Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
185
UXUS97 KBOU 180023
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1822 MDT Monday, June 17, 2024
This forecast is for Tuesday, June 18, 2024:
If the trigger temperature of 70.2 F/21.2 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 306 ft/min (1.6 m/s)
Maximum height of thermals.................. 10438 ft MSL (5137 ft AGL)
Forecast maximum temperature................... 77.0 F/25.5 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................. 9478 ft MSL (4177 ft AGL)
Thermal soaring outlook for Wednesday 06/19.... Poor
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....................... 46298 ft MSL (40997 ft AGL)
Wave soaring outlook for Wednesday 06/19....... Poor
Remarks...
Sunrise/Sunset.................... 05:31:11 / 20:30:26 MDT
Total possible sunshine........... 14 hr 59 min 15 sec (899 min 15 sec)
Altitude of sun at 13:00:49 MDT... 73.65 degrees
Upper air data from numerical model forecast valid on 06/18/2024 at 0600 MDT
Freezing level.................. 14708 ft MSL (9407 ft AGL)
Convective condensation level... 16316 ft MSL (11015 ft AGL)
Lifted condensation level....... 14687 ft MSL (9386 ft AGL)
Lifted index.................... +2.3
K index......................... +16.1
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 -58.8 -73.8 230 56 29 3.7 2.0 M M M M M
45000 -54.4 -65.9 225 67 35 -0.1 -0.1 M M M M M
40000 -54.3 -65.7 220 62 32 5.6 3.1 M M M M M
38000 -50.3 -58.5 220 61 31 6.7 3.7 M M M M M
36000 -46.3 -51.3 215 60 31 6.7 3.6 M M M M M
34000 -42.0 -43.6 215 59 31 7.6 4.2 M M M M M
32000 -37.4 -35.3 210 60 31 7.6 4.2 M M M M M
30000 -32.6 -26.7 210 59 30 8.2 4.5 44.0 111.2 14.4 M M
29000 -30.2 -22.4 215 59 30 8.2 4.5 43.4 110.1 14.1 M M
28000 -27.2 -17.0 215 58 30 8.4 4.6 42.8 109.0 13.8 M M
27000 -25.0 -13.0 215 57 29 6.9 3.8 41.8 107.2 13.1 M M
26000 -22.9 -9.2 220 56 29 6.9 3.8 40.7 105.2 12.4 M M
25000 -20.9 -5.6 225 55 28 6.9 3.8 39.7 103.5 11.7 M M
24000 -18.9 -2.0 225 53 28 6.4 3.5 38.6 101.5 10.9 M M
23000 -17.0 1.4 225 52 27 6.4 3.5 37.3 99.2 10.0 M M
22000 -15.1 4.8 225 50 26 6.5 3.5 36.2 97.1 9.1 M M
21000 -13.1 8.4 225 49 25 7.3 4.0 35.2 95.3 8.3 M M
20000 -10.9 12.4 225 47 24 7.3 4.0 34.3 93.7 7.7 M M
19500 -9.8 14.4 225 46 23 7.3 4.0 33.9 93.0 7.4 M M
19000 -8.7 16.3 225 45 23 7.4 4.1 33.5 92.3 7.1 M M
18500 -7.7 18.1 220 43 22 5.8 3.2 33.0 91.3 6.7 M M
18000 -6.8 19.8 220 42 22 6.0 3.3 32.3 90.2 6.2 M M
