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Soaring Guidance
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
000
UXUS97 KPUB 181229
SRGPUB
Soaring Forecast
National Weather Service Pueblo, Colorado
0628 MDT Thursday, April 18, 2024
This forecast is for the Air Force Academy for Thursday, April 18, 2024:
If the trigger temperature of 53.9 F/12.2 C is reached...then
Thermal Soaring Index....................... Poor
Maximum rate of lift........................ 0 ft/min (0.0 m/s)
Maximum height of thermals.................. 10684 ft MSL (3065 ft AGL)
Forecast maximum temperature................... 50.0 F/10.5 C
Time of trigger temperature.................... None
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast opaque middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 10020 ft MSL (2401 ft AGL)
Thermal soaring outlook for Friday 04/19....... Poor
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:17:08 / 19:39:45 MDT
Total possible sunshine........... 13 hr 22 min 37 sec (802 min 37 sec)
Altitude of sun at 12:58:27 MDT... 62.22 degrees
Upper air data from numerical model forecast valid on 04/18/2024 at 0600 MDT
Freezing level.................. 10172 ft MSL (2553 ft AGL)
Additional freezing level....... 11643 ft MSL (4024 ft AGL)
Convective condensation level... 14787 ft MSL (7168 ft AGL)
Lifted condensation level....... 13573 ft MSL (5954 ft AGL)
Lifted index.................... +6.0
K index......................... +15.3
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 -58.0 -72.4 260 56 29 3.8 2.1 M M M M M
45000 -52.8 -63.0 265 67 35 -3.7 -2.0 M M M M M
40000 -57.2 -71.0 265 66 34 -2.7 -1.5 M M M M M
38000 -55.6 -68.1 270 66 34 4.9 2.7 M M M M M
36000 -52.7 -62.9 270 66 34 4.9 2.7 M M M M M
34000 -49.1 -56.4 270 65 34 8.0 4.4 M M M M M
32000 -44.3 -47.7 270 61 31 8.0 4.4 M M M M M
30000 -39.6 -39.3 265 57 29 7.5 4.1 29.8 85.7 15.3 M M
29000 -37.3 -35.1 265 55 29 7.5 4.1 28.9 84.0 14.7 M M
28000 -35.1 -31.2 265 54 28 7.5 4.1 28.1 82.5 14.2 M M
27000 -32.9 -27.2 265 52 27 7.4 4.0 27.3 81.1 13.8 M M
26000 -30.7 -23.3 265 51 26 7.4 4.0 26.3 79.3 13.2 M M
25000 -27.9 -18.2 265 49 25 7.4 4.0 25.2 77.4 12.5 M M
24000 -25.7 -14.3 265 48 25 6.9 3.8 24.4 75.9 11.9 M M
23000 -23.7 -10.7 265 48 25 6.9 3.8 23.3 73.9 11.1 M M
