Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 180033
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1833 MDT Friday, May 17, 2013
This forecast is for Saturday, May 18, 2013:
If the trigger temperature of 74.6 F/23.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1311 ft/min (6.7 m/s)
Maximum height of thermals.................. 19761 ft MSL (14474 ft AGL)
Forecast maximum temperature................... 82.0 F/28.2 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1500 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................. 11404 ft MSL (6117 ft AGL)
Thermal soaring outlook for Sunday 05/19....... 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....................... 22049 ft MSL (16762 ft AGL)
Wave soaring outlook for Sunday 05/19.......... Poor
Remarks...
Sunrise/Sunset.................... 05:42:09 / 20:09:32 MDT
Total possible sunshine........... 14 hr 27 min 23 sec (867 min 23 sec)
Altitude of sun at 12:56:02 MDT... 69.92 degrees
Upper air data from numerical model forecast valid on 05/18/2013 at 0600 MDT
Freezing level.................. 13734 ft MSL (8447 ft AGL)
Convective condensation level... 18686 ft MSL (13399 ft AGL)
Lifted condensation level....... 18966 ft MSL (13679 ft AGL)
Lifted index.................... -1.6
K index......................... +12.1
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 -57.6 -71.7 250 18 9 1.0 0.6 M M M M M
45000 -56.5 -69.7 230 28 14 -2.5 -1.4 M M M M M
40000 -60.4 -76.7 210 45 23 -2.2 -1.2 M M M M M
38000 -57.6 -71.7 205 48 25 7.2 3.9 M M M M M
36000 -53.3 -63.9 205 49 25 7.2 3.9 M M M M M
34000 -48.3 -54.9 205 49 25 7.7 4.2 M M M M M
32000 -43.6 -46.5 200 49 25 7.7 4.2 M M M M M
30000 -39.2 -38.6 200 49 25 7.2 4.0 36.0 96.9 6.2 M M
29000 -37.0 -34.6 200 48 25 7.2 4.0 35.0 95.0 5.5 M M
28000 -34.8 -30.6 200 47 24 7.2 4.0 34.1 93.4 4.9 M M
27000 -32.6 -26.7 205 47 24 7.3 4.0 33.2 91.8 4.2 M M
26000 -30.5 -22.9 205 47 24 7.3 4.0 32.2 89.9 3.5 M M
25000 -28.3 -18.9 205 47 24 7.3 4.0 31.3 88.3 2.8 M M
24000 -26.0 -14.8 210 48 25 8.0 4.4 30.5 86.9 2.2 M M
23000 -23.7 -10.7 210 49 25 7.9 4.4 29.8 85.6 1.5 M M
22000 -21.3 -6.3 210 51 26 8.0 4.4 29.1 84.5 1.0 M M
21000 -18.9 -2.0 210 51 26 8.6 4.7 28.6 83.5 0.5 M M
20000 -16.4 2.5 205 49 25 8.7 4.8 28.2 82.7 0.1 M M
19500 -15.1 4.8 205 48 25 8.7 4.8 28.0 82.4 -0.1 1393 7.1
19000 -13.8 7.2 205 47 24 8.7 4.8 27.9 82.2 -0.2 1340 6.8
18500 -12.6 9.3 205 46 24 8.5 4.6 27.7 81.8 -0.4 1287 6.5
