Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
195
UXUS97 KGJT 041305
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
705 AM MDT Monday, August 4, 2025
This forecast is for Monday, August 4, 2025:
If the trigger temperature of 83.2 F/28.4 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1715 ft/min (8.7 m/s)
Maximum height of thermals.................. 23459 ft MSL (17851 ft AGL)
Forecast maximum temperature................... 98.0 F/37.1 C
Time of trigger temperature.................... 1015 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................. 18802 ft MSL (13193 ft AGL)
Thermal soaring outlook for Tuesday 08/05...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:17:56 / 20:22:29 MDT
Total possible sunshine........... 14 hr 4 min 33 sec (844 min 33 sec)
Altitude of sun at 13:20:12 MDT... 67.46 degrees
Upper air data from rawinsonde observation taken on 08/04/2025 at 0600 MDT
Freezing level.................. 16243 ft MSL (10635 ft AGL)
Convective condensation level... 23634 ft MSL (18026 ft AGL)
Lifted condensation level....... 23876 ft MSL (18268 ft AGL)
Lifted index.................... +0.1
K index......................... +6.1
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 -64.0 -83.2 250 39 20 1.1 0.6 M M M M M
45000 -61.0 -77.8 250 63 32 4.0 2.2 M M M M M
40000 -54.3 -65.7 255 72 37 7.7 4.2 M M M M M
38000 -49.7 -57.5 255 69 36 7.8 4.3 M M M M M
36000 -44.4 -47.9 255 66 34 7.7 4.2 M M M M M
34000 -40.0 -40.0 255 63 33 7.3 4.0 M M M M M
32000 -35.6 -32.1 260 60 31 8.0 4.4 M M M M M
30000 -31.5 -24.7 255 55 28 7.0 3.8 43.2 109.7 4.9 M M
29000 -29.4 -20.9 255 52 27 7.0 3.8 42.2 107.9 4.1 M M
28000 -27.3 -17.1 250 50 26 7.3 4.0 41.2 106.2 3.4 M M
27000 -25.1 -13.2 250 48 25 7.4 4.0 40.2 104.4 2.7 M M
26000 -22.9 -9.2 250 46 24 7.4 4.1 39.3 102.8 2.0 M M
25000 -20.7 -5.3 250 44 23 7.4 4.0 38.5 101.4 1.3 M M
24000 -18.6 -1.5 250 42 22 7.2 4.0 37.5 99.6 0.5 M M
23000 -16.4 2.5 245 40 20 7.2 4.0 36.6 97.9 -0.3 1680 8.5
22000 -14.3 6.3 245 38 19 7.4 4.1 35.8 96.4 -1.0 1586 8.1
21000 -12.0 10.4 245 37 19 7.8 4.3 35.0 95.0 -1.7 1486 7.5
20000 -9.0 15.8 240 36 18 7.8 4.3 34.2 93.5 -2.4 1361 6.9
19500 -7.8 18.0 240 35 18 7.9 4.3 33.9 93.0 -2.6 1311 6.7
19000 -6.7 19.9 235 35 18 8.0 4.4 33.6 92.4 -2.9 1261 6.4
18500 -5.5 22.1 235 35 18 8.1 4.4 33.3 91.9 -3.2 1211 6.1
18000 -4.3 24.3 235 35 18 8.3 4.5 33.0 91.4 -3.5 1160 5.9
17500 -3.0 26.6 230 34 18 8.3 4.5 32.7 90.9 -3.8 1108 5.6
