Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
557
UXUS97 KGJT 211307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, June 21, 2024
This forecast is for Friday, June 21, 2024:
If the trigger temperature of 75.5 F/24.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 453 ft/min (2.3 m/s)
Maximum height of thermals.................. 13495 ft MSL (8656 ft AGL)
Forecast maximum temperature................... 86.0 F/30.5 C
Time of trigger temperature.................... 1030 MDT
Time of overdevelopment........................ None
Middle/high clouds during soaring window....... Broken/overcast thin middle
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 11744 ft MSL (6904 ft AGL)
Thermal soaring outlook for Saturday 06/22..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:48:32 / 20:43:42 MDT
Total possible sunshine........... 14 hr 55 min 10 sec (895 min 10 sec)
Altitude of sun at 13:16:07 MDT... 73.95 degrees
Upper air data from rawinsonde observation taken on 06/21/2024 at 0600 MDT
Freezing level.................. 15512 ft MSL (10673 ft AGL)
Convective condensation level... 13684 ft MSL (8845 ft AGL)
Lifted condensation level....... 13777 ft MSL (8937 ft AGL)
Lifted index.................... -3.4
K index......................... +23.7
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 -63.0 -81.4 240 83 43 -2.8 -1.5 88.5 191.2 34.0 M M
45000 -58.6 -73.5 230 99 51 0.3 0.2 71.4 160.5 25.8 M M
40000 -48.6 -55.5 225 103 53 6.1 3.3 64.2 147.5 22.8 M M
38000 -45.1 -49.2 220 98 51 7.8 4.3 60.7 141.2 21.0 M M
36000 -41.7 -43.1 215 92 48 7.2 4.0 57.2 134.9 19.0 M M
34000 -37.9 -36.2 210 68 35 4.4 2.4 53.2 127.8 16.7 M M
32000 -34.5 -30.1 215 55 28 6.8 3.7 49.9 121.8 14.6 M M
30000 -29.9 -21.8 225 52 27 8.0 4.4 48.4 119.0 13.8 M M
29000 -27.5 -17.5 230 54 28 7.6 4.2 47.6 117.7 13.4 M M
28000 -25.3 -13.5 220 51 26 7.1 3.9 46.7 116.1 12.8 M M
27000 -24.3 -11.7 200 36 19 3.7 2.0 44.2 111.5 11.0 M M
26000 -22.7 -8.9 200 36 19 10.4 5.7 42.6 108.7 9.9 M M
25000 -20.9 -5.6 225 28 14 5.7 3.1 41.3 106.3 8.8 M M
24000 -19.3 -2.7 235 32 16 8.9 4.9 39.5 103.1 7.6 M M
23000 -16.4 2.5 235 29 15 10.7 5.9 39.6 103.4 7.6 M M
22000 -14.7 5.5 235 28 14 4.2 2.3 38.3 100.9 6.5 M M
21000 -13.0 8.6 245 30 15 7.2 4.0 36.8 98.3 5.4 M M
20000 -10.7 12.7 240 33 17 6.3 3.5 36.0 96.7 4.7 M M
19500 -10.0 14.0 240 32 16 4.8 2.7 35.2 95.3 4.0 M M
19000 -9.0 15.8 235 27 14 10.1 5.5 34.7 94.4 3.6 M M
18500 -7.1 19.2 240 24 12 8.4 4.6 34.5 94.0 3.4 M M
