Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
421
UXUS97 KGJT 221307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Saturday, June 22, 2024
This forecast is for Saturday, June 22, 2024:
If the trigger temperature of 80.5 F/26.9 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1046 ft/min (5.3 m/s)
Maximum height of thermals.................. 16757 ft MSL (11918 ft AGL)
Forecast maximum temperature................... 91.0 F/33.2 C
Time of trigger temperature.................... 1045 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................. 11250 ft MSL (6411 ft AGL)
Thermal soaring outlook for Sunday 06/23....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:48:48 / 20:43:53 MDT
Total possible sunshine........... 14 hr 55 min 5 sec (895 min 5 sec)
Altitude of sun at 13:16:20 MDT... 73.93 degrees
Upper air data from rawinsonde observation taken on 06/22/2024 at 0600 MDT
Freezing level.................. 15546 ft MSL (10707 ft AGL)
Convective condensation level... 14087 ft MSL (9248 ft AGL)
Lifted condensation level....... 14908 ft MSL (10068 ft AGL)
Lifted index.................... -2.9
K index......................... +20.4
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 -62.6 -80.7 255 73 38 1.9 1.1 89.3 192.7 32.8 M M
45000 -57.5 -71.5 240 85 44 6.0 3.3 72.2 162.0 24.6 M M
40000 -48.3 -54.9 240 94 48 6.3 3.5 64.0 147.3 20.9 M M
38000 -44.4 -47.9 240 93 48 6.4 3.5 61.2 142.1 19.4 M M
36000 -41.0 -41.8 235 74 38 -2.0 -1.1 57.6 135.7 17.5 M M
34000 -37.8 -36.0 240 68 35 6.9 3.8 53.8 128.9 15.2 M M
32000 -33.3 -27.9 245 61 31 6.2 3.4 52.0 125.7 14.2 M M
30000 -28.6 -19.5 255 54 28 8.0 4.4 49.5 121.1 12.7 M M
29000 -26.4 -15.5 250 52 27 5.7 3.1 48.6 119.4 12.1 M M
28000 -24.6 -12.3 255 49 25 6.0 3.3 47.1 116.8 11.1 M M
27000 -22.8 -9.0 255 50 26 6.0 3.3 45.7 114.2 10.1 M M
26000 -21.0 -5.8 255 51 26 7.6 4.1 44.2 111.6 9.1 M M
25000 -18.4 -1.1 255 47 24 8.5 4.7 43.8 110.9 8.9 M M
24000 -16.3 2.7 260 42 22 6.2 3.4 42.9 109.2 8.2 M M
23000 -14.4 6.1 260 46 24 3.8 2.1 41.5 106.7 7.2 M M
22000 -14.2 6.4 255 42 22 2.5 1.4 38.3 100.9 4.5 M M
21000 -14.1 6.6 255 40 21 6.0 3.3 35.3 95.5 1.8 M M
20000 -11.8 10.8 265 39 20 9.0 4.9 34.5 94.2 1.1 M M
19500 -10.4 13.3 270 39 20 9.6 5.2 34.5 94.1 1.0 M M
19000 -9.1 15.6 270 37 19 7.2 4.0 34.3 93.8 0.9 M M
18500 -8.0 17.6 275 34 18 8.9 4.9 34.0 93.2 0.6 M M
18000 -6.7 19.9 280 32 16 8.7 4.8 33.8 92.8 0.4 M M
17500 -5.4 22.3 285 29 15 8.7 4.8 33.6 92.5 0.3 M M
