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Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
000
UXUS97 KBOU 240036
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
1836 MDT Thursday, May 23, 2013
This forecast is for Friday, May 24, 2013:
If the trigger temperature of 76.3 F/24.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1233 ft/min (6.3 m/s)
Maximum height of thermals.................. 18423 ft MSL (13136 ft AGL)
Forecast maximum temperature................... 85.0 F/29.9 C
Time of trigger temperature.................... 1100 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................. 11385 ft MSL (6097 ft AGL)
Thermal soaring outlook for Saturday 05/25..... Excellent
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... Little change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak NVA
Potential height of wave....................... 19329 ft MSL (14042 ft AGL)
Wave soaring outlook for Saturday 05/25........ Fair
Remarks... Upper level ridge axis over western kansas and nebraska with dry and
moderate southwest flow aloft across colorado.
Sunrise/Sunset.................... 05:37:44 / 20:14:48 MDT
Total possible sunshine........... 14 hr 37 min 4 sec (877 min 4 sec)
Altitude of sun at 12:56:28 MDT... 71.11 degrees
Upper air data from numerical model forecast valid on 05/24/2013 at 0600 MDT
Freezing level.................. 14725 ft MSL (9438 ft AGL)
Convective condensation level... 15393 ft MSL (10106 ft AGL)
Lifted condensation level....... 15852 ft MSL (10564 ft AGL)
Lifted index.................... -4.6
K index......................... +6.5
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 -61.0 -77.8 250 23 12 -1.3 -0.7 M M M M M
45000 -62.7 -80.9 240 36 18 0.1 0.0 M M M M M
40000 -62.6 -80.7 225 34 18 -0.6 -0.3 M M M M M
38000 -58.2 -72.8 225 31 16 8.2 4.5 M M M M M
36000 -53.3 -63.9 225 27 14 8.2 4.5 M M M M M
34000 -48.1 -54.6 225 24 12 9.0 4.9 M M M M M
32000 -42.0 -43.6 230 22 11 9.0 5.0 M M M M M
30000 -36.8 -34.2 235 22 11 8.4 4.6 38.3 100.9 6.7 M M
29000 -34.3 -29.7 240 23 12 8.4 4.6 37.8 100.0 6.4 M M
28000 -31.8 -25.2 245 24 12 8.5 4.7 37.4 99.3 6.2 M M
27000 -29.4 -20.9 245 26 13 7.6 4.2 36.6 97.9 5.6 M M
26000 -27.1 -16.8 245 29 15 7.6 4.2 35.7 96.3 5.0 M M
25000 -24.9 -12.8 250 32 16 7.6 4.2 35.0 95.0 4.5 M M
24000 -22.6 -8.7 245 34 18 7.6 4.2 34.2 93.6 3.9 M M
23000 -20.3 -4.5 245 37 19 7.6 4.2 33.4 92.2 3.3 M M
22000 -18.0 -0.4 240 40 20 7.7 4.2 32.7 90.9 2.7 M M
21000 -15.9 3.4 235 42 22 6.9 3.8 31.8 89.2 1.9 M M
