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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 161339
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0738 MDT Tuesday, April 16, 2024
This forecast is for Tuesday, April 16, 2024:
If the trigger temperature of 51.3 F/10.7 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 414 ft/min (2.1 m/s)
Maximum height of thermals.................. 15737 ft MSL (10404 ft AGL)
Forecast maximum temperature................... 66.0 F/19.3 C
Time of trigger temperature.................... 0845 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 12839 ft MSL (7506 ft AGL)
Thermal soaring outlook for Wednesday 04/17.... Fair
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)................ Neither
Potential height of wave....................... 14435 ft MSL (9102 ft AGL)
Wave soaring outlook for Wednesday 04/17....... Good
Remarks...
Sunrise/Sunset.................... 06:19:07 / 19:39:03 MDT
Total possible sunshine........... 13 hr 19 min 56 sec (799 min 56 sec)
Altitude of sun at 12:59:05 MDT... 60.73 degrees
Upper air data from numerical model forecast valid on 04/16/2024 at 0600 MDT
Freezing level.................. 8543 ft MSL (3210 ft AGL)
Convective condensation level... 9963 ft MSL (4630 ft AGL)
Lifted condensation level....... 12917 ft MSL (7584 ft AGL)
Lifted index.................... -3.5
K index......................... +24.6
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 -53.4 -64.1 255 31 16 1.3 0.7 M M M M M
45000 -51.4 -60.5 260 30 15 1.3 0.7 M M M M M
40000 -49.4 -56.9 285 33 17 1.3 0.7 M M M M M
38000 -48.5 -55.3 290 32 17 1.6 0.9 M M M M M
36000 -47.5 -53.5 295 27 14 1.6 0.9 M M M M M
34000 -46.6 -51.9 300 22 11 1.1 0.6 M M M M M
32000 -47.0 -52.6 335 35 18 -0.7 -0.4 M M M M M
30000 -47.1 -52.8 350 51 26 7.3 4.0 28.2 82.7 7.0 M M
29000 -44.4 -47.9 345 50 26 8.8 4.8 27.7 81.8 6.7 M M
28000 -41.8 -43.2 345 50 26 8.9 4.9 27.3 81.1 6.5 M M
27000 -39.2 -38.6 340 50 26 8.9 4.9 27.1 80.7 6.3 M M
26000 -36.6 -33.9 340 49 25 8.3 4.5 26.5 79.8 6.0 M M
25000 -34.2 -29.6 340 47 24 8.3 4.5 25.9 78.7 5.6 M M
24000 -31.7 -25.1 345 45 23 8.3 4.5 25.5 77.8 5.2 M M
23000 -29.3 -20.7 345 44 22 8.1 4.5 24.9 76.8 4.8 M M
22000 -26.9 -16.4 345 42 22 8.1 4.5 24.2 75.6 4.3 M M
21000 -24.4 -11.9 345 41 21 8.2 4.5 23.7 74.7 3.9 M M
20000 -22.1 -7.8 345 40 21 7.6 4.2 23.0 73.4 3.3 M M
19500 -21.0 -5.8 345 40 21 7.6 4.2 22.6 72.7 3.0 M M
19000 -19.9 -3.8 345 40 21 7.6 4.2 22.2 72.0 2.6 M M
18500 -18.8 -1.8 345 40 21 7.7 4.2 21.9 71.4 2.4 M M
