Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
813
UXUS97 KBOU 180039
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1738 MST Sunday, November 17, 2024
This forecast is for Monday, November 18, 2024:
If the trigger temperature of 51.4 F/10.8 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 412 ft/min (2.1 m/s)
Maximum height of thermals.................. 11225 ft MSL (5842 ft AGL)
Forecast maximum temperature................... 57.0 F/14.3 C
Time of trigger temperature.................... 1130 MST
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................. 9385 ft MSL (4002 ft AGL)
Thermal soaring outlook for Tuesday 11/19...... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1700 MST)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1700 MST)................ Weak PVA
Potential height of wave....................... 16193 ft MSL (10810 ft AGL)
Wave soaring outlook for Tuesday 11/19......... Fair
Remarks... None
Sunrise/Sunset.................... 06:48:27 / 16:41:08 MST
Total possible sunshine........... 9 hr 52 min 41 sec (592 min 41 sec)
Altitude of sun at 11:44:47 MST... 30.65 degrees
Upper air data from numerical model forecast valid on 11/18/2024 at 0500 MST
Freezing level.................. 5733 ft MSL (350 ft AGL)
Additional freezing level....... 8537 ft MSL (3154 ft AGL)
Convective condensation level... 20804 ft MSL (15421 ft AGL)
Lifted condensation level....... 16590 ft MSL (11207 ft AGL)
Lifted index.................... +10.6
K index......................... -20.0
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 -58.4 -73.1 225 29 15 2.8 1.5 M M M M M
45000 -54.0 -65.2 225 28 14 2.2 1.2 M M M M M
40000 -50.7 -59.3 220 34 18 2.2 1.2 M M M M M
38000 -49.7 -57.5 220 38 19 1.0 0.5 M M M M M
36000 -49.2 -56.6 215 41 21 1.0 0.5 M M M M M
34000 -47.8 -54.0 210 48 25 7.2 4.0 M M M M M
32000 -43.7 -46.7 200 64 33 7.0 3.8 M M M M M
30000 -39.5 -39.1 195 77 40 7.0 3.8 37.4 99.4 17.7 M M
29000 -37.4 -35.3 200 72 37 7.1 3.9 36.2 97.2 17.0 M M
28000 -35.3 -31.5 205 68 35 7.1 3.9 35.2 95.4 16.4 M M
27000 -33.2 -27.8 210 65 33 7.2 3.9 34.3 93.8 15.9 M M
26000 -31.1 -24.0 215 60 31 6.6 3.6 33.1 91.6 15.1 M M
25000 -29.1 -20.4 225 57 29 6.6 3.6 31.9 89.4 14.3 M M
24000 -27.1 -16.8 235 55 28 6.6 3.6 30.8 87.4 13.6 M M
23000 -25.3 -13.5 240 52 27 5.7 3.1 29.4 85.0 12.7 M M
22000 -23.6 -10.5 240 46 24 5.6 3.1 27.9 82.2 11.6 M M
21000 -22.0 -7.6 245 40 21 5.4 3.0 26.5 79.7 10.5 M M
20000 -19.3 -2.7 245 33 17 7.5 4.1 25.3 77.5 9.6 M M