20000 -13.8 7.2 230 44 23 6.9 3.8 30.7 87.3 1.0 M M
19500 -12.8 9.0 230 45 23 7.0 3.9 30.3 86.5 0.6 M M
19000 -11.8 10.8 230 46 24 7.8 4.3 29.9 85.7 0.2 M M
18500 -10.5 13.1 225 44 23 9.1 5.0 29.7 85.5 0.0 M M
18000 -9.1 15.6 225 43 22 9.2 5.1 29.6 85.3 -0.1 1197 6.1
17500 -7.8 18.0 225 41 21 8.8 4.8 29.5 85.0 -0.2 1142 5.8
17000 -6.5 20.3 225 39 20 8.8 4.8 29.3 84.7 -0.4 1088 5.5
16500 -5.2 22.6 220 37 19 9.0 4.9 29.1 84.5 -0.5 1034 5.3
16000 -3.1 26.4 225 36 19 9.2 5.0 29.0 84.2 -0.7 950 4.8
15500 -1.8 28.8 225 36 18 8.8 4.8 28.9 84.0 -0.8 895 4.5
15000 -0.5 31.1 225 34 18 8.6 4.7 28.7 83.6 -0.9 841 4.3
14500 0.9 33.6 225 33 17 8.0 4.4 28.5 83.3 -1.1 787 4.0
14000 1.9 35.4 225 28 15 6.9 3.8 28.1 82.5 -1.5 740 3.8
13500 3.0 37.4 220 23 12 7.1 3.9 27.6 81.7 -1.9 694 3.5
13000 4.1 39.4 220 20 10 8.1 4.4 27.3 81.1 -2.3 645 3.3
12500 5.3 41.5 215 16 8 8.0 4.4 27.0 80.6 -2.6 595 3.0
12000 6.5 43.7 215 15 8 9.0 4.9 26.8 80.2 -2.8 543 2.8
11500 7.8 46.0 220 15 8 9.0 5.0 26.6 80.0 -3.0 489 2.5
11000 9.0 48.2 225 17 9 7.8 4.3 26.4 79.6 -3.2 437 2.2
10500 10.2 50.4 230 19 10 8.6 4.7 26.1 79.1 -3.5 388 2.0
10250 10.8 51.4 230 20 10 5.5 3.0 26.0 78.8 -3.7 363 1.8
10000 11.1 52.0 230 21 11 5.7 3.1 25.6 78.0 -4.2 347 1.8
9750 11.7 53.1 230 23 12 8.8 4.8 25.4 77.8 -4.3 322 1.6
9500 12.2 54.0 230 26 13 8.3 4.6 25.3 77.6 -4.5 297 1.5
9250 12.8 55.0 230 28 14 6.3 3.5 25.2 77.3 -4.7 273 1.4
9000 13.1 55.6 230 28 14 3.5 1.9 24.8 76.6 -5.1 257 1.3
8750 13.3 55.9 230 28 14 3.6 2.0 24.3 75.7 -5.7 244 1.2
8500 13.4 56.1 230 28 15 3.7 2.0 23.8 74.8 -6.3 232 1.2
8250 13.6 56.5 225 28 15 1.8 1.0 23.3 73.9 -6.9 220 1.1
8000 13.6 56.5 225 28 15 1.3 0.7 22.6 72.7 -7.6 213 1.1
7750 13.7 56.7 225 29 15 2.7 1.5 22.0 71.6 -8.3 203 1.0
7500 13.8 56.8 225 29 15 2.6 1.4 21.5 70.7 -8.9 191 1.0
7250 13.9 57.0 220 29 15 2.2 1.2 20.9 69.6 -9.5 180 0.9
7000 14.0 57.2 220 29 15 2.1 1.1 20.3 68.6 -10.2 170 0.9
6750 14.1 57.4 215 29 15 2.3 1.2 19.7 67.5 -10.9 160 0.8
6500 14.2 57.6 215 29 15 0.4 0.2 19.1 66.5 -11.6 150 0.8
6250 14.1 57.4 210 26 13 -1.4 -0.8 18.3 65.0 -12.4 147 0.7
6000 13.9 57.0 210 23 12 -0.2 -0.1 17.5 63.5 -13.3 143 0.7
5750 13.8 56.8 205 20 10 -5.2 -2.8 16.7 62.0 -14.2 140 0.7
5500 12.9 55.2 200 14 7 -16.3 -8.9 15.2 59.3 -15.8 159 0.8
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/24/2013 at 0900 MDT | 05/24/2013 at 1200 MDT
|
K index... -8.7 LI... -0.2 | K index... -3.2 LI... +0.8
CAPE... +110.6 CIN... -137.9 | CAPE... +63.5 CIN... -107.3
|
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 -61.2 -78.2 255 27 14 -0.6 -0.4 | -60.8 -77.4 255 24 13 -0.3 -0.2
