Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
294
UXUS97 KGJT 241307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Tuesday, September 24, 2024
This forecast is for Tuesday, September 24, 2024:
If the trigger temperature of 74.5 F/23.6 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 672 ft/min (3.4 m/s)
Maximum height of thermals.................. 13517 ft MSL (8678 ft AGL)
Forecast maximum temperature................... 84.0 F/29.3 C
Time of trigger temperature.................... 1145 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................. 10918 ft MSL (6079 ft AGL)
Thermal soaring outlook for Wednesday 09/25.... Good
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:04:28 / 19:07:19 MDT
Total possible sunshine........... 12 hr 2 min 51 sec (722 min 51 sec)
Altitude of sun at 13:05:54 MDT... 49.98 degrees
Upper air data from rawinsonde observation taken on 09/24/2024 at 0600 MDT
Freezing level.................. 16317 ft MSL (11478 ft AGL)
Convective condensation level... 21461 ft MSL (16622 ft AGL)
Lifted condensation level....... 16773 ft MSL (11933 ft AGL)
Lifted index.................... +6.0
K index......................... +5.6
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 -66.5 -87.7 025 20 10 7.4 4.1 84.3 183.7 32.0 M M
45000 -61.6 -78.9 030 58 30 0.3 0.2 67.1 152.8 23.8 M M
40000 -55.7 -68.3 045 58 30 6.7 3.7 53.6 128.5 16.5 M M
38000 -51.5 -60.7 050 49 25 7.5 4.1 51.2 124.2 15.3 M M
36000 -46.8 -52.2 050 38 20 8.1 4.4 49.5 121.0 14.4 M M
34000 -41.3 -42.3 040 38 20 9.4 5.2 49.0 120.2 14.5 M M
32000 -35.6 -32.1 030 36 19 10.2 5.6 47.9 118.1 14.0 M M
30000 -30.1 -22.2 025 35 18 8.9 4.9 47.5 117.5 14.1 M M
29000 -27.4 -17.3 025 34 18 8.9 4.9 47.1 116.8 14.0 M M
28000 -24.8 -12.6 025 37 19 8.5 4.7 46.7 116.1 13.8 M M
27000 -22.2 -8.0 020 33 17 8.4 4.6 46.2 115.2 13.6 M M
26000 -19.8 -3.6 020 30 16 8.2 4.5 45.6 114.1 13.2 M M
25000 -17.4 0.7 015 28 14 7.8 4.3 45.0 113.0 12.8 M M
24000 -15.6 3.9 020 28 14 6.2 3.4 43.7 110.7 11.9 M M
23000 -13.1 8.4 030 28 14 8.8 4.8 43.2 109.8 11.6 M M
22000 -10.5 13.1 025 25 13 8.8 4.8 42.9 109.1 11.4 M M
21000 -8.2 17.2 015 23 12 5.2 2.8 42.1 107.8 10.9 M M
20000 -6.3 20.7 015 19 10 6.2 3.4 40.9 105.7 10.0 M M
19500 -5.3 22.5 015 18 9 6.5 3.6 40.3 104.6 9.5 M M
19000 -4.5 23.9 010 15 8 4.9 2.7 39.7 103.4 8.9 M M
18500 -3.8 25.2 010 13 7 4.8 2.6 38.8 101.8 8.2 M M
18000 -3.1 26.4 020 18 10 4.8 2.6 37.9 100.3 7.5 M M