17000 -4.1 24.6 290 27 14 8.7 4.8 33.5 92.3 0.1 M M
16500 -2.2 28.0 295 23 12 8.7 4.8 33.2 91.8 -0.1 1005 5.1
16000 -0.9 30.4 295 20 11 8.7 4.8 33.0 91.4 -0.3 952 4.8
15500 0.4 32.7 290 18 9 8.8 4.8 32.8 91.0 -0.5 899 4.6
15000 1.6 34.9 290 16 8 6.9 3.8 32.5 90.5 -0.8 848 4.3
14500 2.6 36.7 285 10 5 6.9 3.8 32.0 89.6 -1.2 803 4.1
14000 3.5 38.3 250 7 4 7.0 3.8 31.6 88.8 -1.8 760 3.9
13500 4.5 40.1 245 7 4 7.5 4.1 31.1 88.0 -2.2 715 3.6
13000 5.8 42.4 240 7 4 8.9 4.9 30.9 87.6 -2.5 663 3.4
12500 7.1 44.8 225 7 4 8.8 4.8 30.8 87.4 -2.6 609 3.1
12000 8.4 47.1 215 7 4 8.8 4.8 30.6 87.1 -2.8 555 2.8
11500 9.7 49.5 205 8 4 8.8 4.8 30.5 86.8 -2.9 501 2.5
11000 11.0 51.8 195 10 5 8.3 4.6 30.3 86.6 -3.1 446 2.3
10500 12.1 53.8 215 11 6 7.3 4.0 30.0 86.0 -3.5 400 2.0
10250 12.5 54.5 230 10 5 6.4 3.5 29.8 85.6 -3.8 379 1.9
10000 13.0 55.4 230 10 5 6.4 3.5 29.5 85.1 -4.1 359 1.8
9750 13.4 56.1 225 12 6 6.5 3.5 29.3 84.7 -4.4 339 1.7
9500 13.8 56.8 220 13 7 6.6 3.6 29.0 84.2 -4.7 319 1.6
9250 14.2 57.6 215 12 6 6.3 3.5 28.7 83.7 -5.1 299 1.5
9000 14.6 58.3 210 9 5 7.7 4.2 28.5 83.3 -5.4 279 1.4
8750 15.0 59.0 190 10 5 2.6 1.4 28.3 82.9 -5.7 260 1.3
8500 14.8 58.6 180 13 7 -8.4 -4.6 27.2 81.0 -6.7 260 1.3
8250 14.1 57.4 170 17 9 -7.1 -3.9 25.8 78.4 -8.1 273 1.4
8000 14.0 57.2 165 20 11 2.1 1.2 24.8 76.7 -9.0 270 1.4
7750 14.2 57.6 165 21 11 4.2 2.3 24.4 75.9 -9.5 254 1.3
7500 14.4 57.9 160 20 10 -1.9 -1.0 23.8 74.8 -10.1 243 1.2
7250 14.1 57.4 160 20 10 -1.1 -0.6 22.8 73.0 -11.1 244 1.2
7000 14.3 57.7 155 22 11 5.4 3.0 22.3 72.1 -11.7 231 1.2
6750 14.7 58.5 155 21 11 8.3 4.5 22.0 71.7 -12.0 211 1.1
6500 15.2 59.4 145 19 10 2.9 1.6 21.8 71.3 -12.3 190 1.0
6250 15.1 59.2 135 17 9 0.0 0.0 21.1 69.9 -13.1 183 0.9
6000 15.4 59.7 125 15 8 5.8 3.2 20.6 69.0 -13.6 168 0.9
5750 15.9 60.6 115 15 7 7.2 4.0 20.4 68.6 -13.9 146 0.7
5500 16.4 61.5 110 14 7 6.7 3.7 20.1 68.2 -14.1 123 0.6
5250 16.9 62.4 095 13 7 8.6 4.7 20.0 67.9 -14.4 100 0.5
5000 17.4 63.3 085 14 7 1.5 0.8 19.7 67.5 -14.7 78 0.4
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/22/2024 at 0900 MDT | 06/22/2024 at 1200 MDT
|
CAPE... +254.0 LI... -4.3 | CAPE... +916.0 LI... -5.9
CINH... -198.9 K Index... +26.5 | CINH... -27.9 K Index... +30.9
|
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 -61.8 -79.2 245 56 29 2.1 1.2 | -61.8 -79.2 250 57 30 2.1 1.1
45000 -57.0 -70.6 245 79 41 5.4 3.0 | -57.0 -70.6 250 78 40 5.3 2.9
