Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
885
UXUS97 KBOU 031324
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0723 MDT Friday, May 3, 2024
This forecast is for Friday, May 3, 2024:
If the trigger temperature of 62.6 F/17.0 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1364 ft/min (6.9 m/s)
Maximum height of thermals.................. 19636 ft MSL (14302 ft AGL)
Forecast maximum temperature................... 72.0 F/22.7 C
Time of trigger temperature.................... 1000 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................. 14314 ft MSL (8980 ft AGL)
Thermal soaring outlook for Saturday 05/04..... Fair
Wave Soaring Index............................. Good
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 PVA
Potential height of wave....................... 16637 ft MSL (11303 ft AGL)
Wave soaring outlook for Saturday 05/04........ Poor
Remarks... Cold front expected between 3-7pm this afternoon
Sunrise/Sunset.................... 05:56:27 / 19:56:07 MDT
Total possible sunshine........... 13 hr 59 min 40 sec (839 min 40 sec)
Altitude of sun at 12:56:17 MDT... 66.21 degrees
Upper air data from numerical model forecast valid on 05/03/2024 at 0600 MDT
Freezing level.................. 11378 ft MSL (6044 ft AGL)
Convective condensation level... 14931 ft MSL (9597 ft AGL)
Lifted condensation level....... 16239 ft MSL (10905 ft AGL)
Lifted index.................... -1.6
K index......................... +11.3
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 -53.3 -63.9 250 36 19 0.1 0.0 M M M M M
45000 -53.2 -63.8 250 45 23 -1.5 -0.8 M M M M M
40000 -56.9 -70.4 255 67 34 -2.4 -1.3 M M M M M
38000 -56.9 -70.4 255 73 37 2.8 1.6 M M M M M
36000 -55.2 -67.4 260 76 39 2.8 1.6 M M M M M
34000 -53.2 -63.8 260 78 40 7.3 4.0 M M M M M
32000 -48.9 -56.0 260 73 38 7.1 3.9 M M M M M
30000 -44.0 -47.2 260 68 35 7.9 4.3 31.4 88.5 6.9 M M
29000 -41.6 -42.9 260 65 34 7.9 4.3 30.6 87.0 6.4 M M
28000 -39.2 -38.6 260 63 32 7.9 4.3 29.9 85.8 5.9 M M
27000 -36.9 -34.4 265 60 31 7.9 4.3 29.3 84.8 5.5 M M
26000 -34.5 -30.1 260 57 29 7.9 4.3 28.5 83.3 5.0 M M
25000 -32.2 -26.0 260 54 28 7.9 4.3 27.8 82.0 4.5 M M
24000 -29.8 -21.6 260 51 26 7.7 4.2 27.2 81.0 4.0 M M
23000 -27.8 -18.0 260 48 25 6.4 3.5 26.0 78.7 3.1 M M
22000 -25.9 -14.6 260 44 23 6.4 3.5 24.7 76.5 2.1 M M
21000 -24.0 -11.2 260 41 21 6.9 3.8 23.7 74.6 1.1 M M
20000 -21.8 -7.2 265 39 20 7.4 4.0 22.7 72.9 0.3 M M
19500 -20.8 -5.4 265 38 20 7.4 4.0 22.3 72.1 -0.0 1359 6.9
19000 -19.7 -3.5 265 37 19 7.4 4.1 21.9 71.4 -0.4 1311 6.7