22000 -21.6 -6.9 265 48 24 6.9 3.8 22.3 72.1 10.4 M M
21000 -19.7 -3.5 265 47 24 5.6 3.1 21.2 70.1 9.5 M M
20000 -18.0 -0.4 265 44 23 5.7 3.1 19.7 67.5 8.4 M M
19500 -17.1 1.2 265 43 22 5.7 3.1 19.1 66.3 7.8 M M
19000 -16.3 2.7 265 42 22 5.8 3.2 18.4 65.1 7.3 M M
18500 -15.5 4.1 265 41 21 4.8 2.6 17.7 63.8 6.6 M M
18000 -14.8 5.4 270 40 21 4.9 2.7 16.8 62.3 5.9 M M
17500 -14.1 6.6 270 39 20 5.3 2.9 16.0 60.9 5.2 M M
17000 -13.3 8.1 270 39 20 5.9 3.2 15.4 59.7 4.6 M M
16500 -12.4 9.7 275 39 20 6.0 3.3 14.8 58.6 4.0 M M
16000 -11.4 11.5 275 38 20 8.2 4.5 14.3 57.8 3.6 M M
15500 -10.2 13.6 275 37 19 8.0 4.4 14.1 57.3 3.3 M M
15000 -9.0 15.8 275 36 18 9.2 5.1 13.9 56.9 3.1 M M
14500 -7.6 18.3 275 34 17 9.3 5.1 13.8 56.8 3.0 M M
14000 -6.2 20.8 275 32 16 9.6 5.3 13.7 56.7 2.9 M M
13500 -4.7 23.5 275 30 15 9.7 5.3 13.7 56.7 3.0 M M
13000 -3.3 26.1 270 28 14 9.6 5.2 13.7 56.7 3.0 M M
12500 -1.9 28.6 265 26 14 8.7 4.8 13.6 56.6 2.9 M M
12000 -0.6 30.9 260 25 13 6.8 3.8 13.5 56.3 2.8 M M
11750 -0.2 31.6 260 24 12 3.8 2.1 13.1 55.6 2.4 M M
11500 0.1 32.2 260 23 12 4.5 2.5 12.6 54.8 2.0 M M
11250 0.5 32.9 260 23 12 7.3 4.0 12.3 54.2 1.7 M M
11000 1.0 33.8 255 22 12 2.7 1.5 12.1 53.7 1.5 M M
10750 0.8 33.4 255 21 11 -3.8 -2.1 11.2 52.1 0.6 M M
10500 0.6 33.1 260 19 10 -2.8 -1.5 10.2 50.3 -0.4 301 1.5
10250 0.3 32.5 265 18 9 -4.6 -2.5 9.2 48.5 -1.4 301 1.5
10000 -0.2 31.6 265 17 9 -7.2 -4.0 7.9 46.3 -2.6 309 1.6
9750 -0.8 30.6 270 15 7 -8.3 -4.5 6.6 43.8 -4.0 319 1.6
9500 -1.4 29.5 275 13 6 -6.2 -3.4 5.2 41.4 -5.3 329 1.7
9250 -2.0 28.4 285 11 6 -13.6 -7.5 3.9 39.0 -6.7 340 1.7
9000 -3.1 26.4 300 9 5 -7.8 -4.3 2.0 35.6 -8.6 367 1.9
8750 -3.0 26.6 310 9 4 4.1 2.2 1.3 34.4 -9.2 356 1.8
8500 -2.9 26.8 325 9 4 0.2 0.1 0.7 33.3 -9.9 346 1.8
8250 -2.8 27.0 335 9 5 3.9 2.1 0.1 32.2 -10.5 335 1.7
8000 -2.3 27.9 340 9 5 10.0 5.5 -0.1 31.8 -10.7 312 1.6
7750 -1.4 29.5 350 8 4 12.3 6.7 0.0 32.0 -10.7 279 1.4
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 * * * * * *
04/18/2024 at 0900 MDT | 04/18/2024 at 1200 MDT
|
CAPE... +4.4 LI... +1.2 | CAPE... +10.2 LI... +0.4
CINH... 0.0 K Index... +14.4 | CINH... 0.0 K Index... +16.4
|
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 -58.5 -73.3 260 56 29 4.1 2.3 | -58.3 -72.9 265 54 28 3.0 1.6
45000 -52.9 -63.2 260 69 35 -3.9 -2.2 | -54.3 -65.7 260 72 37 -3.0 -1.7