40000 -48.2 -54.8 245 88 45 6.2 3.4 | -48.4 -55.1 245 87 45 6.3 3.5
38000 -44.5 -48.1 245 83 43 6.2 3.4 | -44.6 -48.3 245 82 42 6.3 3.5
36000 -40.8 -41.4 245 78 40 6.1 3.4 | -40.8 -41.4 245 77 40 6.3 3.5
34000 -37.3 -35.1 245 69 35 6.0 3.3 | -37.0 -34.6 245 70 36 6.4 3.5
32000 -33.7 -28.7 245 59 30 5.9 3.3 | -33.2 -27.8 245 62 32 6.3 3.5
30000 -30.1 -22.2 245 53 27 6.0 3.3 | -29.4 -20.9 245 56 29 6.4 3.5
29000 -28.3 -18.9 245 51 26 6.0 3.3 | -27.5 -17.5 250 54 28 6.4 3.5
28000 -26.5 -15.7 250 48 25 6.9 3.8 | -25.5 -13.9 250 51 26 6.2 3.4
27000 -24.2 -11.6 250 47 24 7.7 4.2 | -23.7 -10.7 250 49 25 6.1 3.4
26000 -21.9 -7.4 250 45 23 7.7 4.2 | -21.9 -7.4 250 47 24 6.1 3.4
25000 -19.6 -3.3 250 44 23 7.9 4.3 | -20.1 -4.2 250 44 23 6.1 3.4
24000 -17.2 1.0 255 40 21 6.2 3.4 | -17.8 -0.0 255 39 20 6.1 3.3
23000 -15.3 4.5 260 37 19 6.2 3.4 | -16.0 3.2 260 34 18 6.1 3.3
22000 -13.5 7.7 265 34 18 5.1 2.8 | -14.2 6.4 260 30 15 5.6 3.1
21000 -12.2 10.0 265 31 16 4.5 2.5 | -12.6 9.3 265 25 13 5.5 3.0
20000 -10.9 12.4 270 27 14 4.7 2.6 | -11.0 12.2 270 21 11 5.6 3.1
19500 -10.3 13.5 275 26 13 5.2 2.9 | -10.2 13.6 270 19 10 6.1 3.3
19000 -9.3 15.3 275 24 12 7.7 4.2 | -9.2 15.4 270 17 9 7.7 4.2
18500 -8.2 17.2 275 22 12 7.5 4.1 | -8.1 17.4 270 16 8 7.7 4.2
18000 -7.1 19.2 275 21 11 8.7 4.8 | -6.9 19.6 270 15 8 8.6 4.7
17500 -5.8 21.6 270 19 10 9.0 4.9 | -5.7 21.7 265 15 8 8.8 4.8
17000 -4.5 23.9 270 18 9 9.1 5.0 | -4.4 24.1 265 14 7 9.0 4.9
16500 -3.1 26.4 265 17 9 9.3 5.1 | -3.1 26.4 260 14 7 9.3 5.1
16000 -1.8 28.8 265 16 8 9.4 5.1 | -1.7 28.9 260 14 7 9.4 5.1
15500 -0.4 31.3 260 15 8 9.0 4.9 | -0.4 31.3 255 14 7 9.2 5.0
15000 0.9 33.6 255 15 7 9.0 5.0 | 1.0 33.8 255 14 7 9.2 5.1
14500 2.2 36.0 255 14 7 9.0 4.9 | 2.3 36.1 255 14 7 9.1 5.0
14000 3.5 38.3 250 13 7 8.9 4.9 | 3.6 38.5 250 14 7 9.0 5.0
13500 4.8 40.6 245 13 7 8.6 4.7 | 4.9 40.8 250 14 7 8.8 4.8
13000 6.0 42.8 235 13 7 8.2 4.5 | 6.1 43.0 245 14 7 8.6 4.7
12500 7.1 44.8 230 13 7 8.1 4.4 | 7.3 45.1 240 13 7 8.5 4.7
12000 8.2 46.8 225 13 6 7.8 4.3 | 8.5 47.3 240 13 7 8.4 4.6
11500 9.3 48.7 225 12 6 7.8 4.3 | 9.7 49.5 235 13 7 8.4 4.6
11000 10.4 50.7 220 12 6 7.3 4.0 | 10.8 51.4 235 12 6 8.0 4.4
10500 11.4 52.5 220 12 6 5.9 3.3 | 11.9 53.4 235 12 6 5.8 3.2
10250 11.7 53.1 220 12 6 5.2 2.9 | 12.2 54.0 235 11 6 6.0 3.3
10000 12.2 54.0 215 11 6 7.1 3.9 | 12.8 55.0 230 11 5 9.2 5.1
9750 12.6 54.7 215 11 6 7.1 3.9 | 13.5 56.3 230 10 5 8.5 4.6
9500 13.1 55.6 215 11 6 7.1 3.9 | 14.1 57.4 230 10 5 8.4 4.6