18500 -18.6 -1.5 265 37 19 7.6 4.2 21.5 70.8 -0.7 1264 6.4
18000 -17.4 0.7 265 37 19 8.2 4.5 21.2 70.2 -1.0 1214 6.2
17500 -16.2 2.8 265 38 19 8.2 4.5 21.0 69.7 -1.3 1163 5.9
17000 -14.4 6.1 265 38 20 8.0 4.4 20.5 69.0 -1.7 1087 5.5
16500 -13.2 8.2 265 39 20 8.0 4.4 20.2 68.4 -2.0 1037 5.3
16000 -12.0 10.4 265 39 20 8.2 4.5 20.0 67.9 -2.2 986 5.0
15500 -10.8 12.6 265 39 20 8.2 4.5 19.7 67.5 -2.5 935 4.8
15000 -9.6 14.7 260 39 20 8.6 4.7 19.5 67.1 -2.8 884 4.5
14500 -8.3 17.1 260 38 20 8.6 4.7 19.3 66.7 -3.0 830 4.2
14000 -7.0 19.4 260 37 19 8.9 4.9 19.1 66.4 -3.1 777 3.9
13500 -5.7 21.7 260 37 19 9.0 5.0 19.0 66.2 -3.3 722 3.7
13000 -4.3 24.3 255 36 18 9.1 5.0 18.9 66.0 -3.4 667 3.4
12500 -3.0 26.6 255 35 18 9.1 5.0 18.8 65.8 -3.5 611 3.1
12000 -1.6 29.1 255 34 18 9.0 4.9 18.7 65.6 -3.6 556 2.8
11500 -0.3 31.5 250 34 17 8.9 4.9 18.5 65.3 -3.8 501 2.5
11000 1.1 34.0 250 33 17 8.3 4.5 18.4 65.1 -3.9 446 2.3
10500 2.1 35.8 245 32 16 6.5 3.5 18.0 64.4 -4.3 399 2.0
10250 2.7 36.9 245 31 16 8.5 4.7 17.8 64.0 -4.5 376 1.9
10000 3.4 38.1 245 30 15 9.9 5.4 17.8 64.0 -4.5 346 1.8
9750 4.0 39.2 240 29 15 7.7 4.2 17.7 63.9 -4.6 320 1.6
9500 4.6 40.3 240 28 14 6.9 3.8 17.5 63.5 -4.9 297 1.5
9250 5.1 41.2 235 27 14 7.7 4.2 17.3 63.1 -5.1 274 1.4
9000 5.6 42.1 235 26 13 5.3 2.9 17.1 62.8 -5.3 250 1.3
8750 5.9 42.6 235 26 13 4.0 2.2 16.6 61.9 -5.8 235 1.2
8500 6.2 43.2 230 25 13 5.3 2.9 16.3 61.3 -6.2 217 1.1
8250 6.6 43.9 225 24 12 5.0 2.7 15.9 60.6 -6.6 200 1.0
8000 6.9 44.4 220 23 12 3.7 2.0 15.5 59.9 -7.0 183 0.9
7750 7.1 44.8 220 23 12 1.8 1.0 15.0 58.9 -7.6 171 0.9
7500 7.1 44.8 215 23 12 1.5 0.8 14.3 57.8 -8.3 162 0.8
7250 7.2 45.0 205 23 12 1.4 0.8 13.7 56.7 -9.0 153 0.8
7000 7.2 45.0 200 24 12 1.3 0.7 13.1 55.5 -9.7 144 0.7
6750 7.2 45.0 195 25 13 -1.1 -0.6 12.4 54.3 -10.4 135 0.7
6500 7.0 44.6 190 25 13 -3.3 -1.8 11.4 52.5 -11.4 135 0.7
6250 6.8 44.2 185 25 13 -0.9 -0.5 10.5 50.9 -12.4 134 0.7
6000 6.8 44.2 180 23 12 -0.3 -0.2 9.7 49.5 -13.2 127 0.6
5750 6.7 44.1 180 22 11 1.5 0.8 9.0 48.2 -13.9 121 0.6
5500 6.9 44.4 175 15 8 0.8 0.5 8.4 47.2 -14.6 109 0.6
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/03/2024 at 0900 MDT | 05/03/2024 at 1200 MDT
|
CAPE... +7.8 LI... +1.6 | CAPE... +11.5 LI... +0.4
CINH... -38.6 K Index... +8.1 | CINH... -3.5 K Index... +14.1
|
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 -53.4 -64.1 245 35 18 -0.1 -0.1 | -53.6 -64.5 245 37 19 -0.3 -0.2
45000 -53.6 -64.5 250 49 25 -2.0 -1.1 | -54.2 -65.6 245 51 26 -2.3 -1.3
40000 -58.0 -72.4 255 68 35 -3.0 -1.6 | -59.3 -74.7 255 70 36 -3.4 -1.9
