Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
405
UXUS97 KGJT 301307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Tuesday, April 30, 2024
This forecast is for Tuesday, April 30, 2024:
If the trigger temperature of 63.4 F/17.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1020 ft/min (5.2 m/s)
Maximum height of thermals.................. 16522 ft MSL (11683 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 1100 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................. 13880 ft MSL (9041 ft AGL)
Thermal soaring outlook for Wednesday 05/01.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:16:00 / 20:06:32 MDT
Total possible sunshine........... 13 hr 50 min 32 sec (830 min 32 sec)
Altitude of sun at 13:11:16 MDT... 65.86 degrees
Upper air data from rawinsonde observation taken on 04/30/2024 at 0600 MDT
Freezing level.................. 11327 ft MSL (6488 ft AGL)
Convective condensation level... 13043 ft MSL (8204 ft AGL)
Lifted condensation level....... 14536 ft MSL (9697 ft AGL)
Lifted index.................... -2.4
K index......................... +10.0
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 -57.1 -70.8 240 44 23 6.1 3.4 104.5 220.2 46.5 M M
45000 -51.5 -60.7 270 68 35 2.7 1.5 89.0 192.2 40.2 M M
40000 -53.8 -64.8 255 87 45 -2.0 -1.1 62.3 144.2 25.5 M M
38000 -53.8 -64.8 260 91 47 -8.3 -4.5 53.5 128.4 20.3 M M
36000 -55.7 -68.3 265 87 45 3.9 2.1 42.1 107.7 12.9 M M
34000 -52.9 -63.2 270 88 45 4.3 2.3 36.6 97.8 9.4 M M
32000 -48.2 -54.8 260 81 42 7.9 4.3 35.1 95.2 8.6 M M
30000 -43.0 -45.4 260 83 43 9.2 5.1 34.2 93.6 8.2 M M
29000 -40.2 -40.4 265 82 42 8.8 4.9 34.0 93.2 8.1 M M
28000 -37.9 -36.2 265 81 42 7.8 4.3 33.2 91.8 7.6 M M
27000 -35.4 -31.7 265 76 39 8.2 4.5 32.6 90.7 7.2 M M
26000 -32.9 -27.2 260 77 40 8.3 4.5 32.0 89.6 6.8 M M
25000 -30.7 -23.3 265 77 39 7.0 3.8 31.1 88.0 6.2 M M
24000 -28.6 -19.5 270 73 38 6.9 3.8 30.0 86.1 5.4 M M
23000 -26.5 -15.7 270 68 35 7.2 4.0 29.1 84.4 4.7 M M
22000 -24.3 -11.7 270 64 33 7.3 4.0 28.2 82.8 4.0 M M
21000 -21.9 -7.4 270 59 30 7.2 3.9 27.6 81.6 3.5 M M
20000 -20.9 -5.6 270 52 27 6.5 3.6 25.3 77.6 1.7 M M
19500 -19.9 -3.8 265 48 25 6.8 3.7 24.7 76.5 1.2 M M
19000 -18.0 -0.4 260 47 24 8.7 4.8 24.3 75.8 0.9 M M
18500 -16.7 1.9 255 45 23 9.8 5.4 24.3 75.7 0.8 M M
18000 -15.2 4.6 250 43 22 9.7 5.3 24.3 75.7 0.8 M M
17500 -13.7 7.3 255 45 23 9.3 5.1 24.2 75.6 0.8 M M
17000 -12.7 9.1 255 47 24 6.0 3.3 23.8 74.9 0.4 M M
16500 -11.7 10.9 255 46 24 6.2 3.4 23.2 73.8 -0.1 1011 5.1
