Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
023
UXUS97 KBOU 170115
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1915 MDT Wednesday, July 16, 2025
This forecast is for Thursday, July 17, 2025:
If the trigger temperature of 79.3 F/26.3 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 341 ft/min (1.7 m/s)
Maximum height of thermals.................. 14342 ft MSL (9021 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1130 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10220 ft MSL (4899 ft AGL)
Thermal soaring outlook for Friday 07/18....... Excellent
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....................... 22818 ft MSL (17497 ft AGL)
Wave soaring outlook for Friday 07/18.......... Poor
Remarks...
Sunrise/Sunset.................... 05:46:05 / 20:25:21 MDT
Total possible sunshine........... 14 hr 39 min 17 sec (879 min 17 sec)
Altitude of sun at 13:05:43 MDT... 71.24 degrees
Upper air data from numerical model forecast valid on 07/17/2025 at 0600 MDT
Freezing level.................. 15854 ft MSL (10533 ft AGL)
Convective condensation level... 14075 ft MSL (8754 ft AGL)
Lifted condensation level....... 14252 ft MSL (8932 ft AGL)
Lifted index.................... -4.9
K index......................... +22.4
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 -64.6 -84.3 260 31 16 0.4 0.2 M M M M M
45000 -61.6 -78.9 250 48 25 5.6 3.1 M M M M M
40000 -52.9 -63.2 245 56 29 7.6 4.2 M M M M M
38000 -48.3 -54.9 245 58 30 7.7 4.2 M M M M M
36000 -43.1 -45.6 245 61 31 7.8 4.3 M M M M M
34000 -38.3 -36.9 255 56 29 8.0 4.4 M M M M M
32000 -33.5 -28.3 260 53 27 8.7 4.8 M M M M M
30000 -29.0 -20.2 260 46 24 7.5 4.1 47.3 117.2 12.3 M M
29000 -26.8 -16.2 255 42 22 7.5 4.1 46.5 115.7 11.8 M M
28000 -24.6 -12.3 255 39 20 6.4 3.5 45.7 114.3 11.2 M M
27000 -22.8 -9.0 255 36 18 6.0 3.3 44.1 111.5 10.1 M M
26000 -21.0 -5.8 260 32 17 6.0 3.3 42.7 108.9 9.1 M M
25000 -19.3 -2.7 260 29 15 6.0 3.3 41.4 106.6 8.1 M M
24000 -17.3 0.9 265 25 13 6.7 3.7 40.2 104.4 7.2 M M
23000 -15.3 4.5 270 21 11 6.7 3.7 39.1 102.3 6.4 M M
22000 -13.2 8.2 275 17 9 6.7 3.7 38.1 100.5 5.6 M M
21000 -11.2 11.8 285 16 8 6.9 3.8 37.0 98.5 4.7 M M
20000 -9.1 15.6 290 15 8 6.9 3.8 36.0 96.7 3.9 M M
19500 -8.1 17.4 295 15 8 6.9 3.8 35.5 95.9 3.5 M M
19000 -7.1 19.2 295 15 8 6.9 3.8 35.0 95.1 3.1 M M
18500 -5.6 21.9 300 15 8 6.9 3.8 34.3 93.7 2.4 M M
18000 -4.6 23.7 300 15 8 7.2 4.0 33.8 92.9 2.0 M M