45000 -62.1 -79.8 240 43 22 -0.3 -0.2 | -61.3 -78.3 255 40 20 -0.7 -0.4
40000 -62.6 -80.7 220 33 17 -1.4 -0.8 | -62.4 -80.3 235 41 21 -1.6 -0.9
38000 -58.4 -73.1 215 30 16 8.0 4.4 | -58.6 -73.5 230 38 20 7.5 4.1
36000 -53.7 -64.7 210 28 14 8.0 4.4 | -54.2 -65.6 220 35 18 7.5 4.1
34000 -48.7 -55.7 215 26 13 8.6 4.7 | -49.3 -56.7 220 32 17 8.6 4.7
32000 -42.9 -45.2 220 24 12 8.6 4.7 | -43.5 -46.3 225 29 15 8.6 4.7
30000 -37.7 -35.9 230 25 13 8.6 4.7 | -38.4 -37.1 230 27 14 8.6 4.7
29000 -35.1 -31.2 235 26 13 8.6 4.7 | -35.8 -32.4 230 27 14 8.6 4.7
28000 -32.5 -26.5 240 27 14 8.7 4.8 | -33.2 -27.8 235 26 14 8.6 4.7
27000 -30.0 -22.0 240 28 14 8.2 4.5 | -30.6 -23.1 235 27 14 8.6 4.7
26000 -27.6 -17.7 240 30 15 8.2 4.5 | -28.1 -18.6 235 27 14 8.6 4.7
25000 -25.1 -13.2 240 31 16 8.2 4.5 | -25.5 -13.9 240 28 15 8.5 4.7
24000 -22.8 -9.0 240 32 17 7.6 4.2 | -23.1 -9.6 240 29 15 7.9 4.3
23000 -20.5 -4.9 240 34 17 7.6 4.2 | -20.7 -5.3 240 30 16 7.8 4.3
22000 -18.2 -0.8 240 35 18 7.6 4.2 | -18.3 -0.9 240 32 16 7.8 4.3
21000 -16.0 3.2 235 36 19 7.4 4.1 | -15.9 3.4 240 33 17 8.1 4.5
20000 -13.7 7.3 235 37 19 7.4 4.1 | -13.5 7.7 235 34 18 8.1 4.5
19500 -12.6 9.3 230 38 19 7.5 4.1 | -12.3 9.9 235 35 18 8.2 4.5
19000 -11.5 11.3 230 38 20 8.1 4.4 | -11.1 12.0 235 35 18 8.2 4.5
18500 -10.2 13.6 230 38 20 8.9 4.9 | -9.8 14.4 235 36 18 8.3 4.6
18000 -8.9 16.0 230 38 20 8.9 4.9 | -8.6 16.5 235 36 19 8.3 4.6
17500 -7.6 18.3 230 38 20 8.7 4.8 | -7.3 18.9 235 36 19 8.5 4.7
17000 -6.3 20.7 230 38 20 8.7 4.8 | -6.0 21.2 235 36 19 8.5 4.7
16500 -5.0 23.0 230 38 20 8.4 4.6 | -4.2 24.4 235 36 19 7.8 4.3
16000 -3.1 26.4 230 37 19 8.1 4.5 | -3.0 26.6 235 36 19 7.9 4.3
15500 -1.9 28.6 230 36 19 7.9 4.3 | -1.8 28.8 235 36 19 7.6 4.2
15000 -0.8 30.6 235 35 18 7.8 4.3 | -0.7 30.7 235 35 18 7.5 4.1
14500 0.4 32.7 235 34 18 7.7 4.2 | 0.4 32.7 235 35 18 7.2 3.9
14000 1.5 34.7 235 32 17 7.5 4.1 | 1.4 34.5 235 33 17 6.8 3.7
13500 2.6 36.7 230 30 16 7.4 4.1 | 2.4 36.3 235 31 16 6.7 3.7
13000 3.7 38.7 230 27 14 6.9 3.8 | 3.3 37.9 235 28 15 6.6 3.6
12500 4.7 40.5 230 24 13 7.0 3.8 | 4.3 39.7 230 26 13 6.7 3.7
12000 5.8 42.4 230 22 11 7.8 4.3 | 5.3 41.5 230 24 12 7.4 4.1
11500 6.9 44.4 230 21 11 7.7 4.2 | 6.4 43.5 225 22 11 7.3 4.0
11000 8.1 46.6 230 19 10 8.3 4.6 | 7.6 45.7 220 21 11 8.5 4.7
10500 9.3 48.7 235 19 10 7.2 3.9 | 8.9 48.0 215 20 10 5.3 2.9
10250 9.8 49.6 235 18 9 5.4 3.0 | 9.1 48.4 210 20 10 5.9 3.2
10000 10.2 50.4 240 17 9 7.7 4.2 | 9.8 49.6 210 18 9 10.9 6.0
