Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
414
UXUS97 KBOU 031315
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0714 MDT Wednesday, July 3, 2024
This forecast is for Wednesday, July 3, 2024:
If the trigger temperature of 77.2 F/25.1 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1048 ft/min (5.3 m/s)
Maximum height of thermals.................. 17552 ft MSL (12216 ft AGL)
Forecast maximum temperature................... 91.0 F/33.2 C
Time of trigger temperature.................... 0945 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................. 14980 ft MSL (9644 ft AGL)
Thermal soaring outlook for Thursday 07/04..... Good
Wave Soaring Index............................. Poor
Wave Soaring Index trend (to 1800 MDT)......... No change
Height of stable layer (12-18K ft MSL)......... None
Weak PVA/NVA (through 1800 MDT)................ Weak PVA
Potential height of wave....................... 21593 ft MSL (16257 ft AGL)
Wave soaring outlook for Thursday 07/04........ Poor
Remarks...
Sunrise/Sunset.................... 05:36:39 / 20:31:08 MDT
Total possible sunshine........... 14 hr 54 min 28 sec (894 min 28 sec)
Altitude of sun at 13:03:54 MDT... 73.08 degrees
Upper air data from numerical model forecast valid on 07/03/2024 at 0600 MDT
Freezing level.................. 15240 ft MSL (9904 ft AGL)
Convective condensation level... 13506 ft MSL (8170 ft AGL)
Lifted condensation level....... 15397 ft MSL (10060 ft AGL)
Lifted index.................... -6.4
K index......................... +18.7
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 -59.8 -75.6 260 38 20 3.2 1.7 M M M M M
45000 -53.9 -65.0 255 50 26 5.4 3.0 M M M M M
40000 -46.0 -50.8 240 70 36 3.5 1.9 M M M M M
38000 -43.9 -47.0 240 67 34 3.5 1.9 M M M M M
36000 -41.5 -42.7 240 63 33 3.4 1.9 M M M M M
34000 -39.0 -38.2 240 60 31 4.4 2.4 M M M M M
32000 -36.3 -33.3 240 57 29 4.4 2.4 M M M M M
30000 -32.9 -27.2 240 51 26 6.1 3.3 42.6 108.6 7.5 M M
29000 -31.1 -24.0 240 48 25 6.1 3.3 41.2 106.1 6.5 M M
28000 -29.3 -20.7 240 46 23 6.9 3.8 39.9 103.8 5.5 M M
27000 -26.8 -16.2 240 44 22 8.5 4.7 39.2 102.6 5.1 M M
26000 -24.2 -11.6 240 41 21 8.5 4.7 38.8 101.8 4.7 M M
25000 -21.7 -7.1 240 39 20 8.5 4.7 38.4 101.1 4.5 M M
24000 -19.2 -2.6 240 37 19 8.3 4.5 37.8 100.1 4.1 M M
23000 -16.7 1.9 245 35 18 8.3 4.5 37.3 99.1 3.7 M M
22000 -14.2 6.4 245 33 17 8.3 4.6 36.8 98.2 3.3 M M
21000 -11.9 10.6 250 31 16 7.7 4.2 36.1 96.9 2.7 M M
20000 -9.6 14.7 255 30 15 7.7 4.2 35.3 95.6 2.1 M M