38000 -57.8 -72.0 255 70 36 3.8 2.1 | -58.8 -73.8 255 71 36 5.0 2.8
36000 -55.5 -67.9 260 68 35 3.8 2.1 | -55.8 -68.4 255 66 34 5.0 2.8
34000 -53.0 -63.4 260 65 33 7.6 4.2 | -52.5 -62.5 255 61 31 7.6 4.2
32000 -48.6 -55.5 255 61 31 7.2 4.0 | -47.5 -53.5 255 58 30 7.4 4.1
30000 -43.6 -46.5 250 57 30 8.3 4.6 | -42.9 -45.2 250 56 29 8.2 4.5
29000 -41.1 -42.0 250 56 29 8.3 4.6 | -40.4 -40.7 250 55 28 8.2 4.5
28000 -38.6 -37.5 250 56 29 8.3 4.6 | -38.0 -36.4 250 54 28 8.2 4.5
27000 -36.1 -33.0 245 55 28 8.2 4.5 | -35.5 -31.9 250 54 28 7.8 4.3
26000 -33.7 -28.7 245 54 28 8.1 4.4 | -33.2 -27.8 250 54 28 7.7 4.2
25000 -31.3 -24.3 250 53 27 8.1 4.4 | -30.9 -23.6 250 54 28 7.7 4.2
24000 -28.8 -19.8 250 53 27 7.8 4.3 | -28.6 -19.5 250 54 28 7.3 4.0
23000 -26.7 -16.1 250 50 26 7.0 3.9 | -26.7 -16.1 250 51 26 6.4 3.5
22000 -24.6 -12.3 250 47 24 7.0 3.9 | -24.8 -12.6 250 49 25 6.4 3.5
21000 -22.5 -8.5 250 45 23 6.7 3.7 | -22.9 -9.2 250 46 24 6.9 3.8
20000 -20.6 -5.1 250 41 21 6.5 3.6 | -20.8 -5.4 245 43 22 7.0 3.9
19500 -19.6 -3.3 250 40 20 6.5 3.6 | -19.7 -3.5 245 42 22 7.1 3.9
19000 -18.7 -1.7 250 38 20 6.6 3.6 | -18.7 -1.7 245 41 21 7.1 3.9
18500 -17.7 0.1 250 36 19 6.8 3.8 | -17.6 0.3 245 39 20 7.3 4.0
18000 -16.7 1.9 255 35 18 7.3 4.0 | -16.5 2.3 245 38 20 7.5 4.1
17500 -15.6 3.9 255 34 17 7.3 4.0 | -15.4 4.3 245 37 19 7.5 4.1
17000 -13.9 7.0 255 33 17 7.7 4.2 | -14.3 6.3 245 36 18 7.7 4.2
16500 -12.8 9.0 260 33 17 7.7 4.2 | -12.6 9.3 245 33 17 7.8 4.3
16000 -11.6 11.1 260 34 17 8.2 4.5 | -11.3 11.7 245 32 16 9.1 5.0
15500 -10.4 13.3 260 35 18 8.2 4.5 | -10.0 14.0 245 31 16 9.0 4.9
15000 -9.2 15.4 260 35 18 8.1 4.4 | -8.6 16.5 245 30 15 9.4 5.1
14500 -8.0 17.6 260 34 18 8.1 4.4 | -7.2 19.0 245 29 15 9.4 5.1
14000 -6.8 19.8 260 33 17 8.4 4.6 | -5.8 21.6 245 28 15 9.3 5.1
13500 -5.5 22.1 260 32 17 8.6 4.7 | -4.4 24.1 245 28 14 9.3 5.1
13000 -4.2 24.4 260 31 16 8.6 4.7 | -3.0 26.6 245 27 14 9.3 5.1
12500 -3.0 26.6 260 30 16 8.6 4.7 | -1.7 28.9 245 26 14 9.3 5.1
12000 -1.7 28.9 260 29 15 8.8 4.8 | -0.3 31.5 245 25 13 9.4 5.1
11500 -0.3 31.5 260 28 14 9.1 5.0 | 1.1 34.0 240 24 13 9.4 5.2
11000 1.0 33.8 260 26 14 8.5 4.7 | 2.5 36.5 240 23 12 8.7 4.8
10500 2.2 36.0 255 26 13 7.0 3.9 | 3.7 38.7 240 22 11 7.0 3.8
10250 2.7 36.9 255 26 13 9.9 5.4 | 4.3 39.7 240 21 11 11.4 6.3
10000 3.6 38.5 255 25 13 11.2 6.1 | 5.4 41.7 240 21 11 12.3 6.7
9750 4.3 39.7 255 25 13 8.6 4.7 | 6.0 42.8 240 20 11 8.3 4.6
9500 5.0 41.0 255 24 12 9.0 4.9 | 6.7 44.1 240 20 10 8.7 4.8
