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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 231223
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0623 MDT Tuesday, April 23, 2024
This forecast is for the Air Force Academy for Tuesday, April 23, 2024:
If the trigger temperature of 57.7 F/14.3 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 385 ft/min (2.0 m/s)
Maximum height of thermals.................. 13914 ft MSL (6295 ft AGL)
Forecast maximum temperature................... 60.0 F/16.0 C
Time of trigger temperature.................... 1300 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 10097 ft MSL (2478 ft AGL)
Thermal soaring outlook for Wednesday 04/24.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:10:18 / 19:44:37 MDT
Total possible sunshine........... 13 hr 34 min 20 sec (814 min 20 sec)
Altitude of sun at 12:57:27 MDT... 63.90 degrees
Upper air data from numerical model forecast valid on 04/23/2024 at 0600 MDT
Freezing level.................. 12632 ft MSL (5013 ft AGL)
Convective condensation level... 15989 ft MSL (8370 ft AGL)
Lifted condensation level....... 15657 ft MSL (8038 ft AGL)
Lifted index.................... +2.8
K index......................... +18.2
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 -60.2 -76.4 285 63 33 -0.6 -0.3 M M M M M
45000 -61.0 -77.8 285 65 33 1.0 0.5 M M M M M
40000 -59.8 -75.6 280 71 36 0.9 0.5 M M M M M
38000 -56.2 -69.2 280 66 34 6.9 3.8 M M M M M
36000 -52.1 -61.8 275 59 30 6.9 3.8 M M M M M
34000 -47.7 -53.9 275 54 28 7.9 4.4 M M M M M
32000 -42.9 -45.2 280 52 27 7.9 4.4 M M M M M
30000 -38.0 -36.4 280 50 25 8.5 4.7 31.0 87.8 11.9 M M
29000 -35.5 -31.9 280 48 25 8.5 4.7 30.5 86.8 11.7 M M
28000 -32.9 -27.2 280 47 24 8.5 4.7 30.0 86.1 11.5 M M
27000 -30.6 -23.1 280 46 24 5.1 2.8 29.3 84.8 11.0 M M
26000 -29.0 -20.2 280 44 23 5.5 3.0 27.6 81.7 9.8 M M
25000 -27.4 -17.3 275 43 22 5.5 3.0 26.1 79.0 8.6 M M
24000 -25.8 -14.4 275 41 21 5.1 2.8 24.7 76.4 7.5 M M
23000 -24.3 -11.7 275 40 20 5.0 2.7 22.8 73.1 6.0 M M
22000 -22.5 -8.5 275 38 20 5.1 2.8 20.7 69.3 4.3 M M
21000 -20.6 -5.1 275 36 19 8.4 4.6 19.6 67.4 3.3 M M
20000 -18.1 -0.6 275 34 18 8.4 4.6 19.2 66.5 2.9 M M
19500 -16.9 1.6 280 33 17 8.4 4.6 18.9 66.1 2.7 M M
19000 -15.6 3.9 280 32 17 8.4 4.6 18.8 65.8 2.5 M M
