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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 120010
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1810 MDT Saturday, May 11, 2013
This forecast is for Sunday, May 12, 2013:
If the trigger temperature of 65.2 F/18.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1344 ft/min (6.8 m/s)
Maximum height of thermals.................. 19966 ft MSL (14679 ft AGL)
Forecast maximum temperature................... 79.0 F/26.6 C
Time of trigger temperature.................... 0930 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................. 17165 ft MSL (11878 ft AGL)
Thermal soaring outlook for Monday 05/13....... Excellent
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....................... 39506 ft MSL (34219 ft AGL)
Wave soaring outlook for Monday 05/13.......... Poor
Remarks... None
Sunrise/Sunset.................... 05:47:34 / 20:03:55 MDT
Total possible sunshine........... 14 hr 16 min 21 sec (856 min 21 sec)
Altitude of sun at 12:55:55 MDT... 68.54 degrees
Upper air data from numerical model forecast valid on 05/12/2013 at 0600 MDT
Freezing level.................. 11783 ft MSL (6496 ft AGL)
Convective condensation level... 13769 ft MSL (8482 ft AGL)
Lifted condensation level....... 16357 ft MSL (11069 ft AGL)
Lifted index.................... -2.4
K index......................... +21.0
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 -61.8 -79.2 340 21 11 0.9 0.5 M M M M M
45000 -60.6 -77.1 355 36 19 -0.5 -0.3 M M M M M
40000 -61.3 -78.3 015 62 32 -0.3 -0.2 M M M M M
38000 -59.1 -74.4 015 62 32 5.3 2.9 M M M M M
36000 -55.9 -68.6 020 59 31 5.3 2.9 M M M M M
34000 -51.8 -61.2 015 56 29 8.8 4.8 M M M M M
32000 -46.6 -51.9 015 53 27 8.8 4.8 M M M M M
30000 -40.6 -41.1 010 49 25 8.7 4.8 34.8 94.6 6.5 M M
29000 -38.0 -36.4 010 46 24 8.8 4.8 34.4 93.8 6.3 M M
28000 -35.4 -31.7 010 44 23 8.7 4.8 34.1 93.3 6.1 M M
27000 -32.9 -27.2 010 42 21 8.3 4.5 33.6 92.4 5.8 M M
26000 -30.4 -22.7 005 39 20 8.2 4.5 32.9 91.3 5.4 M M
25000 -27.9 -18.2 360 36 18 8.2 4.5 32.4 90.4 5.0 M M
24000 -25.7 -14.3 360 33 17 5.8 3.2 31.6 88.9 4.4 M M
23000 -23.9 -11.0 355 31 16 6.0 3.3 30.1 86.2 3.2 M M
22000 -22.2 -8.0 350 29 15 6.0 3.3 28.8 83.9 2.2 M M
21000 -20.3 -4.5 350 28 14 6.5 3.6 27.6 81.6 1.1 M M
20000 -18.4 -1.1 350 27 14 6.5 3.6 26.4 79.5 0.1 M M
19500 -17.4 0.7 350 27 14 6.5 3.6 25.9 78.5 -0.4 1308 6.6
19000 -16.5 2.3 350 26 13 6.5 3.5 25.3 77.6 -0.8 1264 6.4
18500 -15.5 4.1 350 26 13 6.1 3.4 24.7 76.5 -1.4 1222 6.2
