Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
933
UXUS97 KBOU 051231
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0630 MDT Thursday, June 5, 2025
This forecast is for Thursday, June 5, 2025:
If the trigger temperature of 66.1 F/18.9 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 762 ft/min (3.9 m/s)
Maximum height of thermals.................. 12471 ft MSL (7167 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 1130 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 9469 ft MSL (4165 ft AGL)
Thermal soaring outlook for Friday 06/06....... Fair
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....................... 40259 ft MSL (34955 ft AGL)
Wave soaring outlook for Friday 06/06.......... Fair
Remarks...
Sunrise/Sunset.................... 05:31:51 / 20:24:21 MDT
Total possible sunshine........... 14 hr 52 min 30 sec (892 min 30 sec)
Altitude of sun at 12:58:06 MDT... 72.86 degrees
Upper air data from numerical model forecast valid on 06/05/2025 at 0600 MDT
Freezing level.................. 12812 ft MSL (7508 ft AGL)
Convective condensation level... 10302 ft MSL (4998 ft AGL)
Lifted condensation level....... 11164 ft MSL (5860 ft AGL)
Lifted index.................... -3.4
K index......................... +28.9
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 -58.9 -74.0 255 47 24 1.0 0.6 M M M M M
45000 -57.3 -71.1 250 57 29 0.6 0.4 M M M M M
40000 -56.4 -69.5 250 63 32 0.1 0.1 M M M M M
38000 -53.7 -64.7 250 60 31 5.0 2.8 M M M M M
36000 -50.6 -59.1 250 57 29 5.1 2.8 M M M M M
34000 -46.8 -52.2 250 55 28 7.9 4.3 M M M M M
32000 -41.5 -42.7 250 54 28 7.9 4.3 M M M M M
30000 -36.5 -33.7 250 51 26 8.4 4.6 39.2 102.6 12.9 M M
29000 -34.0 -29.2 255 49 25 8.4 4.6 38.7 101.6 12.6 M M
28000 -31.5 -24.7 255 47 24 8.4 4.6 38.3 100.9 12.5 M M
27000 -29.1 -20.4 260 43 22 7.5 4.1 37.5 99.6 12.0 M M
26000 -26.9 -16.4 260 40 20 7.5 4.1 36.6 97.9 11.4 M M
25000 -24.7 -12.5 255 36 18 7.5 4.1 35.8 96.4 10.9 M M
24000 -22.5 -8.5 255 32 16 7.7 4.2 35.0 95.0 10.3 M M
23000 -20.2 -4.4 255 28 15 7.7 4.2 34.2 93.6 9.7 M M
22000 -17.9 -0.2 250 25 13 7.7 4.2 33.5 92.3 9.3 M M
21000 -15.7 3.7 245 23 12 6.7 3.7 32.7 90.8 8.6 M M
20000 -13.8 7.2 245 23 12 6.7 3.7 31.5 88.8 7.7 M M
19500 -12.8 9.0 245 22 11 6.8 3.7 31.0 87.9 7.3 M M
19000 -11.8 10.8 245 22 11 6.8 3.7 30.6 87.0 6.9 M M
18500 -11.0 12.2 245 21 11 4.6 2.5 29.9 85.7 6.3 M M
18000 -10.3 13.5 240 20 10 4.9 2.7 29.0 84.2 5.5 M M
