Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
481
UXUS97 KGJT 271307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Thursday, June 27, 2024
This forecast is for Thursday, June 27, 2024:
If the trigger temperature of 81.6 F/27.5 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1003 ft/min (5.1 m/s)
Maximum height of thermals.................. 16535 ft MSL (11696 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ 1400 MDT
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................. 11535 ft MSL (6696 ft AGL)
Thermal soaring outlook for Friday 06/28....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:50:29 / 20:44:18 MDT
Total possible sunshine........... 14 hr 53 min 48 sec (893 min 48 sec)
Altitude of sun at 13:17:24 MDT... 73.73 degrees
Upper air data from rawinsonde observation taken on 06/27/2024 at 0600 MDT
Freezing level.................. 15918 ft MSL (11079 ft AGL)
Convective condensation level... 13440 ft MSL (8601 ft AGL)
Lifted condensation level....... 14445 ft MSL (9605 ft AGL)
Lifted index.................... -4.7
K index......................... +29.9
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 -65.4 -85.7 270 51 26 1.5 0.8 83.4 182.1 28.9 M M
45000 -60.5 -76.9 235 59 30 5.4 2.9 67.3 153.1 20.9 M M
40000 -50.4 -58.7 230 67 35 7.8 4.3 60.2 140.4 17.6 M M
38000 -45.2 -49.4 230 67 35 9.4 5.2 59.2 138.6 17.4 M M
36000 -39.9 -39.8 240 67 34 7.3 4.0 57.5 135.4 16.6 M M
34000 -35.8 -32.4 255 46 24 2.7 1.5 54.9 130.8 15.2 M M
32000 -31.2 -24.2 260 41 21 8.7 4.8 53.3 127.9 14.4 M M
30000 -26.0 -14.8 240 37 19 8.6 4.7 52.4 126.3 14.0 M M
29000 -23.4 -10.1 245 37 19 9.3 5.1 51.9 125.4 13.8 M M
28000 -21.1 -6.0 245 38 20 6.9 3.8 51.1 123.9 13.4 M M
27000 -19.2 -2.6 250 40 21 5.1 2.8 49.9 121.8 12.5 M M
26000 -17.7 0.1 250 37 19 5.4 3.0 48.1 118.7 11.2 M M
25000 -16.2 2.8 250 37 19 5.6 3.1 46.5 115.8 9.9 M M
24000 -15.9 3.4 255 37 19 3.9 2.1 43.3 109.9 7.4 M M
23000 -13.8 7.2 260 31 16 4.3 2.3 42.5 108.5 6.7 M M
22000 -12.2 10.0 260 33 17 5.4 3.0 40.9 105.6 5.4 M M
21000 -10.5 13.1 255 33 17 6.9 3.8 39.4 103.0 4.2 M M
20000 -8.8 16.2 250 29 15 3.6 2.0 38.1 100.5 3.0 M M
19500 -7.8 18.0 245 28 14 7.6 4.2 37.6 99.8 2.6 M M
19000 -6.2 20.8 250 26 13 7.1 3.9 36.9 98.5 2.0 M M
18500 -5.2 22.6 255 28 15 7.1 3.9 36.5 97.7 1.6 M M
18000 -4.2 24.4 250 28 14 7.1 3.9 36.1 96.9 1.2 M M
17500 -3.1 26.4 250 28 14 7.1 3.9 35.6 96.1 0.8 M M
17000 -2.1 28.2 250 25 13 7.1 3.9 35.1 95.3 0.3 M M