18000 -17.1 1.2 345 40 21 7.1 3.9 21.3 70.4 1.8 M M
17500 -16.1 3.0 345 40 21 7.2 3.9 20.9 69.5 1.4 M M
17000 -15.0 5.0 345 41 21 7.0 3.8 20.4 68.7 1.0 M M
16500 -14.0 6.8 345 41 21 7.0 3.8 19.9 67.9 0.6 M M
16000 -13.0 8.6 345 42 22 7.0 3.8 19.5 67.1 0.2 M M
15500 -12.0 10.4 345 43 22 7.0 3.8 19.0 66.2 -0.3 785 4.0
15000 -11.0 12.2 345 44 23 7.0 3.8 18.6 65.4 -0.7 739 3.8
14500 -10.0 14.0 345 45 23 6.7 3.7 18.1 64.5 -1.2 695 3.5
14000 -9.0 15.8 345 47 24 6.8 3.7 17.5 63.6 -1.7 651 3.3
13500 -8.1 17.4 345 48 25 6.0 3.3 17.0 62.6 -2.3 609 3.1
13000 -7.2 19.0 345 49 25 6.1 3.3 16.4 61.5 -2.9 568 2.9
12500 -6.3 20.7 340 49 25 5.8 3.2 15.8 60.4 -3.5 527 2.7
12000 -5.5 22.1 340 49 25 5.8 3.2 15.1 59.3 -4.1 487 2.5
11500 -4.6 23.7 340 48 25 6.0 3.3 14.5 58.1 -4.7 447 2.3
11000 -3.8 25.2 335 47 24 6.1 3.3 13.9 57.0 -5.4 406 2.1
10500 -3.0 26.6 335 45 23 4.7 2.6 13.2 55.8 -6.1 367 1.9
10250 -2.6 27.3 335 45 23 4.5 2.5 12.8 55.1 -6.5 350 1.8
10000 -2.3 27.9 330 45 23 5.8 3.2 12.5 54.4 -6.9 332 1.7
9750 -1.8 28.8 330 43 22 5.7 3.1 12.2 53.9 -7.1 311 1.6
9500 -1.5 29.3 330 42 22 4.6 2.5 11.8 53.2 -7.5 293 1.5
9250 -1.1 30.0 330 41 21 4.4 2.4 11.4 52.5 -8.0 275 1.4
9000 -0.8 30.6 325 41 21 5.5 3.0 11.0 51.8 -8.4 258 1.3
8750 -0.4 31.3 325 39 20 5.8 3.2 10.7 51.3 -8.7 237 1.2
8500 0.0 32.0 325 37 19 4.8 2.6 10.4 50.6 -9.0 218 1.1
8250 0.4 32.7 320 36 18 5.5 3.0 10.0 50.0 -9.4 200 1.0
8000 0.8 33.4 320 34 18 3.9 2.2 9.6 49.4 -9.8 181 0.9
7750 1.0 33.8 320 33 17 5.9 3.2 9.2 48.5 -10.3 165 0.8
7500 1.6 34.9 320 31 16 8.4 4.6 9.1 48.3 -10.4 140 0.7
7250 2.2 36.0 315 29 15 8.7 4.8 8.9 48.1 -10.6 115 0.6
7000 2.8 37.0 315 28 14 4.7 2.6 8.8 47.8 -10.8 90 0.5
6750 3.1 37.6 315 27 14 5.4 3.0 8.3 46.9 -11.3 76 0.4
6500 3.7 38.7 315 24 12 10.5 5.7 8.2 46.8 -11.4 48 0.2
6250 4.4 39.9 310 21 11 8.5 4.7 8.2 46.8 -11.4 20 0.1
6000 5.0 41.0 310 19 10 6.6 3.6 8.1 46.5 -11.6 M M
5750 5.4 41.7 310 16 8 6.9 3.8 7.8 46.0 -11.9 M M
5500 6.1 43.0 305 13 7 10.8 5.9 7.7 45.9 -12.1 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/16/2024 at 0900 MDT | 04/16/2024 at 1200 MDT
|
CAPE... +55.5 LI... +1.0 | CAPE... +58.3 LI... +1.2
CINH... -5.2 K Index... +20.9 | CINH... -0.5 K Index... +18.6
|
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 -54.4 -65.9 255 30 16 1.2 0.7 | -55.0 -67.0 255 34 18 1.1 0.6
45000 -52.5 -62.5 265 35 18 1.7 0.9 | -53.3 -63.9 270 38 19 1.5 0.8
40000 -49.8 -57.6 280 31 16 1.8 1.0 | -50.9 -59.6 270 29 15 1.6 0.9
38000 -49.5 -57.1 290 31 16 -1.0 -0.5 | -50.9 -59.6 275 27 14 -1.9 -1.1
36000 -50.0 -58.0 300 34 17 -1.0 -0.5 | -52.1 -61.8 290 27 14 -1.9 -1.1
