Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 100034
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1834 MDT Tuesday, April 9, 2024
This forecast is for Wednesday, April 10, 2024:
If the trigger temperature of 50.9 F/10.5 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 177 ft/min (0.9 m/s)
Maximum height of thermals.................. 12059 ft MSL (6787 ft AGL)
Forecast maximum temperature................... 53.0 F/12.1 C
Time of trigger temperature.................... 1245 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................. 6365 ft MSL (1093 ft AGL)
Thermal soaring outlook for Thursday 04/11..... Good
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 PVA
Potential height of wave....................... 15107 ft MSL (9835 ft AGL)
Wave soaring outlook for Thursday 04/11........ Poor
Remarks...
Sunrise/Sunset.................... 06:28:06 / 19:33:01 MDT
Total possible sunshine........... 13 hr 4 min 55 sec (784 min 55 sec)
Altitude of sun at 13:00:34 MDT... 58.57 degrees
Upper air data from numerical model forecast valid on 04/10/2024 at 0600 MDT
Freezing level.................. 8687 ft MSL (3415 ft AGL)
Convective condensation level... 12004 ft MSL (6732 ft AGL)
Lifted condensation level....... 12047 ft MSL (6775 ft AGL)
Lifted index.................... +2.4
K index......................... +19.7
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 -55.1 -67.2 270 25 13 1.7 0.9 M M M M M
45000 -52.6 -62.7 280 32 17 1.8 1.0 M M M M M
40000 -54.2 -65.6 300 42 21 -1.2 -0.7 M M M M M
38000 -54.3 -65.7 305 45 23 2.0 1.1 M M M M M
36000 -53.1 -63.6 315 47 24 1.9 1.1 M M M M M
34000 -51.9 -61.4 325 50 26 2.6 1.4 M M M M M
32000 -49.7 -57.5 325 44 23 3.8 2.1 M M M M M
30000 -47.4 -53.3 325 39 20 4.8 2.6 M M M M M
29000 -45.6 -50.1 325 36 19 6.1 3.4 28.0 82.3 12.3 M M
28000 -43.3 -45.9 325 32 17 6.1 3.4 26.2 79.1 11.1 M M
27000 -41.5 -42.7 325 30 15 6.0 3.3 24.9 76.8 10.3 M M
26000 -39.2 -38.6 325 29 15 7.9 4.3 24.0 75.1 9.7 M M
25000 -36.9 -34.4 325 29 15 7.9 4.3 23.2 73.8 9.2 M M
24000 -34.5 -30.1 325 29 15 8.0 4.4 22.6 72.7 8.9 M M
23000 -32.3 -26.1 325 29 15 7.3 4.0 21.8 71.2 8.2 M M
22000 -30.1 -22.2 325 29 15 7.3 4.0 20.9 69.5 7.6 M M
21000 -27.9 -18.2 325 28 14 6.5 3.6 20.1 68.2 7.0 M M
20000 -26.5 -15.7 320 24 12 4.6 2.5 18.2 64.8 5.5 M M
19500 -25.8 -14.4 320 22 11 4.6 2.5 17.3 63.2 4.7 M M
19000 -25.1 -13.2 320 20 10 4.7 2.6 16.4 61.6 4.0 M M
18500 -24.5 -12.1 320 18 9 5.2 2.9 15.6 60.1 3.3 M M