17500 -3.5 25.7 300 14 7 7.3 4.0 33.4 92.1 1.6 M M
17000 -2.5 27.5 300 14 7 7.5 4.1 33.0 91.4 1.2 M M
16500 -1.3 29.7 300 13 7 8.1 4.5 32.7 90.8 0.9 M M
16000 -0.2 31.6 300 13 6 8.0 4.4 32.4 90.4 0.6 M M
15500 1.1 34.0 305 12 6 8.9 4.9 32.2 90.0 0.4 M M
15000 2.4 36.3 305 12 6 8.8 4.8 32.0 89.7 0.2 M M
14500 3.7 38.7 305 11 6 8.7 4.8 31.9 89.4 0.0 M M
14000 4.9 40.8 300 11 6 8.7 4.8 31.7 89.1 -0.2 698 3.5
13500 6.2 43.2 300 11 6 8.5 4.7 31.5 88.8 -0.3 645 3.3
13000 7.4 45.3 295 11 5 8.4 4.6 31.3 88.4 -0.6 593 3.0
12500 8.7 47.7 290 10 5 8.2 4.5 31.1 88.0 -0.8 541 2.8
12000 9.8 49.6 285 10 5 7.7 4.2 30.8 87.4 -1.1 492 2.5
11500 11.0 51.8 280 10 5 7.6 4.2 30.5 86.9 -1.5 444 2.3
11000 11.9 53.4 275 9 5 6.4 3.5 30.0 86.0 -1.9 399 2.0
10500 12.9 55.2 265 9 5 5.3 2.9 29.5 85.1 -2.5 357 1.8
10250 13.1 55.6 265 9 4 3.4 1.9 29.1 84.3 -2.9 341 1.7
10000 13.4 56.1 260 8 4 4.7 2.6 28.6 83.5 -3.4 326 1.7
9750 13.7 56.7 255 8 4 5.7 3.1 28.3 82.9 -3.8 308 1.6
9500 14.1 57.4 250 8 4 4.8 2.6 27.9 82.3 -4.2 291 1.5
9250 14.3 57.7 245 8 4 2.8 1.6 27.5 81.4 -4.7 276 1.4
9000 14.4 57.9 245 8 4 1.2 0.7 26.9 80.3 -5.4 266 1.4
8750 14.4 57.9 240 8 4 1.0 0.5 26.2 79.1 -6.1 259 1.3
8500 14.4 57.9 235 8 4 0.7 0.4 25.5 77.9 -6.9 252 1.3
8250 14.4 57.9 230 8 4 -0.1 -0.0 24.8 76.6 -7.7 245 1.2
8000 14.3 57.7 225 8 4 -0.2 -0.1 24.0 75.2 -8.5 240 1.2
7750 14.2 57.6 225 7 4 -0.2 -0.1 23.2 73.8 -9.3 234 1.2
7500 14.2 57.6 220 7 4 -0.1 -0.1 22.5 72.4 -10.1 229 1.2
7250 14.1 57.4 220 7 3 -0.0 -0.0 21.7 71.1 -10.9 223 1.1
7000 14.1 57.4 220 6 3 -0.0 -0.0 21.0 69.7 -11.7 217 1.1
6750 14.1 57.4 215 5 3 0.5 0.3 20.2 68.4 -12.5 210 1.1
6500 14.1 57.4 215 5 2 1.2 0.7 19.6 67.2 -13.2 201 1.0
6250 14.2 57.6 225 4 2 1.3 0.7 18.9 66.1 -13.9 192 1.0
6000 14.2 57.6 235 3 1 1.3 0.7 18.3 64.9 -14.6 182 0.9
5750 14.3 57.7 255 2 1 1.9 1.1 17.7 63.8 -15.3 173 0.9
5500 14.5 58.1 260 1 1 2.7 1.5 17.1 62.8 -15.9 160 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/17/2025 at 0900 MDT | 07/17/2025 at 1200 MDT
|
CAPE... +468.0 LI... -2.0 | CAPE... +839.0 LI... -3.6
CINH... -256.9 K Index... +20.4 | CINH... -67.7 K Index... +18.5
|
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 -65.0 -85.0 265 29 15 0.8 0.5 | -64.7 -84.5 255 29 15 0.8 0.4
45000 -61.4 -78.5 255 44 22 5.8 3.2 | -61.3 -78.3 250 42 22 5.5 3.0
40000 -52.4 -62.3 240 53 27 7.0 3.9 | -52.7 -62.9 245 51 26 7.1 3.9
38000 -48.2 -54.8 240 53 27 7.1 3.9 | -48.4 -55.1 245 50 26 7.1 3.9
