Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
183
UXUS97 KBOU 250027
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1821 MDT Friday, May 24, 2024
This forecast is for Saturday, May 25, 2024:
If the trigger temperature of 69.1 F/20.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 904 ft/min (4.6 m/s)
Maximum height of thermals.................. 16433 ft MSL (11108 ft AGL)
Forecast maximum temperature................... 77.0 F/25.5 C
Time of trigger temperature.................... 0945 MDT
Time of overdevelopment........................ 1200 MDT
Middle/high clouds during soaring window....... Overcast thin high
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10417 ft MSL (5093 ft AGL)
Thermal soaring outlook for Sunday 05/26....... 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....................... 39801 ft MSL (34476 ft AGL)
Wave soaring outlook for Sunday 05/26.......... Poor
Remarks...
Sunrise/Sunset.................... 05:36:30 / 20:16:32 MDT
Total possible sunshine........... 14 hr 40 min 1 sec (880 min 1 sec)
Altitude of sun at 12:56:31 MDT... 71.36 degrees
Upper air data from numerical model forecast valid on 05/25/2024 at 0600 MDT
Freezing level.................. 13145 ft MSL (7820 ft AGL)
Convective condensation level... 16442 ft MSL (11117 ft AGL)
Lifted condensation level....... 16580 ft MSL (11256 ft AGL)
Lifted index.................... -0.6
K index......................... +17.1
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 -55.5 -67.9 255 57 29 0.9 0.5 M M M M M
45000 -54.4 -65.9 255 75 39 -1.7 -0.9 M M M M M
40000 -56.8 -70.2 250 89 46 -1.6 -0.9 M M M M M
38000 -55.6 -68.1 250 85 44 3.8 2.1 M M M M M
36000 -53.3 -63.9 250 75 39 3.8 2.1 M M M M M
34000 -49.7 -57.5 245 66 34 8.1 4.5 M M M M M
32000 -44.9 -48.8 245 59 30 8.1 4.4 M M M M M
30000 -40.1 -40.2 245 53 27 7.7 4.2 35.2 95.3 7.7 M M
29000 -37.8 -36.0 240 50 26 7.7 4.2 34.3 93.7 7.1 M M
28000 -35.5 -31.9 240 48 25 7.7 4.2 33.5 92.4 6.6 M M
27000 -33.2 -27.8 240 46 24 8.7 4.7 32.9 91.2 6.2 M M
26000 -30.6 -23.1 235 45 23 8.6 4.7 32.4 90.3 5.8 M M
25000 -28.0 -18.4 235 44 23 8.6 4.7 31.9 89.5 5.6 M M
24000 -25.4 -13.7 235 43 22 8.0 4.4 31.6 88.9 5.4 M M
23000 -23.1 -9.6 235 43 22 7.7 4.2 30.7 87.3 4.7 M M
22000 -20.8 -5.4 240 43 22 7.7 4.2 30.0 86.0 4.1 M M
21000 -18.5 -1.3 240 42 22 7.6 4.2 29.3 84.8 3.6 M M
20000 -16.3 2.7 240 40 20 7.6 4.2 28.5 83.3 2.9 M M
19500 -15.1 4.8 240 39 20 7.6 4.2 28.1 82.6 2.6 M M
