Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
090
UXUS97 KBOU 150131
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1930 MDT Monday, July 14, 2025
This forecast is for Tuesday, July 15, 2025:
If the trigger temperature of 88.9 F/31.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1383 ft/min (7.0 m/s)
Maximum height of thermals.................. 19323 ft MSL (14039 ft AGL)
Forecast maximum temperature................... 95.0 F/35.5 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1600 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10353 ft MSL (5068 ft AGL)
Thermal soaring outlook for Wednesday 07/16.... Fair
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 NVA
Potential height of wave....................... 18544 ft MSL (13260 ft AGL)
Wave soaring outlook for Wednesday 07/16....... Poor
Remarks... Scattered afternoon thunderstorms
Sunrise/Sunset.................... 05:44:31 / 20:26:34 MDT
Total possible sunshine........... 14 hr 42 min 4 sec (882 min 4 sec)
Altitude of sun at 13:05:33 MDT... 71.58 degrees
Upper air data from numerical model forecast valid on 07/15/2025 at 0600 MDT
Freezing level.................. 16462 ft MSL (11178 ft AGL)
Convective condensation level... 19332 ft MSL (14048 ft AGL)
Lifted condensation level....... 19464 ft MSL (14179 ft AGL)
Lifted index.................... -1.9
K index......................... +12.6
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 -63.3 -81.9 300 23 12 1.9 1.1 M M M M M
45000 -59.5 -75.1 290 31 16 4.1 2.2 M M M M M
40000 -52.6 -62.7 270 35 18 6.4 3.5 M M M M M
38000 -48.7 -55.7 265 36 18 6.4 3.5 M M M M M
36000 -44.9 -48.8 255 37 19 6.4 3.5 M M M M M
34000 -40.4 -40.7 260 33 17 7.7 4.2 M M M M M
32000 -35.7 -32.3 260 28 15 7.7 4.2 M M M M M
30000 -31.3 -24.3 270 24 12 7.4 4.1 44.5 112.1 7.2 M M
29000 -29.0 -20.2 280 23 12 7.4 4.1 43.6 110.6 6.7 M M
28000 -26.8 -16.2 285 22 11 7.1 3.9 42.9 109.2 6.2 M M
27000 -24.4 -11.9 285 19 10 6.5 3.6 41.2 106.2 4.9 M M
26000 -22.4 -8.3 280 18 9 6.5 3.6 40.0 104.1 4.0 M M
25000 -20.5 -4.9 275 16 8 7.0 3.9 39.0 102.1 3.2 M M
24000 -18.1 -0.6 280 16 8 7.9 4.3 38.1 100.7 2.6 M M
23000 -15.8 3.6 285 15 8 7.9 4.3 37.5 99.4 2.0 M M
22000 -13.4 7.9 285 15 8 7.9 4.3 36.9 98.4 1.5 M M
21000 -11.1 12.0 295 16 8 7.9 4.3 36.1 97.1 0.9 M M
20000 -8.8 16.2 300 17 9 7.9 4.3 35.5 95.9 0.4 M M
19500 -7.6 18.3 300 18 9 7.9 4.4 35.2 95.4 0.1 M M
19000 -6.4 20.5 305 18 9 8.2 4.5 35.0 94.9 -0.2 1353 6.9