9750 10.9 51.6 240 16 8 9.3 5.1 | 10.5 50.9 210 17 9 10.1 5.5
9500 11.5 52.7 245 15 8 8.8 4.8 | 11.2 52.2 205 15 8 10.0 5.5
9250 12.1 53.8 250 14 7 7.0 3.8 | 11.9 53.4 205 14 7 8.0 4.4
9000 12.6 54.7 250 13 7 7.2 4.0 | 12.4 54.3 205 13 7 8.3 4.6
8750 13.2 55.8 255 12 6 9.0 4.9 | 13.1 55.6 200 11 6 9.7 5.3
8500 13.8 56.8 260 11 6 7.9 4.3 | 13.7 56.7 195 10 5 9.4 5.2
8250 14.3 57.7 265 11 6 6.0 3.3 | 14.4 57.9 190 8 4 9.4 5.1
8000 14.6 58.3 270 11 5 4.7 2.6 | 15.1 59.2 185 7 4 9.5 5.2
7750 15.0 59.0 275 10 5 4.9 2.7 | 15.8 60.4 185 6 3 9.6 5.2
7500 15.3 59.5 280 10 5 3.0 1.6 | 16.5 61.7 185 6 3 9.9 5.4
7250 15.3 59.5 275 9 5 0.6 0.3 | 17.3 63.1 185 5 3 10.5 5.7
7000 15.2 59.4 270 9 4 0.6 0.3 | 18.0 64.4 185 5 3 10.2 5.6
6750 15.2 59.4 260 8 4 0.1 0.0 | 18.8 65.8 185 5 2 9.6 5.3
6500 15.1 59.2 245 7 4 4.3 2.4 | 19.5 67.1 185 4 2 10.4 5.7
6250 15.6 60.1 245 6 3 8.1 4.4 | 20.3 68.5 185 4 2 11.7 6.4
6000 16.0 60.8 240 5 3 6.3 3.5 | 21.1 70.0 190 4 2 9.8 5.4
5750 16.5 61.7 240 4 2 10.7 5.9 | 21.9 71.4 190 3 2 13.4 7.4
5500 17.6 63.7 235 4 2 20.9 11.5 | 23.3 73.9 190 3 2 25.9 14.2
05/24/2013 at 1500 MDT | 05/24/2013 at 1800 MDT
|
K index... +12.8 LI... +1.0 | K index... +13.7 LI... +0.2
CAPE... +0.2 CIN... -15.7 | CAPE... +24.8 CIN... -31.1
|
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 -60.8 -77.4 250 27 14 1.3 0.7 | -61.0 -77.8 255 30 15 1.2 0.7
45000 -59.5 -75.1 255 41 21 -2.2 -1.2 | -59.7 -75.5 260 41 21 -1.9 -1.0
40000 -63.2 -81.8 240 49 25 -0.9 -0.5 | -62.6 -80.7 245 48 25 -2.9 -1.6
38000 -58.8 -73.8 235 46 24 8.1 4.5 | -58.7 -73.7 245 46 24 7.8 4.3
36000 -53.9 -65.0 235 42 22 8.1 4.5 | -54.1 -65.4 245 43 22 7.8 4.3
34000 -49.0 -56.2 235 38 20 8.3 4.6 | -48.5 -55.3 240 39 20 8.5 4.7
32000 -44.0 -47.2 230 33 17 8.3 4.6 | -43.4 -46.1 240 37 19 8.5 4.7
30000 -38.9 -38.0 230 29 15 8.8 4.8 | -38.4 -37.1 235 33 17 8.4 4.6
29000 -36.3 -33.3 230 28 14 8.8 4.8 | -35.8 -32.4 235 31 16 8.4 4.6
28000 -33.6 -28.5 230 26 14 8.8 4.8 | -33.3 -27.9 230 29 15 8.3 4.6
27000 -30.4 -22.7 235 27 14 8.7 4.8 | -30.7 -23.3 235 29 15 8.7 4.8
26000 -27.7 -17.9 235 28 14 8.7 4.8 | -28.1 -18.6 240 31 16 8.7 4.8
25000 -25.1 -13.2 240 29 15 8.8 4.8 | -25.5 -13.9 245 33 17 8.7 4.8
24000 -22.7 -8.9 240 31 16 7.7 4.2 | -23.2 -9.8 250 34 17 7.0 3.8
23000 -20.4 -4.7 245 33 17 7.7 4.2 | -21.1 -6.0 250 33 17 7.0 3.8
22000 -18.1 -0.6 245 36 18 7.7 4.2 | -19.1 -2.4 250 32 17 6.9 3.8
21000 -15.9 3.4 245 36 18 7.6 4.1 | -16.8 1.8 250 30 16 8.3 4.6
20000 -13.7 7.3 245 35 18 7.6 4.2 | -14.3 6.3 245 28 14 8.4 4.6
19500 -12.5 9.5 245 35 18 7.6 4.2 | -13.1 8.4 245 27 14 8.4 4.6
