Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
070
UXUS97 KBOU 010111
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1910 MDT Monday, June 30, 2025
This forecast is for Tuesday, July 1, 2025:
If the trigger temperature of 80.9 F/27.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1048 ft/min (5.3 m/s)
Maximum height of thermals.................. 17077 ft MSL (11776 ft AGL)
Forecast maximum temperature................... 91.0 F/33.2 C
Time of trigger temperature.................... 1045 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................. 11849 ft MSL (6548 ft AGL)
Thermal soaring outlook for Wednesday 07/02.... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT).........
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 17106 ft MSL (11805 ft AGL)
Wave soaring outlook for Wednesday 07/02....... Poor
Remarks...
Sunrise/Sunset.................... 05:35:29 / 20:31:29 MDT
Total possible sunshine........... 14 hr 56 min 0 sec (896 min 0 sec)
Altitude of sun at 13:03:29 MDT... 73.26 degrees
Upper air data from numerical model forecast valid on 07/01/2025 at 0600 MDT
Freezing level.................. 15880 ft MSL (10579 ft AGL)
Convective condensation level... 17276 ft MSL (11975 ft AGL)
Lifted condensation level....... 17386 ft MSL (12085 ft AGL)
Lifted index.................... -1.4
K index......................... +17.1
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 -62.4 -80.3 340 25 13 2.7 1.5 M M M M M
45000 -57.7 -71.9 325 22 11 3.7 2.0 M M M M M
40000 -52.0 -61.6 275 17 9 4.6 2.5 M M M M M
38000 -49.2 -56.6 270 23 12 4.6 2.5 M M M M M
36000 -46.4 -51.5 265 29 15 4.2 2.3 M M M M M
34000 -41.5 -42.7 255 26 13 8.6 4.7 M M M M M
32000 -36.4 -33.5 245 22 11 8.5 4.6 M M M M M
30000 -30.9 -23.6 220 19 10 8.2 4.5 44.7 112.4 9.0 M M
29000 -28.4 -19.1 210 18 9 8.2 4.5 44.1 111.5 8.7 M M
28000 -26.1 -15.0 200 19 10 6.8 3.7 43.5 110.3 8.3 M M
27000 -24.0 -11.2 195 18 9 6.9 3.8 42.3 108.2 7.5 M M
26000 -21.9 -7.4 195 18 9 7.0 3.8 41.3 106.3 6.8 M M
25000 -19.8 -3.6 195 18 9 7.4 4.0 40.4 104.7 6.1 M M
24000 -17.4 0.7 190 16 8 7.9 4.3 39.6 103.3 5.5 M M
23000 -15.0 5.0 185 15 7 7.9 4.3 38.9 102.1 5.1 M M
22000 -12.6 9.3 180 13 7 7.0 3.8 38.4 101.0 4.7 M M
21000 -10.8 12.6 185 10 5 6.3 3.4 37.0 98.6 3.6 M M
20000 -8.9 16.0 190 6 3 6.3 3.5 35.8 96.5 2.5 M M
19500 -8.0 17.6 200 4 2 6.4 3.5 35.3 95.5 2.0 M M
19000 -7.0 19.4 210 2 1 7.0 3.8 34.8 94.6 1.6 M M
