Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
807
UXUS97 KGJT 031307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, May 3, 2024
This forecast is for Friday, May 3, 2024:
If the trigger temperature of 66.6 F/19.2 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 1579 ft/min (8.0 m/s)
Maximum height of thermals.................. 20915 ft MSL (16076 ft AGL)
Forecast maximum temperature................... 75.0 F/24.3 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ Between 20 mph and 30 mph
Height of the -3 thermal index................. 16472 ft MSL (11633 ft AGL)
Thermal soaring outlook for Saturday 05/04..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:12:27 / 20:09:26 MDT
Total possible sunshine........... 13 hr 57 min 0 sec (837 min 0 sec)
Altitude of sun at 13:10:57 MDT... 66.75 degrees
Upper air data from rawinsonde observation taken on 05/03/2024 at 0600 MDT
Freezing level.................. 11403 ft MSL (6564 ft AGL)
Convective condensation level... 17832 ft MSL (12993 ft AGL)
Lifted condensation level....... 18670 ft MSL (13830 ft AGL)
Lifted index.................... -0.2
K index......................... +12.9
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 -54.7 -66.5 255 39 20 -0.3 -0.2 110.4 230.7 49.3 M M
45000 -53.1 -63.6 270 45 23 0.5 0.3 87.0 188.7 38.6 M M
40000 -58.2 -72.8 255 69 36 2.5 1.4 55.9 132.6 20.9 M M
38000 -57.9 -72.2 265 78 40 -6.2 -3.4 47.5 117.5 15.9 M M
36000 -57.1 -70.8 270 76 39 3.9 2.2 40.1 104.1 11.2 M M
34000 -53.3 -63.9 270 73 38 7.2 4.0 37.1 98.8 9.4 M M
32000 -48.9 -56.0 260 68 35 7.4 4.1 35.1 95.2 8.2 M M
30000 -43.9 -47.0 260 61 31 7.5 4.1 33.0 91.4 6.8 M M
29000 -41.4 -42.5 260 58 30 8.8 4.8 32.5 90.4 6.5 M M
28000 -38.7 -37.7 260 57 29 8.8 4.9 32.1 89.9 6.3 M M
27000 -36.1 -33.0 260 56 29 9.0 5.0 31.8 89.2 6.1 M M
26000 -34.1 -29.4 260 51 26 5.5 3.0 30.5 87.0 5.2 M M
25000 -32.0 -25.6 260 54 28 7.3 4.0 29.5 85.1 4.5 M M
24000 -30.1 -22.2 270 44 23 4.8 2.6 28.3 83.0 3.6 M M
23000 -28.3 -18.9 260 44 23 6.1 3.3 26.9 80.4 2.4 M M
22000 -26.5 -15.7 265 46 24 6.1 3.4 25.6 78.0 1.3 M M
21000 -24.7 -12.5 260 40 21 5.8 3.2 24.2 75.6 0.2 M M
20000 -22.5 -8.5 255 38 19 8.3 4.6 23.4 74.1 -0.5 1494 7.6
19500 -21.3 -6.3 250 37 19 8.4 4.6 23.1 73.7 -0.8 1442 7.3
19000 -20.0 -4.0 245 40 21 8.3 4.6 22.9 73.2 -1.0 1390 7.1
18500 -18.8 -1.8 240 40 21 8.9 4.9 22.7 72.8 -1.2 1337 6.8
18000 -17.4 0.7 240 37 19 7.8 4.3 22.5 72.6 -1.3 1283 6.5
17500 -16.4 2.5 235 34 18 6.9 3.8 22.0 71.6 -1.8 1238 6.3