18500 -14.4 6.1 280 31 16 7.9 4.3 18.5 65.3 2.3 M M
18000 -13.3 8.1 280 30 16 7.9 4.3 18.2 64.7 2.0 M M
17500 -12.1 10.2 280 30 15 8.0 4.4 17.9 64.2 1.7 M M
17000 -10.9 12.4 285 29 15 8.0 4.4 17.6 63.6 1.5 M M
16500 -9.7 14.5 285 28 14 8.1 4.4 17.3 63.1 1.2 M M
16000 -8.5 16.7 285 27 14 8.2 4.5 17.0 62.7 0.9 M M
15500 -7.3 18.9 285 26 13 8.2 4.5 16.8 62.2 0.7 M M
15000 -6.1 21.0 290 25 13 8.4 4.6 16.6 61.8 0.5 M M
14500 -4.8 23.4 290 23 12 8.4 4.6 16.3 61.4 0.3 M M
14000 -3.6 25.5 295 22 12 8.3 4.6 16.1 61.0 0.0 M M
13500 -2.3 27.9 295 22 11 8.3 4.6 15.9 60.6 -0.2 544 2.8
13000 -1.1 30.0 295 21 11 9.7 5.3 15.7 60.3 -0.4 492 2.5
12500 0.2 32.4 295 21 11 7.0 3.8 15.5 59.9 -0.5 438 2.2
12000 1.3 34.3 300 21 11 7.4 4.1 15.1 59.3 -0.9 390 2.0
11750 1.9 35.4 300 20 10 7.6 4.2 15.0 58.9 -1.1 366 1.9
11500 2.4 36.3 305 20 10 7.6 4.2 14.8 58.6 -1.3 342 1.7
11250 3.0 37.4 305 19 10 8.1 4.5 14.6 58.4 -1.4 318 1.6
11000 3.6 38.5 305 18 9 6.8 3.7 14.5 58.1 -1.6 293 1.5
10750 4.0 39.2 310 18 9 5.6 3.1 14.2 57.5 -1.9 273 1.4
10500 4.4 39.9 315 18 9 5.8 3.2 13.9 57.0 -2.2 253 1.3
10250 4.8 40.6 315 18 9 5.0 2.7 13.6 56.4 -2.5 234 1.2
10000 5.1 41.2 320 17 9 1.9 1.1 13.1 55.6 -3.0 219 1.1
9750 5.1 41.2 325 18 9 0.4 0.2 12.4 54.3 -3.8 211 1.1
9500 5.1 41.2 325 19 10 0.1 0.0 11.7 53.0 -4.5 202 1.0
9250 5.1 41.2 330 19 10 3.0 1.6 11.0 51.8 -5.2 194 1.0
9000 5.4 41.7 335 20 10 0.3 0.2 10.5 50.9 -5.7 179 0.9
8750 5.1 41.2 340 22 11 -4.7 -2.6 9.5 49.1 -6.7 180 0.9
8500 4.8 40.6 340 24 12 -3.3 -1.8 8.5 47.3 -7.7 181 0.9
8250 4.5 40.1 345 26 13 -3.8 -2.1 7.5 45.5 -8.8 182 0.9
8000 4.4 39.9 340 25 13 0.8 0.4 6.6 43.8 -9.7 180 0.9
7750 4.7 40.5 340 20 10 8.6 4.7 6.2 43.2 -10.1 162 0.8
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 * * * * * *
04/23/2024 at 0900 MDT | 04/23/2024 at 1200 MDT
|
CAPE... 0.0 LI... -0.6 | CAPE... +14.2 LI... -1.5
CINH... 0.0 K Index... +17.3 | CINH... -3.9 K Index... +21.8
|
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 -59.4 -74.9 290 63 33 -0.8 -0.5 | -58.5 -73.3 290 62 32 -0.1 -0.0
45000 -60.5 -76.9 285 65 34 0.5 0.2 | -58.7 -73.7 285 64 33 -1.0 -0.5
40000 -60.1 -76.2 275 68 35 0.4 0.2 | -60.2 -76.4 280 66 34 -0.7 -0.4
38000 -56.7 -70.1 275 64 33 6.8 3.7 | -57.5 -71.5 275 64 33 6.4 3.5