9250 13.6 56.5 215 11 6 7.2 4.0 | 14.6 58.3 230 9 4 7.5 4.1
9000 14.1 57.4 215 10 5 5.5 3.0 | 15.1 59.2 230 7 4 6.8 3.7
8750 14.8 58.6 205 10 5 5.0 2.7 | 15.6 60.1 230 7 4 6.7 3.7
8500 15.2 59.4 200 9 5 6.2 3.4 | 16.5 61.7 230 5 3 5.5 3.0
8250 15.6 60.1 200 9 5 5.2 2.9 | 17.0 62.6 235 4 2 7.6 4.2
8000 15.9 60.6 195 8 4 3.1 1.7 | 17.7 63.9 235 4 2 11.0 6.0
7750 16.1 61.0 185 8 4 3.3 1.8 | 18.5 65.3 230 4 2 9.2 5.0
7500 16.4 61.5 180 7 4 3.7 2.0 | 19.1 66.4 235 4 2 7.1 3.9
7250 16.6 61.9 170 7 4 3.8 2.1 | 19.6 67.3 240 3 2 8.8 4.8
7000 17.0 62.6 160 7 4 5.5 3.0 | 20.4 68.7 240 3 2 12.6 6.9
6750 17.4 63.3 155 6 3 6.4 3.5 | 21.4 70.5 240 3 2 11.7 6.4
6500 17.9 64.2 150 6 3 6.2 3.4 | 22.1 71.8 245 3 1 9.9 5.4
6250 18.3 64.9 140 6 3 5.7 3.1 | 22.9 73.2 250 2 1 8.9 4.9
6000 18.8 65.8 135 5 3 10.6 5.8 | 23.6 74.5 250 2 1 14.3 7.9
5750 19.9 67.8 130 4 2 20.0 11.0 | 25.2 77.4 250 2 1 29.5 16.2
5500 21.0 69.8 125 4 2 1.4 0.8 | 27.1 80.8 270 2 1 9.6 5.2
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
06/22/2024 at 1500 MDT | 06/22/2024 at 1800 MDT
|
CAPE... +811.6 LI... -4.2 | CAPE... +211.3 LI... -1.6
CINH... -5.2 K Index... +24.3 | CINH... -12.7 K Index... +25.2
|
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 -62.2 -80.0 250 58 30 2.0 1.1 | -62.5 -80.5 255 54 28 1.7 0.9
45000 -57.5 -71.5 250 76 39 5.3 2.9 | -57.9 -72.2 250 70 36 5.6 3.1
40000 -48.8 -55.8 250 81 42 6.6 3.6 | -48.9 -56.0 250 72 37 6.5 3.6
38000 -44.8 -48.6 250 75 39 6.6 3.6 | -45.0 -49.0 250 65 34 6.5 3.5
36000 -40.9 -41.6 250 69 36 6.6 3.6 | -41.1 -42.0 250 59 30 6.6 3.6
34000 -36.9 -34.4 250 63 32 6.6 3.6 | -37.1 -34.8 255 51 26 6.7 3.7
32000 -32.9 -27.2 255 56 29 6.6 3.6 | -33.1 -27.6 260 43 22 6.7 3.7
30000 -28.7 -19.7 255 51 26 7.0 3.9 | -28.9 -20.0 265 36 19 6.9 3.8
29000 -26.6 -15.9 255 49 25 7.0 3.9 | -26.9 -16.4 270 34 17 6.9 3.8
28000 -24.5 -12.1 260 46 24 6.3 3.4 | -24.8 -12.6 275 31 16 6.9 3.8
27000 -22.7 -8.9 260 44 22 5.9 3.2 | -22.7 -8.9 275 29 15 7.0 3.8
26000 -20.5 -4.9 260 40 21 5.9 3.2 | -20.6 -5.1 275 27 14 7.0 3.8
25000 -18.8 -1.8 260 37 19 6.1 3.4 | -18.1 -0.6 275 25 13 6.0 3.3
24000 -16.9 1.6 260 34 18 6.3 3.4 | -16.4 2.5 280 24 12 5.5 3.0
23000 -15.1 4.8 260 31 16 6.3 3.5 | -14.8 5.4 280 22 11 5.5 3.0
22000 -13.2 8.2 260 28 14 6.5 3.6 | -13.1 8.4 280 20 11 6.5 3.6
21000 -11.3 11.7 260 25 13 6.6 3.6 | -11.1 12.0 275 19 10 6.9 3.8
20000 -9.3 15.3 260 22 11 6.7 3.7 | -9.1 15.6 270 18 9 6.9 3.8
