Soaring Guidance
Issued by NWS Denver/Boulder, CO
Issued by NWS Denver/Boulder, CO
738
UXUS97 KBOU 021322
SRGBOU
Soaring Forecast
National Weather Service Denver/Boulder, Colorado
0720 MDT Tuesday, July 2, 2024
This forecast is for Tuesday, July 2, 2024:
If the trigger temperature of 72.4 F/22.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 845 ft/min (4.3 m/s)
Maximum height of thermals.................. 16001 ft MSL (10662 ft AGL)
Forecast maximum temperature................... 87.0 F/31.0 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12824 ft MSL (7485 ft AGL)
Thermal soaring outlook for Wednesday 07/03.... Excellent
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....................... 25316 ft MSL (19977 ft AGL)
Wave soaring outlook for Wednesday 07/03....... Poor
Remarks...
Sunrise/Sunset.................... 05:36:07 / 20:31:18 MDT
Total possible sunshine........... 14 hr 55 min 12 sec (895 min 12 sec)
Altitude of sun at 13:03:43 MDT... 73.17 degrees
Upper air data from numerical model forecast valid on 07/02/2024 at 0600 MDT
Freezing level.................. 15219 ft MSL (9880 ft AGL)
Convective condensation level... 12568 ft MSL (7229 ft AGL)
Lifted condensation level....... 14078 ft MSL (8739 ft AGL)
Lifted index.................... -3.2
K index......................... +27.3
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 -61.0 -77.8 265 37 19 3.3 1.8 M M M M M
45000 -54.9 -66.8 260 49 25 5.5 3.0 M M M M M
40000 -46.8 -52.2 250 62 32 4.5 2.5 M M M M M
38000 -43.8 -46.8 245 64 33 4.5 2.5 M M M M M
36000 -41.0 -41.8 240 65 34 4.6 2.5 M M M M M
34000 -37.0 -34.6 235 61 32 7.0 3.8 M M M M M
32000 -32.8 -27.0 235 57 29 6.9 3.8 M M M M M
30000 -28.5 -19.3 240 53 27 7.1 3.9 48.2 118.7 13.4 M M
29000 -26.3 -15.3 245 51 26 7.1 3.9 47.2 117.0 12.8 M M
28000 -24.2 -11.6 245 50 26 7.1 3.9 46.4 115.5 12.3 M M
27000 -22.1 -7.8 250 51 26 7.0 3.9 45.2 113.4 11.5 M M
26000 -20.0 -4.0 250 52 27 7.0 3.9 44.2 111.5 10.8 M M
25000 -17.8 -0.0 250 53 27 7.1 3.9 43.2 109.8 10.2 M M
24000 -15.9 3.4 250 52 27 6.2 3.4 42.0 107.6 9.3 M M
23000 -14.1 6.6 250 51 26 6.3 3.4 40.7 105.2 8.2 M M
22000 -12.3 9.9 250 50 26 6.5 3.6 39.5 103.1 7.3 M M
21000 -10.6 12.9 255 48 24 5.3 2.9 38.0 100.4 6.0 M M
20000 -8.7 16.3 260 44 23 5.3 2.9 36.0 96.8 4.3 M M
19500 -8.0 17.6 260 43 22 5.3 2.9 35.3 95.5 3.7 M M
19000 -7.2 19.0 260 42 22 5.7 3.1 34.6 94.2 3.0 M M
18500 -6.4 20.5 265 40 21 5.8 3.2 33.9 92.9 2.4 M M