36000 -52.7 -62.9 275 59 31 6.8 3.7 | -53.7 -64.7 275 60 31 6.4 3.5
34000 -48.3 -54.9 275 55 28 7.8 4.3 | -49.5 -57.1 275 57 30 8.3 4.6
32000 -43.7 -46.7 280 51 26 7.8 4.3 | -43.9 -47.0 280 55 28 8.3 4.6
30000 -38.8 -37.8 285 49 25 8.8 4.8 | -38.8 -37.8 280 52 27 8.6 4.7
29000 -36.1 -33.0 285 49 25 8.8 4.8 | -36.2 -33.2 280 50 26 8.6 4.7
28000 -33.5 -28.3 285 49 25 8.8 4.8 | -33.6 -28.5 280 48 25 8.6 4.7
27000 -31.1 -24.0 285 48 25 5.4 3.0 | -31.3 -24.3 280 47 24 6.3 3.5
26000 -29.4 -20.9 280 45 23 5.8 3.2 | -29.4 -20.9 285 47 24 6.4 3.5
25000 -27.7 -17.9 280 42 22 5.8 3.2 | -27.5 -17.5 285 47 24 6.4 3.5
24000 -26.0 -14.8 275 39 20 5.1 2.8 | -25.7 -14.3 285 45 23 5.2 2.8
23000 -24.5 -12.1 280 37 19 5.0 2.7 | -24.2 -11.6 280 41 21 5.3 2.9
22000 -22.6 -8.7 280 35 18 5.2 2.8 | -22.6 -8.7 280 37 19 5.3 2.9
21000 -20.7 -5.3 285 34 17 8.0 4.4 | -20.8 -5.4 280 34 18 8.2 4.5
20000 -18.3 -0.9 285 33 17 8.2 4.5 | -18.5 -1.3 280 32 17 8.0 4.4
19500 -17.1 1.2 285 32 17 8.2 4.5 | -16.7 1.9 280 31 16 8.0 4.4
19000 -15.9 3.4 290 32 16 8.3 4.6 | -15.5 4.1 285 30 15 8.2 4.5
18500 -14.6 5.7 290 32 16 8.7 4.8 | -14.3 6.3 285 29 15 8.5 4.7
18000 -13.3 8.1 290 32 16 8.8 4.8 | -13.0 8.6 285 29 15 8.5 4.7
17500 -12.0 10.4 290 32 16 7.8 4.3 | -11.8 10.8 285 28 14 8.3 4.6
17000 -10.9 12.4 290 31 16 7.7 4.2 | -10.6 12.9 285 28 14 8.3 4.6
16500 -9.8 14.4 290 30 16 7.8 4.3 | -9.3 15.3 285 27 14 8.2 4.5
16000 -8.6 16.5 290 28 14 7.8 4.3 | -8.1 17.4 285 26 14 8.1 4.5
15500 -7.5 18.5 290 26 13 7.9 4.3 | -7.0 19.4 280 25 13 8.1 4.5
15000 -6.2 20.8 290 23 12 9.0 4.9 | -5.8 21.6 280 25 13 8.1 4.5
14500 -4.9 23.2 285 21 11 8.9 4.9 | -4.6 23.7 280 24 12 8.1 4.4
14000 -3.6 25.5 285 20 10 8.8 4.8 | -3.3 26.1 275 23 12 9.1 5.0
13500 -2.4 27.7 285 20 10 8.8 4.8 | -2.0 28.4 270 20 11 9.0 4.9
13000 -1.0 30.2 285 21 11 9.3 5.1 | -0.7 30.7 270 18 9 9.1 5.0
12500 0.3 32.5 285 22 11 8.4 4.6 | 0.6 33.1 260 17 9 8.8 4.9
12000 1.5 34.7 285 21 11 7.9 4.4 | 1.8 35.2 255 15 8 6.9 3.8
11750 2.1 35.8 285 20 11 7.4 4.1 | 2.3 36.1 250 14 7 6.2 3.4
11500 2.6 36.7 285 20 10 8.6 4.7 | 2.7 36.9 245 14 7 6.9 3.8
11250 3.3 37.9 280 19 10 9.4 5.2 | 3.3 37.9 235 14 7 6.5 3.6
11000 3.9 39.0 280 17 9 6.2 3.4 | 3.6 38.5 235 13 7 4.0 2.2
10750 4.3 39.7 285 16 8 4.5 2.5 | 3.9 39.0 235 13 7 2.8 1.5