17500 -5.9 21.4 220 41 21 5.9 3.2 31.7 89.1 5.7 M M
17000 -5.1 22.8 220 39 20 5.9 3.2 31.0 87.8 5.0 M M
16500 -4.2 24.4 215 37 19 5.9 3.3 30.4 86.7 4.4 M M
16000 -3.3 26.1 215 35 18 7.5 4.1 29.9 85.7 3.9 M M
15500 -2.3 27.9 220 32 16 7.3 4.0 29.5 85.0 3.5 M M
15000 -1.2 29.8 220 30 15 8.9 4.9 29.1 84.5 3.2 M M
14500 0.9 33.6 225 28 15 9.3 5.1 29.0 84.2 3.1 M M
14000 2.2 36.0 230 27 14 8.2 4.5 28.9 83.9 3.0 M M
13500 3.4 38.1 230 26 13 8.3 4.5 28.6 83.5 2.7 M M
13000 4.7 40.5 230 25 13 8.8 4.9 28.4 83.1 2.6 M M
12500 6.0 42.8 230 23 12 9.0 4.9 28.3 82.9 2.4 M M
12000 7.3 45.1 225 22 11 7.2 3.9 28.1 82.6 2.3 M M
11500 8.2 46.8 220 20 10 6.1 3.4 27.5 81.6 1.8 M M
11000 9.1 48.4 215 18 9 4.0 2.2 27.0 80.5 1.2 M M
10500 9.4 48.9 205 14 7 2.4 1.3 25.7 78.3 0.0 M M
10250 9.5 49.1 200 12 6 1.6 0.9 25.2 77.3 -0.5 296 1.5
10000 9.6 49.3 185 9 5 -0.5 -0.3 24.4 76.0 -1.3 288 1.5
9750 9.4 48.9 175 8 4 -1.2 -0.7 23.6 74.4 -2.1 285 1.4
9500 9.3 48.7 165 7 4 -1.3 -0.7 22.7 72.9 -3.0 281 1.4
9250 9.2 48.6 150 6 3 0.0 0.0 21.9 71.4 -3.9 278 1.4
9000 9.2 48.6 140 6 3 0.6 0.4 21.2 70.2 -4.6 270 1.4
8750 9.2 48.6 125 4 2 -0.2 -0.1 20.4 68.8 -5.3 262 1.3
8500 9.2 48.6 095 3 2 -0.0 -0.0 19.7 67.4 -6.1 255 1.3
8250 9.2 48.6 060 3 2 0.0 0.0 18.9 66.1 -6.8 247 1.3
8000 9.2 48.6 035 5 3 0.5 0.3 18.2 64.8 -7.5 239 1.2
7750 9.3 48.7 035 8 4 1.1 0.6 17.5 63.5 -8.2 230 1.2
7500 9.3 48.7 035 10 5 0.4 0.2 16.8 62.3 -8.9 221 1.1
7250 9.4 48.9 035 12 6 2.8 1.6 16.2 61.1 -9.6 212 1.1
7000 9.8 49.6 040 14 7 6.4 3.5 15.8 60.5 -10.0 194 1.0
6750 10.2 50.4 045 15 8 7.0 3.8 15.6 60.1 -10.2 172 0.9
6500 10.8 51.4 045 15 8 7.2 4.0 15.4 59.7 -10.5 149 0.8
6250 11.3 52.3 050 15 8 7.8 4.3 15.2 59.4 -10.7 126 0.6
6000 11.9 53.4 055 14 7 8.1 4.4 15.1 59.2 -10.9 101 0.5
5750 12.5 54.5 065 12 6 8.8 4.8 15.0 59.0 -11.0 76 0.4
5500 13.1 55.6 075 10 5 9.2 5.0 14.9 58.9 -11.1 48 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/18/2024 at 0900 MDT | 06/18/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.6 | CAPE... 0.0 LI... +1.6
CINH... 0.0 K Index... +19.2 | CINH... 0.0 K Index... +19.1
|
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 -57.7 -71.9 220 57 29 3.4 1.8 | -57.5 -71.5 215 57 30 1.7 0.9
45000 -53.8 -64.8 220 71 36 -0.6 -0.3 | -55.2 -67.4 225 78 40 0.8 0.4
40000 -54.6 -66.3 220 73 38 4.5 2.5 | -53.8 -64.8 220 78 40 4.1 2.2
38000 -50.8 -59.4 215 71 36 6.3 3.4 | -50.5 -58.9 220 77 40 5.6 3.0