36000 -43.4 -46.1 240 53 27 7.3 4.0 | -43.6 -46.5 245 49 25 7.5 4.1
34000 -38.7 -37.7 245 50 26 7.9 4.3 | -38.8 -37.8 245 45 23 8.0 4.4
32000 -33.9 -29.0 250 47 24 8.6 4.7 | -34.0 -29.2 245 42 22 8.7 4.8
30000 -29.3 -20.7 255 43 22 7.7 4.2 | -29.1 -20.4 245 40 21 8.3 4.5
29000 -27.0 -16.6 255 41 21 7.7 4.2 | -26.6 -15.9 245 40 20 8.3 4.6
28000 -24.8 -12.6 260 39 20 6.7 3.7 | -24.3 -11.7 245 38 20 6.5 3.6
27000 -22.9 -9.2 260 35 18 6.3 3.5 | -22.4 -8.3 250 35 18 6.1 3.4
26000 -21.0 -5.8 255 32 17 6.3 3.5 | -20.6 -5.1 250 32 17 6.2 3.4
25000 -19.2 -2.6 255 29 15 6.3 3.5 | -18.8 -1.8 255 29 15 6.2 3.4
24000 -17.2 1.0 255 26 13 6.5 3.5 | -17.0 1.4 255 27 14 6.1 3.4
23000 -15.3 4.5 260 23 12 6.5 3.5 | -15.1 4.8 255 24 12 6.2 3.4
22000 -13.4 7.9 260 20 10 6.5 3.5 | -13.3 8.1 255 21 11 6.2 3.4
21000 -11.4 11.5 265 18 9 6.5 3.6 | -11.4 11.5 255 19 10 6.5 3.6
20000 -9.0 15.8 270 15 8 6.5 3.6 | -9.4 15.1 260 18 9 6.5 3.6
19500 -8.1 17.4 270 14 7 6.6 3.6 | -8.0 17.6 260 17 9 6.7 3.7
19000 -7.0 19.4 275 14 7 7.0 3.8 | -6.9 19.6 260 17 9 6.9 3.8
18500 -6.0 21.2 280 13 7 6.9 3.8 | -5.9 21.4 265 16 8 6.8 3.8
18000 -5.0 23.0 285 13 7 7.3 4.0 | -4.9 23.2 270 15 8 7.6 4.2
17500 -3.9 25.0 290 12 6 7.4 4.1 | -3.7 25.3 275 15 8 7.7 4.2
17000 -2.8 27.0 290 12 6 7.6 4.2 | -2.6 27.3 280 14 7 7.8 4.3
16500 -1.7 28.9 295 12 6 8.1 4.4 | -1.4 29.5 285 14 7 8.0 4.4
16000 -0.5 31.1 300 12 6 8.0 4.4 | -0.3 31.5 290 14 7 7.9 4.4
15500 0.7 33.3 300 12 6 8.8 4.8 | 1.0 33.8 290 13 7 8.8 4.8
15000 2.0 35.6 305 11 6 8.8 4.8 | 2.2 36.0 295 13 7 8.7 4.8
14500 3.3 37.9 305 11 6 9.0 4.9 | 3.5 38.3 300 12 6 9.0 5.0
14000 4.6 40.3 305 11 6 9.0 4.9 | 4.9 40.8 300 12 6 9.1 5.0
13500 6.0 42.8 310 11 6 9.1 5.0 | 6.2 43.2 305 11 6 9.2 5.0
13000 7.3 45.1 310 11 6 9.1 5.0 | 7.6 45.7 305 11 5 9.2 5.1
12500 8.6 47.5 310 11 5 9.0 4.9 | 8.9 48.0 310 10 5 9.2 5.1
12000 9.9 49.8 305 10 5 8.7 4.8 | 10.3 50.5 310 9 5 9.2 5.1
11500 11.2 52.2 305 10 5 8.6 4.7 | 11.6 52.9 315 9 5 9.1 5.0
11000 12.4 54.3 300 10 5 7.6 4.2 | 13.0 55.4 315 8 4 8.5 4.6
10500 13.5 56.3 295 9 5 4.5 2.5 | 14.3 57.7 320 8 4 4.1 2.3
10250 13.7 56.7 295 9 5 3.4 1.9 | 14.4 57.9 320 8 4 5.0 2.7
10000 14.1 57.4 295 9 4 7.5 4.1 | 15.1 59.2 320 7 4 11.4 6.2
9750 14.7 58.5 290 8 4 7.5 4.1 | 15.9 60.6 320 6 3 10.3 5.7
9500 15.2 59.4 285 8 4 6.5 3.6 | 16.6 61.9 320 6 3 8.2 4.5
9250 15.5 59.9 285 7 4 3.7 2.0 | 17.0 62.6 320 5 3 4.0 2.2
