Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 251306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Wednesday, September 25, 2024
This forecast is for Wednesday, September 25, 2024:
If the trigger temperature of 80.5 F/27.0 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 576 ft/min (2.9 m/s)
Maximum height of thermals.................. 12436 ft MSL (7597 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1230 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................. 9994 ft MSL (5155 ft AGL)
Thermal soaring outlook for Thursday 09/26..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:05:24 / 19:05:43 MDT
Total possible sunshine........... 12 hr 0 min 19 sec (720 min 19 sec)
Altitude of sun at 13:05:33 MDT... 49.59 degrees
Upper air data from rawinsonde observation taken on 09/25/2024 at 0600 MDT
Freezing level.................. 16883 ft MSL (12044 ft AGL)
Convective condensation level... 20208 ft MSL (15369 ft AGL)
Lifted condensation level....... 16858 ft MSL (12019 ft AGL)
Lifted index.................... +4.8
K index......................... +8.7
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 -66.3 -87.3 180 12 6 -2.4 -1.3 83.3 182.0 30.3 M M
45000 -61.9 -79.4 220 13 7 3.7 2.0 66.2 151.2 21.9 M M
40000 -54.7 -66.5 145 17 9 8.0 4.4 54.5 130.2 15.6 M M
38000 -49.8 -57.6 150 21 11 7.9 4.3 53.1 127.6 15.1 M M
36000 -45.1 -49.2 155 15 8 7.9 4.3 51.5 124.7 14.3 M M
34000 -39.5 -39.1 150 12 6 8.5 4.7 50.1 122.2 13.7 M M
32000 -34.3 -29.7 145 9 5 8.9 4.9 49.2 120.6 13.4 M M
30000 -29.5 -21.1 155 12 6 6.7 3.7 47.9 118.2 12.7 M M
29000 -26.9 -16.4 160 14 7 9.1 5.0 47.5 117.5 12.6 M M
28000 -24.1 -11.4 180 16 8 9.1 5.0 47.2 117.0 12.5 M M
27000 -21.4 -6.5 175 15 8 9.0 5.0 47.0 116.6 12.5 M M
26000 -18.7 -1.7 180 17 9 9.0 5.0 46.7 116.1 12.4 M M
25000 -16.0 3.2 175 13 7 8.7 4.8 46.4 115.5 12.3 M M
24000 -13.9 7.0 170 11 6 6.8 3.7 45.5 113.8 11.7 M M
23000 -11.8 10.8 195 7 3 6.8 3.8 44.4 111.9 10.9 M M
22000 -9.9 14.2 205 4 2 6.3 3.5 43.2 109.8 10.0 M M
21000 -8.0 17.6 205 2 1 6.4 3.5 42.0 107.6 9.1 M M
20000 -6.1 21.0 175 8 4 7.6 4.2 40.8 105.5 8.1 M M
19500 -4.8 23.4 170 9 5 8.9 4.9 40.7 105.2 8.0 M M
19000 -2.7 27.1 155 11 6 8.3 4.5 40.5 104.9 8.0 M M
18500 -2.6 27.3 140 17 9 -1.5 -0.9 39.0 102.2 6.7 M M
18000 -2.2 28.0 150 12 6 4.7 2.6 37.8 100.1 5.6 M M
17500 -1.2 29.8 150 12 6 7.7 4.2 37.3 99.1 5.2 M M
