Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
169
UXUS97 KBOU 191317
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0716 MDT Saturday, October 19, 2024
This forecast is for Saturday, October 19, 2024:
If the trigger temperature of 60.0 F/15.6 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 9108 ft MSL (3791 ft AGL)
Forecast maximum temperature................... 59.0 F/15.5 C
Time of trigger temperature.................... 1415 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................. 8172 ft MSL (2855 ft AGL)
Thermal soaring outlook for Sunday 10/20....... Poor
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....................... 35052 ft MSL (29735 ft AGL)
Wave soaring outlook for Sunday 10/20.......... Poor
Remarks...
Sunrise/Sunset.................... 07:14:50 / 18:13:43 MDT
Total possible sunshine........... 10 hr 58 min 53 sec (658 min 53 sec)
Altitude of sun at 12:44:16 MDT... 39.74 degrees
Upper air data from numerical model forecast valid on 10/19/2024 at 0600 MDT
Freezing level.................. 12888 ft MSL (7571 ft AGL)
Convective condensation level... 14628 ft MSL (9311 ft AGL)
Lifted condensation level....... 10883 ft MSL (5566 ft AGL)
Lifted index.................... +4.2
K index......................... +15.5
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 -60.4 -76.7 240 25 13 1.7 0.9 M M M M M
45000 -57.5 -71.5 225 33 17 2.6 1.4 M M M M M
40000 -53.6 -64.5 230 20 10 2.9 1.6 M M M M M
38000 -53.3 -63.9 210 30 15 0.1 0.1 M M M M M
36000 -53.2 -63.8 200 44 23 0.1 0.1 M M M M M
34000 -50.6 -59.1 195 49 25 9.0 5.0 M M M M M
32000 -45.2 -49.4 200 44 23 9.1 5.0 M M M M M
30000 -39.4 -38.9 200 36 19 8.2 4.5 36.2 97.2 16.0 M M
29000 -36.9 -34.4 200 32 17 8.2 4.5 35.6 96.1 15.7 M M
28000 -34.5 -30.1 205 28 15 8.3 4.5 35.1 95.3 15.5 M M
27000 -32.1 -25.8 205 25 13 7.9 4.3 34.4 94.0 15.2 M M
26000 -29.7 -21.5 210 21 11 7.9 4.3 33.7 92.6 14.7 M M
25000 -27.4 -17.3 215 18 9 7.9 4.3 33.0 91.5 14.4 M M
24000 -25.1 -13.2 220 16 8 7.5 4.1 32.3 90.1 13.9 M M
23000 -22.9 -9.2 220 14 7 7.5 4.1 31.4 88.5 13.3 M M
22000 -20.7 -5.3 225 12 6 7.5 4.1 30.6 87.2 12.8 M M
21000 -18.4 -1.1 225 11 6 8.0 4.4 29.9 85.9 12.4 M M
20000 -16.0 3.2 225 11 6 8.0 4.4 29.3 84.7 12.0 M M
19500 -14.8 5.4 225 10 5 8.0 4.4 29.0 84.2 11.8 M M
19000 -13.6 7.5 225 10 5 7.9 4.4 28.7 83.7 11.6 M M
18500 -12.4 9.7 220 10 5 7.8 4.3 28.4 83.1 11.4 M M