19500 -18.2 -0.8 245 30 16 7.5 4.1 24.9 76.8 9.4 M M
19000 -17.0 1.4 245 28 14 7.5 4.1 24.5 76.1 9.1 M M
18500 -15.9 3.4 250 25 13 7.3 4.0 24.2 75.5 8.9 M M
18000 -15.1 4.8 250 20 11 3.7 2.0 23.4 74.1 8.2 M M
17500 -14.5 5.9 255 15 8 3.9 2.1 22.4 72.3 7.4 M M
17000 -13.9 7.0 265 11 6 4.7 2.6 21.4 70.6 6.6 M M
16500 -13.2 8.2 265 9 5 5.0 2.7 20.6 69.1 5.9 M M
16000 -12.4 9.7 275 7 3 5.6 3.0 19.8 67.7 5.2 M M
15500 -11.4 11.5 280 6 3 7.0 3.8 19.3 66.7 4.8 M M
15000 -10.4 13.3 285 5 3 7.1 3.9 18.8 65.9 4.4 M M
14500 -9.5 14.9 290 5 2 5.8 3.2 18.3 64.9 3.9 M M
14000 -8.6 16.5 300 4 2 5.9 3.2 17.6 63.8 3.3 M M
13500 -7.7 18.1 310 4 2 6.4 3.5 17.1 62.7 2.7 M M
13000 -6.8 19.8 315 4 2 6.5 3.6 16.5 61.7 2.3 M M
12500 -5.8 21.6 315 4 2 5.9 3.3 16.0 60.7 1.7 M M
12000 -5.0 23.0 305 3 2 5.9 3.2 15.3 59.6 1.2 M M
11500 -4.1 24.6 295 3 2 4.4 2.4 14.6 58.3 0.5 M M
11000 -3.6 25.5 270 3 2 3.9 2.2 13.7 56.7 -0.3 399 2.0
10500 -2.9 26.8 250 4 2 4.7 2.6 12.8 55.1 -1.2 366 1.9
10250 -2.6 27.3 240 4 2 5.3 2.9 12.4 54.4 -1.5 347 1.8
10000 -2.2 28.0 230 4 2 3.8 2.1 12.1 53.7 -1.9 329 1.7
9750 -2.0 28.4 225 5 2 3.7 2.0 11.5 52.8 -2.4 314 1.6
9500 -1.6 29.1 220 5 3 5.6 3.1 11.2 52.1 -2.8 296 1.5
9250 -1.2 29.8 215 6 3 6.8 3.7 10.9 51.6 -3.1 276 1.4
9000 -0.7 30.7 215 7 3 4.1 2.3 10.6 51.1 -3.4 255 1.3
8750 -0.5 31.1 210 7 4 3.8 2.1 10.1 50.1 -3.9 241 1.2
8500 -0.1 31.8 215 7 4 6.6 3.6 9.7 49.5 -4.2 221 1.1
8250 0.4 32.7 220 7 4 7.4 4.1 9.5 49.1 -4.5 199 1.0
8000 0.9 33.6 225 7 4 4.7 2.6 9.3 48.7 -4.7 176 0.9
7750 1.1 34.0 225 7 4 2.9 1.6 8.8 47.8 -5.2 162 0.8
7500 1.4 34.5 235 7 4 4.4 2.4 8.3 47.0 -5.7 146 0.7
7250 1.7 35.1 245 8 4 3.8 2.1 7.9 46.2 -6.1 130 0.7
7000 2.0 35.6 255 8 4 4.8 2.6 7.5 45.4 -6.6 114 0.6
6750 2.4 36.3 260 8 4 3.2 1.8 7.1 44.7 -7.0 96 0.5
6500 2.5 36.5 255 9 4 1.7 0.9 6.5 43.6 -7.6 85 0.4
6250 2.6 36.7 255 9 5 1.1 0.6 5.9 42.5 -8.3 74 0.4
6000 2.4 36.3 250 9 5 -6.5 -3.6 5.0 41.0 -9.2 72 0.4
5750 -1.0 30.2 230 7 4 -36.1 -19.8 0.2 32.3 -14.1 160 0.8
5500 -3.4 25.9 210 5 2 -16.5 -9.0 -2.8 26.9 -17.3 225 1.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/18/2024 at 0800 MST | 11/18/2024 at 1100 MST
|
CAPE... 0.0 LI... +6.7 | CAPE... 0.0 LI... +4.2
CINH... -0.1 K Index... -8.1 | CINH... -0.1 K Index... +4.8
|
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 -59.4 -74.9 250 28 14 2.3 1.3 | -59.5 -75.1 240 30 15 2.9 1.6
45000 -55.6 -68.1 260 27 14 3.7 2.0 | -54.9 -66.8 260 36 18 4.0 2.2