18000 -5.8 21.6 235 24 12 8.3 4.6 34.2 93.6 3.2 M M
17500 -4.6 23.7 230 20 11 8.3 4.6 34.0 93.1 3.0 M M
17000 -3.4 25.9 225 16 8 8.3 4.6 33.7 92.6 2.7 M M
16500 -2.1 28.2 215 11 6 8.3 4.6 33.5 92.2 2.5 M M
16000 -0.9 30.4 195 10 5 8.2 4.5 33.2 91.8 2.3 M M
15500 0.2 32.4 190 11 5 8.1 4.4 32.9 91.2 2.0 M M
15000 1.4 34.5 195 13 6 8.0 4.4 32.7 90.9 1.8 M M
14500 2.3 36.1 195 17 9 4.9 2.7 32.1 89.8 1.2 M M
14000 3.0 37.4 205 16 8 4.7 2.6 31.3 88.4 0.5 M M
13500 4.0 39.2 210 15 8 9.1 5.0 30.9 87.5 -0.0 649 3.3
13000 5.3 41.5 205 15 8 8.8 4.8 30.7 87.2 -0.2 596 3.0
12500 6.4 43.5 205 16 8 10.4 5.7 30.4 86.8 -0.5 547 2.8
12000 6.3 43.3 205 8 4 -8.4 -4.6 28.9 83.9 -2.1 535 2.7
11500 6.4 43.5 195 8 4 5.4 3.0 27.5 81.4 -3.5 517 2.6
11000 7.2 45.0 185 10 5 5.9 3.3 26.7 80.1 -4.2 480 2.4
10500 8.1 46.6 205 10 5 7.6 4.2 26.2 79.2 -4.7 437 2.2
10250 8.7 47.7 215 9 5 8.4 4.6 26.1 79.0 -4.9 412 2.1
10000 9.3 48.7 220 8 4 8.3 4.5 26.0 78.9 -5.0 386 2.0
9750 9.9 49.8 215 9 5 8.3 4.6 25.9 78.7 -5.1 361 1.8
9500 10.5 50.9 215 10 5 8.3 4.5 25.8 78.5 -5.3 335 1.7
9250 11.1 52.0 210 12 6 8.3 4.6 25.7 78.3 -5.4 310 1.6
9000 11.7 53.1 210 13 7 8.3 4.6 25.6 78.1 -5.5 284 1.4
8750 12.3 54.1 210 13 7 8.3 4.6 25.5 77.9 -5.7 259 1.3
8500 12.9 55.2 205 13 7 8.3 4.6 25.4 77.7 -5.8 233 1.2
8250 13.5 56.3 210 15 8 8.3 4.6 25.3 77.5 -5.9 208 1.1
8000 14.2 57.6 210 18 9 8.3 4.6 25.2 77.3 -6.1 182 0.9
7750 14.8 58.6 205 17 9 8.3 4.6 25.1 77.1 -6.2 157 0.8
7500 15.4 59.7 195 17 9 8.3 4.6 24.9 76.9 -6.4 131 0.7
7250 16.0 60.8 190 18 9 8.3 4.6 24.8 76.7 -6.5 106 0.5
7000 16.6 61.9 180 19 10 8.3 4.6 24.7 76.5 -6.6 80 0.4
6750 17.2 63.0 180 20 10 8.3 4.6 24.6 76.3 -6.8 55 0.3
6500 17.8 64.0 170 23 12 8.3 4.5 24.5 76.0 -6.9 29 0.1
6250 18.4 65.1 165 26 13 8.5 4.7 24.4 75.8 -7.1 4 0.0
6000 18.9 66.0 160 29 15 3.3 1.8 24.1 75.4 -7.4 M M
5750 18.8 65.8 160 29 15 -3.3 -1.8 23.3 74.0 -8.2 M M
5500 18.6 65.5 165 29 15 1.1 0.6 22.4 72.4 -9.1 M M
5250 18.9 66.0 170 28 14 5.0 2.7 22.0 71.6 -9.6 M M
5000 19.1 66.4 175 26 14 1.6 0.9 21.5 70.7 -10.1 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/21/2024 at 0900 MDT | 06/21/2024 at 1200 MDT
|
CAPE... +447.6 LI... -3.4 | CAPE... +880.7 LI... -4.4
CINH... -79.5 K Index... +32.0 | CINH... -52.3 K Index... +32.4
|
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 -61.7 -79.1 225 64 33 1.8 1.0 | -61.8 -79.2 235 68 35 2.1 1.2
45000 -56.9 -70.4 235 92 47 6.1 3.3 | -56.7 -70.1 235 91 47 5.9 3.3
40000 -47.9 -54.2 230 98 51 5.0 2.7 | -48.1 -54.6 230 97 50 4.5 2.5