19000 -11.4 11.5 250 34 18 7.9 4.3 | -11.8 10.8 245 25 13 8.7 4.8
18500 -10.2 13.6 250 33 17 8.0 4.4 | -10.5 13.1 240 25 13 9.0 4.9
18000 -9.1 15.6 250 31 16 8.0 4.4 | -9.2 15.4 240 25 13 9.0 4.9
17500 -7.9 17.8 245 30 16 8.1 4.4 | -7.8 18.0 235 25 13 9.1 5.0
17000 -6.7 19.9 245 29 15 8.1 4.4 | -5.8 21.6 230 25 13 9.0 5.0
16500 -5.5 22.1 245 28 14 8.3 4.6 | -4.4 24.1 230 26 13 9.7 5.3
16000 -4.3 24.3 240 27 14 8.4 4.6 | -3.0 26.6 225 26 13 9.6 5.3
15500 -3.0 26.6 235 27 14 8.5 4.7 | -1.5 29.3 225 26 13 9.4 5.2
15000 -1.7 28.9 230 26 14 8.8 4.8 | -0.1 31.8 225 25 13 9.4 5.1
14500 -0.4 31.3 225 26 13 8.8 4.8 | 1.3 34.3 220 25 13 9.6 5.2
14000 1.5 34.7 220 25 13 8.9 4.9 | 2.7 36.9 220 25 13 9.8 5.4
13500 2.8 37.0 215 24 12 9.1 5.0 | 4.2 39.6 220 24 13 9.7 5.3
13000 4.2 39.6 215 23 12 9.4 5.1 | 5.6 42.1 215 24 12 9.2 5.1
12500 5.6 42.1 215 22 11 9.4 5.2 | 7.0 44.6 215 23 12 9.2 5.1
12000 7.0 44.6 210 21 11 9.8 5.4 | 8.4 47.1 215 22 11 9.1 5.0
11500 8.5 47.3 210 20 10 9.7 5.3 | 9.7 49.5 215 21 11 9.2 5.0
11000 9.8 49.6 210 19 10 8.4 4.6 | 11.0 51.8 210 20 10 8.4 4.6
10500 11.0 51.8 210 18 9 11.6 6.4 | 12.2 54.0 210 18 9 11.7 6.4
10250 12.1 53.8 210 18 9 12.6 6.9 | 13.3 55.9 210 18 9 12.3 6.8
10000 12.8 55.0 210 17 9 9.0 4.9 | 14.0 57.2 210 17 9 8.5 4.7
9750 13.5 56.3 210 17 9 10.0 5.5 | 14.7 58.5 210 16 8 9.5 5.2
9500 14.2 57.6 210 17 9 9.4 5.1 | 15.3 59.5 210 15 8 9.2 5.0
9250 14.9 58.8 210 16 8 9.1 5.0 | 16.0 60.8 215 15 8 9.3 5.1
9000 15.6 60.1 210 16 8 10.0 5.5 | 16.7 62.1 215 14 7 9.7 5.3
8750 16.4 61.5 210 16 8 10.5 5.8 | 17.5 63.5 215 13 7 10.0 5.5
8500 17.2 63.0 210 15 8 10.4 5.7 | 18.2 64.8 215 12 6 9.9 5.4
8250 18.0 64.4 210 15 8 10.9 6.0 | 18.9 66.0 220 12 6 10.4 5.7
8000 18.8 65.8 210 15 8 10.2 5.6 | 19.7 67.5 220 11 6 9.7 5.3
7750 19.5 67.1 210 15 7 9.2 5.1 | 20.4 68.7 220 10 5 8.7 4.8
7500 20.2 68.4 210 14 7 9.9 5.4 | 21.1 70.0 225 10 5 9.5 5.2
7250 21.0 69.8 215 14 7 10.5 5.7 | 21.8 71.2 225 9 5 10.7 5.9
7000 21.7 71.1 215 14 7 10.3 5.7 | 22.6 72.7 230 9 5 10.6 5.8
6750 22.5 72.5 215 13 7 9.7 5.3 | 23.4 74.1 230 9 4 9.1 5.0
6500 23.2 73.8 215 13 7 10.2 5.6 | 24.0 75.2 230 8 4 9.8 5.4
6250 24.0 75.2 215 13 7 11.2 6.1 | 24.8 76.6 235 8 4 11.2 6.1
6000 24.8 76.6 215 12 6 10.1 5.5 | 25.6 78.1 235 8 4 10.6 5.8
5750 25.6 78.1 215 12 6 12.5 6.9 | 26.4 79.5 240 7 4 9.9 5.4
5500 26.8 80.2 215 11 6 21.8 12.0 | 27.1 80.8 240 6 3 11.7 6.4
________________________________________________________________________________
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 15:31 UTC