Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
516
UXUS97 KBOU 220126
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1925 MDT Saturday, June 21, 2025
This forecast is for Sunday, June 22, 2025:
If the trigger temperature of 82.9 F/28.3 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1031 ft/min (5.2 m/s)
Maximum height of thermals.................. 16884 ft MSL (11604 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 C
Time of trigger temperature.................... 1030 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................. 14606 ft MSL (9326 ft AGL)
Thermal soaring outlook for Monday 06/23....... Fair
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Trending the same
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Neither
Potential height of wave....................... 15859 ft MSL (10579 ft AGL)
Wave soaring outlook for Monday 06/23.......... Poor
Remarks...
Sunrise/Sunset.................... 05:31:59 / 20:31:17 MDT
Total possible sunshine........... 14 hr 59 min 17 sec (899 min 17 sec)
Altitude of sun at 13:01:38 MDT... 73.66 degrees
Upper air data from numerical model forecast valid on 06/22/2025 at 0600 MDT
Freezing level.................. 16184 ft MSL (10904 ft AGL)
Convective condensation level... 23300 ft MSL (18020 ft AGL)
Lifted condensation level....... 21061 ft MSL (15781 ft AGL)
Lifted index.................... +3.7
K index......................... +6.4
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 -64.7 -84.5 230 48 25 3.5 1.9 M M M M M
45000 -58.9 -74.0 235 65 33 4.3 2.3 M M M M M
40000 -52.1 -61.8 230 69 36 6.7 3.7 M M M M M
38000 -48.0 -54.4 230 66 34 6.8 3.7 M M M M M
36000 -44.0 -47.2 225 63 32 6.8 3.7 M M M M M
34000 -39.4 -38.9 225 58 30 7.8 4.3 M M M M M
32000 -34.8 -30.6 220 54 28 7.8 4.3 M M M M M
30000 -29.5 -21.1 220 48 25 7.8 4.3 46.0 114.9 9.3 M M
29000 -27.1 -16.8 220 45 23 7.8 4.3 45.3 113.6 8.8 M M
28000 -24.8 -12.6 220 43 22 7.7 4.2 44.7 112.5 8.5 M M
27000 -22.6 -8.7 215 41 21 7.5 4.1 43.8 110.8 7.8 M M
26000 -20.3 -4.5 215 40 20 7.5 4.1 42.9 109.2 7.2 M M
25000 -18.1 -0.6 210 38 20 7.5 4.1 42.2 107.9 6.7 M M
24000 -15.7 3.7 210 37 19 7.8 4.3 41.4 106.4 6.1 M M
23000 -13.4 7.9 210 36 18 7.8 4.3 40.6 105.1 5.6 M M
22000 -11.1 12.0 210 34 18 7.9 4.3 40.0 104.0 5.1 M M
21000 -8.9 16.0 210 33 17 6.8 3.7 39.0 102.2 4.3 M M
20000 -6.9 19.6 210 32 17 6.8 3.8 38.0 100.3 3.5 M M
19500 -5.9 21.4 210 32 16 6.8 3.7 37.5 99.5 3.1 M M
19000 -4.8 23.4 210 31 16 6.4 3.5 37.0 98.7 2.7 M M
