Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
815
UXUS97 KGJT 291307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Monday, April 29, 2024
This forecast is for Monday, April 29, 2024:
If the trigger temperature of 58.7 F/14.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 900 ft/min (4.6 m/s)
Maximum height of thermals.................. 15979 ft MSL (11140 ft AGL)
Forecast maximum temperature................... 73.0 F/23.2 C
Time of trigger temperature.................... 1030 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................. 14758 ft MSL (9919 ft AGL)
Thermal soaring outlook for Tuesday 04/30...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:17:13 / 20:05:33 MDT
Total possible sunshine........... 13 hr 48 min 21 sec (828 min 21 sec)
Altitude of sun at 13:11:23 MDT... 65.55 degrees
Upper air data from rawinsonde observation taken on 04/29/2024 at 0600 MDT
Freezing level.................. 9973 ft MSL (5134 ft AGL)
Convective condensation level... 11232 ft MSL (6393 ft AGL)
Lifted condensation level....... 14172 ft MSL (9333 ft AGL)
Lifted index.................... -0.3
K index......................... +8.1
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 -57.7 -71.9 275 32 17 -1.7 -0.9 105.5 221.9 47.1 M M
45000 -57.0 -70.6 280 38 20 1.8 1.0 80.7 177.2 35.4 M M
40000 -60.5 -76.9 305 50 26 -8.5 -4.7 52.1 125.7 19.2 M M
38000 -59.2 -74.6 305 51 26 5.7 3.1 45.2 113.3 15.1 M M
36000 -55.7 -68.3 310 52 27 7.3 4.0 41.7 107.1 13.1 M M
34000 -51.1 -60.0 310 48 24 8.6 4.7 40.0 104.1 12.2 M M
32000 -45.4 -49.7 305 45 23 7.7 4.2 38.7 101.7 11.7 M M
30000 -40.7 -41.3 295 47 24 7.6 4.2 37.3 99.1 10.8 M M
29000 -38.4 -37.1 295 48 25 7.8 4.3 36.4 97.5 10.3 M M
28000 -36.0 -32.8 290 49 25 8.1 4.4 35.8 96.4 9.9 M M
27000 -33.7 -28.7 295 40 21 6.4 3.5 34.9 94.9 9.4 M M
26000 -31.6 -24.9 295 38 20 8.2 4.5 33.9 93.1 8.7 M M
25000 -29.2 -20.6 300 32 17 7.8 4.3 33.3 92.0 8.3 M M
24000 -26.9 -16.4 300 30 15 7.9 4.3 32.5 90.5 7.8 M M
23000 -24.7 -12.5 295 28 14 7.7 4.2 31.6 88.9 7.1 M M
22000 -22.4 -8.3 285 27 14 7.8 4.3 30.9 87.6 6.6 M M
21000 -20.1 -4.2 290 24 12 7.8 4.3 30.2 86.3 6.1 M M
20000 -18.5 -1.3 280 25 13 4.8 2.6 28.6 83.6 4.9 M M
19500 -17.8 -0.0 285 29 15 4.8 2.6 27.8 82.0 4.1 M M
19000 -17.1 1.2 285 29 15 4.4 2.4 26.9 80.4 3.4 M M
18500 -16.1 3.0 285 30 15 6.4 3.5 26.3 79.4 2.9 M M
18000 -15.4 4.3 285 28 15 5.7 3.1 25.5 77.9 2.2 M M
17500 -14.0 6.8 275 26 14 7.4 4.1 24.5 76.1 1.4 M M