18000 -5.6 21.9 265 38 20 6.2 3.4 33.2 91.7 1.7 M M
17500 -4.6 23.7 265 36 19 7.1 3.9 32.7 90.8 1.3 M M
17000 -3.6 25.5 265 35 18 7.1 3.9 32.2 90.0 0.8 M M
16500 -2.5 27.5 265 33 17 7.3 4.0 31.8 89.2 0.4 M M
16000 -1.5 29.3 265 31 16 7.3 4.0 31.4 88.5 -0.1 839 4.3
15500 -0.5 31.1 265 29 15 7.3 4.0 31.0 87.7 -0.5 794 4.0
15000 0.5 32.9 265 27 14 7.3 4.0 30.5 87.0 -0.9 748 3.8
14500 1.6 34.9 260 25 13 7.3 4.0 30.2 86.3 -1.3 702 3.6
14000 2.6 36.7 255 23 12 7.1 3.9 29.7 85.5 -1.8 657 3.3
13500 3.6 38.5 250 22 11 7.1 3.9 29.3 84.7 -2.3 612 3.1
13000 4.5 40.1 245 20 10 6.5 3.6 28.8 83.8 -2.8 569 2.9
12500 5.5 41.9 240 19 10 6.8 3.7 28.3 82.9 -3.4 527 2.7
12000 6.3 43.3 235 18 9 4.7 2.6 27.6 81.7 -4.0 488 2.5
11500 6.9 44.4 230 16 8 4.9 2.7 26.8 80.3 -4.8 452 2.3
11000 7.7 45.9 225 14 7 5.6 3.1 26.1 79.0 -5.6 415 2.1
10500 8.5 47.3 220 11 6 6.0 3.3 25.5 77.8 -6.3 376 1.9
10250 8.9 48.0 215 9 5 3.9 2.1 25.1 77.2 -6.6 356 1.8
10000 9.2 48.6 215 9 5 4.6 2.5 24.6 76.3 -7.1 342 1.7
9750 9.6 49.3 210 8 4 7.1 3.9 24.4 75.9 -7.3 320 1.6
9500 10.1 50.2 205 7 3 7.0 3.8 24.1 75.4 -7.6 297 1.5
9250 10.6 51.1 200 5 3 4.8 2.6 23.9 75.0 -7.9 275 1.4
9000 10.9 51.6 195 5 3 4.7 2.6 23.4 74.1 -8.4 261 1.3
8750 11.3 52.3 195 4 2 7.0 3.8 23.2 73.7 -8.6 239 1.2
8500 11.8 53.2 190 3 2 6.4 3.5 22.9 73.2 -8.9 217 1.1
8250 12.3 54.1 180 3 1 5.1 2.8 22.6 72.7 -9.2 197 1.0
8000 12.6 54.7 170 2 1 4.7 2.6 22.2 72.0 -9.7 180 0.9
7750 13.0 55.4 165 2 1 6.5 3.5 21.9 71.4 -10.0 160 0.8
7500 13.5 56.3 160 2 1 6.0 3.3 21.7 71.0 -10.3 139 0.7
7250 13.8 56.8 150 1 1 4.3 2.4 21.3 70.3 -10.7 120 0.6
7000 14.1 57.4 130 1 1 3.8 2.1 20.9 69.5 -11.2 105 0.5
6750 14.4 57.9 120 1 1 5.3 2.9 20.4 68.8 -11.6 88 0.4
6500 14.8 58.6 125 1 1 4.8 2.6 20.1 68.2 -12.0 69 0.4
6250 15.0 59.0 110 2 1 3.5 1.9 19.7 67.4 -12.5 54 0.3
6000 15.3 59.5 100 2 1 3.7 2.0 19.2 66.6 -13.0 40 0.2
5750 15.5 59.9 090 3 1 4.4 2.4 18.8 65.8 -13.5 25 0.1
5500 15.8 60.4 090 2 1 6.6 3.6 18.5 65.2 -14.0 8 0.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
07/02/2024 at 0900 MDT | 07/02/2024 at 1200 MDT
|
CAPE... +333.5 LI... -2.0 | CAPE... +211.2 LI... -1.3
CINH... -8.3 K Index... +24.0 | CINH... -19.4 K Index... +22.6
|
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 -60.9 -77.6 265 34 18 3.5 1.9 | -60.3 -76.5 255 29 15 3.2 1.8
45000 -54.5 -66.1 265 44 23 5.7 3.1 | -54.2 -65.6 255 39 20 5.7 3.1
40000 -45.8 -50.4 255 60 31 4.5 2.5 | -45.6 -50.1 250 60 31 4.0 2.2
