Soaring Guidance Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 271341
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0739 MDT Wednesday, March 27, 2024
This forecast is for Wednesday, March 27, 2024:
If the trigger temperature of 42.1 F/5.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1502 ft/min (7.6 m/s)
Maximum height of thermals.................. 20705 ft MSL (15379 ft AGL)
Forecast maximum temperature................... 51.0 F/11.0 C
Time of trigger temperature.................... 1030 MDT
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................. 13475 ft MSL (8150 ft AGL)
Thermal soaring outlook for Thursday 03/28..... 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)................ Weak NVA
Potential height of wave....................... 24056 ft MSL (18730 ft AGL)
Wave soaring outlook for Thursday 03/28........ Poor
Remarks...
Sunrise/Sunset.................... 06:50:11 / 19:18:58 MDT
Total possible sunshine........... 12 hr 28 min 48 sec (748 min 48 sec)
Altitude of sun at 13:04:35 MDT... 53.23 degrees
Upper air data from numerical model forecast valid on 03/27/2024 at 0600 MDT
Freezing level.................. 5552 ft MSL (226 ft AGL)
Additional freezing level....... 6655 ft MSL (1329 ft AGL)
Convective condensation level... 13083 ft MSL (7757 ft AGL)
Lifted condensation level....... 14504 ft MSL (9178 ft AGL)
Lifted index.................... -2.5
K index......................... +14.6
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 -53.2 -63.8 290 37 19 1.3 0.7 M M M M M
45000 -51.3 -60.3 295 37 19 1.3 0.7 M M M M M
40000 -51.1 -60.0 300 42 21 -0.2 -0.1 M M M M M
38000 -51.2 -60.2 300 44 23 -0.2 -0.1 M M M M M
36000 -52.6 -62.7 305 39 20 -2.3 -1.2 M M M M M
34000 -54.0 -65.2 305 33 17 -2.3 -1.3 M M M M M
32000 -53.8 -64.8 295 29 15 1.6 0.9 M M M M M
30000 -52.9 -63.2 285 26 14 1.7 0.9 M M M M M
29000 -52.1 -61.8 275 25 13 4.1 2.2 21.0 69.9 7.9 M M
28000 -50.9 -59.6 270 24 12 4.0 2.2 18.6 65.5 6.1 M M
27000 -49.7 -57.5 265 22 11 4.0 2.2 16.4 61.5 4.5 M M
26000 -48.5 -55.3 265 21 11 6.0 3.3 14.4 57.9 3.0 M M
25000 -46.3 -51.3 270 21 11 7.1 3.9 13.2 55.8 2.1 M M
24000 -44.2 -47.6 275 22 11 7.1 3.9 12.2 54.0 1.3 M M
23000 -42.0 -43.6 280 23 12 8.4 4.6 11.4 52.6 0.7 M M
22000 -39.4 -38.9 285 22 11 8.8 4.8 11.0 51.8 0.3 M M
21000 -36.7 -34.1 290 21 11 8.8 4.8 10.7 51.2 0.1 M M
20000 -34.1 -29.4 295 21 11 8.7 4.8 10.4 50.7 -0.2 1437 7.3
19500 -32.8 -27.0 300 21 11 8.8 4.8 10.2 50.3 -0.4 1383 7.0
19000 -30.8 -23.4 300 20 11 8.8 4.8 9.9 49.8 -0.6 1302 6.6