17000 -12.8 9.0 280 27 14 7.0 3.8 24.1 75.4 1.2 M M
16500 -11.7 10.9 275 27 14 5.3 2.9 23.7 74.6 0.8 M M
16000 -11.2 11.8 270 31 16 3.9 2.1 22.6 72.8 -0.1 896 4.6
15500 -10.6 12.9 270 33 17 4.6 2.5 21.6 71.0 -1.1 865 4.4
15000 -10.4 13.3 270 33 17 -1.8 -1.0 20.3 68.5 -2.4 845 4.3
14500 -10.8 12.6 280 25 13 -0.9 -0.5 18.4 65.0 -4.2 841 4.3
14000 -10.6 12.9 290 18 9 4.8 2.7 17.0 62.7 -5.5 820 4.2
13500 -9.5 14.9 290 17 9 9.2 5.1 16.7 62.1 -5.9 771 3.9
13000 -8.1 17.4 285 19 10 9.0 4.9 16.6 61.9 -6.0 716 3.6
12500 -6.8 19.8 285 18 10 8.9 4.9 16.5 61.6 -6.2 661 3.4
12000 -5.6 21.9 265 15 8 7.7 4.2 16.2 61.2 -6.5 610 3.1
11500 -4.3 24.3 270 14 7 9.6 5.3 16.1 60.9 -6.7 557 2.8
11000 -2.9 26.8 270 13 7 9.4 5.2 16.0 60.8 -6.8 500 2.5
10500 -1.5 29.3 270 14 7 9.4 5.2 15.9 60.7 -6.9 443 2.3
10250 -0.8 30.6 270 15 8 9.4 5.1 15.9 60.7 -6.9 415 2.1
10000 -0.1 31.8 270 15 8 9.3 5.1 15.9 60.6 -7.0 387 2.0
9750 0.6 33.1 270 13 7 8.7 4.7 15.8 60.5 -7.1 359 1.8
9500 1.2 34.2 265 12 6 8.2 4.5 15.7 60.3 -7.2 334 1.7
9250 1.8 35.2 265 11 6 8.3 4.6 15.6 60.1 -7.4 309 1.6
9000 2.4 36.3 260 9 5 8.3 4.6 15.5 59.9 -7.5 284 1.4
8750 3.0 37.4 260 8 4 8.2 4.5 15.4 59.7 -7.7 259 1.3
8500 3.5 38.3 265 6 3 8.7 4.8 15.3 59.5 -7.8 233 1.2
8250 4.2 39.6 265 5 2 10.3 5.6 15.3 59.5 -7.9 206 1.0
8000 4.9 40.8 230 6 3 7.4 4.1 15.2 59.4 -8.0 178 0.9
7750 5.3 41.5 220 7 3 4.3 2.4 14.9 58.8 -8.3 159 0.8
7500 5.6 42.1 190 6 3 4.6 2.5 14.5 58.1 -8.8 142 0.7
7250 5.9 42.6 165 9 4 4.9 2.7 14.1 57.4 -9.2 125 0.6
7000 6.2 43.2 150 12 6 3.4 1.9 13.7 56.7 -9.6 108 0.6
6750 6.3 43.3 150 13 7 -0.9 -0.5 13.0 55.5 -10.3 99 0.5
6500 6.2 43.2 145 12 6 0.8 0.4 12.2 54.0 -11.2 95 0.5
6250 6.5 43.7 135 12 6 5.9 3.3 11.8 53.2 -11.7 79 0.4
6000 7.0 44.6 120 13 7 7.6 4.2 11.6 52.8 -11.9 57 0.3
5750 7.5 45.5 115 13 7 8.2 4.5 11.4 52.6 -12.1 33 0.2
5500 8.1 46.6 115 14 7 10.4 5.7 11.4 52.4 -12.3 7 0.0
5250 8.8 47.8 120 14 7 4.1 2.3 11.3 52.3 -12.4 M M
5000 8.3 46.9 120 13 7 -16.0 -8.8 10.2 50.3 -13.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/29/2024 at 0900 MDT | 04/29/2024 at 1200 MDT
|
CAPE... +2.4 LI... +3.5 | CAPE... +31.6 LI... +2.8
CINH... -15.0 K Index... +10.7 | CINH... -3.5 K Index... +15.8
|
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 -57.7 -71.9 275 31 16 0.8 0.4 | -58.5 -73.3 270 35 18 0.3 0.2
45000 -56.7 -70.1 285 35 18 -2.7 -1.5 | -58.1 -72.6 280 43 22 -1.9 -1.0
40000 -60.5 -76.9 295 46 24 -2.6 -1.4 | -60.7 -77.3 290 50 26 -1.8 -1.0
