Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 121247
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0647 MDT Wednesday, June 12, 2013
This forecast is for Wednesday, June 12, 2013:
If the trigger temperature of 80.4 F/26.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1208 ft/min (6.1 m/s)
Maximum height of thermals.................. 18700 ft MSL (13415 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 C
Time of trigger temperature.................... 0900 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................. 15360 ft MSL (10075 ft AGL)
Thermal soaring outlook for Thursday 06/13..... 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)................ Weak NVA
Potential height of wave....................... 20314 ft MSL (15029 ft AGL)
Wave soaring outlook for Thursday 06/13........ Poor
Remarks...
Sunrise/Sunset.................... 05:31:02 / 20:27:40 MDT
Total possible sunshine........... 14 hr 56 min 38 sec (896 min 38 sec)
Altitude of sun at 12:59:30 MDT... 73.40 degrees
Upper air data from rawinsonde observation taken on 06/12/2013 at 0600 MDT
Freezing level.................. 15609 ft MSL (10324 ft AGL)
Convective condensation level... 21880 ft MSL (16595 ft AGL)
Lifted condensation level....... 21262 ft MSL (15977 ft AGL)
Lifted index.................... +0.9
K index......................... +7.2
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 -62.7 -80.9 230 27 14 -3.5 -1.9 88.4 191.1 31.7 M M
45000 -55.4 -67.7 275 36 19 -1.6 -0.9 76.3 169.3 26.4 M M
40000 -57.3 -71.1 280 59 31 2.3 1.2 50.5 122.9 11.1 M M
38000 -54.0 -65.2 275 62 32 7.6 4.1 46.6 115.9 8.7 M M
36000 -48.7 -55.7 270 65 34 9.1 5.0 45.8 114.5 8.4 M M
34000 -43.2 -45.8 270 70 36 9.0 4.9 45.3 113.5 8.2 M M
32000 -37.9 -36.2 260 61 31 7.2 3.9 43.5 110.3 7.1 M M
30000 -32.7 -26.9 260 52 27 8.8 4.9 42.8 109.0 6.7 M M
29000 -30.1 -22.2 260 51 26 8.9 4.9 42.2 108.0 6.4 M M
28000 -27.4 -17.3 265 51 26 8.9 4.9 41.8 107.2 6.1 M M
27000 -24.8 -12.6 265 51 26 8.8 4.9 41.5 106.7 5.9 M M
26000 -22.1 -7.8 270 50 26 6.2 3.4 41.3 106.3 5.8 M M
25000 -21.0 -5.8 270 50 26 3.9 2.1 39.0 102.2 4.0 M M
24000 -19.1 -2.4 275 45 23 8.8 4.9 37.7 99.9 3.0 M M
23000 -16.5 2.3 275 40 21 7.7 4.2 37.4 99.3 2.8 M M
22000 -14.3 6.3 275 43 22 7.1 3.9 36.5 97.7 2.1 M M
21000 -12.2 10.0 270 46 24 7.2 4.0 35.6 96.0 1.3 M M
20000 -9.7 14.5 270 50 26 9.5 5.2 35.1 95.2 0.9 M M
19500 -8.6 16.5 275 46 24 5.2 2.9 34.7 94.5 0.6 M M
19000 -7.6 18.3 275 43 22 8.6 4.7 34.2 93.6 0.2 M M
