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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 181226
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0626 MDT Wednesday, April 18, 2018
This forecast is for Wednesday, April 18, 2018:
If the trigger temperature of 33.7 F/0.9 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 522 ft/min (2.7 m/s)
Maximum height of thermals.................. 15709 ft MSL (8095 ft AGL)
Forecast maximum temperature................... 54.0 F/12.7 C
Time of trigger temperature.................... 0830 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................. 14986 ft MSL (7372 ft AGL)
Thermal soaring outlook for Thursday 04/19..... Good
Wave Soaring Index............................. Not available
Remarks...
Effective May 18, 2018 this product will no longer be issued.
If you have any questions, please send email to:
jennifer.stark@noaa.gov
paul.wolyn@noaa.gov
Sunrise/Sunset.................... 06:17:58 / 19:39:10 MDT
Total possible sunshine........... 13 hr 21 min 12 sec (801 min 12 sec)
Altitude of sun at 12:58:34 MDT... 62.01 degrees
Upper air data from numerical model forecast valid on 04/18/2018 at 0600 MDT
Freezing level.................. Entire airmass below 32 F / 0 C
Convective condensation level... 23366 ft MSL (15752 ft AGL)
Lifted condensation level....... 20199 ft MSL (12585 ft AGL)
Lifted index.................... +7.3
K index......................... -41.7
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 -56.2 -69.2 255 30 15 1.3 0.7 M M M M M
45000 -54.2 -65.6 260 40 20 0.2 0.1 M M M M M
40000 -58.8 -73.8 265 45 23 -3.0 -1.6 M M M M M
38000 -57.8 -72.0 265 46 24 5.3 2.9 M M M M M
36000 -54.6 -66.3 265 45 23 5.3 2.9 M M M M M
34000 -51.2 -60.2 265 45 23 7.3 4.0 M M M M M
32000 -46.9 -52.4 270 42 22 7.3 4.0 M M M M M
30000 -42.5 -44.5 275 40 21 7.3 4.0 27.2 80.9 11.5 M M
29000 -40.3 -40.5 275 39 20 7.3 4.0 26.1 79.0 10.8 M M
28000 -38.1 -36.6 275 37 19 7.3 4.0 25.2 77.3 10.2 M M
27000 -35.9 -32.6 280 36 19 7.5 4.1 24.4 75.9 9.7 M M
26000 -33.5 -28.3 280 35 18 8.2 4.5 23.7 74.6 9.2 M M
25000 -31.0 -23.8 280 35 18 8.2 4.5 23.1 73.5 8.8 M M
24000 -28.0 -18.4 280 34 17 8.1 4.4 22.5 72.4 8.5 M M
23000 -25.6 -14.1 285 33 17 8.0 4.4 21.7 71.1 8.0 M M
22000 -23.2 -9.8 285 33 17 8.0 4.4 21.1 70.0 7.5 M M
21000 -20.8 -5.4 285 32 17 6.9 3.8 20.5 68.9 7.1 M M
20000 -18.8 -1.8 285 30 16 6.7 3.7 19.4 66.9 6.2 M M
