Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
151
UXUS97 KGJT 251306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Wednesday, June 25, 2025
This forecast is for Wednesday, June 25, 2025:
If the trigger temperature of 80.3 F/26.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1861 ft/min (9.5 m/s)
Maximum height of thermals.................. 21777 ft MSL (16938 ft AGL)
Forecast maximum temperature................... 90.0 F/32.7 C
Time of trigger temperature.................... 1000 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................. 14157 ft MSL (9317 ft AGL)
Thermal soaring outlook for Thursday 06/26..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:49:39 / 20:44:12 MDT
Total possible sunshine........... 14 hr 54 min 33 sec (894 min 33 sec)
Altitude of sun at 13:16:56 MDT... 73.84 degrees
Upper air data from rawinsonde observation taken on 06/25/2025 at 0600 MDT
Freezing level.................. 14577 ft MSL (9738 ft AGL)
Convective condensation level... 17097 ft MSL (12258 ft AGL)
Lifted condensation level....... 17963 ft MSL (13124 ft AGL)
Lifted index.................... -2.6
K index......................... +25.5
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 -59.7 -75.5 220 46 23 2.8 1.6 96.4 205.6 37.1 M M
45000 -60.1 -76.2 200 99 51 -1.3 -0.7 70.3 158.5 23.6 M M
40000 -51.2 -60.2 210 95 49 6.6 3.6 61.3 142.4 19.3 M M
38000 -48.7 -55.7 205 98 51 2.4 1.3 56.4 133.5 16.5 M M
36000 -44.5 -48.1 195 86 44 7.6 4.1 53.9 129.1 15.2 M M
34000 -41.7 -43.1 205 85 44 7.2 4.0 49.7 121.5 12.5 M M
32000 -37.1 -34.8 205 80 41 6.3 3.5 46.9 116.4 10.8 M M
30000 -33.3 -27.9 205 68 35 7.9 4.3 44.1 111.5 9.0 M M
29000 -30.9 -23.6 200 68 35 7.9 4.3 43.5 110.2 8.6 M M
28000 -29.0 -20.2 205 62 32 4.4 2.4 42.2 108.0 7.7 M M
27000 -27.6 -17.7 210 53 27 4.3 2.3 40.3 104.5 6.3 M M
26000 -25.5 -13.9 215 47 24 8.1 4.5 39.2 102.6 5.5 M M
25000 -23.2 -9.8 210 39 20 6.9 3.8 38.5 101.2 5.0 M M
24000 -21.7 -7.1 205 36 19 5.7 3.1 36.7 98.1 3.6 M M
23000 -20.0 -4.0 200 32 16 5.8 3.2 35.2 95.4 2.4 M M
22000 -18.3 -0.9 210 31 16 0.2 0.1 33.7 92.6 1.2 M M
21000 -18.3 -0.9 200 25 13 10.4 5.7 30.5 86.9 -1.7 1626 8.3
20000 -15.3 4.5 200 25 13 10.1 5.5 30.6 87.1 -1.7 1507 7.7
19500 -13.8 7.2 200 21 11 10.1 5.5 30.6 87.1 -1.6 1448 7.4
19000 -12.3 9.9 200 22 11 9.7 5.3 30.7 87.2 -1.6 1388 7.1
18500 -10.9 12.4 195 25 13 9.6 5.2 30.6 87.1 -1.7 1330 6.8
18000 -9.4 15.1 190 23 12 9.0 4.9 30.6 87.1 -1.7 1272 6.5
17500 -8.0 17.6 200 23 12 10.5 5.7 30.6 87.0 -1.8 1216 6.2