18000 -14.6 5.7 350 25 13 6.1 3.4 24.1 75.4 -2.0 1180 6.0
17500 -13.7 7.3 350 24 13 6.5 3.6 23.5 74.3 -2.5 1138 5.8
17000 -12.8 9.0 350 23 12 6.5 3.6 22.9 73.3 -3.1 1095 5.6
16500 -11.8 10.8 350 21 11 6.5 3.6 22.4 72.4 -3.6 1052 5.3
16000 -10.9 12.4 350 19 10 6.6 3.6 21.9 71.3 -4.1 1008 5.1
15500 -9.4 15.1 350 16 8 7.3 4.0 21.1 70.0 -4.9 942 4.8
15000 -8.3 17.1 350 15 7 7.6 4.2 20.7 69.3 -5.3 895 4.5
14500 -7.2 19.0 350 13 7 8.2 4.5 20.4 68.7 -5.7 847 4.3
14000 -5.9 21.4 355 13 7 8.8 4.8 20.2 68.4 -5.9 793 4.0
13500 -4.6 23.7 355 13 7 9.0 4.9 20.1 68.1 -6.1 739 3.8
13000 -3.2 26.2 355 13 7 9.5 5.2 20.0 68.0 -6.2 683 3.5
12500 -1.8 28.8 355 14 7 9.5 5.2 20.0 67.9 -6.3 626 3.2
12000 -0.4 31.3 355 14 7 9.4 5.1 19.9 67.8 -6.4 569 2.9
11500 1.0 33.8 355 15 8 9.3 5.1 19.8 67.7 -6.5 513 2.6
11000 2.3 36.1 350 16 8 8.9 4.9 19.7 67.5 -6.6 457 2.3
10500 3.7 38.7 350 17 9 6.8 3.7 19.6 67.3 -6.8 402 2.0
10250 4.0 39.2 350 18 9 4.1 2.2 19.2 66.6 -7.2 385 2.0
10000 4.5 40.1 350 18 9 9.1 5.0 18.9 66.1 -7.4 363 1.8
9750 5.3 41.5 350 19 10 12.7 7.0 19.1 66.4 -7.3 330 1.7
9500 6.2 43.2 345 20 10 9.7 5.3 19.2 66.6 -7.2 297 1.5
9250 6.8 44.2 345 20 11 6.1 3.4 19.1 66.3 -7.4 273 1.4
9000 7.3 45.1 345 21 11 8.5 4.7 18.8 65.9 -7.6 250 1.3
8750 8.0 46.4 345 21 11 11.6 6.4 18.9 66.0 -7.6 219 1.1
8500 8.8 47.8 345 22 11 9.3 5.1 19.0 66.2 -7.6 188 1.0
8250 9.4 48.9 345 21 11 7.7 4.2 18.9 65.9 -7.7 162 0.8
8000 10.0 50.0 340 21 11 8.4 4.6 18.7 65.7 -7.9 137 0.7
7750 10.7 51.3 340 21 11 8.3 4.5 18.6 65.5 -8.0 111 0.6
7500 11.2 52.2 335 20 10 7.5 4.1 18.5 65.3 -8.2 86 0.4
7250 11.7 53.1 330 19 10 6.5 3.5 18.3 64.9 -8.4 64 0.3
7000 12.3 54.1 325 18 9 8.4 4.6 18.1 64.5 -8.7 41 0.2
6750 12.9 55.2 320 18 9 5.8 3.2 18.0 64.3 -8.8 16 0.1
6500 13.0 55.4 310 18 9 0.9 0.5 17.4 63.3 -9.4 4 0.0
6250 13.1 55.6 300 18 9 2.8 1.6 16.8 62.2 -10.1 M M
6000 13.2 55.8 290 19 10 -2.9 -1.6 16.2 61.1 -10.7 M M
5750 12.3 54.1 285 17 9 -17.8 -9.8 14.7 58.4 -12.3 2 0.0
5500 10.5 50.9 275 12 6 -25.7 -14.1 12.2 54.0 -14.9 49 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/12/2013 at 0900 MDT | 05/12/2013 at 1200 MDT
|
K index... +13.7 LI... +0.9 | K index... +15.5 LI... -0.1
CAPE... 0.0 CIN... -2.0 | CAPE... +4.8 CIN... -21.2
|
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 -62.9 -81.2 345 28 14 0.0 0.0 | -63.1 -81.6 350 26 13 -0.5 -0.3
45000 -62.9 -81.2 355 40 21 -0.4 -0.2 | -63.8 -82.8 005 37 19 -0.7 -0.4
40000 -63.5 -82.3 015 68 35 -0.4 -0.2 | -64.8 -84.6 020 69 36 -1.1 -0.6
38000 -60.3 -76.5 020 69 36 7.1 3.9 | -60.7 -77.3 025 70 36 8.6 4.7