19500 -17.8 -0.0 285 29 15 6.7 3.7 18.9 66.0 5.8 M M
19000 -16.8 1.8 285 28 14 6.7 3.7 18.4 65.1 5.4 M M
18500 -15.8 3.6 285 27 14 7.5 4.1 17.9 64.3 5.0 M M
18000 -14.6 5.7 280 25 13 8.0 4.4 17.6 63.7 4.8 M M
17500 -13.3 8.1 280 22 11 8.1 4.4 17.4 63.2 4.6 M M
17000 -12.7 9.1 280 20 10 1.1 0.6 16.4 61.6 3.8 M M
16500 -12.4 9.7 280 18 9 1.9 1.1 15.1 59.2 2.6 M M
16000 -12.4 9.7 285 16 8 -2.8 -1.5 13.6 56.4 1.2 M M
15500 -13.0 8.6 300 16 8 -3.7 -2.1 11.3 52.3 -0.9 523 2.7
15000 -13.5 7.7 310 17 9 -3.1 -1.7 9.1 48.3 -2.9 526 2.7
14500 -13.9 7.0 320 17 9 -2.2 -1.2 7.1 44.8 -4.8 522 2.6
14000 -14.2 6.4 330 18 9 -0.7 -0.4 5.2 41.3 -6.6 517 2.6
13500 -13.9 7.0 335 18 9 3.3 1.8 3.9 39.1 -7.8 492 2.5
13000 -13.4 7.9 340 18 9 3.8 2.1 2.9 37.2 -8.8 464 2.4
12500 -12.6 9.3 340 19 10 5.9 3.2 2.2 36.0 -9.5 424 2.2
12000 -11.9 10.6 340 19 10 5.5 3.0 1.5 34.7 -10.3 386 2.0
11750 -11.4 11.5 340 20 10 6.5 3.5 1.2 34.2 -10.6 366 1.9
11500 -10.9 12.4 340 20 10 6.8 3.7 1.0 33.7 -10.9 343 1.7
11250 -10.4 13.3 340 20 10 5.6 3.1 0.7 33.2 -11.1 322 1.6
11000 -10.1 13.8 340 20 11 5.0 2.8 0.3 32.6 -11.6 304 1.5
10750 -9.7 14.5 335 20 10 5.8 3.2 -0.0 32.0 -11.9 285 1.4
10500 -9.3 15.3 335 20 10 5.2 2.8 -0.3 31.4 -12.3 265 1.3
10250 -8.9 16.0 335 20 10 7.7 4.2 -0.6 30.8 -12.6 245 1.2
10000 -8.2 17.2 330 19 10 9.6 5.2 -0.7 30.8 -12.7 217 1.1
9750 -7.6 18.3 330 18 9 8.3 4.6 -0.8 30.6 -12.9 191 1.0
9500 -6.9 19.6 325 17 9 9.0 5.0 -0.8 30.5 -13.0 164 0.8
9250 -6.3 20.7 325 16 8 7.4 4.0 -0.9 30.3 -13.1 138 0.7
9000 -5.8 21.6 325 15 8 8.3 4.6 -1.1 29.9 -13.4 115 0.6
8750 -5.0 23.0 320 14 7 10.4 5.7 -1.1 30.0 -13.4 85 0.4
8500 -4.3 24.3 320 13 7 10.5 5.7 -1.1 30.0 -13.4 56 0.3
8250 -3.5 25.7 315 13 6 8.1 4.4 -1.1 30.1 -13.4 26 0.1
8000 -3.2 26.2 315 11 6 2.2 1.2 -1.4 29.4 -13.8 7 0.0
7750 -3.1 26.4 315 8 4 0.1 0.1 -2.1 28.2 -14.6 M M
7500 M M M M M M M M M M M M
7250 M M M M M M M M M M M M
7000 M M M M M M M M M M M M
6750 M M M M M M M M M M M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/18/2018 at 0900 MDT | 04/18/2018 at 1200 MDT
|
CAPE... 0.0 LI... +10.0 | CAPE... 0.0 LI... +8.9
CINH... 0.0 K Index... -32.1 | CINH... 0.0 K Index... -24.9
|
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 -56.7 -70.1 255 28 14 2.2 1.2 | -57.8 -72.0 255 29 15 2.2 1.2
45000 -53.4 -64.1 260 37 19 -1.7 -1.0 | -54.5 -66.1 260 37 19 -1.5 -0.8
40000 -57.3 -71.1 265 44 23 -2.6 -1.4 | -57.2 -71.0 260 40 21 -1.8 -1.0