18500 -4.0 24.8 215 32 17 5.9 3.2 36.4 97.4 2.1 M M
18000 -3.1 26.4 215 33 17 5.9 3.2 35.7 96.2 1.5 M M
17500 -2.3 27.9 215 35 18 5.6 3.1 35.0 95.0 0.9 M M
17000 -1.5 29.3 215 37 19 5.7 3.1 34.3 93.7 0.3 M M
16500 -0.6 30.9 220 40 21 5.6 3.1 33.6 92.6 -0.4 1008 5.1
16000 0.1 32.2 220 41 21 5.4 3.0 32.9 91.2 -1.1 970 4.9
15500 0.9 33.6 220 43 22 5.4 3.0 32.2 89.9 -1.8 933 4.7
15000 1.7 35.1 220 42 22 6.9 3.8 31.6 88.8 -2.4 892 4.5
14500 3.1 37.6 220 40 20 7.2 4.0 30.8 87.5 -3.2 828 4.2
14000 4.3 39.7 220 37 19 8.5 4.6 30.6 87.0 -3.6 779 4.0
13500 5.5 41.9 215 34 17 8.4 4.6 30.3 86.6 -3.8 728 3.7
13000 6.8 44.2 215 31 16 9.2 5.0 30.2 86.3 -4.0 675 3.4
12500 8.1 46.6 215 30 15 9.2 5.0 30.1 86.2 -4.2 620 3.1
12000 9.4 48.9 215 28 15 8.6 4.7 30.0 85.9 -4.3 565 2.9
11500 10.7 51.3 220 28 14 8.8 4.8 29.8 85.6 -4.5 512 2.6
11000 12.0 53.6 220 26 13 7.2 4.0 29.5 85.1 -4.8 460 2.3
10500 13.0 55.4 220 24 12 7.9 4.3 29.1 84.4 -5.2 413 2.1
10250 13.7 56.7 220 22 11 11.4 6.2 29.1 84.3 -5.2 384 2.0
10000 14.6 58.3 220 20 10 10.2 5.6 29.2 84.6 -5.1 350 1.8
9750 15.3 59.5 220 19 10 7.6 4.2 29.1 84.4 -5.2 324 1.6
9500 15.9 60.6 220 18 9 8.9 4.9 29.0 84.2 -5.3 298 1.5
9250 16.5 61.7 220 17 9 6.6 3.6 28.9 84.0 -5.4 272 1.4
9000 17.0 62.6 220 16 8 7.0 3.9 28.6 83.4 -5.7 251 1.3
8750 17.6 63.7 225 15 8 9.2 5.0 28.5 83.3 -5.8 224 1.1
8500 18.3 64.9 225 13 7 9.3 5.1 28.4 83.2 -5.9 196 1.0
8250 19.0 66.2 225 12 6 6.5 3.6 28.4 83.1 -5.9 169 0.9
8000 19.3 66.7 230 11 6 5.9 3.3 28.0 82.4 -6.3 150 0.8
7750 20.3 68.5 230 10 5 8.7 4.8 27.9 82.2 -6.4 124 0.6
7500 20.6 69.1 230 10 5 8.9 4.9 27.8 82.0 -6.5 98 0.5
7250 21.2 70.2 230 9 5 6.8 3.7 27.7 81.8 -6.6 71 0.4
7000 21.6 70.9 230 9 5 4.2 2.3 27.3 81.2 -7.0 53 0.3
6750 21.9 71.4 225 10 5 4.1 2.3 26.9 80.4 -7.4 36 0.2
6500 22.2 72.0 225 10 5 2.9 1.6 26.4 79.6 -7.9 20 0.1
6250 22.3 72.1 220 10 5 -2.4 -1.3 25.8 78.4 -8.6 11 0.1
6000 21.9 71.4 215 10 5 -5.1 -2.8 24.7 76.4 -9.7 15 0.1
5750 21.4 70.5 215 11 5 -8.9 -4.9 23.5 74.3 -10.9 21 0.1
5500 20.2 68.4 205 9 5 -22.5 -12.3 21.6 70.9 -12.9 49 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/22/2025 at 0900 MDT | 06/22/2025 at 1200 MDT
|
CAPE... 0.0 LI... +7.3 | CAPE... 0.0 LI... +4.8
CINH... 0.0 K Index... -8.7 | CINH... -0.9 K Index... +7.4
|
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 -64.1 -83.4 225 44 23 4.5 2.4 | -64.2 -83.6 205 41 21 2.5 1.4
45000 -57.4 -71.3 230 63 32 3.8 2.1 | -58.9 -74.0 215 58 30 5.7 3.1
40000 -51.4 -60.5 230 76 39 6.0 3.3 | -50.2 -58.4 220 73 37 6.3 3.4