40000 -50.3 -58.5 250 23 12 3.5 1.9 | -49.1 -56.4 260 41 21 3.9 2.1
38000 -48.8 -55.8 245 22 11 1.6 0.9 | -47.4 -53.3 255 36 19 1.9 1.0
36000 -47.9 -54.2 240 21 11 1.6 0.9 | -46.3 -51.3 245 27 14 1.9 1.0
34000 -46.8 -52.2 225 20 11 4.3 2.4 | -45.1 -49.2 230 20 11 3.5 1.9
32000 -44.1 -47.4 200 34 18 4.5 2.5 | -42.7 -44.9 200 32 16 4.0 2.2
30000 -40.7 -41.3 190 52 27 8.1 4.5 | -39.8 -39.6 185 47 24 7.4 4.1
29000 -38.3 -36.9 190 53 27 7.9 4.4 | -37.7 -35.9 190 48 25 7.1 3.9
28000 -35.9 -32.6 190 55 28 8.0 4.4 | -35.5 -31.9 190 49 25 7.1 3.9
27000 -33.5 -28.3 190 57 29 8.0 4.4 | -33.4 -28.1 195 50 26 7.2 4.0
26000 -31.1 -24.0 195 54 28 8.1 4.4 | -31.4 -24.5 200 44 23 6.4 3.5
25000 -28.7 -19.7 205 51 26 8.1 4.4 | -29.5 -21.1 210 37 19 6.4 3.5
24000 -26.3 -15.3 210 49 25 8.2 4.5 | -27.6 -17.7 225 31 16 6.4 3.5
23000 -24.1 -11.4 215 44 22 6.9 3.8 | -26.0 -14.8 245 25 13 4.3 2.3
22000 -22.0 -7.6 225 37 19 6.8 3.8 | -24.7 -12.5 265 19 10 4.2 2.3
21000 -20.0 -4.0 235 32 16 7.2 4.0 | -23.5 -10.3 295 17 9 3.9 2.2
20000 -18.6 -1.5 245 24 12 3.6 2.0 | -21.6 -6.9 310 17 9 7.3 4.0
19500 -18.1 -0.6 250 20 10 3.6 2.0 | -20.5 -4.9 315 16 8 7.3 4.0
19000 -17.5 0.5 260 16 8 3.6 2.0 | -19.5 -3.1 315 16 8 7.3 4.0
18500 -17.0 1.4 275 13 7 3.6 2.0 | -18.4 -1.1 320 15 8 7.3 4.0
18000 -16.4 2.5 290 11 6 4.9 2.7 | -17.3 0.9 325 15 8 7.7 4.2
17500 -15.6 3.9 300 11 5 5.4 2.9 | -16.1 3.0 325 14 7 7.9 4.3
17000 -14.4 6.1 310 10 5 6.5 3.5 | -14.4 6.1 330 13 7 7.2 4.0
16500 -13.4 7.9 315 10 5 6.7 3.7 | -13.4 7.9 330 12 6 7.1 3.9
16000 -12.4 9.7 315 10 5 6.8 3.7 | -12.3 9.9 330 12 6 7.0 3.9
15500 -11.4 11.5 315 10 5 7.0 3.8 | -11.3 11.7 330 11 6 7.0 3.8
15000 -10.3 13.5 315 9 5 7.0 3.8 | -10.3 13.5 330 11 6 7.0 3.9
14500 -9.4 15.1 315 9 5 6.3 3.5 | -9.2 15.4 330 11 6 7.1 3.9
14000 -8.4 16.9 310 9 4 6.4 3.5 | -8.2 17.2 325 11 6 7.1 3.9
13500 -7.5 18.5 310 8 4 6.2 3.4 | -7.2 19.0 325 12 6 6.7 3.7
13000 -6.6 20.1 305 8 4 6.2 3.4 | -6.2 20.8 320 12 6 6.7 3.7
12500 -5.7 21.7 305 8 4 6.1 3.3 | -5.2 22.6 320 12 6 6.3 3.5
12000 -4.8 23.4 305 8 4 6.0 3.3 | -4.2 24.4 320 13 7 6.3 3.4
11500 -3.9 25.0 300 9 4 6.1 3.3 | -3.3 26.1 315 13 7 6.2 3.4
11000 -3.0 26.6 305 9 5 6.2 3.4 | -2.4 27.7 320 14 7 6.2 3.4
10500 -2.1 28.2 305 10 5 4.5 2.5 | -1.5 29.3 320 14 7 4.7 2.6
10250 -1.8 28.8 300 10 5 4.1 2.3 | -1.2 29.8 320 14 7 4.4 2.4
10000 -1.4 29.5 300 11 6 7.2 3.9 | -0.8 30.6 320 15 7 6.1 3.4
9750 -0.8 30.6 305 12 6 8.0 4.4 | -0.3 31.5 320 15 7 6.6 3.6
9500 -0.3 31.5 305 12 6 5.8 3.2 | 0.2 32.4 320 15 8 6.0 3.3