17000 -0.1 31.8 160 16 8 8.0 4.4 37.0 98.5 4.9 M M
16500 1.1 34.0 170 14 7 8.2 4.5 36.6 98.0 4.6 M M
16000 2.1 35.8 165 12 6 5.5 3.0 36.2 97.1 4.2 M M
15500 2.9 37.2 160 15 8 5.6 3.1 35.5 95.8 3.5 M M
15000 3.7 38.7 160 16 8 5.6 3.1 34.8 94.6 2.9 M M
14500 4.5 40.1 160 12 6 7.7 4.2 34.1 93.4 2.3 M M
14000 5.9 42.6 190 8 4 8.3 4.6 34.0 93.2 2.2 M M
13500 6.8 44.2 195 12 6 5.5 3.0 33.5 92.3 1.6 M M
13000 7.6 45.7 185 18 9 4.9 2.7 32.8 91.0 1.0 M M
12500 8.2 46.8 190 16 8 4.4 2.4 31.9 89.4 0.1 M M
12000 8.7 47.7 215 13 7 4.0 2.2 30.9 87.7 -0.9 548 2.8
11500 9.7 49.5 210 15 8 8.9 4.9 30.5 86.9 -1.3 503 2.6
11000 10.6 51.1 185 14 7 5.0 2.7 30.0 86.0 -1.9 460 2.3
10500 11.4 52.5 165 15 8 6.6 3.6 29.4 84.8 -2.6 422 2.1
10250 11.9 53.4 160 15 8 6.9 3.8 29.1 84.4 -2.8 399 2.0
10000 12.5 54.5 160 15 8 6.7 3.7 28.9 84.0 -3.0 376 1.9
9750 13.0 55.4 160 9 5 6.8 3.7 28.7 83.6 -3.2 352 1.8
9500 13.5 56.3 160 9 5 6.8 3.7 28.4 83.2 -3.4 329 1.7
9250 14.0 57.2 155 9 5 6.8 3.7 28.2 82.8 -3.6 306 1.6
9000 14.6 58.3 150 5 3 6.8 3.7 28.0 82.4 -3.8 283 1.4
8750 15.1 59.2 155 8 4 6.8 3.7 27.7 81.9 -4.0 260 1.3
8500 15.6 60.1 160 11 6 6.7 3.7 27.5 81.5 -4.2 236 1.2
8250 16.1 61.0 155 11 6 6.0 3.3 27.3 81.1 -4.5 215 1.1
8000 16.5 61.7 155 12 6 5.4 3.0 26.9 80.5 -4.9 196 1.0
7750 16.9 62.4 155 12 6 6.5 3.5 26.6 79.9 -5.2 176 0.9
7500 17.3 63.1 155 12 6 3.6 2.0 26.3 79.4 -5.5 155 0.8
7250 17.5 63.5 145 11 6 4.0 2.2 25.8 78.4 -6.1 144 0.7
7000 17.9 64.2 135 11 6 7.0 3.8 25.5 77.9 -6.4 123 0.6
6750 18.4 65.1 130 11 5 6.9 3.8 25.3 77.5 -6.7 102 0.5
6500 18.8 65.8 120 10 5 0.3 0.1 24.9 76.8 -7.1 83 0.4
6250 18.4 65.1 120 10 5 -5.5 -3.0 23.8 74.9 -8.1 86 0.4
6000 18.1 64.6 135 15 8 -4.2 -2.3 22.8 73.0 -9.2 89 0.5
5750 17.8 64.0 135 16 8 0.5 0.3 21.8 71.3 -10.2 89 0.5
5500 18.0 64.4 135 17 9 3.3 1.8 21.3 70.4 -10.8 75 0.4
5250 18.0 64.4 130 16 8 -5.4 -3.0 20.5 69.0 -11.6 70 0.4
5000 17.1 62.8 130 18 9 -19.1 -10.5 18.9 66.0 -13.2 88 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
09/25/2024 at 0900 MDT | 09/25/2024 at 1200 MDT
|
CAPE... 0.0 LI... +6.6 | CAPE... 0.0 LI... +6.3
CINH... -0.1 K Index... +6.2 | CINH... -0.1 K Index... +7.9
|
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 -66.3 -87.3 225 10 5 2.6 1.4 | -66.5 -87.7 220 17 9 2.1 1.2
45000 -61.3 -78.3 205 14 7 4.9 2.7 | -61.8 -79.2 205 20 10 5.1 2.8
40000 -53.6 -64.5 175 18 9 7.2 4.0 | -53.7 -64.7 175 23 12 7.4 4.0