18000 -11.3 11.7 205 44 23 8.5 4.7 27.5 81.4 -0.6 1234 6.3
17500 -10.1 13.8 210 42 22 7.9 4.3 27.2 81.0 -0.8 1182 6.0
17000 -8.9 16.0 210 39 20 7.5 4.1 26.8 80.3 -1.2 1134 5.8
16500 -7.2 19.0 215 36 18 8.3 4.6 26.3 79.4 -1.7 1061 5.4
16000 -5.9 21.4 215 33 17 8.6 4.7 26.1 79.0 -1.9 1007 5.1
15500 -4.6 23.7 220 31 16 8.8 4.8 25.9 78.7 -2.0 953 4.8
15000 -3.3 26.1 220 30 15 9.0 5.0 25.8 78.4 -2.2 897 4.6
14500 -1.9 28.6 225 29 15 9.0 5.0 25.7 78.2 -2.3 841 4.3
14000 -0.5 31.1 225 28 14 9.2 5.1 25.6 78.0 -2.3 785 4.0
13500 0.9 33.6 225 26 13 9.2 5.1 25.5 77.9 -2.4 728 3.7
13000 2.3 36.1 225 24 12 9.2 5.0 25.4 77.7 -2.5 672 3.4
12500 3.7 38.7 225 22 11 9.2 5.1 25.3 77.5 -2.6 615 3.1
12000 5.0 41.0 225 20 10 8.3 4.6 25.2 77.3 -2.7 561 2.8
11500 6.2 43.2 225 17 9 8.3 4.6 24.9 76.9 -3.0 509 2.6
11000 7.4 45.3 220 15 8 7.5 4.1 24.7 76.4 -3.3 458 2.3
10500 8.5 47.3 215 12 6 6.6 3.6 24.3 75.7 -3.6 410 2.1
10250 9.1 48.4 215 11 6 10.8 5.9 24.1 75.4 -3.8 386 2.0
10000 10.1 50.2 210 9 5 11.4 6.2 24.4 75.8 -3.6 350 1.8
9750 10.7 51.3 210 8 4 7.5 4.1 24.2 75.6 -3.7 324 1.6
9500 11.3 52.3 200 6 3 8.7 4.8 24.1 75.4 -3.9 298 1.5
9250 11.9 53.4 190 4 2 7.7 4.2 24.0 75.2 -4.0 273 1.4
9000 12.4 54.3 185 3 1 6.8 3.7 23.8 74.9 -4.2 250 1.3
8750 12.9 55.2 185 1 1 6.8 3.7 23.6 74.5 -4.5 228 1.2
8500 13.4 56.1 000 0 0 6.8 3.8 23.4 74.0 -4.7 205 1.0
8250 13.9 57.0 010 2 1 6.8 3.7 23.1 73.6 -5.0 183 0.9
8000 14.4 57.9 340 4 2 6.3 3.4 22.9 73.2 -5.2 161 0.8
7750 14.8 58.6 330 6 3 5.7 3.1 22.6 72.7 -5.5 141 0.7
7500 15.2 59.4 330 7 4 5.6 3.1 22.3 72.1 -5.9 121 0.6
7250 15.6 60.1 325 9 5 6.0 3.3 22.0 71.6 -6.2 101 0.5
7000 16.1 61.0 325 10 5 5.7 3.1 21.7 71.0 -6.5 80 0.4
6750 16.5 61.7 330 10 5 6.9 3.8 21.4 70.5 -6.8 60 0.3
6500 16.9 62.4 330 11 5 0.5 0.3 21.1 69.9 -7.2 41 0.2
6250 16.4 61.5 330 10 5 -10.4 -5.7 19.9 67.8 -8.4 47 0.2
6000 15.5 59.9 325 9 4 -11.2 -6.1 18.3 64.9 -10.1 67 0.3
5750 14.6 58.3 315 7 4 -14.3 -7.8 16.6 62.0 -11.7 87 0.4
5500 12.5 54.5 285 6 3 -45.3 -24.9 14.0 57.1 -14.5 142 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/18/2013 at 0900 MDT | 05/18/2013 at 1200 MDT
|
K index... +13.7 LI... +1.9 | K index... +14.4 LI... -0.3
CAPE... 0.0 CIN... -0.5 | CAPE... +65.8 CIN... -89.9
|
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 -56.8 -70.2 250 16 8 2.1 1.1 | -56.5 -69.7 250 15 8 2.4 1.3
45000 -54.3 -65.7 240 26 14 -2.6 -1.4 | -53.4 -64.1 250 20 10 -2.1 -1.2
40000 -58.3 -72.9 205 48 25 -2.5 -1.4 | -56.6 -69.9 210 47 24 -2.1 -1.2