19500 -8.4 16.9 255 29 15 7.7 4.2 35.0 95.0 1.8 M M
19000 -6.8 19.8 260 28 14 6.6 3.6 34.4 93.9 1.3 M M
18500 -5.8 21.6 265 27 14 6.7 3.7 33.9 93.0 0.9 M M
18000 -4.8 23.4 265 27 14 6.3 3.4 33.3 92.0 0.4 M M
17500 -3.9 25.0 270 26 13 6.0 3.3 32.7 90.8 -0.2 1036 5.3
17000 -3.0 26.6 270 25 13 6.0 3.3 32.1 89.7 -0.7 994 5.1
16500 -2.2 28.0 275 24 13 6.1 3.4 31.4 88.6 -1.3 953 4.8
16000 -1.3 29.7 275 24 12 6.2 3.4 30.8 87.5 -1.9 913 4.6
15500 -0.4 31.3 275 23 12 6.9 3.8 30.3 86.5 -2.5 871 4.4
15000 0.6 33.1 275 22 11 7.1 3.9 29.8 85.7 -3.0 827 4.2
14500 1.6 34.9 280 21 11 7.8 4.3 29.4 85.0 -3.5 783 4.0
14000 2.7 36.9 275 19 10 8.2 4.5 29.2 84.5 -3.9 733 3.7
13500 3.9 39.0 275 18 9 8.2 4.5 28.9 84.1 -4.2 683 3.5
13000 5.0 41.0 270 17 9 8.0 4.4 28.6 83.5 -4.6 635 3.2
12500 6.1 43.0 270 15 8 8.0 4.4 28.4 83.0 -5.0 587 3.0
12000 7.2 45.0 265 13 7 7.7 4.2 28.0 82.5 -5.4 540 2.7
11500 8.3 46.9 255 12 6 7.8 4.3 27.7 81.9 -5.8 493 2.5
11000 9.4 48.9 245 11 5 8.2 4.5 27.5 81.4 -6.1 444 2.3
10500 10.6 51.1 240 10 5 5.6 3.1 27.2 81.0 -6.5 395 2.0
10250 10.8 51.4 235 10 5 4.8 2.7 26.8 80.2 -6.9 379 1.9
10000 11.4 52.5 235 10 5 9.4 5.2 26.6 79.9 -7.1 355 1.8
9750 12.1 53.8 230 10 5 10.0 5.5 26.6 79.9 -7.2 327 1.7
9500 12.8 55.0 225 9 5 9.5 5.2 26.6 79.9 -7.2 299 1.5
9250 13.3 55.9 225 10 5 6.4 3.5 26.5 79.7 -7.4 274 1.4
9000 13.7 56.7 220 10 5 6.5 3.6 26.2 79.1 -7.8 255 1.3
8750 14.3 57.7 215 10 5 8.7 4.8 26.1 78.9 -7.9 230 1.2
8500 14.9 58.8 215 10 5 7.6 4.1 25.9 78.7 -8.1 205 1.0
8250 15.4 59.7 210 10 5 6.1 3.3 25.7 78.3 -8.3 183 0.9
8000 15.8 60.4 210 11 6 5.4 3.0 25.4 77.7 -8.7 164 0.8
7750 16.2 61.2 205 12 6 5.9 3.2 25.1 77.2 -9.0 144 0.7
7500 16.6 61.9 205 12 6 5.1 2.8 24.8 76.6 -9.3 124 0.6
7250 16.9 62.4 200 13 7 4.0 2.2 24.4 75.9 -9.8 107 0.5
7000 17.2 63.0 200 13 7 4.0 2.2 23.9 75.1 -10.3 91 0.5
6750 17.5 63.5 195 14 7 4.1 2.3 23.5 74.3 -10.7 75 0.4
6500 17.8 64.0 190 15 8 3.1 1.7 23.0 73.5 -11.2 60 0.3
6250 17.9 64.2 190 14 7 1.9 1.1 22.5 72.4 -11.8 47 0.2
6000 18.1 64.6 185 12 6 2.9 1.6 21.9 71.4 -12.4 35 0.2
5750 18.3 64.9 185 11 5 -0.7 -0.4 21.3 70.4 -13.0 23 0.1
5500 17.9 64.2 180 7 4 -9.2 -5.1 20.2 68.4 -14.1 27 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/03/2024 at 0900 MDT | 07/03/2024 at 1200 MDT
|
CAPE... +772.2 LI... -2.2 | CAPE... +447.9 LI... -1.6
CINH... -76.2 K Index... +11.2 | CINH... -18.8 K Index... +18.6
|
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 -59.2 -74.6 265 41 21 2.6 1.4 | -59.2 -74.6 265 39 20 2.5 1.4
