Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
197
UXUS97 KBOU 280017
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1817 MDT Thursday, June 27, 2024
This forecast is for Friday, June 28, 2024:
If the trigger temperature of 82.8 F/28.2 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1334 ft/min (6.8 m/s)
Maximum height of thermals.................. 17498 ft MSL (12258 ft AGL)
Forecast maximum temperature................... 91.0 F/33.2 C
Time of trigger temperature.................... 1045 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................. 12208 ft MSL (6968 ft AGL)
Thermal soaring outlook for Saturday 06/29..... 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....................... 19514 ft MSL (14274 ft AGL)
Wave soaring outlook for Saturday 06/29........ Poor
Remarks...
Sunrise/Sunset.................... 05:34:11 / 20:31:42 MDT
Total possible sunshine........... 14 hr 57 min 31 sec (897 min 31 sec)
Altitude of sun at 13:02:56 MDT... 73.44 degrees
Upper air data from numerical model forecast valid on 06/28/2024 at 0600 MDT
Freezing level.................. 15709 ft MSL (10469 ft AGL)
Convective condensation level... 15193 ft MSL (9953 ft AGL)
Lifted condensation level....... 15977 ft MSL (10737 ft AGL)
Lifted index.................... -3.9
K index......................... +28.0
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 -63.3 -81.9 250 52 27 2.6 1.5 M M M M M
45000 -57.9 -72.2 245 72 37 5.8 3.2 M M M M M
40000 -48.5 -55.3 245 83 43 7.0 3.8 M M M M M
38000 -44.3 -47.7 245 82 42 7.0 3.8 M M M M M
36000 -40.1 -40.2 245 81 42 7.1 3.9 M M M M M
34000 -36.6 -33.9 250 72 37 5.5 3.0 M M M M M
32000 -33.3 -27.9 250 63 32 5.5 3.0 M M M M M
30000 -29.7 -21.5 250 55 28 6.3 3.4 47.0 116.5 10.8 M M
29000 -27.8 -18.0 250 51 26 6.3 3.4 45.6 114.1 9.9 M M
28000 -25.5 -13.9 255 47 24 6.6 3.6 44.1 111.4 8.8 M M
27000 -23.4 -10.1 250 44 22 6.9 3.8 42.9 109.2 7.9 M M
26000 -21.4 -6.5 250 41 21 6.9 3.8 41.8 107.2 7.1 M M
25000 -19.4 -2.9 250 38 19 7.0 3.8 40.9 105.5 6.4 M M
24000 -17.3 0.9 245 35 18 6.9 3.8 39.7 103.5 5.5 M M
23000 -15.3 4.5 250 32 17 7.0 3.8 38.7 101.6 4.6 M M
22000 -13.3 8.1 250 29 15 7.1 3.9 37.8 100.0 3.8 M M
21000 -11.3 11.7 250 26 13 7.0 3.8 36.7 98.1 2.9 M M
20000 -9.3 15.3 255 22 11 7.0 3.8 35.8 96.4 2.0 M M
19500 -8.3 17.1 260 21 11 7.0 3.8 35.3 95.6 1.6 M M
19000 -7.2 19.0 260 19 10 7.1 3.9 34.9 94.8 1.3 M M
18500 -6.2 20.8 265 18 9 7.2 3.9 34.4 94.0 0.8 M M