18500 -5.2 22.6 305 19 10 8.2 4.5 34.7 94.4 -0.4 1302 6.6
18000 -4.0 24.8 305 20 10 8.2 4.5 34.4 94.0 -0.7 1252 6.4
17500 -2.8 27.0 305 20 10 8.3 4.6 34.2 93.5 -0.9 1201 6.1
17000 -1.6 29.1 310 19 10 8.3 4.6 33.9 93.1 -1.2 1149 5.8
16500 -0.3 31.5 310 19 10 8.9 4.9 33.7 92.7 -1.4 1097 5.6
16000 1.0 33.8 310 19 10 8.9 4.9 33.6 92.4 -1.6 1043 5.3
15500 2.3 36.1 315 18 9 9.0 4.9 33.4 92.2 -1.7 990 5.0
15000 3.6 38.5 315 18 9 9.0 5.0 33.3 92.0 -1.9 936 4.8
14500 4.9 40.8 315 17 9 9.2 5.0 33.2 91.8 -2.1 882 4.5
14000 6.9 44.4 315 17 9 9.4 5.1 33.1 91.6 -2.2 798 4.1
13500 8.3 46.9 315 16 8 9.5 5.2 33.0 91.5 -2.3 742 3.8
13000 9.7 49.5 315 16 8 9.5 5.2 33.0 91.4 -2.4 686 3.5
12500 11.1 52.0 315 16 8 9.5 5.2 33.0 91.4 -2.5 629 3.2
12000 12.5 54.5 315 16 8 9.4 5.2 32.9 91.2 -2.5 573 2.9
11500 13.9 57.0 315 16 8 9.4 5.1 32.9 91.2 -2.6 516 2.6
11000 15.3 59.5 315 16 8 9.0 4.9 32.8 91.0 -2.7 460 2.3
10500 16.7 62.1 315 16 8 4.4 2.4 32.7 90.9 -2.8 404 2.1
10250 16.8 62.2 315 16 8 5.6 3.1 32.1 89.8 -3.4 392 2.0
10000 17.6 63.7 310 15 8 12.6 6.9 32.2 90.0 -3.3 360 1.8
9750 18.5 65.3 310 15 8 11.3 6.2 32.3 90.2 -3.2 328 1.7
9500 19.3 66.7 310 15 8 9.5 5.2 32.5 90.4 -3.1 296 1.5
9250 19.8 67.6 310 16 8 6.9 3.8 32.3 90.1 -3.3 272 1.4
9000 20.4 68.7 305 16 8 9.0 4.9 32.1 89.9 -3.4 247 1.3
8750 21.1 70.0 305 16 8 10.5 5.7 32.2 89.9 -3.5 218 1.1
8500 21.9 71.4 305 16 8 8.6 4.7 32.2 89.9 -3.5 188 1.0
8250 22.4 72.3 305 16 8 5.6 3.1 32.0 89.5 -3.7 166 0.8
8000 22.8 73.0 300 16 8 6.6 3.6 31.6 89.0 -4.0 146 0.7
7750 23.4 74.1 295 16 8 9.1 5.0 31.5 88.7 -4.2 121 0.6
7500 24.0 75.2 295 15 8 5.9 3.2 31.4 88.5 -4.3 96 0.5
7250 24.2 75.6 290 15 8 2.8 1.6 30.9 87.7 -4.8 81 0.4
7000 24.4 75.9 290 15 7 2.8 1.5 30.4 86.8 -5.3 67 0.3
6750 24.5 76.1 285 14 7 0.7 0.4 29.8 85.7 -6.0 57 0.3
6500 24.3 75.7 275 13 7 -5.4 -2.9 28.9 84.1 -6.9 55 0.3
6250 23.7 74.7 270 12 6 -9.2 -5.0 27.6 81.6 -8.3 68 0.3
6000 23.0 73.4 260 10 5 -7.3 -4.0 26.2 79.2 -9.7 81 0.4
5750 22.2 72.0 250 10 5 -15.0 -8.3 24.8 76.6 -11.3 97 0.5
5500 20.4 68.7 235 8 4 -29.2 -16.0 22.3 72.2 -13.9 144 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/15/2025 at 0900 MDT | 07/15/2025 at 1200 MDT
|
CAPE... +23.9 LI... +0.9 | CAPE... +121.2 LI... +0.1
CINH... -85.7 K Index... +13.6 | CINH... -14.3 K Index... +18.6
|
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 -62.2 -80.0 300 18 9 1.1 0.6 | -62.4 -80.3 295 15 8 0.9 0.5
45000 -59.2 -74.6 290 25 13 4.3 2.4 | -59.2 -74.6 285 20 10 5.1 2.8
