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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 171206
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0606 MDT Wednesday, April 17, 2024
This forecast is for the Air Force Academy for Wednesday, April 17, 2024:
If the trigger temperature of 54.5 F/12.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1532 ft/min (7.8 m/s)
Maximum height of thermals.................. 23610 ft MSL (16006 ft AGL)
Forecast maximum temperature................... 71.0 F/22.1 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................. 19725 ft MSL (12120 ft AGL)
Thermal soaring outlook for Thursday 04/18..... Fair
Wave Soaring Index............................. Not available
Remarks... There could be some cirrus that gets in the way of things this am.
Sunrise/Sunset.................... 06:18:32 / 19:38:47 MDT
Total possible sunshine........... 13 hr 20 min 15 sec (800 min 15 sec)
Altitude of sun at 12:58:40 MDT... 61.87 degrees
Upper air data from numerical model forecast valid on 04/17/2024 at 0600 MDT
Freezing level.................. 11895 ft MSL (4291 ft AGL)
Convective condensation level... 17151 ft MSL (9547 ft AGL)
Lifted condensation level....... 19347 ft MSL (11743 ft AGL)
Lifted index.................... -2.7
K index......................... -7.8
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 -57.5 -71.5 270 49 25 1.9 1.0 M M M M M
45000 -55.0 -67.0 275 59 30 -2.6 -1.4 M M M M M
40000 -58.3 -72.9 270 41 21 -2.2 -1.2 M M M M M
38000 -56.4 -69.5 275 38 20 5.7 3.1 M M M M M
36000 -52.9 -63.2 280 38 19 5.7 3.1 M M M M M
34000 -49.2 -56.6 280 38 20 6.9 3.8 M M M M M
32000 -45.1 -49.2 280 40 20 6.9 3.8 M M M M M
30000 -40.9 -41.6 275 41 21 7.5 4.1 27.9 82.2 4.8 M M
29000 -38.6 -37.5 275 41 21 7.5 4.1 27.0 80.5 4.1 M M
28000 -36.4 -33.5 275 41 21 7.5 4.1 26.2 79.1 3.5 M M
27000 -34.1 -29.4 270 41 21 7.0 3.8 25.4 77.8 3.0 M M
26000 -32.1 -25.8 270 41 21 6.9 3.8 24.2 75.6 2.0 M M
25000 -30.0 -22.0 270 40 20 6.9 3.8 23.2 73.8 1.2 M M
24000 -28.0 -18.4 270 39 20 7.0 3.8 22.3 72.2 0.5 M M
23000 -25.9 -14.6 270 37 19 7.0 3.9 21.2 70.2 -0.5 1485 7.5
22000 -23.2 -9.8 270 35 18 7.0 3.9 20.1 68.1 -1.5 1369 7.0
21000 -21.0 -5.8 270 33 17 7.7 4.2 19.2 66.6 -2.2 1274 6.5
20000 -18.7 -1.7 270 31 16 7.7 4.2 18.4 65.2 -2.9 1175 6.0