38000 -48.7 -55.7 170 21 11 7.2 4.0 | -48.7 -55.7 180 27 14 7.4 4.1
36000 -44.3 -47.7 170 24 13 7.9 4.3 | -44.3 -47.7 180 30 15 7.9 4.4
34000 -39.3 -38.7 165 20 11 8.4 4.6 | -39.3 -38.7 175 27 14 8.4 4.6
32000 -34.3 -29.7 160 17 9 8.5 4.7 | -34.2 -29.6 170 23 12 8.5 4.7
30000 -29.3 -20.7 155 16 8 8.4 4.6 | -29.2 -20.6 165 21 11 8.3 4.6
29000 -26.8 -16.2 155 15 8 8.4 4.6 | -26.8 -16.2 165 20 10 8.3 4.6
28000 -24.2 -11.6 155 15 8 8.5 4.7 | -24.3 -11.7 165 19 10 8.4 4.6
27000 -21.7 -7.1 165 15 8 8.5 4.7 | -21.7 -7.1 175 17 9 8.4 4.6
26000 -19.2 -2.6 170 15 8 8.5 4.7 | -19.2 -2.6 180 17 9 8.4 4.6
25000 -16.6 2.1 180 15 8 8.1 4.5 | -16.7 1.9 190 16 8 8.1 4.4
24000 -14.5 5.9 185 14 7 6.9 3.8 | -14.6 5.7 195 15 7 6.9 3.8
23000 -12.0 10.4 190 12 6 6.9 3.8 | -12.0 10.4 205 12 6 7.0 3.8
22000 -9.9 14.2 195 11 6 6.9 3.8 | -10.0 14.0 210 11 6 6.9 3.8
21000 -7.9 17.8 190 11 5 6.9 3.8 | -7.9 17.8 205 11 6 6.9 3.8
20000 -5.9 21.4 185 11 5 6.9 3.8 | -5.9 21.4 200 12 6 6.9 3.8
19500 -4.8 23.4 180 11 5 6.9 3.8 | -4.9 23.2 200 12 6 6.9 3.8
19000 -3.8 25.2 180 11 5 6.8 3.7 | -3.9 25.0 195 12 6 6.9 3.8
18500 -2.8 27.0 175 11 6 6.8 3.7 | -2.9 26.8 195 13 7 7.0 3.8
18000 -1.9 28.6 175 11 6 6.4 3.5 | -1.9 28.6 195 13 7 6.1 3.3
17500 -0.9 30.4 180 11 6 6.3 3.5 | -1.0 30.2 195 14 7 6.0 3.3
17000 -0.0 32.0 180 11 6 6.2 3.4 | -0.2 31.6 195 14 7 5.9 3.2
16500 0.8 33.4 185 11 6 5.4 3.0 | 0.7 33.3 195 14 7 5.7 3.1
16000 1.6 34.9 190 11 6 5.5 3.0 | 1.5 34.7 195 15 8 5.8 3.2
15500 2.4 36.3 195 12 6 5.3 2.9 | 2.3 36.1 200 15 8 5.6 3.0
15000 3.1 37.6 200 12 6 5.3 2.9 | 3.1 37.6 200 15 8 5.6 3.1
14500 3.9 39.0 205 13 6 5.5 3.0 | 3.9 39.0 200 15 8 5.5 3.0
14000 4.7 40.5 210 13 7 5.7 3.1 | 4.7 40.5 200 15 8 5.5 3.0
13500 5.5 41.9 210 14 7 5.9 3.2 | 5.4 41.7 205 15 8 5.7 3.1
13000 6.4 43.5 215 14 7 6.3 3.4 | 6.3 43.3 205 15 8 6.2 3.4
12500 7.3 45.1 215 14 7 6.3 3.5 | 7.2 45.0 210 15 8 6.3 3.5
12000 8.3 46.9 215 14 7 6.6 3.6 | 8.2 46.8 210 14 7 6.8 3.7
11500 9.2 48.6 215 14 7 6.6 3.6 | 9.2 48.6 215 14 7 6.8 3.7
11000 10.2 50.4 215 13 7 6.6 3.6 | 10.3 50.5 215 13 7 7.3 4.0
10500 11.1 52.0 215 12 6 5.3 2.9 | 11.4 52.5 220 13 7 5.0 2.7
10250 11.4 52.5 215 11 6 4.5 2.5 | 11.6 52.9 220 12 6 5.6 3.1
10000 11.9 53.4 210 11 6 6.9 3.8 | 12.3 54.1 220 12 6 9.1 5.0
9750 12.4 54.3 210 11 6 7.5 4.1 | 12.9 55.2 220 11 6 8.2 4.5
9500 12.9 55.2 205 10 5 7.2 3.9 | 13.5 56.3 220 10 5 8.2 4.5
9250 13.4 56.1 200 10 5 6.3 3.4 | 14.0 57.2 220 9 5 7.0 3.9