38000 -58.8 -73.8 300 46 24 6.6 3.6 | -58.4 -73.1 290 50 26 7.2 4.0
36000 -54.8 -66.6 300 45 23 6.6 3.6 | -53.6 -64.5 285 47 24 7.2 4.0
34000 -50.0 -58.0 305 42 22 8.4 4.6 | -49.1 -56.4 285 45 23 8.0 4.4
32000 -45.0 -49.0 305 39 20 8.4 4.6 | -44.3 -47.7 280 42 22 8.0 4.4
30000 -40.0 -40.0 300 37 19 8.4 4.6 | -39.4 -38.9 280 40 21 8.3 4.6
29000 -37.5 -35.5 300 36 19 8.4 4.6 | -37.0 -34.6 280 40 21 8.3 4.6
28000 -35.0 -31.0 295 36 19 8.4 4.6 | -34.5 -30.1 280 39 20 8.3 4.6
27000 -32.5 -26.5 295 36 19 7.7 4.2 | -32.0 -25.6 280 39 20 8.2 4.5
26000 -30.3 -22.5 290 36 18 7.5 4.1 | -29.5 -21.1 280 39 20 8.2 4.5
25000 -28.1 -18.6 290 35 18 7.5 4.1 | -27.1 -16.8 280 39 20 8.2 4.5
24000 -25.8 -14.4 285 35 18 7.2 4.0 | -24.7 -12.5 280 39 20 7.5 4.1
23000 -23.8 -10.8 285 33 17 6.6 3.6 | -22.7 -8.9 280 38 20 6.5 3.6
22000 -21.9 -7.4 280 32 16 6.6 3.6 | -20.3 -4.5 285 36 19 6.5 3.6
21000 -19.6 -3.3 275 30 15 4.2 2.3 | -18.6 -1.5 280 35 18 3.7 2.0
20000 -18.3 -0.9 275 29 15 4.4 2.4 | -17.5 0.5 280 33 17 3.9 2.1
19500 -17.7 0.1 275 28 14 4.4 2.4 | -16.9 1.6 275 33 17 3.9 2.2
19000 -17.0 1.4 275 28 14 4.4 2.4 | -16.3 2.7 275 32 16 4.0 2.2
18500 -16.4 2.5 275 27 14 4.5 2.5 | -15.8 3.6 270 31 16 2.9 1.6
18000 -15.7 3.7 275 26 14 4.5 2.5 | -15.4 4.3 270 30 15 2.9 1.6
17500 -15.0 5.0 275 26 13 4.5 2.5 | -15.0 5.0 265 28 15 3.3 1.8
17000 -14.4 6.1 280 25 13 4.6 2.5 | -14.4 6.1 265 27 14 4.0 2.2
16500 -13.7 7.3 280 24 12 4.6 2.5 | -13.9 7.0 265 25 13 4.0 2.2
16000 -13.0 8.6 280 23 12 5.0 2.8 | -13.1 8.4 260 24 12 6.2 3.4
15500 -12.3 9.9 285 23 12 4.9 2.7 | -12.3 9.9 260 23 12 5.9 3.2
15000 -11.5 11.3 285 22 11 6.6 3.6 | -11.4 11.5 260 22 11 7.0 3.9
14500 -10.5 13.1 285 21 11 6.9 3.8 | -10.3 13.5 260 21 11 7.2 4.0
14000 -9.5 14.9 285 21 11 7.2 4.0 | -9.2 15.4 260 20 10 7.8 4.3
13500 -8.4 16.9 285 20 10 7.4 4.1 | -8.0 17.6 260 19 10 8.1 4.5
13000 -7.3 18.9 285 18 10 7.4 4.1 | -6.8 19.8 255 18 9 8.3 4.5
12500 -6.2 20.8 280 17 9 7.4 4.1 | -5.6 21.9 255 17 9 8.4 4.6
12000 -5.1 22.8 275 16 8 7.7 4.2 | -4.4 24.1 250 16 8 8.5 4.7
11500 -3.9 25.0 270 15 8 8.0 4.4 | -3.1 26.4 250 15 8 8.7 4.8
11000 -2.8 27.0 265 13 7 7.8 4.3 | -1.8 28.8 250 14 7 8.1 4.5
10500 -1.7 28.9 260 12 6 7.1 3.9 | -0.7 30.7 245 13 7 6.5 3.6
10250 -1.1 30.0 260 12 6 9.2 5.0 | -0.1 31.8 245 13 7 10.7 5.9
10000 -0.4 31.3 255 11 6 9.6 5.2 | 0.8 33.4 245 12 6 12.1 6.6
9750 0.2 32.4 255 10 5 7.7 4.2 | 1.5 34.7 245 11 6 8.5 4.7
9500 0.8 33.4 250 10 5 8.1 4.5 | 2.2 36.0 240 11 6 9.6 5.3
