Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
450
UXUS97 KGJT 161306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Monday, June 16, 2025
This forecast is for Monday, June 16, 2025:
If the trigger temperature of 89.2 F/31.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 2125 ft/min (10.8 m/s)
Maximum height of thermals.................. 25677 ft MSL (20838 ft AGL)
Forecast maximum temperature................... 99.0 F/37.7 C
Time of trigger temperature.................... 1115 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................. 13205 ft MSL (8366 ft AGL)
Thermal soaring outlook for Tuesday 06/17...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:47:40 / 20:42:18 MDT
Total possible sunshine........... 14 hr 54 min 39 sec (894 min 39 sec)
Altitude of sun at 13:14:59 MDT... 73.94 degrees
Upper air data from rawinsonde observation taken on 06/16/2025 at 0600 MDT
Freezing level.................. 16297 ft MSL (11458 ft AGL)
Convective condensation level... 24223 ft MSL (19384 ft AGL)
Lifted condensation level....... 24635 ft MSL (19796 ft AGL)
Lifted index.................... +0.3
K index......................... -3.5
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 -65.0 -85.0 265 47 24 6.0 3.3 85.6 186.1 28.1 M M
45000 -57.8 -72.0 270 82 42 3.4 1.8 73.3 164.0 22.5 M M
40000 -53.0 -63.4 280 90 46 8.9 4.9 57.8 136.0 13.7 M M
38000 -48.3 -54.9 285 89 46 7.6 4.1 56.1 132.9 12.9 M M
36000 -45.1 -49.2 285 69 36 3.3 1.8 52.2 126.0 10.5 M M
34000 -41.9 -43.4 270 40 21 4.7 2.6 47.6 117.6 7.4 M M
32000 -36.9 -34.4 265 49 25 8.7 4.8 46.3 115.4 6.7 M M
30000 -32.2 -26.0 275 45 23 4.0 2.2 44.9 112.8 5.8 M M
29000 -30.8 -23.4 275 41 21 4.4 2.4 42.8 109.0 4.3 M M
28000 -29.4 -20.9 265 36 18 2.5 1.4 40.9 105.6 2.8 M M
27000 -28.2 -18.8 260 32 16 6.4 3.5 38.7 101.7 1.1 M M
26000 -26.2 -15.2 250 38 20 6.9 3.8 37.6 99.7 0.2 M M
25000 -23.6 -10.5 255 37 19 8.3 4.5 37.2 98.9 -0.2 2052 10.4
24000 -21.0 -5.8 255 32 16 9.0 4.9 36.8 98.3 -0.4 1944 9.9
23000 -18.3 -0.9 260 29 15 9.0 4.9 36.6 97.9 -0.6 1833 9.3
22000 -15.6 3.9 245 24 13 9.0 4.9 36.3 97.4 -0.8 1722 8.7
21000 -12.9 8.8 240 22 12 9.2 5.1 36.0 96.8 -1.1 1611 8.2
20000 -10.6 12.9 225 24 12 8.1 4.4 35.3 95.5 -1.8 1513 7.7
19500 -9.1 15.6 220 24 12 10.9 6.0 35.3 95.6 -1.8 1454 7.4
19000 -7.6 18.3 225 24 12 9.3 5.1 35.4 95.7 -1.8 1394 7.1
18500 -5.5 22.1 230 20 10 9.6 5.3 35.3 95.5 -1.8 1308 6.6
18000 -4.2 24.4 245 18 9 7.8 4.3 35.1 95.2 -2.0 1255 6.4