34000 -50.6 -59.1 305 37 19 1.2 0.7 | -53.0 -63.4 300 27 14 3.6 2.0
32000 -48.4 -55.1 325 41 21 3.3 1.8 | -49.0 -56.2 305 29 15 5.9 3.2
30000 -46.0 -50.8 335 46 24 9.2 5.0 | -45.2 -49.4 310 31 16 8.6 4.7
29000 -43.4 -46.1 335 46 23 8.6 4.7 | -42.6 -44.7 310 33 17 8.6 4.7
28000 -40.8 -41.4 335 45 23 8.6 4.7 | -40.1 -40.2 305 34 18 8.6 4.7
27000 -38.3 -36.9 335 45 23 8.6 4.7 | -37.5 -35.5 305 36 19 8.5 4.7
26000 -35.7 -32.3 335 46 23 8.5 4.7 | -35.0 -31.0 305 35 18 8.5 4.6
25000 -33.2 -27.8 335 47 24 8.5 4.7 | -32.4 -26.3 310 34 18 8.5 4.6
24000 -30.6 -23.1 340 48 25 8.6 4.7 | -29.9 -21.8 310 33 17 8.5 4.7
23000 -28.2 -18.8 340 48 25 7.9 4.3 | -27.5 -17.5 315 33 17 7.8 4.3
22000 -25.9 -14.6 340 48 25 7.9 4.3 | -25.2 -13.4 320 33 17 7.8 4.3
21000 -23.5 -10.3 345 49 25 7.7 4.2 | -22.9 -9.2 320 34 17 7.5 4.1
20000 -21.5 -6.7 345 50 26 6.5 3.6 | -20.8 -5.4 325 35 18 6.9 3.8
19500 -20.6 -5.1 340 51 26 6.5 3.6 | -19.8 -3.6 325 35 18 6.9 3.8
19000 -19.6 -3.3 340 52 27 6.5 3.6 | -18.7 -1.7 325 36 18 6.9 3.8
18500 -18.6 -1.5 340 53 27 6.6 3.6 | -17.7 0.1 325 36 19 6.8 3.8
18000 -17.7 0.1 340 53 27 6.3 3.4 | -16.8 1.8 330 37 19 6.0 3.3
17500 -16.8 1.8 340 53 27 6.3 3.5 | -15.4 4.3 330 38 20 6.1 3.3
17000 -15.8 3.6 340 53 27 6.5 3.6 | -14.5 5.9 330 39 20 6.2 3.4
16500 -14.8 5.4 340 53 27 6.7 3.7 | -13.6 7.5 330 39 20 6.2 3.4
16000 -13.4 7.9 340 52 27 6.7 3.7 | -12.7 9.1 330 39 20 6.2 3.4
15500 -12.4 9.7 340 52 27 6.7 3.7 | -11.8 10.8 330 39 20 6.2 3.4
15000 -11.4 11.5 340 52 27 6.9 3.8 | -11.0 12.2 330 39 20 6.4 3.5
14500 -10.4 13.3 340 52 27 7.2 3.9 | -10.0 14.0 330 38 20 6.6 3.6
14000 -9.3 15.3 340 52 27 7.2 4.0 | -9.1 15.6 325 37 19 6.8 3.7
13500 -8.2 17.2 340 51 26 7.5 4.1 | -8.0 17.6 325 37 19 7.1 3.9
13000 -7.1 19.2 340 49 25 7.6 4.1 | -7.0 19.4 325 36 18 7.3 4.0
12500 -6.0 21.2 340 48 25 7.7 4.2 | -5.9 21.4 325 35 18 7.8 4.3
12000 -4.9 23.2 335 47 24 7.7 4.2 | -4.7 23.5 325 34 18 7.9 4.3
11500 -3.8 25.2 335 47 24 7.7 4.2 | -3.5 25.7 325 33 17 8.3 4.5
11000 -2.6 27.3 335 46 24 7.6 4.2 | -2.3 27.9 320 31 16 8.1 4.4
10500 -1.6 29.1 335 45 23 6.1 3.3 | -1.2 29.8 320 29 15 7.1 3.9
10250 -1.1 30.0 335 45 23 7.1 3.9 | -0.6 30.9 320 28 14 9.1 5.0
10000 -0.5 31.1 330 44 23 10.4 5.7 | 0.2 32.4 320 28 14 11.9 6.5
9750 0.3 32.5 330 43 22 9.4 5.2 | 1.0 33.8 320 28 14 10.2 5.6
9500 0.9 33.6 330 41 21 7.3 4.0 | 1.7 35.1 320 27 14 9.1 5.0
9250 1.4 34.5 330 40 21 7.4 4.1 | 2.4 36.3 320 27 14 9.0 4.9
9000 2.0 35.6 325 39 20 9.0 4.9 | 3.1 37.6 320 26 13 10.5 5.8
8750 2.7 36.9 325 38 19 9.1 5.0 | 3.9 39.0 320 27 14 10.7 5.9