38000 -43.1 -45.6 250 65 33 4.5 2.5 | -43.2 -45.8 250 65 34 4.0 2.2
36000 -40.4 -40.7 245 70 36 4.4 2.4 | -40.8 -41.4 245 70 36 3.9 2.2
34000 -37.0 -34.6 240 69 35 5.9 3.2 | -37.7 -35.9 245 67 34 5.4 3.0
32000 -33.5 -28.3 240 66 34 5.9 3.2 | -34.4 -29.9 245 61 32 5.5 3.0
30000 -29.5 -21.1 240 61 31 7.0 3.9 | -30.3 -22.5 250 57 29 7.4 4.1
29000 -26.9 -16.4 245 57 30 7.0 3.9 | -27.5 -17.5 255 55 28 7.4 4.1
28000 -24.8 -12.6 245 55 28 7.7 4.2 | -25.3 -13.5 260 53 27 8.1 4.4
27000 -22.4 -8.3 250 55 28 8.1 4.4 | -22.8 -9.0 260 54 28 8.5 4.7
26000 -20.0 -4.0 250 56 29 8.1 4.4 | -20.2 -4.4 260 55 28 8.5 4.7
25000 -17.6 0.3 250 56 29 8.5 4.6 | -17.7 0.1 260 55 28 8.7 4.8
24000 -15.8 3.6 250 55 28 5.0 2.7 | -15.6 3.9 260 55 28 6.6 3.6
23000 -14.4 6.1 250 53 27 5.1 2.8 | -13.6 7.5 265 54 28 6.7 3.7
22000 -12.9 8.8 250 51 26 5.2 2.9 | -11.6 11.1 265 54 28 6.8 3.8
21000 -11.3 11.7 250 49 25 5.5 3.0 | -10.3 13.5 265 52 27 3.6 2.0
20000 -9.7 14.5 255 48 25 5.6 3.1 | -9.3 15.3 260 50 26 3.8 2.1
19500 -8.9 16.0 255 47 24 5.6 3.1 | -8.7 16.3 260 49 25 3.9 2.1
19000 -8.1 17.4 260 46 24 6.0 3.3 | -8.2 17.2 260 48 25 4.6 2.5
18500 -7.2 19.0 260 46 23 6.1 3.4 | -7.5 18.5 260 47 24 4.9 2.7
18000 -6.3 20.7 265 45 23 6.1 3.4 | -6.8 19.8 260 46 24 4.9 2.7
17500 -5.4 22.3 265 44 23 6.6 3.6 | -6.1 21.0 260 45 23 5.6 3.1
17000 -4.4 24.1 265 42 22 6.6 3.6 | -5.3 22.5 260 44 23 5.5 3.0
16500 -3.5 25.7 265 40 21 7.0 3.9 | -4.5 23.9 265 43 22 6.5 3.6
16000 -2.5 27.5 265 38 20 7.2 4.0 | -3.5 25.7 265 42 22 7.0 3.8
15500 -0.9 30.4 265 35 18 7.3 4.0 | -2.0 28.4 265 40 20 7.6 4.2
15000 0.1 32.2 265 33 17 7.3 4.0 | -0.9 30.4 265 38 19 7.7 4.2
14500 1.2 34.2 265 31 16 7.3 4.0 | 0.1 32.2 265 36 18 7.7 4.2
14000 2.2 36.0 265 30 15 7.2 4.0 | 1.2 34.2 270 34 17 7.7 4.2
13500 3.2 37.8 265 28 14 7.1 3.9 | 2.3 36.1 270 31 16 7.5 4.1
13000 4.2 39.6 265 25 13 6.6 3.6 | 3.4 38.1 270 28 15 7.2 4.0
12500 5.1 41.2 260 23 12 6.6 3.6 | 4.4 39.9 270 25 13 7.3 4.0
12000 5.9 42.6 260 20 11 5.7 3.1 | 5.4 41.7 275 23 12 7.2 4.0
11500 6.7 44.1 255 17 9 5.8 3.2 | 6.5 43.7 280 20 11 7.2 4.0
11000 7.5 45.5 255 14 7 5.3 2.9 | 7.5 45.5 280 18 9 6.8 3.7
10500 8.3 46.9 250 11 6 4.6 2.5 | 8.5 47.3 285 15 8 4.5 2.4
10250 8.5 47.3 250 10 5 3.7 2.0 | 8.7 47.7 290 14 7 5.6 3.1
10000 8.9 48.0 245 9 5 6.0 3.3 | 9.4 48.9 290 13 7 10.1 5.6
9750 9.4 48.9 245 8 4 7.3 4.0 | 10.1 50.2 290 12 6 9.7 5.3
9500 9.9 49.8 240 6 3 6.8 3.7 | 10.8 51.4 295 11 6 9.1 5.0
9250 10.3 50.5 235 4 2 4.7 2.6 | 11.3 52.3 295 10 5 6.4 3.5