38000 -44.6 -48.3 225 87 45 4.9 2.7 | -45.0 -49.0 230 84 43 4.5 2.5
36000 -41.6 -42.9 220 78 40 4.9 2.7 | -42.3 -44.1 225 73 38 4.5 2.5
34000 -38.2 -36.8 220 69 36 5.9 3.2 | -38.6 -37.5 225 63 33 6.4 3.5
32000 -34.7 -30.5 220 60 31 5.7 3.1 | -34.8 -30.6 225 54 28 6.2 3.4
30000 -30.7 -23.3 220 54 28 6.9 3.8 | -30.4 -22.7 225 48 25 7.6 4.1
29000 -28.7 -19.7 220 52 27 6.9 3.8 | -28.2 -18.8 225 46 24 7.6 4.2
28000 -26.6 -15.9 220 49 25 7.1 3.9 | -25.9 -14.6 225 43 22 7.3 4.0
27000 -24.5 -12.1 220 47 24 7.3 4.0 | -23.9 -11.0 225 42 21 6.9 3.8
26000 -22.3 -8.1 220 44 23 7.3 4.0 | -21.9 -7.4 225 40 21 6.9 3.8
25000 -20.1 -4.2 220 42 21 7.4 4.1 | -19.9 -3.8 225 38 20 7.0 3.9
24000 -18.2 -0.8 220 39 20 6.4 3.5 | -17.5 0.5 225 36 19 6.4 3.5
23000 -15.8 3.6 225 36 19 6.5 3.6 | -15.6 3.9 225 35 18 6.4 3.5
22000 -13.9 7.0 225 33 17 6.4 3.5 | -13.7 7.3 225 33 17 6.4 3.5
21000 -12.1 10.2 225 32 16 6.2 3.4 | -11.8 10.8 230 32 16 6.4 3.5
20000 -10.3 13.5 230 30 16 6.2 3.4 | -10.0 14.0 230 31 16 6.4 3.5
19500 -9.3 15.3 230 29 15 6.2 3.4 | -9.0 15.8 230 30 16 6.4 3.5
19000 -8.4 16.9 230 29 15 6.5 3.6 | -8.1 17.4 230 30 15 6.3 3.4
18500 -7.5 18.5 230 28 14 6.5 3.6 | -7.2 19.0 230 29 15 6.3 3.5
18000 -6.5 20.3 235 27 14 6.9 3.8 | -6.3 20.7 230 29 15 6.4 3.5
17500 -5.5 22.1 230 26 13 7.2 3.9 | -5.4 22.3 230 28 15 6.5 3.6
17000 -4.5 23.9 230 25 13 7.2 4.0 | -4.4 24.1 230 28 14 6.5 3.6
16500 -3.4 25.9 230 24 12 7.6 4.2 | -3.4 25.9 230 27 14 6.9 3.8
16000 -2.3 27.9 230 23 12 7.6 4.2 | -2.5 27.5 230 27 14 6.9 3.8
15500 -1.2 29.8 230 22 11 7.8 4.3 | -1.5 29.3 225 26 13 7.0 3.9
15000 -0.1 31.8 225 22 11 7.9 4.3 | -0.5 31.1 225 25 13 7.1 3.9
14500 1.0 33.8 225 21 11 8.2 4.5 | 0.6 33.1 225 24 13 7.6 4.2
14000 2.3 36.1 225 21 11 8.5 4.6 | 1.7 35.1 225 23 12 8.1 4.5
13500 3.5 38.3 220 20 11 8.5 4.7 | 2.9 37.2 220 22 12 8.4 4.6
13000 4.7 40.5 220 20 10 8.6 4.7 | 4.3 39.7 220 21 11 9.2 5.1
12500 5.9 42.6 220 20 10 8.5 4.7 | 5.6 42.1 220 20 10 9.2 5.0
12000 7.1 44.8 215 20 10 8.2 4.5 | 6.9 44.4 220 19 10 8.6 4.7
11500 8.3 46.9 215 20 10 8.3 4.5 | 8.1 46.6 215 18 9 8.6 4.7
11000 9.4 48.9 210 20 10 7.1 3.9 | 9.3 48.7 215 17 9 7.8 4.3
10500 10.4 50.7 205 19 10 6.3 3.5 | 10.4 50.7 215 15 8 7.4 4.0
10250 10.8 51.4 210 19 10 4.9 2.7 | 10.9 51.6 215 15 8 7.6 4.2
10000 11.2 52.2 205 19 10 6.2 3.4 | 11.5 52.7 215 15 7 8.5 4.7
9750 11.7 53.1 200 18 9 7.0 3.8 | 12.1 53.8 210 14 7 8.3 4.5
9500 12.1 53.8 195 18 9 6.7 3.7 | 12.6 54.7 210 13 7 8.4 4.6