36000 -47.1 -52.8 215 68 35 6.3 3.4 | -47.2 -53.0 220 76 39 5.5 3.0
34000 -42.7 -44.9 215 67 34 7.8 4.3 | -43.1 -45.6 220 74 38 7.5 4.1
32000 -38.0 -36.4 215 66 34 7.8 4.3 | -38.6 -37.5 220 72 37 7.5 4.1
30000 -33.3 -27.9 220 65 34 8.1 4.4 | -34.0 -29.2 225 69 36 7.8 4.3
29000 -30.9 -23.6 220 65 33 8.1 4.5 | -31.7 -25.1 225 68 35 7.8 4.3
28000 -28.5 -19.3 220 65 33 8.1 4.4 | -29.4 -20.9 225 67 34 7.8 4.3
27000 -25.7 -14.3 220 63 32 7.1 3.9 | -26.6 -15.9 230 65 33 7.2 4.0
26000 -23.6 -10.5 220 60 31 7.1 3.9 | -24.4 -11.9 230 64 33 7.2 4.0
25000 -21.5 -6.7 220 58 30 7.1 3.9 | -22.2 -8.0 230 63 32 7.2 4.0
24000 -19.5 -3.1 220 55 28 6.0 3.3 | -20.0 -4.0 230 62 32 7.6 4.2
23000 -17.7 0.1 220 53 27 6.0 3.3 | -17.8 -0.0 230 61 31 7.6 4.2
22000 -16.0 3.2 220 50 26 6.1 3.3 | -15.5 4.1 230 59 31 7.6 4.2
21000 -14.0 6.8 225 48 25 7.3 4.0 | -13.5 7.7 230 57 29 6.2 3.4
20000 -11.8 10.8 225 46 24 7.3 4.0 | -11.7 10.9 235 54 28 6.1 3.4
19500 -10.7 12.7 225 45 23 7.3 4.0 | -10.8 12.6 235 52 27 6.1 3.4
19000 -9.6 14.7 225 44 23 7.3 4.0 | -9.9 14.2 235 51 26 6.1 3.3
18500 -8.5 16.7 225 43 22 6.8 3.7 | -9.2 15.4 235 49 25 4.2 2.3
18000 -7.5 18.5 225 41 21 6.8 3.7 | -8.6 16.5 235 47 24 4.6 2.5
17500 -6.5 20.3 220 40 20 6.5 3.6 | -7.9 17.8 235 45 23 6.8 3.8
17000 -5.6 21.9 220 38 20 6.3 3.5 | -6.8 19.8 235 43 22 7.8 4.3
16500 -4.7 23.5 215 36 19 6.4 3.5 | -5.7 21.7 235 41 21 7.9 4.3
16000 -3.7 25.3 210 35 18 7.4 4.0 | -4.5 23.9 230 38 20 7.6 4.2
15500 -2.7 27.1 210 33 17 7.4 4.0 | -3.4 25.9 230 36 19 7.6 4.2
15000 -1.6 29.1 205 32 16 8.6 4.7 | -2.3 27.9 225 34 18 8.2 4.5
14500 -0.4 31.3 210 31 16 8.7 4.8 | -1.1 30.0 220 32 17 8.3 4.5
14000 0.9 33.6 215 29 15 9.0 4.9 | 0.0 32.0 215 31 16 9.0 4.9
13500 2.4 36.3 220 30 15 9.2 5.1 | 2.2 36.0 215 30 16 9.6 5.2
13000 4.4 39.9 230 30 15 8.2 4.5 | 3.5 38.3 220 30 15 8.0 4.4
12500 5.6 42.1 235 29 15 8.2 4.5 | 4.7 40.5 220 28 14 8.1 4.4
12000 6.8 44.2 235 27 14 8.1 4.5 | 5.8 42.4 220 26 13 8.0 4.4
11500 8.0 46.4 230 25 13 8.2 4.5 | 7.0 44.6 220 23 12 8.2 4.5
11000 9.1 48.4 225 23 12 5.1 2.8 | 8.1 46.6 220 19 10 4.5 2.5
10500 9.7 49.5 220 20 10 3.9 2.2 | 8.5 47.3 215 16 8 3.9 2.2
10250 9.9 49.8 215 19 10 3.5 1.9 | 8.8 47.8 210 15 8 0.6 0.3
10000 10.1 50.2 210 17 9 0.5 0.3 | 8.6 47.5 200 12 6 -3.6 -2.0
9750 9.9 49.8 205 15 8 -1.5 -0.8 | 8.3 46.9 180 9 5 -3.1 -1.7
9500 9.8 49.6 195 14 7 -0.7 -0.4 | 8.0 46.4 155 8 4 -4.1 -2.2
9250 9.7 49.5 185 13 7 -1.7 -0.9 | 7.7 45.9 130 9 5 -0.4 -0.2
9000 9.4 48.9 185 13 7 -4.1 -2.3 | 7.9 46.2 120 10 5 6.7 3.7