17000 -15.4 4.3 230 29 15 6.9 3.8 21.5 70.7 -2.3 1193 6.1
16500 -14.1 6.6 235 29 15 7.7 4.2 20.6 69.2 -3.1 1130 5.7
16000 -12.7 9.1 245 27 14 9.2 5.0 20.6 69.1 -3.1 1074 5.5
15500 -11.3 11.7 245 26 13 9.3 5.1 20.6 69.1 -3.2 1017 5.2
15000 -9.9 14.2 250 26 13 9.3 5.1 20.6 69.0 -3.3 961 4.9
14500 -8.5 16.7 250 28 14 9.3 5.1 20.5 68.9 -3.3 905 4.6
14000 -7.1 19.2 255 30 15 9.3 5.1 20.5 68.8 -3.4 848 4.3
13500 -5.7 21.7 255 28 14 9.3 5.1 20.4 68.7 -3.5 792 4.0
13000 -4.4 24.1 255 27 14 9.3 5.1 20.3 68.6 -3.6 735 3.7
12500 -3.0 26.6 255 26 14 9.3 5.1 20.2 68.4 -3.7 679 3.4
12000 -1.6 29.1 255 24 12 9.3 5.1 20.2 68.3 -3.8 623 3.2
11500 -0.2 31.6 245 23 12 9.3 5.1 20.1 68.1 -3.9 566 2.9
11000 1.2 34.2 250 23 12 9.3 5.1 20.0 67.9 -4.0 510 2.6
10500 2.6 36.7 245 20 10 9.3 5.1 19.9 67.7 -4.1 454 2.3
10250 3.3 37.9 245 22 11 9.3 5.1 19.8 67.6 -4.2 425 2.2
10000 4.0 39.2 250 25 13 9.3 5.1 19.7 67.5 -4.3 397 2.0
9750 4.7 40.5 250 25 13 9.2 5.1 19.7 67.5 -4.3 369 1.9
9500 5.3 41.5 250 24 12 9.2 5.1 19.7 67.4 -4.4 341 1.7
9250 6.0 42.8 245 23 12 9.2 5.1 19.6 67.4 -4.4 313 1.6
9000 6.7 44.1 250 25 13 9.2 5.1 19.6 67.3 -4.5 285 1.4
8750 7.4 45.3 245 25 13 9.2 5.1 19.6 67.2 -4.5 257 1.3
8500 8.1 46.6 245 25 13 9.3 5.1 19.5 67.1 -4.6 229 1.2
8250 8.8 47.8 240 23 12 9.2 5.0 19.5 67.1 -4.6 201 1.0
8000 9.5 49.1 235 20 10 9.4 5.2 19.4 67.0 -4.7 173 0.9
7750 10.0 50.0 240 18 9 0.6 0.3 19.2 66.5 -4.9 151 0.8
7500 9.8 49.6 235 15 7 0.7 0.4 18.2 64.8 -5.8 148 0.8
7250 10.3 50.5 230 11 6 8.1 4.5 18.0 64.4 -6.1 127 0.6
7000 10.8 51.4 220 9 4 6.7 3.7 17.8 64.0 -6.3 104 0.5
6750 11.3 52.3 205 8 4 7.2 4.0 17.6 63.6 -6.5 81 0.4
6500 11.9 53.4 190 10 5 6.5 3.6 17.3 63.2 -6.8 57 0.3
6250 12.4 54.3 180 13 7 8.7 4.8 17.1 62.8 -7.0 34 0.2
6000 12.9 55.2 170 16 8 1.9 1.0 17.0 62.5 -7.2 11 0.1
5750 12.6 54.7 160 17 9 -6.9 -3.8 15.9 60.6 -8.3 14 0.1
5500 12.1 53.8 145 16 8 -6.2 -3.4 14.7 58.4 -9.5 21 0.1
5250 11.6 52.9 130 16 8 -6.4 -3.5 13.5 56.2 -10.8 29 0.1
5000 11.1 52.0 115 13 7 -6.2 -3.4 12.2 54.0 -12.0 36 0.2
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/03/2024 at 0900 MDT | 05/03/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.8 | CAPE... +1.3 LI... +0.9
CINH... 0.0 K Index... +10.7 | CINH... -2.7 K Index... +12.9
|
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 -54.9 -66.8 250 32 17 0.8 0.4 | -55.1 -67.2 245 35 18 0.7 0.4
45000 -53.7 -64.7 255 40 21 0.2 0.1 | -54.2 -65.6 255 44 23 -2.1 -1.1
40000 -58.2 -72.8 260 69 35 -2.9 -1.6 | -58.4 -73.1 255 65 33 -2.8 -1.5
