270 7 3 9.3 5.1 | 10.0 50.0 245 10 5 8.2 4.5
12000 11.0 51.8 275 6 3 9.3 5.1 | 11.2 52.2 245 9 5 8.4 4.6
11500 12.4 54.3 275 6 3 9.1 5.0 | 12.4 54.3 240 9 4 8.4 4.6
11000 13.7 56.7 275 6 3 8.7 4.8 | 13.7 56.7 240 8 4 8.2 4.5
10500 15.0 59.0 275 5 3 4.1 2.2 | 14.9 58.8 235 8 4 3.6 2.0
10250 15.2 59.4 275 6 3 5.9 3.2 | 15.0 59.0 230 8 4 5.1 2.8
10000 16.1 61.0 275 5 3 13.2 7.3 | 15.8 60.4 230 8 4 12.4 6.8
9750 16.9 62.4 275 5 3 12.2 6.7 | 16.6 61.9 230 8 4 11.3 6.2
9500 17.8 64.0 275 5 2 9.0 5.0 | 17.4 63.3 230 8 4 8.5 4.6
9250 18.3 64.9 270 5 3 6.8 3.8 | 17.9 64.2 230 8 4 6.3 3.5
9000 18.9 66.0 265 5 3 10.5 5.8 | 18.5 65.3 225 9 4 9.8 5.4
8750 19.7 67.5 265 4 2 11.2 6.1 | 19.2 66.6 225 9 4 10.9 6.0
8500 20.5 68.9 260 4 2 9.3 5.1 | 20.0 68.0 225 9 5 9.2 5.0
8250 21.1 70.0 255 4 2 7.1 3.9 | 20.6 69.1 225 9 5 7.1 3.9
8000 21.6 70.9 255 5 2 9.9 5.4 | 21.2 70.2 225 9 5 9.3 5.1
7750 22.5 72.5 250 4 2 11.7 6.4 | 21.9 71.4 225 9 5 10.9 6.0
7500 23.2 73.8 245 4 2 9.4 5.2 | 22.7 72.9 225 9 5 8.9 4.9
7250 23.9 75.0 245 4 2 8.1 4.4 | 23.3 73.9 225 10 5 7.4 4.1
7000 24.5 76.1 245 5 2 9.8 5.4 | 23.9 75.0 225 10 5 9.2 5.0
6750 25.3 77.5 240 4 2 11.8 6.5 | 24.6 76.3 225 10 5 11.5 6.3
6500 26.2 79.2 240 4 2 10.6 5.8 | 25.5 77.9 225 10 5 10.3 5.6
6250 26.9 80.4 240 4 2 10.2 5.6 | 26.2 79.2 225 10 5 9.2 5.1
6000 27.7 81.9 240 5 2 9.3 5.1 | 26.9 80.4 225 10 5 9.3 5.1
5750 28.4 83.1 230 4 2 13.9 7.7 | 27.6 81.7 225 10 5 11.9 6.5
5500 29.9 85.8 235 4 2 25.1 13.8 | 28.7 83.7 225 9 5 17.0 9.4
________________________________________________________________________________
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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