10500 4.7 40.5 285 15 8 4.8 2.7 | 4.1 39.4 235 12 6 3.6 2.0
10250 5.1 41.2 290 13 7 7.2 3.9 | 4.4 39.9 235 12 6 4.1 2.3
10000 5.5 41.9 295 12 6 1.6 0.9 | 4.6 40.3 235 11 5 0.5 0.3
9750 5.3 41.5 305 12 6 -4.7 -2.6 | 4.5 40.1 235 9 5 -2.0 -1.1
9500 5.0 41.0 315 13 6 -2.3 -1.3 | 4.4 39.9 235 7 4 -1.6 -0.9
9250 4.8 40.6 320 13 7 -5.4 -2.9 | 4.3 39.7 240 5 3 -0.4 -0.2
9000 4.2 39.6 325 15 8 -10.2 -5.6 | 4.5 40.1 240 3 2 6.2 3.4
8750 3.3 37.9 330 17 9 -10.3 -5.7 | 5.1 41.2 240 1 1 9.8 5.4
8500 2.5 36.5 335 19 10 -12.9 -7.1 | 5.8 42.4 070 1 0 8.7 4.8
8250 1.7 35.1 335 20 11 -2.6 -1.4 | 6.4 43.5 065 3 1 9.5 5.2
8000 2.4 36.3 335 19 10 16.7 9.1 | 7.4 45.3 070 3 1 17.4 9.6
7750 3.7 38.7 340 17 9 17.2 9.4 | 9.1 48.4 075 3 2 28.9 15.8
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
04/23/2024 at 1500 MDT | 04/23/2024 at 1800 MDT
|
CAPE... +13.6 LI... -1.3 | CAPE... +12.6 LI... -1.4
CINH... -10.2 K Index... +26.1 | CINH... -15.9 K Index... +24.0
|
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 -59.3 -74.7 290 65 33 -0.3 -0.2 | -58.6 -73.5 290 65 33 0.0 0.0
45000 -59.8 -75.6 285 70 36 -0.2 -0.1 | -58.7 -73.7 285 73 38 -0.7 -0.4
40000 -60.1 -76.2 280 70 36 -0.1 -0.1 | -59.7 -75.5 285 82 42 -0.4 -0.2
38000 -57.2 -71.0 280 67 35 6.4 3.5 | -56.8 -70.2 280 78 40 6.6 3.6
36000 -53.3 -63.9 275 64 33 6.4 3.5 | -52.3 -62.1 280 71 37 6.7 3.6
34000 -49.2 -56.6 275 61 31 7.8 4.3 | -48.2 -54.8 280 65 34 7.0 3.9
32000 -43.9 -47.0 275 58 30 7.8 4.3 | -44.0 -47.2 280 60 31 7.1 3.9
30000 -39.0 -38.2 275 55 29 8.7 4.8 | -39.3 -38.7 280 54 28 8.7 4.8
29000 -36.3 -33.3 275 54 28 8.7 4.8 | -36.7 -34.1 285 51 26 8.7 4.8
28000 -33.7 -28.7 275 53 27 8.6 4.7 | -34.1 -29.4 285 47 24 8.6 4.7
27000 -31.5 -24.7 275 51 26 5.8 3.2 | -31.7 -25.1 285 45 23 6.9 3.8
26000 -29.8 -21.6 275 48 25 5.9 3.2 | -29.6 -21.3 285 44 23 7.0 3.8
25000 -28.0 -18.4 280 45 23 5.9 3.2 | -27.6 -17.7 285 43 22 7.0 3.8
24000 -26.2 -15.2 280 42 22 8.0 4.4 | -25.5 -13.9 280 43 22 6.5 3.6
23000 -23.9 -11.0 280 39 20 7.8 4.3 | -23.5 -10.3 280 44 23 6.6 3.6
22000 -21.6 -6.9 285 36 18 7.8 4.3 | -21.6 -6.9 275 45 23 6.6 3.6
21000 -19.3 -2.7 285 33 17 7.7 4.2 | -18.9 -2.0 270 45 23 7.8 4.3
20000 -17.1 1.2 280 31 16 7.7 4.2 | -16.6 2.1 265 43 22 7.9 4.3
19500 -15.9 3.4 280 30 15 7.7 4.2 | -15.5 4.1 265 41 21 8.0 4.4