18000 -11.3 11.7 220 10 5 7.9 4.3 28.1 82.5 11.2 M M
17500 -10.1 13.8 220 11 5 7.7 4.2 27.7 81.9 10.9 M M
17000 -9.0 15.8 220 11 6 7.7 4.2 27.4 81.3 10.6 M M
16500 -7.8 18.0 220 11 6 7.7 4.2 27.0 80.7 10.4 M M
16000 -6.1 21.0 215 11 6 7.7 4.2 26.5 79.7 10.0 M M
15500 -5.0 23.0 215 11 6 7.1 3.9 26.1 79.0 9.6 M M
15000 -4.0 24.8 210 11 6 6.9 3.8 25.6 78.1 9.2 M M
14500 -3.0 26.6 210 11 6 7.0 3.8 25.2 77.3 8.9 M M
14000 -2.0 28.4 205 11 6 7.0 3.8 24.7 76.5 8.4 M M
13500 -1.0 30.2 205 11 6 6.8 3.7 24.3 75.7 8.1 M M
13000 -0.1 31.8 200 11 6 6.1 3.3 23.7 74.7 7.5 M M
12500 0.8 33.4 195 11 6 5.9 3.2 23.1 73.6 7.0 M M
12000 1.4 34.5 195 12 6 3.8 2.1 22.3 72.1 6.2 M M
11500 2.0 35.6 195 12 6 3.9 2.1 21.4 70.5 5.3 M M
11000 2.4 36.3 190 13 7 2.6 1.4 20.3 68.6 4.3 M M
10500 2.7 36.9 190 14 7 2.6 1.4 19.2 66.6 3.2 M M
10250 2.9 37.2 190 14 7 1.9 1.1 18.6 65.5 2.6 M M
10000 3.0 37.4 185 14 7 2.3 1.3 18.0 64.4 2.0 M M
9750 3.2 37.8 185 14 7 3.5 1.9 17.5 63.4 1.5 M M
9500 3.4 38.1 185 14 7 2.6 1.4 17.0 62.5 1.0 M M
9250 3.5 38.3 185 14 7 1.3 0.7 16.3 61.4 0.4 M M
9000 3.6 38.5 185 13 7 0.8 0.4 15.7 60.2 -0.3 267 1.4
8750 3.7 38.7 185 13 6 2.6 1.4 15.0 59.0 -0.9 257 1.3
8500 3.8 38.8 185 11 6 -1.3 -0.7 14.4 57.9 -1.5 246 1.2
8250 3.5 38.3 185 10 5 -6.0 -3.3 13.3 55.9 -2.6 248 1.3
8000 3.1 37.6 190 9 4 -4.8 -2.6 12.1 53.8 -3.7 252 1.3
7750 2.7 36.9 195 7 4 -6.9 -3.8 11.0 51.7 -4.8 256 1.3
7500 2.2 36.0 195 5 3 -3.3 -1.8 9.7 49.5 -6.0 263 1.3
7250 2.2 36.0 190 4 2 1.3 0.7 9.0 48.1 -6.8 255 1.3
7000 2.3 36.1 185 3 2 -0.9 -0.5 8.2 46.8 -7.5 248 1.3
6750 2.3 36.1 170 2 1 3.6 2.0 7.5 45.5 -8.2 240 1.2
6500 2.8 37.0 175 2 1 8.3 4.5 7.3 45.2 -8.5 217 1.1
6250 3.3 37.9 165 2 1 7.9 4.4 7.2 44.9 -8.7 193 1.0
6000 3.9 39.0 150 2 1 6.9 3.8 7.0 44.6 -8.8 169 0.9
5750 4.4 39.9 140 2 1 6.7 3.7 6.8 44.2 -9.1 147 0.7
5500 5.0 41.0 135 2 1 10.5 5.7 6.7 44.0 -9.3 121 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
10/19/2024 at 0900 MDT | 10/19/2024 at 1200 MDT
|
CAPE... 0.0 LI... +0.9 | CAPE... +2.4 LI... +2.1
CINH... 0.0 K Index... +21.5 | CINH... 0.0 K Index... +23.2
|
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 -60.8 -77.4 225 18 9 1.7 1.0 | -60.9 -77.6 205 20 10 1.9 1.0
45000 -58.0 -72.4 220 23 12 1.7 0.9 | -58.1 -72.6 210 24 12 1.2 0.7
40000 -55.5 -67.9 315 10 5 1.7 0.9 | -56.2 -69.2 260 12 6 1.3 0.7
38000 -54.6 -66.3 220 12 6 1.6 0.9 | -54.6 -66.3 215 20 10 2.9 1.6