17500 -9.6 14.7 240 19 10 5.2 2.9 28.2 82.7 4.8 M M
17000 -8.8 16.2 240 18 9 5.5 3.0 27.4 81.4 4.1 M M
16500 -7.6 18.3 240 17 9 7.1 3.9 26.4 79.6 3.2 M M
16000 -6.5 20.3 240 16 8 7.7 4.2 26.1 79.0 2.9 M M
15500 -5.4 22.3 245 15 8 7.5 4.1 25.8 78.4 2.5 M M
15000 -4.3 24.3 250 14 7 7.0 3.9 25.3 77.6 2.1 M M
14500 -3.3 26.1 255 14 7 7.1 3.9 24.9 76.8 1.7 M M
14000 -2.3 27.9 260 13 7 7.0 3.9 24.4 76.0 1.2 M M
13500 -1.3 29.7 260 13 7 7.0 3.8 24.0 75.2 0.8 M M
13000 -0.3 31.5 265 13 6 7.4 4.1 23.6 74.4 0.4 M M
12500 0.8 33.4 265 12 6 7.4 4.1 23.2 73.7 -0.0 560 2.8
12000 1.8 35.2 260 12 6 7.1 3.9 22.8 73.0 -0.4 514 2.6
11500 2.9 37.2 260 11 6 7.1 3.9 22.4 72.2 -0.9 468 2.4
11000 3.9 39.0 255 11 6 7.2 3.9 21.9 71.5 -1.3 423 2.1
10500 4.9 40.8 250 11 6 7.9 4.3 21.5 70.7 -1.8 378 1.9
10250 5.4 41.7 250 11 6 4.3 2.3 21.3 70.4 -2.0 355 1.8
10000 5.6 42.1 250 11 6 4.4 2.4 20.8 69.4 -2.5 342 1.7
9750 6.1 43.0 245 11 6 8.1 4.4 20.6 69.0 -2.8 319 1.6
9500 6.6 43.9 245 11 6 7.4 4.1 20.4 68.7 -3.0 296 1.5
9250 7.1 44.8 245 11 6 6.4 3.5 20.2 68.4 -3.2 273 1.4
9000 7.5 45.5 245 11 5 5.6 3.0 19.9 67.8 -3.5 254 1.3
8750 8.0 46.4 240 10 5 6.4 3.5 19.6 67.3 -3.8 234 1.2
8500 8.4 47.1 240 10 5 6.4 3.5 19.3 66.8 -4.1 213 1.1
8250 8.8 47.8 240 10 5 5.5 3.0 19.0 66.3 -4.5 193 1.0
8000 9.2 48.6 235 10 5 4.3 2.4 18.7 65.6 -4.9 176 0.9
7750 9.5 49.1 225 10 5 3.5 1.9 18.2 64.8 -5.3 160 0.8
7500 9.7 49.5 220 11 6 3.4 1.8 17.7 63.9 -5.8 146 0.7
7250 9.9 49.8 210 11 6 4.4 2.4 17.3 63.1 -6.3 130 0.7
7000 10.3 50.5 205 11 6 4.6 2.5 16.9 62.4 -6.7 114 0.6
6750 10.6 51.1 200 11 6 5.1 2.8 16.5 61.7 -7.2 96 0.5
6500 10.9 51.6 195 11 6 4.4 2.4 16.1 61.1 -7.5 78 0.4
6250 11.2 52.2 190 9 5 3.3 1.8 15.7 60.2 -8.1 64 0.3
6000 11.4 52.5 190 7 3 3.5 1.9 15.2 59.4 -8.6 50 0.3
5750 11.6 52.9 185 4 2 3.4 1.9 14.7 58.5 -9.1 37 0.2
5500 11.8 53.2 175 2 1 4.5 2.5 14.3 57.7 -9.6 22 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/05/2025 at 0900 MDT | 06/05/2025 at 1200 MDT
|
CAPE... +276.4 LI... -1.4 | CAPE... +702.7 LI... -3.4
CINH... -56.1 K Index... +21.2 | CINH... -7.8 K Index... +13.9
|
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 -58.5 -73.3 250 47 24 1.4 0.7 | -58.9 -74.0 250 48 25 1.3 0.7
45000 -56.7 -70.1 250 54 28 0.3 0.2 | -57.1 -70.8 245 58 30 0.7 0.4
40000 -56.2 -69.2 250 69 36 -0.3 -0.1 | -56.0 -68.8 245 68 35 0.2 0.1
38000 -53.5 -64.3 250 64 33 5.1 2.8 | -53.1 -63.6 245 65 34 5.4 3.0