38000 -56.7 -70.1 200 52 27 5.0 2.7 | -55.6 -68.1 205 53 27 3.6 2.0
36000 -53.7 -64.7 200 54 28 5.0 2.7 | -53.4 -64.1 200 55 29 3.6 2.0
34000 -49.4 -56.9 200 54 28 8.1 4.5 | -49.9 -57.8 200 57 29 7.5 4.1
32000 -44.5 -48.1 200 52 27 8.1 4.5 | -45.5 -49.9 200 56 29 7.5 4.1
30000 -40.0 -40.0 205 51 26 7.0 3.8 | -40.8 -41.4 200 53 27 8.2 4.5
29000 -37.9 -36.2 205 50 26 7.0 3.8 | -38.3 -36.9 200 51 26 8.2 4.5
28000 -35.8 -32.4 205 49 25 7.0 3.8 | -35.8 -32.4 200 49 25 8.2 4.5
27000 -33.6 -28.5 205 49 25 7.7 4.2 | -33.6 -28.5 200 47 24 6.1 3.3
26000 -31.3 -24.3 205 48 25 7.7 4.2 | -31.7 -25.1 200 45 23 6.2 3.4
25000 -29.0 -20.2 205 48 25 7.7 4.2 | -29.9 -21.8 200 43 22 6.2 3.4
24000 -26.7 -16.1 205 47 24 7.5 4.1 | -27.9 -18.2 200 41 21 8.5 4.7
23000 -24.4 -11.9 205 48 25 7.6 4.2 | -25.3 -13.5 200 40 21 8.5 4.7
22000 -22.2 -8.0 205 48 25 7.7 4.2 | -22.8 -9.0 200 38 20 8.5 4.7
21000 -19.8 -3.6 205 46 24 8.6 4.7 | -20.2 -4.4 200 37 19 8.3 4.6
20000 -17.3 0.9 205 43 22 8.6 4.7 | -17.8 -0.0 200 35 18 8.4 4.6
19500 -16.0 3.2 210 41 21 8.7 4.8 | -16.5 2.3 200 34 17 8.4 4.6
19000 -14.7 5.5 210 39 20 8.7 4.8 | -15.3 4.5 200 33 17 8.3 4.6
18500 -13.5 7.7 210 37 19 8.7 4.8 | -14.0 6.8 200 32 16 9.4 5.2
18000 -12.2 10.0 210 36 18 8.7 4.8 | -12.6 9.3 200 30 16 9.3 5.1
17500 -10.9 12.4 210 34 18 8.6 4.7 | -11.2 11.8 200 29 15 8.8 4.8
17000 -9.6 14.7 210 33 17 8.5 4.7 | -9.3 15.3 200 26 13 8.3 4.5
16500 -7.7 18.1 210 30 16 8.5 4.6 | -8.1 17.4 200 24 12 8.1 4.4
16000 -6.4 20.5 215 29 15 8.4 4.6 | -6.9 19.6 200 22 11 8.0 4.4
15500 -5.1 22.8 215 27 14 8.3 4.5 | -5.7 21.7 200 20 10 8.1 4.5
15000 -3.9 25.0 215 25 13 8.0 4.4 | -4.4 24.1 200 18 9 8.6 4.7
14500 -2.7 27.1 220 23 12 8.0 4.4 | -3.1 26.4 205 17 9 8.5 4.7
14000 -1.4 29.5 220 22 11 9.0 5.0 | -1.8 28.8 205 16 8 9.1 5.0
13500 -0.1 31.8 220 21 11 8.9 4.9 | -0.5 31.1 205 15 8 9.1 5.0
13000 1.3 34.3 215 20 10 9.5 5.2 | 0.9 33.6 205 14 7 9.3 5.1
12500 2.7 36.9 215 19 10 9.6 5.3 | 2.3 36.1 205 13 7 9.3 5.1
12000 4.1 39.4 210 17 9 8.5 4.7 | 3.6 38.5 205 12 6 8.1 4.5
11500 5.4 41.7 210 15 8 8.5 4.7 | 4.8 40.6 205 11 6 8.1 4.4
11000 6.6 43.9 200 13 7 7.3 4.0 | 5.9 42.6 200 10 5 7.2 4.0
10500 7.6 45.7 195 10 5 6.7 3.7 | 7.0 44.6 190 9 5 6.6 3.6
10250 8.2 46.8 190 9 5 9.1 5.0 | 7.5 45.5 185 8 4 9.1 5.0
10000 8.9 48.0 175 7 4 7.5 4.1 | 8.2 46.8 180 8 4 9.0 4.9
9750 9.2 48.6 165 6 3 4.1 2.2 | 8.7 47.7 180 7 4 6.3 3.5
9500 9.5 49.1 150 5 2 4.9 2.7 | 9.2 48.6 175 6 3 7.0 3.9
9250 9.9 49.8 125 4 2 5.1 2.8 | 9.7 49.5 165 5 3 6.8 3.7