19000 -14.0 6.8 240 37 19 7.6 4.2 27.8 82.0 2.3 M M
18500 -12.9 8.8 235 36 19 6.6 3.6 27.4 81.3 2.0 M M
18000 -11.6 11.1 230 33 17 6.1 3.4 26.4 79.6 1.1 M M
17500 -10.7 12.7 230 31 16 7.4 4.1 25.9 78.6 0.6 M M
17000 -9.5 14.9 225 29 15 8.1 4.4 25.6 78.0 0.3 M M
16500 -8.4 16.9 220 26 13 8.1 4.5 25.3 77.6 -0.0 1001 5.1
16000 -7.2 19.0 220 25 13 8.0 4.4 25.0 77.0 -0.3 951 4.8
15500 -6.0 21.2 225 25 13 8.0 4.4 24.7 76.5 -0.6 902 4.6
15000 -4.8 23.4 230 25 13 8.5 4.7 24.5 76.1 -0.9 851 4.3
14500 -3.6 25.5 235 24 12 8.5 4.7 24.3 75.7 -1.1 799 4.1
14000 -2.3 27.9 240 24 12 9.3 5.1 24.1 75.4 -1.3 746 3.8
13500 -0.9 30.4 245 23 12 9.5 5.2 24.1 75.3 -1.4 689 3.5
13000 0.5 32.9 250 23 12 8.8 4.8 24.1 75.3 -1.4 631 3.2
12500 1.7 35.1 250 22 11 8.1 4.4 23.8 74.8 -1.7 581 2.9
12000 2.9 37.2 250 20 10 8.1 4.5 23.5 74.3 -2.0 530 2.7
11500 4.2 39.6 255 20 10 8.2 4.5 23.3 73.9 -2.2 478 2.4
11000 5.4 41.7 255 19 10 7.6 4.2 23.0 73.5 -2.4 425 2.2
10500 6.4 43.5 255 17 9 5.8 3.2 22.5 72.5 -2.9 382 1.9
10250 6.8 44.2 255 15 8 7.3 4.0 22.2 72.0 -3.2 361 1.8
10000 7.5 45.5 255 15 8 7.6 4.2 22.1 71.8 -3.3 335 1.7
9750 7.9 46.2 255 13 7 5.6 3.1 21.8 71.3 -3.6 313 1.6
9500 8.3 46.9 260 12 6 5.4 2.9 21.5 70.7 -3.9 294 1.5
9250 8.7 47.7 260 11 5 5.6 3.1 21.1 70.1 -4.3 275 1.4
9000 9.1 48.4 265 9 5 4.5 2.5 20.8 69.5 -4.6 256 1.3
8750 9.4 48.9 270 9 5 3.7 2.1 20.3 68.6 -5.1 240 1.2
8500 9.7 49.5 275 8 4 4.1 2.3 19.9 67.8 -5.5 224 1.1
8250 10.0 50.0 280 8 4 4.2 2.3 19.5 67.0 -6.0 208 1.1
8000 10.3 50.5 295 7 4 5.6 3.1 19.1 66.3 -6.4 190 1.0
7750 10.7 51.3 305 7 4 4.2 2.3 18.7 65.7 -6.8 171 0.9
7500 10.9 51.6 315 8 4 2.3 1.3 18.2 64.8 -7.3 158 0.8
7250 11.1 52.0 320 8 4 2.8 1.5 17.7 63.8 -7.9 145 0.7
7000 11.3 52.3 325 8 4 2.8 1.5 17.1 62.8 -8.4 132 0.7
6750 11.5 52.7 330 9 4 2.4 1.3 16.6 61.9 -9.0 118 0.6
6500 11.6 52.9 335 9 4 2.9 1.6 16.0 60.9 -9.6 106 0.5
6250 11.8 53.2 335 8 4 0.4 0.2 15.5 59.9 -10.1 93 0.5
6000 11.7 53.1 335 7 4 -2.0 -1.1 14.6 58.3 -11.0 90 0.5
5750 11.5 52.7 330 5 3 -2.4 -1.3 13.8 56.8 -12.0 87 0.4
5500 11.1 52.0 310 3 2 -9.2 -5.0 12.6 54.7 -13.2 93 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/25/2024 at 0900 MDT | 05/25/2024 at 1200 MDT
|
CAPE... +22.4 LI... +2.3 | CAPE... +60.3 LI... +0.6
CINH... -40.2 K Index... +2.0 | CINH... -44.1 K Index... +16.3
|
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 -55.3 -67.5 255 62 32 1.0 0.6 | -53.9 -65.0 250 64 33 0.6 0.4
45000 -53.9 -65.0 250 74 38 -0.9 -0.5 | -53.0 -63.4 250 73 38 -0.1 -0.0