38000 -56.9 -70.4 265 45 23 3.8 2.1 | -56.6 -69.9 260 41 21 3.4 1.9
36000 -54.6 -66.3 265 44 23 3.9 2.1 | -54.6 -66.3 265 41 21 3.4 1.9
34000 -51.5 -60.7 270 42 22 7.1 3.9 | -51.6 -60.9 265 40 20 6.8 3.7
32000 -47.2 -53.0 270 40 20 7.2 3.9 | -47.5 -53.5 270 38 19 6.9 3.8
30000 -42.9 -45.2 275 37 19 7.3 4.0 | -43.3 -45.9 275 36 18 7.5 4.1
29000 -40.7 -41.3 275 36 19 7.3 4.0 | -41.1 -42.0 275 35 18 7.5 4.1
28000 -38.5 -37.3 280 35 18 7.3 4.0 | -38.8 -37.8 280 35 18 7.5 4.1
27000 -36.3 -33.3 280 34 17 7.7 4.2 | -36.6 -33.9 280 34 18 8.7 4.8
26000 -33.9 -29.0 280 33 17 8.0 4.4 | -33.8 -28.8 280 35 18 9.1 5.0
25000 -31.5 -24.7 280 33 17 8.0 4.4 | -31.1 -24.0 280 35 18 9.1 5.0
24000 -29.1 -20.4 285 32 17 8.0 4.4 | -28.4 -19.1 280 35 18 8.6 4.7
23000 -26.8 -16.2 285 31 16 7.8 4.3 | -26.0 -14.8 285 34 17 7.8 4.3
22000 -24.4 -11.9 285 31 16 7.8 4.3 | -23.7 -10.7 285 32 17 7.8 4.3
21000 -22.1 -7.8 285 30 15 7.2 4.0 | -20.9 -5.6 285 30 15 6.8 3.8
20000 -19.6 -3.3 290 27 14 6.8 3.7 | -18.9 -2.0 290 27 14 6.9 3.8
19500 -18.6 -1.5 290 25 13 6.8 3.7 | -17.8 -0.0 290 26 13 6.9 3.8
19000 -17.5 0.5 290 24 12 6.8 3.7 | -16.8 1.8 290 25 13 7.1 3.9
18500 -16.5 2.3 290 23 12 7.1 3.9 | -15.9 3.4 290 23 12 4.9 2.7
18000 -15.4 4.3 285 21 11 7.1 3.9 | -15.1 4.8 290 22 11 5.1 2.8
17500 -14.4 6.1 285 19 10 6.8 3.7 | -14.4 6.1 290 20 10 5.1 2.8
17000 -13.4 7.9 285 17 9 6.1 3.4 | -13.6 7.5 290 18 9 5.2 2.8
16500 -12.5 9.5 280 16 8 6.9 3.8 | -12.8 9.0 290 17 9 5.1 2.8
16000 -12.0 10.4 285 14 7 -0.8 -0.4 | -12.1 10.2 290 15 8 4.1 2.3
15500 -12.0 10.4 290 13 7 0.1 0.0 | -11.5 11.3 295 14 7 4.6 2.5
15000 -12.1 10.2 300 13 7 -2.0 -1.1 | -11.0 12.2 295 13 7 0.4 0.2
14500 -12.5 9.5 310 13 7 -2.5 -1.4 | -11.0 12.2 300 12 6 0.3 0.2
14000 -12.9 8.8 320 14 7 -1.2 -0.6 | -11.0 12.2 305 12 6 -0.3 -0.1
13500 -12.9 8.8 325 14 7 -0.1 -0.1 | -11.1 12.0 310 11 6 -0.4 -0.2
13000 -12.9 8.8 335 15 7 1.2 0.7 | -11.1 12.0 315 11 6 1.0 0.6
12500 -12.6 9.3 340 15 8 2.9 1.6 | -10.8 12.6 325 10 5 2.6 1.4
12000 -12.1 10.2 345 15 8 4.6 2.5 | -10.3 13.5 330 9 5 5.8 3.2
11750 -11.7 10.9 345 15 8 6.6 3.6 | -9.8 14.4 330 8 4 8.1 4.5
11500 -11.2 11.8 345 15 8 6.3 3.5 | -9.2 15.4 335 7 4 7.4 4.1
11250 -10.7 12.7 345 15 8 7.5 4.1 | -8.7 16.3 340 6 3 7.3 4.0
11000 -10.1 13.8 350 15 8 7.7 4.2 | -8.1 17.4 340 6 3 9.4 5.1
10750 -9.6 14.7 345 15 8 7.4 4.1 | -7.3 18.9 340 6 3 10.8 5.9