9000 10.6 51.1 230 4 2 4.8 2.6 | 11.8 53.2 300 9 5 8.1 4.5
8750 11.0 51.8 230 2 1 6.6 3.6 | 12.5 54.5 300 8 4 10.8 5.9
8500 11.5 52.7 245 1 1 5.8 3.2 | 13.2 55.8 305 7 4 9.6 5.3
8250 11.9 53.4 000 0 0 4.5 2.5 | 13.8 56.8 310 6 3 7.8 4.3
8000 12.2 54.0 085 1 0 5.1 2.8 | 14.4 57.9 315 6 3 8.9 4.9
7750 12.6 54.7 070 1 1 7.3 4.0 | 15.2 59.4 315 6 3 11.9 6.5
7500 13.2 55.8 040 1 1 6.8 3.7 | 16.0 60.8 315 5 3 10.1 5.6
7250 13.6 56.5 050 2 1 5.5 3.0 | 16.7 62.1 315 5 3 7.7 4.2
7000 14.0 57.2 065 2 1 6.0 3.3 | 17.3 63.1 320 5 3 8.9 4.9
6750 14.5 58.1 065 2 1 10.5 5.7 | 18.1 64.6 320 5 3 13.0 7.1
6500 15.3 59.5 040 1 1 10.7 5.9 | 19.1 66.4 320 4 2 12.0 6.6
6250 15.9 60.6 050 1 1 8.4 4.6 | 19.8 67.6 325 4 2 9.7 5.3
6000 16.5 61.7 055 1 1 8.4 4.6 | 20.6 69.1 330 4 2 9.1 5.0
5750 17.2 63.0 055 1 1 13.0 7.1 | 21.3 70.3 330 4 2 15.3 8.4
5500 18.5 65.3 040 1 1 23.0 12.6 | 23.0 73.4 330 4 2 31.0 17.0
07/02/2024 at 1500 MDT | 07/02/2024 at 1800 MDT
|
CAPE... +134.2 LI... -0.6 | CAPE... +149.2 LI... +0.4
CINH... -40.6 K Index... +22.8 | CINH... -27.7 K Index... +21.5
|
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 -59.9 -75.8 245 29 15 2.8 1.6 | -59.7 -75.5 240 33 17 3.3 1.8
45000 -54.3 -65.7 240 41 21 5.7 3.1 | -53.6 -64.5 240 47 24 5.5 3.0
40000 -45.6 -50.1 250 61 32 4.1 2.3 | -45.3 -49.5 250 63 32 3.5 1.9
38000 -43.1 -45.6 250 66 34 4.1 2.3 | -43.3 -45.9 250 67 34 3.4 1.9
36000 -40.7 -41.3 250 71 37 4.1 2.2 | -41.2 -42.2 255 71 36 3.4 1.9
34000 -38.0 -36.4 250 68 35 4.5 2.5 | -38.8 -37.8 255 68 35 4.3 2.3
32000 -35.3 -31.5 250 62 32 4.6 2.5 | -36.2 -33.2 260 64 33 4.3 2.4
30000 -31.0 -23.8 255 56 29 7.1 3.9 | -31.9 -25.4 260 59 31 7.1 3.9
29000 -28.9 -20.0 260 54 28 7.1 3.9 | -29.8 -21.6 260 57 29 7.1 3.9
28000 -26.7 -16.1 265 52 27 8.4 4.6 | -27.7 -17.9 265 55 28 8.3 4.6
27000 -24.0 -11.2 265 51 26 9.1 5.0 | -25.0 -13.0 265 53 27 8.9 4.9
26000 -21.2 -6.2 265 50 26 9.2 5.0 | -22.3 -8.1 265 52 27 8.9 4.9
25000 -18.5 -1.3 265 49 25 9.3 5.1 | -19.7 -3.5 265 50 26 8.9 4.9
24000 -16.3 2.7 270 48 25 6.9 3.8 | -17.5 0.5 270 48 24 7.0 3.8
23000 -14.2 6.4 270 48 25 6.9 3.8 | -15.4 4.3 270 45 23 7.0 3.8
22000 -12.2 10.0 270 47 24 6.9 3.8 | -13.3 8.1 270 42 21 6.8 3.7
21000 -10.8 12.6 270 45 23 4.1 2.2 | -11.6 11.1 270 37 19 5.4 3.0
20000 -9.6 14.7 270 42 22 4.2 2.3 | -10.1 13.8 270 32 17 5.5 3.0
19500 -9.0 15.8 270 41 21 4.2 2.3 | -9.3 15.3 270 30 15 5.5 3.0
19000 -8.4 16.9 270 40 20 5.0 2.7 | -8.5 16.7 270 28 14 5.9 3.3