9000 10.3 50.5 110 3 2 6.3 3.5 | 10.3 50.5 165 4 2 7.4 4.0
8750 10.8 51.4 090 3 1 6.7 3.7 | 10.8 51.4 165 2 1 7.9 4.3
8500 11.3 52.3 070 3 1 6.7 3.7 | 11.3 52.3 175 1 1 7.5 4.1
8250 11.7 53.1 055 3 2 6.2 3.4 | 11.9 53.4 000 0 0 8.6 4.7
8000 12.2 54.0 040 4 2 5.7 3.1 | 12.6 54.7 340 1 0 9.8 5.4
7750 12.6 54.7 030 4 2 6.0 3.3 | 13.3 55.9 345 1 0 9.6 5.3
7500 13.0 55.4 025 5 3 6.0 3.3 | 14.0 57.2 345 1 0 9.7 5.3
7250 13.5 56.3 020 6 3 5.9 3.2 | 14.7 58.5 345 1 0 10.0 5.5
7000 13.9 57.0 015 7 3 5.7 3.1 | 15.4 59.7 340 1 0 10.1 5.6
6750 14.3 57.7 010 7 4 5.2 2.9 | 16.2 61.2 340 1 0 9.6 5.2
6500 14.6 58.3 005 7 4 4.7 2.6 | 16.9 62.4 340 1 1 10.1 5.5
6250 14.9 58.8 005 6 3 4.6 2.5 | 17.7 63.9 335 1 1 11.2 6.2
6000 15.2 59.4 005 4 2 4.2 2.3 | 18.5 65.3 335 1 1 11.1 6.1
5750 15.5 59.9 360 3 1 6.8 3.7 | 19.4 66.9 330 1 1 12.1 6.7
5500 16.3 61.3 355 1 1 14.9 8.2 | 20.5 68.9 325 1 1 19.6 10.8
05/18/2013 at 1500 MDT | 05/18/2013 at 1800 MDT
|
K index... +23.5 LI... -1.3 | K index... +22.2 LI... -1.2
CAPE... +169.0 CIN... -3.5 | CAPE... +194.7 CIN... -30.6
|
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 -56.0 -68.8 250 16 8 2.5 1.4 | -55.9 -68.6 250 11 6 2.8 1.5
45000 -52.8 -63.0 245 21 11 -1.7 -0.9 | -52.2 -62.0 215 12 6 -0.8 -0.5
40000 -55.3 -67.5 215 44 22 -1.4 -0.8 | -53.3 -63.9 220 33 17 -0.7 -0.4
38000 -54.3 -65.7 210 48 24 2.7 1.5 | -52.7 -62.9 215 39 20 1.7 0.9
36000 -52.7 -62.9 205 50 26 2.7 1.5 | -51.7 -61.1 215 43 22 1.7 0.9
34000 -50.2 -58.4 205 51 26 6.7 3.7 | -49.9 -57.8 210 46 24 5.7 3.1
32000 -46.2 -51.2 205 51 26 6.6 3.6 | -46.4 -51.5 215 44 23 5.8 3.2
30000 -41.9 -43.4 205 51 26 8.4 4.6 | -42.5 -44.5 215 41 21 8.1 4.5
29000 -39.4 -38.9 205 49 25 8.4 4.6 | -40.1 -40.2 215 38 20 8.2 4.5
28000 -36.3 -33.3 205 47 24 8.4 4.6 | -37.0 -34.6 220 35 18 8.2 4.5
27000 -33.8 -28.8 205 45 23 8.1 4.4 | -34.6 -30.3 220 33 17 8.0 4.4
26000 -31.4 -24.5 205 42 22 8.1 4.4 | -32.2 -26.0 220 31 16 8.0 4.4
25000 -29.0 -20.2 205 39 20 8.1 4.4 | -29.9 -21.8 220 30 15 8.0 4.4
24000 -26.6 -15.9 205 36 19 7.9 4.3 | -27.5 -17.5 220 28 15 7.9 4.3
23000 -24.3 -11.7 205 35 18 7.9 4.3 | -25.1 -13.2 215 27 14 7.9 4.3
22000 -22.0 -7.6 205 33 17 7.9 4.3 | -22.8 -9.0 215 26 13 7.9 4.3
21000 -19.7 -3.5 200 31 16 7.5 4.1 | -20.4 -4.7 210 25 13 8.1 4.5
20000 -17.4 0.7 200 29 15 7.5 4.1 | -18.0 -0.4 205 25 13 8.1 4.5
19500 -16.3 2.7 195 28 15 7.5 4.1 | -16.8 1.8 205 25 13 8.1 4.5
19000 -15.2 4.6 195 28 14 7.5 4.1 | -15.6 3.9 205 24 13 8.1 4.5