40000 -57.8 -72.0 265 67 34 -2.9 -1.6 | -58.0 -72.4 265 69 35 -2.1 -1.2
38000 -55.9 -68.6 265 66 34 5.6 3.1 | -55.8 -68.4 265 69 36 5.9 3.3
36000 -52.6 -62.7 265 65 34 5.6 3.1 | -52.2 -62.0 265 71 36 5.9 3.3
34000 -48.8 -55.8 265 64 33 7.4 4.1 | -48.5 -55.3 265 70 36 6.6 3.6
32000 -44.3 -47.7 265 60 31 7.4 4.1 | -44.5 -48.1 265 65 34 6.6 3.6
30000 -39.7 -39.5 265 58 30 8.0 4.4 | -40.2 -40.4 265 62 32 8.5 4.6
29000 -37.3 -35.1 265 57 29 8.0 4.4 | -37.6 -35.7 265 62 32 8.5 4.7
28000 -34.9 -30.8 265 56 29 8.0 4.4 | -35.1 -31.2 265 62 32 8.5 4.7
27000 -32.6 -26.7 265 56 29 7.2 4.0 | -32.6 -26.7 265 61 32 7.5 4.1
26000 -30.5 -22.9 265 54 28 7.1 3.9 | -30.4 -22.7 265 60 31 7.2 4.0
25000 -27.8 -18.0 265 51 26 7.1 3.9 | -27.7 -17.9 270 58 30 7.2 4.0
24000 -25.7 -14.3 265 49 25 6.8 3.7 | -25.6 -14.1 270 56 29 6.5 3.6
23000 -23.7 -10.7 265 49 25 6.8 3.8 | -23.7 -10.7 270 55 28 6.5 3.6
22000 -21.6 -6.9 265 48 25 6.8 3.8 | -21.7 -7.1 270 54 28 6.5 3.6
21000 -19.7 -3.5 265 47 24 5.8 3.2 | -19.9 -3.8 270 53 27 5.8 3.2
20000 -17.9 -0.2 265 47 24 5.9 3.2 | -18.1 -0.6 270 52 27 5.8 3.2
19500 -17.0 1.4 265 47 24 5.9 3.2 | -17.3 0.9 270 52 27 5.8 3.2
19000 -16.2 2.8 270 47 24 6.0 3.3 | -16.4 2.5 270 51 27 5.8 3.2
18500 -15.4 4.3 270 46 24 4.8 2.7 | -15.5 4.1 275 51 26 5.9 3.3
18000 -14.6 5.7 270 45 23 5.0 2.7 | -14.7 5.5 275 50 26 6.0 3.3
17500 -13.9 7.0 270 45 23 5.8 3.2 | -13.8 7.2 275 50 26 6.5 3.5
17000 -12.9 8.8 270 44 23 6.6 3.6 | -12.8 9.0 275 49 25 7.0 3.8
16500 -12.0 10.4 275 43 22 6.7 3.7 | -11.7 10.9 275 47 24 7.0 3.9
16000 -11.0 12.2 275 43 22 6.7 3.7 | -10.7 12.7 270 46 24 7.5 4.1
15500 -10.0 14.0 275 42 22 6.6 3.6 | -9.6 14.7 270 45 23 7.5 4.1
15000 -9.0 15.8 280 42 21 7.4 4.1 | -8.5 16.7 270 43 22 6.8 3.7
14500 -8.0 17.6 275 40 21 7.4 4.1 | -7.6 18.3 270 42 21 6.7 3.7
14000 -6.8 19.8 275 38 20 8.2 4.5 | -6.5 20.3 270 40 20 8.1 4.5
13500 -5.6 21.9 275 35 18 8.5 4.6 | -5.3 22.5 265 38 20 8.7 4.8
13000 -4.4 24.1 275 32 17 9.2 5.0 | -4.0 24.8 265 37 19 9.2 5.0
12500 -2.9 26.8 270 29 15 9.0 4.9 | -2.6 27.3 260 35 18 8.7 4.8
12000 -1.6 29.1 270 27 14 6.2 3.4 | -1.3 29.7 260 33 17 5.1 2.8
11750 -1.3 29.7 270 26 13 2.3 1.3 | -1.2 29.8 255 32 17 0.1 0.1
11500 -1.1 30.0 265 25 13 3.0 1.7 | -1.2 29.8 255 31 16 -0.2 -0.1
11250 -0.8 30.6 260 24 12 6.2 3.4 | -1.3 29.7 250 30 16 -1.5 -0.8