40000 -52.4 -62.3 275 33 17 6.2 3.4 | -50.9 -59.6 270 29 15 6.4 3.5
38000 -48.7 -55.7 270 35 18 6.2 3.4 | -47.0 -52.6 270 32 16 6.4 3.5
36000 -44.5 -48.1 260 37 19 6.2 3.4 | -43.2 -45.8 270 35 18 6.6 3.6
34000 -40.4 -40.7 260 35 18 6.8 3.7 | -40.2 -40.4 270 37 19 4.6 2.5
32000 -36.3 -33.3 255 33 17 6.7 3.7 | -37.4 -35.3 270 38 20 4.6 2.5
30000 -32.0 -25.6 265 27 14 7.4 4.1 | -33.2 -27.8 275 37 19 7.8 4.3
29000 -29.7 -21.5 275 25 13 7.4 4.1 | -30.4 -22.7 275 35 18 7.8 4.3
28000 -27.5 -17.5 285 24 12 7.2 3.9 | -28.1 -18.6 280 34 18 7.7 4.2
27000 -25.4 -13.7 285 22 11 7.1 3.9 | -25.8 -14.4 280 32 17 7.7 4.2
26000 -23.3 -9.9 285 21 11 7.1 3.9 | -23.5 -10.3 280 30 16 7.7 4.2
25000 -21.2 -6.2 285 19 10 7.1 3.9 | -21.2 -6.2 285 29 15 7.6 4.2
24000 -19.0 -2.2 290 17 9 7.5 4.1 | -19.0 -2.2 280 26 13 7.4 4.0
23000 -16.8 1.8 295 16 8 7.5 4.1 | -16.8 1.8 280 23 12 7.4 4.1
22000 -14.5 5.9 305 15 8 7.6 4.2 | -14.6 5.7 275 20 10 7.6 4.2
21000 -12.2 10.0 310 15 8 7.8 4.3 | -12.3 9.9 280 19 10 7.9 4.4
20000 -9.9 14.2 315 16 8 7.9 4.3 | -10.0 14.0 285 18 9 8.0 4.4
19500 -8.2 17.2 320 17 9 8.2 4.5 | -8.8 16.2 285 17 9 8.0 4.4
19000 -6.9 19.6 320 18 9 8.6 4.7 | -7.6 18.3 290 17 9 8.5 4.6
18500 -5.6 21.9 320 18 9 8.6 4.7 | -6.3 20.7 290 17 9 8.4 4.6
18000 -4.3 24.3 320 18 9 8.7 4.8 | -5.1 22.8 295 17 9 8.7 4.8
17500 -3.0 26.6 315 18 9 8.8 4.8 | -3.8 25.2 295 18 9 8.9 4.9
17000 -1.8 28.8 315 18 9 8.9 4.9 | -2.5 27.5 300 18 9 8.9 4.9
16500 -0.4 31.3 315 18 9 9.1 5.0 | -1.2 29.8 300 18 9 9.3 5.1
16000 1.0 33.8 315 18 9 9.2 5.0 | 0.2 32.4 300 18 9 9.3 5.1
15500 2.3 36.1 315 18 9 9.1 5.0 | 2.3 36.1 305 18 9 9.4 5.2
15000 3.7 38.7 315 17 9 9.1 5.0 | 3.7 38.7 305 18 9 9.4 5.1
14500 5.0 41.0 310 17 9 9.2 5.1 | 5.1 41.2 305 18 9 9.4 5.1
14000 6.4 43.5 310 17 9 9.3 5.1 | 6.5 43.7 310 18 9 9.4 5.1
13500 7.8 46.0 310 16 8 9.3 5.1 | 7.8 46.0 310 18 9 9.3 5.1
13000 9.2 48.6 310 16 8 9.4 5.2 | 9.2 48.6 310 17 9 9.3 5.1
12500 10.6 51.1 310 16 8 9.4 5.1 | 10.6 51.1 310 17 9 9.4 5.2
12000 12.0 53.6 310 16 8 9.3 5.1 | 12.0 53.6 310 16 8 9.5 5.2
11500 13.3 55.9 310 16 8 9.3 5.1 | 13.3 55.9 315 16 8 9.5 5.2
11000 14.7 58.5 310 17 9 8.9 4.9 | 14.8 58.6 315 15 8 9.4 5.1
10500 16.1 61.0 310 18 9 5.6 3.1 | 16.2 61.2 315 15 8 5.4 3.0
10250 16.4 61.5 310 18 9 6.6 3.6 | 16.5 61.7 315 15 8 6.8 3.7
10000 17.2 63.0 310 18 9 11.8 6.5 | 17.3 63.1 315 15 8 13.0 7.1
9750 18.0 64.4 310 19 10 10.7 5.9 | 18.2 64.8 315 15 8 12.0 6.6
9500 18.8 65.8 305 19 10 9.8 5.4 | 19.1 66.4 315 15 8 9.8 5.4