45000 -53.9 -65.0 255 52 27 5.5 3.0 | -53.8 -64.8 260 56 29 5.9 3.2
40000 -45.9 -50.6 245 67 35 3.4 1.9 | -45.3 -49.5 255 70 36 3.3 1.8
38000 -43.8 -46.8 240 64 33 3.4 1.9 | -43.3 -45.9 250 66 34 3.4 1.8
36000 -41.5 -42.7 240 60 31 3.3 1.8 | -41.0 -41.8 245 63 33 3.3 1.8
34000 -38.9 -38.0 240 56 29 4.5 2.5 | -38.3 -36.9 245 60 31 4.8 2.6
32000 -36.2 -33.2 240 53 27 4.5 2.5 | -35.4 -31.7 245 57 29 4.8 2.6
30000 -33.1 -27.6 240 50 26 5.3 2.9 | -32.6 -26.7 245 51 26 4.7 2.6
29000 -31.5 -24.7 235 49 25 5.4 2.9 | -31.2 -24.2 240 47 24 4.7 2.6
28000 -29.9 -21.8 235 47 24 6.2 3.4 | -29.8 -21.6 240 44 23 5.2 2.8
27000 -27.5 -17.5 240 45 23 8.3 4.5 | -27.7 -17.9 245 42 22 7.2 4.0
26000 -25.0 -13.0 240 42 22 8.3 4.5 | -25.6 -14.1 245 40 21 7.2 4.0
25000 -22.5 -8.5 240 40 21 8.3 4.6 | -23.4 -10.1 250 39 20 7.2 3.9
24000 -20.1 -4.2 245 38 19 7.9 4.3 | -21.1 -6.0 250 38 20 7.8 4.3
23000 -17.8 -0.0 250 36 18 7.9 4.4 | -18.8 -1.8 255 38 19 7.9 4.3
22000 -15.4 4.3 255 34 17 8.0 4.4 | -16.4 2.5 260 37 19 7.9 4.3
21000 -13.1 8.4 260 32 17 7.7 4.2 | -14.1 6.6 265 37 19 7.9 4.3
20000 -10.8 12.6 265 31 16 7.7 4.2 | -11.8 10.8 265 36 18 7.9 4.3
19500 -9.7 14.5 270 30 16 7.7 4.2 | -10.6 12.9 265 35 18 7.9 4.4
19000 -8.0 17.6 275 30 15 7.1 3.9 | -9.4 15.1 265 35 18 8.1 4.4
18500 -6.9 19.6 275 29 15 7.2 3.9 | -8.2 17.2 270 34 17 8.1 4.5
18000 -5.8 21.6 280 29 15 7.1 3.9 | -6.4 20.5 270 33 17 8.2 4.5
17500 -4.8 23.4 280 29 15 7.1 3.9 | -5.2 22.6 270 32 17 8.2 4.5
17000 -3.7 25.3 280 28 14 7.1 3.9 | -4.0 24.8 270 32 16 8.2 4.5
16500 -2.6 27.3 280 27 14 7.4 4.1 | -2.8 27.0 270 31 16 8.2 4.5
16000 -1.6 29.1 280 26 14 7.4 4.1 | -1.6 29.1 270 30 16 8.2 4.5
15500 -0.4 31.3 280 25 13 8.2 4.5 | -0.3 31.5 270 29 15 8.6 4.7
15000 0.8 33.4 280 24 12 8.2 4.5 | 0.9 33.6 270 28 14 8.7 4.8
14500 2.0 35.6 280 23 12 8.4 4.6 | 2.2 36.0 270 27 14 8.7 4.7
14000 3.2 37.8 280 22 11 8.5 4.6 | 3.4 38.1 275 25 13 8.6 4.7
13500 4.5 40.1 280 21 11 8.5 4.7 | 4.7 40.5 275 23 12 8.7 4.7
13000 5.7 42.3 280 20 10 8.6 4.7 | 6.0 42.8 275 21 11 8.7 4.8
12500 7.0 44.6 280 18 9 8.5 4.7 | 7.2 45.0 275 19 10 8.7 4.8
12000 8.2 46.8 280 17 9 8.2 4.5 | 8.5 47.3 275 17 9 8.7 4.8
11500 9.4 48.9 280 15 8 8.2 4.5 | 9.8 49.6 275 15 8 8.6 4.7
11000 10.5 50.9 275 14 7 7.7 4.2 | 11.0 51.8 275 12 6 8.0 4.4
10500 11.7 53.1 275 12 6 5.0 2.7 | 12.2 54.0 275 10 5 3.8 2.1
10250 11.9 53.4 275 12 6 5.2 2.8 | 12.3 54.1 270 8 4 5.6 3.1
10000 12.5 54.5 275 11 6 9.8 5.4 | 13.1 55.6 270 7 4 12.6 6.9
9750 13.1 55.6 270 10 5 9.5 5.2 | 13.9 57.0 270 7 3 11.1 6.1