9000 15.7 60.3 285 7 4 3.2 1.8 | 17.3 63.1 320 5 2 4.9 2.7
8750 15.9 60.6 280 6 3 4.1 2.2 | 17.6 63.7 315 4 2 6.1 3.3
8500 16.2 61.2 275 6 3 3.3 1.8 | 18.0 64.4 305 3 1 5.5 3.0
8250 16.3 61.3 275 5 3 2.4 1.3 | 18.3 64.9 305 1 1 4.7 2.6
8000 16.4 61.5 270 5 3 2.0 1.1 | 18.6 65.5 000 0 0 5.7 3.1
7750 16.4 61.5 265 4 2 1.6 0.9 | 19.0 66.2 140 1 0 7.1 3.9
7500 16.5 61.7 255 4 2 1.6 0.9 | 19.5 67.1 140 2 1 6.7 3.7
7250 16.5 61.7 250 4 2 1.7 0.9 | 19.9 67.8 130 2 1 6.0 3.3
7000 16.6 61.9 245 3 2 1.8 1.0 | 20.3 68.5 125 2 1 7.2 3.9
6750 16.7 62.1 230 3 2 3.5 1.9 | 20.9 69.6 125 2 1 10.5 5.8
6500 17.0 62.6 220 3 2 4.5 2.5 | 21.7 71.1 125 2 1 10.6 5.8
6250 17.3 63.1 220 3 1 4.6 2.5 | 22.3 72.1 125 2 1 9.4 5.2
6000 17.5 63.5 215 2 1 3.7 2.0 | 23.0 73.4 120 2 1 9.0 4.9
5750 17.9 64.2 200 1 1 9.7 5.3 | 23.8 74.8 120 2 1 15.3 8.4
5500 19.0 66.2 195 1 1 22.0 12.1 | 25.4 77.7 120 2 1 28.4 15.6
07/17/2025 at 1500 MDT | 07/17/2025 at 1800 MDT
|
CAPE... +191.9 LI... -2.0 | CAPE... +565.8 LI... -3.0
CINH... -13.9 K Index... +23.5 | CINH... -47.6 K Index... +28.8
|
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 -65.1 -85.2 245 31 16 0.5 0.3 | -65.7 -86.3 250 33 17 0.4 0.2
45000 -61.8 -79.2 245 43 22 6.0 3.3 | -62.2 -80.0 240 44 23 6.5 3.6
40000 -52.0 -61.6 245 47 24 7.6 4.2 | -51.6 -60.9 235 44 23 8.0 4.4
38000 -47.5 -53.5 245 47 24 7.6 4.2 | -46.8 -52.2 235 45 23 8.0 4.4
36000 -42.9 -45.2 245 48 24 7.6 4.2 | -42.0 -43.6 240 45 23 8.0 4.4
34000 -38.2 -36.8 245 44 23 7.8 4.3 | -37.3 -35.1 240 45 23 7.9 4.3
32000 -33.5 -28.3 245 40 21 7.6 4.2 | -32.5 -26.5 245 44 23 7.8 4.3
30000 -28.7 -19.7 245 37 19 8.2 4.5 | -27.4 -17.3 250 40 21 7.7 4.2
29000 -25.7 -14.3 245 35 18 8.2 4.5 | -25.1 -13.2 250 38 20 7.8 4.3
28000 -23.4 -10.1 240 34 17 6.0 3.3 | -22.9 -9.2 255 37 19 6.1 3.4
27000 -21.6 -6.9 245 32 17 6.3 3.4 | -21.1 -6.0 255 34 18 6.4 3.5
26000 -19.7 -3.5 245 31 16 6.3 3.5 | -19.2 -2.6 255 32 16 6.4 3.5
25000 -17.9 -0.2 245 30 15 6.4 3.5 | -17.3 0.9 255 30 15 6.2 3.4
24000 -16.0 3.2 250 27 14 6.6 3.6 | -15.6 3.9 265 27 14 5.8 3.2
23000 -14.0 6.8 255 25 13 6.6 3.6 | -13.8 7.2 280 25 13 5.8 3.2
22000 -12.1 10.2 260 22 11 6.1 3.4 | -12.1 10.2 295 24 12 6.1 3.3
21000 -10.4 13.3 265 20 11 5.6 3.1 | -10.2 13.6 300 24 13 6.4 3.5
20000 -8.7 16.3 280 19 10 5.6 3.1 | -8.3 17.1 310 25 13 6.5 3.6
19500 -7.9 17.8 285 19 10 5.6 3.1 | -7.4 18.7 310 26 13 6.4 3.5
19000 -6.9 19.6 285 19 10 7.5 4.1 | -6.4 20.5 315 25 13 7.7 4.2