17000 -5.9 21.4 195 22 11 8.2 4.5 30.6 87.0 -1.8 1129 5.7
16500 -4.7 23.5 205 18 9 8.2 4.5 30.3 86.6 -2.1 1079 5.5
16000 -3.5 25.7 195 15 8 8.8 4.8 30.1 86.2 -2.4 1029 5.2
15500 -2.2 28.0 200 13 7 8.9 4.9 30.0 85.9 -2.6 975 5.0
15000 -0.9 30.4 195 13 6 8.9 4.9 29.8 85.7 -2.7 921 4.7
14500 0.4 32.7 215 14 7 8.9 4.9 29.7 85.4 -2.9 867 4.4
14000 1.7 35.1 210 18 9 9.3 5.1 29.6 85.2 -3.1 812 4.1
13500 3.1 37.6 210 17 9 9.3 5.1 29.5 85.1 -3.2 757 3.8
13000 4.4 39.9 220 21 11 9.0 4.9 29.4 84.9 -3.3 702 3.6
12500 5.8 42.4 220 21 11 8.9 4.9 29.3 84.7 -3.4 647 3.3
12000 7.0 44.6 215 21 11 8.4 4.6 29.1 84.3 -3.7 596 3.0
11500 8.1 46.6 215 21 11 8.8 4.8 28.9 84.0 -4.0 546 2.8
11000 9.4 48.9 210 19 10 8.9 4.9 28.7 83.7 -4.2 493 2.5
10500 10.6 51.1 225 14 7 7.4 4.1 28.5 83.3 -4.5 442 2.2
10250 11.2 52.2 230 13 7 8.2 4.5 28.3 83.0 -4.6 417 2.1
10000 11.9 53.4 230 13 7 8.4 4.6 28.2 82.8 -4.7 390 2.0
9750 12.5 54.5 225 11 6 8.3 4.6 28.1 82.6 -4.8 364 1.8
9500 13.1 55.6 220 9 5 8.4 4.6 28.0 82.4 -4.9 337 1.7
9250 13.8 56.8 210 8 4 8.4 4.6 27.9 82.3 -5.0 311 1.6
9000 14.4 57.9 210 6 3 8.4 4.6 27.8 82.1 -5.1 284 1.4
8750 15.0 59.0 230 5 2 8.4 4.6 27.7 81.9 -5.2 258 1.3
8500 15.7 60.3 255 4 2 8.4 4.6 27.6 81.7 -5.3 232 1.2
8250 16.3 61.3 280 5 3 8.4 4.6 27.5 81.5 -5.4 205 1.0
8000 17.0 62.6 300 8 4 8.4 4.6 27.4 81.3 -5.5 179 0.9
7750 17.6 63.7 300 7 4 8.4 4.6 27.3 81.1 -5.6 152 0.8
7500 18.2 64.8 305 5 2 8.4 4.6 27.2 80.9 -5.7 126 0.6
7250 18.9 66.0 300 2 1 8.4 4.6 27.1 80.7 -5.8 99 0.5
7000 19.5 67.1 075 1 0 8.4 4.6 27.0 80.5 -5.9 73 0.4
6750 20.1 68.2 085 3 2 8.4 4.6 26.8 80.3 -6.1 46 0.2
6500 20.8 69.4 105 4 2 8.4 4.6 26.7 80.1 -6.2 20 0.1
6250 21.4 70.5 115 6 3 8.3 4.6 26.6 79.9 -6.3 M M
6000 22.0 71.6 125 8 4 6.9 3.8 26.5 79.6 -6.5 M M
5750 22.5 72.5 115 9 4 8.2 4.5 26.3 79.3 -6.7 M M
5500 22.9 73.2 110 9 5 1.7 0.9 26.0 78.9 -7.0 M M
5250 22.2 72.0 120 7 4 -22.2 -12.2 24.6 76.3 -8.5 M M
5000 19.9 67.8 135 5 2 -34.1 -18.7 21.5 70.7 -11.5 1 0.0
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/25/2025 at 0900 MDT | 06/25/2025 at 1200 MDT
|
CAPE... +228.2 LI... -4.0 | CAPE... +700.6 LI... -3.7
CINH... -71.9 K Index... +26.2 | CINH... -3.5 K Index... +27.7
|
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 -60.5 -76.9 205 48 25 3.0 1.7 | -60.0 -76.0 210 48 25 2.1 1.1
45000 -56.2 -69.2 210 73 37 1.8 1.0 | -56.7 -70.1 210 67 35 2.5 1.4
40000 -53.0 -63.4 205 96 50 8.4 4.6 | -52.4 -62.3 210 83 43 7.4 4.0
38000 -48.4 -55.1 205 93 48 7.6 4.2 | -48.3 -54.9 210 84 43 6.8 3.7
