Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
678
UXUS97 KGJT 281307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, June 28, 2024
This forecast is for Friday, June 28, 2024:
If the trigger temperature of 78.3 F/25.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1292 ft/min (6.6 m/s)
Maximum height of thermals.................. 17553 ft MSL (12714 ft AGL)
Forecast maximum temperature................... 92.0 F/33.8 C
Time of trigger temperature.................... 1045 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................. 14438 ft MSL (9599 ft AGL)
Thermal soaring outlook for Saturday 06/29..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:50:54 / 20:44:17 MDT
Total possible sunshine........... 14 hr 53 min 23 sec (893 min 23 sec)
Altitude of sun at 13:17:36 MDT... 73.67 degrees
Upper air data from rawinsonde observation taken on 06/28/2024 at 0600 MDT
Freezing level.................. 15044 ft MSL (10205 ft AGL)
Convective condensation level... 13068 ft MSL (8229 ft AGL)
Lifted condensation level....... 14849 ft MSL (10009 ft AGL)
Lifted index.................... -4.6
K index......................... +28.6
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 -63.0 -81.4 255 77 39 -5.0 -2.8 89.4 193.0 32.5 M M
45000 -60.8 -77.4 245 97 50 5.5 3.0 68.8 155.8 22.0 M M
40000 -50.5 -58.9 245 86 44 6.5 3.5 61.1 141.9 18.5 M M
38000 -46.8 -52.2 245 76 39 5.6 3.0 57.9 136.3 16.8 M M
36000 -43.6 -46.5 255 47 24 5.9 3.2 54.1 129.3 14.6 M M
34000 -39.2 -38.6 250 39 20 7.6 4.2 52.1 125.8 13.5 M M
32000 -34.6 -30.3 245 38 20 7.6 4.2 50.4 122.6 12.6 M M
30000 -29.4 -20.9 250 40 21 8.4 4.6 48.5 119.3 11.5 M M
29000 -26.9 -16.4 260 42 22 8.3 4.5 48.0 118.3 11.2 M M
28000 -24.7 -12.5 265 44 23 7.2 3.9 47.0 116.7 10.7 M M
27000 -22.5 -8.5 265 40 21 7.1 3.9 46.1 114.9 10.0 M M
26000 -20.2 -4.4 255 32 16 6.3 3.5 45.3 113.5 9.5 M M
25000 -18.2 -0.8 255 31 16 6.4 3.5 44.1 111.4 8.6 M M
24000 -16.2 2.8 270 36 19 5.0 2.8 43.0 109.4 7.8 M M
23000 -15.3 4.5 275 32 16 3.9 2.2 40.7 105.3 5.9 M M
22000 -14.0 6.8 275 33 17 4.3 2.4 39.0 102.2 4.3 M M
21000 -12.7 9.1 270 32 16 6.5 3.6 37.0 98.6 2.7 M M
20000 -10.5 13.1 265 37 19 7.7 4.2 36.3 97.3 2.1 M M
19500 -9.3 15.3 265 37 19 7.8 4.3 35.9 96.7 1.8 M M
19000 -8.0 17.6 265 40 20 8.3 4.5 35.8 96.4 1.7 M M
18500 -7.1 19.2 275 39 20 6.6 3.6 35.2 95.4 1.2 M M
18000 -6.2 20.8 270 40 21 6.5 3.6 34.7 94.4 0.6 M M
17500 -5.2 22.6 280 42 21 6.5 3.6 34.1 93.4 0.1 M M
17000 -4.3 24.3 285 44 22 6.6 3.6 33.6 92.4 -0.5 1054 5.4
16500 -2.6 27.3 280 45 23 10.3 5.7 33.1 91.6 -1.0 981 5.0