19500 -8.4 16.9 255 20 10 6.8 3.7 | -8.1 17.4 265 17 9 6.9 3.8
19000 -7.3 18.9 255 19 10 7.1 3.9 | -7.2 19.0 265 17 9 6.7 3.7
18500 -6.3 20.7 255 17 9 7.1 3.9 | -6.2 20.8 260 17 9 6.7 3.7
18000 -5.3 22.5 250 16 8 7.1 3.9 | -5.2 22.6 255 17 9 7.8 4.3
17500 -4.2 24.4 250 15 8 7.1 3.9 | -4.1 24.6 255 16 8 8.0 4.4
17000 -3.2 26.2 250 15 7 7.3 4.0 | -3.0 26.6 255 16 8 8.1 4.5
16500 -2.1 28.2 250 14 7 7.9 4.3 | -1.8 28.8 255 15 8 8.4 4.6
16000 -1.0 30.2 250 14 7 7.8 4.3 | -0.6 30.9 255 14 7 8.4 4.6
15500 0.2 32.4 250 14 7 8.8 4.8 | 0.7 33.3 255 13 7 9.0 4.9
15000 1.5 34.7 250 14 7 8.7 4.8 | 2.0 35.6 255 12 6 8.9 4.9
14500 2.8 37.0 250 14 7 8.9 4.9 | 3.3 37.9 255 11 6 8.9 4.9
14000 4.1 39.4 250 13 7 9.0 5.0 | 4.6 40.3 255 11 6 9.0 4.9
13500 5.4 41.7 250 13 7 9.2 5.1 | 6.0 42.8 255 10 5 9.1 5.0
13000 6.8 44.2 250 13 7 9.4 5.2 | 7.3 45.1 255 9 5 9.3 5.1
12500 8.1 46.6 250 13 6 9.4 5.2 | 8.7 47.7 255 9 5 9.3 5.1
12000 9.5 49.1 250 12 6 9.4 5.1 | 10.1 50.2 260 8 4 9.4 5.2
11500 10.9 51.6 250 12 6 9.3 5.1 | 11.5 52.7 260 8 4 9.4 5.2
11000 12.2 54.0 255 12 6 8.9 4.9 | 12.9 55.2 260 7 4 9.3 5.1
10500 13.5 56.3 255 11 6 8.0 4.4 | 14.3 57.7 260 7 4 7.5 4.1
10250 14.0 57.2 255 11 6 8.3 4.5 | 14.8 58.6 265 7 4 7.9 4.3
10000 14.7 58.5 255 11 5 9.7 5.3 | 15.6 60.1 265 7 3 10.6 5.8
9750 15.3 59.5 255 10 5 9.2 5.1 | 16.3 61.3 265 6 3 9.9 5.4
9500 16.0 60.8 255 10 5 9.9 5.4 | 17.0 62.6 265 6 3 9.9 5.4
9250 16.7 62.1 255 9 5 10.2 5.6 | 17.7 63.9 265 6 3 9.3 5.1
9000 17.4 63.3 260 9 4 9.2 5.0 | 18.4 65.1 270 6 3 9.1 5.0
8750 18.6 65.5 255 8 4 8.7 4.8 | 19.7 67.5 265 5 3 9.1 5.0
8500 19.2 66.6 260 8 4 7.9 4.3 | 20.3 68.5 270 5 3 8.2 4.5
8250 19.8 67.6 265 7 4 9.5 5.2 | 21.0 69.8 270 5 3 9.5 5.2
8000 20.6 69.1 260 7 4 11.8 6.5 | 21.7 71.1 270 5 2 11.4 6.3
7750 21.4 70.5 260 7 4 9.9 5.4 | 22.5 72.5 265 4 2 9.9 5.4
7500 22.0 71.6 260 7 3 7.9 4.3 | 23.2 73.8 270 4 2 8.3 4.5
7250 22.7 72.9 265 6 3 9.1 5.0 | 23.8 74.8 270 4 2 9.1 5.0
7000 23.4 74.1 265 6 3 12.0 6.6 | 24.6 76.3 270 4 2 11.2 6.1
6750 24.3 75.7 260 6 3 11.4 6.3 | 25.4 77.7 265 3 2 11.1 6.1
6500 25.1 77.2 265 6 3 10.2 5.6 | 26.2 79.2 270 3 2 10.4 5.7
6250 25.9 78.6 270 5 3 9.4 5.2 | 27.0 80.6 275 3 2 9.8 5.4
6000 26.6 79.9 270 5 3 12.8 7.0 | 27.7 81.9 275 3 2 10.4 5.7
5750 27.9 82.2 265 5 3 24.9 13.6 | 28.7 83.7 270 3 1 16.8 9.2
5500 29.8 85.6 275 5 2 20.1 11.0 | 30.2 86.4 290 3 1 23.7 13.0
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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