17500 -3.1 26.4 245 18 9 8.1 4.4 34.8 94.6 -2.4 1206 6.1
17000 -1.7 28.9 245 20 10 9.6 5.3 34.7 94.4 -2.5 1152 5.9
16500 -0.3 31.5 245 21 11 9.5 5.2 34.6 94.4 -2.5 1094 5.6
16000 1.1 34.0 250 22 11 9.5 5.2 34.6 94.3 -2.6 1037 5.3
15500 2.5 36.5 250 23 12 9.5 5.2 34.6 94.2 -2.6 980 5.0
15000 3.9 39.0 250 22 11 9.5 5.2 34.5 94.2 -2.7 922 4.7
14500 5.4 41.7 255 19 10 9.5 5.2 34.5 94.0 -2.8 865 4.4
14000 6.8 44.2 260 16 8 9.4 5.2 34.4 93.9 -2.8 807 4.1
13500 8.2 46.8 270 17 9 8.9 4.9 34.3 93.8 -2.9 750 3.8
13000 9.5 49.1 265 19 10 8.4 4.6 34.1 93.4 -3.1 698 3.5
12500 10.7 51.3 270 18 9 8.3 4.6 33.9 93.0 -3.3 645 3.3
12000 12.0 53.6 265 18 9 8.3 4.6 33.7 92.7 -3.5 593 3.0
11500 13.2 55.8 270 20 10 8.3 4.6 33.5 92.2 -3.8 541 2.7
11000 14.5 58.1 260 19 10 8.3 4.6 33.2 91.8 -4.0 488 2.5
10500 15.7 60.3 260 19 10 8.4 4.6 33.0 91.4 -4.2 436 2.2
10250 16.3 61.3 260 19 10 8.0 4.4 32.9 91.2 -4.4 410 2.1
10000 16.9 62.4 260 19 10 7.8 4.3 32.7 90.9 -4.5 385 2.0
9750 17.5 63.5 260 16 8 7.9 4.3 32.6 90.6 -4.7 360 1.8
9500 18.1 64.6 255 13 7 7.9 4.3 32.4 90.4 -4.8 334 1.7
9250 18.7 65.7 255 11 6 7.9 4.3 32.3 90.1 -5.0 309 1.6
9000 19.3 66.7 260 8 4 7.9 4.3 32.1 89.9 -5.1 284 1.4
8750 19.9 67.8 260 8 4 7.9 4.3 32.0 89.6 -5.3 259 1.3
8500 20.5 68.9 255 9 4 8.0 4.4 31.8 89.3 -5.4 234 1.2
8250 21.1 70.0 250 9 4 8.2 4.5 31.7 89.1 -5.5 208 1.1
8000 21.7 71.1 260 8 4 8.2 4.5 31.6 88.9 -5.7 182 0.9
7750 22.3 72.1 250 7 4 8.2 4.5 31.5 88.7 -5.8 157 0.8
7500 22.9 73.2 205 6 3 8.2 4.5 31.4 88.5 -5.9 131 0.7
7250 23.5 74.3 180 8 4 8.2 4.5 31.2 88.2 -6.1 105 0.5
7000 24.1 75.4 165 11 6 8.3 4.5 31.1 88.0 -6.2 80 0.4
6750 24.8 76.6 165 13 7 9.9 5.4 31.1 87.9 -6.3 53 0.3
6500 25.4 77.7 155 14 7 4.3 2.4 31.0 87.7 -6.5 27 0.1
6250 25.2 77.4 150 15 8 -8.6 -4.7 30.0 86.1 -7.4 26 0.1
6000 24.3 75.7 145 15 8 -12.9 -7.1 28.4 83.1 -9.1 47 0.2
5750 23.3 73.9 145 16 8 -11.7 -6.4 26.7 80.1 -10.8 68 0.3
5500 22.4 72.3 140 18 9 -12.0 -6.6 25.1 77.1 -12.5 89 0.5
5250 21.4 70.5 130 16 8 -11.8 -6.5 23.4 74.2 -14.2 110 0.6
5000 20.5 68.9 125 14 7 -11.9 -6.6 21.8 71.3 -15.9 130 0.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/16/2025 at 0900 MDT | 06/16/2025 at 1200 MDT
|
CAPE... 0.0 LI... +1.6 | CAPE... +0.1 LI... +1.2
CINH... -0.1 K Index... +0.2 | CINH... -0.4 K Index... -0.1
|
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 -62.9 -81.2 265 51 26 3.1 1.7 | -63.3 -81.9 260 52 27 3.3 1.8
45000 -58.1 -72.6 270 74 38 2.9 1.6 | -58.2 -72.8 265 74 38 2.9 1.6
40000 -53.3 -63.9 280 90 47 6.8 3.7 | -53.4 -64.1 275 87 45 6.5 3.6