16000 -10.8 12.6 250 41 21 6.3 3.4 22.7 72.8 -0.7 969 4.9
15500 -9.9 14.2 250 38 20 6.3 3.5 22.1 71.7 -1.2 926 4.7
15000 -9.0 15.8 255 34 18 6.4 3.5 21.5 70.7 -1.8 884 4.5
14500 -8.1 17.4 260 35 18 6.5 3.6 20.9 69.7 -2.3 842 4.3
14000 -7.1 19.2 260 37 19 6.5 3.5 20.4 68.7 -2.9 799 4.1
13500 -6.1 21.0 260 37 19 9.7 5.3 20.0 68.1 -3.3 752 3.8
13000 -4.6 23.7 265 37 19 10.0 5.5 20.1 68.2 -3.3 692 3.5
12500 -3.1 26.4 260 36 18 9.6 5.3 20.1 68.2 -3.4 634 3.2
12000 -1.7 28.9 260 35 18 9.7 5.3 20.1 68.2 -3.4 577 2.9
11500 -0.4 31.3 260 32 16 8.7 4.7 20.0 67.9 -3.6 523 2.7
11000 0.7 33.3 260 29 15 6.4 3.5 19.6 67.3 -4.0 475 2.4
10500 1.7 35.1 260 28 14 7.0 3.8 19.1 66.4 -4.5 432 2.2
10250 2.2 36.0 260 25 13 7.6 4.2 18.9 66.1 -4.7 408 2.1
10000 2.8 37.0 260 22 11 8.2 4.5 18.8 65.8 -4.8 383 1.9
9750 3.4 38.1 260 21 11 8.8 4.8 18.7 65.7 -5.0 356 1.8
9500 4.1 39.4 260 19 10 8.7 4.8 18.6 65.5 -5.1 330 1.7
9250 4.7 40.5 260 16 8 8.8 4.8 18.5 65.4 -5.2 304 1.5
9000 5.3 41.5 265 13 7 6.5 3.6 18.4 65.1 -5.3 279 1.4
8750 5.6 42.1 270 13 7 4.7 2.6 18.0 64.5 -5.7 261 1.3
8500 6.0 42.8 280 13 7 5.3 2.9 17.7 63.8 -6.1 243 1.2
8250 6.4 43.5 295 15 8 4.8 2.6 17.3 63.2 -6.5 224 1.1
8000 6.7 44.1 305 18 9 6.3 3.4 17.0 62.5 -6.9 206 1.0
7750 7.3 45.1 305 17 9 8.2 4.5 16.8 62.2 -7.1 182 0.9
7500 7.9 46.2 310 16 8 8.3 4.5 16.7 62.0 -7.2 156 0.8
7250 8.5 47.3 315 16 8 8.3 4.5 16.6 61.9 -7.3 130 0.7
7000 9.1 48.4 310 14 7 8.3 4.5 16.5 61.7 -7.5 104 0.5
6750 9.7 49.5 315 14 7 8.2 4.5 16.4 61.5 -7.6 79 0.4
6500 10.4 50.7 320 12 6 8.5 4.7 16.3 61.3 -7.7 53 0.3
6250 11.0 51.8 310 11 6 7.5 4.1 16.1 61.0 -7.9 27 0.1
6000 11.4 52.5 300 11 6 5.9 3.2 15.9 60.6 -8.2 6 0.0
5750 11.8 53.2 295 11 6 7.7 4.3 15.6 60.2 -8.5 M M
5500 12.3 54.1 285 11 6 1.9 1.0 15.4 59.7 -8.8 M M
5250 11.9 53.4 280 10 5 -8.8 -4.8 14.3 57.8 -9.9 M M
5000 11.2 52.2 290 5 3 -9.0 -4.9 12.9 55.1 -11.4 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/30/2024 at 0900 MDT | 04/30/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.2 | CAPE... 0.0 LI... +4.2
CINH... -0.0 K Index... -5.3 | CINH... -0.1 K Index... -14.4
|
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 -56.8 -70.2 255 41 21 2.6 1.4 | -57.1 -70.8 255 43 22 2.7 1.5
45000 -53.2 -63.8 260 56 29 -1.3 -0.7 | -53.3 -63.9 260 54 28 -2.0 -1.1
40000 -55.5 -67.9 270 81 42 -1.5 -0.8 | -56.4 -69.5 270 76 39 -2.0 -1.1
38000 -55.4 -67.7 275 85 44 1.4 0.8 | -56.0 -68.8 270 80 41 2.7 1.5
36000 -54.6 -66.3 275 83 43 1.4 0.8 | -54.3 -65.7 275 79 41 2.7 1.5