16500 -1.1 30.0 255 22 11 7.1 3.9 34.7 94.4 -0.1 992 5.0
16000 -0.0 32.0 260 20 10 7.1 3.9 34.3 93.7 -0.5 947 4.8
15500 1.0 33.8 265 21 11 7.0 3.8 33.8 92.8 -1.0 901 4.6
15000 2.2 36.0 275 25 13 8.6 4.7 33.5 92.2 -1.3 852 4.3
14500 3.4 38.1 275 25 13 8.5 4.7 33.3 91.9 -1.5 799 4.1
14000 4.7 40.5 270 21 11 8.4 4.6 33.1 91.5 -1.7 747 3.8
13500 5.8 42.4 270 20 10 8.0 4.4 32.8 91.0 -2.1 699 3.6
13000 7.0 44.6 265 19 10 8.5 4.6 32.5 90.6 -2.4 648 3.3
12500 8.2 46.8 265 20 11 8.4 4.6 32.3 90.2 -2.6 596 3.0
12000 9.5 49.1 270 19 10 8.4 4.6 32.1 89.8 -2.8 544 2.8
11500 10.7 51.3 270 19 10 8.3 4.6 31.9 89.4 -3.0 492 2.5
11000 12.0 53.6 245 13 7 6.5 3.5 31.7 89.1 -3.3 439 2.2
10500 12.5 54.5 245 13 7 4.6 2.5 30.8 87.5 -4.2 410 2.1
10250 12.8 55.0 250 11 6 5.9 3.2 30.4 86.8 -4.7 393 2.0
10000 13.2 55.8 255 10 5 6.8 3.7 30.2 86.3 -4.9 371 1.9
9750 13.7 56.7 260 8 4 6.6 3.6 29.9 85.9 -5.2 349 1.8
9500 14.2 57.6 270 7 4 6.6 3.6 29.7 85.4 -5.5 328 1.7
9250 14.7 58.5 280 6 3 6.7 3.7 29.5 85.0 -5.7 306 1.6
9000 15.2 59.4 285 5 3 7.5 4.1 29.2 84.6 -6.0 284 1.4
8750 15.7 60.3 285 3 2 7.9 4.3 29.1 84.4 -6.1 260 1.3
8500 16.3 61.3 315 1 1 7.8 4.3 29.0 84.1 -6.3 235 1.2
8250 16.8 62.2 035 1 0 7.8 4.3 28.8 83.8 -6.5 211 1.1
8000 17.4 63.3 145 1 0 7.8 4.3 28.7 83.6 -6.7 187 1.0
7750 18.0 64.4 125 2 1 8.1 4.4 28.5 83.3 -6.9 163 0.8
7500 18.5 65.3 140 3 1 7.1 3.9 28.4 83.0 -7.1 139 0.7
7250 19.0 66.2 150 3 2 5.8 3.2 28.1 82.6 -7.4 119 0.6
7000 19.4 66.9 155 4 2 5.9 3.2 27.8 82.0 -7.7 99 0.5
6750 19.8 67.6 150 4 2 5.9 3.2 27.5 81.5 -8.0 79 0.4
6500 20.2 68.4 135 6 3 5.9 3.2 27.2 81.0 -8.4 58 0.3
6250 20.6 69.1 130 8 4 5.9 3.2 26.9 80.4 -8.7 38 0.2
6000 21.1 70.0 145 8 4 5.9 3.2 26.6 79.9 -9.0 18 0.1
5750 21.5 70.7 150 8 4 5.8 3.2 26.3 79.4 -9.3 M M
5500 21.7 71.1 155 9 5 -0.9 -0.5 25.9 78.5 -9.9 M M
5250 21.4 70.5 150 10 5 -4.5 -2.5 24.8 76.6 -10.9 M M
5000 21.3 70.3 145 9 5 6.5 3.6 24.1 75.3 -11.7 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/27/2024 at 0900 MDT | 06/27/2024 at 1200 MDT
|
CAPE... +215.7 LI... -1.6 | CAPE... +812.3 LI... -3.3
CINH... -109.3 K Index... +30.6 | CINH... -7.7 K Index... +32.2
|
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 -64.6 -84.3 240 46 24 3.0 1.6 | -64.0 -83.2 245 44 23 3.6 2.0
45000 -58.6 -73.5 240 67 34 5.8 3.2 | -57.7 -71.9 240 61 32 5.4 3.0
40000 -49.6 -57.3 230 79 41 7.6 4.2 | -49.2 -56.6 235 78 40 7.4 4.1
38000 -45.0 -49.0 230 75 39 7.6 4.2 | -44.8 -48.6 230 77 40 7.5 4.1