9500 13.8 56.8 265 9 5 9.0 5.0 | 14.7 58.5 265 6 3 10.2 5.6
9250 14.3 57.7 265 9 5 6.5 3.6 | 15.3 59.5 265 5 2 6.9 3.8
9000 14.7 58.5 260 9 5 6.5 3.6 | 15.8 60.4 260 4 2 9.1 5.0
8750 15.3 59.5 255 9 4 8.0 4.4 | 16.7 62.1 265 3 2 11.8 6.5
8500 15.8 60.4 250 8 4 6.9 3.8 | 17.5 63.5 265 3 2 10.2 5.6
8250 16.2 61.2 245 9 4 5.1 2.8 | 18.1 64.6 265 2 1 7.2 3.9
8000 16.5 61.7 245 9 5 4.7 2.6 | 18.6 65.5 265 2 1 9.0 4.9
7750 16.9 62.4 235 9 5 5.1 2.8 | 19.5 67.1 270 1 1 13.0 7.1
7500 17.2 63.0 225 9 5 4.7 2.6 | 20.4 68.7 275 2 1 10.2 5.6
7250 17.5 63.5 220 8 4 3.9 2.2 | 21.0 69.8 280 1 1 6.8 3.8
7000 17.7 63.9 215 7 4 4.6 2.5 | 21.5 70.7 290 1 0 8.4 4.6
6750 18.1 64.6 210 7 3 8.1 4.4 | 22.3 72.1 300 1 0 13.6 7.5
6500 18.7 65.7 200 7 3 8.9 4.9 | 23.4 74.1 300 1 0 12.2 6.7
6250 19.3 66.7 195 6 3 7.7 4.2 | 24.1 75.4 325 1 0 9.1 5.0
6000 19.8 67.6 195 6 3 7.4 4.0 | 24.8 76.6 360 1 0 9.0 5.0
5750 20.5 68.9 195 5 3 12.5 6.8 | 25.6 78.1 010 1 0 15.0 8.2
5500 21.8 71.2 195 5 3 23.4 12.8 | 27.3 81.1 355 1 0 30.1 16.5
07/03/2024 at 1500 MDT | 07/03/2024 at 1800 MDT
|
CAPE... +358.0 LI... -1.6 | CAPE... +46.5 LI... -0.5
CINH... -3.0 K Index... +20.9 | CINH... -6.8 K Index... +16.1
|
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 39 20 3.6 2.0 | -60.5 -76.9 260 43 22 4.1 2.3
45000 -53.1 -63.6 265 54 28 4.7 2.6 | -53.6 -64.5 260 55 28 5.5 3.0
40000 -46.0 -50.8 250 70 36 4.8 2.6 | -45.6 -50.1 260 64 33 3.4 1.9
38000 -43.2 -45.8 255 67 35 4.8 2.6 | -43.5 -46.3 260 64 33 3.5 1.9
36000 -39.9 -39.8 255 63 33 4.9 2.7 | -41.1 -42.0 265 64 33 3.4 1.9
34000 -38.0 -36.4 255 60 31 3.0 1.6 | -38.9 -38.0 265 57 30 3.7 2.0
32000 -36.2 -33.2 255 56 29 3.1 1.7 | -36.7 -34.1 270 49 25 3.7 2.1
30000 -33.3 -27.9 260 50 26 5.3 2.9 | -33.0 -27.4 270 46 24 7.0 3.8
29000 -31.7 -25.1 260 47 24 5.4 2.9 | -30.9 -23.6 275 46 24 7.0 3.8
28000 -30.1 -22.2 260 44 23 5.6 3.1 | -28.8 -19.8 275 46 23 6.9 3.8
27000 -28.2 -18.8 260 42 21 6.7 3.7 | -26.7 -16.1 275 43 22 6.9 3.8
26000 -26.2 -15.2 260 39 20 6.7 3.7 | -24.6 -12.3 275 41 21 6.9 3.8
25000 -24.2 -11.6 255 37 19 6.7 3.7 | -22.6 -8.7 270 38 20 6.9 3.8
24000 -22.0 -7.6 255 35 18 7.9 4.3 | -20.5 -4.9 270 35 18 7.1 3.9
23000 -19.6 -3.3 255 34 17 7.9 4.4 | -18.4 -1.1 265 32 17 7.1 3.9
22000 -17.3 0.9 260 32 16 7.9 4.4 | -16.3 2.7 255 30 15 7.1 3.9
21000 -14.8 5.4 260 31 16 8.5 4.7 | -14.0 6.8 255 28 14 7.9 4.4
20000 -12.3 9.9 260 29 15 8.6 4.7 | -11.7 10.9 260 26 13 8.0 4.4
19500 -11.0 12.2 260 29 15 8.5 4.7 | -10.5 13.1 260 25 13 8.0 4.4
19000 -9.0 15.8 265 28 14 9.4 5.2 | -9.3 15.3 260 24 12 8.8 4.8