36000 -56.0 -68.8 020 67 35 7.1 3.9 | -55.5 -67.9 025 67 34 8.6 4.7
34000 -51.2 -60.2 020 66 34 9.4 5.2 | -49.4 -56.9 020 64 33 9.3 5.1
32000 -45.5 -49.9 020 65 33 9.4 5.1 | -43.8 -46.8 020 63 32 9.3 5.1
30000 -39.5 -39.1 015 62 32 8.4 4.6 | -38.5 -37.3 020 59 30 8.5 4.7
29000 -37.0 -34.6 015 60 31 8.4 4.6 | -35.9 -32.6 020 56 29 8.5 4.7
28000 -34.5 -30.1 015 58 30 8.4 4.6 | -33.4 -28.1 020 54 28 8.6 4.7
27000 -31.9 -25.4 015 56 29 8.5 4.6 | -30.9 -23.6 020 51 26 7.9 4.3
26000 -29.4 -20.9 015 55 28 8.5 4.6 | -28.6 -19.5 020 47 24 7.9 4.3
25000 -26.9 -16.4 015 53 27 8.4 4.6 | -26.2 -15.2 020 43 22 7.9 4.3
24000 -24.5 -12.1 015 50 26 7.1 3.9 | -23.8 -10.8 020 41 21 8.1 4.4
23000 -22.4 -8.3 010 44 23 7.1 3.9 | -21.4 -6.5 020 40 20 8.1 4.4
22000 -20.3 -4.5 005 39 20 7.1 3.9 | -19.0 -2.2 015 38 20 8.2 4.5
21000 -18.4 -1.1 360 35 18 5.6 3.0 | -17.4 0.7 010 36 18 3.5 1.9
20000 -16.8 1.8 355 32 17 5.6 3.0 | -16.4 2.5 005 33 17 3.5 1.9
19500 -16.0 3.2 355 31 16 5.6 3.1 | -15.9 3.4 005 31 16 3.6 2.0
19000 -15.2 4.6 350 29 15 5.8 3.2 | -15.4 4.3 360 30 15 4.6 2.5
18500 -14.3 6.3 350 29 15 6.1 3.4 | -14.5 5.9 360 29 15 6.1 3.4
18000 -13.4 7.9 350 28 14 6.2 3.4 | -13.6 7.5 355 28 14 6.0 3.3
17500 -12.5 9.5 350 27 14 6.1 3.3 | -12.6 9.3 355 27 14 7.7 4.2
17000 -11.6 11.1 350 27 14 6.1 3.4 | -11.5 11.3 350 26 14 7.6 4.2
16500 -10.7 12.7 350 26 14 6.5 3.6 | -9.8 14.4 350 26 13 7.6 4.1
16000 -9.7 14.5 350 26 13 6.8 3.7 | -8.7 16.3 345 26 13 7.6 4.2
15500 -8.2 17.2 345 25 13 7.1 3.9 | -7.6 18.3 345 26 13 7.6 4.1
15000 -7.1 19.2 345 23 12 7.2 4.0 | -6.4 20.5 345 25 13 7.6 4.1
14500 -6.0 21.2 345 22 11 7.2 4.0 | -5.3 22.5 345 25 13 7.7 4.2
14000 -5.3 22.5 345 19 10 7.3 4.0 | -4.2 24.4 345 25 13 7.8 4.3
13500 -3.9 25.0 340 17 9 7.4 4.1 | -3.0 26.6 340 25 13 7.8 4.3
13000 -2.7 27.1 340 15 8 7.8 4.3 | -1.9 28.6 345 24 12 7.9 4.3
12500 -1.6 29.1 335 13 7 7.9 4.3 | -0.7 30.7 345 23 12 8.0 4.4
12000 -0.4 31.3 335 12 6 8.3 4.6 | 0.5 32.9 345 22 11 8.3 4.6
11500 0.8 33.4 335 11 6 8.5 4.6 | 1.8 35.2 345 20 10 8.2 4.5
11000 2.1 35.8 340 12 6 8.8 4.8 | 2.9 37.2 345 18 9 7.7 4.2
10500 3.4 38.1 345 13 7 6.8 3.7 | 4.0 39.2 345 15 8 5.5 3.0
10250 3.8 38.8 345 13 7 5.1 2.8 | 4.3 39.7 345 15 8 4.6 2.5
10000 4.3 39.7 345 14 7 10.2 5.6 | 4.8 40.6 345 14 7 10.3 5.7
9750 5.2 41.4 345 15 8 13.3 7.3 | 5.7 42.3 345 13 7 12.9 7.1
9500 6.1 43.0 350 16 8 10.1 5.5 | 6.5 43.7 340 12 6 10.2 5.6
9250 6.7 44.1 350 16 8 6.4 3.5 | 7.2 45.0 340 12 6 7.2 3.9
9000 7.2 45.0 345 16 8 9.2 5.0 | 7.8 46.0 340 12 6 10.5 5.8