17000 -1.8 28.8 230 34 18 8.5 4.7 32.5 90.5 -4.0 1056 5.4
16500 -0.5 31.1 230 35 18 8.7 4.8 32.3 90.2 -4.2 1002 5.1
16000 0.8 33.4 230 35 18 8.7 4.8 32.2 89.9 -4.4 949 4.8
15500 2.0 35.6 230 35 18 8.0 4.4 31.9 89.5 -4.6 897 4.6
15000 3.2 37.8 235 35 18 8.1 4.4 31.6 89.0 -4.9 846 4.3
14500 4.4 39.9 235 34 18 7.9 4.4 31.4 88.5 -5.2 796 4.0
14000 5.6 42.1 235 33 17 7.9 4.4 31.1 87.9 -5.5 746 3.8
13500 6.8 44.2 240 33 17 8.1 4.4 30.8 87.4 -5.8 696 3.5
13000 8.0 46.4 240 32 16 8.1 4.5 30.5 86.9 -6.1 645 3.3
12500 9.2 48.6 245 31 16 8.2 4.5 30.3 86.5 -6.4 594 3.0
12000 10.4 50.7 245 30 15 8.4 4.6 30.0 86.1 -6.7 541 2.7
11500 11.7 53.1 245 28 15 8.0 4.4 29.8 85.7 -6.9 489 2.5
11000 12.8 55.0 245 27 14 7.2 4.0 29.5 85.0 -7.3 440 2.2
10500 14.0 57.2 245 26 13 9.9 5.5 29.2 84.6 -7.5 389 2.0
10250 14.8 58.6 245 25 13 9.3 5.1 29.2 84.6 -7.5 359 1.8
10000 15.4 59.7 245 24 12 7.8 4.3 29.1 84.4 -7.7 333 1.7
9750 16.0 60.8 245 24 12 8.4 4.6 29.0 84.2 -7.8 308 1.6
9500 16.6 61.9 245 23 12 7.6 4.1 28.9 83.9 -7.9 282 1.4
9250 17.2 63.0 245 22 12 7.9 4.3 28.7 83.6 -8.2 258 1.3
9000 17.8 64.0 245 21 11 8.5 4.7 28.6 83.4 -8.3 232 1.2
8750 18.4 65.1 245 20 10 9.1 5.0 28.5 83.3 -8.4 205 1.0
8500 19.1 66.4 245 19 10 6.3 3.5 28.4 83.1 -8.5 178 0.9
8250 19.4 66.9 245 17 9 4.1 2.3 28.0 82.3 -8.9 162 0.8
8000 19.8 67.6 240 15 8 5.4 3.0 27.6 81.7 -9.3 143 0.7
7750 20.2 68.4 235 13 7 5.5 3.0 27.3 81.1 -9.6 123 0.6
7500 20.6 69.1 230 11 6 4.0 2.2 26.9 80.5 -10.0 104 0.5
7250 20.8 69.4 225 9 5 2.6 1.4 26.4 79.5 -10.5 90 0.5
7000 21.0 69.8 220 8 4 3.9 2.1 25.9 78.6 -11.0 75 0.4
6750 21.3 70.3 210 7 4 2.5 1.4 25.4 77.8 -11.5 59 0.3
6500 21.4 70.5 195 6 3 -1.8 -1.0 24.7 76.5 -12.3 51 0.3
6250 21.1 70.0 180 6 3 -5.7 -3.1 23.7 74.7 -13.3 51 0.3
6000 20.9 69.6 165 7 4 4.4 2.4 22.7 72.9 -14.2 50 0.3
5750 21.3 70.3 150 6 3 -3.5 -1.9 22.4 72.4 -14.6 30 0.2
5500 M M M M M M M M M M M M
5250 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
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
08/04/2025 at 0900 MDT | 08/04/2025 at 1200 MDT
|
CAPE... 0.0 LI... +3.6 | CAPE... 0.0 LI... +3.7
CINH... -0.2 K Index... -5.7 | CINH... -0.1 K Index... -6.6
|
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 -63.0 -81.4 250 25 13 1.0 0.5 | -63.4 -82.1 250 29 15 0.6 0.3
45000 -60.1 -76.2 270 44 23 4.1 2.3 | -60.9 -77.6 265 44 23 4.3 2.4
40000 -53.5 -64.3 275 65 34 7.3 4.0 | -53.8 -64.8 265 58 30 7.5 4.1