18000 -23.5 -10.3 320 17 9 7.8 4.3 15.1 59.2 2.8 M M
17500 -22.3 -8.1 320 17 9 7.5 4.1 14.7 58.5 2.5 M M
17000 -21.1 -6.0 320 17 9 9.6 5.2 14.5 58.1 2.3 M M
16500 -19.7 -3.5 325 17 9 9.6 5.3 14.5 58.1 2.3 M M
16000 -18.3 -0.9 325 18 9 8.6 4.7 14.5 58.0 2.2 M M
15500 -17.1 1.2 330 18 10 8.0 4.4 14.1 57.4 1.9 M M
15000 -15.9 3.4 330 19 10 7.9 4.4 13.8 56.9 1.7 M M
14500 -14.7 5.5 330 19 10 8.0 4.4 13.5 56.4 1.4 M M
14000 -12.9 8.8 335 20 10 8.4 4.6 13.1 55.6 1.0 M M
13500 -11.7 10.9 335 20 10 8.5 4.7 12.9 55.2 0.8 M M
13000 -10.5 13.1 340 20 10 7.8 4.3 12.7 54.8 0.6 M M
12500 -9.4 15.1 340 20 10 7.5 4.1 12.3 54.1 0.2 M M
12000 -8.2 17.2 345 20 10 8.0 4.4 12.0 53.5 -0.1 562 2.9
11500 -7.0 19.4 345 20 10 8.3 4.6 11.7 53.1 -0.3 511 2.6
11000 -5.8 21.6 350 20 10 8.7 4.8 11.5 52.7 -0.6 459 2.3
10500 -4.5 23.9 350 21 11 9.8 5.4 11.3 52.4 -0.7 405 2.1
10250 -3.8 25.2 350 21 11 4.7 2.6 11.3 52.3 -0.8 379 1.9
10000 -3.6 25.5 350 21 11 5.6 3.1 10.7 51.3 -1.4 365 1.9
9750 -2.9 26.8 350 21 11 12.0 6.6 10.8 51.4 -1.3 335 1.7
9500 -2.0 28.4 350 22 11 11.8 6.5 10.9 51.6 -1.2 302 1.5
9250 -1.2 29.8 350 22 11 9.2 5.1 11.0 51.9 -1.1 269 1.4
9000 -0.7 30.7 350 22 11 6.5 3.5 10.8 51.5 -1.3 246 1.3
8750 -0.1 31.8 350 21 11 9.2 5.0 10.7 51.2 -1.5 222 1.1
8500 0.7 33.3 345 21 11 10.6 5.8 10.7 51.2 -1.4 192 1.0
8250 1.4 34.5 345 21 11 8.9 4.9 10.7 51.3 -1.4 162 0.8
8000 2.0 35.6 340 20 10 7.7 4.2 10.6 51.0 -1.6 137 0.7
7750 2.6 36.7 340 19 10 8.4 4.6 10.4 50.8 -1.7 112 0.6
7500 3.2 37.8 335 18 9 8.0 4.4 10.3 50.6 -1.8 86 0.4
7250 3.7 38.7 330 17 9 6.8 3.8 10.2 50.3 -2.0 62 0.3
7000 4.2 39.6 330 16 8 6.6 3.6 9.9 49.9 -2.3 41 0.2
6750 4.7 40.5 325 15 8 6.4 3.5 9.7 49.4 -2.5 19 0.1
6500 5.2 41.4 325 14 7 6.0 3.3 9.4 48.9 -2.8 M M
6250 5.6 42.1 320 12 6 5.7 3.1 9.1 48.4 -3.1 M M
6000 6.0 42.8 320 11 6 6.5 3.6 8.8 47.9 -3.5 M M
5750 6.4 43.5 320 10 5 3.5 1.9 8.5 47.4 -3.8 M M
5500 6.3 43.3 310 7 4 -5.3 -2.9 7.7 45.9 -4.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/10/2024 at 0900 MDT | 04/10/2024 at 1200 MDT
|
CAPE... +17.8 LI... +1.2 | CAPE... +87.0 LI... +0.5
CINH... -13.2 K Index... +16.2 | CINH... -2.1 K Index... +19.3
|
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 -57.0 -70.6 265 21 11 1.3 0.7 | -56.5 -69.7 270 23 12 0.7 0.4
45000 -55.0 -67.0 285 26 13 1.4 0.8 | -55.4 -67.7 280 25 13 0.8 0.5
40000 -54.9 -66.8 310 38 20 -0.0 -0.0 | -55.9 -68.6 310 38 19 -0.4 -0.2
38000 -54.5 -66.1 315 43 22 1.9 1.1 | -55.6 -68.1 315 42 22 1.6 0.9
36000 -53.4 -64.1 320 46 23 1.9 1.0 | -54.7 -66.5 315 43 22 1.6 0.9