36000 -53.6 -64.5 195 32 16 1.6 0.9 | -52.8 -63.0 195 34 18 2.9 1.6
34000 -50.3 -58.5 195 39 20 9.3 5.1 | -49.2 -56.6 195 37 19 8.7 4.7
32000 -44.0 -47.2 195 35 18 9.3 5.1 | -43.4 -46.1 195 29 15 8.7 4.8
30000 -38.6 -37.5 190 32 16 8.9 4.9 | -38.1 -36.6 190 25 13 8.8 4.8
29000 -35.9 -32.6 190 31 16 8.9 4.9 | -35.5 -31.9 190 23 12 8.8 4.8
28000 -33.3 -27.9 190 30 15 9.0 4.9 | -32.8 -27.0 190 22 11 8.9 4.9
27000 -30.8 -23.4 190 27 14 8.0 4.4 | -30.4 -22.7 190 21 11 8.0 4.4
26000 -28.5 -19.3 185 25 13 8.0 4.4 | -28.0 -18.4 190 19 10 8.1 4.4
25000 -26.1 -15.0 185 22 12 8.0 4.4 | -25.6 -14.1 190 18 9 8.1 4.4
24000 -23.8 -10.8 180 20 10 7.4 4.0 | -23.3 -9.9 190 17 9 7.6 4.2
23000 -21.6 -6.9 180 16 8 7.4 4.0 | -21.0 -5.8 190 15 8 7.6 4.2
22000 -19.5 -3.1 175 13 7 7.4 4.1 | -18.8 -1.8 190 14 7 7.6 4.2
21000 -17.4 0.7 170 10 5 6.7 3.7 | -16.5 2.3 190 13 7 7.6 4.2
20000 -15.4 4.3 165 8 4 6.7 3.7 | -14.3 6.3 185 12 6 7.6 4.2
19500 -14.4 6.1 155 6 3 6.7 3.7 | -13.2 8.2 185 12 6 7.6 4.2
19000 -13.4 7.9 145 5 3 7.1 3.9 | -12.0 10.4 185 12 6 7.3 4.0
18500 -12.4 9.7 140 5 2 7.4 4.0 | -11.0 12.2 180 12 6 7.0 3.8
18000 -11.3 11.7 130 5 2 7.4 4.1 | -10.0 14.0 175 12 6 7.1 3.9
17500 -10.2 13.6 125 4 2 7.1 3.9 | -9.0 15.8 170 13 6 6.2 3.4
17000 -9.1 15.6 125 4 2 7.1 3.9 | -8.1 17.4 170 13 7 6.3 3.5
16500 -7.6 18.3 130 4 2 6.6 3.6 | -7.2 19.0 165 14 7 6.0 3.3
16000 -6.6 20.1 135 4 2 6.6 3.6 | -5.9 21.4 165 15 8 5.9 3.2
15500 -5.7 21.7 145 4 2 6.9 3.8 | -5.1 22.8 165 15 8 6.2 3.4
15000 -4.6 23.7 150 5 3 6.9 3.8 | -4.2 24.4 165 16 8 6.3 3.4
14500 -3.6 25.5 155 6 3 7.3 4.0 | -3.3 26.1 170 17 9 6.2 3.4
14000 -2.5 27.5 160 7 4 7.6 4.2 | -2.4 27.7 170 18 9 6.2 3.4
13500 -1.4 29.5 165 8 4 7.4 4.1 | -1.5 29.3 175 19 10 6.1 3.3
13000 -0.4 31.3 165 10 5 7.2 3.9 | -0.6 30.9 175 20 10 6.0 3.3
12500 0.7 33.3 170 11 6 6.6 3.6 | 0.2 32.4 175 21 11 5.9 3.2
12000 1.5 34.7 175 13 7 5.1 2.8 | 1.1 34.0 175 22 11 5.6 3.1
11500 2.2 36.0 175 14 7 5.1 2.8 | 1.9 35.4 180 22 12 5.6 3.1
11000 2.8 37.0 180 16 8 4.6 2.5 | 2.7 36.9 180 23 12 5.3 2.9
10500 3.5 38.3 180 17 9 4.1 2.2 | 3.5 38.3 180 22 12 4.4 2.4
10250 3.7 38.7 180 18 9 2.3 1.3 | 3.7 38.7 180 23 12 2.1 1.1
10000 3.9 39.0 180 18 9 3.2 1.8 | 3.9 39.0 180 23 12 4.6 2.5
9750 4.2 39.6 180 19 10 4.9 2.7 | 4.4 39.9 180 22 11 7.5 4.1
9500 4.5 40.1 185 19 10 3.3 1.8 | 4.9 40.8 180 22 11 5.3 2.9
9250 4.6 40.3 180 19 10 1.6 0.9 | 5.1 41.2 180 22 11 3.1 1.7