36000 -43.9 -47.0 205 91 47 7.6 4.2 | -44.2 -47.6 205 85 44 6.8 3.7
34000 -40.3 -40.5 205 86 44 5.1 2.8 | -40.5 -40.9 205 82 42 5.9 3.3
32000 -37.2 -35.0 205 80 41 5.1 2.8 | -36.9 -34.4 205 77 40 6.0 3.3
30000 -34.6 -30.3 205 69 35 3.8 2.1 | -34.3 -29.7 210 65 33 3.3 1.8
29000 -33.5 -28.3 210 62 32 3.8 2.1 | -33.3 -27.9 210 57 29 3.3 1.8
28000 -32.4 -26.3 210 54 28 3.7 2.0 | -32.3 -26.1 210 49 25 3.2 1.7
27000 -30.0 -22.0 210 46 24 7.5 4.1 | -30.8 -23.4 215 43 22 6.4 3.5
26000 -27.7 -17.9 210 40 21 7.5 4.1 | -28.4 -19.1 215 36 19 6.4 3.5
25000 -25.5 -13.9 215 34 17 7.5 4.1 | -26.5 -15.7 215 31 16 6.3 3.5
24000 -23.3 -9.9 215 31 16 7.4 4.1 | -24.2 -11.6 210 29 15 8.0 4.4
23000 -21.1 -6.0 215 28 15 7.4 4.1 | -21.8 -7.2 210 28 14 8.1 4.4
22000 -18.9 -2.0 215 26 13 7.4 4.1 | -19.4 -2.9 210 26 14 8.1 4.4
21000 -16.7 1.9 215 25 13 7.3 4.0 | -17.1 1.2 215 25 13 7.9 4.3
20000 -14.6 5.7 215 24 13 7.3 4.0 | -14.8 5.4 215 24 12 7.9 4.3
19500 -13.5 7.7 215 24 12 7.2 4.0 | -13.6 7.5 215 23 12 7.9 4.3
19000 -12.4 9.7 215 24 12 8.1 4.5 | -12.4 9.7 215 23 12 8.3 4.6
18500 -11.2 11.8 215 23 12 8.2 4.5 | -11.2 11.8 215 22 11 8.4 4.6
18000 -10.0 14.0 210 23 12 8.4 4.6 | -10.0 14.0 220 21 11 8.6 4.7
17500 -8.7 16.3 210 23 12 9.0 4.9 | -8.6 16.5 220 20 10 9.0 4.9
17000 -7.3 18.9 210 22 11 9.0 4.9 | -7.3 18.9 220 19 10 9.0 4.9
16500 -6.0 21.2 210 22 11 9.1 5.0 | -6.0 21.2 220 19 10 9.0 4.9
16000 -4.7 23.5 205 21 11 9.1 5.0 | -4.6 23.7 225 18 9 9.0 4.9
15500 -3.3 26.1 205 21 11 9.1 5.0 | -3.3 26.1 225 17 9 9.2 5.0
15000 -2.0 28.4 205 21 11 9.1 5.0 | -1.9 28.6 225 17 9 9.2 5.1
14500 -0.6 30.9 205 20 10 9.1 5.0 | -0.6 30.9 225 16 8 9.2 5.1
14000 0.7 33.3 205 20 10 9.1 5.0 | 0.8 33.4 225 16 8 9.2 5.0
13500 2.0 35.6 205 19 10 9.1 5.0 | 2.1 35.8 225 15 8 9.2 5.0
13000 3.3 37.9 205 19 10 8.6 4.7 | 3.4 38.1 225 15 8 9.1 5.0
12500 4.5 40.1 205 18 9 8.7 4.8 | 4.8 40.6 225 14 7 9.1 5.0
12000 5.8 42.4 210 18 9 8.4 4.6 | 6.1 43.0 225 14 7 9.3 5.1
11500 6.9 44.4 210 17 9 8.5 4.6 | 7.4 45.3 230 14 7 9.3 5.1
11000 8.1 46.6 210 16 8 8.2 4.5 | 8.8 47.8 230 13 7 9.2 5.1
10500 9.3 48.7 215 15 8 8.2 4.5 | 10.1 50.2 230 12 6 7.6 4.2
10250 9.8 49.6 215 15 8 6.7 3.7 | 10.6 51.1 230 11 6 8.0 4.4
10000 10.3 50.5 215 14 7 7.6 4.2 | 11.3 52.3 235 11 6 10.5 5.8
9750 11.0 51.8 215 14 7 9.3 5.1 | 12.1 53.8 235 11 5 9.8 5.4
9500 11.6 52.9 215 13 7 8.9 4.9 | 12.8 55.0 235 10 5 10.1 5.5
9250 12.2 54.0 220 13 6 9.0 4.9 | 13.5 56.3 235 10 5 9.5 5.2