18000 -5.1 22.8 270 16 8 7.2 3.9 34.0 93.2 0.4 M M
17500 -4.1 24.6 275 16 8 7.5 4.1 33.6 92.4 0.0 M M
17000 -3.0 26.6 280 15 8 7.5 4.1 33.2 91.7 -0.3 1091 5.5
16500 -1.9 28.6 280 15 8 7.5 4.1 32.8 91.0 -0.7 1044 5.3
16000 -0.8 30.6 285 15 8 7.5 4.1 32.4 90.3 -1.1 996 5.1
15500 0.3 32.5 290 15 8 7.8 4.3 32.1 89.7 -1.4 948 4.8
15000 1.5 34.7 290 14 7 8.5 4.6 31.8 89.2 -1.7 897 4.6
14500 2.7 36.9 290 14 7 8.5 4.6 31.6 88.9 -1.9 845 4.3
14000 4.0 39.2 290 13 7 8.2 4.5 31.4 88.4 -2.2 794 4.0
13500 5.2 41.4 290 12 6 8.2 4.5 31.1 88.0 -2.4 742 3.8
13000 6.4 43.5 290 11 6 8.7 4.8 30.9 87.6 -2.7 691 3.5
12500 8.4 47.1 290 10 5 8.7 4.8 30.7 87.2 -2.9 610 3.1
12000 9.6 49.3 290 10 5 8.6 4.7 30.5 86.9 -3.1 557 2.8
11500 10.9 51.6 290 10 5 8.8 4.8 30.3 86.5 -3.3 504 2.6
11000 12.0 53.6 295 9 5 6.8 3.7 29.9 85.9 -3.7 456 2.3
10500 13.0 55.4 295 9 5 11.2 6.2 29.5 85.0 -4.2 412 2.1
10250 14.1 57.4 300 10 5 12.4 6.8 29.8 85.7 -3.9 373 1.9
10000 14.7 58.5 300 10 5 7.6 4.2 29.7 85.5 -4.0 347 1.8
9750 15.3 59.5 300 10 5 8.8 4.8 29.6 85.4 -4.1 321 1.6
9500 15.9 60.6 300 11 5 8.8 4.8 29.6 85.2 -4.2 295 1.5
9250 16.5 61.7 300 11 6 5.3 2.9 29.4 85.4 -4.4 271 1.4
9000 16.8 62.2 295 11 6 6.4 3.5 29.0 84.2 -4.8 254 1.3
8750 17.5 63.5 295 12 6 10.2 5.6 29.0 84.1 -4.9 227 1.2
8500 18.1 64.6 295 13 7 9.3 5.1 28.9 84.1 -5.0 200 1.0
8250 18.7 65.7 295 13 7 5.7 3.1 28.8 83.9 -5.1 175 0.9
8000 19.0 66.2 295 14 7 5.4 3.0 28.4 83.1 -5.6 158 0.8
7750 19.6 67.3 295 14 7 8.8 4.8 28.3 82.9 -5.8 134 0.7
7500 20.1 68.2 295 15 8 7.6 4.2 28.1 82.7 -5.9 109 0.6
7250 20.6 69.1 295 15 8 5.4 2.9 27.9 82.2 -6.2 88 0.4
7000 21.0 69.8 290 16 8 4.2 2.3 27.5 81.5 -6.6 70 0.4
6750 21.3 70.3 290 16 8 5.2 2.8 27.1 80.8 -7.0 53 0.3
6500 21.6 70.9 285 15 8 2.7 1.5 26.7 80.1 -7.4 36 0.2
6250 21.6 70.9 280 14 7 -0.6 -0.3 26.0 78.8 -8.1 28 0.1
6000 21.6 70.9 275 12 6 -0.2 -0.1 25.3 77.5 -8.9 22 0.1
5750 21.5 70.7 270 9 5 -2.2 -1.2 24.5 76.0 -9.8 16 0.1
5500 21.1 70.0 250 6 3 -8.3 -4.5 23.4 74.0 -10.9 22 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/28/2024 at 0900 MDT | 06/28/2024 at 1200 MDT
|
CAPE... +113.3 LI... -1.2 | CAPE... +328.7 LI... -2.0
CINH... -134.4 K Index... +26.5 | CINH... -23.3 K Index... +28.4
|
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 -63.5 -82.3 245 56 29 3.1 1.7 | -63.1 -81.6 245 65 33 2.7 1.5
45000 -57.7 -71.9 250 76 39 5.7 3.1 | -58.0 -72.4 250 84 43 5.3 2.9
40000 -48.6 -55.5 245 86 44 6.3 3.4 | -49.7 -57.5 250 90 46 5.3 2.9