38000 -49.4 -56.9 280 85 44 6.6 3.6 | -49.5 -57.1 275 84 43 6.6 3.6
36000 -45.4 -49.7 280 79 41 6.6 3.6 | -45.5 -49.9 275 80 41 6.6 3.6
34000 -41.0 -41.8 275 65 34 6.5 3.5 | -41.3 -42.3 275 72 37 7.1 3.9
32000 -37.2 -35.0 270 52 27 6.4 3.5 | -37.0 -34.6 275 62 32 7.1 3.9
30000 -33.2 -27.8 270 43 22 6.6 3.6 | -33.1 -27.6 270 52 27 6.4 3.5
29000 -31.3 -24.3 270 40 20 6.6 3.6 | -31.1 -24.0 270 46 24 6.4 3.5
28000 -29.3 -20.7 265 36 18 6.3 3.4 | -29.2 -20.6 265 41 21 6.4 3.5
27000 -27.6 -17.7 265 33 17 5.9 3.2 | -26.9 -16.4 260 36 19 6.2 3.4
26000 -25.8 -14.4 260 31 16 5.9 3.2 | -25.0 -13.0 260 33 17 6.2 3.4
25000 -24.1 -11.4 260 29 15 5.5 3.0 | -23.2 -9.8 255 29 15 6.6 3.6
24000 -21.7 -7.1 255 28 15 8.6 4.7 | -20.9 -5.6 255 28 14 7.7 4.2
23000 -19.2 -2.6 250 28 15 8.6 4.7 | -18.6 -1.5 255 28 14 7.7 4.2
22000 -16.6 2.1 245 29 15 8.6 4.7 | -16.3 2.7 250 27 14 8.3 4.5
21000 -13.3 8.1 245 27 14 9.0 4.9 | -13.7 7.3 250 27 14 8.8 4.8
20000 -10.6 12.9 245 26 13 9.0 4.9 | -11.1 12.0 250 26 14 8.8 4.8
19500 -9.2 15.4 240 25 13 8.9 4.9 | -9.7 14.5 255 26 13 8.8 4.8
19000 -8.0 17.6 240 24 12 8.5 4.7 | -8.4 16.9 255 26 13 8.9 4.9
18500 -6.7 19.9 240 23 12 8.5 4.7 | -7.1 19.2 255 25 13 8.9 4.9
18000 -5.4 22.3 240 22 11 8.7 4.8 | -5.7 21.7 255 24 12 9.0 4.9
17500 -4.1 24.6 240 21 11 8.7 4.8 | -4.4 24.1 250 23 12 9.0 4.9
17000 -2.8 27.0 240 19 10 8.8 4.8 | -3.0 26.6 250 22 11 9.0 4.9
16500 -1.5 29.3 240 18 9 9.0 4.9 | -1.7 28.9 250 21 11 8.9 4.9
16000 -0.2 31.6 240 17 9 9.0 5.0 | -0.4 31.3 250 20 10 8.9 4.9
15500 1.1 34.0 240 16 8 8.9 4.9 | 1.0 33.8 250 19 10 9.2 5.0
15000 2.5 36.5 245 15 8 8.9 4.9 | 2.4 36.3 245 19 10 9.2 5.0
14500 3.8 38.8 245 14 7 9.2 5.1 | 3.7 38.7 245 18 9 9.2 5.0
14000 5.2 41.4 250 13 7 9.3 5.1 | 5.1 41.2 245 17 9 9.2 5.0
13500 6.6 43.9 255 13 7 9.2 5.1 | 6.5 43.7 245 16 8 9.2 5.0
13000 7.9 46.2 255 13 6 9.0 5.0 | 7.8 46.0 245 16 8 9.2 5.0
12500 9.3 48.7 260 12 6 9.0 5.0 | 9.2 48.6 245 15 8 9.2 5.0
12000 10.6 51.1 260 12 6 9.0 5.0 | 10.6 51.1 245 14 7 9.3 5.1
11500 12.0 53.6 260 12 6 9.0 4.9 | 12.0 53.6 245 14 7 9.3 5.1
11000 13.3 55.9 260 12 6 8.3 4.6 | 13.2 55.8 245 13 7 7.9 4.3
10500 14.5 58.1 260 12 6 6.7 3.7 | 14.4 57.9 250 13 7 11.4 6.3
10250 15.0 59.0 260 12 6 6.7 3.7 | 15.4 59.7 245 12 6 12.3 6.8
10000 15.6 60.1 255 12 6 9.0 4.9 | 16.1 61.0 245 12 6 8.3 4.6
9750 16.2 61.2 255 11 6 8.4 4.6 | 16.8 62.2 245 12 6 9.5 5.2
9500 16.8 62.2 255 11 6 8.5 4.6 | 17.5 63.5 245 11 6 8.8 4.8