17500 -2.5 27.5 015 20 11 4.8 2.6 37.1 98.8 6.7 M M
17000 -1.2 29.8 360 17 9 7.1 3.9 36.1 96.9 5.8 M M
16500 -0.2 31.6 355 18 10 6.9 3.8 35.6 96.1 5.5 M M
16000 0.9 33.6 355 20 10 6.8 3.7 35.1 95.3 5.1 M M
15500 1.9 35.4 360 23 12 5.1 2.8 34.7 94.4 4.7 M M
15000 2.5 36.5 355 22 11 2.2 1.2 33.6 92.5 3.8 M M
14500 2.1 35.8 335 18 9 -5.1 -2.8 31.6 88.9 2.0 M M
14000 2.0 35.6 320 18 9 4.6 2.5 29.8 85.7 0.5 M M
13500 2.9 37.2 305 19 10 5.6 3.1 29.2 84.6 -0.1 667 3.4
13000 3.6 38.5 310 15 8 6.6 3.6 28.6 83.4 -0.8 630 3.2
12500 4.7 40.5 310 14 7 7.1 3.9 28.2 82.7 -1.2 582 3.0
12000 5.7 42.3 300 9 4 6.4 3.5 27.7 81.8 -1.7 539 2.7
11500 6.6 43.9 295 4 2 6.3 3.5 27.2 80.9 -2.3 497 2.5
11000 7.4 45.3 350 5 2 4.9 2.7 26.5 79.7 -2.9 457 2.3
10500 8.2 46.8 085 4 2 5.1 2.8 25.7 78.3 -3.6 420 2.1
10250 8.6 47.5 090 6 3 6.6 3.6 25.4 77.7 -3.9 399 2.0
10000 9.1 48.4 095 7 4 7.4 4.1 25.2 77.4 -4.1 376 1.9
9750 9.7 49.5 090 7 4 7.2 4.0 25.0 77.0 -4.3 353 1.8
9500 10.2 50.4 090 8 4 7.3 4.0 24.8 76.7 -4.5 329 1.7
9250 10.8 51.4 085 9 4 7.3 4.0 24.6 76.3 -4.7 306 1.6
9000 11.3 52.3 080 10 5 7.3 4.0 24.4 76.0 -4.9 282 1.4
8750 11.8 53.2 070 10 5 7.3 4.0 24.2 75.6 -5.1 259 1.3
8500 12.4 54.3 065 11 6 7.3 4.0 24.1 75.3 -5.3 235 1.2
8250 12.9 55.2 055 10 5 7.3 4.0 23.9 75.0 -5.5 212 1.1
8000 13.4 56.1 040 9 5 7.3 4.0 23.7 74.6 -5.7 189 1.0
7750 14.0 57.2 045 9 4 7.2 4.0 23.5 74.2 -6.0 165 0.8
7500 14.5 58.1 050 7 4 8.0 4.4 23.3 73.9 -6.2 141 0.7
7250 15.1 59.2 060 7 3 8.5 4.7 23.2 73.8 -6.3 115 0.6
7000 15.8 60.4 055 5 3 8.5 4.7 23.1 73.6 -6.4 89 0.5
6750 16.4 61.5 050 5 3 8.1 4.4 23.0 73.4 -6.5 63 0.3
6500 16.9 62.4 045 5 2 8.1 4.5 22.9 73.1 -6.7 39 0.2
6250 17.4 63.3 060 4 2 2.9 1.6 22.6 72.7 -7.0 17 0.1
6000 17.2 63.0 115 8 4 -5.8 -3.2 21.7 71.1 -7.9 15 0.1
5750 16.6 61.9 130 11 6 -7.8 -4.3 20.4 68.8 -9.3 26 0.1
5500 16.0 60.8 135 13 7 -7.3 -4.0 19.1 66.4 -10.6 36 0.2
5250 15.5 59.9 140 15 7 -7.1 -3.9 17.8 64.1 -11.9 47 0.2
5000 14.9 58.8 135 16 8 -8.5 -4.7 16.6 61.8 -13.3 57 0.3
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
09/24/2024 at 0900 MDT | 09/24/2024 at 1200 MDT
|
CAPE... 0.0 LI... +9.2 | CAPE... 0.0 LI... +8.6
CINH... -0.3 K Index... +7.7 | CINH... -0.0 K Index... +7.6
|
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 -64.2 -83.6 025 32 16 1.2 0.7 | -65.4 -85.7 030 25 13 1.9 1.1
45000 -61.1 -78.0 030 45 23 3.8 2.1 | -61.4 -78.5 035 36 19 4.0 2.2