10500 -9.1 15.6 345 14 7 6.7 3.7 | -6.6 20.1 340 6 3 10.9 6.0
10250 -8.5 16.7 340 14 7 10.0 5.5 | -5.8 21.6 340 6 3 9.1 5.0
10000 -7.6 18.3 340 13 7 11.6 6.4 | -5.2 22.6 340 6 3 8.8 4.8
9750 -6.9 19.6 335 12 6 9.3 5.1 | -4.4 24.1 340 6 3 10.5 5.8
9500 -6.2 20.8 335 11 6 10.4 5.7 | -3.6 25.5 340 6 3 10.2 5.6
9250 -5.4 22.3 330 11 5 8.3 4.6 | -2.9 26.8 345 6 3 9.6 5.3
9000 -4.9 23.2 330 10 5 9.2 5.1 | -2.2 28.0 345 6 3 9.6 5.3
8750 -4.0 24.8 330 10 5 11.7 6.4 | -1.4 29.5 345 6 3 10.3 5.7
8500 -3.2 26.2 325 10 5 11.2 6.1 | -0.7 30.7 345 6 3 10.3 5.7
8250 -2.3 27.9 325 9 5 10.9 6.0 | 0.1 32.2 345 6 3 11.6 6.4
8000 -1.4 29.5 325 9 5 15.3 8.4 | 1.2 34.2 345 6 3 19.9 10.9
7750 0.1 32.2 325 8 4 24.1 13.2 | 3.2 37.8 345 5 3 31.2 17.1
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
04/18/2018 at 1500 MDT | 04/18/2018 at 1800 MDT
|
CAPE... 0.0 LI... +8.8 | CAPE... 0.0 LI... +7.9
CINH... 0.0 K Index... -12.0 | CINH... 0.0 K Index... -21.0
|
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 -57.4 -71.3 255 29 15 1.8 1.0 | -57.9 -72.2 255 29 15 1.8 1.0
45000 -54.9 -66.8 260 36 19 -1.9 -1.0 | -55.2 -67.4 255 37 19 -2.5 -1.4
40000 -57.8 -72.0 260 42 21 -2.0 -1.1 | -59.0 -74.2 260 42 22 -2.5 -1.4
38000 -57.1 -70.8 260 42 21 3.6 2.0 | -58.0 -72.4 260 42 21 4.6 2.5
36000 -54.9 -66.8 260 40 21 3.7 2.0 | -55.3 -67.5 265 39 20 4.6 2.5
34000 -51.8 -61.2 265 38 20 7.0 3.8 | -51.6 -60.9 265 37 19 7.4 4.1
32000 -47.6 -53.7 265 36 18 7.0 3.9 | -47.1 -52.8 265 34 18 7.4 4.1
30000 -43.3 -45.9 265 33 17 7.7 4.2 | -42.7 -44.9 265 32 16 7.3 4.0
29000 -41.0 -41.8 265 33 17 7.7 4.2 | -40.6 -41.1 265 31 16 7.3 4.0
28000 -38.7 -37.7 265 32 17 7.7 4.2 | -38.4 -37.1 265 29 15 7.3 4.0
27000 -36.4 -33.5 265 31 16 8.7 4.7 | -36.2 -33.2 265 28 15 8.2 4.5
26000 -33.7 -28.7 270 31 16 8.8 4.8 | -33.7 -28.7 265 28 14 8.3 4.5
25000 -31.1 -24.0 270 31 16 8.8 4.8 | -31.2 -24.2 270 27 14 8.3 4.5
24000 -28.4 -19.1 270 31 16 8.5 4.7 | -28.7 -19.7 270 27 14 8.6 4.7
23000 -26.0 -14.8 275 30 15 8.2 4.5 | -26.1 -15.0 270 26 14 8.9 4.9
22000 -23.5 -10.3 275 29 15 8.3 4.5 | -23.4 -10.1 270 26 13 8.9 4.9
21000 -20.6 -5.1 280 27 14 6.6 3.6 | -20.3 -4.5 270 25 13 7.2 4.0
20000 -18.6 -1.5 280 25 13 6.7 3.7 | -18.1 -0.6 275 23 12 7.3 4.0
19500 -17.6 0.3 285 23 12 6.7 3.7 | -17.0 1.4 275 21 11 7.3 4.0
19000 -16.6 2.1 285 22 12 6.7 3.7 | -15.9 3.4 275 20 11 7.3 4.0
18500 -15.6 3.9 285 21 11 6.5 3.6 | -14.9 5.2 275 19 10 6.6 3.6