16000 -1.5 29.3 275 42 22 6.6 3.6 32.8 91.1 -1.3 932 4.7
15500 -0.6 30.9 275 38 20 5.5 3.0 32.2 90.0 -1.9 891 4.5
15000 0.2 32.4 275 35 18 5.1 2.8 31.5 88.8 -2.5 851 4.3
14500 1.2 34.2 275 31 16 8.4 4.6 31.0 87.8 -3.0 808 4.1
14000 2.4 36.3 270 28 14 8.0 4.4 30.8 87.4 -3.3 758 3.8
13500 3.5 38.3 270 27 14 8.0 4.4 30.5 86.9 -3.6 708 3.6
13000 4.7 40.5 265 25 13 8.0 4.4 30.2 86.4 -3.9 658 3.3
12500 5.9 42.6 260 23 12 8.0 4.4 29.9 85.9 -4.1 607 3.1
12000 7.1 44.8 260 20 10 8.0 4.4 29.7 85.4 -4.4 557 2.8
11500 8.3 46.9 255 18 9 8.0 4.4 29.4 84.9 -4.7 507 2.6
11000 9.4 48.9 245 16 8 8.0 4.4 29.1 84.4 -5.1 457 2.3
10500 10.6 51.1 240 11 5 8.1 4.4 28.8 83.8 -5.4 407 2.1
10250 11.2 52.2 225 9 5 7.8 4.3 28.6 83.6 -5.5 382 1.9
10000 11.8 53.2 205 6 3 7.5 4.1 28.5 83.3 -5.7 358 1.8
9750 12.3 54.1 195 7 3 7.7 4.2 28.3 82.9 -5.9 334 1.7
9500 12.9 55.2 180 8 4 7.1 3.9 28.1 82.6 -6.1 310 1.6
9250 13.3 55.9 180 9 4 4.6 2.5 27.8 82.1 -6.4 290 1.5
9000 13.5 56.3 190 8 4 3.3 1.8 27.4 81.2 -6.9 275 1.4
8750 13.8 56.8 190 9 4 3.7 2.0 26.9 80.4 -7.4 261 1.3
8500 14.0 57.2 185 9 5 3.7 2.0 26.4 79.5 -8.0 247 1.3
8250 14.2 57.6 180 9 5 3.5 1.9 25.9 78.7 -8.5 232 1.2
8000 14.5 58.1 175 10 5 4.1 2.3 25.5 77.8 -9.0 218 1.1
7750 14.7 58.5 170 11 6 2.0 1.1 25.0 77.0 -9.5 203 1.0
7500 14.6 58.3 150 11 6 -2.2 -1.2 24.2 75.6 -10.3 198 1.0
7250 14.4 57.9 135 13 7 -3.4 -1.9 23.2 73.8 -11.3 198 1.0
7000 14.1 57.4 120 15 8 -2.6 -1.4 22.2 72.0 -12.3 199 1.0
6750 13.9 57.0 120 16 8 -4.6 -2.5 21.3 70.3 -13.4 199 1.0
6500 13.6 56.5 120 17 9 2.6 1.4 20.3 68.5 -14.4 199 1.0
6250 14.2 57.6 130 16 8 10.0 5.5 20.2 68.3 -14.6 175 0.9
6000 14.8 58.6 135 16 8 7.5 4.1 20.1 68.1 -14.7 150 0.8
5750 15.2 59.4 140 16 8 6.7 3.7 19.9 67.8 -15.0 128 0.7
5500 15.6 60.1 145 17 9 6.3 3.4 19.6 67.3 -15.4 109 0.6
5250 16.0 60.8 150 18 9 6.7 3.7 19.4 66.9 -15.8 90 0.5
5000 16.4 61.5 150 18 9 5.8 3.2 19.1 66.4 -16.2 71 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/28/2024 at 0900 MDT | 06/28/2024 at 1200 MDT
|
CAPE... +347.1 LI... -3.7 | CAPE... +1061.6 LI... -5.1
CINH... -146.7 K Index... +29.8 | CINH... -32.8 K Index... +29.4
|
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 -62.2 -80.0 250 61 31 1.4 0.8 | -62.4 -80.3 250 64 33 1.4 0.8
45000 -58.3 -72.9 250 84 43 5.5 3.0 | -58.6 -73.5 250 85 44 5.2 2.9
40000 -49.6 -57.3 250 79 40 5.7 3.1 | -50.2 -58.4 245 78 40 5.9 3.2
38000 -46.1 -51.0 250 69 35 5.7 3.1 | -46.7 -52.1 250 71 36 5.9 3.3
36000 -42.7 -44.9 255 59 31 5.6 3.1 | -43.1 -45.6 255 64 33 5.8 3.2
34000 -38.6 -37.5 255 55 28 7.0 3.8 | -39.1 -38.4 255 58 30 6.9 3.8