18500 -7.7 18.1 265 38 20 5.2 2.9 | -7.6 18.3 270 27 14 6.0 3.3
18000 -6.9 19.6 265 37 19 5.3 2.9 | -6.8 19.8 270 25 13 6.2 3.4
17500 -6.1 21.0 265 35 18 6.2 3.4 | -5.8 21.6 270 24 12 6.9 3.8
17000 -5.2 22.6 265 33 17 6.1 3.4 | -4.9 23.2 270 23 12 6.9 3.8
16500 -3.8 25.2 265 31 16 7.9 4.3 | -3.8 25.2 270 21 11 8.4 4.6
16000 -2.7 27.1 265 30 15 7.8 4.3 | -2.0 28.4 270 19 10 8.5 4.6
15500 -1.5 29.3 270 28 14 8.4 4.6 | -0.7 30.7 270 18 9 9.0 5.0
15000 -0.3 31.5 270 26 14 8.4 4.6 | 0.6 33.1 275 17 9 9.0 4.9
14500 0.9 33.6 270 25 13 8.2 4.5 | 1.9 35.4 275 15 8 8.9 4.9
14000 2.0 35.6 270 22 11 8.1 4.5 | 3.3 37.9 280 14 7 8.9 4.9
13500 3.2 37.8 270 20 10 8.2 4.5 | 4.6 40.3 280 13 7 8.9 4.9
13000 4.4 39.9 275 17 9 8.4 4.6 | 5.9 42.6 285 12 6 9.0 4.9
12500 5.6 42.1 275 15 8 8.5 4.7 | 7.2 45.0 290 11 6 9.0 4.9
12000 6.9 44.4 275 13 7 9.0 5.0 | 8.5 47.3 290 10 5 8.9 4.9
11500 8.2 46.8 280 11 6 9.0 5.0 | 9.9 49.8 295 9 5 8.8 4.8
11000 9.6 49.3 280 10 5 9.3 5.1 | 11.2 52.2 300 8 4 8.4 4.6
10500 11.0 51.8 285 9 5 5.0 2.7 | 12.4 54.3 310 7 4 4.4 2.4
10250 11.2 52.2 285 9 5 6.2 3.4 | 12.6 54.7 310 8 4 5.9 3.2
10000 12.1 53.8 285 9 5 12.9 7.1 | 13.4 56.1 315 7 4 12.4 6.8
9750 12.9 55.2 285 8 4 11.3 6.2 | 14.2 57.6 315 7 4 11.0 6.1
9500 13.8 56.8 290 8 4 10.8 5.9 | 15.1 59.2 320 7 3 9.8 5.4
9250 14.5 58.1 290 8 4 8.3 4.6 | 15.7 60.3 325 7 4 7.5 4.1
9000 15.1 59.2 290 8 4 9.5 5.2 | 16.3 61.3 325 7 4 9.7 5.3
8750 15.9 60.6 295 7 4 11.2 6.1 | 17.1 62.8 325 6 3 11.5 6.3
8500 16.7 62.1 295 7 4 10.2 5.6 | 17.9 64.2 330 6 3 10.1 5.5
8250 17.4 63.3 295 7 3 8.5 4.6 | 18.6 65.5 330 6 3 7.8 4.3
8000 18.0 64.4 300 7 3 9.4 5.2 | 19.2 66.6 335 6 3 9.2 5.0
7750 18.8 65.8 300 6 3 11.6 6.4 | 20.0 68.0 335 6 3 11.8 6.5
7500 19.6 67.3 300 6 3 9.9 5.4 | 20.8 69.4 335 5 3 9.6 5.3
7250 20.3 68.5 300 6 3 7.7 4.2 | 21.4 70.5 335 5 3 7.2 4.0
7000 20.9 69.6 305 6 3 8.8 4.8 | 22.0 71.6 340 6 3 8.7 4.8
6750 21.7 71.1 305 5 3 12.6 6.9 | 22.7 72.9 340 5 3 12.2 6.7
6500 22.6 72.7 305 5 2 11.9 6.5 | 23.7 74.7 340 4 2 11.3 6.2
6250 23.4 74.1 310 5 2 10.0 5.5 | 24.4 75.9 340 5 2 9.2 5.0
6000 24.2 75.6 315 5 2 9.5 5.2 | 25.1 77.2 340 5 2 9.4 5.1
5750 24.9 76.8 315 4 2 14.4 7.9 | 25.9 78.6 345 5 2 12.8 7.0
5500 26.5 79.7 315 4 2 28.9 15.9 | 27.1 80.8 345 4 2 20.7 11.3
________________________________________________________________________________
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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