18000 -14.7 5.5 290 20 10 6.5 3.6 | -13.9 7.0 275 18 9 6.7 3.7
17500 -13.7 7.3 290 19 10 5.6 3.1 | -12.9 8.8 275 17 9 5.8 3.2
17000 -13.0 8.6 285 18 9 5.1 2.8 | -12.1 10.2 275 16 8 5.4 3.0
16500 -12.2 10.0 285 17 9 4.8 2.6 | -11.3 11.7 275 16 8 4.8 2.6
16000 -11.6 11.1 285 15 8 3.3 1.8 | -10.9 12.4 270 15 7 2.5 1.4
15500 -11.1 12.0 285 14 7 3.7 2.1 | -10.5 13.1 265 13 7 2.7 1.5
15000 -10.8 12.6 285 12 6 0.6 0.4 | -10.1 13.8 255 12 6 2.5 1.4
14500 -10.7 12.7 280 11 6 1.0 0.5 | -9.8 14.4 245 10 5 2.6 1.4
14000 -10.6 12.9 275 9 5 0.5 0.3 | -9.5 14.9 235 8 4 1.6 0.9
13500 -10.6 12.9 270 6 3 0.4 0.2 | -9.3 15.3 220 5 3 1.3 0.7
13000 -10.3 13.5 260 3 2 5.8 3.2 | -9.0 15.8 180 3 2 4.7 2.6
12500 -9.2 15.4 000 0 0 8.4 4.6 | -8.1 17.4 145 3 1 6.5 3.6
12000 -7.8 18.0 040 1 0 9.5 5.2 | -7.0 19.4 130 3 2 8.2 4.5
11750 -7.1 19.2 045 1 1 9.9 5.4 | -6.4 20.5 125 3 2 9.0 4.9
11500 -6.3 20.7 045 1 1 9.9 5.4 | -5.7 21.7 125 4 2 8.2 4.5
11250 -5.6 21.9 045 2 1 9.9 5.4 | -5.1 22.8 120 4 2 7.7 4.2
11000 -4.9 23.2 050 2 1 9.6 5.3 | -4.5 23.9 120 4 2 9.3 5.1
10750 -4.1 24.6 050 2 1 9.6 5.3 | -3.7 25.3 120 4 2 10.1 5.5
10500 -3.4 25.9 050 2 1 9.2 5.0 | -3.0 26.6 120 4 2 10.4 5.7
10250 -2.7 27.1 050 2 1 11.0 6.0 | -2.2 28.0 120 4 2 8.4 4.6
10000 -1.8 28.8 050 2 1 11.3 6.2 | -1.7 28.9 120 4 2 8.4 4.6
9750 -1.1 30.0 050 2 1 9.6 5.3 | -0.9 30.4 120 4 2 10.5 5.7
9500 -0.3 31.5 055 2 1 10.4 5.7 | -0.2 31.6 120 4 2 10.0 5.5
9250 0.4 32.7 055 2 1 9.0 4.9 | 0.6 33.1 120 4 2 9.9 5.4
9000 1.1 34.0 055 2 1 9.3 5.1 | 1.3 34.3 120 4 2 10.0 5.5
8750 1.8 35.2 055 2 1 10.8 5.9 | 2.1 35.8 120 4 2 10.4 5.7
8500 2.6 36.7 055 2 1 10.4 5.7 | 2.8 37.0 120 4 2 10.3 5.7
8250 3.4 38.1 055 3 1 11.8 6.5 | 3.6 38.5 120 4 2 10.0 5.5
8000 4.5 40.1 055 3 1 19.3 10.6 | 4.4 39.9 120 4 2 13.6 7.4
7750 6.4 43.5 055 3 1 29.2 16.0 | 5.7 42.3 120 4 2 20.3 11.1
7500 M M M M M M M | M M M M M M M
7250 M M M M M M M | M M M M M M M
7000 M M M M M M M | M M M M M M M
6750 M M M M M M M | M M M M M M M
________________________________________________________________________________
This product is issued twice per day, once by approximately 0630 MST/0730 MDT
(1330 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 Air Force Academy
in Colorado Springs, Colorado at
North Latitude: 38 deg 58 min 48.000 sec
West Longitude: 104 deg 49 min 12.000 sec
Elevation: 6572 feet (2003 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: Mar 8th, 2018 20:36 UTC