9250 12.6 54.7 195 18 9 6.0 3.3 | 13.2 55.8 205 13 7 8.6 4.7
9000 13.0 55.4 195 18 9 5.3 2.9 | 13.8 56.8 205 12 6 7.8 4.3
8750 13.4 56.1 190 18 9 5.3 2.9 | 14.3 57.7 205 12 6 7.2 3.9
8500 13.7 56.7 185 17 9 5.0 2.7 | 15.3 59.5 200 11 6 6.0 3.3
8250 14.1 57.4 180 17 9 3.7 2.0 | 15.8 60.4 195 11 6 6.9 3.8
8000 14.6 58.3 170 17 9 5.0 2.7 | 16.4 61.5 190 10 5 9.3 5.1
7750 14.9 58.8 165 16 8 3.3 1.8 | 17.0 62.6 185 10 5 7.8 4.3
7500 15.0 59.0 160 15 8 0.6 0.3 | 17.5 63.5 180 10 5 5.1 2.8
7250 15.1 59.2 155 15 8 1.0 0.5 | 17.8 64.0 175 9 5 5.5 3.0
7000 15.3 59.5 150 14 7 6.1 3.4 | 18.4 65.1 170 9 5 10.5 5.8
6750 15.8 60.4 150 12 6 7.7 4.2 | 19.2 66.6 170 8 4 9.1 5.0
6500 16.3 61.3 145 12 6 5.7 3.1 | 19.6 67.3 165 7 4 5.3 2.9
6250 16.7 62.1 145 11 6 6.0 3.3 | 20.0 68.0 160 6 3 5.9 3.2
6000 17.2 63.0 145 11 5 9.0 4.9 | 20.5 68.9 155 5 3 9.3 5.1
5750 18.1 64.6 140 8 4 14.5 8.0 | 21.4 70.5 155 5 2 17.8 9.8
5500 18.7 65.7 135 8 4 -1.3 -0.7 | 22.4 72.3 140 3 2 4.8 2.6
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
06/21/2024 at 1500 MDT | 06/21/2024 at 1800 MDT
|
CAPE... +1179.3 LI... -4.9 | CAPE... +1222.4 LI... -4.3
CINH... -22.0 K Index... +31.9 | CINH... -59.5 K Index... +25.0
|
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 -62.2 -80.0 235 73 37 2.0 1.1 | -61.9 -79.4 245 72 37 1.5 0.8
45000 -57.4 -71.3 240 90 46 5.6 3.1 | -57.6 -71.7 240 89 46 5.6 3.1
40000 -48.5 -55.3 235 92 47 5.7 3.2 | -48.7 -55.7 230 86 45 6.2 3.4
38000 -45.0 -49.0 235 80 41 5.7 3.2 | -44.9 -48.8 230 78 40 6.2 3.4
36000 -41.6 -42.9 230 69 35 5.9 3.3 | -41.2 -42.2 230 69 36 6.4 3.5
34000 -37.6 -35.7 230 60 31 6.7 3.7 | -37.1 -34.8 230 64 33 6.9 3.8
32000 -33.5 -28.3 225 51 26 6.5 3.6 | -33.0 -27.4 230 60 31 6.7 3.7
30000 -29.3 -20.7 225 48 25 7.1 3.9 | -28.7 -19.7 235 58 30 7.3 4.0
29000 -27.2 -17.0 225 48 25 7.1 3.9 | -26.5 -15.7 235 57 30 7.3 4.0
28000 -25.0 -13.0 225 47 24 7.2 4.0 | -24.3 -11.7 235 57 29 7.2 3.9
27000 -22.9 -9.2 225 46 24 7.3 4.0 | -22.2 -8.0 235 55 28 7.0 3.9
26000 -20.7 -5.3 225 45 23 7.3 4.0 | -20.1 -4.2 235 52 27 7.1 3.9
25000 -18.5 -1.3 220 43 22 7.5 4.1 | -18.1 -0.6 240 50 26 7.2 4.0
24000 -16.2 2.8 220 41 21 6.2 3.4 | -15.7 3.7 240 47 24 6.3 3.4
23000 -14.4 6.1 225 39 20 6.3 3.4 | -13.9 7.0 240 44 23 6.3 3.5
22000 -12.5 9.5 225 37 19 6.1 3.4 | -12.1 10.2 240 42 22 5.9 3.2
21000 -10.8 12.6 225 35 18 6.0 3.3 | -10.4 13.3 240 39 20 5.5 3.0
20000 -9.0 15.8 230 33 17 6.0 3.3 | -8.8 16.2 245 37 19 5.5 3.0