40000 -55.2 -67.4 240 86 44 -0.9 -0.5 | -53.1 -63.6 240 78 40 -0.0 -0.0
38000 -54.4 -65.9 240 86 44 2.7 1.5 | -52.3 -62.1 240 77 39 2.2 1.2
36000 -52.8 -63.0 240 83 43 2.7 1.5 | -50.9 -59.6 235 74 38 2.2 1.2
34000 -50.0 -58.0 240 77 40 7.3 4.0 | -49.0 -56.2 230 70 36 4.8 2.6
32000 -45.6 -50.1 235 69 35 7.3 4.0 | -46.1 -51.0 230 64 33 4.8 2.7
30000 -40.9 -41.6 235 62 32 8.6 4.7 | -42.4 -44.3 225 58 30 8.8 4.8
29000 -38.4 -37.1 235 61 31 8.6 4.7 | -39.8 -39.6 220 55 28 8.8 4.9
28000 -35.8 -32.4 235 59 31 8.6 4.7 | -37.1 -34.8 220 53 27 8.9 4.9
27000 -33.3 -27.9 230 58 30 8.2 4.5 | -34.5 -30.1 220 50 26 8.2 4.5
26000 -30.8 -23.4 230 56 29 8.2 4.5 | -32.1 -25.8 220 50 26 8.0 4.4
25000 -28.3 -18.9 230 55 28 8.2 4.5 | -29.7 -21.5 220 49 25 8.0 4.4
24000 -25.9 -14.6 230 53 27 8.0 4.4 | -27.4 -17.3 225 49 25 8.0 4.4
23000 -23.5 -10.3 235 51 26 7.8 4.3 | -24.9 -12.8 225 47 24 8.1 4.5
22000 -21.2 -6.2 235 50 26 7.8 4.3 | -22.5 -8.5 230 45 23 8.1 4.5
21000 -18.8 -1.8 235 48 25 7.9 4.4 | -20.0 -4.0 235 44 23 7.9 4.3
20000 -16.4 2.5 235 46 24 7.9 4.4 | -17.7 0.1 235 42 22 7.7 4.2
19500 -15.2 4.6 235 45 23 7.9 4.4 | -16.5 2.3 235 41 21 7.7 4.2
19000 -14.0 6.8 235 45 23 7.9 4.4 | -14.8 5.4 235 39 20 7.8 4.3
18500 -12.2 10.0 240 43 22 7.9 4.3 | -13.7 7.3 240 38 20 7.6 4.2
18000 -11.1 12.0 240 43 22 7.9 4.3 | -12.5 9.5 240 37 19 7.6 4.2
17500 -9.9 14.2 240 42 22 7.7 4.2 | -11.4 11.5 240 37 19 7.7 4.2
17000 -8.8 16.2 240 41 21 7.5 4.1 | -10.3 13.5 245 35 18 7.7 4.2
16500 -7.6 18.3 240 40 21 7.5 4.1 | -9.2 15.4 245 33 17 7.7 4.2
16000 -6.5 20.3 240 39 20 7.2 4.0 | -8.0 17.6 245 32 16 8.4 4.6
15500 -5.5 22.1 240 38 19 7.3 4.0 | -6.8 19.8 245 30 15 8.4 4.6
15000 -4.4 24.1 240 36 19 7.1 3.9 | -5.6 21.9 245 28 15 8.4 4.6
14500 -3.4 25.9 240 35 18 7.1 3.9 | -4.3 24.3 245 27 14 8.5 4.6
14000 -2.4 27.7 240 33 17 7.4 4.1 | -3.1 26.4 245 26 13 8.8 4.8
13500 -1.3 29.7 240 31 16 7.7 4.2 | -1.7 28.9 245 25 13 9.1 5.0
13000 -0.2 31.6 240 29 15 8.0 4.4 | -0.4 31.3 245 24 12 9.0 5.0
12500 1.1 34.0 240 28 14 8.4 4.6 | 0.9 33.6 245 24 12 8.8 4.8
12000 2.3 36.1 245 26 14 8.4 4.6 | 2.2 36.0 245 23 12 8.8 4.8
11500 3.5 38.3 245 25 13 8.2 4.5 | 3.5 38.3 240 22 12 8.9 4.9
11000 4.7 40.5 245 24 12 8.0 4.4 | 4.9 40.8 240 22 11 8.8 4.8
10500 5.8 42.4 250 22 12 6.7 3.7 | 6.2 43.2 235 22 11 8.2 4.5
10250 6.3 43.3 250 22 11 8.4 4.6 | 6.8 44.2 235 21 11 9.7 5.3
10000 7.0 44.6 250 21 11 9.3 5.1 | 7.6 45.7 235 21 11 10.8 5.9
9750 7.6 45.7 255 20 10 7.5 4.1 | 8.3 46.9 235 20 11 9.4 5.1
9500 8.1 46.6 255 19 10 6.9 3.8 | 9.0 48.2 235 20 10 9.1 5.0