18500 -6.3 20.7 280 42 21 8.6 4.7 34.0 93.2 -0.0 1196 6.1
18000 -5.0 23.0 280 40 21 8.6 4.7 33.8 92.8 -0.2 1143 5.8
17500 -3.7 25.3 285 38 20 8.5 4.7 33.6 92.4 -0.4 1090 5.5
17000 -2.4 27.7 285 37 19 8.0 4.4 33.4 92.1 -0.6 1037 5.3
16500 -1.5 29.3 290 35 18 5.1 2.8 32.8 91.0 -1.1 995 5.1
16000 -0.4 31.3 295 34 17 5.4 3.0 31.7 89.0 -2.2 939 4.8
15500 0.3 32.5 290 32 16 5.5 3.0 31.0 87.7 -3.0 902 4.6
15000 1.2 34.2 285 30 16 7.5 4.1 30.3 86.6 -3.6 862 4.4
14500 2.4 36.3 280 29 15 8.5 4.6 30.1 86.3 -3.8 809 4.1
14000 3.7 38.7 275 28 14 8.5 4.7 30.0 85.9 -4.0 756 3.8
13500 5.0 41.0 275 26 13 8.5 4.7 29.7 85.5 -4.2 703 3.6
13000 6.3 43.3 270 24 12 8.5 4.7 29.5 85.2 -4.4 650 3.3
12500 7.5 45.5 270 22 11 8.5 4.7 29.4 84.9 -4.6 597 3.0
12000 8.8 47.8 265 20 10 8.5 4.7 29.2 84.5 -4.8 544 2.8
11500 10.1 50.2 275 20 10 8.5 4.7 29.0 84.1 -5.1 491 2.5
11000 11.4 52.5 280 20 10 8.6 4.7 28.7 83.7 -5.3 438 2.2
10500 12.7 54.9 290 21 11 8.8 4.8 28.5 83.4 -5.5 384 2.0
10250 13.4 56.1 290 20 10 10.4 5.7 28.5 83.4 -5.5 356 1.8
10000 14.1 57.4 295 18 9 7.5 4.1 28.5 83.4 -5.5 326 1.7
9750 14.5 58.1 295 16 8 3.8 2.1 28.2 82.7 -5.9 308 1.6
9500 14.8 58.6 300 14 7 4.3 2.3 27.7 81.9 -6.4 291 1.5
9250 15.1 59.2 300 13 6 3.6 2.0 27.3 81.1 -6.8 275 1.4
9000 15.4 59.7 305 11 6 5.6 3.1 26.8 80.3 -7.2 258 1.3
8750 15.9 60.6 305 10 5 7.7 4.2 26.6 80.0 -7.5 235 1.2
8500 16.5 61.7 310 9 5 7.2 4.0 26.5 79.6 -7.7 211 1.1
8250 17.0 62.6 310 9 4 7.3 4.0 26.3 79.3 -7.9 188 1.0
8000 17.5 63.5 315 8 4 7.3 4.0 26.1 79.0 -8.1 164 0.8
7750 18.1 64.6 320 7 4 7.3 4.0 25.9 78.6 -8.3 141 0.7
7500 18.6 65.5 320 6 3 7.3 4.0 25.7 78.3 -8.5 117 0.6
7250 19.1 66.4 325 5 3 7.4 4.0 25.5 78.0 -8.7 94 0.5
7000 19.7 67.5 335 4 2 7.2 3.9 25.4 77.7 -8.9 70 0.4
6750 20.2 68.4 335 2 1 7.8 4.3 25.2 77.3 -9.1 47 0.2
6500 20.7 69.3 335 1 0 5.4 3.0 25.0 77.0 -9.4 24 0.1
6250 21.0 69.8 155 1 1 3.9 2.2 24.5 76.2 -9.9 8 0.0
6000 21.2 70.2 155 3 1 0.8 0.4 24.1 75.3 -10.4 M M
5750 20.8 69.4 170 3 1 -11.3 -6.2 23.0 73.3 -11.5 M M
5500 19.2 66.6 185 3 1 -32.4 -17.8 20.7 69.2 -14.0 41 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/12/2013 at 0900 MDT | 06/12/2013 at 1200 MDT
|
K index... +3.1 LI... +5.2 | K index... +10.3 LI... +4.1
CAPE... 0.0 CIN... -3.8 | CAPE... 0.0 CIN... -0.4
|
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 -62.4 -80.3 255 32 16 2.1 1.2 | -62.6 -80.7 250 23 12 2.3 1.3
45000 -59.3 -74.7 260 43 22 1.6 0.9 | -59.3 -74.7 255 36 18 1.6 0.9
40000 -56.1 -69.0 270 58 30 7.3 4.0 | -56.2 -69.2 260 58 30 7.3 4.0