9250 1.4 34.5 250 9 5 7.9 4.3 | 2.9 37.2 240 10 5 7.9 4.3
9000 1.9 35.4 245 9 4 7.6 4.2 | 3.4 38.1 240 9 5 7.6 4.2
8750 2.5 36.5 245 8 4 7.5 4.1 | 4.1 39.4 235 8 4 9.6 5.3
8500 3.0 37.4 235 7 4 7.9 4.3 | 4.8 40.6 235 8 4 10.1 5.6
8250 3.6 38.5 230 7 3 7.1 3.9 | 5.5 41.9 230 7 4 9.3 5.1
8000 4.5 40.1 220 6 3 7.1 3.9 | 6.8 44.2 225 6 3 10.1 5.5
7750 5.1 41.2 210 5 3 8.7 4.8 | 7.7 45.9 225 6 3 11.5 6.3
7500 5.7 42.3 195 5 3 6.4 3.5 | 8.5 47.3 225 6 3 9.4 5.2
7250 6.0 42.8 190 5 3 3.8 2.1 | 9.1 48.4 225 5 3 7.4 4.0
7000 6.4 43.5 180 5 3 8.5 4.7 | 9.7 49.5 220 5 2 10.4 5.7
6750 7.2 45.0 175 5 3 11.0 6.0 | 10.6 51.1 220 5 3 12.1 6.6
6500 7.9 46.2 175 5 2 8.4 4.6 | 11.4 52.5 220 5 3 10.6 5.8
6250 8.5 47.3 165 5 2 7.8 4.3 | 12.2 54.0 220 4 2 11.0 6.0
6000 9.1 48.4 160 5 2 8.5 4.7 | 13.0 55.4 215 4 2 8.4 4.6
5750 9.8 49.6 165 4 2 13.8 7.6 | 13.6 56.5 220 4 2 13.0 7.1
5500 11.4 52.5 155 4 2 32.6 17.9 | 16.4 61.5 215 3 2 80.4 44.1
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
04/29/2024 at 1500 MDT | 04/29/2024 at 1800 MDT
|
CAPE... +27.3 LI... +1.2 | CAPE... +17.9 LI... -0.0
CINH... -2.7 K Index... +19.3 | CINH... -18.2 K Index... +20.5
|
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 -58.8 -73.8 275 38 19 0.0 0.0 | -59.0 -74.2 270 41 21 1.4 0.8
45000 -58.8 -73.8 275 50 26 -0.8 -0.5 | -57.1 -70.8 275 49 25 -1.6 -0.9
40000 -59.9 -75.8 275 54 28 -0.8 -0.4 | -59.0 -74.2 270 65 33 -1.3 -0.7
38000 -57.4 -71.3 275 55 28 7.0 3.8 | -56.9 -70.4 265 67 35 6.4 3.5
36000 -52.7 -62.9 275 55 29 7.0 3.8 | -52.6 -62.7 265 67 34 6.4 3.5
34000 -48.3 -54.9 270 55 28 8.0 4.4 | -48.6 -55.5 260 65 33 7.4 4.1
32000 -43.5 -46.3 270 54 28 7.9 4.4 | -44.1 -47.4 260 61 31 7.4 4.1
30000 -38.9 -38.0 265 53 27 7.6 4.2 | -39.6 -39.3 260 57 30 7.7 4.2
29000 -36.6 -33.9 265 52 27 7.6 4.2 | -37.3 -35.1 260 56 29 7.7 4.2
28000 -34.3 -29.7 265 52 27 7.6 4.2 | -35.1 -31.2 260 55 28 7.7 4.2
27000 -32.0 -25.6 265 51 26 7.6 4.2 | -32.8 -27.0 260 53 27 7.6 4.2
26000 -29.8 -21.6 265 50 26 7.6 4.2 | -30.5 -22.9 260 52 27 7.6 4.1
25000 -27.5 -17.5 270 48 25 7.6 4.2 | -28.2 -18.8 260 51 26 7.6 4.1
24000 -25.2 -13.4 270 47 24 7.4 4.0 | -26.0 -14.8 260 49 25 7.3 4.0
23000 -23.1 -9.6 270 45 23 7.1 3.9 | -23.9 -11.0 260 47 24 6.8 3.7
22000 -20.5 -4.9 270 41 21 7.1 3.9 | -21.4 -6.5 260 45 23 6.8 3.7
21000 -18.7 -1.7 270 38 20 3.3 1.8 | -19.6 -3.3 260 43 22 4.0 2.2
20000 -17.7 0.1 265 35 18 3.5 1.9 | -18.4 -1.1 260 40 20 4.2 2.3
19500 -17.2 1.0 265 34 17 3.6 2.0 | -17.8 -0.0 260 38 20 4.3 2.3