9250 17.4 63.3 255 11 6 7.2 4.0 | 18.6 65.5 250 10 5 8.5 4.6
9000 17.9 64.2 250 11 6 6.3 3.4 | 19.3 66.7 250 10 5 10.4 5.7
8750 18.4 65.1 250 10 5 6.4 3.5 | 20.1 68.2 245 9 5 9.7 5.3
8500 18.9 66.0 245 9 5 6.1 3.3 | 20.7 69.3 245 9 4 7.2 4.0
8250 19.3 66.7 240 9 4 4.5 2.5 | 21.2 70.2 250 7 4 8.2 4.5
8000 20.0 68.0 235 7 4 5.9 3.2 | 22.0 71.6 250 7 4 11.1 6.1
7750 20.4 68.7 220 6 3 4.9 2.7 | 22.8 73.0 245 7 4 9.8 5.4
7500 20.7 69.3 210 6 3 3.0 1.7 | 23.4 74.1 250 6 3 7.9 4.3
7250 20.9 69.6 205 5 3 3.7 2.0 | 24.0 75.2 255 6 3 8.4 4.6
7000 21.3 70.3 195 5 3 8.6 4.7 | 24.8 76.6 255 5 3 12.3 6.8
6750 22.0 71.6 180 5 3 8.1 4.4 | 25.8 78.4 250 6 3 11.9 6.5
6500 22.4 72.3 170 5 2 5.3 2.9 | 26.5 79.7 250 5 3 9.9 5.4
6250 22.8 73.0 155 4 2 5.5 3.0 | 27.3 81.1 260 5 2 9.7 5.3
6000 23.3 73.9 145 4 2 9.1 5.0 | 28.0 82.4 260 4 2 11.4 6.3
5750 24.3 75.7 150 4 2 18.8 10.3 | 29.2 84.6 250 5 2 22.4 12.3
5500 25.6 78.1 135 4 2 10.7 5.9 | 31.6 88.9 270 4 2 44.0 24.1
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
06/16/2025 at 1500 MDT | 06/16/2025 at 1800 MDT
|
CAPE... +0.5 LI... -0.1 | CAPE... +0.3 LI... -0.3
CINH... -0.1 K Index... +0.2 | CINH... -0.1 K Index... +1.2
|
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 -63.6 -82.5 255 54 28 2.8 1.5 | -63.1 -81.6 255 57 30 2.1 1.2
45000 -59.3 -74.7 260 77 40 3.2 1.8 | -59.8 -75.6 260 81 42 2.6 1.4
40000 -53.7 -64.7 275 92 48 6.4 3.5 | -55.1 -67.2 270 92 47 7.0 3.9
38000 -49.8 -57.6 275 90 46 6.5 3.6 | -50.9 -59.6 270 89 46 7.0 3.8
36000 -45.9 -50.6 275 88 45 6.5 3.5 | -46.7 -52.1 265 86 44 7.0 3.8
34000 -41.5 -42.7 275 80 41 7.5 4.1 | -42.2 -44.0 270 79 41 7.6 4.2
32000 -37.0 -34.6 275 71 37 7.4 4.1 | -37.6 -35.7 270 72 37 7.6 4.2
30000 -33.0 -27.4 275 58 30 6.4 3.5 | -33.7 -28.7 270 57 29 6.2 3.4
29000 -31.1 -24.0 270 51 26 6.4 3.5 | -31.8 -25.2 265 49 25 6.2 3.4
28000 -29.2 -20.6 270 43 22 6.3 3.5 | -30.0 -22.0 265 40 21 6.3 3.5
27000 -27.4 -17.3 265 39 20 6.1 3.4 | -28.0 -18.4 260 36 18 7.0 3.8
26000 -25.1 -13.2 265 35 18 6.2 3.4 | -25.9 -14.6 255 32 16 7.0 3.9
25000 -23.3 -9.9 260 32 16 6.8 3.7 | -23.3 -9.9 250 27 14 7.5 4.1
24000 -20.9 -5.6 260 30 15 8.0 4.4 | -20.8 -5.4 245 26 13 8.3 4.5
23000 -18.5 -1.3 255 28 15 8.0 4.4 | -18.4 -1.1 245 24 13 8.3 4.5
22000 -16.1 3.0 255 27 14 8.6 4.7 | -15.9 3.4 240 23 12 8.9 4.9
21000 -13.4 7.9 250 25 13 9.1 5.0 | -13.1 8.4 235 23 12 9.5 5.2
20000 -10.7 12.7 250 24 12 9.1 5.0 | -10.2 13.6 235 22 11 9.5 5.2
19500 -9.3 15.3 250 23 12 9.1 5.0 | -8.8 16.2 235 22 11 9.5 5.2