18500 -5.8 21.6 290 19 10 7.3 4.0 | -5.3 22.5 315 24 12 7.6 4.2
18000 -4.7 23.5 290 19 10 7.7 4.2 | -4.3 24.3 315 23 12 7.6 4.2
17500 -3.5 25.7 290 19 10 8.1 4.4 | -3.2 26.2 315 20 10 7.6 4.2
17000 -2.3 27.9 290 18 9 8.1 4.4 | -2.1 28.2 315 18 9 7.6 4.1
16500 -1.1 30.0 290 18 9 8.4 4.6 | -0.9 30.4 315 15 8 8.2 4.5
16000 0.1 32.2 295 17 9 8.4 4.6 | 0.3 32.5 310 13 7 8.2 4.5
15500 1.3 34.3 295 15 8 8.3 4.6 | 2.1 35.8 310 9 5 8.3 4.5
15000 2.5 36.5 295 14 7 8.3 4.5 | 3.3 37.9 305 6 3 8.3 4.5
14500 4.3 39.7 290 11 6 8.5 4.7 | 4.5 40.1 290 3 2 8.3 4.5
14000 5.5 41.9 290 9 4 8.5 4.7 | 5.6 42.1 235 2 1 8.3 4.5
13500 6.8 44.2 285 7 3 8.5 4.7 | 6.8 44.2 180 3 2 8.6 4.7
13000 8.0 46.4 280 5 3 8.6 4.7 | 8.1 46.6 170 5 2 8.7 4.8
12500 9.3 48.7 265 4 2 8.7 4.8 | 9.3 48.7 170 6 3 8.9 4.9
12000 10.6 51.1 245 3 2 8.8 4.8 | 10.7 51.3 165 7 4 9.1 5.0
11500 11.9 53.4 215 3 1 8.9 4.9 | 12.0 53.6 165 8 4 9.1 5.0
11000 13.2 55.8 195 3 2 8.9 4.9 | 13.3 55.9 165 9 5 8.9 4.9
10500 14.6 58.3 175 4 2 4.9 2.7 | 14.7 58.5 165 10 5 5.3 2.9
10250 14.8 58.6 175 4 2 6.4 3.5 | 14.9 58.8 165 10 5 6.2 3.4
10000 15.6 60.1 170 4 2 12.5 6.9 | 15.7 60.3 165 11 6 11.6 6.4
9750 16.4 61.5 165 4 2 11.7 6.4 | 16.5 61.7 165 12 6 10.6 5.8
9500 17.2 63.0 165 5 2 9.0 4.9 | 17.3 63.1 165 12 6 9.3 5.1
9250 17.7 63.9 160 5 2 7.1 3.9 | 17.8 64.0 165 13 7 7.3 4.0
9000 18.4 65.1 160 5 2 10.6 5.8 | 18.4 65.1 165 13 7 8.8 4.8
8750 19.2 66.6 160 5 3 11.9 6.5 | 19.1 66.4 165 14 7 9.8 5.4
8500 20.1 68.2 155 5 3 9.9 5.4 | 19.8 67.6 165 15 8 8.6 4.7
8250 20.6 69.1 155 5 3 6.9 3.8 | 20.3 68.5 165 16 8 7.0 3.8
8000 21.2 70.2 155 5 3 10.0 5.5 | 20.9 69.6 170 16 8 7.1 3.9
7750 22.1 71.8 155 6 3 13.0 7.1 | 21.4 70.5 170 18 9 7.6 4.2
7500 23.0 73.4 150 6 3 10.0 5.5 | 21.9 71.4 170 20 10 7.3 4.0
7250 23.6 74.5 150 6 3 7.9 4.3 | 22.4 72.3 170 20 11 7.0 3.8
7000 24.2 75.6 150 6 3 9.6 5.3 | 22.9 73.2 170 21 11 7.5 4.1
6750 25.0 77.0 150 6 3 11.8 6.5 | 23.5 74.3 170 22 11 8.8 4.8
6500 25.9 78.6 150 6 3 10.7 5.9 | 24.1 75.4 170 23 12 9.2 5.0
6250 26.6 79.9 145 6 3 9.7 5.3 | 24.7 76.5 170 22 12 9.1 5.0
6000 27.4 81.3 145 6 3 9.3 5.1 | 25.4 77.7 175 22 11 8.6 4.7
5750 28.2 82.8 145 6 3 15.6 8.5 | 26.1 79.0 175 21 11 12.4 6.8
5500 29.8 85.6 145 6 3 28.4 15.6 | 27.3 81.1 175 19 10 21.1 11.6
________________________________________________________________________________
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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