9000 13.9 57.0 200 9 5 5.7 3.1 | 14.5 58.1 220 8 4 6.9 3.8
8750 14.3 57.7 195 9 5 6.0 3.3 | 15.1 59.2 215 8 4 7.5 4.1
8500 15.1 59.2 185 9 5 4.7 2.6 | 15.6 60.1 210 8 4 6.8 3.8
8250 15.5 59.9 180 9 5 4.5 2.5 | 16.0 60.8 205 7 4 4.8 2.6
8000 15.8 60.4 175 8 4 5.1 2.8 | 17.0 62.6 200 5 3 10.1 5.6
7750 16.2 61.2 170 8 4 4.4 2.4 | 17.7 63.9 195 5 3 8.3 4.5
7500 16.4 61.5 170 8 4 3.5 1.9 | 18.2 64.8 195 5 2 5.5 3.0
7250 16.7 62.1 165 8 4 3.4 1.9 | 18.6 65.5 190 4 2 7.0 3.8
7000 16.9 62.4 160 7 4 2.5 1.4 | 19.3 66.7 190 3 2 12.8 7.0
6750 17.0 62.6 155 7 3 1.5 0.8 | 20.4 68.7 190 4 2 12.1 6.6
6500 17.1 62.8 150 6 3 1.5 0.8 | 21.1 70.0 190 3 2 8.9 4.9
6250 17.2 63.0 145 6 3 1.3 0.7 | 21.8 71.2 185 3 1 8.8 4.8
6000 17.4 63.3 135 6 3 3.4 1.9 | 22.5 72.5 185 2 1 13.5 7.4
5750 17.8 64.0 120 4 2 6.9 3.8 | 24.0 75.2 190 3 1 25.9 14.2
5500 18.0 64.4 100 4 2 -3.4 -1.9 | 25.6 78.1 185 2 1 10.1 5.5
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
09/25/2024 at 1500 MDT | 09/25/2024 at 1800 MDT
|
CAPE... 0.0 LI... +5.0 | CAPE... 0.0 LI... +4.7
CINH... -0.1 K Index... +11.4 | CINH... 0.0 K Index... +11.2
|
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 -66.1 -87.0 230 21 11 2.6 1.4 | -65.7 -86.3 255 21 11 2.6 1.4
45000 -61.2 -78.2 210 24 12 4.7 2.6 | -60.6 -77.1 235 24 12 5.0 2.8
40000 -53.7 -64.7 180 28 15 7.0 3.8 | -52.9 -63.2 195 32 16 6.2 3.4
38000 -49.0 -56.2 185 32 16 7.0 3.9 | -48.7 -55.7 190 34 17 6.2 3.4
36000 -44.8 -48.6 185 35 18 7.8 4.3 | -45.0 -49.0 185 36 18 7.1 3.9
34000 -39.6 -39.3 180 33 17 8.6 4.7 | -40.0 -40.0 185 34 18 8.5 4.6
32000 -34.5 -30.1 180 31 16 8.7 4.8 | -34.9 -30.8 185 33 17 8.6 4.7
30000 -29.4 -20.9 175 28 14 8.4 4.6 | -29.8 -21.6 185 31 16 8.5 4.7
29000 -26.9 -16.4 175 26 14 8.4 4.6 | -27.2 -17.0 185 29 15 8.5 4.7
28000 -24.3 -11.7 175 25 13 8.4 4.6 | -24.7 -12.5 190 28 14 8.0 4.4
27000 -21.8 -7.2 180 23 12 8.5 4.6 | -22.3 -8.1 195 25 13 7.9 4.3
26000 -19.3 -2.7 185 21 11 8.5 4.6 | -19.9 -3.8 195 22 11 7.9 4.3
25000 -16.8 1.8 190 19 10 8.2 4.5 | -17.6 0.3 205 19 10 7.9 4.3
24000 -14.6 5.7 195 16 8 6.9 3.8 | -15.3 4.5 200 17 9 7.5 4.1
23000 -12.1 10.2 200 12 6 6.9 3.8 | -12.5 9.5 200 14 7 7.5 4.1
22000 -10.0 14.0 205 10 5 7.0 3.8 | -10.3 13.5 195 13 7 7.4 4.1
21000 -8.0 17.6 205 10 5 7.0 3.8 | -8.1 17.4 195 13 7 7.4 4.0
20000 -5.9 21.4 200 11 6 7.0 3.9 | -5.9 21.4 195 13 6 7.4 4.1
19500 -4.9 23.2 200 11 6 7.0 3.8 | -4.9 23.2 195 13 6 7.4 4.1