38000 -51.9 -61.4 275 56 29 7.1 3.9 | -51.8 -61.2 265 54 28 7.2 4.0
36000 -47.6 -53.7 275 54 28 7.1 3.9 | -47.5 -53.5 270 50 26 7.2 3.9
34000 -42.9 -45.2 270 49 25 8.1 4.4 | -42.6 -44.7 270 49 25 8.3 4.5
32000 -37.4 -35.3 265 45 23 8.1 4.4 | -37.0 -34.6 270 47 24 8.7 4.8
30000 -33.1 -27.6 265 42 22 7.1 3.9 | -32.8 -27.0 270 45 23 6.9 3.8
29000 -30.9 -23.6 265 41 21 7.1 3.9 | -30.7 -23.3 270 44 23 6.9 3.8
28000 -28.8 -19.8 270 40 20 7.5 4.1 | -28.6 -19.5 270 43 22 7.7 4.2
27000 -26.5 -15.7 270 39 20 7.6 4.2 | -26.2 -15.2 265 40 20 7.8 4.3
26000 -24.3 -11.7 270 39 20 7.6 4.2 | -23.9 -11.0 265 37 19 7.8 4.3
25000 -22.0 -7.6 275 38 20 7.9 4.3 | -21.5 -6.7 265 34 17 8.1 4.5
24000 -19.4 -2.9 275 39 20 8.9 4.9 | -18.9 -2.0 260 36 18 8.8 4.8
23000 -16.7 1.9 270 40 21 8.9 4.9 | -16.3 2.7 260 38 19 8.8 4.8
22000 -14.0 6.8 270 41 21 8.7 4.8 | -13.7 7.3 255 40 21 8.6 4.7
21000 -11.5 11.3 270 42 22 8.6 4.7 | -11.1 12.0 260 41 21 8.5 4.7
20000 -8.9 16.0 265 44 23 8.6 4.7 | -8.6 16.5 260 41 21 8.5 4.7
19500 -7.6 18.3 265 44 23 8.6 4.7 | -7.3 18.9 260 42 21 8.5 4.7
19000 -6.4 20.5 265 44 23 7.9 4.3 | -6.1 21.0 260 41 21 7.6 4.2
18500 -5.2 22.6 265 43 22 7.9 4.3 | -5.0 23.0 260 40 21 7.7 4.2
18000 -4.0 24.8 265 41 21 7.4 4.1 | -3.8 25.2 260 39 20 7.1 3.9
17500 -3.0 26.6 265 38 20 7.0 3.8 | -2.9 26.8 265 36 18 6.6 3.6
17000 -2.0 28.4 265 35 18 7.0 3.8 | -1.9 28.6 265 33 17 6.6 3.6
16500 -1.0 30.2 265 32 17 6.0 3.3 | -1.1 30.0 265 30 16 5.7 3.1
16000 0.3 32.5 260 28 14 6.3 3.5 | 0.2 32.4 260 26 14 6.2 3.4
15500 1.3 34.3 260 25 13 7.8 4.3 | 1.2 34.2 260 25 13 8.0 4.4
15000 2.5 36.5 260 23 12 7.7 4.2 | 2.4 36.3 255 24 12 7.9 4.3
14500 3.6 38.5 255 21 11 8.0 4.4 | 3.6 38.5 255 24 12 8.8 4.8
14000 4.8 40.6 255 19 10 8.0 4.4 | 4.9 40.8 250 23 12 8.7 4.8
13500 6.0 42.8 250 17 9 7.6 4.1 | 6.2 43.2 245 23 12 8.5 4.7
13000 7.0 44.6 250 16 8 7.4 4.1 | 7.5 45.5 240 23 12 8.5 4.6
12500 8.1 46.6 245 15 8 7.0 3.8 | 8.8 47.8 240 22 12 8.2 4.5
12000 9.1 48.4 240 14 7 6.6 3.6 | 10.0 50.0 235 22 11 8.0 4.4
11500 10.1 50.2 235 12 6 5.6 3.1 | 11.2 52.2 230 21 11 7.1 3.9
11000 10.8 51.4 235 10 5 4.4 2.4 | 12.0 53.6 220 18 9 5.9 3.2
10500 11.5 52.7 235 7 4 2.4 1.3 | 12.9 55.2 215 16 8 2.4 1.3
10250 11.6 52.9 235 7 4 3.4 1.9 | 12.9 55.2 210 15 8 0.9 0.5
10000 12.0 53.6 235 5 3 7.3 4.0 | 13.2 55.8 205 12 6 4.8 2.6
9750 12.6 54.7 240 3 2 7.1 3.9 | 13.4 56.1 195 9 5 3.6 2.0
9500 13.1 55.6 260 1 1 5.8 3.2 | 13.7 56.7 175 7 4 4.8 2.7
9250 13.4 56.1 330 1 1 4.4 2.4 | 14.1 57.4 165 7 3 6.3 3.5