38000 -48.5 -55.3 270 63 33 7.4 4.1 | -48.7 -55.7 265 56 29 7.6 4.2
36000 -44.1 -47.4 270 62 32 7.3 4.0 | -44.1 -47.4 265 53 27 7.6 4.2
34000 -39.7 -39.5 270 56 29 7.2 3.9 | -39.7 -39.5 270 49 25 7.4 4.0
32000 -35.4 -31.7 275 50 26 7.1 3.9 | -35.3 -31.5 270 45 23 7.3 4.0
30000 -31.0 -23.8 270 47 24 7.5 4.1 | -30.7 -23.3 265 42 22 7.6 4.2
29000 -28.7 -19.7 270 45 23 7.5 4.1 | -28.5 -19.3 265 40 21 7.6 4.2
28000 -26.4 -15.5 270 43 22 7.2 3.9 | -26.2 -15.2 265 39 20 7.1 3.9
27000 -24.3 -11.7 265 41 21 7.0 3.9 | -24.1 -11.4 265 37 19 7.0 3.8
26000 -22.2 -8.0 265 38 20 7.0 3.9 | -22.0 -7.6 260 35 18 7.0 3.8
25000 -20.1 -4.2 265 36 18 7.0 3.9 | -19.9 -3.8 260 33 17 7.0 3.8
24000 -18.0 -0.4 265 34 17 7.0 3.8 | -17.7 0.1 260 31 16 7.3 4.0
23000 -15.4 4.3 260 31 16 7.0 3.8 | -15.0 5.0 260 30 15 7.3 4.0
22000 -13.3 8.1 255 30 15 7.4 4.1 | -12.8 9.0 255 29 15 7.3 4.0
21000 -11.1 12.0 250 28 15 7.5 4.1 | -10.7 12.7 250 29 15 7.3 4.0
20000 -8.8 16.2 245 27 14 7.5 4.1 | -8.5 16.7 250 28 15 7.3 4.0
19500 -7.7 18.1 245 27 14 7.5 4.1 | -7.4 18.7 245 28 15 7.4 4.1
19000 -6.6 20.1 240 26 13 7.4 4.0 | -6.2 20.8 245 28 14 7.8 4.3
18500 -5.5 22.1 240 26 13 7.4 4.0 | -5.1 22.8 245 27 14 7.8 4.3
18000 -4.4 24.1 240 25 13 7.6 4.2 | -3.9 25.0 245 27 14 7.6 4.2
17500 -3.3 26.1 235 25 13 7.6 4.2 | -2.8 27.0 240 26 13 7.6 4.2
17000 -2.2 28.0 235 24 12 7.8 4.3 | -1.7 28.9 240 25 13 7.6 4.1
16500 -1.0 30.2 230 23 12 8.2 4.5 | -0.6 30.9 240 24 12 7.4 4.1
16000 0.2 32.4 230 22 12 8.1 4.5 | 0.5 32.9 235 23 12 7.4 4.1
15500 1.4 34.5 230 22 11 8.4 4.6 | 1.6 34.9 230 22 11 7.7 4.2
15000 2.7 36.9 230 21 11 8.4 4.6 | 2.8 37.0 230 21 11 7.7 4.2
14500 3.9 39.0 230 21 11 8.5 4.7 | 3.9 39.0 225 20 10 8.2 4.5
14000 5.2 41.4 230 20 10 8.6 4.7 | 5.1 41.2 225 19 10 8.3 4.6
13500 6.5 43.7 230 20 10 8.6 4.7 | 6.4 43.5 220 19 10 8.6 4.7
13000 7.8 46.0 230 19 10 8.6 4.7 | 7.7 45.9 220 18 9 8.9 4.9
12500 9.1 48.4 230 18 9 8.6 4.7 | 9.0 48.2 220 17 9 8.9 4.9
12000 10.3 50.5 230 18 9 8.5 4.7 | 10.3 50.5 220 16 8 8.9 4.9
11500 11.6 52.9 235 17 9 8.5 4.6 | 11.7 53.1 220 15 8 9.0 4.9
11000 12.8 55.0 235 16 8 8.1 4.4 | 13.0 55.4 225 15 8 8.9 4.9
10500 14.1 57.4 235 15 8 5.1 2.8 | 14.4 57.9 225 14 7 6.3 3.5
10250 14.4 57.9 235 15 8 5.8 3.2 | 14.7 58.5 225 13 6 7.0 3.8
10000 15.0 59.0 235 14 7 10.2 5.6 | 15.5 59.9 225 12 6 10.9 6.0
9750 15.7 60.3 235 14 7 9.1 5.0 | 16.2 61.2 225 12 6 10.0 5.5
9500 16.4 61.5 235 14 7 8.9 4.9 | 17.0 62.6 225 12 6 9.8 5.4
9250 17.0 62.6 235 13 7 6.9 3.8 | 17.7 63.9 225 11 6 8.8 4.8