19500 -17.6 0.3 270 31 16 7.7 4.2 18.1 64.6 -3.2 1126 5.7
19000 -16.4 2.5 270 30 15 7.7 4.2 17.8 64.0 -3.5 1076 5.5
18500 -15.3 4.5 270 29 15 7.6 4.2 17.4 63.4 -3.8 1027 5.2
18000 -14.1 6.6 270 28 14 7.6 4.2 17.1 62.7 -4.2 978 5.0
17500 -13.0 8.6 270 27 14 7.6 4.2 16.7 62.1 -4.5 929 4.7
17000 -11.8 10.8 270 26 13 7.7 4.2 16.4 61.5 -4.8 880 4.5
16500 -10.7 12.7 270 25 13 7.6 4.2 16.0 60.9 -5.2 831 4.2
16000 -9.6 14.7 270 24 12 7.4 4.1 15.7 60.2 -5.6 783 4.0
15500 -8.5 16.7 270 23 12 7.4 4.1 15.3 59.5 -6.0 735 3.7
15000 -7.3 18.9 270 21 11 8.0 4.4 14.9 58.9 -6.3 686 3.5
14500 -6.2 20.8 270 21 11 8.0 4.4 14.7 58.4 -6.6 636 3.2
14000 -5.0 23.0 275 20 10 8.1 4.5 14.4 57.9 -6.9 585 3.0
13500 -3.8 25.2 275 20 10 8.2 4.5 14.1 57.4 -7.2 534 2.7
13000 -2.5 27.5 280 19 10 8.5 4.6 13.9 57.0 -7.5 483 2.5
12500 -1.4 29.5 280 20 10 7.5 4.1 13.6 56.5 -7.8 433 2.2
12000 -0.3 31.5 280 20 10 7.0 3.8 13.3 55.9 -8.2 385 2.0
11750 0.2 32.4 280 20 10 6.2 3.4 13.0 55.4 -8.5 364 1.8
11500 0.7 33.3 280 19 10 6.4 3.5 12.8 55.0 -8.8 343 1.7
11250 1.1 34.0 280 18 9 6.5 3.6 12.5 54.5 -9.1 322 1.6
11000 1.6 34.9 285 17 9 6.1 3.4 12.2 54.0 -9.5 301 1.5
10750 2.0 35.6 285 17 9 5.7 3.1 11.9 53.5 -9.8 282 1.4
10500 2.4 36.3 285 16 8 5.7 3.1 11.6 52.9 -10.2 262 1.3
10250 2.8 37.0 290 16 8 7.3 4.0 11.3 52.4 -10.5 242 1.2
10000 3.3 37.9 290 18 9 8.2 4.5 11.2 52.2 -10.7 218 1.1
9750 3.9 39.0 290 19 10 7.6 4.1 11.1 51.9 -10.9 194 1.0
9500 4.5 40.1 290 19 10 8.0 4.4 10.9 51.6 -11.1 170 0.9
9250 5.0 41.0 290 20 10 7.1 3.9 10.8 51.4 -11.3 145 0.7
9000 5.5 41.9 285 19 10 6.3 3.4 10.5 50.9 -11.6 124 0.6
8750 6.0 42.8 285 19 10 6.0 3.3 10.2 50.4 -11.9 103 0.5
8500 6.4 43.5 280 19 10 7.4 4.0 10.0 50.0 -12.2 81 0.4
8250 6.9 44.4 280 19 10 2.3 1.2 9.7 49.5 -12.5 60 0.3
8000 6.3 43.3 280 18 9 -19.4 -10.6 8.4 47.2 -13.8 69 0.3
7750 4.0 39.2 275 13 7 -39.4 -21.6 5.4 41.7 -16.9 131 0.7
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 * * * * * *
04/17/2024 at 0900 MDT | 04/17/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.1 | CAPE... +24.6 LI... 0.0
CINH... 0.0 K Index... +12.4 | CINH... -0.8 K Index... +15.8
|
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 -57.8 -72.0 270 57 29 3.2 1.7 | -58.3 -72.9 255 57 29 2.7 1.5
45000 -53.4 -64.1 275 64 33 -2.8 -1.5 | -54.5 -66.1 270 68 35 -2.2 -1.2