32000 -34.5 -30.1 255 51 26 6.9 3.8 | -34.9 -30.8 260 53 27 6.8 3.7
30000 -30.2 -22.4 260 48 24 7.1 3.9 | -30.6 -23.1 265 48 25 7.4 4.0
29000 -28.1 -18.6 265 46 24 7.1 3.9 | -28.4 -19.1 265 46 23 7.4 4.0
28000 -26.0 -14.8 270 44 23 7.2 4.0 | -26.2 -15.2 270 43 22 7.5 4.1
27000 -23.7 -10.7 270 42 22 7.9 4.3 | -23.9 -11.0 270 41 21 7.9 4.4
26000 -21.3 -6.3 270 40 21 7.9 4.3 | -21.5 -6.7 270 39 20 8.0 4.4
25000 -18.3 -0.9 270 38 19 7.7 4.2 | -18.5 -1.3 270 37 19 7.7 4.2
24000 -16.7 1.9 270 36 18 4.9 2.7 | -16.7 1.9 265 34 18 6.0 3.3
23000 -15.3 4.5 270 34 18 5.0 2.7 | -14.9 5.2 265 32 16 6.0 3.3
22000 -13.8 7.2 270 32 17 5.2 2.9 | -13.1 8.4 265 30 15 6.0 3.3
21000 -12.1 10.2 270 31 16 6.1 3.4 | -11.5 11.3 260 29 15 5.7 3.1
20000 -10.4 13.3 270 30 15 6.2 3.4 | -9.8 14.4 260 28 14 5.8 3.2
19500 -9.5 14.9 270 29 15 6.1 3.3 | -9.0 15.8 260 27 14 5.7 3.1
19000 -8.5 16.7 275 28 15 7.7 4.2 | -8.1 17.4 260 27 14 7.2 4.0
18500 -7.4 18.7 275 28 14 7.8 4.3 | -7.1 19.2 260 28 14 7.2 4.0
18000 -6.3 20.7 275 28 14 8.0 4.4 | -6.0 21.2 260 28 14 7.4 4.1
17500 -5.1 22.8 275 28 14 8.4 4.6 | -4.9 23.2 260 28 14 7.8 4.3
17000 -3.9 25.0 275 28 14 8.4 4.6 | -3.8 25.2 260 28 14 7.7 4.3
16500 -2.7 27.1 275 28 14 8.4 4.6 | -2.6 27.3 260 28 14 8.4 4.6
16000 -1.4 29.5 270 28 14 8.4 4.6 | -1.4 29.5 260 28 14 8.4 4.6
15500 -0.2 31.6 270 28 14 8.5 4.6 | -0.1 31.8 260 28 14 8.5 4.7
15000 1.0 33.8 270 27 14 8.5 4.7 | 1.1 34.0 260 28 14 8.6 4.7
14500 2.3 36.1 265 27 14 8.6 4.7 | 2.4 36.3 260 28 14 8.6 4.7
14000 3.6 38.5 265 26 14 8.8 4.8 | 3.6 38.5 260 27 14 8.5 4.7
13500 4.9 40.8 265 26 13 8.9 4.9 | 4.9 40.8 260 27 14 8.6 4.7
13000 6.0 42.8 260 25 13 7.7 4.2 | 6.1 43.0 260 26 13 8.2 4.5
12500 7.2 45.0 260 23 12 7.9 4.4 | 7.3 45.1 255 25 13 8.3 4.6
12000 8.2 46.8 255 22 11 6.4 3.5 | 8.4 47.1 255 24 12 7.7 4.2
11500 9.1 48.4 255 21 11 6.6 3.6 | 9.5 49.1 255 22 11 7.9 4.3
11000 9.9 49.8 250 19 10 5.0 2.8 | 10.5 50.9 250 21 11 6.3 3.5
10500 10.5 50.9 245 18 9 4.4 2.4 | 11.3 52.3 245 19 10 6.5 3.6
10250 10.9 51.6 245 17 9 7.2 4.0 | 11.8 53.2 245 18 9 8.1 4.5
10000 11.4 52.5 240 16 8 7.4 4.0 | 12.4 54.3 240 17 9 7.9 4.3
9750 11.8 53.2 235 15 8 4.7 2.6 | 12.8 55.0 240 16 8 6.8 3.7
9500 12.1 53.8 230 15 7 5.2 2.9 | 13.3 55.9 240 14 7 7.2 4.0
9250 12.5 54.5 225 14 7 5.9 3.2 | 13.7 56.7 240 13 7 7.0 3.8
9000 13.0 55.4 225 13 7 5.2 2.9 | 14.2 57.6 240 12 6 7.2 3.9
8750 13.5 56.3 210 12 6 4.2 2.3 | 15.3 59.5 235 10 5 7.8 4.3
8500 13.8 56.8 200 11 6 4.2 2.3 | 15.8 60.4 235 9 5 5.7 3.1
8250 14.1 57.4 195 11 6 4.9 2.7 | 16.2 61.2 235 7 4 6.8 3.7