19500 -8.2 17.2 230 33 17 6.0 3.3 | -8.0 17.6 245 35 18 5.4 3.0
19000 -7.3 18.9 230 32 17 6.0 3.3 | -7.1 19.2 245 34 18 6.9 3.8
18500 -6.4 20.5 230 32 16 6.0 3.3 | -6.1 21.0 245 33 17 6.8 3.7
18000 -5.6 21.9 230 31 16 6.3 3.4 | -5.1 22.8 245 31 16 6.9 3.8
17500 -4.6 23.7 230 30 16 6.5 3.5 | -4.0 24.8 245 30 15 7.0 3.9
17000 -3.7 25.3 230 30 15 6.5 3.6 | -3.0 26.6 245 28 15 7.0 3.9
16500 -2.7 27.1 230 29 15 7.4 4.1 | -1.9 28.6 245 27 14 7.7 4.2
16000 -1.6 29.1 230 28 14 7.3 4.0 | -0.8 30.6 245 26 13 7.6 4.2
15500 -0.6 30.9 230 27 14 7.7 4.2 | 0.4 32.7 245 25 13 7.7 4.2
15000 0.5 32.9 230 26 13 7.8 4.3 | 1.5 34.7 245 24 13 7.7 4.3
14500 1.7 35.1 225 25 13 7.9 4.3 | 2.6 36.7 245 24 12 7.9 4.3
14000 2.8 37.0 225 24 12 8.1 4.4 | 3.7 38.7 245 22 12 8.2 4.5
13500 4.0 39.2 225 22 11 8.2 4.5 | 4.9 40.8 245 21 11 8.2 4.5
13000 5.2 41.4 225 21 11 8.6 4.7 | 6.0 42.8 240 19 10 8.3 4.6
12500 6.4 43.5 220 20 10 8.6 4.7 | 7.2 45.0 240 18 9 8.4 4.6
12000 7.7 45.9 220 18 10 8.4 4.6 | 8.4 47.1 235 16 8 8.6 4.7
11500 8.9 48.0 220 17 9 8.4 4.6 | 9.6 49.3 230 15 8 8.7 4.8
11000 10.0 50.0 220 16 8 7.9 4.3 | 10.8 51.4 225 14 7 7.6 4.2
10500 11.2 52.2 215 14 7 4.7 2.6 | 11.8 53.2 220 13 6 8.2 4.5
10250 11.3 52.3 215 13 7 5.3 2.9 | 12.5 54.5 215 12 6 8.2 4.5
10000 12.0 53.6 215 12 6 10.3 5.6 | 13.0 55.4 210 12 6 7.2 4.0
9750 12.7 54.9 215 12 6 8.9 4.9 | 13.5 56.3 205 12 6 7.3 4.0
9500 13.3 55.9 215 11 6 9.3 5.1 | 14.0 57.2 205 11 6 7.0 3.8
9250 13.9 57.0 215 11 6 7.0 3.9 | 14.6 58.3 200 11 6 8.2 4.5
9000 14.4 57.9 215 9 5 7.3 4.0 | 15.1 59.2 195 10 5 7.8 4.3
8750 15.0 59.0 215 9 5 9.2 5.0 | 16.1 61.0 185 10 5 6.8 3.7
8500 15.6 60.1 215 9 5 8.5 4.7 | 16.5 61.7 185 10 5 5.4 2.9
8250 16.6 61.9 220 8 4 7.2 3.9 | 16.8 62.2 180 9 5 5.8 3.2
8000 17.2 63.0 220 7 4 10.3 5.6 | 17.3 63.1 175 9 5 7.7 4.2
7750 17.9 64.2 220 7 4 8.6 4.7 | 17.9 64.2 170 9 5 7.1 3.9
7500 18.4 65.1 220 7 3 5.2 2.9 | 18.3 64.9 170 9 5 4.9 2.7
7250 18.7 65.7 225 6 3 5.4 3.0 | 18.6 65.5 160 9 5 4.6 2.5
7000 19.2 66.6 225 6 3 11.7 6.4 | 19.0 66.2 160 9 5 8.2 4.5
6750 20.2 68.4 225 5 3 10.3 5.6 | 19.7 67.5 160 9 4 8.5 4.7
6500 20.6 69.1 225 5 3 5.7 3.1 | 20.1 68.2 155 8 4 6.8 3.7
6250 21.1 70.0 230 5 2 6.3 3.5 | 20.6 69.1 155 8 4 6.5 3.6
6000 21.6 70.9 230 4 2 10.5 5.7 | 21.1 70.0 155 8 4 10.4 5.7
5750 22.7 72.9 230 4 2 19.2 10.5 | 22.1 71.8 150 7 3 17.6 9.6
5500 23.7 74.7 230 3 2 1.8 1.0 | 22.9 73.2 150 6 3 1.3 0.7
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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