36000 -50.4 -58.7 245 57 29 5.1 2.8 | -49.5 -57.1 245 60 31 5.4 3.0
34000 -46.2 -51.2 240 52 27 7.1 3.9 | -45.8 -50.4 245 54 28 6.6 3.6
32000 -41.9 -43.4 235 51 26 7.1 3.9 | -41.9 -43.4 240 48 25 6.5 3.6
30000 -37.0 -34.6 240 48 25 9.0 4.9 | -37.1 -34.8 235 42 22 9.2 5.0
29000 -34.3 -29.7 245 47 24 9.0 4.9 | -34.3 -29.7 235 40 21 9.2 5.0
28000 -31.6 -24.9 250 46 24 9.0 4.9 | -31.6 -24.9 235 38 20 9.2 5.1
27000 -29.2 -20.6 250 45 23 7.7 4.2 | -29.1 -20.4 240 37 19 7.5 4.1
26000 -26.9 -16.4 250 43 22 7.7 4.2 | -26.9 -16.4 245 37 19 7.5 4.1
25000 -24.6 -12.3 255 41 21 7.7 4.2 | -24.7 -12.5 250 36 19 7.5 4.1
24000 -22.4 -8.3 255 39 20 7.4 4.1 | -22.5 -8.5 250 35 18 7.4 4.0
23000 -20.2 -4.4 255 36 18 7.5 4.1 | -20.3 -4.5 250 33 17 7.4 4.1
22000 -17.9 -0.2 255 33 17 7.4 4.1 | -18.1 -0.6 250 30 16 7.4 4.0
21000 -15.9 3.4 255 30 15 6.3 3.5 | -16.2 2.8 250 28 15 5.6 3.0
20000 -14.0 6.8 250 27 14 6.3 3.5 | -14.5 5.9 250 27 14 5.6 3.0
19500 -13.1 8.4 245 25 13 6.3 3.5 | -13.7 7.3 250 27 14 5.6 3.0
19000 -12.1 10.2 240 24 12 6.4 3.5 | -12.9 8.8 250 26 13 5.6 3.1
18500 -11.3 11.7 240 22 11 5.5 3.0 | -11.6 11.1 250 24 12 5.3 2.9
18000 -10.5 13.1 245 20 10 5.6 3.1 | -10.8 12.6 255 22 12 5.3 2.9
17500 -9.3 15.3 255 17 9 5.1 2.8 | -9.8 14.4 255 21 11 7.9 4.3
17000 -8.5 16.7 265 15 8 5.1 2.8 | -8.6 16.5 255 19 10 7.7 4.2
16500 -7.7 18.1 275 14 7 6.9 3.8 | -7.5 18.5 260 17 9 7.0 3.8
16000 -6.6 20.1 285 14 7 7.5 4.1 | -6.5 20.3 270 18 9 6.8 3.8
15500 -5.5 22.1 290 14 7 7.6 4.2 | -5.5 22.1 280 20 10 7.3 4.0
15000 -4.3 24.3 295 14 7 7.8 4.3 | -4.3 24.3 285 21 11 8.2 4.5
14500 -3.2 26.2 295 15 8 7.8 4.3 | -3.1 26.4 290 22 11 8.2 4.5
14000 -2.0 28.4 295 15 8 7.9 4.3 | -1.9 28.6 295 22 12 7.4 4.0
13500 -0.9 30.4 295 15 8 8.1 4.4 | -0.9 30.4 295 23 12 7.4 4.0
13000 0.3 32.5 295 15 8 7.5 4.1 | 0.3 32.5 300 22 11 8.2 4.5
12500 1.4 34.5 295 15 8 7.5 4.1 | 1.4 34.5 300 21 11 8.1 4.4
12000 2.4 36.3 295 15 7 7.8 4.3 | 2.6 36.7 305 20 10 8.7 4.8
11500 3.6 38.5 295 14 7 7.9 4.3 | 3.8 38.8 305 20 10 8.9 4.9
11000 4.6 40.3 295 13 7 7.3 4.0 | 5.0 41.0 310 19 10 7.1 3.9
10500 5.7 42.3 295 12 6 7.9 4.3 | 6.0 42.8 310 18 9 7.5 4.1
10250 6.2 43.2 295 12 6 4.4 2.4 | 6.5 43.7 310 17 9 5.0 2.8
10000 6.4 43.5 295 11 6 4.9 2.7 | 6.8 44.2 310 17 9 6.1 3.3
9750 7.0 44.6 295 11 6 8.6 4.7 | 7.4 45.3 310 15 8 9.4 5.1
9500 7.5 45.5 295 11 6 8.0 4.4 | 8.0 46.4 310 14 7 8.7 4.8
9250 8.1 46.6 295 11 5 6.8 3.7 | 8.6 47.5 310 13 7 8.4 4.6