19000 -16.7 1.9 260 33 17 3.6 2.0 | -17.2 1.0 260 37 19 4.2 2.3
18500 -16.2 2.8 260 31 16 3.5 1.9 | -16.5 2.3 260 35 18 6.1 3.3
18000 -15.7 3.7 255 30 15 3.6 2.0 | -15.6 3.9 260 33 17 6.1 3.4
17500 -15.2 4.6 255 28 14 4.8 2.6 | -14.7 5.5 255 31 16 6.9 3.8
17000 -14.3 6.3 250 27 14 6.3 3.5 | -13.6 7.5 255 30 15 7.9 4.4
16500 -13.4 7.9 245 25 13 6.4 3.5 | -12.4 9.7 250 28 14 8.0 4.4
16000 -12.3 9.9 245 24 12 7.9 4.3 | -11.2 11.8 250 26 14 8.7 4.8
15500 -11.2 11.8 245 23 12 7.7 4.2 | -9.9 14.2 245 25 13 8.6 4.7
15000 -10.0 14.0 240 22 11 8.4 4.6 | -8.7 16.3 240 24 12 8.7 4.8
14500 -8.8 16.2 240 21 11 8.4 4.6 | -7.4 18.7 240 23 12 8.7 4.8
14000 -7.5 18.5 240 20 10 8.4 4.6 | -6.1 21.0 235 22 11 8.8 4.8
13500 -6.3 20.7 240 19 10 8.4 4.6 | -4.8 23.4 235 21 11 8.9 4.9
13000 -5.1 22.8 240 19 10 8.8 4.8 | -3.4 25.9 235 20 10 9.1 5.0
12500 -3.7 25.3 240 18 9 9.1 5.0 | -2.1 28.2 235 20 10 9.3 5.1
12000 -2.4 27.7 240 17 9 9.2 5.1 | -0.7 30.7 235 19 10 9.2 5.1
11500 -1.0 30.2 240 17 8 9.3 5.1 | 0.7 33.3 235 18 10 9.2 5.0
11000 0.4 32.7 240 16 8 8.6 4.7 | 2.1 35.8 235 18 9 8.8 4.8
10500 1.6 34.9 240 14 7 6.7 3.7 | 3.3 37.9 235 17 9 7.5 4.1
10250 2.2 36.0 240 13 7 11.0 6.0 | 3.9 39.0 235 17 9 10.0 5.5
10000 3.2 37.8 235 13 7 12.6 6.9 | 4.8 40.6 235 16 8 11.5 6.3
9750 3.9 39.0 235 13 7 8.9 4.9 | 5.5 41.9 235 16 8 9.3 5.1
9500 4.6 40.3 235 12 6 9.6 5.2 | 6.2 43.2 235 16 8 9.0 5.0
9250 5.3 41.5 235 12 6 8.5 4.6 | 6.9 44.4 235 15 8 9.5 5.2
9000 5.9 42.6 240 11 6 9.1 5.0 | 7.6 45.7 235 15 8 10.0 5.5
8750 6.7 44.1 235 11 6 10.5 5.8 | 8.3 46.9 235 15 7 9.6 5.3
8500 7.4 45.3 235 11 6 10.2 5.6 | 9.7 49.5 235 14 7 9.4 5.2
8250 8.9 48.0 235 10 5 9.7 5.3 | 10.5 50.9 235 14 7 9.7 5.3
8000 9.6 49.3 240 10 5 10.0 5.5 | 11.2 52.2 240 14 7 9.7 5.3
7750 10.4 50.7 235 10 5 10.5 5.8 | 11.9 53.4 240 13 7 9.7 5.3
7500 11.2 52.2 235 10 5 9.4 5.2 | 12.6 54.7 235 13 7 9.3 5.1
7250 11.8 53.2 235 9 5 8.1 4.4 | 13.3 55.9 240 13 7 8.5 4.6
7000 12.5 54.5 240 8 4 10.0 5.5 | 13.9 57.0 240 13 7 9.5 5.2
6750 13.3 55.9 235 9 4 11.3 6.2 | 14.7 58.5 240 12 6 10.4 5.7
6500 14.1 57.4 235 9 4 11.0 6.0 | 15.5 59.9 240 11 6 10.5 5.7
6250 14.9 58.8 235 8 4 12.0 6.6 | 16.3 61.3 240 12 6 11.6 6.3
6000 15.8 60.4 240 7 4 8.3 4.6 | 17.1 62.8 245 12 6 8.5 4.6
5750 16.3 61.3 235 8 4 11.2 6.1 | 17.6 63.7 240 10 5 7.8 4.3
5500 19.0 66.2 240 6 3 79.8 43.8 | 19.2 66.6 245 10 5 47.3 25.9
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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