38000 -44.8 -48.6 250 81 42 6.3 3.4 | -46.5 -51.7 250 79 41 5.3 2.9
36000 -41.1 -42.0 250 76 39 6.3 3.5 | -43.4 -46.1 255 68 35 5.2 2.8
34000 -37.6 -35.7 255 67 35 5.7 3.1 | -39.4 -38.9 260 62 32 6.9 3.8
32000 -34.1 -29.4 255 57 29 5.8 3.2 | -35.3 -31.5 260 57 29 6.9 3.8
30000 -30.4 -22.7 260 51 26 6.4 3.5 | -30.9 -23.6 265 52 27 7.6 4.2
29000 -28.0 -18.4 260 47 24 6.5 3.6 | -28.6 -19.5 265 49 25 7.6 4.2
28000 -26.1 -15.0 260 45 23 6.9 3.8 | -25.8 -14.4 265 45 23 7.5 4.1
27000 -24.0 -11.2 260 44 22 7.3 4.0 | -23.5 -10.3 265 43 22 7.5 4.1
26000 -21.8 -7.2 260 42 22 7.3 4.0 | -21.3 -6.3 265 41 21 7.5 4.1
25000 -19.7 -3.5 260 41 21 7.4 4.1 | -19.1 -2.4 265 40 20 7.5 4.1
24000 -17.7 0.1 260 39 20 6.6 3.6 | -17.0 1.4 265 38 20 6.7 3.7
23000 -15.8 3.6 255 38 19 6.6 3.6 | -15.0 5.0 260 36 19 6.8 3.7
22000 -13.9 7.0 255 36 19 6.7 3.7 | -13.1 8.4 260 35 18 6.8 3.7
21000 -11.9 10.6 255 34 17 6.8 3.7 | -11.2 11.8 260 34 17 6.3 3.5
20000 -9.9 14.2 255 32 16 6.8 3.7 | -9.4 15.1 260 32 17 6.4 3.5
19500 -9.0 15.8 255 30 16 6.8 3.8 | -8.5 16.7 260 32 16 6.4 3.5
19000 -7.9 17.8 255 29 15 7.4 4.1 | -7.5 18.5 260 31 16 7.5 4.1
18500 -6.8 19.8 255 28 15 7.7 4.2 | -6.4 20.5 260 31 16 7.8 4.3
18000 -5.7 21.7 255 27 14 7.7 4.2 | -5.3 22.5 265 31 16 7.9 4.3
17500 -4.6 23.7 260 26 13 7.6 4.1 | -4.2 24.4 265 31 16 7.8 4.3
17000 -3.4 25.9 260 25 13 7.6 4.2 | -3.0 26.6 265 30 16 7.8 4.3
16500 -2.3 27.9 260 24 13 7.7 4.2 | -1.9 28.6 270 30 15 8.5 4.7
16000 -0.6 30.9 265 23 12 7.7 4.3 | -0.6 30.9 270 29 15 8.7 4.8
15500 0.5 32.9 265 23 12 7.6 4.2 | 0.7 33.3 270 29 15 8.7 4.8
15000 1.6 34.9 265 22 11 7.6 4.2 | 1.9 35.4 270 28 14 8.5 4.6
14500 2.7 36.9 265 21 11 7.8 4.3 | 3.7 38.7 275 26 14 8.8 4.8
14000 3.9 39.0 265 20 10 8.0 4.4 | 5.0 41.0 275 25 13 9.0 4.9
13500 5.1 41.2 265 19 10 8.2 4.5 | 6.4 43.5 275 24 12 9.0 4.9
13000 6.3 43.3 265 18 9 8.8 4.8 | 7.7 45.9 275 23 12 9.1 5.0
12500 7.6 45.7 265 18 9 8.8 4.8 | 9.0 48.2 270 22 11 9.1 5.0
12000 8.9 48.0 265 17 9 8.7 4.8 | 10.3 50.5 270 20 10 9.1 5.0
11500 10.2 50.4 265 16 8 9.0 4.9 | 11.6 52.9 270 19 10 9.2 5.1
11000 11.3 52.3 270 16 8 6.6 3.6 | 12.8 55.0 270 17 9 7.3 4.0
10500 12.3 54.1 275 15 8 9.2 5.1 | 13.9 57.0 265 15 8 11.9 6.5
10250 13.1 55.6 275 15 8 11.2 6.1 | 15.0 59.0 270 14 7 12.9 7.1
10000 13.8 56.8 275 14 7 8.1 4.4 | 15.6 60.1 270 13 7 7.6 4.2
9750 14.3 57.7 280 14 7 7.5 4.1 | 16.2 61.2 265 12 6 8.9 4.9
9500 14.9 58.8 280 14 7 8.0 4.4 | 16.9 62.4 265 11 6 8.9 4.9