9000 17.5 63.5 235 12 6 6.7 3.7 | 18.3 64.9 230 10 5 9.0 4.9
8750 18.0 64.4 230 11 6 7.6 4.2 | 19.0 66.2 230 10 5 9.5 5.2
8500 18.6 65.5 225 11 6 7.1 3.9 | 19.7 67.5 230 10 5 9.0 4.9
8250 19.6 67.3 220 9 5 6.0 3.3 | 20.4 68.7 230 9 5 7.4 4.0
8000 20.0 68.0 210 9 5 5.6 3.0 | 21.7 71.1 230 8 4 11.9 6.5
7750 20.4 68.7 200 9 5 4.9 2.7 | 22.6 72.7 230 9 4 9.9 5.5
7500 20.7 69.3 190 9 4 3.9 2.1 | 23.2 73.8 235 8 4 7.7 4.2
7250 21.0 69.8 185 9 4 4.1 2.2 | 23.8 74.8 235 7 4 8.9 4.9
7000 21.3 70.3 180 9 4 5.1 2.8 | 24.6 76.3 235 7 4 12.7 7.0
6750 21.7 71.1 170 9 4 5.0 2.8 | 25.6 78.1 235 8 4 11.8 6.5
6500 22.0 71.6 165 8 4 4.6 2.5 | 26.4 79.5 240 7 4 9.9 5.4
6250 22.4 72.3 155 8 4 4.2 2.3 | 27.1 80.8 240 6 3 9.4 5.2
6000 22.7 72.9 145 7 4 7.8 4.3 | 27.9 82.2 245 6 3 13.1 7.2
5750 23.6 74.5 145 6 3 16.8 9.2 | 29.3 84.7 240 6 3 26.3 14.4
5500 24.7 76.5 135 6 3 6.7 3.7 | 31.4 88.5 250 5 2 25.2 13.8
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
08/04/2025 at 1500 MDT | 08/04/2025 at 1800 MDT
|
CAPE... 0.0 LI... +1.4 | CAPE... 0.0 LI... +1.4
CINH... -0.1 K Index... -4.6 | CINH... -0.1 K Index... -6.4
|
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 -63.7 -82.7 255 30 15 0.2 0.1 | -63.6 -82.5 255 28 14 0.9 0.5
45000 -61.4 -78.5 265 47 24 4.7 2.6 | -60.8 -77.4 260 48 25 4.1 2.2
40000 -53.9 -65.0 265 59 30 7.8 4.3 | -54.0 -65.2 260 62 32 7.9 4.3
38000 -48.6 -55.5 265 55 28 7.9 4.3 | -48.6 -55.5 260 59 30 8.0 4.4
36000 -43.8 -46.8 260 52 27 7.6 4.2 | -43.7 -46.7 260 56 29 7.7 4.2
34000 -39.6 -39.3 260 48 24 6.9 3.8 | -39.8 -39.6 260 51 26 6.6 3.6
32000 -35.5 -31.9 260 43 22 7.1 3.9 | -35.8 -32.4 255 47 24 6.3 3.4
30000 -30.9 -23.6 260 40 21 7.7 4.2 | -31.5 -24.7 255 43 22 7.4 4.1
29000 -28.6 -19.5 260 39 20 7.7 4.2 | -29.2 -20.6 255 41 21 7.4 4.1
28000 -26.3 -15.3 260 38 19 7.3 4.0 | -27.0 -16.6 255 39 20 7.5 4.1
27000 -24.2 -11.6 255 37 19 7.2 3.9 | -24.7 -12.5 255 38 19 7.5 4.1
26000 -22.0 -7.6 255 36 18 7.2 3.9 | -22.5 -8.5 255 37 19 7.5 4.1
25000 -19.9 -3.8 255 35 18 7.2 3.9 | -20.2 -4.4 255 35 18 7.6 4.2
24000 -17.7 0.1 255 34 17 7.1 3.9 | -17.9 -0.2 255 33 17 7.8 4.3
23000 -15.1 4.8 255 32 16 7.1 3.9 | -15.0 5.0 255 31 16 7.8 4.3
22000 -12.9 8.8 255 30 16 7.4 4.0 | -12.7 9.1 255 29 15 7.7 4.2
21000 -10.7 12.7 255 29 15 7.4 4.1 | -10.4 13.3 255 27 14 7.7 4.2
20000 -8.5 16.7 250 28 14 7.4 4.1 | -8.1 17.4 250 26 13 7.7 4.2
19500 -7.4 18.7 250 28 14 7.5 4.1 | -6.9 19.6 250 25 13 7.7 4.2