8500 3.3 37.9 325 36 19 7.3 4.0 | 4.6 40.3 320 27 14 9.3 5.1
8250 3.9 39.0 320 35 18 8.1 4.4 | 5.3 41.5 320 26 14 9.6 5.3
8000 4.5 40.1 320 34 17 6.8 3.7 | 6.0 42.8 320 26 13 9.2 5.1
7750 4.9 40.8 320 32 16 6.8 3.7 | 6.7 44.1 320 25 13 9.6 5.3
7500 5.5 41.9 315 30 16 8.1 4.4 | 7.5 45.5 320 25 13 10.3 5.6
7250 6.1 43.0 315 29 15 7.3 4.0 | 8.2 46.8 320 25 13 9.5 5.2
7000 6.5 43.7 315 27 14 5.2 2.9 | 8.9 48.0 320 25 13 8.2 4.5
6750 6.9 44.4 310 26 13 6.1 3.4 | 9.5 49.1 320 25 13 10.3 5.6
6500 7.5 45.5 310 23 12 8.5 4.7 | 10.4 50.7 320 24 12 12.2 6.7
6250 8.0 46.4 310 20 10 6.6 3.6 | 11.3 52.3 320 23 12 10.7 5.9
6000 8.4 47.1 305 18 9 4.8 2.6 | 12.0 53.6 320 23 12 10.0 5.5
5750 8.7 47.7 305 15 8 6.5 3.6 | 12.8 55.0 320 22 11 10.3 5.7
5500 9.3 48.7 300 11 6 10.0 5.5 | 13.7 56.7 320 20 10 15.5 8.5
04/16/2024 at 1500 MDT | 04/16/2024 at 1800 MDT
|
CAPE... +31.2 LI... +1.1 | CAPE... 0.0 LI... +1.6
CINH... -1.4 K Index... +18.3 | CINH... 0.0 K Index... +11.3
|
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 -55.1 -67.2 260 35 18 1.2 0.7 | -55.8 -68.4 260 39 20 1.5 0.8
45000 -53.3 -63.9 260 38 20 1.1 0.6 | -53.6 -64.5 260 44 23 1.5 0.8
40000 -51.7 -61.1 265 33 17 1.1 0.6 | -51.3 -60.3 265 33 17 1.5 0.8
38000 -51.7 -61.1 270 31 16 -1.2 -0.6 | -51.4 -60.5 270 31 16 -1.8 -1.0
36000 -52.4 -62.3 275 29 15 -1.2 -0.6 | -52.5 -62.5 280 31 16 -1.8 -1.0
34000 -52.3 -62.1 285 28 15 6.2 3.4 | -52.7 -62.9 290 31 16 6.2 3.4
32000 -48.8 -55.8 285 28 14 5.9 3.3 | -49.0 -56.2 295 31 16 6.1 3.4
30000 -44.9 -48.8 285 28 14 8.2 4.5 | -45.0 -49.0 300 31 16 8.0 4.4
29000 -42.5 -44.5 285 28 14 8.2 4.5 | -42.6 -44.7 300 32 16 8.0 4.4
28000 -40.0 -40.0 285 28 15 8.2 4.5 | -40.2 -40.4 305 32 17 8.0 4.4
27000 -37.6 -35.7 285 29 15 8.1 4.4 | -37.8 -36.0 305 33 17 8.0 4.4
26000 -35.2 -31.4 285 28 15 7.9 4.3 | -35.4 -31.7 305 32 17 8.1 4.4
25000 -32.8 -27.0 290 28 14 7.9 4.3 | -33.0 -27.4 305 32 16 8.1 4.4
24000 -30.4 -22.7 290 28 14 7.9 4.3 | -30.6 -23.1 305 31 16 8.1 4.4
23000 -28.0 -18.4 295 27 14 8.1 4.5 | -28.1 -18.6 310 30 15 8.2 4.5
22000 -25.6 -14.1 295 26 14 8.1 4.5 | -25.6 -14.1 310 29 15 8.2 4.5
21000 -23.2 -9.8 300 26 13 7.9 4.3 | -23.2 -9.8 315 28 14 8.1 4.5
20000 -20.9 -5.6 305 26 13 7.6 4.2 | -20.8 -5.4 315 27 14 8.1 4.4
19500 -19.8 -3.6 310 26 14 7.6 4.2 | -19.6 -3.3 315 27 14 8.1 4.4
19000 -18.6 -1.5 310 27 14 7.6 4.2 | -17.8 -0.0 320 26 14 8.1 4.5
18500 -17.0 1.4 315 27 14 6.9 3.8 | -16.6 2.1 320 26 13 7.6 4.2
18000 -16.0 3.2 315 28 14 6.8 3.7 | -15.5 4.1 320 25 13 7.6 4.2
17500 -15.0 5.0 320 28 14 6.7 3.7 | -14.3 6.3 325 25 13 7.4 4.0