18500 -29.5 -21.1 300 20 10 8.8 4.8 9.8 49.6 -0.7 1248 6.3
18000 -28.2 -18.8 305 20 10 8.6 4.7 9.6 49.3 -0.9 1194 6.1
17500 -27.0 -16.6 305 20 10 8.5 4.7 9.4 48.9 -1.1 1141 5.8
17000 -25.7 -14.3 305 20 10 8.4 4.6 9.2 48.6 -1.3 1088 5.5
16500 -24.4 -11.9 305 19 10 8.3 4.6 8.9 48.1 -1.5 1036 5.3
16000 -23.2 -9.8 305 19 10 8.3 4.5 8.7 47.7 -1.8 985 5.0
15500 -22.0 -7.6 305 18 9 8.2 4.5 8.4 47.2 -2.0 933 4.7
15000 -20.8 -5.4 305 18 9 8.2 4.5 8.2 46.7 -2.3 882 4.5
14500 -19.5 -3.1 305 17 9 8.3 4.5 7.9 46.3 -2.5 830 4.2
14000 -18.3 -0.9 305 17 9 8.3 4.5 7.7 45.8 -2.8 778 4.0
13500 -17.0 1.4 305 17 9 8.4 4.6 7.5 45.4 -3.0 726 3.7
13000 -15.8 3.6 305 17 9 8.4 4.6 7.2 45.0 -3.2 673 3.4
12500 -14.5 5.9 305 17 9 8.6 4.7 7.0 44.7 -3.5 621 3.2
12000 -13.3 8.1 305 17 9 8.6 4.7 6.8 44.3 -3.7 568 2.9
11500 -12.0 10.4 305 17 9 8.7 4.8 6.7 44.0 -3.9 514 2.6
11000 -10.7 12.7 310 17 8 8.8 4.9 6.5 43.7 -4.1 461 2.3
10500 -9.5 14.9 310 16 8 7.2 3.9 6.2 43.1 -4.4 411 2.1
10250 -9.0 15.8 310 16 8 6.1 3.4 6.0 42.7 -4.6 388 2.0
10000 -8.4 16.9 310 17 8 11.0 6.0 5.8 42.4 -4.8 364 1.9
9750 -7.4 18.7 305 17 9 11.9 6.5 6.1 42.9 -4.5 326 1.7
9500 -6.8 19.8 305 17 9 7.5 4.1 6.0 42.7 -4.6 300 1.5
9250 -6.2 20.8 305 17 9 9.1 5.0 5.9 42.6 -4.7 274 1.4
9000 -5.5 22.1 305 18 9 7.1 3.9 5.8 42.4 -4.9 247 1.3
8750 -5.0 23.0 305 18 9 7.5 4.1 5.5 41.9 -5.1 225 1.1
8500 -4.4 24.1 305 19 10 9.2 5.1 5.4 41.8 -5.2 198 1.0
8250 -3.7 25.3 305 19 10 8.9 4.9 5.4 41.7 -5.3 171 0.9
8000 -3.1 26.4 305 19 10 7.7 4.2 5.3 41.6 -5.4 144 0.7
7750 -2.5 27.5 305 20 10 7.6 4.1 5.1 41.2 -5.6 121 0.6
7500 -1.9 28.6 305 19 10 8.9 4.9 5.0 41.0 -5.7 94 0.5
7250 -1.3 29.7 300 18 9 7.8 4.3 4.9 40.8 -5.8 68 0.3
7000 -0.8 30.6 300 17 9 6.0 3.3 4.7 40.4 -6.1 45 0.2
6750 -0.3 31.5 305 16 8 6.6 3.6 4.4 39.9 -6.4 25 0.1
6500 0.2 32.4 300 14 7 7.3 4.0 4.2 39.6 -6.6 1 0.0
6250 0.6 33.1 300 11 6 1.8 1.0 3.9 39.0 -7.0 M M
6000 0.5 32.9 300 9 5 -1.9 -1.1 3.1 37.5 -7.8 M M
5750 0.4 32.7 295 8 4 -0.1 -0.0 2.2 36.0 -8.7 M M
5500 0.2 32.4 275 6 3 -8.3 -4.6 1.3 34.4 -9.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
03/27/2024 at 0900 MDT | 03/27/2024 at 1200 MDT
|
CAPE... +1.7 LI... +1.5 | CAPE... +37.3 LI... +0.7
CINH... -6.1 K Index... +9.7 | CINH... -5.9 K Index... +6.8
|
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 -53.4 -64.1 290 34 18 1.0 0.5 | -54.4 -65.9 285 36 18 0.5 0.3
45000 -52.0 -61.6 300 40 21 1.0 0.5 | -53.6 -64.5 300 46 24 0.5 0.3
40000 -52.1 -61.8 310 46 24 -0.3 -0.2 | -54.0 -65.2 315 54 28 -0.4 -0.2