9250 0.1 32.2 305 12 6 5.4 2.9 | 0.6 33.1 320 15 8 5.7 3.1
9000 0.5 32.9 305 12 6 5.9 3.3 | 1.1 34.0 320 15 8 6.2 3.4
8750 1.0 33.8 300 13 7 6.3 3.4 | 1.6 34.9 315 15 8 7.2 4.0
8500 1.5 34.7 305 13 7 5.9 3.2 | 2.1 35.8 315 14 7 7.6 4.2
8250 1.9 35.4 305 13 7 6.0 3.3 | 2.7 36.9 315 15 7 7.8 4.3
8000 2.3 36.1 305 13 7 5.6 3.1 | 3.3 37.9 315 15 8 7.4 4.0
7750 2.7 36.9 300 14 7 5.2 2.8 | 3.8 38.8 315 14 7 6.1 3.4
7500 3.1 37.6 300 14 7 5.2 2.9 | 4.2 39.6 315 15 8 5.4 3.0
7250 3.5 38.3 300 13 7 5.3 2.9 | 4.7 40.5 315 16 8 6.2 3.4
7000 3.9 39.0 300 13 7 4.9 2.7 | 5.1 41.2 315 17 8 3.8 2.1
6750 4.2 39.6 305 14 7 4.0 2.2 | 5.3 41.5 315 15 8 3.0 1.7
6500 4.5 40.1 305 13 6 3.8 2.1 | 5.6 42.1 315 13 7 5.0 2.8
6250 4.8 40.6 305 11 6 3.2 1.7 | 5.9 42.6 310 10 5 4.0 2.2
6000 4.8 40.6 300 10 5 -4.9 -2.7 | 6.2 43.2 305 8 4 6.5 3.5
5750 3.7 38.7 295 8 4 -23.1 -12.7 | 6.9 44.4 315 7 4 12.6 6.9
5500 1.3 34.3 265 4 2 -38.1 -20.9 | 8.0 46.4 315 6 3 16.4 9.0
11/18/2024 at 1400 MST | 11/18/2024 at 1700 MST
|
CAPE... 0.0 LI... +3.2 | CAPE... 0.0 LI... +2.7
CINH... 0.0 K Index... +12.3 | CINH... 0.0 K Index... +15.9
|
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 -59.0 -74.2 235 39 20 3.0 1.7 | -59.0 -74.2 230 42 22 3.4 1.9
45000 -54.5 -66.1 240 42 21 3.8 2.1 | -53.9 -65.0 225 51 26 4.3 2.4
40000 -47.7 -53.9 240 53 28 4.3 2.4 | -46.2 -51.2 225 62 32 4.9 2.7
38000 -46.0 -50.8 240 53 27 1.4 0.8 | -44.2 -47.6 225 63 32 1.9 1.0
36000 -45.2 -49.4 235 47 24 1.4 0.8 | -43.1 -45.6 225 59 31 1.8 1.0
34000 -44.3 -47.7 230 43 22 3.0 1.6 | -42.0 -43.6 225 56 29 1.5 0.8
32000 -42.0 -43.6 215 37 19 3.8 2.1 | -41.4 -42.5 225 48 25 1.1 0.6
30000 -39.8 -39.6 200 33 17 4.8 2.6 | -40.7 -41.3 220 40 21 1.5 0.8
29000 -37.6 -35.7 205 31 16 6.0 3.3 | -39.6 -39.3 220 39 20 4.1 2.3
28000 -35.8 -32.4 215 30 16 6.0 3.3 | -38.1 -36.6 225 38 20 4.1 2.2
27000 -34.0 -29.2 220 30 15 6.1 3.3 | -36.9 -34.4 230 38 20 4.1 2.2
26000 -32.5 -26.5 230 28 14 4.7 2.6 | -35.4 -31.7 235 35 18 5.2 2.9
25000 -31.1 -24.0 240 25 13 4.7 2.6 | -33.9 -29.0 245 32 16 5.2 2.9
24000 -29.6 -21.3 255 23 12 4.8 2.6 | -32.3 -26.1 255 29 15 5.3 2.9
23000 -28.0 -18.4 265 22 11 6.4 3.5 | -30.5 -22.9 260 28 14 7.4 4.1
22000 -26.1 -15.0 275 20 10 6.5 3.6 | -28.2 -18.8 260 27 14 7.5 4.1
21000 -24.2 -11.6 290 19 10 6.5 3.5 | -26.0 -14.8 265 26 14 7.4 4.1
20000 -22.1 -7.8 295 19 10 7.4 4.1 | -23.6 -10.5 265 25 13 8.7 4.8
19500 -21.0 -5.8 300 18 9 7.4 4.1 | -22.3 -8.1 265 24 12 8.7 4.8
19000 -19.9 -3.8 300 18 9 7.4 4.1 | -21.0 -5.8 265 23 12 8.7 4.8