9250 5.6 42.1 250 23 12 8.1 4.5 | 7.4 45.3 235 19 10 10.3 5.6
9000 6.2 43.2 250 23 12 7.6 4.2 | 8.2 46.8 235 19 10 10.9 6.0
8750 6.8 44.2 250 22 11 8.6 4.7 | 8.9 48.0 235 18 9 9.5 5.2
8500 7.5 45.5 245 21 11 9.0 5.0 | 9.7 49.5 235 18 9 10.1 5.6
8250 8.1 46.6 245 20 11 8.3 4.6 | 10.4 50.7 235 17 9 9.1 5.0
8000 8.7 47.7 240 20 10 6.5 3.5 | 11.1 52.0 235 17 9 8.6 4.7
7750 9.1 48.4 240 19 10 6.3 3.5 | 11.8 53.2 235 17 9 10.2 5.6
7500 9.6 49.3 235 18 9 7.8 4.3 | 12.6 54.7 235 16 8 11.3 6.2
7250 10.1 50.2 230 18 9 5.1 2.8 | 13.4 56.1 235 16 8 9.3 5.1
7000 10.3 50.5 225 18 9 1.5 0.8 | 14.0 57.2 235 16 8 7.2 4.0
6750 10.4 50.7 220 18 9 2.3 1.3 | 14.6 58.3 235 15 8 10.6 5.8
6500 10.6 51.1 210 17 9 3.2 1.8 | 15.5 59.9 235 14 7 13.0 7.1
6250 10.8 51.4 205 17 9 3.6 2.0 | 16.4 61.5 235 14 7 10.7 5.8
6000 11.0 51.8 200 16 8 3.7 2.0 | 17.1 62.8 235 13 7 9.5 5.2
5750 11.3 52.3 195 16 8 5.7 3.1 | 17.9 64.2 235 13 7 10.1 5.6
5500 11.9 53.4 190 13 7 13.1 7.2 | 18.8 65.8 235 11 6 16.7 9.1
05/03/2024 at 1500 MDT | 05/03/2024 at 1800 MDT
|
CAPE... +40.1 LI... -0.2 | CAPE... +69.6 LI... -0.1
CINH... -4.2 K Index... +14.9 | CINH... -18.7 K Index... +20.2
|
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 -54.7 -66.5 250 38 20 0.1 0.0 | -54.2 -65.6 250 35 18 0.8 0.4
45000 -54.6 -66.3 250 56 29 -1.9 -1.1 | -53.1 -63.6 255 53 27 -2.1 -1.2
40000 -59.0 -74.2 255 69 35 -2.9 -1.6 | -59.1 -74.4 255 66 34 -4.0 -2.2
38000 -58.5 -73.3 255 69 35 4.6 2.5 | -58.8 -73.8 255 67 35 4.9 2.7
36000 -55.7 -68.3 255 64 33 4.7 2.6 | -55.8 -68.4 255 65 33 4.9 2.7
34000 -52.6 -62.7 255 61 31 7.8 4.3 | -52.1 -61.8 255 62 32 7.3 4.0
32000 -47.5 -53.5 250 59 31 7.5 4.1 | -47.7 -53.9 250 61 31 7.4 4.1
30000 -42.9 -45.2 250 58 30 8.1 4.4 | -43.1 -45.6 250 60 31 8.0 4.4
29000 -40.4 -40.7 250 57 29 8.1 4.4 | -40.7 -41.3 250 60 31 8.0 4.4
28000 -38.0 -36.4 250 57 29 8.1 4.4 | -38.3 -36.9 250 59 30 8.0 4.4
27000 -35.6 -32.1 250 56 29 7.4 4.0 | -35.9 -32.6 250 59 30 7.5 4.1
26000 -33.5 -28.3 250 54 28 7.1 3.9 | -33.8 -28.8 250 56 29 7.3 4.0
25000 -31.4 -24.5 250 52 27 7.1 3.9 | -31.6 -24.9 245 53 27 7.3 4.0
24000 -29.2 -20.6 250 50 26 7.1 3.9 | -29.4 -20.9 245 51 26 7.2 3.9
23000 -27.1 -16.8 245 46 24 7.2 3.9 | -27.3 -17.1 240 47 24 6.9 3.8
22000 -25.0 -13.0 245 42 22 7.2 3.9 | -25.3 -13.5 235 42 22 7.0 3.8
21000 -22.8 -9.0 240 39 20 7.7 4.2 | -23.2 -9.8 230 39 20 7.9 4.3
20000 -20.5 -4.9 240 37 19 7.8 4.3 | -20.8 -5.4 230 36 19 8.2 4.5
19500 -19.4 -2.9 240 36 18 7.8 4.3 | -19.6 -3.3 230 35 18 8.2 4.5
19000 -18.3 -0.9 240 35 18 7.8 4.3 | -18.4 -1.1 230 34 17 8.2 4.5