8000 14.5 58.1 190 11 6 5.3 2.9 | 16.8 62.2 235 6 3 10.2 5.6
7750 14.9 58.8 185 10 5 5.5 3.0 | 17.6 63.7 235 6 3 10.0 5.5
7500 15.3 59.5 175 10 5 4.0 2.2 | 18.3 64.9 230 6 3 7.6 4.1
7250 15.5 59.9 175 10 5 3.5 1.9 | 18.7 65.7 235 5 2 6.8 3.7
7000 15.9 60.6 170 10 5 7.6 4.1 | 19.4 66.9 240 4 2 11.2 6.2
6750 16.5 61.7 165 9 4 9.2 5.0 | 20.3 68.5 235 4 2 12.1 6.7
6500 17.1 62.8 160 9 4 7.8 4.3 | 21.1 70.0 235 4 2 9.8 5.4
6250 17.7 63.9 155 9 5 7.5 4.1 | 21.8 71.2 245 3 2 9.7 5.3
6000 18.3 64.9 155 10 5 8.9 4.9 | 22.5 72.5 250 3 1 8.4 4.6
5750 19.1 66.4 155 7 4 14.6 8.0 | 23.2 73.8 240 4 2 13.9 7.6
5500 20.5 68.9 150 7 4 26.1 14.3 | 25.7 78.3 260 2 1 67.8 37.2
5250 M M M M M M M | M M M M M M M
5000 M M M M M M M | M M M M M M M
06/28/2024 at 1500 MDT | 06/28/2024 at 1800 MDT
|
CAPE... +849.9 LI... -3.7 | CAPE... +188.2 LI... -2.0
CINH... -6.5 K Index... +25.4 | CINH... -8.9 K Index... +25.6
|
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 -62.6 -80.7 250 64 33 1.3 0.7 | -63.3 -81.9 255 64 33 1.1 0.6
45000 -59.0 -74.2 255 81 42 5.1 2.8 | -59.9 -75.8 260 72 37 5.1 2.8
40000 -50.8 -59.4 250 72 37 5.8 3.2 | -51.5 -60.7 265 53 27 6.6 3.6
38000 -47.3 -53.1 255 61 31 5.8 3.2 | -47.5 -53.5 270 44 23 6.6 3.6
36000 -43.8 -46.8 265 51 26 5.6 3.1 | -43.6 -46.5 280 37 19 6.6 3.6
34000 -39.3 -38.7 270 45 23 7.6 4.2 | -38.7 -37.7 285 36 18 8.2 4.5
32000 -34.8 -30.6 275 39 20 7.6 4.2 | -33.8 -28.8 290 35 18 8.2 4.5
30000 -30.2 -22.4 275 36 19 7.5 4.1 | -29.2 -20.6 285 34 17 7.6 4.2
29000 -28.0 -18.4 270 35 18 7.5 4.1 | -26.9 -16.4 285 33 17 7.6 4.2
28000 -25.7 -14.3 270 34 17 7.5 4.1 | -24.6 -12.3 280 32 16 7.3 4.0
27000 -23.5 -10.3 270 34 18 7.6 4.2 | -22.6 -8.7 275 32 16 6.8 3.7
26000 -20.6 -5.1 270 34 18 7.7 4.2 | -20.1 -4.2 275 32 16 6.8 3.7
25000 -18.3 -0.9 265 35 18 7.5 4.1 | -18.0 -0.4 270 32 16 6.6 3.6
24000 -16.3 2.7 265 34 17 6.8 3.7 | -16.2 2.8 270 31 16 6.1 3.4
23000 -14.2 6.4 265 33 17 6.8 3.7 | -14.4 6.1 270 31 16 6.2 3.4
22000 -12.2 10.0 265 32 16 6.3 3.4 | -12.6 9.3 270 30 16 6.1 3.3
21000 -10.7 12.7 265 30 15 5.1 2.8 | -10.9 12.4 270 30 15 6.0 3.3
20000 -9.2 15.4 260 28 14 5.2 2.8 | -9.2 15.4 265 29 15 6.1 3.3
19500 -8.4 16.9 255 27 14 5.0 2.8 | -8.3 17.1 265 28 15 6.0 3.3
19000 -7.6 18.3 255 27 14 6.8 3.7 | -7.3 18.9 265 28 14 8.1 4.4
18500 -6.7 19.9 255 26 13 6.7 3.7 | -6.1 21.0 265 27 14 7.9 4.4
18000 -5.7 21.7 255 26 13 7.2 4.0 | -5.0 23.0 265 26 13 8.3 4.5
17500 -4.6 23.7 255 26 13 7.9 4.3 | -3.7 25.3 265 25 13 8.6 4.7
17000 -3.4 25.9 255 26 13 7.9 4.3 | -2.5 27.5 260 24 13 8.6 4.7