8750 8.0 46.4 345 16 8 11.8 6.5 | 8.7 47.7 340 11 6 12.9 7.1
8500 8.8 47.8 345 16 8 9.3 5.1 | 9.6 49.3 340 11 6 10.0 5.5
8250 9.4 48.9 345 16 8 7.6 4.2 | 10.2 50.4 340 11 6 8.2 4.5
8000 10.0 50.0 345 16 8 9.0 5.0 | 10.9 51.6 340 11 6 9.9 5.4
7750 10.8 51.4 340 16 8 10.2 5.6 | 11.7 53.1 340 11 5 11.3 6.2
7500 11.5 52.7 340 16 8 9.0 5.0 | 12.5 54.5 340 10 5 10.3 5.7
7250 12.1 53.8 340 15 8 8.2 4.5 | 13.2 55.8 340 10 5 9.9 5.5
7000 12.7 54.9 335 15 8 8.8 4.8 | 14.0 57.2 340 10 5 9.8 5.4
6750 13.3 55.9 335 14 7 7.0 3.8 | 14.7 58.5 340 10 5 9.9 5.4
6500 13.7 56.7 325 12 6 5.6 3.1 | 15.5 59.9 340 10 5 10.5 5.7
6250 14.1 57.4 315 11 6 5.2 2.9 | 16.3 61.3 340 10 5 9.8 5.4
6000 14.5 58.1 305 10 5 8.4 4.6 | 17.0 62.6 335 10 5 11.8 6.5
5750 15.3 59.5 295 9 5 13.9 7.6 | 18.1 64.6 335 9 5 17.9 9.8
5500 16.3 61.3 290 8 4 13.2 7.3 | 19.6 67.3 340 8 4 22.4 12.3
05/12/2013 at 1500 MDT | 05/12/2013 at 1800 MDT
|
K index... +17.3 LI... +0.2 | K index... +21.4 LI... -0.7
CAPE... +20.2 CIN... -38.4 | CAPE... +20.0 CIN... -64.3
|
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 -63.7 -82.7 360 23 12 -0.5 -0.3 | -65.5 -85.9 360 24 12 -0.7 -0.4
45000 -64.4 -83.9 020 36 19 0.4 0.2 | -66.1 -87.0 015 40 21 1.9 1.0
40000 -63.8 -82.8 020 66 34 1.8 1.0 | -63.2 -81.8 025 60 31 1.1 0.6
38000 -59.0 -74.2 025 62 32 8.6 4.7 | -58.6 -73.5 020 56 29 8.4 4.6
36000 -53.8 -64.8 025 57 30 8.6 4.7 | -52.9 -63.2 020 49 25 8.4 4.6
34000 -48.7 -55.7 020 55 28 8.7 4.8 | -47.7 -53.9 015 45 23 8.5 4.7
32000 -43.4 -46.1 015 54 28 8.7 4.8 | -42.6 -44.7 010 43 22 8.5 4.7
30000 -38.3 -36.9 010 51 26 8.4 4.6 | -37.7 -35.9 005 41 21 8.1 4.4
29000 -35.8 -32.4 010 48 25 8.4 4.6 | -35.2 -31.4 005 39 20 8.1 4.5
28000 -33.3 -27.9 010 45 23 8.4 4.6 | -32.8 -27.0 005 38 20 8.1 4.5
27000 -30.4 -22.7 010 41 21 7.7 4.2 | -30.4 -22.7 005 37 19 8.1 4.4
26000 -28.1 -18.6 010 38 20 7.7 4.2 | -28.0 -18.4 005 36 19 8.1 4.5
25000 -25.8 -14.4 010 35 18 7.7 4.2 | -25.6 -14.1 010 35 18 8.1 4.5
24000 -23.5 -10.3 010 34 17 7.8 4.3 | -23.3 -9.9 010 34 18 7.3 4.0
23000 -21.1 -6.0 010 33 17 7.8 4.3 | -21.1 -6.0 005 34 17 7.3 4.0
22000 -18.8 -1.8 005 33 17 8.1 4.4 | -18.9 -2.0 005 33 17 7.4 4.1
21000 -16.9 1.6 005 32 16 5.8 3.2 | -17.0 1.4 360 32 17 5.9 3.3
20000 -15.2 4.6 005 30 16 5.8 3.2 | -15.2 4.6 360 32 16 6.0 3.3
19500 -14.4 6.1 005 30 15 5.8 3.2 | -14.3 6.3 360 32 16 6.0 3.3
19000 -13.5 7.7 005 29 15 4.5 2.5 | -13.4 7.9 360 31 16 6.5 3.5
18500 -13.0 8.6 005 28 15 4.0 2.2 | -12.4 9.7 360 30 16 6.8 3.8
18000 -12.4 9.7 360 28 15 4.1 2.3 | -11.4 11.5 355 29 15 6.8 3.7