38000 -47.8 -54.0 225 70 36 6.0 3.3 | -46.5 -51.7 220 72 37 6.3 3.4
36000 -44.2 -47.6 220 66 34 6.0 3.3 | -42.7 -44.9 220 72 37 6.3 3.4
34000 -39.9 -39.8 215 60 31 7.6 4.2 | -38.8 -37.8 215 68 35 6.6 3.6
32000 -34.8 -30.6 215 54 28 7.5 4.1 | -34.4 -29.9 210 63 33 6.5 3.6
30000 -29.9 -21.8 215 49 25 8.3 4.6 | -29.7 -21.5 210 60 31 8.1 4.4
29000 -27.4 -17.3 210 47 24 8.3 4.6 | -27.3 -17.1 205 58 30 8.1 4.4
28000 -24.9 -12.8 210 45 23 8.0 4.4 | -24.8 -12.6 205 56 29 8.0 4.4
27000 -22.6 -8.7 210 45 23 7.5 4.1 | -22.5 -8.5 205 55 28 7.9 4.3
26000 -20.4 -4.7 205 44 23 7.5 4.1 | -20.1 -4.2 205 54 28 7.9 4.3
25000 -18.2 -0.8 205 44 23 7.5 4.1 | -17.8 -0.0 205 54 28 7.9 4.3
24000 -15.9 3.4 205 43 22 7.5 4.1 | -15.5 4.1 205 53 27 7.1 3.9
23000 -13.7 7.3 205 43 22 7.5 4.1 | -13.4 7.9 210 52 27 7.1 3.9
22000 -11.4 11.5 205 42 22 7.5 4.1 | -11.3 11.7 210 52 27 7.2 3.9
21000 -9.3 15.3 210 41 21 7.0 3.9 | -9.5 14.9 215 51 26 5.6 3.1
20000 -7.2 19.0 210 40 21 7.0 3.9 | -7.8 18.0 220 49 25 5.6 3.1
19500 -6.1 21.0 210 39 20 7.0 3.8 | -7.0 19.4 220 48 25 5.7 3.1
19000 -5.1 22.8 210 39 20 6.8 3.7 | -6.2 20.8 220 47 24 5.5 3.0
18500 -4.1 24.6 210 39 20 6.5 3.6 | -5.4 22.3 225 45 23 5.2 2.8
18000 -3.1 26.4 215 39 20 6.5 3.6 | -4.7 23.5 225 43 22 5.2 2.8
17500 -2.2 28.0 215 40 20 6.3 3.5 | -3.9 25.0 225 40 21 5.9 3.2
17000 -0.8 30.6 220 41 21 6.3 3.5 | -2.6 27.3 225 37 19 5.8 3.2
16500 0.1 32.2 220 41 21 5.8 3.2 | -1.7 28.9 225 35 18 6.9 3.8
16000 1.0 33.8 225 40 21 5.7 3.2 | -0.7 30.7 225 33 17 6.9 3.8
15500 1.8 35.2 225 39 20 5.5 3.0 | 0.3 32.5 225 31 16 7.2 3.9
15000 2.6 36.7 225 36 19 5.2 2.8 | 1.4 34.5 230 30 15 7.3 4.0
14500 3.3 37.9 225 33 17 5.3 2.9 | 2.5 36.5 230 28 15 7.3 4.0
14000 4.1 39.4 230 31 16 5.8 3.2 | 3.5 38.3 230 26 14 7.1 3.9
13500 4.9 40.8 230 28 15 5.7 3.1 | 4.6 40.3 230 24 12 7.1 3.9
13000 5.8 42.4 230 26 13 6.6 3.6 | 5.7 42.3 230 22 11 8.3 4.6
12500 6.7 44.1 235 24 13 6.5 3.6 | 6.9 44.4 230 20 10 8.1 4.5
12000 7.7 45.9 235 23 12 7.4 4.1 | 8.1 46.6 225 18 9 9.2 5.1
11500 8.8 47.8 235 21 11 7.5 4.1 | 9.5 49.1 225 17 9 9.3 5.1
11000 9.9 49.8 235 19 10 7.1 3.9 | 10.8 51.4 220 16 8 8.2 4.5
10500 10.9 51.6 235 17 9 7.3 4.0 | 12.0 53.6 220 15 8 9.3 5.1
10250 11.5 52.7 235 16 8 11.1 6.1 | 12.8 55.0 220 15 8 12.8 7.0
10000 12.4 54.3 235 16 8 11.0 6.0 | 13.8 56.8 220 15 8 11.2 6.2
9750 13.1 55.6 230 16 8 8.5 4.7 | 14.5 58.1 220 14 7 9.1 5.0
9500 13.8 56.8 230 15 8 9.6 5.3 | 15.2 59.4 220 14 7 10.0 5.5
9250 14.4 57.9 230 15 7 7.6 4.1 | 15.9 60.6 220 14 7 8.5 4.6