16500 -2.2 28.0 255 26 13 8.7 4.7 | -1.2 29.8 260 24 12 8.9 4.9
16000 -1.0 30.2 255 26 13 8.6 4.7 | 0.1 32.2 260 23 12 8.9 4.9
15500 0.3 32.5 255 26 13 8.9 4.9 | 1.4 34.5 260 22 12 8.9 4.9
15000 1.6 34.9 255 25 13 9.0 4.9 | 2.7 36.9 260 22 11 8.9 4.9
14500 2.9 37.2 255 25 13 9.1 5.0 | 4.0 39.2 255 21 11 9.0 5.0
14000 4.2 39.6 255 25 13 9.2 5.0 | 5.4 41.7 255 21 11 9.2 5.1
13500 5.6 42.1 255 25 13 9.2 5.0 | 6.7 44.1 255 21 11 9.2 5.1
13000 6.9 44.4 255 24 13 9.4 5.1 | 8.1 46.6 255 20 10 9.3 5.1
12500 8.3 46.9 255 24 12 9.4 5.1 | 9.5 49.1 255 20 10 9.3 5.1
12000 9.7 49.5 255 24 12 9.3 5.1 | 10.9 51.6 260 20 10 9.6 5.3
11500 11.0 51.8 255 23 12 9.5 5.2 | 12.3 54.1 260 19 10 9.7 5.3
11000 12.3 54.1 255 23 12 8.0 4.4 | 13.6 56.5 260 19 10 7.9 4.3
10500 13.5 56.3 255 23 12 9.6 5.2 | 14.7 58.5 260 19 10 10.1 5.5
10250 14.3 57.7 255 22 11 12.0 6.6 | 15.6 60.1 260 18 9 12.4 6.8
10000 15.1 59.2 255 22 11 9.9 5.5 | 16.5 61.7 260 17 9 9.9 5.4
9750 15.8 60.4 255 21 11 8.7 4.8 | 17.1 62.8 260 17 9 9.1 5.0
9500 16.4 61.5 255 21 11 9.4 5.2 | 17.8 64.0 260 16 8 9.6 5.3
9250 17.1 62.8 255 20 10 7.8 4.3 | 18.5 65.3 260 16 8 8.5 4.7
9000 18.3 64.9 255 19 10 9.7 5.3 | 19.9 67.8 265 15 8 10.4 5.7
8750 18.9 66.0 255 18 9 9.9 5.4 | 20.6 69.1 265 15 8 10.4 5.7
8500 19.6 67.3 260 16 8 7.6 4.2 | 21.4 70.5 265 15 7 9.0 4.9
8250 20.0 68.0 260 17 9 8.2 4.5 | 22.0 71.6 265 15 8 9.0 5.0
8000 20.8 69.4 260 16 8 11.0 6.0 | 22.7 72.9 265 15 7 10.5 5.7
7750 21.5 70.7 260 15 8 10.5 5.8 | 23.5 74.3 265 14 7 10.4 5.7
7500 22.2 72.0 260 14 7 8.7 4.8 | 24.3 75.7 265 14 7 8.8 4.8
7250 22.8 73.0 265 15 8 8.1 4.4 | 24.9 76.8 265 14 7 8.2 4.5
7000 23.6 74.5 265 15 7 11.2 6.1 | 25.6 78.1 265 14 7 10.5 5.8
6750 24.4 75.9 265 13 7 11.9 6.5 | 26.4 79.5 265 13 7 10.9 6.0
6500 25.3 77.5 265 13 7 10.9 6.0 | 27.2 81.0 265 12 6 10.6 5.8
6250 26.1 79.0 265 13 7 11.3 6.2 | 28.0 82.4 270 13 6 10.9 6.0
6000 26.9 80.4 270 13 7 7.9 4.3 | 28.7 83.7 270 12 6 8.3 4.6
5750 27.4 81.3 265 12 6 12.9 7.1 | 29.3 84.7 270 11 6 10.4 5.7
5500 30.5 86.9 270 11 6 90.7 49.8 | 31.3 88.3 270 10 5 57.5 31.6
5250 M M M M M M M | M M M M M M M
5000 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) 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 at Walker Field in Grand
Junction, Colorado at
North Latitude: 39 deg 07 min 00.001 sec
West Longitude: 108 deg 31 min 59.998 sec
Elevation: 4839 feet (1475 meters)
and may not be representative of other areas along the Western Slope of
Colorado. 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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