18500 -6.0 21.2 295 1 0 7.0 3.8 34.3 93.7 1.1 M M
18000 -5.0 23.0 355 2 1 7.6 4.1 33.8 92.9 0.7 M M
17500 -3.9 25.0 345 3 2 7.9 4.3 33.5 92.3 0.3 M M
17000 -2.8 27.0 335 4 2 8.0 4.4 33.2 91.7 0.0 M M
16500 -1.6 29.1 330 5 2 7.9 4.3 32.9 91.2 -0.3 1003 5.1
16000 -0.5 31.1 330 5 2 7.9 4.4 32.6 90.6 -0.7 955 4.9
15500 1.2 34.2 325 4 2 8.7 4.8 32.2 90.0 -1.1 879 4.5
15000 2.5 36.5 320 4 2 8.7 4.8 32.0 89.6 -1.3 827 4.2
14500 3.8 38.8 320 4 2 8.2 4.5 31.8 89.3 -1.5 775 3.9
14000 5.0 41.0 315 3 2 8.3 4.6 31.6 88.8 -1.8 723 3.7
13500 6.2 43.2 305 2 1 7.7 4.2 31.3 88.3 -2.0 672 3.4
13000 7.4 45.3 285 2 1 7.7 4.2 31.0 87.7 -2.3 621 3.2
12500 8.6 47.5 260 2 1 7.8 4.3 30.6 87.1 -2.6 570 2.9
12000 9.7 49.5 235 3 1 7.8 4.3 30.3 86.6 -2.9 522 2.7
11500 10.8 51.4 225 4 2 7.6 4.2 30.0 86.0 -3.3 474 2.4
11000 11.9 53.4 210 6 3 7.2 3.9 29.6 85.3 -3.7 426 2.2
10500 13.0 55.4 205 8 4 3.2 1.7 29.3 84.7 -4.1 379 1.9
10250 13.1 55.6 205 8 4 3.3 1.8 28.6 83.4 -4.7 369 1.9
10000 13.7 56.7 200 9 5 9.3 5.1 28.4 83.1 -4.9 345 1.8
9750 14.3 57.7 200 11 6 9.2 5.0 28.3 83.0 -5.0 317 1.6
9500 14.9 58.8 200 12 6 6.5 3.6 28.3 82.9 -5.1 291 1.5
9250 15.3 59.5 200 13 7 3.7 2.0 27.8 82.1 -5.5 275 1.4
9000 15.6 60.1 195 14 7 6.5 3.6 27.5 81.4 -5.9 257 1.3
8750 16.1 61.0 195 15 8 7.9 4.3 27.3 81.1 -6.1 234 1.2
8500 16.6 61.9 195 16 8 5.8 3.2 27.1 80.7 -6.4 212 1.1
8250 16.9 62.4 190 17 9 4.5 2.5 26.7 80.1 -6.8 195 1.0
8000 17.3 63.1 190 18 9 5.4 3.0 26.3 79.4 -7.2 178 0.9
7750 17.6 63.7 185 19 10 5.5 3.0 26.0 78.8 -7.6 159 0.8
7500 18.0 64.4 185 19 10 4.6 2.5 25.7 78.2 -8.0 142 0.7
7250 18.3 64.9 185 18 9 3.8 2.1 25.2 77.4 -8.5 126 0.6
7000 18.5 65.3 180 18 9 5.2 2.8 24.8 76.6 -9.0 110 0.6
6750 18.9 66.0 180 17 9 1.9 1.1 24.4 75.9 -9.4 92 0.5
6500 18.7 65.7 180 16 8 -3.0 -1.7 23.6 74.4 -10.3 89 0.5
6250 18.5 65.3 185 16 8 -0.8 -0.5 22.6 72.8 -11.2 88 0.4
6000 18.3 64.9 190 15 8 -7.3 -4.0 21.7 71.1 -12.2 87 0.4
5750 17.3 63.1 190 12 6 -14.7 -8.1 20.1 68.1 -14.0 110 0.6
5500 16.3 61.3 185 9 5 -8.0 -4.4 18.4 65.2 -15.7 132 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/01/2025 at 0900 MDT | 07/01/2025 at 1200 MDT
|
CAPE... 0.0 LI... +0.4 | CAPE... +347.2 LI... -1.7
CINH... 0.0 K Index... +17.2 | CINH... -43.1 K Index... +16.4
|
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 -62.2 -80.0 350 30 15 2.9 1.6 | -62.0 -79.6 355 23 12 2.6 1.4
45000 -57.2 -71.0 340 28 14 3.6 2.0 | -56.9 -70.4 345 26 13 4.9 2.7