34000 -52.7 -62.9 280 80 41 8.2 4.5 | -51.8 -61.2 275 77 40 8.2 4.5
32000 -47.6 -53.7 275 79 40 8.5 4.7 | -46.8 -52.2 275 76 39 8.3 4.6
30000 -42.5 -44.5 270 77 40 8.3 4.5 | -41.8 -43.2 270 74 38 8.2 4.5
29000 -40.1 -40.2 270 76 39 8.2 4.5 | -39.4 -38.9 270 72 37 8.2 4.5
28000 -37.6 -35.7 270 75 39 8.2 4.5 | -36.9 -34.4 270 70 36 8.2 4.5
27000 -35.1 -31.2 270 74 38 7.7 4.2 | -34.5 -30.1 270 68 35 7.2 3.9
26000 -33.0 -27.4 270 72 37 7.1 3.9 | -32.6 -26.7 265 65 34 6.6 3.6
25000 -30.8 -23.4 275 70 36 7.1 3.9 | -30.6 -23.1 265 62 32 6.6 3.6
24000 -28.7 -19.7 275 68 35 7.1 3.9 | -28.6 -19.5 265 59 30 6.6 3.6
23000 -26.1 -15.0 275 65 34 6.9 3.8 | -26.1 -15.0 270 55 28 6.7 3.7
22000 -24.0 -11.2 280 63 32 6.9 3.8 | -24.1 -11.4 270 52 27 6.7 3.7
21000 -21.9 -7.4 280 60 31 7.2 4.0 | -22.0 -7.6 270 48 25 7.7 4.2
20000 -19.8 -3.6 280 58 30 7.2 3.9 | -19.7 -3.5 270 45 23 7.6 4.2
19500 -18.7 -1.7 280 57 29 7.2 3.9 | -18.6 -1.5 275 43 22 7.6 4.2
19000 -17.6 0.3 285 55 29 7.2 4.0 | -17.4 0.7 275 41 21 7.6 4.2
18500 -16.5 2.3 285 54 28 6.6 3.6 | -16.3 2.7 275 39 20 7.4 4.1
18000 -15.6 3.9 280 53 27 6.6 3.6 | -15.2 4.6 275 38 20 7.4 4.1
17500 -14.6 5.7 280 52 27 6.4 3.5 | -14.1 6.6 275 37 19 7.3 4.0
17000 -13.7 7.3 280 50 26 6.1 3.3 | -13.0 8.6 280 36 18 7.1 3.9
16500 -12.8 9.0 275 49 25 6.1 3.4 | -11.9 10.6 280 35 18 7.2 3.9
16000 -11.9 10.6 275 47 24 5.9 3.2 | -10.9 12.4 275 34 17 6.5 3.6
15500 -11.0 12.2 275 45 23 5.9 3.2 | -9.9 14.2 275 33 17 6.6 3.6
15000 -10.1 13.8 270 43 22 6.0 3.3 | -9.0 15.8 275 31 16 5.7 3.1
14500 -9.3 15.3 270 41 21 6.0 3.3 | -8.2 17.2 275 30 15 5.6 3.1
14000 -8.4 16.9 270 39 20 6.1 3.4 | -7.3 18.9 270 28 15 5.7 3.1
13500 -7.5 18.5 270 36 18 6.2 3.4 | -6.5 20.3 270 26 14 5.7 3.1
13000 -6.6 20.1 270 33 17 6.5 3.6 | -5.7 21.7 265 24 12 5.7 3.1
12500 -5.6 21.9 270 30 15 6.8 3.7 | -4.9 23.2 265 22 11 5.7 3.2
12000 -4.6 23.7 270 27 14 6.7 3.7 | -4.1 24.6 265 19 10 6.5 3.6
11500 -3.7 25.3 270 24 12 6.5 3.5 | -3.0 26.6 265 18 9 7.7 4.3
11000 -2.8 27.0 275 21 11 6.5 3.6 | -1.9 28.6 265 16 8 7.4 4.1
10500 -1.8 28.8 280 19 10 6.5 3.5 | -0.8 30.6 265 15 7 6.1 3.3
10250 -1.3 29.7 280 18 9 7.5 4.1 | -0.3 31.5 265 14 7 10.3 5.7
10000 -0.7 30.7 280 16 8 8.7 4.8 | 0.6 33.1 265 13 7 12.2 6.7
9750 -0.1 31.8 285 15 8 8.1 4.4 | 1.3 34.3 265 13 7 8.6 4.7
9500 0.5 32.9 285 14 7 7.8 4.3 | 2.0 35.6 265 12 6 9.4 5.2
9250 1.1 34.0 290 13 7 7.8 4.3 | 2.7 36.9 265 11 6 7.7 4.2
9000 1.6 34.9 295 12 6 7.8 4.3 | 3.2 37.8 265 10 5 7.0 3.9