40000 -54.7 -66.5 045 50 26 7.1 3.9 | -54.9 -66.8 045 43 22 7.3 4.0
38000 -50.5 -58.9 045 45 23 7.1 3.9 | -50.4 -58.7 045 37 19 7.4 4.1
36000 -46.2 -51.2 050 39 20 7.0 3.8 | -46.0 -50.8 045 31 16 7.3 4.0
34000 -41.0 -41.8 045 33 17 8.8 4.9 | -40.2 -40.4 040 25 13 8.8 4.8
32000 -35.7 -32.3 040 27 14 8.8 4.8 | -34.9 -30.8 035 20 10 9.0 5.0
30000 -30.3 -22.5 025 29 15 8.9 4.9 | -29.5 -21.1 025 21 11 9.1 5.0
29000 -27.7 -17.9 020 31 16 8.9 4.9 | -26.8 -16.2 020 22 11 9.2 5.0
28000 -25.0 -13.0 015 33 17 8.3 4.6 | -24.1 -11.4 015 23 12 7.9 4.3
27000 -22.1 -7.8 015 31 16 7.6 4.2 | -21.8 -7.2 010 23 12 7.6 4.2
26000 -19.9 -3.8 010 29 15 7.6 4.2 | -19.5 -3.1 010 24 12 7.6 4.2
25000 -17.6 0.3 010 27 14 7.5 4.1 | -17.3 0.9 005 24 12 7.6 4.1
24000 -15.4 4.3 015 25 13 7.4 4.0 | -15.3 4.5 360 23 12 6.5 3.6
23000 -13.2 8.2 015 22 11 7.4 4.1 | -13.4 7.9 355 21 11 6.6 3.6
22000 -11.0 12.2 020 20 10 7.3 4.0 | -11.4 11.5 350 20 10 6.7 3.7
21000 -8.9 16.0 015 20 11 7.2 4.0 | -8.8 16.2 355 19 10 7.4 4.1
20000 -6.7 19.9 015 21 11 7.3 4.0 | -6.6 20.1 355 19 10 7.4 4.1
19500 -5.7 21.7 015 21 11 7.4 4.1 | -5.5 22.1 360 18 9 7.3 4.0
19000 -4.7 23.5 015 22 11 5.8 3.2 | -4.5 23.9 360 18 9 6.5 3.6
18500 -3.8 25.2 015 22 11 6.0 3.3 | -3.6 25.5 005 18 9 6.6 3.6
18000 -3.0 26.6 015 22 11 5.8 3.2 | -2.6 27.3 010 18 9 5.9 3.2
17500 -2.2 28.0 015 21 11 5.5 3.0 | -1.8 28.8 010 18 9 5.7 3.1
17000 -1.4 29.5 010 21 11 5.6 3.1 | -1.0 30.2 015 18 9 5.6 3.1
16500 -0.6 30.9 010 21 11 5.2 2.8 | -0.3 31.5 020 18 9 5.1 2.8
16000 0.2 32.4 010 20 10 5.2 2.9 | 0.5 32.9 020 17 9 5.1 2.8
15500 0.9 33.6 010 20 10 3.7 2.0 | 1.2 34.2 025 17 9 4.9 2.7
15000 1.3 34.3 005 19 10 3.0 1.6 | 1.9 35.4 025 16 8 4.8 2.6
14500 1.8 35.2 005 18 9 2.4 1.3 | 2.6 36.7 025 15 8 4.3 2.3
14000 2.0 35.6 005 17 9 1.2 0.7 | 3.1 37.6 025 14 7 3.7 2.1
13500 2.2 36.0 360 15 8 1.4 0.8 | 3.7 38.7 030 13 7 3.4 1.9
13000 2.6 36.7 360 13 7 3.8 2.1 | 4.1 39.4 025 11 6 2.5 1.4
12500 3.2 37.8 355 10 5 3.4 1.9 | 4.5 40.1 020 10 5 2.7 1.5
12000 3.9 39.0 355 8 4 6.9 3.8 | 5.1 41.2 020 8 4 5.3 2.9
11500 4.9 40.8 360 6 3 6.5 3.6 | 5.9 42.6 015 6 3 5.1 2.8
11000 5.9 42.6 010 5 2 7.6 4.2 | 6.9 44.4 015 5 3 7.4 4.1
10500 7.0 44.6 020 5 2 7.6 4.2 | 7.9 46.2 015 4 2 6.3 3.4
10250 7.6 45.7 025 5 2 6.2 3.4 | 8.4 47.1 015 4 2 5.9 3.2
10000 8.0 46.4 025 5 3 6.7 3.7 | 8.9 48.0 015 4 2 8.2 4.5
9750 8.6 47.5 035 6 3 8.4 4.6 | 9.5 49.1 020 4 2 9.0 4.9
9500 9.2 48.6 040 6 3 7.9 4.3 | 10.2 50.4 025 3 2 8.6 4.7