36000 -39.9 -39.8 225 71 37 6.9 3.8 | -39.7 -39.5 230 76 39 6.6 3.6
34000 -36.3 -33.3 230 58 30 5.9 3.2 | -36.9 -34.4 230 64 33 4.6 2.5
32000 -32.8 -27.0 230 44 23 6.3 3.5 | -34.1 -29.4 225 52 27 4.1 2.2
30000 -28.8 -19.8 235 38 20 6.9 3.8 | -29.9 -21.8 230 44 23 7.5 4.1
29000 -26.7 -16.1 235 35 18 6.9 3.8 | -27.7 -17.9 235 41 21 7.5 4.1
28000 -24.7 -12.5 240 33 17 7.3 4.0 | -25.4 -13.7 235 38 20 7.7 4.2
27000 -22.4 -8.3 245 33 17 7.5 4.1 | -23.1 -9.6 240 37 19 7.9 4.3
26000 -20.2 -4.4 245 32 17 7.5 4.1 | -20.8 -5.4 245 35 18 7.9 4.3
25000 -18.0 -0.4 250 32 16 7.6 4.1 | -18.4 -1.1 245 34 18 7.9 4.4
24000 -15.9 3.4 255 31 16 6.9 3.8 | -16.3 2.7 250 34 17 6.9 3.8
23000 -13.4 7.9 255 31 16 6.9 3.8 | -14.2 6.4 255 34 17 6.9 3.8
22000 -11.4 11.5 260 30 15 6.6 3.6 | -11.7 10.9 255 34 18 6.6 3.6
21000 -9.5 14.9 260 29 15 6.4 3.5 | -9.8 14.4 260 33 17 6.4 3.5
20000 -7.7 18.1 260 28 14 6.4 3.5 | -8.0 17.6 260 32 17 6.5 3.5
19500 -6.8 19.8 260 28 14 6.5 3.5 | -7.1 19.2 260 32 16 6.5 3.6
19000 -5.9 21.4 260 27 14 6.3 3.5 | -6.2 20.8 260 31 16 6.5 3.6
18500 -5.0 23.0 260 27 14 6.3 3.5 | -5.2 22.6 260 31 16 6.6 3.6
18000 -4.1 24.6 260 27 14 6.5 3.6 | -4.3 24.3 260 30 16 7.1 3.9
17500 -3.1 26.4 260 27 14 6.7 3.7 | -3.3 26.1 260 30 15 7.4 4.0
17000 -2.2 28.0 260 27 14 6.7 3.7 | -2.2 28.0 260 29 15 7.5 4.1
16500 -1.2 29.8 260 26 13 7.2 3.9 | -1.1 30.0 260 29 15 7.9 4.3
16000 -0.2 31.6 260 25 13 7.1 3.9 | -0.0 32.0 260 28 15 7.9 4.3
15500 0.9 33.6 260 25 13 7.5 4.1 | 1.1 34.0 260 28 14 7.7 4.2
15000 2.0 35.6 260 24 13 7.6 4.1 | 2.2 36.0 260 27 14 7.7 4.2
14500 3.1 37.6 260 24 12 7.6 4.2 | 3.3 37.9 255 26 13 7.8 4.3
14000 4.1 39.4 260 24 12 7.6 4.2 | 4.4 39.9 255 24 13 7.8 4.3
13500 5.2 41.4 260 23 12 7.7 4.2 | 5.5 41.9 255 23 12 7.9 4.3
13000 6.4 43.5 260 23 12 8.3 4.6 | 6.7 44.1 255 22 11 8.3 4.6
12500 7.6 45.7 260 23 12 8.3 4.6 | 7.9 46.2 250 21 11 8.3 4.5
12000 8.8 47.8 260 22 12 8.1 4.4 | 9.1 48.4 250 20 10 8.7 4.8
11500 10.0 50.0 260 22 11 8.2 4.5 | 10.4 50.7 250 19 10 8.9 4.9
11000 11.1 52.0 255 21 11 7.4 4.1 | 11.5 52.7 245 18 9 7.4 4.1
10500 12.2 54.0 255 20 10 7.6 4.2 | 12.6 54.7 245 17 9 10.5 5.8
10250 12.8 55.0 250 18 9 7.5 4.1 | 13.5 56.3 245 16 8 12.4 6.8
10000 13.3 55.9 250 17 9 7.2 3.9 | 14.3 57.7 245 15 8 9.0 4.9
9750 13.8 56.8 250 16 8 7.3 4.0 | 15.4 59.7 240 15 8 9.0 4.9
9500 14.3 57.7 245 15 8 7.0 3.9 | 15.6 60.1 240 14 7 9.6 5.2
9250 14.9 58.8 245 14 7 7.9 4.3 | 16.3 61.3 240 14 7 7.3 4.0