9250 15.5 59.9 285 14 7 6.6 3.6 | 17.5 63.5 265 10 5 6.3 3.5
9000 15.9 60.6 290 13 7 6.9 3.8 | 17.9 64.2 260 8 4 7.4 4.1
8750 16.5 61.7 290 12 6 8.5 4.6 | 18.7 65.7 255 7 4 10.4 5.7
8500 17.1 62.8 295 12 6 8.3 4.5 | 19.4 66.9 255 6 3 10.0 5.5
8250 17.7 63.9 295 11 6 6.7 3.7 | 20.1 68.2 250 5 3 6.8 3.7
8000 18.1 64.6 305 11 6 5.7 3.1 | 20.5 68.9 240 5 2 8.1 4.4
7750 18.6 65.5 305 10 5 6.7 3.7 | 21.3 70.3 245 4 2 12.1 6.7
7500 19.0 66.2 305 9 5 6.2 3.4 | 22.2 72.0 245 4 2 10.7 5.9
7250 19.4 66.9 305 8 4 3.5 1.9 | 22.9 73.2 245 4 2 7.7 4.2
7000 19.5 67.1 315 7 4 3.0 1.6 | 23.4 74.1 235 4 2 7.8 4.3
6750 19.8 67.6 325 6 3 6.8 3.7 | 24.2 75.6 235 3 2 13.2 7.3
6500 20.4 68.7 330 5 2 7.8 4.3 | 25.2 77.4 240 3 2 12.8 7.0
6250 20.9 69.6 340 4 2 6.7 3.7 | 26.0 78.8 235 3 2 9.4 5.1
6000 21.3 70.3 355 4 2 6.5 3.6 | 26.7 80.1 230 3 1 9.1 5.0
5750 21.8 71.2 005 4 2 9.0 4.9 | 27.4 81.3 225 3 1 11.1 6.1
5500 22.7 72.9 010 3 1 16.2 8.9 | 28.5 83.3 235 3 1 21.0 11.5
06/28/2024 at 1500 MDT | 06/28/2024 at 1800 MDT
|
CAPE... +459.0 LI... -1.9 | CAPE... +470.5 LI... -2.0
CINH... -0.4 K Index... +30.4 | CINH... -43.8 K Index... +30.3
|
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 -63.6 -82.5 250 72 37 2.2 1.2 | -63.0 -81.4 260 69 36 1.4 0.8
45000 -59.0 -74.2 255 90 46 5.2 2.9 | -59.0 -74.2 255 85 44 4.9 2.7
40000 -50.6 -59.1 255 93 48 6.1 3.3 | -51.4 -60.5 255 84 43 6.4 3.5
38000 -46.9 -52.4 255 82 42 6.1 3.3 | -47.5 -53.5 260 68 35 6.4 3.5
36000 -43.3 -45.9 255 71 37 6.0 3.3 | -43.7 -46.7 265 53 27 6.4 3.5
34000 -39.2 -38.6 260 62 32 7.0 3.8 | -39.5 -39.1 265 45 23 7.0 3.8
32000 -35.0 -31.0 260 55 28 6.9 3.8 | -35.3 -31.5 265 38 20 6.9 3.8
30000 -30.7 -23.3 265 48 25 7.3 4.0 | -30.2 -22.4 265 35 18 7.8 4.3
29000 -28.5 -19.3 265 45 23 7.4 4.0 | -27.8 -18.0 265 34 18 7.8 4.3
28000 -25.8 -14.4 265 42 22 7.5 4.1 | -25.5 -13.9 265 34 17 8.0 4.4
27000 -23.5 -10.3 265 40 20 7.5 4.1 | -23.1 -9.6 265 32 17 8.0 4.4
26000 -21.3 -6.3 265 37 19 7.5 4.1 | -20.7 -5.3 260 31 16 8.1 4.4
25000 -19.1 -2.4 265 35 18 7.4 4.1 | -18.3 -0.9 260 30 15 7.9 4.4
24000 -17.1 1.2 265 33 17 6.8 3.7 | -16.2 2.8 255 29 15 7.0 3.8
23000 -15.1 4.8 260 31 16 6.9 3.8 | -14.2 6.4 255 29 15 7.0 3.9
22000 -13.1 8.4 260 29 15 7.1 3.9 | -12.1 10.2 250 29 15 7.0 3.8
21000 -11.0 12.2 260 29 15 7.4 4.1 | -10.3 13.5 250 29 15 6.4 3.5
20000 -8.9 16.0 260 28 15 7.4 4.1 | -8.5 16.7 245 28 14 6.5 3.6
19500 -7.8 18.0 260 28 15 7.4 4.1 | -7.6 18.3 245 28 14 6.5 3.6
19000 -6.7 19.9 265 28 15 7.9 4.4 | -6.6 20.1 245 27 14 7.5 4.1