9000 8.5 47.3 295 10 5 5.7 3.1 | 9.1 48.4 315 12 6 7.2 4.0
8750 8.9 48.0 295 10 5 6.4 3.5 | 9.6 49.3 315 11 6 7.0 3.8
8500 9.4 48.9 300 10 5 6.3 3.4 | 10.1 50.2 320 10 5 7.1 3.9
8250 9.8 49.6 300 10 5 5.7 3.1 | 10.6 51.1 325 9 4 6.7 3.7
8000 10.1 50.2 300 10 5 4.8 2.7 | 11.0 51.8 340 7 4 6.8 3.7
7750 10.4 50.7 300 9 5 4.4 2.4 | 11.4 52.5 350 7 3 7.1 3.9
7500 10.7 51.3 300 9 4 3.6 2.0 | 11.9 53.4 360 7 3 8.1 4.4
7250 10.9 51.6 300 8 4 2.1 1.2 | 12.5 54.5 005 7 3 10.0 5.5
7000 10.9 51.6 300 7 3 1.8 1.0 | 13.3 55.9 005 6 3 10.6 5.8
6750 11.0 51.8 300 5 3 2.1 1.1 | 14.0 57.2 005 6 3 9.4 5.1
6500 11.1 52.0 300 4 2 5.5 3.0 | 14.7 58.5 005 6 3 10.3 5.6
6250 11.7 53.1 300 4 2 8.5 4.7 | 15.6 60.1 005 6 3 12.1 6.6
6000 12.2 54.0 305 3 2 7.1 3.9 | 16.4 61.5 005 6 3 10.9 6.0
5750 12.7 54.9 305 3 2 10.3 5.6 | 17.3 63.1 005 6 3 13.3 7.3
5500 13.8 56.8 305 3 2 20.0 11.0 | 18.6 65.5 005 6 3 23.0 12.6
06/05/2025 at 1500 MDT | 06/05/2025 at 1800 MDT
|
CAPE... +672.4 LI... -3.0 | CAPE... +644.8 LI... -2.3
CINH... -1.2 K Index... +29.0 | CINH... -5.8 K Index... +31.0
|
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 -59.5 -75.1 250 54 28 1.0 0.6 | -59.3 -74.7 255 54 28 0.9 0.5
45000 -57.9 -72.2 245 64 33 1.6 0.9 | -57.7 -71.9 250 70 36 1.4 0.8
40000 -55.3 -67.5 250 68 35 2.6 1.4 | -55.7 -68.3 250 72 37 1.0 0.5
38000 -52.6 -62.7 245 64 33 4.7 2.6 | -53.3 -63.9 250 64 33 4.3 2.3
36000 -49.7 -57.5 245 59 30 4.7 2.6 | -50.4 -58.7 245 53 27 4.3 2.3
34000 -46.2 -51.2 240 53 28 6.9 3.8 | -46.6 -51.9 245 48 25 7.8 4.3
32000 -42.0 -43.6 235 48 25 6.9 3.8 | -41.9 -43.4 235 45 23 7.8 4.3
30000 -37.1 -34.8 235 43 22 9.4 5.2 | -36.9 -34.4 240 44 22 8.7 4.8
29000 -34.3 -29.7 235 41 21 9.4 5.2 | -34.3 -29.7 240 43 22 8.7 4.8
28000 -30.8 -23.4 240 38 19 9.7 5.3 | -31.7 -25.1 245 42 22 8.8 4.8
27000 -28.6 -19.5 245 37 19 6.9 3.8 | -29.2 -20.6 250 40 21 7.9 4.3
26000 -26.5 -15.7 250 38 19 6.9 3.8 | -26.9 -16.4 250 37 19 7.9 4.3
25000 -24.4 -11.9 260 39 20 6.9 3.8 | -24.5 -12.1 255 34 17 7.9 4.3
24000 -22.4 -8.3 265 37 19 6.7 3.7 | -22.3 -8.1 260 31 16 7.3 4.0
23000 -20.4 -4.7 265 32 16 6.7 3.7 | -20.1 -4.2 260 30 15 7.3 4.0
22000 -18.4 -1.1 270 26 13 6.7 3.7 | -17.9 -0.2 265 28 15 7.3 4.0
21000 -16.3 2.7 270 25 13 7.0 3.9 | -15.8 3.6 265 26 13 7.1 3.9
20000 -14.3 6.3 265 29 15 7.1 3.9 | -13.7 7.3 270 23 12 7.2 3.9
19500 -13.2 8.2 260 30 16 7.1 3.9 | -12.7 9.1 270 21 11 7.2 3.9
19000 -12.2 10.0 260 32 16 6.9 3.8 | -11.2 11.8 270 19 10 5.8 3.2