40000 -51.7 -61.1 290 17 9 4.3 2.4 | -49.8 -57.6 325 16 8 3.2 1.7
38000 -49.1 -56.4 275 17 9 4.3 2.4 | -47.9 -54.2 295 12 6 3.1 1.7
36000 -46.5 -51.7 260 18 9 3.8 2.1 | -46.0 -50.8 255 12 6 2.5 1.4
34000 -41.4 -42.5 245 21 11 9.0 5.0 | -41.4 -42.5 245 18 9 8.4 4.6
32000 -36.0 -32.8 240 26 13 9.0 4.9 | -35.7 -32.3 245 24 13 8.9 4.9
30000 -30.3 -22.5 235 23 12 8.4 4.6 | -30.8 -23.4 245 23 12 8.3 4.5
29000 -27.8 -18.0 235 22 11 8.4 4.6 | -28.3 -18.9 245 21 11 8.3 4.6
28000 -25.4 -13.7 230 20 10 6.4 3.5 | -26.0 -14.8 245 20 11 6.5 3.6
27000 -23.5 -10.3 220 19 10 6.5 3.6 | -24.0 -11.2 235 20 10 6.5 3.6
26000 -21.5 -6.7 210 19 10 6.5 3.6 | -22.1 -7.8 225 20 10 6.5 3.6
25000 -19.6 -3.3 200 19 10 6.6 3.6 | -20.1 -4.2 220 21 11 6.8 3.7
24000 -17.6 0.3 195 17 9 6.6 3.6 | -18.0 -0.4 215 19 10 7.1 3.9
23000 -15.6 3.9 195 15 8 6.7 3.6 | -15.9 3.4 215 17 9 7.2 3.9
22000 -13.7 7.3 190 13 7 6.4 3.5 | -13.8 7.2 210 15 8 6.8 3.7
21000 -11.8 10.8 190 9 5 6.2 3.4 | -11.8 10.8 205 12 6 6.5 3.6
20000 -9.9 14.2 200 4 2 6.3 3.4 | -9.7 14.5 200 9 4 6.6 3.6
19500 -8.9 16.0 220 2 1 6.3 3.4 | -8.7 16.3 195 7 4 6.6 3.6
19000 -7.9 17.8 260 1 1 7.9 4.3 | -7.7 18.1 195 6 3 7.9 4.3
18500 -6.8 19.8 305 2 1 7.9 4.3 | -6.5 20.3 205 4 2 7.9 4.3
18000 -5.7 21.7 325 3 1 8.1 4.5 | -5.4 22.3 230 3 1 8.4 4.6
17500 -4.5 23.9 320 3 2 8.4 4.6 | -4.2 24.4 255 3 2 8.8 4.8
17000 -3.4 25.9 315 4 2 8.6 4.7 | -3.0 26.6 275 4 2 9.1 5.0
16500 -2.2 28.0 315 4 2 8.5 4.7 | -1.1 30.0 275 4 2 8.3 4.6
16000 -0.2 31.6 305 4 2 8.6 4.7 | 0.1 32.2 275 5 2 8.5 4.6
15500 1.1 34.0 295 3 2 8.7 4.8 | 1.5 34.7 270 4 2 9.0 4.9
15000 2.4 36.3 280 2 1 8.8 4.8 | 2.8 37.0 260 4 2 9.0 4.9
14500 3.7 38.7 260 2 1 7.9 4.3 | 4.1 39.4 255 4 2 8.2 4.5
14000 4.9 40.8 235 2 1 8.0 4.4 | 5.4 41.7 245 4 2 8.3 4.5
13500 6.1 43.0 220 3 1 8.2 4.5 | 6.6 43.9 240 5 2 8.4 4.6
13000 7.4 45.3 215 4 2 8.2 4.5 | 7.9 46.2 235 5 3 8.5 4.6
12500 8.6 47.5 210 4 2 8.0 4.4 | 9.1 48.4 230 6 3 8.3 4.6
12000 9.7 49.5 210 5 3 7.9 4.4 | 10.3 50.5 225 7 3 8.3 4.5
11500 10.8 51.4 210 6 3 7.9 4.3 | 11.6 52.9 225 7 4 8.3 4.6
11000 12.1 53.8 210 8 4 7.6 4.2 | 12.8 55.0 220 8 4 8.2 4.5
10500 13.3 55.9 210 10 5 3.5 1.9 | 14.1 57.4 220 8 4 4.4 2.4
10250 13.4 56.1 210 10 5 4.0 2.2 | 14.3 57.7 220 8 4 6.1 3.3
10000 14.0 57.2 210 11 6 10.0 5.5 | 15.0 59.0 220 8 4 11.6 6.4
9750 14.6 58.3 210 12 6 9.4 5.1 | 15.8 60.4 225 9 4 10.5 5.8
9500 15.2 59.4 210 14 7 7.0 3.9 | 16.5 61.7 225 9 4 7.7 4.2