40000 -56.9 -70.4 270 58 30 -2.1 -1.2 | -57.4 -71.3 275 66 34 -1.7 -1.0
38000 -55.7 -68.3 270 55 28 3.9 2.1 | -55.9 -68.6 280 64 33 4.6 2.5
36000 -53.4 -64.1 270 52 27 3.9 2.1 | -53.1 -63.6 285 60 31 4.6 2.5
34000 -50.3 -58.5 270 50 26 7.5 4.1 | -49.7 -57.5 285 57 29 7.7 4.2
32000 -45.8 -50.4 270 50 26 7.6 4.1 | -45.1 -49.2 280 53 28 7.7 4.2
30000 -41.2 -42.2 275 49 25 7.7 4.2 | -40.5 -40.9 275 51 26 7.4 4.0
29000 -38.9 -38.0 275 49 25 7.7 4.2 | -38.3 -36.9 275 51 26 7.4 4.0
28000 -36.6 -33.9 275 48 25 7.7 4.2 | -36.1 -33.0 270 50 26 7.4 4.0
27000 -34.3 -29.7 275 47 24 7.3 4.0 | -33.9 -29.0 270 50 26 7.6 4.2
26000 -32.2 -26.0 275 46 24 7.2 4.0 | -31.6 -24.9 270 48 25 7.6 4.2
25000 -30.0 -22.0 270 45 23 7.2 4.0 | -28.7 -19.7 275 46 24 7.7 4.2
24000 -27.4 -17.3 270 43 22 6.8 3.7 | -26.5 -15.7 275 45 23 7.1 3.9
23000 -25.3 -13.5 270 42 22 6.9 3.8 | -24.3 -11.7 275 44 23 7.2 3.9
22000 -23.3 -9.9 270 41 21 6.9 3.8 | -22.2 -8.0 270 43 22 7.2 3.9
21000 -21.2 -6.2 270 39 20 7.9 4.3 | -20.1 -4.2 270 41 21 6.8 3.7
20000 -18.8 -1.8 265 36 19 7.9 4.3 | -18.1 -0.6 265 37 19 6.8 3.8
19500 -17.7 0.1 265 35 18 7.9 4.3 | -17.1 1.2 260 35 18 6.9 3.8
19000 -16.5 2.3 265 34 17 8.1 4.4 | -16.1 3.0 260 33 17 6.8 3.8
18500 -15.4 4.3 265 32 16 6.3 3.5 | -15.0 5.0 255 30 16 7.1 3.9
18000 -14.5 5.9 260 29 15 6.5 3.6 | -14.0 6.8 250 27 14 7.0 3.9
17500 -13.5 7.7 260 26 14 7.8 4.3 | -12.9 8.8 245 24 12 7.0 3.9
17000 -12.1 10.2 265 24 13 8.8 4.8 | -11.8 10.8 255 25 13 7.0 3.9
16500 -10.7 12.7 270 23 12 8.8 4.9 | -10.8 12.6 265 27 14 7.0 3.9
16000 -9.5 14.9 275 23 12 8.1 4.4 | -9.8 14.4 270 29 15 6.8 3.7
15500 -8.3 17.1 280 23 12 8.2 4.5 | -8.8 16.2 270 31 16 6.9 3.8
15000 -7.1 19.2 285 23 12 6.9 3.8 | -7.8 18.0 270 30 15 6.5 3.6
14500 -6.1 21.0 290 23 12 6.9 3.8 | -6.9 19.6 270 25 13 6.6 3.6
14000 -5.1 22.8 290 22 12 6.7 3.7 | -6.0 21.2 270 20 10 8.6 4.7
13500 -4.1 24.6 295 21 11 6.7 3.7 | -4.6 23.7 265 16 8 9.5 5.2
13000 -3.2 26.2 295 20 10 7.5 4.1 | -3.2 26.2 265 12 6 11.3 6.2
12500 -2.2 28.0 290 18 9 5.2 2.9 | -1.6 29.1 260 12 6 8.2 4.5
12000 -1.5 29.3 285 16 8 6.4 3.5 | -0.3 31.5 260 11 6 9.2 5.1
11750 -0.9 30.4 285 15 8 7.8 4.3 | 0.4 32.7 260 11 6 10.0 5.5
11500 -0.3 31.5 290 14 7 7.9 4.3 | 1.2 34.2 260 11 5 10.1 5.5
11250 0.2 32.4 290 15 8 8.3 4.6 | 2.0 35.6 260 10 5 10.5 5.8
11000 0.8 33.4 290 17 9 7.8 4.3 | 2.7 36.9 260 10 5 9.7 5.3