8750 9.1 48.4 185 13 6 -4.9 -2.7 | 8.5 47.3 115 10 5 8.3 4.5
8500 8.7 47.7 185 12 6 -4.9 -2.7 | 9.1 48.4 110 11 6 7.6 4.2
8250 8.4 47.1 190 11 6 -4.2 -2.3 | 9.7 49.5 105 12 6 8.8 4.8
8000 8.2 46.8 180 9 5 -0.6 -0.3 | 10.4 50.7 100 12 6 10.1 5.6
7750 8.3 46.9 160 8 4 3.8 2.1 | 11.2 52.2 100 12 6 9.9 5.4
7500 8.6 47.5 145 7 4 4.2 2.3 | 11.9 53.4 100 12 6 9.6 5.3
7250 8.9 48.0 125 7 4 6.8 3.7 | 12.6 54.7 100 12 6 10.7 5.9
7000 9.6 49.3 125 7 4 9.8 5.4 | 13.5 56.3 100 12 6 11.5 6.3
6750 10.3 50.5 125 7 4 9.8 5.4 | 14.3 57.7 100 12 6 10.0 5.5
6500 11.1 52.0 125 7 4 10.7 5.9 | 15.0 59.0 100 12 6 9.8 5.4
6250 11.9 53.4 125 7 4 10.7 5.9 | 15.8 60.4 100 12 6 10.8 5.9
6000 12.7 54.9 120 7 4 11.1 6.1 | 16.6 61.9 100 11 6 11.5 6.3
5750 13.5 56.3 120 7 4 10.6 5.8 | 17.5 63.5 100 11 6 10.5 5.8
5500 14.4 57.9 120 7 3 15.7 8.6 | 18.4 65.1 095 11 6 18.5 10.2
06/18/2024 at 1500 MDT | 06/18/2024 at 1800 MDT
|
CAPE... 0.0 LI... +0.4 | CAPE... 0.0 LI... +3.8
CINH... 0.0 K Index... +23.8 | CINH... 0.0 K Index... +24.3
|
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 -59.0 -74.2 215 59 30 2.4 1.3 | -58.5 -73.3 215 58 30 1.8 1.0
45000 -55.6 -68.1 225 74 38 1.8 1.0 | -56.0 -68.8 225 72 37 1.2 0.7
40000 -52.7 -62.9 230 72 37 4.3 2.4 | -53.9 -65.0 230 74 38 4.9 2.7
38000 -49.6 -57.3 230 70 36 5.2 2.8 | -50.3 -58.5 235 74 38 6.0 3.3
36000 -46.5 -51.7 230 68 35 5.1 2.8 | -46.7 -52.1 235 74 38 6.0 3.3
34000 -42.7 -44.9 230 68 35 7.1 3.9 | -42.7 -44.9 235 72 37 7.1 3.9
32000 -38.5 -37.3 230 68 35 7.1 3.9 | -38.5 -37.3 235 67 35 7.1 3.9
30000 -34.2 -29.6 230 69 35 7.4 4.0 | -34.3 -29.7 240 65 34 6.9 3.8
29000 -32.0 -25.6 235 69 36 7.4 4.0 | -32.2 -26.0 240 65 33 6.9 3.8
28000 -29.8 -21.6 235 69 36 7.4 4.0 | -29.6 -21.3 240 64 33 6.9 3.8
27000 -27.0 -16.6 235 68 35 7.5 4.1 | -27.5 -17.5 240 64 33 7.1 3.9
26000 -24.7 -12.5 235 65 34 7.5 4.1 | -25.4 -13.7 240 64 33 7.2 3.9
25000 -22.5 -8.5 230 63 32 7.5 4.1 | -23.3 -9.9 240 64 33 7.2 3.9
24000 -20.4 -4.7 235 61 31 6.4 3.5 | -21.1 -6.0 235 62 32 7.5 4.1
23000 -18.5 -1.3 235 59 30 6.4 3.5 | -18.9 -2.0 235 59 31 7.6 4.2
22000 -16.6 2.1 240 58 30 6.5 3.5 | -16.7 1.9 235 57 29 7.6 4.2
21000 -14.7 5.5 245 55 28 6.6 3.6 | -14.4 6.1 235 52 27 7.9 4.3
20000 -12.8 9.0 240 50 26 6.7 3.7 | -12.1 10.2 230 47 24 8.0 4.4
19500 -11.9 10.6 240 48 25 6.8 3.7 | -11.0 12.2 230 44 23 8.0 4.4
19000 -10.9 12.4 240 46 23 7.1 3.9 | -9.8 14.4 230 41 21 8.1 4.4