9250 8.6 47.5 255 18 9 7.3 4.0 | 9.7 49.5 235 20 10 9.0 4.9
9000 9.2 48.6 255 17 9 7.0 3.9 | 10.3 50.5 235 19 10 8.1 4.5
8750 9.7 49.5 255 16 8 6.3 3.5 | 10.9 51.6 235 18 9 8.0 4.4
8500 10.1 50.2 255 15 8 6.0 3.3 | 11.5 52.7 235 17 9 8.5 4.6
8250 10.6 51.1 250 14 7 6.3 3.5 | 12.1 53.8 235 15 8 8.0 4.4
8000 11.0 51.8 250 12 6 5.4 2.9 | 12.7 54.9 235 14 7 9.6 5.3
7750 11.4 52.5 250 11 5 4.9 2.7 | 13.5 56.3 235 14 7 10.1 5.5
7500 11.7 53.1 250 10 5 5.5 3.0 | 14.2 57.6 235 13 7 8.8 4.8
7250 12.1 53.8 245 9 5 5.0 2.8 | 14.8 58.6 240 13 6 9.1 5.0
7000 12.4 54.3 245 8 4 3.1 1.7 | 15.5 59.9 240 12 6 8.3 4.5
6750 12.7 54.9 250 6 3 4.6 2.5 | 16.1 61.0 240 12 6 10.0 5.5
6500 13.1 55.6 250 5 3 6.5 3.6 | 17.0 62.6 240 12 6 11.7 6.4
6250 13.5 56.3 250 5 2 6.9 3.8 | 17.8 64.0 240 11 6 11.1 6.1
6000 14.1 57.4 240 4 2 8.8 4.8 | 18.7 65.7 240 11 5 11.6 6.4
5750 14.7 58.5 225 3 2 8.2 4.5 | 19.5 67.1 240 11 6 8.6 4.7
5500 15.4 59.7 240 3 2 11.4 6.3 | 20.1 68.2 240 9 5 13.2 7.2
05/25/2024 at 1500 MDT | 05/25/2024 at 1800 MDT
|
CAPE... +388.6 LI... -1.6 | CAPE... +142.3 LI... -0.8
CINH... -32.0 K Index... +24.2 | CINH... -37.0 K Index... +24.3
|
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 -52.7 -62.9 255 61 31 0.9 0.5 | -52.5 -62.5 255 50 26 0.6 0.3
45000 -51.4 -60.5 250 68 35 0.0 0.0 | -51.5 -60.7 255 61 31 0.9 0.5
40000 -51.2 -60.2 245 71 36 0.1 0.1 | -50.0 -58.0 255 61 31 1.0 0.5
38000 -50.6 -59.1 245 68 35 1.5 0.8 | -49.8 -57.6 255 57 29 0.0 0.0
36000 -49.7 -57.5 240 64 33 1.5 0.8 | -49.8 -57.6 255 50 26 0.0 0.0
34000 -48.3 -54.9 240 60 31 5.7 3.1 | -49.3 -56.7 260 43 22 4.8 2.6
32000 -44.9 -48.8 240 57 29 5.6 3.1 | -46.6 -51.9 265 34 18 4.5 2.5
30000 -41.6 -42.9 240 53 27 4.9 2.7 | -42.8 -45.0 270 27 14 8.5 4.7
29000 -39.7 -39.5 245 46 24 5.0 2.7 | -40.2 -40.4 270 25 13 8.6 4.7
28000 -38.3 -36.9 245 41 21 5.0 2.7 | -37.6 -35.7 270 23 12 8.6 4.7
27000 -36.7 -34.1 245 36 18 7.8 4.3 | -35.1 -31.2 265 21 11 8.5 4.7
26000 -34.1 -29.4 245 34 18 8.6 4.7 | -32.5 -26.5 260 21 11 8.5 4.7
25000 -31.5 -24.7 245 32 17 8.7 4.7 | -30.0 -22.0 255 22 11 8.5 4.7
24000 -29.0 -20.2 245 30 16 8.8 4.8 | -27.5 -17.5 255 23 12 8.2 4.5
23000 -26.3 -15.3 245 29 15 9.0 4.9 | -25.2 -13.4 255 23 12 7.6 4.2
22000 -23.7 -10.7 245 27 14 9.0 4.9 | -23.0 -9.4 255 23 12 7.7 4.2
21000 -21.0 -5.8 245 25 13 8.2 4.5 | -20.7 -5.3 255 24 12 7.8 4.3
20000 -18.7 -1.7 245 24 13 8.1 4.4 | -18.4 -1.1 255 25 13 7.8 4.3
19500 -17.5 0.5 245 24 12 8.1 4.4 | -17.3 0.9 260 25 13 7.8 4.3