9000 13.8 56.8 010 2 1 6.9 3.8 | 14.6 58.3 160 6 3 8.4 4.6
8750 14.3 57.7 020 4 2 8.3 4.5 | 15.2 59.4 155 6 3 9.7 5.3
8500 14.9 58.8 020 5 3 8.1 4.5 | 15.9 60.6 150 6 3 9.8 5.4
8250 15.5 59.9 025 5 3 8.4 4.6 | 16.7 62.1 150 6 3 10.2 5.6
8000 16.1 61.0 025 5 3 8.3 4.6 | 17.4 63.3 150 6 3 10.0 5.5
7750 16.6 61.9 030 5 2 7.4 4.1 | 18.2 64.8 150 6 3 10.0 5.5
7500 17.1 62.8 035 4 2 5.5 3.0 | 18.9 66.0 150 5 3 10.1 5.5
7250 17.4 63.3 040 4 2 5.0 2.8 | 19.7 67.5 150 5 3 9.9 5.5
7000 17.7 63.9 045 4 2 4.5 2.4 | 20.5 68.9 150 5 3 10.5 5.8
6750 18.0 64.4 055 3 2 5.4 3.0 | 21.2 70.2 145 5 3 10.8 5.9
6500 18.5 65.3 050 2 1 7.5 4.1 | 22.0 71.6 145 5 3 10.3 5.7
6250 19.1 66.4 035 1 0 7.1 3.9 | 22.8 73.0 145 5 2 10.0 5.5
6000 19.7 67.5 290 1 0 8.2 4.5 | 23.5 74.3 145 5 2 11.2 6.1
5750 20.5 68.9 275 1 1 13.4 7.3 | 24.6 76.3 150 4 2 17.8 9.8
5500 21.7 71.1 245 1 1 18.5 10.1 | 26.2 79.2 150 5 2 25.2 13.8
06/12/2013 at 1500 MDT | 06/12/2013 at 1800 MDT
|
K index... +18.9 LI... +0.2 | K index... +21.2 LI... -0.1
CAPE... +1.1 CIN... -50.2 | CAPE... +124.9 CIN... -52.1
|
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 -62.0 -79.6 260 22 11 2.1 1.1 | -62.7 -80.9 245 18 9 1.8 1.0
45000 -59.2 -74.6 260 38 20 1.0 0.6 | -59.9 -75.8 255 32 16 2.0 1.1
40000 -56.7 -70.1 260 56 29 7.8 4.3 | -56.0 -68.8 270 57 29 7.5 4.1
38000 -51.9 -61.4 265 55 28 7.9 4.3 | -51.4 -60.5 270 57 29 7.7 4.2
36000 -47.2 -53.0 265 53 28 7.9 4.3 | -46.7 -52.1 265 56 29 7.7 4.2
34000 -42.3 -44.1 265 50 26 8.2 4.5 | -42.0 -43.6 265 53 28 7.9 4.3
32000 -36.7 -34.1 270 46 24 8.6 4.7 | -36.7 -34.1 260 50 26 8.3 4.5
30000 -32.1 -25.8 270 45 23 7.6 4.2 | -32.2 -26.0 260 48 25 7.5 4.1
29000 -29.8 -21.6 265 45 23 7.6 4.2 | -30.0 -22.0 265 48 24 7.5 4.1
28000 -27.5 -17.5 265 44 23 7.9 4.3 | -27.7 -17.9 265 47 24 7.8 4.3
27000 -25.1 -13.2 265 43 22 7.9 4.4 | -25.4 -13.7 260 46 24 7.8 4.3
26000 -22.7 -8.9 260 42 22 7.9 4.4 | -23.1 -9.6 260 45 23 7.8 4.3
25000 -20.4 -4.7 255 41 21 7.8 4.3 | -20.7 -5.3 260 44 23 7.5 4.1
24000 -18.1 -0.6 255 41 21 7.5 4.1 | -18.6 -1.5 260 41 21 7.1 3.9
23000 -15.9 3.4 255 41 21 7.5 4.1 | -16.6 2.1 255 38 19 7.1 3.9
22000 -13.7 7.3 255 41 21 7.2 3.9 | -14.5 5.9 255 34 18 7.9 4.3
21000 -11.7 10.9 260 37 19 6.9 3.8 | -12.0 10.4 255 32 16 8.5 4.7
20000 -9.7 14.5 260 34 17 6.9 3.8 | -9.5 14.9 250 29 15 8.6 4.7
19500 -8.7 16.3 260 32 16 7.0 3.8 | -8.3 17.1 250 28 15 8.6 4.7
19000 -7.6 18.3 260 31 16 8.9 4.9 | -6.9 19.6 250 27 14 9.5 5.2