19000 -3.8 25.2 200 12 6 6.9 3.8 | -3.8 25.2 195 13 7 7.4 4.0
18500 -2.8 27.0 200 12 6 6.9 3.8 | -2.7 27.1 195 13 7 7.4 4.1
18000 -1.8 28.8 200 13 7 6.6 3.6 | -1.6 29.1 200 14 7 6.8 3.7
17500 -0.9 30.4 200 14 7 6.5 3.6 | -0.6 30.9 200 15 8 6.7 3.7
17000 0.1 32.2 200 14 7 6.3 3.4 | 0.3 32.5 200 15 8 6.5 3.5
16500 0.8 33.4 200 15 8 5.0 2.7 | 1.2 34.2 200 16 8 5.3 2.9
16000 1.6 34.9 200 16 8 5.1 2.8 | 1.9 35.4 200 16 8 5.4 3.0
15500 2.3 36.1 195 16 8 5.1 2.8 | 2.6 36.7 195 17 9 4.8 2.6
15000 3.0 37.4 195 17 9 5.1 2.8 | 3.3 37.9 200 17 9 4.9 2.7
14500 3.7 38.7 195 17 9 5.7 3.1 | 4.0 39.2 200 17 9 5.7 3.1
14000 4.6 40.3 195 16 8 6.1 3.3 | 4.9 40.8 200 16 8 6.3 3.5
13500 5.5 41.9 200 16 8 6.5 3.6 | 5.7 42.3 200 15 8 6.9 3.8
13000 6.5 43.7 200 15 8 7.4 4.1 | 6.9 44.4 200 13 7 8.3 4.5
12500 7.6 45.7 200 14 7 7.5 4.1 | 8.1 46.6 200 12 6 8.3 4.5
12000 8.7 47.7 200 13 7 8.4 4.6 | 9.3 48.7 200 11 6 8.6 4.7
11500 10.0 50.0 205 12 6 8.3 4.6 | 10.6 51.1 200 10 5 8.6 4.7
11000 11.1 52.0 205 10 5 7.5 4.1 | 11.8 53.2 200 9 4 7.5 4.1
10500 12.2 54.0 210 9 4 9.9 5.4 | 12.9 55.2 205 7 4 9.6 5.3
10250 13.1 55.6 210 8 4 10.5 5.8 | 13.7 56.7 210 7 3 10.1 5.5
10000 13.7 56.7 215 8 4 7.8 4.3 | 14.4 57.9 215 6 3 7.8 4.3
9750 14.3 57.7 215 7 4 8.6 4.7 | 15.0 59.0 215 6 3 8.4 4.6
9500 14.9 58.8 220 6 3 8.1 4.4 | 15.6 60.1 225 5 3 8.3 4.5
9250 15.5 59.9 225 5 3 7.2 4.0 | 16.2 61.2 230 4 2 8.1 4.5
9000 16.1 61.0 235 4 2 8.2 4.5 | 16.8 62.2 240 4 2 8.3 4.6
8750 16.7 62.1 240 4 2 9.5 5.2 | 17.5 63.5 250 4 2 8.6 4.7
8500 18.0 64.4 255 4 2 6.1 3.4 | 18.7 65.7 270 3 2 6.8 3.7
8250 18.4 65.1 280 3 2 8.1 4.5 | 19.2 66.6 290 3 2 7.7 4.2
8000 19.3 66.7 275 4 2 12.3 6.7 | 19.9 67.8 290 4 2 9.9 5.4
7750 20.1 68.2 265 4 2 10.3 5.6 | 20.6 69.1 290 4 2 8.9 4.9
7500 20.8 69.4 275 4 2 7.5 4.1 | 21.2 70.2 295 4 2 6.9 3.8
7250 21.3 70.3 290 4 2 8.1 4.4 | 21.7 71.1 305 4 2 7.3 4.0
7000 22.1 71.8 290 4 2 12.9 7.1 | 22.3 72.1 305 5 2 11.0 6.0
6750 23.1 73.6 275 4 2 12.0 6.6 | 23.2 73.8 295 4 2 11.0 6.0
6500 23.8 74.8 285 4 2 9.1 5.0 | 23.9 75.0 300 5 2 9.1 5.0
6250 24.5 76.1 300 4 2 9.2 5.1 | 24.6 76.3 310 5 2 9.3 5.1
6000 25.3 77.5 305 4 2 12.0 6.6 | 25.3 77.5 310 5 2 9.1 5.0
5750 26.5 79.7 290 4 2 22.4 12.3 | 26.0 78.8 300 4 2 10.4 5.7
5500 28.4 83.1 310 5 2 24.5 13.4 | 27.0 80.6 315 4 2 16.6 9.1
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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