17000 -14.0 6.8 320 28 14 6.3 3.5 | -13.3 8.1 325 25 13 7.0 3.8
16500 -13.1 8.4 320 28 14 6.3 3.5 | -12.3 9.9 325 24 13 7.0 3.8
16000 -12.2 10.0 320 28 14 6.9 3.8 | -11.2 11.8 325 24 12 7.1 3.9
15500 -11.2 11.8 320 28 14 6.9 3.8 | -10.2 13.6 325 23 12 7.1 3.9
15000 -10.2 13.6 315 28 14 6.8 3.8 | -9.1 15.6 325 23 12 7.2 3.9
14500 -9.2 15.4 315 28 14 6.9 3.8 | -8.1 17.4 325 22 11 7.2 3.9
14000 -8.2 17.2 315 28 14 7.1 3.9 | -7.0 19.4 325 21 11 7.5 4.1
13500 -7.1 19.2 315 27 14 7.4 4.0 | -5.9 21.4 325 21 11 7.7 4.2
13000 -6.0 21.2 315 26 14 7.8 4.3 | -4.7 23.5 325 20 10 7.9 4.4
12500 -4.8 23.4 310 26 13 8.4 4.6 | -3.5 25.7 325 20 10 8.2 4.5
12000 -3.6 25.5 310 26 13 8.6 4.7 | -2.3 27.9 320 20 10 8.3 4.6
11500 -2.2 28.0 310 26 13 9.1 5.0 | -1.1 30.0 320 20 11 8.4 4.6
11000 -0.9 30.4 310 26 13 8.6 4.7 | 0.2 32.4 315 22 11 7.6 4.2
10500 0.3 32.5 310 25 13 6.9 3.8 | 1.1 34.0 310 22 11 5.8 3.2
10250 0.8 33.4 310 25 13 10.4 5.7 | 1.6 34.9 310 22 12 9.4 5.2
10000 1.8 35.2 310 26 13 12.6 6.9 | 2.5 36.5 305 24 12 11.0 6.0
9750 2.6 36.7 305 26 13 9.6 5.3 | 3.1 37.6 305 24 12 8.2 4.5
9500 3.3 37.9 305 26 13 9.7 5.3 | 3.7 38.7 305 24 12 9.0 4.9
9250 4.0 39.2 305 26 13 9.0 4.9 | 4.4 39.9 305 24 12 7.8 4.3
9000 4.6 40.3 305 25 13 8.9 4.9 | 4.9 40.8 305 23 12 8.1 4.5
8750 5.4 41.7 305 25 13 10.1 5.5 | 5.6 42.1 305 24 12 9.7 5.3
8500 6.1 43.0 305 25 13 10.4 5.7 | 6.3 43.3 300 24 12 9.7 5.3
8250 6.9 44.4 305 25 13 9.9 5.4 | 7.0 44.6 300 24 12 9.2 5.1
8000 7.6 45.7 305 25 13 9.2 5.0 | 7.7 45.9 300 24 12 8.5 4.7
7750 8.3 46.9 305 25 13 9.8 5.4 | 8.3 46.9 300 24 12 9.3 5.1
7500 9.1 48.4 305 25 13 10.9 6.0 | 9.1 48.4 300 24 12 10.1 5.6
7250 9.9 49.8 305 25 13 9.3 5.1 | 9.8 49.6 300 24 12 9.0 4.9
7000 10.5 50.9 305 25 13 7.6 4.1 | 10.4 50.7 300 24 12 7.9 4.4
6750 11.1 52.0 305 24 13 10.4 5.7 | 11.1 52.0 300 23 12 10.3 5.7
6500 12.0 53.6 305 24 12 12.4 6.8 | 11.9 53.4 300 23 12 11.7 6.4
6250 12.9 55.2 305 23 12 10.9 6.0 | 12.7 54.9 300 22 11 10.2 5.6
6000 13.7 56.7 305 23 12 10.5 5.8 | 13.5 56.3 300 21 11 9.7 5.3
5750 14.5 58.1 305 22 11 10.4 5.7 | 14.2 57.6 300 20 10 9.8 5.4
5500 15.4 59.7 305 20 10 16.4 9.0 | 15.0 59.0 300 18 9 12.2 6.7
________________________________________________________________________________
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
- National Weather Service
- Central Illinois Weather Forecast Office
- 1362 State Route 10
- Lincoln, IL 62656
- 217-732-7321 (forecast recording) or 217-732-3089
- Page Author: ILX Webmaster
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- Page last modified: Sep 19th, 2023 19:10 UTC