11000 -0.5 31.1 260 23 12 -1.1 -0.6 | -1.5 29.3 250 29 15 -7.7 -4.2
10750 -1.1 30.0 255 22 11 -10.4 -5.7 | -2.4 27.7 245 26 13 -13.6 -7.4
10500 -1.7 28.9 250 20 10 -6.9 -3.8 | -3.4 25.9 240 22 12 -12.2 -6.7
10250 -2.4 27.7 245 18 10 -13.8 -7.6 | -4.3 24.3 230 19 10 -15.1 -8.3
10000 -3.5 25.7 240 18 9 -9.3 -5.1 | -5.3 22.5 220 17 9 -6.4 -3.5
9750 -3.6 25.5 235 15 8 0.4 0.2 | -5.3 22.5 210 14 7 2.8 1.5
9500 -3.8 25.2 230 12 6 -2.2 -1.2 | -5.2 22.6 195 12 6 0.1 0.1
9250 -3.9 25.0 225 9 5 -1.3 -0.7 | -5.1 22.8 175 11 5 1.6 0.9
9000 -3.9 25.0 215 6 3 3.3 1.8 | -4.9 23.2 165 10 5 5.9 3.2
8750 -3.4 25.9 195 4 2 6.8 3.7 | -4.3 24.3 155 10 5 8.5 4.7
8500 -3.0 26.6 150 3 2 5.7 3.1 | -3.7 25.3 145 10 5 7.3 4.0
8250 -2.5 27.5 105 4 2 6.6 3.6 | -3.2 26.2 135 10 5 9.6 5.3
8000 -1.9 28.6 105 5 3 11.3 6.2 | -2.3 27.9 135 10 5 14.5 8.0
7750 -0.8 30.6 100 5 3 17.1 9.4 | -1.1 30.0 130 9 5 16.4 9.0
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
04/18/2024 at 1500 MDT | 04/18/2024 at 1800 MDT
|
CAPE... +4.2 LI... -0.1 | CAPE... +0.6 LI... -0.7
CINH... 0.0 K Index... +16.0 | CINH... 0.0 K Index... +16.5
|
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 -59.5 -75.1 260 56 29 2.3 1.3 | -59.6 -75.3 265 52 27 2.8 1.5
45000 -56.3 -69.3 270 72 37 -1.0 -0.6 | -55.9 -68.6 275 69 36 -1.2 -0.7
40000 -57.4 -71.3 270 69 35 -0.5 -0.3 | -57.9 -72.2 270 80 41 -1.2 -0.7
38000 -55.1 -67.2 270 69 36 5.4 3.0 | -55.8 -68.4 270 81 41 5.5 3.0
36000 -51.8 -61.2 275 70 36 5.4 3.0 | -52.5 -62.5 270 79 41 5.5 3.0
34000 -48.2 -54.8 275 70 36 7.3 4.0 | -48.8 -55.8 270 77 39 7.9 4.4
32000 -43.8 -46.8 275 69 35 7.3 4.0 | -43.4 -46.1 270 73 38 8.0 4.4
30000 -39.4 -38.9 275 68 35 7.6 4.2 | -38.7 -37.7 275 70 36 7.6 4.2
29000 -37.1 -34.8 275 68 35 7.6 4.2 | -36.5 -33.7 275 70 36 7.6 4.2
28000 -34.8 -30.6 275 67 35 7.6 4.2 | -34.2 -29.6 275 69 35 7.6 4.2
27000 -32.6 -26.7 275 67 34 7.2 3.9 | -32.0 -25.6 275 68 35 6.7 3.7
26000 -30.5 -22.9 275 66 34 7.1 3.9 | -30.0 -22.0 275 67 35 6.8 3.7
25000 -28.3 -18.9 275 65 34 7.1 3.9 | -27.9 -18.2 275 67 34 6.9 3.8
24000 -25.7 -14.3 275 64 33 6.4 3.5 | -25.9 -14.6 275 66 34 6.5 3.6
23000 -23.8 -10.8 275 63 32 6.4 3.5 | -24.0 -11.2 270 65 33 6.3 3.5
22000 -21.9 -7.4 270 61 32 6.4 3.5 | -22.2 -8.0 270 64 33 6.3 3.5
21000 -20.0 -4.0 270 60 31 6.5 3.6 | -20.3 -4.5 270 63 32 6.5 3.6