18500 -5.6 21.9 265 28 14 8.0 4.4 | -5.5 22.1 245 26 13 7.6 4.2
18000 -4.4 24.1 265 28 14 8.1 4.5 | -4.5 23.9 245 25 13 7.7 4.2
17500 -3.2 26.2 265 27 14 8.5 4.7 | -3.4 25.9 245 23 12 7.7 4.2
17000 -1.9 28.6 265 26 13 8.5 4.7 | -2.2 28.0 250 22 11 7.7 4.2
16500 -0.7 30.7 265 24 13 8.6 4.7 | -1.1 30.0 250 21 11 8.6 4.7
16000 0.6 33.1 265 22 12 8.7 4.8 | 0.2 32.4 250 20 10 8.8 4.8
15500 1.8 35.2 265 21 11 9.0 4.9 | 2.2 36.0 250 18 9 9.6 5.2
15000 3.2 37.8 265 19 10 9.3 5.1 | 3.6 38.5 255 18 9 9.5 5.2
14500 4.6 40.3 265 18 9 9.3 5.1 | 5.0 41.0 255 17 9 9.3 5.1
14000 6.0 42.8 270 18 9 9.9 5.4 | 6.4 43.5 260 16 8 9.1 5.0
13500 7.5 45.5 270 18 9 9.9 5.5 | 7.7 45.9 260 16 8 9.1 5.0
13000 9.6 49.3 270 17 9 9.5 5.2 | 9.1 48.4 265 15 8 8.9 4.9
12500 11.0 51.8 270 17 9 9.5 5.2 | 10.4 50.7 270 15 8 9.0 4.9
12000 12.4 54.3 275 16 8 9.5 5.2 | 11.7 53.1 280 15 8 9.2 5.0
11500 13.8 56.8 275 15 8 9.5 5.2 | 13.0 55.4 285 15 8 9.2 5.0
11000 15.1 59.2 280 15 8 8.0 4.4 | 14.3 57.7 290 15 8 7.6 4.2
10500 16.2 61.2 280 15 8 13.5 7.4 | 15.4 59.7 295 16 8 10.8 5.9
10250 17.5 63.5 280 15 8 14.7 8.0 | 16.3 61.3 300 16 8 11.6 6.4
10000 18.2 64.8 280 15 8 8.1 4.4 | 17.0 62.6 300 17 9 8.1 4.4
9750 18.9 66.0 285 15 8 10.2 5.6 | 17.6 63.7 305 17 9 9.0 4.9
9500 19.6 67.3 285 15 8 8.5 4.6 | 18.3 64.9 305 18 9 8.8 4.8
9250 20.2 68.4 285 15 8 7.2 4.0 | 18.9 66.0 310 18 10 7.3 4.0
9000 20.8 69.4 285 15 8 9.8 5.4 | 19.4 66.9 310 19 10 8.0 4.4
8750 21.6 70.9 285 15 8 11.3 6.2 | 20.1 68.2 310 20 10 9.6 5.3
8500 22.5 72.5 285 15 8 11.0 6.0 | 20.8 69.4 310 20 10 9.3 5.1
8250 23.2 73.8 290 15 8 7.6 4.1 | 21.5 70.7 315 21 11 7.7 4.2
8000 23.7 74.7 290 15 8 8.7 4.8 | 22.0 71.6 315 21 11 7.7 4.2
7750 24.6 76.3 290 15 8 12.4 6.8 | 22.7 72.9 315 22 11 9.3 5.1
7500 25.4 77.7 290 15 8 11.0 6.0 | 23.3 73.9 315 22 11 8.8 4.8
7250 26.2 79.2 290 15 8 8.4 4.6 | 23.9 75.0 315 22 12 7.6 4.2
7000 26.7 80.1 290 15 8 8.5 4.7 | 24.5 76.1 315 22 12 7.8 4.3
6750 27.5 81.5 290 15 8 12.0 6.6 | 25.1 77.2 315 22 11 10.1 5.5
6500 28.4 83.1 295 15 8 11.6 6.4 | 25.9 78.6 315 22 11 10.4 5.7
6250 29.2 84.6 295 14 7 9.5 5.2 | 26.7 80.1 315 21 11 9.8 5.4
6000 29.9 85.8 295 14 7 9.5 5.2 | 27.4 81.3 315 20 11 9.9 5.4
5750 30.7 87.3 295 13 7 11.1 6.1 | 28.1 82.6 320 20 10 10.3 5.6
5500 31.7 89.1 295 12 6 18.6 10.2 | 29.0 84.2 320 18 9 14.0 7.7
________________________________________________________________________________
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