8750 2.2 36.0 300 11 6 8.3 4.5 | 3.8 38.8 270 10 5 9.5 5.2
8500 2.9 37.2 300 11 5 8.6 4.7 | 4.5 40.1 270 9 5 10.7 5.9
8250 3.5 38.3 305 10 5 8.0 4.4 | 5.9 42.6 275 8 4 7.9 4.3
8000 4.6 40.3 310 9 5 8.7 4.8 | 6.5 43.7 275 8 4 9.9 5.4
7750 5.3 41.5 310 8 4 10.4 5.7 | 7.4 45.3 275 8 4 12.1 6.6
7500 6.0 42.8 315 8 4 7.9 4.3 | 8.2 46.8 275 7 4 9.2 5.0
7250 6.5 43.7 315 7 4 5.1 2.8 | 8.7 47.7 280 7 4 6.2 3.4
7000 6.9 44.4 315 7 4 9.0 4.9 | 9.3 48.7 280 7 4 10.8 5.9
6750 7.7 45.9 315 6 3 11.4 6.3 | 10.3 50.5 280 7 4 13.4 7.3
6500 8.5 47.3 310 6 3 9.8 5.4 | 11.2 52.2 280 7 3 10.5 5.8
6250 9.2 48.6 310 6 3 10.0 5.5 | 11.9 53.4 285 7 3 10.3 5.6
6000 9.9 49.8 310 6 3 8.5 4.7 | 12.7 54.9 290 6 3 8.5 4.7
5750 10.6 51.1 310 5 3 11.2 6.1 | 13.4 56.1 285 6 3 14.5 8.0
5500 12.5 54.5 310 5 3 50.1 27.5 | 16.3 61.3 295 6 3 80.6 44.2
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
04/30/2024 at 1500 MDT | 04/30/2024 at 1800 MDT
|
CAPE... 0.0 LI... +3.6 | CAPE... 0.0 LI... +3.1
CINH... -0.0 K Index... -8.4 | CINH... -0.0 K Index... -6.9
|
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 -57.4 -71.3 255 47 24 1.9 1.1 | -58.2 -72.8 260 48 25 2.3 1.3
45000 -54.8 -66.6 255 59 30 -2.4 -1.3 | -55.1 -67.2 260 62 32 -3.0 -1.7
40000 -58.1 -72.6 265 74 38 -2.2 -1.2 | -59.1 -74.4 265 73 37 -2.8 -1.5
38000 -56.9 -70.4 265 76 39 4.4 2.4 | -57.6 -71.7 265 75 39 5.3 2.9
36000 -54.2 -65.6 270 76 39 4.4 2.4 | -54.4 -65.9 265 75 39 5.3 2.9
34000 -50.9 -59.6 270 76 39 8.2 4.5 | -50.6 -59.1 265 74 38 8.5 4.6
32000 -45.9 -50.6 270 73 38 8.2 4.5 | -45.5 -49.9 265 72 37 8.5 4.6
30000 -41.0 -41.8 270 71 37 8.3 4.6 | -40.5 -40.9 265 70 36 8.1 4.5
29000 -38.5 -37.3 270 70 36 8.3 4.6 | -38.1 -36.6 265 69 36 8.1 4.4
28000 -36.1 -33.0 270 69 36 8.3 4.6 | -35.7 -32.3 260 69 35 8.1 4.5
27000 -33.6 -28.5 270 68 35 7.0 3.9 | -33.3 -27.9 260 67 35 7.2 4.0
26000 -31.7 -25.1 265 65 34 6.5 3.6 | -31.2 -24.2 260 65 34 7.0 3.8
25000 -29.7 -21.5 265 62 32 6.5 3.6 | -29.1 -20.4 260 63 33 7.0 3.8
24000 -27.8 -18.0 260 60 31 6.4 3.5 | -27.0 -16.6 260 61 31 6.6 3.6
23000 -25.4 -13.7 260 56 29 6.2 3.4 | -24.8 -12.6 260 57 29 5.8 3.2
22000 -23.6 -10.5 255 52 27 6.2 3.4 | -23.1 -9.6 260 53 27 5.8 3.2
21000 -21.6 -6.9 255 49 25 7.5 4.1 | -21.2 -6.2 255 50 26 7.1 3.9
20000 -19.4 -2.9 255 45 23 7.4 4.0 | -19.1 -2.4 255 46 24 7.0 3.9
19500 -18.2 -0.8 255 43 22 7.4 4.0 | -18.0 -0.4 255 44 23 7.0 3.9
19000 -17.1 1.2 255 41 21 7.4 4.0 | -17.0 1.4 250 42 22 7.0 3.8
18500 -16.0 3.2 255 40 20 7.3 4.0 | -15.9 3.4 250 40 21 7.6 4.2