34000 -52.2 -62.0 325 49 25 3.2 1.8 | -53.7 -64.7 320 44 23 4.0 2.2
32000 -49.4 -56.9 330 51 26 4.7 2.6 | -50.3 -58.5 330 52 27 5.7 3.1
30000 -46.5 -51.7 330 53 27 5.4 3.0 | -46.8 -52.2 335 61 31 6.4 3.5
29000 -44.7 -48.5 335 51 26 6.0 3.3 | -44.3 -47.7 335 61 31 6.7 3.7
28000 -42.5 -44.5 335 48 25 6.0 3.3 | -42.3 -44.1 335 60 31 6.7 3.7
27000 -40.7 -41.3 335 47 24 6.0 3.3 | -40.3 -40.5 335 60 31 6.8 3.7
26000 -38.8 -37.8 335 43 22 6.3 3.4 | -38.1 -36.6 335 56 29 7.5 4.1
25000 -36.9 -34.4 335 40 20 6.3 3.4 | -35.9 -32.6 335 52 27 7.5 4.1
24000 -35.1 -31.2 330 36 19 6.2 3.4 | -33.6 -28.5 335 48 24 7.6 4.2
23000 -32.9 -27.2 330 34 18 7.4 4.1 | -31.6 -24.9 335 43 22 6.6 3.6
22000 -30.7 -23.3 330 33 17 7.4 4.0 | -29.6 -21.3 330 40 20 6.6 3.6
21000 -28.5 -19.3 330 32 16 7.1 3.9 | -27.6 -17.7 330 36 18 6.4 3.5
20000 -26.6 -15.9 330 31 16 6.4 3.5 | -25.8 -14.4 330 34 18 6.1 3.3
19500 -25.7 -14.3 330 31 16 6.4 3.5 | -24.9 -12.8 325 34 17 6.1 3.4
19000 -24.7 -12.5 325 31 16 6.4 3.5 | -24.0 -11.2 325 33 17 6.1 3.4
18500 -23.8 -10.8 325 31 16 6.5 3.6 | -23.1 -9.6 325 32 17 6.0 3.3
18000 -22.8 -9.0 325 30 15 6.7 3.7 | -22.3 -8.1 325 31 16 5.4 3.0
17500 -21.8 -7.2 325 29 15 6.7 3.6 | -21.5 -6.7 320 30 15 5.4 2.9
17000 -20.8 -5.4 320 28 14 7.3 4.0 | -20.6 -5.1 320 29 15 6.6 3.6
16500 -19.7 -3.5 320 26 14 7.3 4.0 | -19.7 -3.5 320 28 15 6.6 3.6
16000 -18.7 -1.7 320 25 13 7.4 4.1 | -18.1 -0.6 315 27 14 7.8 4.3
15500 -17.5 0.5 320 24 12 7.5 4.1 | -17.0 1.4 315 27 14 7.7 4.2
15000 -15.9 3.4 320 22 12 7.3 4.0 | -15.8 3.6 315 26 13 8.4 4.6
14500 -14.8 5.4 325 21 11 7.3 4.0 | -14.6 5.7 315 25 13 8.5 4.6
14000 -13.7 7.3 325 21 11 7.4 4.0 | -13.4 7.9 315 25 13 8.2 4.5
13500 -12.6 9.3 330 20 10 7.4 4.1 | -12.2 10.0 315 23 12 8.1 4.5
13000 -11.5 11.3 335 19 10 7.7 4.2 | -11.0 12.2 310 22 12 8.0 4.4
12500 -10.4 13.3 335 18 9 7.8 4.3 | -9.8 14.4 315 21 11 7.9 4.4
12000 -9.2 15.4 340 18 9 8.3 4.5 | -8.6 16.5 315 20 10 7.9 4.3
11500 -8.0 17.6 345 18 9 8.5 4.7 | -7.5 18.5 315 18 9 7.9 4.3
11000 -6.7 19.9 345 18 9 9.1 5.0 | -6.3 20.7 320 17 9 8.1 4.5
10500 -5.3 22.5 345 18 9 10.6 5.8 | -5.2 22.6 330 15 8 9.5 5.2
10250 -4.7 23.5 345 18 9 3.9 2.1 | -4.6 23.7 335 14 7 3.1 1.7
10000 -4.6 23.7 345 18 9 4.7 2.6 | -4.5 23.9 340 13 7 5.2 2.9
9750 -3.8 25.2 345 18 9 12.9 7.1 | -3.7 25.3 340 13 7 13.2 7.2
9500 -2.9 26.8 345 18 9 12.5 6.9 | -2.8 27.0 345 13 7 12.0 6.6
9250 -2.0 28.4 345 19 10 9.9 5.4 | -1.9 28.6 345 13 7 9.6 5.3
9000 -1.4 29.5 345 19 10 7.1 3.9 | -1.4 29.5 350 12 6 7.3 4.0