18500 -17.1 1.2 240 34 17 8.2 4.5 | -16.6 2.1 230 32 16 8.1 4.4
18000 -15.8 3.6 240 32 17 8.4 4.6 | -15.4 4.3 230 30 16 8.1 4.5
17500 -14.6 5.7 235 31 16 8.4 4.6 | -14.2 6.4 230 29 15 8.3 4.6
17000 -13.3 8.1 235 30 16 9.1 5.0 | -12.9 8.8 235 28 14 8.5 4.7
16500 -11.3 11.7 240 29 15 9.1 5.0 | -11.6 11.1 235 27 14 8.6 4.7
16000 -9.9 14.2 240 29 15 9.4 5.2 | -10.3 13.5 235 26 13 9.3 5.1
15500 -8.5 16.7 240 28 14 9.4 5.2 | -8.9 16.0 240 24 12 9.3 5.1
15000 -7.1 19.2 240 27 14 9.2 5.1 | -7.6 18.3 240 23 12 9.0 5.0
14500 -5.7 21.7 240 27 14 9.2 5.1 | -6.2 20.8 240 21 11 9.0 5.0
14000 -4.3 24.3 240 26 14 9.3 5.1 | -4.9 23.2 245 19 10 8.8 4.8
13500 -2.9 26.8 240 25 13 9.3 5.1 | -3.6 25.5 245 18 9 8.7 4.8
13000 -1.5 29.3 240 25 13 9.4 5.2 | -2.3 27.9 250 16 8 8.4 4.6
12500 -0.1 31.8 240 24 12 9.5 5.2 | -1.1 30.0 255 14 7 8.2 4.5
12000 1.3 34.3 240 23 12 9.6 5.2 | 0.1 32.2 265 13 7 7.9 4.3
11500 2.7 36.9 245 22 11 9.6 5.2 | 1.3 34.3 275 12 6 7.5 4.1
11000 4.2 39.6 245 22 11 8.8 4.8 | 2.4 36.3 290 11 6 7.1 3.9
10500 5.4 41.7 245 21 11 6.8 3.7 | 3.4 38.1 305 11 6 6.3 3.5
10250 6.0 42.8 245 21 11 12.1 6.6 | 3.9 39.0 310 11 6 8.3 4.6
10000 7.1 44.8 245 21 11 13.3 7.3 | 4.5 40.1 315 12 6 8.9 4.9
9750 7.8 46.0 245 21 11 8.6 4.7 | 5.1 41.2 325 12 6 7.2 4.0
9500 8.5 47.3 250 20 11 9.2 5.0 | 5.7 42.3 330 13 6 7.5 4.1
9250 9.2 48.6 250 20 10 10.3 5.6 | 6.2 43.2 335 13 7 7.5 4.1
9000 10.0 50.0 250 20 10 10.7 5.9 | 6.8 44.2 340 14 7 6.9 3.8
8750 10.8 51.4 250 20 10 9.6 5.3 | 7.2 45.0 345 15 8 6.5 3.6
8500 11.5 52.7 250 19 10 10.1 5.6 | 7.7 45.9 350 16 8 6.4 3.5
8250 12.2 54.0 250 19 10 9.2 5.0 | 8.2 46.8 350 17 9 7.1 3.9
8000 12.9 55.2 250 19 10 8.8 4.8 | 8.7 47.7 355 18 9 8.5 4.7
7750 13.6 56.5 255 19 10 10.1 5.5 | 9.4 48.9 355 18 9 8.0 4.4
7500 14.4 57.9 255 18 9 11.0 6.0 | 9.9 49.8 355 19 10 7.1 3.9
7250 15.2 59.4 255 18 9 9.5 5.2 | 10.5 50.9 360 20 10 8.2 4.5
7000 15.8 60.4 255 18 9 8.0 4.4 | 11.1 52.0 360 20 10 9.3 5.1
6750 16.5 61.7 255 18 9 10.3 5.7 | 11.8 53.2 360 20 10 9.2 5.0
6500 17.3 63.1 255 17 9 12.3 6.8 | 12.5 54.5 360 21 11 9.2 5.1
6250 18.2 64.8 255 16 8 10.5 5.8 | 13.2 55.8 360 21 11 10.6 5.8
6000 18.9 66.0 255 16 8 9.4 5.2 | 14.1 57.4 360 20 10 12.3 6.7
5750 19.7 67.5 260 15 8 10.3 5.6 | 14.9 58.8 360 19 10 8.7 4.8
5500 20.6 69.1 260 13 7 16.3 8.9 | 15.4 59.7 360 17 9 7.3 4.0
________________________________________________________________________________
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.
CINH (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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