18500 -9.8 14.4 240 44 23 8.5 4.6 | -8.6 16.5 230 40 20 8.2 4.5
18000 -8.6 16.5 240 42 22 8.4 4.6 | -7.5 18.5 230 38 20 8.3 4.5
17500 -7.4 18.7 235 41 21 8.3 4.6 | -6.3 20.7 225 37 19 7.2 3.9
17000 -6.2 20.8 235 39 20 8.3 4.5 | -5.3 22.5 225 36 19 7.0 3.8
16500 -5.0 23.0 235 37 19 8.1 4.4 | -4.3 24.3 225 35 18 6.7 3.7
16000 -3.9 25.0 230 36 18 7.3 4.0 | -3.5 25.7 225 33 17 5.8 3.2
15500 -2.8 27.0 230 34 18 7.5 4.1 | -2.7 27.1 220 32 16 6.0 3.3
15000 -1.8 28.8 230 33 17 6.7 3.7 | -1.6 29.1 215 29 15 4.8 2.6
14500 -0.8 30.6 225 31 16 6.7 3.7 | -0.9 30.4 210 28 14 4.9 2.7
14000 0.5 32.9 220 27 14 5.5 3.0 | -0.2 31.6 205 25 13 5.5 3.0
13500 1.2 34.2 215 24 13 6.0 3.3 | 0.6 33.1 200 22 12 6.0 3.3
13000 1.8 35.2 210 22 11 2.8 1.6 | 1.0 33.8 195 19 10 -0.2 -0.1
12500 2.2 36.0 200 18 9 3.1 1.7 | 1.1 34.0 185 14 7 -0.2 -0.1
12000 2.7 36.9 190 15 8 3.1 1.7 | 1.7 35.1 170 10 5 6.9 3.8
11500 3.2 37.8 170 11 5 2.8 1.6 | 2.8 37.0 140 8 4 6.8 3.7
11000 3.9 39.0 140 9 5 6.8 3.7 | 3.9 39.0 115 9 4 8.0 4.4
10500 5.1 41.2 120 10 5 6.1 3.4 | 5.1 41.2 100 9 5 7.0 3.8
10250 5.6 42.1 110 10 5 11.9 6.5 | 5.7 42.3 095 10 5 12.4 6.8
10000 6.8 44.2 105 11 5 13.4 7.3 | 6.9 44.4 095 10 5 13.2 7.2
9750 7.5 45.5 100 11 6 8.7 4.8 | 7.6 45.7 090 10 5 8.3 4.6
9500 8.2 46.8 100 11 6 10.2 5.6 | 8.3 46.9 090 10 5 9.6 5.3
9250 8.9 48.0 100 11 6 9.0 4.9 | 9.0 48.2 090 10 5 9.3 5.1
9000 9.6 49.3 100 11 6 9.3 5.1 | 9.7 49.5 090 10 5 9.8 5.4
8750 10.4 50.7 095 11 6 10.5 5.7 | 10.4 50.7 085 10 5 10.2 5.6
8500 11.1 52.0 095 11 6 10.0 5.5 | 11.2 52.2 085 10 5 10.0 5.5
8250 11.9 53.4 095 11 6 10.9 6.0 | 11.9 53.4 085 10 5 10.3 5.6
8000 12.7 54.9 095 11 6 10.7 5.8 | 12.7 54.9 080 10 5 10.0 5.5
7750 13.4 56.1 095 11 6 9.3 5.1 | 13.4 56.1 080 10 5 9.4 5.2
7500 14.1 57.4 090 11 6 9.3 5.1 | 14.1 57.4 080 10 5 9.4 5.2
7250 14.8 58.6 090 11 6 10.1 5.5 | 14.8 58.6 080 10 5 9.7 5.3
7000 15.6 60.1 090 11 6 10.5 5.8 | 15.6 60.1 075 10 5 9.9 5.4
6750 16.4 61.5 090 11 6 10.3 5.6 | 16.3 61.3 075 10 5 8.9 4.9
6500 17.2 63.0 090 11 6 10.6 5.8 | 16.9 62.4 075 10 5 9.6 5.2
6250 18.0 64.4 090 11 6 11.3 6.2 | 17.7 63.9 070 10 5 10.9 6.0
6000 18.8 65.8 090 11 6 11.1 6.1 | 18.5 65.3 070 10 5 10.7 5.9
5750 19.7 67.5 085 11 5 11.8 6.5 | 19.3 66.7 070 9 5 10.9 6.0
5500 20.8 69.4 085 10 5 21.2 11.6 | 20.2 68.4 065 9 5 13.3 7.3
________________________________________________________________________________
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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