9000 13.5 56.3 220 11 6 7.8 4.3 | 14.2 57.6 240 9 5 9.0 5.0
8750 14.0 57.2 220 11 6 7.9 4.3 | 15.5 59.9 245 9 5 9.1 5.0
8500 14.6 58.3 220 10 5 7.0 3.9 | 16.2 61.2 245 9 5 8.2 4.5
8250 15.1 59.2 225 9 5 7.5 4.1 | 16.8 62.2 250 9 4 9.1 5.0
8000 15.7 60.3 225 8 4 9.4 5.1 | 17.6 63.7 250 9 4 11.0 6.0
7750 16.4 61.5 220 8 4 8.3 4.5 | 18.4 65.1 250 9 4 10.2 5.6
7500 16.9 62.4 220 7 4 5.9 3.2 | 19.1 66.4 250 9 4 8.7 4.7
7250 17.4 63.3 220 6 3 5.9 3.2 | 19.7 67.5 255 8 4 8.8 4.8
7000 18.0 64.4 215 5 2 9.9 5.4 | 20.5 68.9 255 8 4 11.4 6.2
6750 18.8 65.8 210 5 2 9.8 5.4 | 21.4 70.5 255 8 4 11.6 6.4
6500 19.4 66.9 210 4 2 7.6 4.2 | 22.2 72.0 255 8 4 10.8 5.9
6250 20.1 68.2 205 3 2 7.6 4.2 | 23.0 73.4 260 8 4 10.1 5.5
6000 20.7 69.3 200 2 1 10.0 5.5 | 23.8 74.8 260 8 4 12.5 6.9
5750 21.7 71.1 195 3 1 18.4 10.1 | 25.1 77.2 260 8 4 25.7 14.1
5500 23.2 73.8 200 1 1 16.2 8.9 | 27.6 81.7 265 7 4 42.3 23.2
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
06/25/2025 at 1500 MDT | 06/25/2025 at 1800 MDT
|
CAPE... +176.0 LI... -0.9 | CAPE... +4.0 LI... +0.3
CINH... -29.0 K Index... +21.3 | CINH... -16.0 K Index... +11.5
|
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 -60.0 -76.0 220 41 21 1.3 0.7 | -60.1 -76.2 220 34 18 1.1 0.6
45000 -57.0 -70.6 215 62 32 3.4 1.9 | -57.2 -71.0 220 56 29 3.9 2.1
40000 -51.8 -61.2 215 74 38 6.3 3.4 | -51.2 -60.2 230 64 33 5.4 3.0
38000 -48.2 -54.8 210 75 39 5.9 3.3 | -48.1 -54.6 230 59 30 5.3 2.9
36000 -44.6 -48.3 210 76 39 5.9 3.3 | -44.9 -48.8 230 55 28 5.2 2.9
34000 -41.4 -42.5 210 70 36 5.0 2.8 | -41.9 -43.4 230 48 25 5.0 2.7
32000 -38.4 -37.1 210 61 31 5.0 2.8 | -38.9 -38.0 235 41 21 5.0 2.7
30000 -35.1 -31.2 215 51 26 5.8 3.2 | -35.4 -31.7 240 34 18 6.2 3.4
29000 -33.4 -28.1 215 46 23 5.8 3.2 | -33.6 -28.5 240 31 16 6.2 3.4
28000 -31.6 -24.9 220 40 21 5.8 3.2 | -31.7 -25.1 240 28 15 6.2 3.4
27000 -29.4 -20.9 220 34 18 6.3 3.4 | -29.2 -20.6 240 25 13 6.9 3.8
26000 -27.5 -17.5 220 30 15 6.3 3.5 | -27.1 -16.8 240 23 12 6.9 3.8
25000 -25.6 -14.1 220 25 13 6.2 3.4 | -25.0 -13.0 240 21 11 6.9 3.8
24000 -23.5 -10.3 215 23 12 7.7 4.2 | -23.0 -9.4 235 20 10 6.9 3.8
23000 -21.2 -6.2 215 21 11 7.7 4.2 | -20.9 -5.6 230 19 10 7.0 3.8
22000 -18.9 -2.0 215 20 10 7.8 4.3 | -18.9 -2.0 225 18 9 7.2 4.0
21000 -16.5 2.3 215 19 10 8.0 4.4 | -16.5 2.3 225 18 9 8.5 4.7
20000 -14.2 6.4 215 18 9 8.0 4.4 | -13.9 7.0 225 17 9 8.5 4.7
19500 -13.0 8.6 215 18 9 8.0 4.4 | -12.7 9.1 225 17 9 8.5 4.7
19000 -11.8 10.8 215 18 9 8.2 4.5 | -11.4 11.5 225 17 8 8.9 4.9