9000 14.9 58.8 225 13 7 7.8 4.3 | 16.5 61.7 220 14 7 9.1 5.0
8750 15.6 60.1 225 13 7 9.6 5.3 | 17.3 63.1 215 14 7 10.7 5.9
8500 16.3 61.3 220 13 7 9.5 5.2 | 18.1 64.6 215 14 7 10.8 5.9
8250 17.0 62.6 220 13 7 8.1 4.4 | 18.9 66.0 215 13 7 8.8 4.8
8000 17.5 63.5 215 12 6 7.5 4.1 | 19.5 67.1 215 13 7 9.1 5.0
7750 18.2 64.8 215 12 6 8.7 4.8 | 20.3 68.5 215 13 7 11.1 6.1
7500 18.8 65.8 215 12 6 9.0 5.0 | 21.1 70.0 215 13 7 11.2 6.1
7250 19.4 66.9 215 12 6 7.3 4.0 | 21.9 71.4 215 12 6 8.6 4.7
7000 19.9 67.8 210 11 6 6.5 3.6 | 22.4 72.3 215 13 6 7.5 4.1
6750 20.5 68.9 210 11 6 9.9 5.4 | 23.1 73.6 215 12 6 11.5 6.3
6500 21.3 70.3 210 11 6 10.9 6.0 | 24.0 75.2 215 12 6 12.3 6.8
6250 22.1 71.8 210 10 5 9.6 5.3 | 24.9 76.8 215 11 6 10.5 5.7
6000 22.8 73.0 205 10 5 9.3 5.1 | 25.6 78.1 215 11 6 10.0 5.5
5750 23.5 74.3 205 10 5 9.8 5.4 | 26.4 79.5 215 11 6 10.3 5.7
5500 24.3 75.7 210 8 4 14.3 7.9 | 27.3 81.1 210 9 5 17.9 9.8
06/22/2025 at 1500 MDT | 06/22/2025 at 1800 MDT
|
CAPE... +4.2 LI... +1.5 | CAPE... +5.3 LI... +0.1
CINH... -0.4 K Index... +13.4 | CINH... -6.2 K Index... +14.8
|
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 -63.6 -82.5 210 49 25 1.8 1.0 | -63.6 -82.5 215 51 26 2.8 1.5
45000 -59.1 -74.4 215 59 31 5.3 2.9 | -58.7 -73.7 220 61 31 4.5 2.5
40000 -50.9 -59.6 210 70 36 7.2 3.9 | -51.5 -60.7 215 69 36 7.2 4.0
38000 -46.5 -51.7 210 71 37 7.2 4.0 | -47.1 -52.8 215 71 36 7.3 4.0
36000 -42.2 -44.0 210 72 37 7.2 4.0 | -42.7 -44.9 215 72 37 7.3 4.0
34000 -38.1 -36.6 210 71 36 6.8 3.7 | -38.5 -37.3 215 71 37 7.0 3.8
32000 -34.0 -29.2 210 68 35 6.8 3.7 | -34.3 -29.7 215 69 36 7.0 3.8
30000 -28.8 -19.8 210 65 33 8.1 4.4 | -29.4 -20.9 220 67 34 7.5 4.1
29000 -26.4 -15.5 210 63 33 8.1 4.4 | -27.1 -16.8 220 65 34 7.5 4.1
28000 -23.9 -11.0 210 62 32 7.6 4.2 | -24.9 -12.8 220 64 33 6.9 3.8
27000 -21.8 -7.2 210 62 32 7.0 3.9 | -23.0 -9.4 225 62 32 6.2 3.4
26000 -19.7 -3.5 215 63 33 7.0 3.9 | -21.2 -6.2 225 59 30 6.2 3.4
25000 -17.6 0.3 215 65 33 7.3 4.0 | -19.3 -2.7 225 57 29 6.2 3.4
24000 -16.2 2.8 220 61 31 3.9 2.1 | -17.5 0.5 230 52 27 5.9 3.2
23000 -15.0 5.0 220 55 28 4.0 2.2 | -15.8 3.6 230 48 24 5.9 3.3
22000 -13.9 7.0 225 49 25 4.0 2.2 | -14.1 6.6 230 43 22 6.0 3.3
21000 -12.0 10.4 225 46 24 7.4 4.0 | -12.2 10.0 230 37 19 6.5 3.6
20000 -9.8 14.4 230 44 22 7.4 4.0 | -10.3 13.5 230 32 16 6.5 3.6
19500 -8.7 16.3 230 42 22 7.3 4.0 | -9.4 15.1 230 29 15 6.5 3.6
19000 -7.6 18.3 230 41 21 7.1 3.9 | -8.4 16.9 235 26 14 8.1 4.4