9000 15.4 59.7 240 12 6 7.0 3.8 | 16.8 62.2 240 12 6 7.9 4.3
8750 15.8 60.4 240 11 5 5.4 3.0 | 17.5 63.5 240 11 6 10.4 5.7
8500 16.7 62.1 230 8 4 5.3 2.9 | 18.2 64.8 240 11 6 10.2 5.6
8250 17.0 62.6 220 7 4 5.4 3.0 | 18.9 66.0 235 10 5 7.7 4.2
8000 17.4 63.3 215 6 3 6.0 3.3 | 20.2 68.4 235 8 4 11.6 6.4
7750 17.9 64.2 205 5 3 5.7 3.1 | 21.0 69.8 235 8 4 10.6 5.8
7500 18.2 64.8 195 5 3 4.4 2.4 | 21.7 71.1 235 8 4 8.1 4.5
7250 18.5 65.3 185 5 3 4.7 2.6 | 22.3 72.1 235 7 3 7.8 4.3
7000 19.0 66.2 175 5 2 8.5 4.7 | 23.0 73.4 235 6 3 11.7 6.4
6750 19.7 67.5 170 4 2 9.9 5.4 | 23.9 75.0 235 7 3 12.0 6.6
6500 20.4 68.7 165 5 2 9.1 5.0 | 24.7 76.5 235 6 3 10.4 5.7
6250 21.0 69.8 160 5 2 9.0 4.9 | 25.5 77.9 240 5 3 10.7 5.8
6000 21.7 71.1 155 5 3 9.9 5.5 | 26.2 79.2 240 5 2 8.4 4.6
5750 22.6 72.7 165 4 2 15.0 8.2 | 26.9 80.4 235 6 3 14.6 8.0
5500 24.0 75.2 155 4 2 24.8 13.6 | 29.9 85.8 245 4 2 82.2 45.1
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
06/27/2024 at 1500 MDT | 06/27/2024 at 1800 MDT
|
CAPE... +929.9 LI... -3.7 | CAPE... +876.2 LI... -2.5
CINH... -9.5 K Index... +32.5 | CINH... -41.6 K Index... +27.0
|
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 -64.4 -83.9 245 43 22 2.4 1.3 | -64.8 -84.6 245 49 25 2.3 1.3
45000 -58.6 -73.5 245 55 28 6.6 3.6 | -59.0 -74.2 245 62 32 6.3 3.5
40000 -48.7 -55.7 240 68 35 6.8 3.7 | -49.5 -57.1 235 68 35 6.6 3.6
38000 -44.7 -48.5 240 68 35 6.8 3.7 | -45.5 -49.9 235 61 31 6.6 3.6
36000 -40.1 -40.2 240 68 35 6.4 3.5 | -41.1 -42.0 235 53 27 6.9 3.8
34000 -36.7 -34.1 240 60 31 5.7 3.1 | -36.7 -34.1 235 45 23 7.3 4.0
32000 -33.2 -27.8 240 52 27 5.5 3.0 | -32.3 -26.1 235 37 19 7.1 3.9
30000 -29.3 -20.7 240 47 24 6.8 3.7 | -27.9 -18.2 240 36 18 7.5 4.1
29000 -27.3 -17.1 235 45 23 6.8 3.7 | -25.7 -14.3 240 36 18 7.5 4.1
28000 -25.2 -13.4 235 43 22 7.5 4.1 | -23.4 -10.1 245 36 19 7.1 3.9
27000 -22.9 -9.2 235 42 22 7.9 4.3 | -21.4 -6.5 245 37 19 6.9 3.8
26000 -20.6 -5.1 240 41 21 7.9 4.3 | -19.4 -2.9 245 37 19 6.9 3.8
25000 -18.2 -0.8 240 39 20 7.9 4.4 | -17.4 0.7 250 37 19 7.0 3.9
24000 -16.1 3.0 240 38 20 7.1 3.9 | -15.5 4.1 250 38 19 6.2 3.4
23000 -14.0 6.8 245 37 19 7.1 3.9 | -13.7 7.3 255 38 19 6.2 3.4
22000 -11.4 11.5 245 36 18 6.4 3.5 | -11.4 11.5 255 38 20 6.3 3.5
21000 -9.7 14.5 250 34 17 5.9 3.2 | -9.5 14.9 260 37 19 6.4 3.5
20000 -8.0 17.6 255 32 17 6.0 3.3 | -7.7 18.1 265 37 19 6.4 3.5
19500 -7.2 19.0 255 31 16 6.0 3.3 | -6.8 19.8 265 37 19 6.4 3.5