38000 -52.4 -62.3 315 49 25 -1.0 -0.6 | -54.2 -65.6 320 58 30 -0.3 -0.2
36000 -53.2 -63.8 320 47 24 -1.4 -0.8 | -54.4 -65.9 325 64 33 -0.3 -0.2
34000 -54.0 -65.2 320 44 23 -1.4 -0.8 | -54.6 -66.3 325 70 36 -0.2 -0.1
32000 -53.3 -63.9 330 40 21 2.7 1.5 | -53.4 -64.1 325 65 34 3.0 1.7
30000 -51.7 -61.1 335 36 18 2.7 1.5 | -51.3 -60.3 325 55 28 2.6 1.4
29000 -50.3 -58.5 340 34 17 4.5 2.5 | -49.7 -57.5 325 51 26 6.3 3.4
28000 -49.0 -56.2 340 32 17 4.5 2.5 | -47.8 -54.0 325 47 24 6.2 3.4
27000 -47.6 -53.7 340 31 16 4.5 2.5 | -46.0 -50.8 325 43 22 6.2 3.4
26000 -46.2 -51.2 340 29 15 5.5 3.0 | -44.0 -47.2 325 40 20 7.1 3.9
25000 -44.6 -48.3 325 25 13 5.5 3.0 | -41.9 -43.4 320 36 19 7.0 3.9
24000 -42.9 -45.2 310 23 12 5.4 3.0 | -39.8 -39.6 320 33 17 7.0 3.9
23000 -41.1 -42.0 300 21 11 8.0 4.4 | -37.8 -36.0 320 30 15 6.2 3.4
22000 -38.8 -37.8 295 20 10 7.8 4.3 | -35.9 -32.6 315 27 14 6.3 3.4
21000 -36.5 -33.7 295 19 10 7.8 4.3 | -34.0 -29.2 310 25 13 6.3 3.4
20000 -34.0 -29.2 295 18 9 8.9 4.9 | -32.0 -25.6 305 23 12 7.0 3.8
19500 -32.7 -26.9 295 18 9 8.9 4.9 | -31.0 -23.8 305 22 11 7.0 3.8
19000 -31.4 -24.5 295 18 9 8.9 4.9 | -29.9 -21.8 300 21 11 7.0 3.8
18500 -30.0 -22.0 295 18 9 8.9 4.9 | -28.9 -20.0 300 21 11 7.0 3.8
18000 -28.7 -19.7 295 18 9 8.7 4.8 | -27.8 -18.0 295 20 10 7.4 4.1
17500 -27.4 -17.3 295 18 9 8.5 4.7 | -26.7 -16.1 295 19 10 7.6 4.1
17000 -26.2 -15.2 295 18 9 8.5 4.7 | -25.6 -14.1 290 18 9 7.6 4.2
16500 -24.9 -12.8 300 18 9 8.3 4.5 | -23.8 -10.8 290 17 9 7.7 4.2
16000 -23.1 -9.6 305 17 9 8.2 4.5 | -22.7 -8.9 290 16 8 7.6 4.2
15500 -21.9 -7.4 305 17 9 8.2 4.5 | -21.6 -6.9 295 15 8 7.6 4.2
15000 -20.6 -5.1 310 17 9 8.1 4.5 | -20.4 -4.7 300 14 7 7.7 4.2
14500 -19.4 -2.9 310 17 9 8.0 4.4 | -19.3 -2.7 305 14 7 8.0 4.4
14000 -18.3 -0.9 315 17 9 8.1 4.4 | -18.1 -0.6 310 14 7 8.0 4.4
13500 -17.0 1.4 315 18 9 8.3 4.6 | -16.9 1.6 310 15 8 8.4 4.6
13000 -15.8 3.6 315 18 9 8.3 4.6 | -15.6 3.9 310 16 8 8.5 4.6
12500 -14.6 5.7 315 19 10 8.0 4.4 | -14.3 6.3 305 16 8 8.9 4.9
12000 -13.4 7.9 315 19 10 8.1 4.4 | -13.0 8.6 305 16 8 8.9 4.9
11500 -12.2 10.0 315 19 10 8.3 4.5 | -11.7 10.9 305 16 8 9.1 5.0
11000 -11.0 12.2 315 20 10 8.2 4.5 | -10.3 13.5 305 16 8 9.0 4.9
10500 -9.8 14.4 315 19 10 7.8 4.3 | -9.0 15.8 305 16 8 8.6 4.7
10250 -9.2 15.4 315 19 10 8.8 4.8 | -8.4 16.9 305 16 8 9.7 5.3
10000 -8.6 16.5 310 19 10 5.1 2.8 | -7.7 18.1 305 16 8 5.6 3.1
9750 -8.3 17.1 315 19 10 6.2 3.4 | -7.4 18.7 305 15 8 6.9 3.8
9500 -7.6 18.3 310 18 9 10.5 5.8 | -6.6 20.1 305 15 8 12.0 6.6