18500 -18.8 -1.8 305 18 9 7.4 4.1 | -19.7 -3.5 265 21 11 8.8 4.8
18000 -17.7 0.1 305 18 9 8.0 4.4 | -18.4 -1.1 265 20 11 7.7 4.2
17500 -16.4 2.5 305 17 9 8.2 4.5 | -17.4 0.7 270 20 10 7.3 4.0
17000 -15.2 4.6 305 17 9 8.2 4.5 | -16.3 2.7 270 19 10 7.3 4.0
16500 -14.0 6.8 305 17 9 7.9 4.3 | -15.2 4.6 270 18 9 7.5 4.1
16000 -12.9 8.8 305 16 8 8.0 4.4 | -14.1 6.6 270 17 9 7.6 4.2
15500 -11.7 10.9 305 16 8 7.7 4.2 | -13.1 8.4 275 15 8 6.7 3.7
15000 -10.6 12.9 305 15 8 7.7 4.2 | -12.1 10.2 275 14 7 6.6 3.6
14500 -9.4 15.1 305 15 8 7.4 4.1 | -11.1 12.0 280 13 7 6.2 3.4
14000 -7.8 18.0 305 14 7 7.3 4.0 | -10.3 13.5 285 12 6 6.0 3.3
13500 -6.8 19.8 305 14 7 6.1 3.4 | -9.4 15.1 290 10 5 6.2 3.4
13000 -5.9 21.4 305 15 8 6.1 3.3 | -7.9 17.8 295 8 4 6.6 3.6
12500 -5.0 23.0 310 15 8 5.6 3.1 | -6.8 19.8 300 7 4 8.3 4.6
12000 -4.2 24.4 310 15 8 5.5 3.0 | -5.6 21.9 305 8 4 8.5 4.7
11500 -3.3 26.1 315 14 7 5.8 3.2 | -4.2 24.4 305 8 4 9.7 5.3
11000 -2.4 27.7 315 14 7 6.0 3.3 | -2.7 27.1 305 11 6 10.1 5.5
10500 -1.5 29.3 320 13 7 7.0 3.8 | -1.3 29.7 305 14 7 8.3 4.5
10250 -0.9 30.4 320 14 7 7.7 4.2 | -0.7 30.7 305 15 8 7.9 4.3
10000 -0.4 31.3 315 14 7 8.0 4.4 | -0.1 31.8 305 16 8 9.3 5.1
9750 0.2 32.4 315 14 7 8.3 4.5 | 0.6 33.1 300 18 9 8.2 4.5
9500 0.9 33.6 315 15 8 8.5 4.7 | 1.1 34.0 300 19 10 5.1 2.8
9250 1.5 34.7 310 16 8 8.8 4.8 | 1.4 34.5 300 20 10 4.6 2.5
9000 2.1 35.8 310 17 9 8.2 4.5 | 1.8 35.2 295 21 11 4.2 2.3
8750 2.7 36.9 305 20 10 6.4 3.5 | 2.1 35.8 295 22 11 3.8 2.1
8500 3.1 37.6 305 22 11 4.6 2.5 | 2.3 36.1 295 23 12 4.0 2.2
8250 3.5 38.3 305 24 12 5.5 3.0 | 2.6 36.7 295 23 12 4.3 2.4
8000 3.8 38.8 305 25 13 1.2 0.7 | 2.9 37.2 295 24 12 3.1 1.7
7750 3.8 38.8 300 26 14 3.7 2.0 | 3.1 37.6 290 24 12 3.6 2.0
7500 4.5 40.1 300 24 12 9.8 5.4 | 3.5 38.3 295 23 12 5.2 2.9
7250 5.1 41.2 305 22 11 8.5 4.6 | 3.9 39.0 295 21 11 5.0 2.7
7000 5.8 42.4 305 20 10 7.8 4.3 | 4.2 39.6 295 20 10 4.5 2.4
6750 6.3 43.3 305 18 9 8.6 4.7 | 4.6 40.3 300 19 10 6.2 3.4
6500 7.1 44.8 305 17 9 10.3 5.6 | 5.1 41.2 305 17 9 8.1 4.4
6250 7.8 46.0 305 16 8 10.5 5.7 | 5.7 42.3 305 16 8 7.5 4.1
6000 8.5 47.3 305 15 8 8.0 4.4 | 6.3 43.3 310 15 7 6.9 3.8
5750 9.1 48.4 305 14 7 8.4 4.6 | 6.7 44.1 315 13 7 3.9 2.2
5500 10.0 50.0 305 11 6 16.7 9.2 | 6.8 44.2 320 9 4 0.6 0.3
________________________________________________________________________________
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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