8750 -0.8 30.6 345 19 10 9.7 5.3 | -0.7 30.7 350 12 6 10.3 5.7
8500 -0.0 32.0 340 19 10 10.8 6.0 | 0.1 32.2 350 12 6 11.1 6.1
8250 0.7 33.3 340 19 10 8.8 4.9 | 0.9 33.6 355 12 6 9.2 5.0
8000 1.3 34.3 335 18 9 7.4 4.1 | 1.5 34.7 360 12 6 8.0 4.4
7750 1.9 35.4 335 17 9 8.8 4.9 | 2.2 36.0 360 12 6 11.0 6.0
7500 2.6 36.7 330 16 8 8.5 4.7 | 3.1 37.6 360 12 6 10.8 5.9
7250 3.1 37.6 330 15 8 6.9 3.8 | 3.7 38.7 360 12 6 8.1 4.5
7000 3.6 38.5 330 14 7 6.0 3.3 | 4.3 39.7 360 12 6 6.9 3.8
6750 4.1 39.4 325 13 7 8.9 4.9 | 4.9 40.8 005 12 6 12.6 6.9
6500 4.9 40.8 325 12 6 10.1 5.5 | 6.1 43.0 360 11 6 13.4 7.4
6250 5.5 41.9 325 10 5 8.6 4.7 | 6.8 44.2 360 11 6 9.5 5.2
6000 6.1 43.0 325 9 5 8.2 4.5 | 7.6 45.7 005 11 6 9.1 5.0
5750 6.8 44.2 325 7 4 11.1 6.1 | 8.3 46.9 005 11 6 14.6 8.0
5500 7.9 46.2 325 7 3 19.3 10.6 | 10.0 50.0 005 10 5 29.7 16.3
04/10/2024 at 1500 MDT | 04/10/2024 at 1800 MDT
|
CAPE... +47.1 LI... -0.4 | CAPE... +16.2 LI... +1.6
CINH... -11.3 K Index... +23.3 | CINH... -49.6 K Index... +19.6
|
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 -55.6 -68.1 275 21 11 1.0 0.5 | -55.9 -68.6 275 23 12 1.0 0.6
45000 -54.1 -65.4 285 28 14 1.2 0.7 | -54.4 -65.9 285 27 14 1.3 0.7
40000 -56.7 -70.1 305 46 23 -1.8 -1.0 | -56.8 -70.2 310 45 23 -1.7 -1.0
38000 -56.8 -70.2 310 51 26 2.4 1.3 | -57.0 -70.6 315 51 26 2.0 1.1
36000 -55.4 -67.7 310 52 27 2.3 1.3 | -55.8 -68.4 320 55 28 2.0 1.1
34000 -53.9 -65.0 315 53 27 4.4 2.4 | -54.5 -66.1 320 59 30 4.9 2.7
32000 -50.6 -59.1 325 56 29 5.7 3.1 | -50.8 -59.4 325 59 30 6.2 3.4
30000 -46.6 -51.9 330 60 31 7.6 4.2 | -47.1 -52.8 325 59 30 6.9 3.8
29000 -44.3 -47.7 330 62 32 7.5 4.1 | -44.5 -48.1 330 59 31 7.0 3.8
28000 -42.1 -43.8 330 64 33 7.5 4.1 | -42.4 -44.3 330 60 31 7.0 3.8
27000 -39.8 -39.6 335 65 34 7.4 4.1 | -40.3 -40.5 330 60 31 7.3 4.0
26000 -37.7 -35.9 335 63 32 7.0 3.8 | -37.9 -36.2 335 60 31 8.0 4.4
25000 -35.6 -32.1 335 60 31 7.0 3.8 | -35.5 -31.9 335 60 31 8.0 4.4
24000 -33.5 -28.3 335 57 29 6.9 3.8 | -33.1 -27.6 335 59 31 8.0 4.4
23000 -31.1 -24.0 335 54 28 8.3 4.6 | -30.6 -23.1 335 57 29 8.5 4.7
22000 -28.7 -19.7 330 51 26 8.3 4.5 | -28.1 -18.6 330 54 28 8.5 4.7
21000 -26.2 -15.2 330 48 25 6.5 3.6 | -25.5 -13.9 330 50 26 7.1 3.9
20000 -24.9 -12.8 325 43 22 4.3 2.3 | -23.7 -10.7 330 47 24 6.0 3.3
19500 -24.3 -11.7 325 41 21 4.3 2.4 | -22.8 -9.0 330 45 23 6.0 3.3
19000 -23.6 -10.5 325 39 20 4.4 2.4 | -21.9 -7.4 330 43 22 6.0 3.3
18500 -23.0 -9.4 320 37 19 4.8 2.6 | -21.0 -5.8 325 41 21 5.3 2.9