9000 4.7 40.5 180 20 10 2.1 1.2 | 5.4 41.7 175 22 11 4.4 2.4
8750 4.9 40.8 180 20 10 3.5 1.9 | 5.8 42.4 175 21 11 6.7 3.7
8500 5.1 41.2 180 20 10 2.0 1.1 | 6.2 43.2 175 20 10 5.2 2.9
8250 5.2 41.4 180 19 10 0.2 0.1 | 6.5 43.7 175 19 10 3.2 1.7
8000 5.2 41.4 180 19 10 1.0 0.6 | 6.8 44.2 175 19 10 4.7 2.6
7750 5.3 41.5 180 19 10 2.7 1.5 | 7.2 45.0 175 18 9 7.1 3.9
7500 5.5 41.9 180 16 8 0.0 0.0 | 7.7 45.9 175 16 8 5.7 3.1
7250 5.4 41.7 180 15 8 -2.2 -1.2 | 8.0 46.4 175 15 8 2.1 1.2
7000 5.3 41.5 185 13 7 -3.6 -2.0 | 8.2 46.8 175 14 7 7.8 4.3
6750 5.0 41.0 185 13 7 -1.2 -0.7 | 9.0 48.2 180 12 6 9.3 5.1
6500 5.2 41.4 180 11 6 3.3 1.8 | 9.4 48.9 175 11 6 5.4 3.0
6250 5.4 41.7 180 9 5 2.5 1.4 | 9.9 49.8 175 9 5 6.8 3.7
6000 5.6 42.1 175 7 4 2.8 1.5 | 10.4 50.7 170 8 4 5.1 2.8
5750 5.9 42.6 170 7 3 7.3 4.0 | 10.8 51.4 165 7 4 10.8 5.9
5500 6.8 44.2 170 5 3 14.7 8.1 | 12.1 53.8 165 6 3 24.0 13.1
10/19/2024 at 1500 MDT | 10/19/2024 at 1800 MDT
|
CAPE... +5.3 LI... +2.5 | CAPE... +5.2 LI... +2.6
CINH... -11.1 K Index... +19.3 | CINH... -97.4 K Index... +17.2
|
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 -61.0 -77.8 210 25 13 2.2 1.2 | -61.3 -78.3 215 22 11 2.3 1.2
45000 -57.9 -72.2 210 30 16 0.5 0.3 | -58.2 -72.8 205 28 15 0.3 0.2
40000 -57.1 -70.8 215 16 8 0.8 0.5 | -57.8 -72.0 195 25 13 0.8 0.4
38000 -55.1 -67.2 205 21 11 3.6 2.0 | -55.5 -67.9 190 28 14 4.1 2.3
36000 -52.9 -63.2 200 28 14 3.6 2.0 | -53.0 -63.4 190 31 16 4.1 2.2
34000 -49.1 -56.4 200 29 15 8.6 4.7 | -49.1 -56.4 190 31 16 8.3 4.6
32000 -43.3 -45.9 200 26 13 8.6 4.7 | -43.5 -46.3 195 27 14 8.4 4.6
30000 -38.0 -36.4 205 23 12 8.8 4.8 | -38.3 -36.9 195 24 12 8.7 4.8
29000 -35.4 -31.7 200 21 11 8.8 4.8 | -35.7 -32.3 195 22 11 8.7 4.8
28000 -32.8 -27.0 200 20 10 8.9 4.9 | -33.1 -27.6 195 20 10 8.7 4.8
27000 -30.3 -22.5 200 18 10 8.2 4.5 | -30.5 -22.9 195 19 10 8.9 4.9
26000 -27.8 -18.0 205 17 9 8.3 4.5 | -27.8 -18.0 195 18 9 8.9 4.9
25000 -25.4 -13.7 205 16 8 8.3 4.5 | -25.2 -13.4 195 17 9 8.9 4.9
24000 -23.0 -9.4 210 14 7 7.7 4.2 | -22.6 -8.7 195 15 8 8.6 4.7
23000 -20.7 -5.3 220 12 6 7.7 4.2 | -20.0 -4.0 195 13 7 8.6 4.7
22000 -18.4 -1.1 235 11 5 7.7 4.2 | -17.5 0.5 195 11 6 8.6 4.7
21000 -16.0 3.2 235 10 5 8.3 4.6 | -15.0 5.0 190 10 5 8.2 4.5
20000 -13.6 7.5 235 10 5 8.3 4.6 | -12.5 9.5 190 9 4 8.2 4.5
19500 -12.3 9.9 235 10 5 8.3 4.6 | -11.3 11.7 190 8 4 8.2 4.5
19000 -11.1 12.0 230 10 5 8.2 4.5 | -10.1 13.8 190 8 4 7.9 4.4