38000 -57.7 -71.9 260 72 37 4.3 2.4 | -57.7 -71.9 255 67 34 4.6 2.5
36000 -55.1 -67.2 260 69 36 4.3 2.4 | -54.9 -66.8 260 64 33 4.6 2.5
34000 -52.3 -62.1 265 66 34 7.1 3.9 | -51.9 -61.4 260 61 31 7.2 4.0
32000 -48.1 -54.6 265 62 32 6.9 3.8 | -47.6 -53.7 260 61 31 7.1 3.9
30000 -43.9 -47.0 265 59 30 8.0 4.4 | -43.3 -45.9 260 60 31 7.7 4.2
29000 -41.5 -42.7 265 58 30 7.9 4.4 | -41.0 -41.8 260 60 31 7.7 4.2
28000 -39.1 -38.4 260 58 30 7.9 4.4 | -38.7 -37.7 260 59 30 7.7 4.2
27000 -36.7 -34.1 260 57 29 7.9 4.3 | -35.8 -32.4 260 58 30 7.4 4.1
26000 -33.9 -29.0 260 56 29 7.5 4.1 | -33.6 -28.5 260 58 30 7.4 4.1
25000 -31.7 -25.1 260 56 29 7.5 4.1 | -31.4 -24.5 260 58 30 7.4 4.1
24000 -29.4 -20.9 255 55 29 7.1 3.9 | -29.1 -20.4 260 58 30 6.9 3.8
23000 -27.5 -17.5 255 52 27 6.6 3.6 | -27.2 -17.0 260 55 28 6.5 3.6
22000 -25.5 -13.9 255 49 25 6.6 3.6 | -25.3 -13.5 255 52 27 6.5 3.6
21000 -23.6 -10.5 255 45 23 6.3 3.5 | -23.3 -9.9 255 49 25 6.2 3.4
20000 -21.7 -7.1 250 43 22 6.3 3.5 | -21.5 -6.7 250 46 24 6.2 3.4
19500 -20.8 -5.4 250 42 21 6.4 3.5 | -20.6 -5.1 250 44 23 6.2 3.4
19000 -19.8 -3.6 250 40 21 6.4 3.5 | -19.7 -3.5 245 43 22 6.2 3.4
18500 -18.9 -2.0 245 39 20 7.1 3.9 | -18.8 -1.8 245 42 22 7.0 3.8
18000 -17.8 -0.0 245 39 20 7.4 4.1 | -17.7 0.1 245 41 21 7.3 4.0
17500 -16.7 1.9 245 38 20 7.5 4.1 | -16.6 2.1 245 39 20 7.4 4.1
17000 -15.5 4.1 245 38 19 8.2 4.5 | -15.5 4.1 245 38 20 8.3 4.5
16500 -14.3 6.3 245 37 19 8.2 4.5 | -14.2 6.4 240 37 19 8.2 4.5
16000 -13.0 8.6 245 36 19 8.6 4.7 | -13.0 8.6 240 37 19 8.9 4.9
15500 -11.7 10.9 245 35 18 8.6 4.7 | -11.6 11.1 240 36 18 8.9 4.9
15000 -10.5 13.1 240 35 18 8.6 4.7 | -10.3 13.5 240 35 18 8.9 4.9
14500 -9.2 15.4 245 34 18 8.6 4.7 | -9.0 15.8 240 34 18 9.0 4.9
14000 -7.9 17.8 245 34 18 8.7 4.7 | -7.6 18.3 240 33 17 9.0 4.9
13500 -6.6 20.1 245 34 17 8.7 4.8 | -6.3 20.7 240 33 17 9.0 4.9
13000 -5.3 22.5 245 33 17 8.8 4.8 | -4.9 23.2 240 32 16 9.0 4.9
12500 -4.0 24.8 245 33 17 8.9 4.9 | -3.6 25.5 245 31 16 9.1 5.0
12000 -2.6 27.3 245 32 16 8.9 4.9 | -2.2 28.0 245 30 16 9.1 5.0
11500 -1.3 29.7 245 31 16 9.0 4.9 | -0.8 30.6 245 30 15 9.2 5.1
11000 0.1 32.2 245 30 15 8.7 4.8 | 0.6 33.1 245 29 15 8.9 4.9
10500 1.3 34.3 245 29 15 7.1 3.9 | 1.8 35.2 245 28 15 7.3 4.0
10250 1.8 35.2 245 29 15 8.8 4.8 | 2.4 36.3 245 28 14 9.4 5.1
10000 2.6 36.7 245 28 14 10.9 6.0 | 3.2 37.8 245 27 14 11.2 6.2
9750 3.4 38.1 240 27 14 9.3 5.1 | 3.9 39.0 245 27 14 9.4 5.1
9500 4.0 39.2 240 26 14 8.1 4.5 | 4.6 40.3 245 26 13 8.7 4.8
9250 4.6 40.3 240 26 13 8.3 4.6 | 5.9 42.6 250 25 13 10.1 5.5