17500 -11.5 11.3 360 27 14 7.8 4.3 | -10.3 13.5 355 28 14 8.2 4.5
17000 -10.4 13.3 355 27 14 7.5 4.1 | -8.5 16.7 350 26 14 8.1 4.5
16500 -9.2 15.4 350 26 13 8.4 4.6 | -7.3 18.9 345 26 13 8.5 4.7
16000 -8.0 17.6 350 26 13 8.6 4.7 | -6.0 21.2 340 26 13 8.6 4.7
15500 -6.7 19.9 345 25 13 8.5 4.7 | -4.9 23.2 340 26 13 7.9 4.3
15000 -5.5 22.1 345 25 13 8.5 4.6 | -3.7 25.3 335 24 13 7.9 4.4
14500 -4.3 24.3 340 25 13 8.5 4.7 | -2.6 27.3 330 23 12 8.2 4.5
14000 -2.4 27.7 340 25 13 8.5 4.7 | -1.4 29.5 330 21 11 8.3 4.6
13500 -1.2 29.8 340 25 13 8.6 4.7 | -0.1 31.8 325 20 10 8.2 4.5
13000 0.1 32.2 340 24 12 8.6 4.7 | 1.0 33.8 325 18 9 8.0 4.4
12500 1.3 34.3 340 23 12 8.4 4.6 | 2.2 36.0 320 17 9 8.1 4.4
12000 2.5 36.5 340 21 11 8.1 4.4 | 3.4 38.1 320 16 8 8.3 4.5
11500 3.7 38.7 340 19 10 7.9 4.3 | 4.6 40.3 320 14 7 8.5 4.7
11000 4.8 40.6 345 16 8 7.3 4.0 | 6.0 42.8 320 13 7 9.0 5.0
10500 5.9 42.6 345 13 7 3.9 2.2 | 7.4 45.3 320 11 6 6.1 3.4
10250 6.0 42.8 345 12 6 3.8 2.1 | 7.7 45.9 320 11 6 5.1 2.8
10000 6.6 43.9 345 11 6 10.3 5.7 | 8.3 46.9 320 10 5 10.1 5.6
9750 7.4 45.3 340 9 5 11.4 6.2 | 9.1 48.4 320 9 4 11.3 6.2
9500 8.1 46.6 340 7 4 8.8 4.8 | 9.9 49.8 315 7 4 9.1 5.0
9250 8.6 47.5 335 7 3 6.0 3.3 | 10.4 50.7 310 6 3 6.3 3.5
9000 9.2 48.6 335 6 3 9.8 5.4 | 10.9 51.6 305 5 3 7.5 4.1
8750 10.0 50.0 335 6 3 12.0 6.6 | 11.5 52.7 290 5 2 8.4 4.6
8500 10.8 51.4 335 6 3 10.0 5.5 | 12.1 53.8 275 4 2 7.4 4.1
8250 11.5 52.7 335 6 3 9.2 5.0 | 12.6 54.7 265 4 2 6.5 3.6
8000 12.2 54.0 335 6 3 9.9 5.4 | 13.1 55.6 255 4 2 7.6 4.2
7750 13.0 55.4 330 6 3 10.4 5.7 | 13.7 56.7 245 4 2 9.2 5.0
7500 13.8 56.8 330 5 3 10.0 5.5 | 14.4 57.9 245 4 2 10.0 5.5
7250 14.5 58.1 330 5 3 9.7 5.3 | 15.2 59.4 245 4 2 10.4 5.7
7000 15.2 59.4 330 5 3 10.3 5.7 | 15.9 60.6 245 4 2 10.0 5.5
6750 16.0 60.8 330 5 3 10.6 5.8 | 16.7 62.1 245 4 2 9.7 5.3
6500 16.8 62.2 330 5 3 10.3 5.6 | 17.4 63.3 245 4 2 10.0 5.5
6250 17.6 63.7 325 5 3 10.2 5.6 | 18.1 64.6 245 4 2 9.9 5.4
6000 18.3 64.9 325 5 3 10.8 5.9 | 18.9 66.0 245 4 2 10.4 5.7
5750 19.3 66.7 325 5 3 16.6 9.1 | 19.7 67.5 245 4 2 13.0 7.1
5500 20.8 69.4 320 4 2 24.2 13.3 | 20.8 69.4 235 4 2 15.5 8.5
________________________________________________________________________________
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.
CIN (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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- Pueblo, CO 81001-4856
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- Page last modified: May 1st, 2013 15:31 UTC