9250 -6.9 19.6 310 18 9 9.9 5.4 | -5.8 21.6 305 15 8 10.3 5.6
9000 -6.2 20.8 310 18 9 7.1 3.9 | -5.1 22.8 305 15 8 7.6 4.1
8750 -5.8 21.6 310 17 9 7.2 3.9 | -4.6 23.7 305 14 7 8.4 4.6
8500 -5.0 23.0 310 17 9 10.4 5.7 | -3.8 25.2 305 14 7 11.4 6.3
8250 -4.3 24.3 310 16 8 9.1 5.0 | -3.0 26.6 305 14 7 9.6 5.2
8000 -3.7 25.3 310 16 8 7.3 4.0 | -2.4 27.7 305 13 7 7.4 4.1
7750 -3.2 26.2 310 15 8 8.3 4.6 | -1.8 28.8 305 12 6 9.5 5.2
7500 -2.4 27.7 305 15 8 10.7 5.9 | -1.0 30.2 305 12 6 11.4 6.3
7250 -1.7 28.9 305 15 8 8.3 4.6 | -0.2 31.6 305 12 6 8.8 4.8
7000 -1.2 29.8 305 14 7 5.8 3.2 | 0.3 32.5 305 11 6 5.9 3.3
6750 -0.7 30.7 305 14 7 8.8 4.8 | 0.9 33.6 305 10 5 10.9 6.0
6500 0.0 32.0 300 13 7 9.1 5.0 | 1.9 35.4 300 10 5 12.9 7.1
6250 0.5 32.9 300 11 6 5.7 3.1 | 2.6 36.7 300 10 5 9.6 5.3
6000 0.9 33.6 295 10 5 5.0 2.7 | 3.4 38.1 300 9 5 9.1 5.0
5750 1.3 34.3 290 8 4 6.1 3.4 | 4.1 39.4 300 8 4 12.2 6.7
5500 1.8 35.2 285 7 4 8.0 4.4 | 5.3 41.5 300 8 4 21.6 11.8
03/27/2024 at 1500 MDT | 03/27/2024 at 1800 MDT
|
CAPE... +73.6 LI... -0.1 | CAPE... +34.5 LI... +2.2
CINH... -6.3 K Index... +11.2 | CINH... -14.8 K Index... +11.1
|
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 -55.0 -67.0 290 42 22 0.5 0.3 | -56.1 -69.0 285 45 23 1.1 0.6
45000 -54.2 -65.6 300 46 23 0.5 0.3 | -54.4 -65.9 295 57 29 1.0 0.5
40000 -56.3 -69.3 310 65 33 -1.7 -0.9 | -59.4 -74.9 310 77 40 -3.9 -2.1
38000 -57.1 -70.8 315 74 38 1.2 0.6 | -60.9 -77.6 315 87 45 4.0 2.2
36000 -56.6 -69.9 320 87 45 0.9 0.5 | -58.7 -73.7 320 98 50 3.6 2.0
34000 -56.0 -68.8 330 101 52 0.7 0.4 | -56.5 -69.7 320 108 56 3.2 1.8
32000 -52.5 -62.5 330 99 51 6.3 3.5 | -51.9 -61.4 320 99 51 7.3 4.0
30000 -48.7 -55.7 330 94 48 6.4 3.5 | -47.5 -53.5 325 88 45 7.0 3.8
29000 -46.7 -52.1 330 87 45 6.6 3.6 | -45.5 -49.9 325 83 43 6.7 3.7
28000 -44.7 -48.5 330 79 41 6.6 3.6 | -43.6 -46.5 325 77 40 6.7 3.7
27000 -42.7 -44.9 330 71 37 6.6 3.6 | -41.6 -42.9 320 72 37 6.6 3.6
26000 -40.8 -41.4 330 64 33 6.3 3.5 | -39.3 -38.7 320 68 35 7.9 4.3
25000 -38.9 -38.0 325 57 29 6.3 3.5 | -37.0 -34.6 325 66 34 7.9 4.3
24000 -37.0 -34.6 325 50 26 6.3 3.5 | -34.6 -30.3 325 64 33 7.9 4.3
23000 -35.2 -31.4 320 43 22 6.0 3.3 | -32.3 -26.1 325 62 32 7.5 4.1
22000 -33.4 -28.1 315 38 19 6.0 3.3 | -30.0 -22.0 325 58 30 7.5 4.1
21000 -31.6 -24.9 310 33 17 6.1 3.3 | -27.8 -18.0 325 55 28 8.0 4.4
20000 -30.0 -22.0 305 29 15 4.9 2.7 | -26.4 -15.5 325 48 25 3.8 2.1
19500 -29.2 -20.6 300 27 14 5.0 2.7 | -25.8 -14.4 325 43 22 3.8 2.1
19000 -28.5 -19.3 300 25 13 5.0 2.7 | -25.2 -13.4 320 39 20 3.8 2.1