18500 -7.6 18.3 265 27 14 9.4 5.1 | -8.0 17.6 260 23 12 9.0 5.0
18000 -6.2 20.8 265 26 13 9.4 5.1 | -6.0 21.2 260 22 12 9.3 5.1
17500 -4.8 23.4 265 25 13 9.4 5.1 | -4.6 23.7 265 22 11 9.4 5.1
17000 -3.5 25.7 265 24 13 9.4 5.2 | -3.2 26.2 265 21 11 9.4 5.2
16500 -2.0 28.4 265 24 12 9.6 5.3 | -1.8 28.8 265 21 11 9.6 5.2
16000 -0.6 30.9 265 23 12 9.6 5.3 | -0.3 31.5 265 21 11 9.6 5.2
15500 0.8 33.4 265 22 11 9.5 5.2 | 1.1 34.0 270 20 11 9.5 5.2
15000 2.2 36.0 270 21 11 9.5 5.2 | 2.5 36.5 270 20 10 9.5 5.2
14500 3.6 38.5 270 20 10 9.4 5.2 | 3.9 39.0 270 20 10 9.5 5.2
14000 5.0 41.0 270 19 10 9.4 5.2 | 5.3 41.5 270 19 10 9.5 5.2
13500 6.4 43.5 270 18 9 9.3 5.1 | 6.8 44.2 275 19 10 9.5 5.2
13000 7.8 46.0 270 17 9 9.2 5.0 | 8.2 46.8 275 18 9 9.5 5.2
12500 9.2 48.6 275 16 8 9.2 5.0 | 9.6 49.3 275 18 9 9.5 5.2
12000 10.5 50.9 275 14 7 9.2 5.1 | 11.0 51.8 280 17 9 9.4 5.2
11500 11.9 53.4 280 13 7 9.2 5.0 | 12.4 54.3 280 17 9 9.3 5.1
11000 13.1 55.6 280 12 6 8.2 4.5 | 13.7 56.7 280 16 8 8.2 4.5
10500 14.2 57.6 285 12 6 12.5 6.8 | 14.8 58.6 285 16 8 12.7 7.0
10250 15.4 59.7 285 12 6 13.6 7.4 | 16.0 60.8 285 16 8 13.8 7.6
10000 16.1 61.0 285 12 6 8.6 4.7 | 16.7 62.1 285 16 8 8.6 4.7
9750 16.8 62.2 285 11 6 10.1 5.5 | 17.5 63.5 285 16 8 10.2 5.6
9500 17.5 63.5 285 11 6 9.0 5.0 | 18.2 64.8 290 17 9 8.9 4.9
9250 18.2 64.8 290 11 6 8.3 4.6 | 18.8 65.8 290 16 8 7.8 4.3
9000 18.8 65.8 290 10 5 9.8 5.4 | 19.5 67.1 290 16 8 9.7 5.3
8750 19.6 67.3 290 10 5 10.9 6.0 | 20.3 68.5 290 17 9 11.2 6.2
8500 20.4 68.7 290 10 5 10.3 5.7 | 21.1 70.0 290 17 9 10.5 5.8
8250 21.2 70.2 290 10 5 8.3 4.6 | 21.8 71.2 290 17 9 8.0 4.4
8000 21.8 71.2 295 9 5 9.5 5.2 | 22.4 72.3 290 17 9 9.1 5.0
7750 22.6 72.7 295 9 5 11.9 6.5 | 23.2 73.8 295 17 9 11.8 6.5
7500 23.4 74.1 295 9 5 10.2 5.6 | 24.0 75.2 295 17 9 10.1 5.6
7250 24.1 75.4 295 9 5 8.1 4.4 | 24.7 76.5 295 17 9 7.8 4.3
7000 24.7 76.5 300 9 4 8.8 4.8 | 25.3 77.5 295 17 9 8.5 4.6
6750 25.5 77.9 300 8 4 12.5 6.8 | 26.1 79.0 295 17 9 12.6 6.9
6500 26.5 79.7 295 9 4 11.7 6.4 | 27.0 80.6 295 16 8 11.7 6.4
6250 27.2 81.0 300 8 4 9.9 5.4 | 27.8 82.0 295 16 8 9.1 5.0
6000 28.0 82.4 300 7 4 9.7 5.3 | 28.5 83.3 295 16 8 9.3 5.1
5750 28.8 83.8 305 7 4 13.1 7.2 | 29.2 84.6 300 15 8 11.4 6.3
5500 30.1 86.2 300 7 3 25.5 14.0 | 30.3 86.5 300 14 7 18.2 10.0
________________________________________________________________________________
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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