19000 -14.3 6.3 275 28 15 7.8 4.3 | -14.3 6.3 260 40 21 8.5 4.7
18500 -13.1 8.4 275 28 14 7.8 4.3 | -13.0 8.6 260 37 19 9.2 5.0
18000 -12.0 10.4 270 28 14 7.8 4.3 | -11.7 10.9 255 34 18 9.3 5.1
17500 -10.8 12.6 270 27 14 7.8 4.3 | -10.4 13.3 255 33 17 9.1 5.0
17000 -9.7 14.5 265 26 13 7.8 4.3 | -9.1 15.6 250 32 16 9.2 5.0
16500 -8.5 16.7 265 25 13 8.2 4.5 | -7.7 18.1 250 31 16 9.3 5.1
16000 -7.3 18.9 260 24 12 8.5 4.7 | -6.3 20.7 250 31 16 9.4 5.2
15500 -6.1 21.0 260 23 12 8.6 4.7 | -4.9 23.2 245 31 16 9.4 5.1
15000 -4.8 23.4 260 22 11 9.0 4.9 | -3.5 25.7 245 30 15 9.2 5.0
14500 -3.4 25.9 255 21 11 9.0 4.9 | -2.2 28.0 240 29 15 9.3 5.1
14000 -2.1 28.2 255 21 11 9.3 5.1 | -0.9 30.4 240 28 15 7.8 4.3
13500 -0.7 30.7 255 19 10 9.2 5.0 | 0.2 32.4 235 27 14 8.2 4.5
13000 0.7 33.3 250 18 9 10.1 5.5 | 1.2 34.2 230 26 14 5.2 2.8
12500 2.1 35.8 245 17 9 8.5 4.7 | 1.8 35.2 225 26 13 3.0 1.7
12000 3.2 37.8 240 17 9 5.7 3.1 | 1.9 35.4 220 25 13 -1.5 -0.8
11750 3.6 38.5 235 17 9 5.2 2.9 | 1.7 35.1 215 23 12 -3.6 -2.0
11500 4.0 39.2 235 18 9 4.5 2.5 | 1.5 34.7 210 22 11 -1.3 -0.7
11250 4.2 39.6 230 18 9 1.4 0.8 | 1.5 34.7 205 20 10 1.1 0.6
11000 4.1 39.4 225 18 9 -4.3 -2.4 | 1.6 34.9 200 18 9 2.5 1.4
10750 3.6 38.5 220 17 9 -7.0 -3.8 | 1.8 35.2 190 17 9 3.6 2.0
10500 3.1 37.6 210 16 8 -7.0 -3.8 | 2.1 35.8 185 16 8 3.4 1.9
10250 2.6 36.7 205 16 8 -3.0 -1.7 | 2.4 36.3 175 15 8 8.1 4.5
10000 2.7 36.9 195 15 8 6.3 3.5 | 3.2 37.8 170 15 8 10.9 6.0
9750 3.3 37.9 190 15 8 9.1 5.0 | 4.0 39.2 170 15 8 9.5 5.2
9500 4.0 39.2 180 15 8 8.6 4.7 | 4.7 40.5 170 15 8 10.3 5.7
9250 4.6 40.3 175 15 7 7.9 4.3 | 5.4 41.7 170 15 8 8.4 4.6
9000 5.2 41.4 175 15 8 9.1 5.0 | 6.0 42.8 170 15 8 9.0 4.9
8750 6.0 42.8 170 15 8 10.9 6.0 | 6.8 44.2 165 15 8 11.2 6.1
8500 6.8 44.2 170 15 7 10.6 5.8 | 7.6 45.7 165 15 7 10.8 5.9
8250 7.5 45.5 170 15 7 10.0 5.5 | 8.4 47.1 165 14 7 10.2 5.6
8000 8.4 47.1 170 14 7 15.1 8.3 | 9.2 48.6 165 14 7 12.8 7.0
7750 9.9 49.8 165 13 7 25.8 14.2 | 10.4 50.7 160 12 6 19.3 10.6
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
- La Crosse, WI Weather Forecast Office
- N2788 County Road FA
- LaCrosse, WI 54601
- 608-784-7294
- Page Author: ARX Webmaster
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- Page last modified: Sep 19th, 2023 19:10 UTC