10750 1.4 34.5 290 18 9 7.4 4.1 | 3.4 38.1 260 10 5 8.7 4.8
10500 1.9 35.4 290 19 10 7.4 4.0 | 4.1 39.4 260 10 5 9.0 4.9
10250 2.5 36.5 295 20 10 8.6 4.7 | 4.8 40.6 260 9 5 10.4 5.7
10000 3.1 37.6 295 22 11 8.7 4.8 | 5.6 42.1 260 9 5 10.7 5.9
9750 3.7 38.7 290 23 12 7.9 4.4 | 6.4 43.5 260 9 5 10.1 5.5
9500 4.3 39.7 290 23 12 7.6 4.2 | 7.1 44.8 255 9 5 9.9 5.4
9250 4.9 40.8 290 24 12 9.5 5.2 | 7.9 46.2 255 9 4 10.9 6.0
9000 5.7 42.3 290 23 12 8.7 4.8 | 8.7 47.7 255 8 4 10.7 5.9
8750 6.2 43.2 290 21 11 6.0 3.3 | 9.5 49.1 255 8 4 9.7 5.3
8500 6.6 43.9 285 20 10 7.1 3.9 | 10.2 50.4 255 8 4 9.5 5.2
8250 7.1 44.8 285 18 9 5.5 3.0 | 10.9 51.6 255 8 4 11.5 6.3
8000 7.5 45.5 280 16 8 6.5 3.5 | 12.1 53.8 255 7 4 19.2 10.5
7750 8.2 46.8 275 11 6 12.1 6.6 | 13.7 56.7 255 7 3 25.5 14.0
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
04/17/2024 at 1500 MDT | 04/17/2024 at 1800 MDT
|
CAPE... +118.9 LI... -1.6 | CAPE... +45.5 LI... -0.8
CINH... -0.2 K Index... +23.3 | CINH... -1.0 K Index... +21.1
|
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 -59.1 -74.4 265 61 32 3.0 1.7 | -59.6 -75.3 265 57 29 2.6 1.4
45000 -55.0 -67.0 270 72 37 -2.0 -1.1 | -56.2 -69.2 275 75 39 -1.0 -0.6
40000 -57.3 -71.1 275 72 37 -1.3 -0.7 | -57.9 -72.2 270 70 36 -1.0 -0.6
38000 -55.5 -67.9 280 71 36 4.6 2.5 | -55.8 -68.4 270 69 36 5.3 2.9
36000 -52.8 -63.0 280 70 36 4.6 2.5 | -52.7 -62.9 275 68 35 5.3 2.9
34000 -49.3 -56.7 285 66 34 8.0 4.4 | -49.0 -56.2 275 67 34 8.0 4.4
32000 -44.5 -48.1 275 57 29 8.0 4.4 | -43.5 -46.3 275 63 32 8.1 4.4
30000 -39.7 -39.5 270 51 26 7.8 4.3 | -38.8 -37.8 275 59 31 7.6 4.2
29000 -37.4 -35.3 270 51 26 7.8 4.3 | -36.6 -33.9 275 58 30 7.6 4.2
28000 -35.0 -31.0 270 51 26 7.8 4.3 | -34.3 -29.7 275 56 29 7.6 4.2
27000 -32.7 -26.9 270 50 26 6.8 3.8 | -32.1 -25.8 275 54 28 6.7 3.7
26000 -30.7 -23.3 270 50 26 6.7 3.7 | -30.1 -22.2 275 52 27 6.8 3.7
25000 -28.2 -18.8 275 50 26 6.7 3.7 | -28.0 -18.4 275 50 26 6.8 3.7
24000 -26.2 -15.2 275 50 26 7.4 4.1 | -26.0 -14.8 275 47 24 7.0 3.8
23000 -24.0 -11.2 275 47 24 7.4 4.1 | -23.9 -11.0 275 42 22 7.1 3.9
22000 -21.8 -7.2 275 45 23 7.4 4.1 | -21.8 -7.2 270 38 20 7.1 3.9
21000 -19.7 -3.5 275 42 22 5.7 3.1 | -19.7 -3.5 275 34 18 6.2 3.4
20000 -18.0 -0.4 270 39 20 5.8 3.2 | -17.4 0.7 275 33 17 6.3 3.4
19500 -17.2 1.0 270 38 19 5.9 3.2 | -16.5 2.3 275 32 16 6.3 3.5