9250 15.6 60.1 210 14 7 4.6 2.5 | 16.9 62.4 220 9 4 5.3 2.9
9000 16.0 60.8 210 15 8 6.7 3.7 | 17.3 63.1 215 9 5 7.9 4.3
8750 16.5 61.7 210 16 8 7.4 4.1 | 17.8 64.0 210 9 5 8.6 4.7
8500 16.9 62.4 210 16 8 6.5 3.6 | 18.4 65.1 205 9 5 8.5 4.7
8250 17.4 63.3 210 17 9 5.9 3.2 | 19.0 66.2 205 9 5 8.4 4.6
8000 17.8 64.0 210 17 9 6.5 3.6 | 19.5 67.1 200 9 5 9.3 5.1
7750 18.3 64.9 210 17 9 6.2 3.4 | 20.2 68.4 200 9 5 10.3 5.6
7500 18.6 65.5 205 17 9 4.2 2.3 | 21.0 69.8 200 9 5 10.1 5.6
7250 18.9 66.0 205 17 9 3.4 1.9 | 21.7 71.1 200 9 5 10.1 5.6
7000 19.1 66.4 205 16 8 3.9 2.1 | 22.5 72.5 200 9 5 10.1 5.6
6750 19.4 66.9 200 16 8 3.7 2.0 | 23.2 73.8 200 9 5 10.4 5.7
6500 19.6 67.3 200 14 7 3.5 1.9 | 24.0 75.2 200 9 4 10.7 5.9
6250 19.8 67.6 195 12 6 3.0 1.6 | 24.8 76.6 200 8 4 10.6 5.8
6000 20.0 68.0 190 10 5 5.4 2.9 | 25.6 78.1 200 8 4 10.9 6.0
5750 20.6 69.1 190 8 4 13.6 7.4 | 26.6 79.9 200 8 4 17.6 9.6
5500 21.9 71.4 190 7 4 19.9 10.9 | 28.3 82.9 200 8 4 27.8 15.2
07/01/2025 at 1500 MDT | 07/01/2025 at 1800 MDT
|
CAPE... +309.4 LI... -1.4 | CAPE... +251.4 LI... -1.4
CINH... -22.5 K Index... +21.0 | CINH... -29.1 K Index... +26.6
|
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 -62.3 -80.1 345 17 9 3.1 1.7 | -62.7 -80.9 340 17 9 3.3 1.8
45000 -56.4 -69.5 335 23 12 5.4 3.0 | -56.4 -69.5 330 20 10 5.9 3.2
40000 -48.7 -55.7 325 17 9 3.1 1.7 | -47.8 -54.0 305 16 8 3.2 1.7
38000 -46.9 -52.4 280 16 8 3.0 1.7 | -45.9 -50.6 275 19 10 3.2 1.8
36000 -45.1 -49.2 250 22 11 2.5 1.4 | -44.0 -47.2 260 25 13 3.7 2.0
34000 -40.2 -40.4 250 25 13 7.9 4.3 | -39.8 -39.6 255 21 11 7.3 4.0
32000 -35.4 -31.7 250 28 14 8.4 4.6 | -35.4 -31.7 255 16 8 7.1 3.9
30000 -30.8 -23.4 255 22 11 7.8 4.3 | -30.8 -23.4 255 13 7 7.9 4.3
29000 -28.5 -19.3 255 19 10 7.8 4.3 | -28.4 -19.1 255 12 6 7.9 4.3
28000 -26.1 -15.0 255 17 9 7.4 4.1 | -25.5 -13.9 260 10 5 7.2 4.0
27000 -23.9 -11.0 255 18 9 7.5 4.1 | -23.4 -10.1 270 9 5 7.3 4.0
26000 -21.7 -7.1 255 18 9 7.5 4.1 | -21.2 -6.2 280 8 4 7.3 4.0
25000 -19.5 -3.1 250 19 10 7.2 3.9 | -19.1 -2.4 290 8 4 7.1 3.9
24000 -17.5 0.5 245 18 9 6.5 3.6 | -17.1 1.2 275 8 4 6.9 3.8
23000 -15.6 3.9 235 17 9 6.5 3.6 | -15.0 5.0 265 8 4 6.9 3.8
22000 -13.7 7.3 225 16 8 6.8 3.7 | -13.0 8.6 255 9 5 7.1 3.9
21000 -11.5 11.3 225 13 7 7.1 3.9 | -10.9 12.4 255 7 4 7.3 4.0
20000 -9.3 15.3 220 11 5 7.1 3.9 | -8.8 16.2 255 5 3 7.3 4.0
19500 -8.2 17.2 215 9 5 7.1 3.9 | -7.7 18.1 255 5 2 7.1 3.9