18000 -22.2 -8.0 320 35 18 5.8 3.2 | -20.4 -4.7 325 39 20 4.2 2.3
17500 -21.4 -6.5 315 33 17 5.5 3.0 | -19.8 -3.6 325 37 19 4.3 2.4
17000 -19.7 -3.5 315 30 15 8.6 4.7 | -19.2 -2.6 320 35 18 3.5 1.9
16500 -18.5 -1.3 310 27 14 8.6 4.7 | -18.7 -1.7 315 33 17 3.6 2.0
16000 -17.2 1.0 310 25 13 9.1 5.0 | -18.0 -0.4 315 32 16 7.3 4.0
15500 -15.9 3.4 305 23 12 9.3 5.1 | -16.8 1.8 310 29 15 8.5 4.7
15000 -14.6 5.7 300 22 11 7.6 4.2 | -14.9 5.2 310 27 14 8.4 4.6
14500 -13.5 7.7 295 21 11 7.6 4.2 | -13.7 7.3 310 26 13 8.4 4.6
14000 -12.4 9.7 290 19 10 6.8 3.7 | -12.5 9.5 315 25 13 8.5 4.7
13500 -11.5 11.3 290 17 9 6.6 3.6 | -11.3 11.7 315 24 13 8.6 4.7
13000 -10.5 13.1 285 15 8 7.0 3.8 | -10.0 14.0 315 24 12 8.1 4.5
12500 -9.5 14.9 285 12 6 7.2 4.0 | -8.9 16.0 320 23 12 8.0 4.4
12000 -8.4 16.9 280 10 5 7.8 4.3 | -7.7 18.1 320 23 12 7.6 4.2
11500 -7.2 19.0 290 9 4 8.1 4.4 | -6.6 20.1 320 22 11 7.5 4.1
11000 -6.1 21.0 305 8 4 7.5 4.1 | -5.6 21.9 325 21 11 6.6 3.6
10500 -5.0 23.0 325 7 4 7.7 4.2 | -4.6 23.7 325 19 10 6.8 3.7
10250 -4.5 23.9 335 7 4 5.3 2.9 | -4.2 24.4 325 19 10 4.8 2.6
10000 -4.2 24.4 340 7 4 4.4 2.4 | -3.9 25.0 325 18 9 5.2 2.9
9750 -3.8 25.2 350 8 4 7.0 3.8 | -3.3 26.1 330 17 9 8.1 4.5
9500 -3.3 26.1 360 9 5 7.0 3.9 | -2.7 27.1 330 16 8 8.6 4.7
9250 -2.8 27.0 005 10 5 7.0 3.9 | -2.1 28.2 335 15 7 6.9 3.8
9000 -2.2 28.0 010 11 6 7.2 4.0 | -1.7 28.9 335 14 7 5.2 2.9
8750 -1.7 28.9 010 13 7 7.8 4.3 | -1.3 29.7 340 13 7 6.5 3.6
8500 -1.1 30.0 015 14 7 8.0 4.4 | -0.8 30.6 345 13 6 6.8 3.7
8250 -0.5 31.1 015 15 8 8.4 4.6 | -0.3 31.5 350 12 6 6.1 3.3
8000 0.2 32.4 015 16 8 8.8 4.9 | 0.1 32.2 350 12 6 5.7 3.1
7750 0.8 33.4 015 17 9 7.4 4.1 | 0.5 32.9 355 11 6 6.2 3.4
7500 1.3 34.3 015 18 9 7.3 4.0 | 1.0 33.8 355 11 6 7.1 3.9
7250 1.9 35.4 010 18 9 8.6 4.7 | 1.5 34.7 360 10 5 7.6 4.2
7000 2.5 36.5 010 19 10 9.2 5.1 | 2.1 35.8 360 9 5 7.9 4.3
6750 3.2 37.8 005 19 10 7.5 4.1 | 2.7 36.9 005 9 4 7.1 3.9
6500 3.7 38.7 005 19 10 8.9 4.9 | 3.2 37.8 010 7 4 8.8 4.8
6250 4.5 40.1 360 18 9 11.6 6.4 | 4.0 39.2 005 7 4 11.0 6.0
6000 5.4 41.7 360 18 9 10.8 5.9 | 4.8 40.6 005 7 4 10.0 5.5
5750 6.2 43.2 360 17 9 11.2 6.2 | 5.6 42.1 005 6 3 13.5 7.4
5500 7.0 44.6 360 16 8 12.9 7.1 | 6.8 44.2 005 6 3 19.5 10.7
________________________________________________________________________________
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.
042613
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- Page last modified: Sep 19th, 2023 19:10 UTC