19000 -6.2 20.8 255 31 16 7.0 3.9 | -5.8 21.6 265 36 19 6.6 3.6
18500 -5.2 22.6 255 30 15 7.0 3.8 | -4.9 23.2 265 36 18 6.6 3.6
18000 -4.2 24.4 255 29 15 7.7 4.2 | -3.9 25.0 270 35 18 6.7 3.7
17500 -3.1 26.4 255 29 15 8.1 4.4 | -2.9 26.8 270 34 18 6.9 3.8
17000 -2.0 28.4 255 28 15 8.1 4.5 | -1.9 28.6 270 33 17 7.0 3.8
16500 -0.8 30.6 255 28 14 8.5 4.7 | -0.9 30.4 270 32 17 7.0 3.8
16000 0.5 32.9 255 27 14 8.5 4.7 | 0.1 32.2 270 31 16 7.0 3.8
15500 1.7 35.1 255 26 14 8.7 4.8 | 1.1 34.0 270 30 16 7.3 4.0
15000 2.9 37.2 255 26 13 8.8 4.8 | 2.2 36.0 265 29 15 7.4 4.1
14500 4.2 39.6 255 25 13 8.8 4.8 | 3.3 37.9 265 28 14 7.6 4.1
14000 5.5 41.9 255 24 12 8.9 4.9 | 4.4 39.9 265 27 14 7.9 4.3
13500 6.8 44.2 250 23 12 9.0 4.9 | 5.6 42.1 265 26 13 7.9 4.3
13000 8.1 46.6 250 23 12 9.4 5.2 | 6.8 44.2 265 25 13 8.7 4.8
12500 9.5 49.1 250 22 11 9.4 5.2 | 8.1 46.6 265 24 12 8.7 4.8
12000 10.9 51.6 250 21 11 9.1 5.0 | 9.3 48.7 265 23 12 8.0 4.4
11500 12.2 54.0 250 20 10 9.3 5.1 | 10.5 50.9 260 23 12 8.1 4.4
11000 13.5 56.3 250 19 10 7.8 4.3 | 11.6 52.9 260 22 12 7.0 3.9
10500 14.6 58.3 250 18 9 10.0 5.5 | 12.6 54.7 255 22 11 7.4 4.0
10250 15.5 59.9 250 17 9 12.0 6.6 | 13.2 55.8 260 22 11 8.7 4.8
10000 16.2 61.2 250 17 9 9.5 5.2 | 13.8 56.8 260 21 11 8.0 4.4
9750 16.9 62.4 250 16 8 9.2 5.0 | 14.3 57.7 260 21 11 7.3 4.0
9500 17.6 63.7 250 16 8 8.8 4.8 | 14.9 58.8 255 20 10 7.0 3.8
9250 18.3 64.9 250 16 8 10.8 5.9 | 15.4 59.7 255 20 10 9.0 5.0
9000 19.2 66.6 250 15 8 11.1 6.1 | 16.1 61.0 255 20 10 8.1 4.4
8750 19.9 67.8 250 15 8 9.2 5.1 | 16.5 61.7 255 20 10 5.6 3.1
8500 20.6 69.1 250 15 8 10.0 5.5 | 17.3 63.1 250 18 9 9.0 4.9
8250 21.3 70.3 250 14 7 8.7 4.8 | 18.1 64.6 250 19 10 8.5 4.7
8000 22.7 72.9 250 14 7 10.3 5.6 | 18.4 65.1 250 18 9 3.9 2.1
7750 23.4 74.1 250 13 7 10.5 5.8 | 18.7 65.7 250 16 8 3.8 2.1
7500 24.1 75.4 250 13 7 8.0 4.4 | 19.0 66.2 250 14 7 7.4 4.1
7250 24.6 76.3 250 13 7 7.3 4.0 | 19.7 67.5 250 14 7 9.4 5.2
7000 25.3 77.5 250 12 6 11.0 6.0 | 20.1 68.2 250 13 7 3.5 1.9
6750 26.2 79.2 250 12 6 11.5 6.3 | 20.2 68.4 255 10 5 2.7 1.5
6500 27.0 80.6 250 11 6 9.7 5.3 | 20.5 68.9 255 8 4 7.8 4.3
6250 27.6 81.7 250 11 5 9.0 4.9 | 21.1 70.0 250 7 4 10.7 5.9
6000 28.3 82.9 250 10 5 9.0 4.9 | 21.8 71.2 250 6 3 5.5 3.0
5750 29.0 84.2 250 10 5 13.0 7.1 | 21.9 71.4 255 4 2 2.5 1.4
5500 30.7 87.3 250 8 4 43.6 23.9 | 23.0 73.4 255 2 1 42.9 23.5
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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