19000 -6.3 20.7 245 27 14 7.7 4.2 | -5.8 21.6 250 24 12 7.8 4.3
18500 -5.1 22.8 245 26 13 7.7 4.2 | -4.6 23.7 245 24 12 7.8 4.3
18000 -4.0 24.8 240 25 13 8.4 4.6 | -3.5 25.7 245 23 12 8.2 4.5
17500 -2.7 27.1 240 24 12 8.5 4.6 | -2.3 27.9 240 23 12 8.2 4.5
17000 -1.5 29.3 235 23 12 8.6 4.7 | -1.0 30.2 240 22 11 8.5 4.7
16500 -0.2 31.6 235 23 12 8.9 4.9 | 0.3 32.5 235 22 11 9.0 5.0
16000 1.1 34.0 230 22 11 8.8 4.8 | 1.6 34.9 235 22 11 9.0 4.9
15500 2.5 36.5 230 22 11 9.3 5.1 | 3.0 37.4 235 21 11 9.5 5.2
15000 3.9 39.0 230 21 11 9.2 5.1 | 4.4 39.9 235 21 11 9.5 5.2
14500 5.2 41.4 225 21 11 9.2 5.1 | 5.8 42.4 235 21 11 9.3 5.1
14000 6.6 43.9 225 20 10 9.2 5.1 | 7.2 45.0 235 21 11 9.3 5.1
13500 8.0 46.4 225 19 10 9.3 5.1 | 8.6 47.5 235 20 10 9.4 5.1
13000 9.4 48.9 225 19 10 9.3 5.1 | 10.0 50.0 235 20 10 9.4 5.2
12500 10.8 51.4 225 18 10 9.3 5.1 | 11.4 52.5 235 20 10 9.4 5.2
12000 12.1 53.8 225 18 9 9.1 5.0 | 12.8 55.0 235 19 10 9.4 5.1
11500 13.5 56.3 225 17 9 9.0 4.9 | 14.2 57.6 235 19 10 9.2 5.1
11000 14.8 58.6 230 17 9 8.6 4.7 | 15.5 59.9 235 19 10 7.8 4.3
10500 16.0 60.8 230 16 8 9.9 5.4 | 16.6 61.9 235 18 9 11.7 6.4
10250 16.9 62.4 230 16 8 10.6 5.8 | 17.7 63.9 235 18 9 12.5 6.9
10000 17.6 63.7 235 16 8 9.2 5.1 | 18.3 64.9 240 18 9 8.0 4.4
9750 18.3 64.9 235 16 8 9.5 5.2 | 19.0 66.2 240 18 9 9.3 5.1
9500 19.0 66.2 235 15 8 9.6 5.3 | 19.7 67.5 240 17 9 8.4 4.6
9250 19.7 67.5 240 15 8 10.0 5.5 | 20.3 68.5 240 17 9 8.2 4.5
9000 20.5 68.9 240 15 8 9.8 5.4 | 20.9 69.6 245 17 9 9.5 5.2
8750 21.9 71.4 240 15 8 9.7 5.3 | 22.4 72.3 245 16 8 9.8 5.4
8500 22.7 72.9 245 15 8 9.3 5.1 | 23.1 73.6 245 16 8 8.9 4.9
8250 23.4 74.1 245 15 8 9.9 5.4 | 23.8 74.8 250 16 8 9.5 5.2
8000 24.1 75.4 245 15 8 10.9 6.0 | 24.6 76.3 250 16 8 10.7 5.9
7750 24.9 76.8 245 15 8 10.0 5.5 | 25.3 77.5 250 16 8 10.0 5.5
7500 25.6 78.1 245 15 8 8.5 4.7 | 26.0 78.8 250 16 8 8.7 4.8
7250 26.3 79.3 250 15 8 9.1 5.0 | 26.7 80.1 250 16 8 9.0 4.9
7000 27.0 80.6 250 15 7 11.5 6.3 | 27.4 81.3 250 15 8 10.9 6.0
6750 27.9 82.2 250 14 7 11.6 6.4 | 28.2 82.8 250 15 8 10.9 6.0
6500 28.8 83.8 250 14 7 11.1 6.1 | 29.0 84.2 250 14 7 10.3 5.6
6250 29.6 85.3 255 14 7 10.5 5.8 | 29.8 85.6 250 14 7 10.2 5.6
6000 30.4 86.7 255 14 7 11.4 6.2 | 30.5 86.9 255 14 7 9.3 5.1
5750 31.5 88.7 250 12 6 22.7 12.5 | 31.3 88.3 250 12 6 13.2 7.2
5500 34.2 93.6 255 12 6 53.9 29.6 | 33.0 91.4 255 12 6 39.7 21.8
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.
042613