19000 -7.1 19.2 210 8 4 7.1 3.9 | -6.7 19.9 255 3 1 5.4 3.0
18500 -6.0 21.2 205 6 3 7.2 3.9 | -5.8 21.6 240 1 0 5.6 3.1
18000 -4.9 23.2 195 4 2 7.8 4.3 | -4.9 23.2 090 1 1 7.0 3.9
17500 -3.7 25.3 210 3 1 8.4 4.6 | -3.8 25.2 075 2 1 7.7 4.2
17000 -2.0 28.4 265 2 1 8.9 4.9 | -2.7 27.1 070 3 2 7.8 4.3
16500 -0.7 30.7 285 2 1 9.0 4.9 | -1.5 29.3 075 3 2 8.5 4.7
16000 0.6 33.1 300 2 1 8.9 4.9 | -0.3 31.5 090 3 2 8.6 4.7
15500 1.9 35.4 305 2 1 8.5 4.7 | 0.9 33.6 100 3 2 8.1 4.4
15000 3.2 37.8 310 1 1 8.5 4.7 | 2.0 35.6 125 4 2 8.2 4.5
14500 4.5 40.1 300 1 0 8.7 4.8 | 3.1 37.6 140 5 2 8.5 4.7
14000 5.8 42.4 240 1 0 8.7 4.8 | 5.0 41.0 145 5 3 8.8 4.8
13500 7.1 44.8 185 1 1 8.3 4.5 | 6.2 43.2 150 6 3 9.2 5.1
13000 8.3 46.9 175 2 1 8.2 4.5 | 7.6 45.7 150 6 3 9.3 5.1
12500 9.5 49.1 170 3 2 8.6 4.7 | 9.0 48.2 155 6 3 9.2 5.0
12000 10.7 51.3 175 5 2 9.0 4.9 | 10.3 50.5 160 5 3 9.2 5.0
11500 11.9 53.4 175 6 3 9.1 5.0 | 11.6 52.9 160 5 3 9.4 5.1
11000 13.2 55.8 175 6 3 8.9 4.9 | 13.1 55.6 165 5 2 9.2 5.1
10500 14.6 58.3 175 6 3 4.8 2.6 | 14.5 58.1 175 4 2 5.0 2.7
10250 14.8 58.6 175 6 3 6.6 3.6 | 14.7 58.5 180 4 2 6.4 3.5
10000 15.7 60.3 175 6 3 13.3 7.3 | 15.6 60.1 185 3 2 13.1 7.2
9750 16.5 61.7 180 6 3 12.1 6.6 | 16.5 61.7 195 3 2 12.0 6.6
9500 17.4 63.3 180 6 3 10.2 5.6 | 17.3 63.1 205 3 2 9.6 5.3
9250 18.0 64.4 180 6 3 8.3 4.6 | 17.9 64.2 220 3 2 7.6 4.1
9000 18.7 65.7 180 6 3 10.2 5.6 | 18.6 65.5 230 3 2 9.8 5.4
8750 19.5 67.1 180 6 3 10.4 5.7 | 19.3 66.7 240 4 2 10.1 5.5
8500 20.3 68.5 180 6 3 10.5 5.8 | 20.1 68.2 250 4 2 9.6 5.3
8250 21.1 70.0 180 6 3 10.7 5.9 | 20.8 69.4 260 5 2 9.3 5.1
8000 21.8 71.2 180 6 3 10.3 5.6 | 21.5 70.7 265 5 3 9.5 5.2
7750 22.6 72.7 180 6 3 9.8 5.4 | 22.2 72.0 265 6 3 9.6 5.3
7500 23.3 73.9 180 6 3 9.8 5.4 | 22.9 73.2 265 6 3 9.4 5.2
7250 24.1 75.4 185 6 3 9.8 5.4 | 23.6 74.5 270 7 3 9.5 5.2
7000 24.8 76.6 185 6 3 9.7 5.3 | 24.3 75.7 270 7 4 9.2 5.0
6750 25.5 77.9 185 6 3 10.1 5.6 | 25.0 77.0 270 7 4 9.4 5.1
6500 26.3 79.3 185 5 3 10.8 5.9 | 25.7 78.3 270 7 4 10.1 5.6
6250 27.2 81.0 185 5 3 11.4 6.2 | 26.5 79.7 270 8 4 11.1 6.1
6000 28.0 82.4 185 5 3 9.5 5.2 | 27.3 81.1 270 8 4 8.5 4.6
5750 28.8 83.8 185 5 3 15.9 8.7 | 27.8 82.0 270 8 4 10.9 6.0
5500 30.6 87.1 185 5 3 31.8 17.4 | 29.0 84.2 270 7 4 22.2 12.2
________________________________________________________________________________
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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