18000 -14.9 5.2 255 38 19 7.3 4.0 | -14.8 5.4 250 38 20 7.6 4.1
17500 -13.8 7.2 255 36 19 7.3 4.0 | -13.6 7.5 245 37 19 7.8 4.3
17000 -12.7 9.1 255 34 18 7.2 4.0 | -12.4 9.7 245 35 18 8.0 4.4
16500 -11.7 10.9 255 32 17 7.2 4.0 | -11.3 11.7 245 34 17 8.0 4.4
16000 -10.6 12.9 255 30 16 7.1 3.9 | -10.0 14.0 245 32 17 8.2 4.5
15500 -9.6 14.7 255 28 15 7.1 3.9 | -8.8 16.2 245 31 16 8.2 4.5
15000 -8.5 16.7 250 26 13 6.5 3.6 | -7.6 18.3 245 30 15 8.3 4.6
14500 -7.6 18.3 250 24 12 6.5 3.6 | -6.3 20.7 245 29 15 8.4 4.6
14000 -6.6 20.1 250 22 12 7.5 4.1 | -5.1 22.8 245 28 14 8.5 4.7
13500 -5.4 22.3 245 21 11 8.1 4.4 | -3.8 25.2 245 27 14 8.6 4.7
13000 -4.2 24.4 245 20 10 8.3 4.5 | -2.5 27.5 245 26 13 8.6 4.7
12500 -3.0 26.6 245 20 10 8.5 4.6 | -1.2 29.8 245 25 13 8.7 4.8
12000 -1.7 28.9 245 19 10 8.6 4.7 | 0.1 32.2 245 24 12 8.6 4.7
11500 -0.4 31.3 245 18 9 8.7 4.8 | 1.3 34.3 245 22 12 8.6 4.7
11000 0.9 33.6 245 17 9 8.2 4.5 | 2.6 36.7 245 21 11 8.2 4.5
10500 2.0 35.6 245 16 8 6.6 3.6 | 3.8 38.8 245 20 10 7.1 3.9
10250 2.5 36.5 245 15 8 10.3 5.7 | 4.3 39.7 245 20 10 9.6 5.2
10000 3.4 38.1 245 15 8 11.8 6.5 | 5.1 41.2 245 19 10 10.6 5.8
9750 4.1 39.4 245 14 7 8.5 4.7 | 5.8 42.4 245 18 9 8.3 4.5
9500 4.8 40.6 250 13 7 9.1 5.0 | 6.4 43.5 250 17 9 8.0 4.4
9250 5.4 41.7 250 13 6 7.5 4.1 | 7.0 44.6 250 16 8 9.0 5.0
9000 5.9 42.6 255 12 6 8.5 4.7 | 7.7 45.9 250 16 8 9.6 5.3
8750 6.7 44.1 255 12 6 10.7 5.8 | 8.4 47.1 250 15 8 8.7 4.8
8500 8.2 46.8 255 11 6 9.9 5.4 | 9.7 49.5 255 13 7 8.5 4.6
8250 8.9 48.0 260 11 6 9.4 5.2 | 10.3 50.5 255 13 7 8.4 4.6
8000 9.7 49.5 260 11 6 10.1 5.6 | 11.0 51.8 260 13 7 9.4 5.2
7750 10.5 50.9 260 11 6 11.0 6.0 | 11.7 53.1 260 13 6 10.2 5.6
7500 11.3 52.3 260 11 6 9.6 5.3 | 12.4 54.3 260 12 6 9.2 5.1
7250 11.9 53.4 265 11 5 8.0 4.4 | 13.1 55.6 260 12 6 8.0 4.4
7000 12.6 54.7 265 11 5 10.3 5.7 | 13.7 56.7 265 13 6 9.8 5.4
6750 13.4 56.1 265 10 5 12.1 6.6 | 14.5 58.1 265 12 6 11.4 6.3
6500 14.3 57.7 265 10 5 10.8 5.9 | 15.4 59.7 265 11 6 10.5 5.8
6250 15.1 59.2 270 10 5 11.1 6.1 | 16.1 61.0 265 11 6 10.8 5.9
6000 15.9 60.6 275 10 5 8.2 4.5 | 16.9 62.4 270 12 6 8.4 4.6
5750 16.5 61.7 270 9 5 13.2 7.2 | 17.5 63.5 265 10 5 9.1 5.0
5500 19.5 67.1 275 9 4 87.3 47.9 | 19.3 66.7 270 10 5 51.4 28.2
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
________________________________________________________________________________
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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