9250 19.4 66.9 305 19 10 8.0 4.4 | 19.7 67.5 320 15 8 8.2 4.5
9000 20.0 68.0 310 19 10 9.3 5.1 | 20.4 68.7 320 15 8 10.7 5.9
8750 20.8 69.4 305 20 10 10.4 5.7 | 21.2 70.2 320 15 8 11.4 6.2
8500 21.5 70.7 305 20 10 9.5 5.2 | 22.1 71.8 320 14 7 10.1 5.5
8250 22.2 72.0 305 20 10 8.1 4.4 | 22.7 72.9 320 14 7 7.9 4.4
8000 22.8 73.0 305 20 10 8.3 4.6 | 23.4 74.1 320 15 8 9.8 5.4
7750 23.4 74.1 305 20 10 9.7 5.3 | 24.2 75.6 320 14 7 12.3 6.7
7500 24.1 75.4 305 20 10 7.6 4.1 | 25.1 77.2 320 14 7 9.8 5.4
7250 24.5 76.1 305 19 10 5.0 2.7 | 25.7 78.3 325 14 7 7.3 4.0
7000 24.9 76.8 305 19 10 5.3 2.9 | 26.3 79.3 325 14 7 9.3 5.1
6750 25.3 77.5 300 19 10 6.0 3.3 | 27.1 80.8 325 14 7 12.8 7.0
6500 25.7 78.3 295 17 9 5.4 3.0 | 28.0 82.4 325 13 7 11.6 6.3
6250 26.0 78.8 295 15 8 4.9 2.7 | 28.8 83.8 325 13 7 9.9 5.4
6000 26.4 79.5 285 13 7 4.3 2.4 | 29.6 85.3 325 13 7 9.4 5.2
5750 26.7 80.1 280 11 6 7.8 4.3 | 30.3 86.5 325 12 6 14.3 7.9
5500 27.6 81.7 275 9 4 18.1 9.9 | 31.9 89.4 325 11 6 28.2 15.5
07/15/2025 at 1500 MDT | 07/15/2025 at 1800 MDT
|
CAPE... +104.1 LI... -0.4 | CAPE... +57.0 LI... +1.4
CINH... -17.7 K Index... +22.7 | CINH... -65.7 K Index... +19.6
|
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 -63.2 -81.8 270 16 8 -0.0 -0.0 | -63.8 -82.8 275 19 10 0.2 0.1
45000 -60.4 -76.7 270 24 13 6.3 3.5 | -60.5 -76.9 280 27 14 5.9 3.2
40000 -50.7 -59.3 275 28 14 5.6 3.1 | -51.6 -60.9 275 28 15 6.4 3.5
38000 -47.3 -53.1 275 32 16 5.6 3.1 | -47.8 -54.0 280 27 14 6.4 3.5
36000 -44.0 -47.2 275 35 18 5.5 3.0 | -44.0 -47.2 280 26 13 6.3 3.5
34000 -40.2 -40.4 280 37 19 6.4 3.5 | -39.8 -39.6 280 25 13 7.0 3.9
32000 -36.4 -33.5 285 40 21 6.2 3.4 | -35.6 -32.1 280 24 12 6.8 3.8
30000 -31.2 -24.2 285 40 20 8.1 4.5 | -30.3 -22.5 280 24 12 8.1 4.5
29000 -28.8 -19.8 285 39 20 8.1 4.5 | -27.8 -18.0 280 24 12 8.2 4.5
28000 -26.4 -15.5 285 39 20 7.4 4.1 | -25.4 -13.7 285 24 12 7.8 4.3
27000 -24.2 -11.6 280 37 19 7.4 4.1 | -23.1 -9.6 285 24 12 7.8 4.3
26000 -22.0 -7.6 280 36 19 7.4 4.1 | -20.8 -5.4 285 23 12 7.8 4.3
25000 -19.8 -3.6 275 35 18 7.2 3.9 | -18.5 -1.3 290 23 12 7.7 4.2
24000 -17.8 -0.0 280 34 18 6.6 3.6 | -16.3 2.7 290 22 11 7.6 4.2
23000 -15.9 3.4 280 33 17 6.6 3.6 | -14.0 6.8 290 22 11 7.7 4.2
22000 -14.0 6.8 285 32 17 6.8 3.8 | -11.8 10.8 290 21 11 7.4 4.1
21000 -11.9 10.6 285 30 15 7.1 3.9 | -9.7 14.5 295 19 10 6.9 3.8
20000 -9.8 14.4 285 27 14 7.1 3.9 | -7.7 18.1 295 18 9 6.9 3.8
19500 -8.8 16.2 285 26 13 7.0 3.8 | -6.6 20.1 295 17 9 7.0 3.8