9000 5.2 41.4 240 25 13 8.6 4.7 | 6.7 44.1 250 24 12 10.4 5.7
8750 6.5 43.7 235 22 11 8.2 4.5 | 7.4 45.3 250 23 12 9.4 5.2
8500 7.1 44.8 235 21 11 8.4 4.6 | 8.2 46.8 250 22 11 9.6 5.3
8250 7.7 45.9 235 20 10 7.9 4.4 | 8.9 48.0 250 22 11 8.8 4.8
8000 8.3 46.9 235 19 10 7.0 3.8 | 9.5 49.1 255 22 11 9.5 5.2
7750 8.8 47.8 230 17 9 6.8 3.7 | 10.3 50.5 255 21 11 10.9 6.0
7500 9.3 48.7 230 15 8 6.5 3.5 | 11.1 52.0 255 20 10 9.8 5.4
7250 9.7 49.5 225 14 7 5.1 2.8 | 11.7 53.1 255 20 10 7.8 4.3
7000 10.1 50.2 225 13 7 6.0 3.3 | 12.4 54.3 255 21 11 9.7 5.3
6750 10.6 51.1 220 12 6 7.0 3.8 | 13.2 55.8 255 19 10 11.9 6.5
6500 11.1 52.0 210 11 5 7.5 4.1 | 14.1 57.4 255 18 9 11.0 6.0
6250 11.7 53.1 205 9 5 9.0 4.9 | 14.9 58.8 260 18 10 11.7 6.4
6000 12.4 54.3 200 8 4 7.0 3.8 | 15.7 60.3 260 19 10 8.6 4.7
5750 12.9 55.2 200 7 4 9.5 5.2 | 16.4 61.5 260 17 9 13.2 7.3
5500 14.7 58.5 190 6 3 47.7 26.2 | 19.4 66.9 265 15 8 85.9 47.1
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
05/03/2024 at 1500 MDT | 05/03/2024 at 1800 MDT
|
CAPE... +47.1 LI... -0.5 | CAPE... +6.5 LI... +0.4
CINH... -3.7 K Index... +17.6 | CINH... -16.4 K Index... +20.0
|
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 -55.2 -67.4 250 36 19 0.1 0.1 | -55.6 -68.1 255 36 18 0.5 0.3
45000 -55.1 -67.2 255 46 24 -1.6 -0.9 | -54.8 -66.6 260 43 22 -1.8 -1.0
40000 -58.4 -73.1 260 62 32 -2.2 -1.2 | -58.6 -73.5 265 52 27 -2.5 -1.4
38000 -57.7 -71.9 260 63 33 4.3 2.4 | -58.0 -72.4 265 53 27 4.5 2.5
36000 -55.1 -67.2 260 60 31 4.3 2.4 | -55.2 -67.4 265 52 27 4.5 2.5
34000 -51.7 -61.1 260 58 30 7.4 4.1 | -51.6 -60.9 265 51 26 7.9 4.3
32000 -47.2 -53.0 260 58 30 7.5 4.1 | -46.8 -52.2 265 51 26 7.9 4.3
30000 -42.6 -44.7 260 58 30 7.7 4.3 | -42.2 -44.0 265 52 27 7.6 4.2
29000 -40.3 -40.5 260 58 30 7.7 4.3 | -39.9 -39.8 265 52 27 7.6 4.2
28000 -38.0 -36.4 260 57 30 7.7 4.3 | -37.6 -35.7 265 52 27 7.6 4.2
27000 -35.7 -32.3 260 57 30 7.8 4.3 | -35.3 -31.5 265 53 27 7.8 4.3
26000 -33.3 -27.9 260 57 29 7.8 4.3 | -33.0 -27.4 265 53 27 7.9 4.3
25000 -31.0 -23.8 260 57 29 7.8 4.3 | -30.6 -23.1 265 53 27 7.9 4.3
24000 -28.7 -19.7 260 56 29 7.5 4.1 | -28.3 -18.9 265 53 27 7.4 4.1
23000 -26.7 -16.1 260 54 28 6.5 3.5 | -26.4 -15.5 265 52 27 6.0 3.3
22000 -24.8 -12.6 255 52 27 6.5 3.6 | -24.6 -12.3 265 50 26 6.1 3.3
21000 -22.5 -8.5 255 49 25 5.6 3.0 | -22.4 -8.3 260 48 25 6.5 3.6
20000 -20.8 -5.4 250 45 23 5.7 3.1 | -20.5 -4.9 255 45 23 6.5 3.6
19500 -20.0 -4.0 250 43 22 5.7 3.1 | -19.5 -3.1 250 44 22 6.5 3.6