20000 -18.0 -0.4 270 59 30 6.5 3.6 | -18.3 -0.9 270 61 31 6.5 3.6
19500 -17.1 1.2 275 59 30 6.5 3.6 | -16.9 1.6 270 59 30 6.5 3.6
19000 -16.1 3.0 275 58 30 6.4 3.5 | -15.9 3.4 270 58 30 6.5 3.6
18500 -15.1 4.8 270 58 30 7.0 3.8 | -14.9 5.2 270 57 29 6.8 3.7
18000 -14.1 6.6 270 57 29 7.0 3.8 | -13.9 7.0 270 55 28 6.8 3.7
17500 -13.1 8.4 270 57 29 7.2 4.0 | -12.9 8.8 270 54 28 7.1 3.9
17000 -12.0 10.4 270 56 29 7.4 4.1 | -11.9 10.6 270 53 28 7.3 4.0
16500 -10.9 12.4 270 55 28 7.5 4.1 | -10.9 12.4 265 53 27 7.7 4.2
16000 -9.8 14.4 270 53 27 7.5 4.1 | -9.7 14.5 265 50 26 8.7 4.8
15500 -8.7 16.3 270 51 26 7.5 4.1 | -8.4 16.9 265 47 24 8.7 4.8
15000 -7.6 18.3 265 49 25 8.3 4.5 | -7.1 19.2 260 45 23 9.5 5.2
14500 -6.4 20.5 265 46 24 8.3 4.6 | -5.7 21.7 260 43 22 9.4 5.2
14000 -5.2 22.6 260 44 23 8.9 4.9 | -4.3 24.3 260 42 22 9.5 5.2
13500 -3.8 25.2 260 43 22 9.2 5.1 | -2.9 26.8 260 41 21 9.5 5.2
13000 -2.5 27.5 260 42 22 10.1 5.6 | -1.5 29.3 260 41 21 10.7 5.9
12500 -0.9 30.4 260 42 21 8.6 4.7 | -0.0 32.0 260 39 20 8.2 4.5
12000 0.3 32.5 260 41 21 7.1 3.9 | 1.1 34.0 260 36 18 7.3 4.0
11750 0.7 33.3 260 40 20 5.6 3.1 | 1.6 34.9 260 34 18 6.7 3.7
11500 1.1 34.0 255 39 20 4.2 2.3 | 2.1 35.8 260 32 17 6.5 3.6
11250 1.3 34.3 255 37 19 3.9 2.1 | 2.7 36.9 260 30 15 9.6 5.3
11000 1.5 34.7 250 35 18 -4.5 -2.4 | 3.2 37.8 260 27 14 -1.5 -0.8
10750 0.6 33.1 250 32 16 -14.9 -8.2 | 2.4 36.3 255 25 13 -12.4 -6.8
10500 -0.5 31.1 245 28 15 -12.4 -6.8 | 1.7 35.1 255 23 12 -9.2 -5.1
10250 -1.5 29.3 235 25 13 -20.2 -11.1 | 0.9 33.6 245 21 11 -11.1 -6.1
10000 -3.1 26.4 230 22 12 -13.9 -7.6 | 0.0 32.0 240 20 10 -11.0 -6.0
9750 -3.4 25.9 220 20 10 -0.7 -0.4 | -0.7 30.7 230 17 9 -9.7 -5.3
9500 -3.6 25.5 210 17 9 -4.3 -2.4 | -1.5 29.3 220 15 8 -11.0 -6.1
9250 -3.9 25.0 195 16 8 -0.5 -0.3 | -2.2 28.0 205 14 7 -7.0 -3.8
9000 -3.6 25.5 180 15 8 6.0 3.3 | -2.4 27.7 185 13 7 2.4 1.3
8750 -3.1 26.4 170 15 8 8.1 4.4 | -2.0 28.4 175 12 6 5.3 2.9
8500 -2.5 27.5 165 14 7 7.3 4.0 | -1.7 28.9 165 12 6 4.2 2.3
8250 -2.0 28.4 155 14 7 8.3 4.6 | -1.3 29.7 150 12 6 5.8 3.2
8000 -1.2 29.8 155 14 7 14.4 7.9 | -0.7 30.7 150 12 6 12.0 6.6
7750 0.2 32.4 150 12 6 21.7 11.9 | 0.5 32.9 145 11 6 18.1 9.9
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.
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