18500 -6.6 20.1 230 39 20 6.9 3.8 | -7.1 19.2 230 24 13 8.7 4.8
18000 -5.6 21.9 235 37 19 6.8 3.8 | -5.8 21.6 230 22 11 8.8 4.8
17500 -4.6 23.7 235 35 18 7.5 4.1 | -4.5 23.9 230 21 11 9.5 5.2
17000 -3.5 25.7 235 32 17 7.5 4.1 | -3.1 26.4 230 20 10 9.4 5.2
16500 -2.4 27.7 235 29 15 8.2 4.5 | -1.7 28.9 225 19 10 9.5 5.2
16000 -1.1 30.0 230 27 14 8.7 4.8 | -0.2 31.6 225 18 9 9.5 5.2
15500 0.2 32.4 230 25 13 8.8 4.8 | 1.2 34.2 225 18 9 9.5 5.2
15000 1.6 34.9 230 24 12 9.2 5.1 | 2.6 36.7 225 17 9 9.4 5.2
14500 2.9 37.2 225 22 12 9.2 5.0 | 4.0 39.2 220 17 9 9.4 5.2
14000 4.3 39.7 225 21 11 9.7 5.3 | 5.4 41.7 220 16 8 9.4 5.1
13500 6.5 43.7 225 20 10 9.6 5.3 | 7.5 45.5 220 15 8 9.4 5.2
13000 7.9 46.2 220 19 10 9.4 5.2 | 9.0 48.2 225 15 8 9.6 5.3
12500 9.3 48.7 220 18 9 9.4 5.2 | 10.4 50.7 225 14 7 9.6 5.3
12000 10.8 51.4 225 18 9 9.8 5.4 | 11.8 53.2 225 14 7 9.5 5.2
11500 12.2 54.0 225 17 9 10.0 5.5 | 13.3 55.9 230 13 7 9.7 5.3
11000 13.6 56.5 225 17 9 8.1 4.4 | 14.5 58.1 230 13 7 7.6 4.2
10500 14.8 58.6 225 16 8 11.2 6.1 | 15.7 60.3 235 12 6 11.7 6.4
10250 15.8 60.4 225 16 8 13.4 7.4 | 16.8 62.2 240 12 6 13.4 7.4
10000 16.6 61.9 225 16 8 10.0 5.5 | 17.5 63.5 240 12 6 9.0 4.9
9750 17.4 63.3 225 16 8 9.5 5.2 | 18.2 64.8 245 12 6 9.5 5.2
9500 18.1 64.6 225 15 8 10.3 5.7 | 18.9 66.0 245 12 6 10.1 5.5
9250 18.8 65.8 225 15 8 7.5 4.1 | 19.6 67.3 250 12 6 7.1 3.9
9000 19.3 66.7 225 15 8 8.3 4.6 | 20.1 68.2 250 11 6 8.2 4.5
8750 20.1 68.2 225 15 7 11.4 6.2 | 20.9 69.6 250 12 6 11.8 6.5
8500 20.9 69.6 225 14 7 11.5 6.3 | 21.8 71.2 255 12 6 11.7 6.4
8250 21.8 71.2 225 14 7 7.8 4.3 | 22.6 72.7 255 12 6 7.0 3.9
8000 22.2 72.0 225 14 7 8.1 4.5 | 22.9 73.2 255 12 6 7.5 4.1
7750 23.1 73.6 225 13 7 12.3 6.7 | 23.8 74.8 260 12 6 12.5 6.9
7500 23.9 75.0 225 13 7 11.3 6.2 | 24.7 76.5 260 12 6 11.0 6.1
7250 24.7 76.5 225 13 7 8.5 4.7 | 25.4 77.7 260 12 6 8.4 4.6
7000 25.3 77.5 225 13 7 7.8 4.3 | 26.0 78.8 260 12 6 7.8 4.3
6750 26.0 78.8 225 12 6 11.9 6.5 | 26.7 80.1 265 11 6 11.8 6.5
6500 26.9 80.4 225 12 6 12.0 6.6 | 27.6 81.7 265 11 6 11.6 6.4
6250 27.7 81.9 225 11 6 9.6 5.3 | 28.4 83.1 265 11 6 9.2 5.1
6000 28.4 83.1 225 11 6 9.0 4.9 | 29.0 84.2 270 11 5 8.5 4.7
5750 29.2 84.6 225 10 5 12.2 6.7 | 29.8 85.6 270 10 5 11.8 6.5
5500 30.4 86.7 225 9 5 21.3 11.7 | 30.8 87.4 275 8 4 17.0 9.3
________________________________________________________________________________
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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