18500 -27.8 -18.0 295 24 12 4.9 2.7 | -24.7 -12.5 320 35 18 3.9 2.1
18000 -27.0 -16.6 295 22 11 5.8 3.2 | -24.1 -11.4 315 31 16 3.2 1.8
17500 -26.1 -15.0 290 21 11 6.0 3.3 | -23.7 -10.7 310 27 14 3.3 1.8
17000 -25.3 -13.5 290 20 10 7.2 4.0 | -22.7 -8.9 295 23 12 6.3 3.5
16500 -24.0 -11.2 290 20 10 8.6 4.7 | -21.9 -7.4 290 22 11 6.0 3.3
16000 -22.0 -7.6 290 19 10 9.0 4.9 | -20.9 -5.6 285 21 11 7.9 4.3
15500 -20.7 -5.3 290 19 10 9.1 5.0 | -19.7 -3.5 285 21 11 8.3 4.5
15000 -19.3 -2.7 290 19 10 9.0 5.0 | -18.4 -1.1 280 21 11 8.4 4.6
14500 -18.0 -0.4 290 19 10 9.0 4.9 | -17.2 1.0 280 20 10 8.4 4.6
14000 -16.7 1.9 290 19 10 9.0 4.9 | -16.0 3.2 280 20 10 8.7 4.8
13500 -15.3 4.5 290 19 10 8.9 4.9 | -14.6 5.7 280 19 10 9.0 5.0
13000 -14.0 6.8 290 19 10 8.9 4.9 | -13.3 8.1 285 19 10 9.1 5.0
12500 -12.7 9.1 290 19 10 9.1 5.0 | -11.9 10.6 285 19 10 9.1 5.0
12000 -11.3 11.7 290 18 9 9.1 5.0 | -10.5 13.1 285 19 10 9.1 5.0
11500 -9.9 14.2 290 18 9 9.3 5.1 | -9.2 15.4 285 19 10 9.0 4.9
11000 -8.5 16.7 290 17 9 9.3 5.1 | -7.8 18.0 290 18 10 9.0 4.9
10500 -7.2 19.0 295 17 9 9.5 5.2 | -6.5 20.3 290 18 9 9.3 5.1
10250 -6.5 20.3 295 17 8 8.7 4.8 | -5.8 21.6 290 18 9 7.9 4.3
10000 -5.9 21.4 295 16 8 5.6 3.1 | -5.4 22.3 290 18 9 5.3 2.9
9750 -5.5 22.1 295 15 8 8.5 4.7 | -4.9 23.2 295 18 9 8.8 4.8
9500 -4.6 23.7 295 15 8 12.6 6.9 | -4.1 24.6 295 18 9 12.2 6.7
9250 -3.8 25.2 295 15 8 10.3 5.7 | -3.2 26.2 295 17 9 10.0 5.5
9000 -3.1 26.4 295 15 7 7.4 4.1 | -2.6 27.3 295 17 9 7.0 3.9
8750 -2.5 27.5 295 14 7 8.8 4.9 | -2.1 28.2 295 17 9 8.6 4.7
8500 -1.7 28.9 295 13 7 11.7 6.4 | -1.3 29.7 295 16 8 11.5 6.3
8250 -0.9 30.4 295 13 7 9.2 5.0 | -0.5 31.1 295 16 8 8.8 4.8
8000 -0.4 31.3 295 12 6 6.6 3.6 | 0.0 32.0 295 16 8 6.0 3.3
7750 0.2 32.4 295 11 6 9.2 5.0 | 0.6 33.1 295 15 8 9.3 5.1
7500 1.0 33.8 295 11 6 11.0 6.0 | 1.4 34.5 290 14 7 11.4 6.2
7250 1.7 35.1 290 11 6 9.1 5.0 | 2.1 35.8 290 13 7 8.4 4.6
7000 2.3 36.1 295 11 6 7.1 3.9 | 2.6 36.7 290 13 7 5.6 3.1
6750 2.9 37.2 295 11 5 11.5 6.3 | 3.1 37.6 290 13 7 11.1 6.1
6500 3.9 39.0 295 10 5 12.7 7.0 | 4.2 39.6 290 12 6 12.7 6.9
6250 4.7 40.5 295 10 5 9.6 5.3 | 4.9 40.8 290 12 6 8.5 4.7
6000 5.4 41.7 295 10 5 9.2 5.1 | 5.5 41.9 290 12 6 8.7 4.8
5750 6.2 43.2 295 9 5 12.4 6.8 | 6.2 43.2 290 11 6 10.3 5.7
5500 7.4 45.3 295 9 4 22.0 12.1 | 7.1 44.8 290 9 5 14.4 7.9
________________________________________________________________________________
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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