9250 9.8 49.6 045 7 4 8.4 4.6 | 10.8 51.4 030 3 2 7.2 3.9
9000 10.9 51.6 050 8 4 6.6 3.6 | 11.3 52.3 035 3 2 7.6 4.2
8750 11.4 52.5 050 8 4 6.7 3.7 | 11.9 53.4 040 3 1 9.1 5.0
8500 11.9 53.4 055 8 4 6.5 3.6 | 12.6 54.7 045 3 1 8.1 4.4
8250 12.3 54.1 055 9 4 6.4 3.5 | 13.1 55.6 050 3 1 5.9 3.2
8000 12.8 55.0 055 9 4 6.9 3.8 | 14.2 57.6 055 2 1 11.1 6.1
7750 13.3 55.9 060 8 4 5.7 3.1 | 15.0 59.0 055 2 1 9.3 5.1
7500 13.6 56.5 065 8 4 3.8 2.1 | 15.5 59.9 060 2 1 6.2 3.4
7250 13.9 57.0 065 8 4 3.8 2.1 | 16.0 60.8 065 2 1 7.4 4.0
7000 14.2 57.6 070 8 4 4.5 2.4 | 16.7 62.1 065 2 1 12.6 6.9
6750 14.5 58.1 075 6 3 3.7 2.0 | 17.7 63.9 060 2 1 12.1 6.6
6500 14.7 58.5 080 5 3 2.7 1.5 | 18.4 65.1 065 1 1 9.0 5.0
6250 14.9 58.8 085 5 3 2.5 1.4 | 19.1 66.4 070 1 1 8.9 4.9
6000 15.1 59.2 090 5 2 5.2 2.9 | 19.9 67.8 075 1 1 13.5 7.4
5750 15.8 60.4 095 3 2 11.0 6.0 | 21.3 70.3 070 1 1 26.0 14.3
5500 16.3 61.3 100 3 1 -2.1 -1.1 | 23.0 73.4 085 1 1 8.7 4.8
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
09/24/2024 at 1500 MDT | 09/24/2024 at 1800 MDT
|
CAPE... 0.0 LI... +6.9 | CAPE... 0.0 LI... +6.3
CINH... -0.1 K Index... +7.3 | CINH... -0.1 K Index... +6.8
|
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 -65.9 -86.6 025 18 9 2.5 1.4 | -66.1 -87.0 020 13 7 2.3 1.2
45000 -61.3 -78.3 035 27 14 4.2 2.3 | -61.6 -78.9 035 18 9 4.7 2.6
40000 -54.6 -66.3 050 32 17 7.3 4.0 | -54.0 -65.2 055 23 12 7.1 3.9
38000 -50.1 -58.2 045 27 14 7.4 4.0 | -49.7 -57.5 055 21 11 7.1 3.9
36000 -45.2 -49.4 040 22 11 8.1 4.5 | -44.9 -48.8 050 18 9 8.1 4.4
34000 -39.9 -39.8 025 18 9 8.9 4.9 | -39.6 -39.3 030 15 8 8.9 4.9
32000 -34.6 -30.3 010 15 8 9.2 5.0 | -34.3 -29.7 010 15 7 9.2 5.1
30000 -29.1 -20.4 010 16 8 9.1 5.0 | -28.9 -20.0 010 13 7 9.1 5.0
29000 -26.4 -15.5 015 16 8 9.1 5.0 | -26.2 -15.2 010 13 7 9.1 5.0
28000 -23.7 -10.7 015 16 8 8.0 4.4 | -23.5 -10.3 010 12 6 8.1 4.4
27000 -21.4 -6.5 025 17 9 7.9 4.3 | -21.1 -6.0 025 13 7 8.1 4.4
26000 -19.0 -2.2 025 18 9 7.9 4.3 | -18.7 -1.7 035 14 7 8.1 4.4
25000 -16.7 1.9 030 19 10 7.7 4.2 | -16.3 2.7 045 16 8 7.9 4.3
24000 -14.6 5.7 030 18 9 6.9 3.8 | -14.1 6.6 045 15 8 7.1 3.9
23000 -12.6 9.3 030 17 9 6.9 3.8 | -12.0 10.4 050 14 7 7.1 3.9
22000 -10.0 14.0 030 16 8 6.4 3.5 | -9.4 15.1 055 13 7 6.3 3.5
21000 -8.2 17.2 025 15 8 6.3 3.4 | -7.6 18.3 050 12 6 6.1 3.4
20000 -6.3 20.7 020 14 7 6.3 3.5 | -5.8 21.6 050 11 6 6.2 3.4