18500 -11.3 11.7 260 32 16 6.2 3.4 | -10.4 13.3 280 18 9 5.2 2.9
18000 -10.4 13.3 260 31 16 6.3 3.5 | -9.7 14.5 290 18 9 5.2 2.9
17500 -9.6 14.7 260 30 15 5.8 3.2 | -8.8 16.2 295 16 8 6.3 3.5
17000 -8.7 16.3 265 28 15 5.8 3.2 | -7.9 17.8 295 13 7 6.2 3.4
16500 -7.9 17.8 270 27 14 6.1 3.4 | -7.0 19.4 300 10 5 6.5 3.6
16000 -6.9 19.6 275 26 14 6.8 3.8 | -6.0 21.2 305 8 4 6.6 3.6
15500 -5.9 21.4 285 25 13 6.8 3.7 | -5.1 22.8 310 6 3 6.6 3.6
15000 -4.9 23.2 285 25 13 8.3 4.6 | -4.1 24.6 330 5 2 6.6 3.6
14500 -3.1 26.4 290 24 12 8.1 4.5 | -3.2 26.2 355 4 2 6.7 3.7
14000 -2.0 28.4 295 22 11 7.8 4.3 | -2.2 28.0 010 5 3 6.9 3.8
13500 -0.9 30.4 295 20 10 7.9 4.3 | -1.2 29.8 020 6 3 6.9 3.8
13000 0.3 32.5 300 18 9 8.4 4.6 | -0.2 31.6 025 7 3 7.0 3.8
12500 1.5 34.7 300 16 8 8.4 4.6 | 0.8 33.4 025 7 4 7.0 3.9
12000 2.8 37.0 305 13 7 8.0 4.4 | 1.8 35.2 025 7 4 7.0 3.9
11500 4.0 39.2 315 11 6 8.1 4.4 | 2.8 37.0 025 7 3 7.0 3.8
11000 5.1 41.2 330 8 4 7.9 4.3 | 3.8 38.8 025 6 3 8.1 4.5
10500 6.2 43.2 350 7 3 8.5 4.6 | 5.0 41.0 020 6 3 8.7 4.8
10250 6.7 44.1 005 6 3 6.0 3.3 | 5.6 42.1 020 5 3 5.9 3.2
10000 7.1 44.8 005 6 3 7.5 4.1 | 5.9 42.6 020 5 3 7.0 3.8
9750 7.8 46.0 010 6 3 11.0 6.0 | 6.7 44.1 020 5 2 10.4 5.7
9500 8.6 47.5 010 6 3 10.3 5.7 | 7.4 45.3 020 4 2 9.8 5.4
9250 9.3 48.7 015 6 3 9.1 5.0 | 8.1 46.6 020 3 2 8.5 4.7
9000 9.9 49.8 015 6 3 9.2 5.0 | 8.6 47.5 020 3 1 7.5 4.1
8750 10.6 51.1 015 6 3 10.6 5.8 | 9.2 48.6 015 2 1 8.3 4.6
8500 11.4 52.5 015 6 3 10.2 5.6 | 9.8 49.6 005 1 1 8.1 4.4
8250 12.2 54.0 015 6 3 10.2 5.6 | 10.4 50.7 315 1 0 9.0 4.9
8000 12.9 55.2 015 6 3 10.1 5.5 | 11.1 52.0 235 1 1 8.7 4.7
7750 13.7 56.7 015 6 3 10.2 5.6 | 11.6 52.9 220 2 1 6.5 3.5
7500 14.4 57.9 015 6 3 10.1 5.5 | 12.1 53.8 215 3 1 7.1 3.9
7250 15.2 59.4 015 6 3 10.0 5.5 | 12.7 54.9 215 3 2 9.4 5.2
7000 15.9 60.6 015 6 3 10.0 5.5 | 13.4 56.1 215 4 2 9.8 5.4
6750 16.7 62.1 015 6 3 9.9 5.5 | 14.1 57.4 210 5 2 7.6 4.1
6500 17.4 63.3 010 6 3 10.6 5.8 | 14.6 58.3 210 5 3 8.8 4.8
6250 18.2 64.8 010 6 3 11.5 6.3 | 15.4 59.7 210 6 3 11.3 6.2
6000 19.1 66.4 010 6 3 10.5 5.8 | 16.2 61.2 210 6 3 10.4 5.7
5750 19.9 67.8 010 6 3 12.3 6.7 | 17.0 62.6 210 6 3 10.5 5.8
5500 21.1 70.0 010 6 3 21.4 11.8 | 17.8 64.0 205 6 3 12.2 6.7
________________________________________________________________________________
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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