18500 -6.3 20.7 260 30 15 8.8 4.8 | -5.5 22.1 250 27 14 9.5 5.2
18000 -5.0 23.0 260 29 15 9.1 5.0 | -4.1 24.6 250 26 13 9.3 5.1
17500 -3.6 25.5 255 29 15 9.4 5.1 | -2.7 27.1 245 24 12 9.2 5.0
17000 -2.2 28.0 255 28 15 9.4 5.1 | -1.3 29.7 240 22 11 9.2 5.0
16500 -0.9 30.4 250 28 14 9.1 5.0 | -0.0 32.0 240 20 11 8.7 4.8
16000 1.2 34.2 250 27 14 9.0 4.9 | 1.9 35.4 230 18 10 8.6 4.7
15500 2.5 36.5 245 26 13 8.6 4.7 | 3.2 37.8 225 17 9 8.3 4.6
15000 3.8 38.8 240 25 13 8.7 4.8 | 4.4 39.9 215 15 8 8.3 4.6
14500 5.0 41.0 235 24 12 7.8 4.3 | 5.7 42.3 205 14 7 8.7 4.8
14000 6.2 43.2 230 23 12 7.9 4.3 | 6.9 44.4 195 14 7 8.7 4.8
13500 7.3 45.1 220 23 12 7.7 4.2 | 8.2 46.8 185 13 7 8.7 4.8
13000 8.5 47.3 210 21 11 7.7 4.2 | 9.5 49.1 180 13 7 8.7 4.8
12500 9.6 49.3 200 20 10 7.5 4.1 | 10.8 51.4 175 13 7 9.1 5.0
12000 10.6 51.1 185 18 9 7.5 4.1 | 12.2 54.0 175 13 7 9.4 5.1
11500 11.7 53.1 170 16 8 8.0 4.4 | 13.6 56.5 170 13 6 9.5 5.2
11000 13.0 55.4 165 15 8 8.4 4.6 | 15.0 59.0 170 12 6 9.4 5.1
10500 14.3 57.7 160 14 7 5.1 2.8 | 16.5 61.7 170 11 6 6.2 3.4
10250 14.6 58.3 160 14 7 6.9 3.8 | 16.8 62.2 170 11 6 7.4 4.0
10000 15.4 59.7 160 14 7 12.7 7.0 | 17.7 63.9 170 11 6 12.5 6.8
9750 16.3 61.3 160 14 7 11.8 6.5 | 18.5 65.3 170 11 5 11.7 6.4
9500 17.1 62.8 160 14 7 9.6 5.3 | 19.4 66.9 170 10 5 9.8 5.4
9250 17.7 63.9 155 14 7 8.0 4.4 | 20.0 68.0 170 10 5 8.6 4.7
9000 18.4 65.1 155 13 7 10.5 5.8 | 20.7 69.3 170 10 5 10.4 5.7
8750 19.2 66.6 155 13 7 10.8 5.9 | 21.5 70.7 170 9 5 10.5 5.7
8500 20.0 68.0 155 13 7 10.6 5.8 | 22.3 72.1 170 9 5 10.2 5.6
8250 20.8 69.4 155 13 7 10.6 5.8 | 23.0 73.4 170 9 4 9.9 5.4
8000 21.6 70.9 155 13 6 10.1 5.5 | 23.8 74.8 170 8 4 10.1 5.5
7750 22.3 72.1 155 12 6 9.6 5.3 | 24.5 76.1 170 8 4 10.2 5.6
7500 23.0 73.4 155 12 6 10.1 5.6 | 25.3 77.5 170 8 4 10.1 5.5
7250 23.8 74.8 155 12 6 10.5 5.8 | 26.0 78.8 170 7 4 10.1 5.6
7000 24.6 76.3 155 12 6 9.8 5.4 | 26.8 80.2 170 7 4 9.7 5.3
6750 25.3 77.5 155 12 6 9.7 5.3 | 27.5 81.5 170 7 4 9.2 5.0
6500 26.1 79.0 155 11 6 10.7 5.9 | 28.2 82.8 175 7 3 9.8 5.4
6250 26.9 80.4 150 11 6 12.0 6.6 | 28.9 84.0 170 6 3 10.3 5.7
6000 27.8 82.0 150 11 5 8.6 4.7 | 29.7 85.5 170 6 3 9.7 5.3
5750 28.5 83.3 150 10 5 13.7 7.5 | 30.5 86.9 175 6 3 12.1 6.6
5500 30.1 86.2 150 9 5 31.8 17.5 | 31.6 88.9 170 5 2 17.9 9.8
________________________________________________________________________________
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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- Page last modified: Jun 3rd, 2013 15:31 UTC