19500 -5.4 22.3 015 13 7 6.4 3.5 | -4.8 23.4 050 11 6 6.2 3.4
19000 -4.4 24.1 015 13 7 6.5 3.6 | -3.9 25.0 050 11 6 6.3 3.5
18500 -3.5 25.7 020 13 7 6.6 3.6 | -3.0 26.6 045 11 6 6.3 3.5
18000 -2.5 27.5 020 12 6 6.6 3.6 | -2.1 28.2 045 11 6 6.4 3.5
17500 -1.6 29.1 025 12 6 6.7 3.7 | -1.1 30.0 050 11 6 6.5 3.5
17000 -0.6 30.9 025 12 6 6.6 3.6 | -0.2 31.6 050 11 6 6.4 3.5
16500 0.3 32.5 025 12 6 6.1 3.3 | 0.7 33.3 050 11 6 6.1 3.4
16000 1.2 34.2 030 12 6 6.2 3.4 | 1.6 34.9 050 11 6 6.2 3.4
15500 2.0 35.6 030 12 6 5.5 3.0 | 2.5 36.5 055 11 6 5.6 3.1
15000 2.8 37.0 030 12 6 5.5 3.0 | 3.3 37.9 055 11 6 5.5 3.0
14500 3.6 38.5 030 12 6 5.2 2.9 | 4.1 39.4 055 11 6 5.1 2.8
14000 4.3 39.7 030 11 6 5.0 2.8 | 4.7 40.5 050 11 6 4.8 2.6
13500 5.0 41.0 035 10 5 4.9 2.7 | 5.4 41.7 045 11 6 5.1 2.8
13000 5.7 42.3 035 10 5 4.5 2.4 | 6.2 43.2 045 11 6 6.1 3.4
12500 6.4 43.5 035 9 5 4.5 2.5 | 7.1 44.8 045 11 6 6.2 3.4
12000 7.1 44.8 030 8 4 5.0 2.7 | 8.1 46.6 040 11 6 7.0 3.8
11500 7.8 46.0 030 8 4 5.0 2.7 | 9.1 48.4 040 10 5 6.9 3.8
11000 8.8 47.8 025 7 4 7.4 4.1 | 10.2 50.4 040 10 5 8.0 4.4
10500 9.9 49.8 020 6 3 4.7 2.6 | 11.4 52.5 040 9 5 6.5 3.6
10250 10.1 50.2 020 6 3 6.0 3.3 | 11.8 53.2 040 10 5 7.2 4.0
10000 10.8 51.4 020 6 3 10.4 5.7 | 12.5 54.5 040 9 5 9.7 5.3
9750 11.6 52.9 015 5 3 9.3 5.1 | 13.2 55.8 035 8 4 9.0 5.0
9500 12.3 54.1 015 5 3 9.3 5.1 | 13.9 57.0 035 8 4 9.2 5.1
9250 12.9 55.2 010 5 2 7.9 4.4 | 14.6 58.3 035 7 4 9.0 4.9
9000 13.5 56.3 010 4 2 8.6 4.7 | 15.2 59.4 035 7 3 8.6 4.7
8750 14.2 57.6 010 4 2 10.0 5.5 | 15.9 60.6 035 6 3 8.6 4.7
8500 14.9 58.8 005 4 2 9.3 5.1 | 16.5 61.7 035 6 3 8.5 4.6
8250 15.5 59.9 005 4 2 6.9 3.8 | 17.1 62.8 030 5 2 6.9 3.8
8000 16.9 62.4 360 3 2 12.1 6.7 | 18.3 64.9 025 3 2 10.6 5.8
7750 17.7 63.9 360 3 2 10.2 5.6 | 19.1 66.4 020 3 1 9.2 5.1
7500 18.4 65.1 355 3 2 7.3 4.0 | 19.7 67.5 010 2 1 7.1 3.9
7250 18.9 66.0 350 3 1 8.1 4.4 | 20.2 68.4 355 1 1 7.4 4.0
7000 19.7 67.5 350 3 1 12.7 7.0 | 20.9 69.6 340 1 1 10.7 5.9
6750 20.7 69.3 350 3 1 12.0 6.6 | 21.7 71.1 340 1 1 10.8 5.9
6500 21.4 70.5 345 2 1 9.4 5.2 | 22.4 72.3 320 1 1 9.2 5.1
6250 22.1 71.8 335 2 1 9.3 5.1 | 23.1 73.6 290 1 1 9.5 5.2
6000 22.9 73.2 330 2 1 12.4 6.8 | 23.8 74.8 275 1 1 9.5 5.2
5750 24.2 75.6 335 2 1 23.5 12.9 | 24.6 76.3 295 1 1 11.4 6.3
5500 26.0 78.8 320 2 1 19.5 10.7 | 25.5 77.9 265 1 1 14.5 8.0
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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