18500 -10.6 12.9 215 18 9 8.2 4.5 | -10.1 13.8 225 16 8 8.9 4.9
18000 -9.4 15.1 215 17 9 8.3 4.5 | -8.7 16.3 225 16 8 9.0 4.9
17500 -8.1 17.4 215 17 9 8.4 4.6 | -7.4 18.7 225 16 8 9.1 5.0
17000 -6.9 19.6 220 17 9 8.3 4.6 | -6.0 21.2 225 16 8 9.0 5.0
16500 -5.6 21.9 220 17 9 9.3 5.1 | -4.6 23.7 225 15 8 9.7 5.3
16000 -4.2 24.4 220 17 9 9.2 5.1 | -3.2 26.2 230 15 8 9.6 5.3
15500 -2.8 27.0 220 16 8 9.4 5.2 | -1.7 28.9 230 15 8 9.4 5.2
15000 -1.4 29.5 225 16 8 9.5 5.2 | -0.3 31.5 230 15 8 9.4 5.1
14500 0.0 32.0 225 16 8 9.4 5.1 | 1.1 34.0 230 14 7 9.4 5.1
14000 1.4 34.5 225 16 8 9.1 5.0 | 2.5 36.5 235 14 7 9.4 5.2
13500 2.7 36.9 230 15 8 9.2 5.0 | 3.9 39.0 235 14 7 9.4 5.2
13000 4.1 39.4 230 15 8 9.4 5.1 | 5.3 41.5 240 13 7 9.3 5.1
12500 5.5 41.9 230 15 8 9.4 5.1 | 6.7 44.1 240 13 7 9.4 5.1
12000 6.9 44.4 235 15 8 9.4 5.2 | 8.1 46.6 245 13 6 9.2 5.1
11500 8.3 46.9 235 14 7 9.5 5.2 | 9.5 49.1 250 12 6 9.5 5.2
11000 9.7 49.5 240 14 7 8.5 4.7 | 10.8 51.4 250 12 6 7.6 4.1
10500 10.9 51.6 240 14 7 10.4 5.7 | 11.9 53.4 255 12 6 10.1 5.5
10250 11.8 53.2 240 14 7 10.8 5.9 | 12.8 55.0 255 11 6 12.2 6.7
10000 12.5 54.5 240 13 7 8.8 4.8 | 13.6 56.5 260 11 6 9.5 5.2
9750 13.2 55.8 240 13 7 9.3 5.1 | 14.3 57.7 260 10 5 9.0 4.9
9500 13.8 56.8 245 13 7 9.2 5.0 | 15.7 60.3 260 10 5 8.0 4.4
9250 14.5 58.1 245 13 7 9.3 5.1 | 16.2 61.2 260 10 5 8.7 4.8
9000 15.9 60.6 245 12 6 8.8 4.8 | 17.0 62.6 260 10 5 10.6 5.8
8750 16.5 61.7 245 12 6 8.9 4.9 | 17.7 63.9 260 9 5 10.2 5.6
8500 17.2 63.0 245 12 6 8.6 4.7 | 18.5 65.3 265 9 5 9.0 5.0
8250 17.8 64.0 250 11 6 9.1 5.0 | 19.1 66.4 265 10 5 9.1 5.0
8000 18.5 65.3 250 11 6 10.1 5.5 | 19.9 67.8 265 10 5 10.6 5.8
7750 19.3 66.7 245 10 5 9.5 5.2 | 20.6 69.1 265 9 5 10.0 5.5
7500 19.9 67.8 245 10 5 8.0 4.4 | 21.3 70.3 265 9 5 8.8 4.8
7250 20.5 68.9 250 10 5 8.2 4.5 | 22.0 71.6 265 10 5 8.7 4.8
7000 21.2 70.2 250 10 5 10.7 5.9 | 22.7 72.9 270 9 5 10.7 5.9
6750 22.0 71.6 245 9 4 10.8 5.9 | 23.5 74.3 265 8 4 11.1 6.1
6500 22.7 72.9 250 9 4 9.7 5.3 | 24.3 75.7 265 8 4 10.4 5.7
6250 23.5 74.3 250 8 4 9.4 5.2 | 25.1 77.2 270 9 4 10.4 5.7
6000 24.2 75.6 255 8 4 10.3 5.6 | 25.9 78.6 270 9 5 9.2 5.0
5750 25.2 77.4 245 7 4 18.6 10.2 | 26.6 79.9 265 7 4 13.0 7.1
5500 27.1 80.8 260 7 3 37.1 20.4 | 28.5 83.3 275 7 4 43.9 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
________________________________________________________________________________
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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