19000 -16.3 2.7 240 23 12 8.1 4.4 | -16.1 3.0 260 26 13 7.8 4.3
18500 -15.1 4.8 240 23 12 7.9 4.3 | -15.0 5.0 260 26 13 7.8 4.3
18000 -14.0 6.8 240 22 12 7.7 4.2 | -13.9 7.0 260 26 13 7.7 4.2
17500 -12.8 9.0 240 22 11 7.6 4.2 | -12.7 9.1 265 26 13 7.7 4.2
17000 -11.6 11.1 240 21 11 9.7 5.3 | -11.6 11.1 265 26 13 7.5 4.1
16500 -10.2 13.6 240 21 11 9.5 5.2 | -10.0 14.0 265 25 13 7.5 4.1
16000 -8.8 16.2 240 21 11 9.3 5.1 | -8.8 16.2 270 25 13 7.8 4.3
15500 -7.4 18.7 235 20 10 9.2 5.0 | -7.7 18.1 270 25 13 7.7 4.2
15000 -6.0 21.2 235 19 10 9.2 5.0 | -6.5 20.3 270 24 12 8.9 4.9
14500 -4.0 24.8 235 18 9 9.3 5.1 | -5.1 22.8 270 24 12 9.1 5.0
14000 -2.6 27.3 235 17 9 9.1 5.0 | -3.8 25.2 275 24 12 9.2 5.0
13500 -1.2 29.8 235 16 8 8.9 4.9 | -2.4 27.7 275 23 12 9.2 5.1
13000 0.1 32.2 235 15 8 9.0 4.9 | -1.0 30.2 275 22 11 9.3 5.1
12500 1.4 34.5 235 14 7 9.0 4.9 | 0.4 32.7 280 21 11 9.6 5.3
12000 2.8 37.0 230 12 6 9.0 4.9 | 1.8 35.2 280 20 10 9.6 5.2
11500 4.1 39.4 235 11 6 8.9 4.9 | 3.3 37.9 280 19 10 9.5 5.2
11000 5.4 41.7 235 9 5 9.0 4.9 | 4.7 40.5 280 18 9 9.5 5.2
10500 6.8 44.2 240 7 4 9.1 5.0 | 6.1 43.0 280 17 9 9.5 5.2
10250 7.4 45.3 240 7 3 9.6 5.3 | 6.8 44.2 280 17 9 9.0 4.9
10000 8.2 46.8 245 6 3 10.0 5.5 | 7.4 45.3 280 16 8 9.0 5.0
9750 8.9 48.0 250 6 3 9.6 5.3 | 8.1 46.6 280 15 8 10.1 5.5
9500 9.6 49.3 260 5 3 9.8 5.4 | 8.9 48.0 280 15 8 10.8 5.9
9250 10.3 50.5 270 5 3 8.9 4.9 | 9.7 49.5 280 14 7 9.6 5.2
9000 10.9 51.6 275 5 2 7.9 4.3 | 10.3 50.5 275 13 7 7.0 3.8
8750 11.5 52.7 285 5 2 9.3 5.1 | 10.8 51.4 275 13 7 7.7 4.2
8500 12.3 54.1 290 5 3 10.0 5.5 | 11.4 52.5 275 12 6 9.3 5.1
8250 13.0 55.4 300 5 3 10.4 5.7 | 12.1 53.8 275 12 6 8.3 4.5
8000 13.7 56.7 305 5 3 8.2 4.5 | 12.7 54.9 270 12 6 10.9 6.0
7750 14.2 57.6 310 6 3 8.0 4.4 | 13.6 56.5 270 11 6 10.0 5.5
7500 14.9 58.8 310 6 3 10.1 5.5 | 14.2 57.6 265 11 6 6.8 3.7
7250 15.7 60.3 315 7 3 9.5 5.2 | 14.7 58.5 265 11 5 7.5 4.1
7000 16.4 61.5 315 7 4 9.3 5.1 | 15.3 59.5 260 10 5 9.1 5.0
6750 17.1 62.8 315 7 4 9.5 5.2 | 16.0 60.8 260 10 5 9.5 5.2
6500 17.8 64.0 320 8 4 10.0 5.5 | 16.7 62.1 260 10 5 8.1 4.4
6250 18.5 65.3 320 8 4 9.8 5.4 | 17.3 63.1 255 10 5 9.0 4.9
6000 19.2 66.6 320 8 4 9.3 5.1 | 18.0 64.4 255 10 5 10.8 5.9
5750 20.0 68.0 320 8 4 10.9 6.0 | 18.8 65.8 255 9 5 9.7 5.3
5500 20.9 69.6 315 8 4 14.4 7.9 | 19.4 66.9 250 8 4 9.1 5.0
________________________________________________________________________________
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