19000 -7.6 18.3 285 24 12 8.5 4.6 | -5.6 21.9 295 16 8 6.5 3.5
18500 -6.4 20.5 285 22 11 8.3 4.6 | -4.7 23.5 295 15 8 6.5 3.6
18000 -5.2 22.6 285 20 10 8.5 4.7 | -3.8 25.2 295 14 7 6.7 3.7
17500 -3.9 25.0 285 19 10 8.7 4.8 | -2.2 28.0 290 12 6 7.2 3.9
17000 -2.6 27.3 285 17 9 8.7 4.8 | -1.2 29.8 285 11 6 7.5 4.1
16500 -1.3 29.7 290 16 8 9.1 5.0 | -0.0 32.0 280 10 5 8.0 4.4
16000 0.7 33.3 290 13 7 9.1 5.0 | 1.1 34.0 275 9 4 8.0 4.4
15500 2.1 35.8 295 12 6 9.3 5.1 | 2.3 36.1 265 8 4 8.0 4.4
15000 3.5 38.3 295 11 6 9.3 5.1 | 3.5 38.3 260 7 3 8.1 4.4
14500 4.8 40.6 295 10 5 9.0 4.9 | 4.7 40.5 250 6 3 7.9 4.3
14000 6.2 43.2 295 8 4 9.0 4.9 | 5.8 42.4 245 5 3 7.8 4.3
13500 7.5 45.5 295 7 4 9.4 5.1 | 7.0 44.6 240 5 3 7.9 4.3
13000 8.9 48.0 295 7 3 9.5 5.2 | 8.1 46.6 240 4 2 7.9 4.4
12500 10.3 50.5 300 6 3 9.5 5.2 | 9.3 48.7 240 4 2 8.0 4.4
12000 11.7 53.1 300 6 3 9.4 5.1 | 10.5 50.9 245 4 2 8.2 4.5
11500 13.1 55.6 305 5 3 9.4 5.2 | 11.6 52.9 250 3 2 8.2 4.5
11000 14.6 58.3 305 5 3 9.4 5.2 | 12.9 55.2 260 3 2 8.4 4.6
10500 16.0 60.8 310 5 2 5.9 3.3 | 14.1 57.4 270 3 2 6.3 3.5
10250 16.3 61.3 310 5 2 6.8 3.8 | 14.5 58.1 270 3 2 6.7 3.7
10000 17.1 62.8 310 5 2 12.1 6.6 | 15.2 59.4 275 3 2 9.8 5.4
9750 18.0 64.4 315 5 2 11.2 6.2 | 15.8 60.4 280 4 2 9.2 5.0
9500 18.8 65.8 315 4 2 9.5 5.2 | 16.5 61.7 285 4 2 8.5 4.7
9250 19.4 66.9 320 4 2 8.2 4.5 | 17.1 62.8 290 4 2 6.7 3.7
9000 20.1 68.2 320 4 2 10.4 5.7 | 17.5 63.5 295 4 2 7.4 4.1
8750 20.9 69.6 320 4 2 11.1 6.1 | 18.1 64.6 300 4 2 8.4 4.6
8500 21.7 71.1 325 4 2 10.0 5.5 | 18.7 65.7 300 4 2 8.0 4.4
8250 22.4 72.3 325 4 2 8.0 4.4 | 19.3 66.7 305 5 2 7.4 4.1
8000 23.0 73.4 330 4 2 9.6 5.3 | 19.8 67.6 305 5 3 8.1 4.5
7750 23.8 74.8 330 4 2 11.7 6.4 | 20.4 68.7 305 5 3 9.0 5.0
7500 24.6 76.3 335 4 2 10.0 5.5 | 21.1 70.0 305 5 3 9.1 5.0
7250 25.3 77.5 335 4 2 8.3 4.6 | 21.8 71.2 305 5 2 9.4 5.2
7000 25.9 78.6 340 4 2 9.4 5.2 | 22.5 72.5 300 5 2 9.5 5.2
6750 26.7 80.1 340 4 2 11.5 6.3 | 23.2 73.8 300 5 2 9.4 5.1
6500 27.6 81.7 345 4 2 11.0 6.0 | 23.9 75.0 305 5 3 9.8 5.4
6250 28.4 83.1 345 4 2 10.1 5.5 | 24.6 76.3 300 5 3 10.3 5.7
6000 29.1 84.4 345 4 2 9.9 5.4 | 25.4 77.7 300 5 3 9.8 5.4
5750 29.9 85.8 350 4 2 12.8 7.0 | 26.1 79.0 300 5 3 11.0 6.1
5500 31.1 88.0 345 4 2 20.5 11.2 | 27.1 80.8 300 5 3 16.2 8.9
________________________________________________________________________________
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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