19000 -7.9 17.8 250 23 12 9.4 5.2 | -7.3 18.9 235 22 11 9.6 5.3
18500 -6.5 20.3 245 22 12 9.4 5.2 | -5.9 21.4 235 22 11 9.6 5.3
18000 -5.1 22.8 245 22 11 9.4 5.2 | -4.4 24.1 240 22 11 9.6 5.3
17500 -3.7 25.3 245 21 11 9.5 5.2 | -3.0 26.6 240 21 11 9.6 5.2
17000 -2.3 27.9 245 21 11 9.5 5.2 | -1.6 29.1 240 21 11 9.6 5.2
16500 -0.9 30.4 245 21 11 9.5 5.2 | -0.1 31.8 240 21 11 9.6 5.3
16000 0.6 33.1 245 21 11 9.5 5.2 | 1.3 34.3 240 21 11 9.6 5.3
15500 2.0 35.6 245 20 10 9.5 5.2 | 2.8 37.0 240 21 11 9.7 5.3
15000 3.4 38.1 245 20 10 9.5 5.2 | 4.2 39.6 240 21 11 9.7 5.3
14500 4.9 40.8 245 20 10 9.5 5.2 | 5.7 42.3 245 21 11 9.6 5.3
14000 6.3 43.3 245 20 10 9.5 5.2 | 7.1 44.8 245 21 11 9.6 5.2
13500 7.7 45.9 245 20 10 9.5 5.2 | 8.5 47.3 245 21 11 9.5 5.2
13000 9.1 48.4 245 19 10 9.4 5.2 | 10.0 50.0 245 20 11 9.5 5.2
12500 10.5 50.9 250 19 10 9.4 5.2 | 11.4 52.5 245 20 10 9.5 5.2
12000 12.0 53.6 250 19 10 9.6 5.3 | 12.8 55.0 245 20 10 9.7 5.3
11500 13.4 56.1 250 18 9 9.6 5.3 | 14.3 57.7 250 20 10 9.9 5.4
11000 14.7 58.5 250 17 9 7.9 4.4 | 15.6 60.1 250 20 10 7.9 4.3
10500 15.8 60.4 250 17 9 12.0 6.6 | 16.8 62.2 250 19 10 11.1 6.1
10250 16.9 62.4 250 16 8 13.1 7.2 | 17.8 64.0 250 19 10 12.9 7.1
10000 17.6 63.7 250 16 8 8.4 4.6 | 18.6 65.5 250 19 10 9.3 5.1
9750 18.3 64.9 250 16 8 9.7 5.3 | 19.3 66.7 250 19 10 9.3 5.1
9500 19.1 66.4 250 15 8 9.2 5.0 | 20.0 68.0 250 19 10 9.6 5.3
9250 19.7 67.5 255 15 8 8.1 4.4 | 20.7 69.3 250 18 10 8.4 4.6
9000 20.3 68.5 255 15 8 9.4 5.2 | 21.3 70.3 250 18 9 8.8 4.8
8750 21.9 71.4 255 14 7 10.6 5.8 | 22.0 71.6 250 18 9 10.2 5.6
8500 22.7 72.9 255 14 7 9.2 5.1 | 23.5 74.3 250 17 9 9.3 5.1
8250 23.3 73.9 255 14 7 9.5 5.2 | 24.2 75.6 255 17 9 9.5 5.2
8000 24.1 75.4 255 14 7 11.1 6.1 | 24.9 76.8 255 17 9 10.4 5.7
7750 24.9 76.8 255 14 7 10.4 5.7 | 25.7 78.3 255 17 9 10.4 5.7
7500 25.7 78.3 255 14 7 8.7 4.8 | 26.4 79.5 255 16 8 8.5 4.7
7250 26.3 79.3 260 14 7 8.8 4.8 | 27.0 80.6 255 17 9 8.1 4.4
7000 27.0 80.6 260 14 7 11.2 6.2 | 27.7 81.9 255 16 8 10.6 5.8
6750 27.9 82.2 260 13 7 11.5 6.3 | 28.5 83.3 255 16 8 11.1 6.1
6500 28.7 83.7 260 13 7 10.7 5.9 | 29.4 84.9 255 15 8 10.5 5.8
6250 29.5 85.1 260 13 7 10.9 6.0 | 30.1 86.2 255 15 8 10.8 5.9
6000 30.3 86.5 260 13 6 8.9 4.9 | 30.9 87.6 255 15 8 8.0 4.4
5750 31.1 88.0 260 11 6 16.0 8.8 | 31.5 88.7 255 14 7 9.7 5.3
5500 34.1 93.4 265 11 6 80.2 44.0 | 33.4 92.1 255 12 6 56.8 31.2
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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