18500 -9.9 14.2 225 10 5 8.1 4.4 | -9.0 15.8 190 8 4 7.8 4.3
18000 -8.7 16.3 215 10 5 8.1 4.5 | -7.8 18.0 195 9 4 7.8 4.3
17500 -7.6 18.3 210 10 5 7.0 3.8 | -6.2 20.8 195 10 5 7.4 4.1
17000 -6.6 20.1 200 11 6 7.1 3.9 | -5.1 22.8 190 11 6 7.3 4.0
16500 -5.1 22.8 195 13 7 6.3 3.5 | -4.1 24.6 190 12 6 6.4 3.5
16000 -4.2 24.4 195 14 7 6.4 3.5 | -3.1 26.4 190 14 7 6.5 3.6
15500 -3.3 26.1 190 15 8 5.7 3.1 | -2.3 27.9 190 15 8 5.5 3.0
15000 -2.5 27.5 190 16 8 5.6 3.1 | -1.5 29.3 190 15 8 5.4 3.0
14500 -1.7 28.9 190 17 9 5.3 2.9 | -0.7 30.7 195 16 8 5.2 2.8
14000 -0.9 30.4 185 17 9 5.0 2.8 | -0.0 32.0 200 16 8 5.0 2.8
13500 -0.2 31.6 185 17 9 4.9 2.7 | 0.7 33.3 200 17 9 5.1 2.8
13000 0.4 32.7 185 18 9 4.8 2.6 | 1.4 34.5 205 16 8 5.3 2.9
12500 1.1 34.0 185 18 9 4.8 2.6 | 2.2 36.0 210 16 8 5.3 2.9
12000 1.8 35.2 185 18 9 4.9 2.7 | 2.9 37.2 215 15 8 5.1 2.8
11500 2.5 36.5 185 18 9 4.9 2.7 | 3.6 38.5 215 15 8 4.9 2.7
11000 3.2 37.8 190 18 9 5.1 2.8 | 4.2 39.6 215 14 7 3.5 1.9
10500 3.9 39.0 190 18 9 3.9 2.1 | 4.6 40.3 210 14 7 3.0 1.7
10250 4.1 39.4 190 17 9 0.8 0.4 | 4.8 40.6 210 14 7 1.6 0.9
10000 4.2 39.6 190 17 9 4.2 2.3 | 4.9 40.8 210 14 7 4.2 2.3
9750 4.7 40.5 190 17 9 7.8 4.3 | 5.3 41.5 205 13 7 6.5 3.6
9500 5.1 41.2 185 17 9 5.7 3.1 | 5.7 42.3 205 13 7 5.6 3.1
9250 5.5 41.9 185 17 9 3.4 1.9 | 6.1 43.0 200 12 6 4.4 2.4
9000 5.7 42.3 185 16 8 5.2 2.9 | 6.4 43.5 200 11 6 6.0 3.3
8750 6.3 43.3 185 16 8 8.7 4.8 | 7.0 44.6 195 11 6 8.9 4.9
8500 6.9 44.4 185 16 8 6.9 3.8 | 7.6 45.7 185 11 6 7.8 4.3
8250 7.2 45.0 185 15 8 4.7 2.6 | 8.1 46.6 185 10 5 6.4 3.5
8000 7.6 45.7 185 14 7 6.2 3.4 | 8.6 47.5 185 9 5 7.2 4.0
7750 8.2 46.8 185 13 7 9.0 4.9 | 9.2 48.6 180 9 5 8.7 4.8
7500 8.8 47.8 185 13 6 8.5 4.7 | 9.8 49.6 180 10 5 7.7 4.2
7250 9.4 48.9 180 12 6 6.3 3.5 | 10.3 50.5 180 9 5 6.4 3.5
7000 9.9 49.8 180 11 5 8.6 4.7 | 10.8 51.4 175 9 5 6.8 3.7
6750 10.6 51.1 175 10 5 11.5 6.3 | 11.3 52.3 175 9 5 7.3 4.0
6500 11.5 52.7 170 9 5 10.5 5.8 | 11.9 53.4 165 9 5 7.8 4.3
6250 12.2 54.0 170 8 4 9.7 5.3 | 12.5 54.5 160 9 4 7.3 4.0
6000 12.9 55.2 170 8 4 9.1 5.0 | 13.0 55.4 155 8 4 8.5 4.7
5750 13.7 56.7 165 8 4 12.1 6.7 | 13.7 56.7 160 8 4 7.7 4.2
5500 14.8 58.6 165 7 4 19.6 10.7 | 14.1 57.4 155 6 3 2.7 1.5
________________________________________________________________________________
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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