18500 -14.1 6.6 195 26 14 7.5 4.1 | -14.4 6.1 200 24 12 8.2 4.5
18000 -13.0 8.6 195 25 13 7.5 4.1 | -13.2 8.2 200 24 12 8.3 4.5
17500 -11.9 10.6 195 23 12 7.4 4.1 | -12.0 10.4 200 23 12 8.3 4.5
17000 -10.8 12.6 195 22 11 7.3 4.0 | -10.8 12.6 200 23 12 8.3 4.6
16500 -9.7 14.5 195 21 11 7.3 4.0 | -9.6 14.7 200 22 11 8.3 4.6
16000 -8.6 16.5 200 20 10 7.9 4.4 | -8.3 17.1 200 21 11 8.1 4.5
15500 -7.5 18.5 200 19 10 7.8 4.3 | -7.2 19.0 200 20 10 8.1 4.5
15000 -6.2 20.8 200 18 9 9.3 5.1 | -5.9 21.4 200 18 10 9.0 4.9
14500 -4.8 23.4 205 17 9 9.5 5.2 | -3.9 25.0 195 16 8 9.1 5.0
14000 -2.7 27.1 205 15 8 10.0 5.5 | -2.5 27.5 195 15 8 9.5 5.2
13500 -1.2 29.8 205 13 7 10.0 5.5 | -1.1 30.0 200 13 7 9.4 5.2
13000 0.2 32.4 205 12 6 9.4 5.1 | 0.3 32.5 200 12 6 9.5 5.2
12500 1.6 34.9 205 10 5 9.5 5.2 | 1.7 35.1 205 11 6 9.5 5.2
12000 2.9 37.2 210 7 4 8.4 4.6 | 3.1 37.6 210 10 5 9.4 5.2
11500 4.1 39.4 215 5 3 8.4 4.6 | 4.5 40.1 210 9 5 9.4 5.2
11000 5.4 41.7 230 4 2 8.3 4.5 | 5.9 42.6 215 9 4 8.6 4.7
10500 6.6 43.9 245 3 2 8.0 4.4 | 7.1 44.8 220 8 4 8.1 4.5
10250 7.2 45.0 250 3 2 11.5 6.3 | 7.8 46.0 225 7 4 10.6 5.8
10000 8.2 46.8 265 3 1 11.9 6.5 | 8.6 47.5 230 7 4 10.6 5.8
9750 8.9 48.0 270 3 2 9.4 5.2 | 9.3 48.7 230 6 3 8.3 4.6
9500 9.7 49.5 275 3 2 10.1 5.6 | 9.9 49.8 235 5 3 9.1 5.0
9250 10.4 50.7 280 3 2 9.7 5.3 | 10.6 51.1 245 5 2 8.4 4.6
9000 11.1 52.0 285 3 2 9.6 5.3 | 11.2 52.2 260 4 2 7.5 4.1
8750 11.9 53.4 285 3 2 9.9 5.4 | 11.7 53.1 280 4 2 7.3 4.0
8500 12.6 54.7 285 3 2 9.4 5.2 | 12.2 54.0 300 4 2 7.0 3.8
8250 13.3 55.9 285 4 2 11.1 6.1 | 12.8 55.0 320 5 2 8.5 4.6
8000 14.2 57.6 290 4 2 10.9 6.0 | 13.4 56.1 330 6 3 9.4 5.2
7750 14.9 58.8 290 4 2 9.0 4.9 | 14.1 57.4 335 7 4 8.5 4.7
7500 15.6 60.1 295 4 2 9.3 5.1 | 14.7 58.5 340 8 4 8.4 4.6
7250 16.3 61.3 295 4 2 10.3 5.7 | 15.3 59.5 340 9 5 9.7 5.3
7000 17.1 62.8 295 4 2 10.7 5.9 | 16.1 61.0 340 10 5 10.5 5.8
6750 17.8 64.0 295 4 2 9.1 5.0 | 16.8 62.2 340 10 5 9.5 5.2
6500 18.5 65.3 295 4 2 9.4 5.1 | 17.5 63.5 340 10 5 9.4 5.2
6250 19.3 66.7 295 4 2 11.0 6.0 | 18.2 64.8 340 10 5 9.8 5.4
6000 20.1 68.2 300 5 2 11.6 6.3 | 19.0 66.2 340 10 5 10.0 5.5
5750 20.9 69.6 300 5 2 10.3 5.7 | 19.7 67.5 340 10 5 9.9 5.4
5500 21.8 71.2 300 5 2 14.5 8.0 | 20.4 68.7 340 9 5 10.7 5.9
________________________________________________________________________________
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.
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: May 1st, 2013 15:32 UTC