19000 -16.3 2.7 265 36 19 5.8 3.2 | -15.6 3.9 275 31 16 6.3 3.5
18500 -15.4 4.3 265 34 17 7.5 4.1 | -14.7 5.5 275 29 15 5.7 3.1
18000 -14.3 6.3 265 31 16 7.4 4.0 | -13.9 7.0 270 26 13 5.8 3.2
17500 -13.3 8.1 260 29 15 8.3 4.6 | -13.1 8.4 270 24 12 8.1 4.4
17000 -11.9 10.6 260 26 13 9.0 5.0 | -11.8 10.8 265 23 12 8.9 4.9
16500 -10.6 12.9 260 23 12 9.2 5.0 | -10.5 13.1 265 22 11 9.2 5.0
16000 -9.2 15.4 255 22 11 9.7 5.3 | -9.1 15.6 265 22 11 9.7 5.3
15500 -7.8 18.0 255 20 10 9.6 5.3 | -7.6 18.3 265 21 11 9.6 5.3
15000 -6.3 20.7 255 19 10 9.9 5.4 | -6.2 20.8 265 21 11 9.9 5.5
14500 -4.9 23.2 255 19 10 9.9 5.4 | -4.7 23.5 265 21 11 9.9 5.4
14000 -3.4 25.9 255 18 9 9.7 5.3 | -3.2 26.2 265 20 10 10.1 5.5
13500 -1.9 28.6 250 18 9 9.8 5.4 | -1.7 28.9 265 20 10 10.1 5.6
13000 -0.5 31.1 250 17 9 12.1 6.7 | -0.2 31.6 265 20 10 11.6 6.4
12500 1.2 34.2 250 17 9 8.1 4.4 | 1.3 34.3 265 20 10 8.0 4.4
12000 2.5 36.5 250 16 8 9.1 5.0 | 2.6 36.7 265 20 10 9.3 5.1
11750 3.2 37.8 245 16 8 9.9 5.4 | 3.3 37.9 270 20 10 10.7 5.8
11500 4.0 39.2 245 16 8 9.8 5.4 | 4.1 39.4 270 20 10 10.0 5.5
11250 4.7 40.5 245 16 8 9.9 5.4 | 4.8 40.6 270 20 10 10.0 5.5
11000 5.4 41.7 245 15 8 9.7 5.3 | 5.6 42.1 270 20 10 9.6 5.3
10750 6.1 43.0 245 15 8 9.2 5.1 | 6.3 43.3 270 20 10 8.9 4.9
10500 6.8 44.2 245 15 8 9.5 5.2 | 6.9 44.4 270 19 10 9.3 5.1
10250 7.6 45.7 245 15 8 10.8 5.9 | 7.7 45.9 270 19 10 10.5 5.8
10000 8.4 47.1 245 15 8 10.6 5.8 | 8.5 47.3 270 19 10 10.2 5.6
9750 9.1 48.4 245 14 7 9.7 5.3 | 9.2 48.6 270 19 10 9.5 5.2
9500 9.9 49.8 245 14 7 9.5 5.2 | 9.9 49.8 270 19 10 9.1 5.0
9250 10.6 51.1 245 14 7 10.4 5.7 | 10.6 51.1 270 19 10 10.9 6.0
9000 11.4 52.5 245 14 7 10.9 6.0 | 11.5 52.7 270 18 10 11.2 6.2
8750 12.2 54.0 240 14 7 10.3 5.7 | 12.2 54.0 270 18 9 9.5 5.2
8500 13.0 55.4 240 13 7 10.8 5.9 | 13.0 55.4 270 18 9 10.0 5.5
8250 13.8 56.8 240 13 7 9.4 5.2 | 13.7 56.7 270 17 9 9.4 5.2
8000 14.6 58.3 240 12 6 16.3 8.9 | 14.4 57.9 270 17 9 11.4 6.3
7750 16.4 61.5 240 11 6 31.2 17.1 | 15.4 59.7 270 14 7 16.2 8.9
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
- National Weather Service
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- 8250 Kentucky Highway 3520
- West Paducah, KY 42086-9762
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- Page last modified: Sep 19th, 2023 19:10 UTC