19000 -19.2 -2.6 250 41 21 5.6 3.1 | -18.6 -1.5 245 43 22 6.5 3.6
18500 -18.2 -0.8 245 39 20 7.6 4.2 | -17.5 0.5 245 41 21 7.9 4.4
18000 -17.1 1.2 245 38 20 7.7 4.2 | -16.4 2.5 245 39 20 8.0 4.4
17500 -16.0 3.2 245 37 19 7.9 4.3 | -15.2 4.6 240 38 19 7.9 4.3
17000 -14.8 5.4 245 36 19 8.2 4.5 | -14.1 6.6 240 36 19 7.8 4.3
16500 -13.6 7.5 245 35 18 8.1 4.5 | -12.9 8.8 245 35 18 7.8 4.3
16000 -12.3 9.9 245 34 18 8.9 4.9 | -11.8 10.8 245 33 17 7.7 4.2
15500 -11.0 12.2 245 34 17 8.8 4.8 | -10.6 12.9 250 32 16 7.7 4.2
15000 -9.7 14.5 250 33 17 8.9 4.9 | -9.5 14.9 250 31 16 7.6 4.2
14500 -8.4 16.9 250 33 17 9.0 4.9 | -8.4 16.9 255 29 15 7.6 4.2
14000 -7.0 19.4 250 32 17 9.2 5.0 | -7.2 19.0 260 28 15 7.9 4.3
13500 -5.7 21.7 250 31 16 9.3 5.1 | -6.1 21.0 260 27 14 8.0 4.4
13000 -4.3 24.3 250 30 16 9.3 5.1 | -4.9 23.2 265 26 13 8.3 4.5
12500 -2.9 26.8 255 30 15 9.3 5.1 | -3.6 25.5 270 24 13 8.6 4.7
12000 -1.5 29.3 255 29 15 9.3 5.1 | -2.3 27.9 275 23 12 8.5 4.7
11500 -0.1 31.8 255 29 15 9.3 5.1 | -1.1 30.0 280 22 11 8.4 4.6
11000 1.3 34.3 260 28 14 8.8 4.8 | 0.2 32.4 285 21 11 7.9 4.3
10500 2.4 36.3 260 27 14 7.1 3.9 | 1.2 34.2 290 20 10 6.2 3.4
10250 3.0 37.4 260 26 13 10.1 5.6 | 1.8 35.2 295 19 10 9.1 5.0
10000 3.9 39.0 260 26 13 11.8 6.5 | 2.6 36.7 300 18 9 10.5 5.8
9750 4.7 40.5 265 25 13 9.3 5.1 | 3.2 37.8 300 18 9 8.1 4.4
9500 5.3 41.5 265 25 13 9.2 5.0 | 3.8 38.8 305 17 9 7.5 4.1
9250 6.0 42.8 265 25 13 9.4 5.2 | 4.4 39.9 310 17 9 9.5 5.2
9000 6.7 44.1 265 24 12 10.0 5.5 | 5.2 41.4 310 17 9 10.4 5.7
8750 7.5 45.5 270 23 12 10.0 5.5 | 5.9 42.6 310 17 9 9.1 5.0
8500 8.2 46.8 270 23 12 9.9 5.4 | 6.6 43.9 315 17 8 9.6 5.3
8250 9.0 48.2 270 23 12 9.9 5.4 | 7.3 45.1 315 16 8 8.9 4.9
8000 10.4 50.7 270 23 12 10.0 5.5 | 8.5 47.3 320 16 8 9.5 5.2
7750 11.2 52.2 270 23 12 10.3 5.6 | 9.3 48.7 320 16 8 11.1 6.1
7500 12.4 54.3 275 22 11 9.6 5.3 | 10.1 50.2 320 16 8 9.1 5.0
7250 12.6 54.7 275 22 12 8.6 4.7 | 10.7 51.3 325 16 8 6.8 3.7
7000 13.3 55.9 275 23 12 9.8 5.4 | 11.2 52.2 325 16 8 9.8 5.4
6750 14.1 57.4 275 22 11 10.8 5.9 | 12.1 53.8 325 15 8 12.4 6.8
6500 14.9 58.8 275 21 11 11.0 6.0 | 13.0 55.4 325 15 8 10.4 5.7
6250 15.8 60.4 275 21 11 12.6 6.9 | 13.7 56.7 325 15 8 9.7 5.3
6000 16.6 61.9 275 21 11 8.6 4.7 | 14.4 57.9 330 15 8 8.8 4.8
5750 17.2 63.0 275 19 10 13.0 7.1 | 15.1 59.2 325 13 7 11.5 6.3
5500 20.3 68.5 280 17 9 89.9 49.3 | 16.9 62.4 330 12 6 47.1 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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