Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
802
UXUS97 KGJT 201307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Thursday, June 20, 2024
This forecast is for Thursday, June 20, 2024:
If the trigger temperature of 81.9 F/27.7 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1645 ft/min (8.4 m/s)
Maximum height of thermals.................. 20170 ft MSL (15308 ft AGL)
Forecast maximum temperature................... 93.0 F/34.3 C
Time of trigger temperature.................... 0945 MDT
Time of overdevelopment........................ 1600 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 13089 ft MSL (8227 ft AGL)
Thermal soaring outlook for Friday 06/21....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:48:19 / 20:43:30 MDT
Total possible sunshine........... 14 hr 55 min 11 sec (895 min 11 sec)
Altitude of sun at 13:15:54 MDT... 73.96 degrees
Upper air data from rawinsonde observation taken on 06/20/2024 at 0600 MDT
Freezing level.................. 15168 ft MSL (10306 ft AGL)
Convective condensation level... 15382 ft MSL (10520 ft AGL)
Lifted condensation level....... 16660 ft MSL (11798 ft AGL)
Lifted index.................... -4.7
K index......................... +25.8
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 -62.4 -80.3 225 66 34 -1.9 -1.0 90.2 194.4 32.7 M M
45000 -59.1 -74.4 225 68 35 4.7 2.6 71.3 160.3 23.2 M M
40000 -51.5 -60.7 230 71 36 6.3 3.5 60.4 140.7 17.6 M M
38000 -48.3 -54.9 235 60 31 4.2 2.3 56.3 133.4 15.3 M M
36000 -43.9 -47.0 235 55 28 6.6 3.6 53.2 127.8 13.6 M M
34000 -40.1 -40.2 235 52 27 7.1 3.9 50.2 122.4 11.8 M M
32000 -35.8 -32.4 240 49 25 6.4 3.5 48.1 118.6 10.5 M M
30000 -31.2 -24.2 235 48 25 8.9 4.9 46.5 115.7 9.5 M M
29000 -28.5 -19.3 240 49 25 8.9 4.9 46.1 115.0 9.4 M M
28000 -25.9 -14.6 240 47 24 9.0 5.0 45.7 114.3 9.2 M M
27000 -23.9 -11.0 235 51 26 0.8 0.5 44.5 112.0 8.3 M M
26000 -23.8 -10.8 235 49 25 10.3 5.7 40.9 105.6 5.5 M M
25000 -21.5 -6.7 230 51 26 4.0 2.2 40.2 104.3 5.0 M M
24000 -19.9 -3.8 230 49 25 7.0 3.9 38.6 101.5 3.7 M M
23000 -17.9 -0.2 230 52 27 7.2 4.0 37.5 99.5 2.8 M M
22000 -15.8 3.6 225 49 25 6.9 3.8 36.5 97.7 2.0 M M
21000 -13.6 7.5 220 47 24 7.2 3.9 35.6 96.0 1.3 M M
20000 -11.7 10.9 215 50 26 6.9 3.8 33.8 92.9 -0.3 1421 7.2
19500 -10.7 12.7 215 51 26 6.9 3.8 33.3 92.0 -0.8 1378 7.0
19000 -9.8 14.4 215 44 23 6.4 3.5 32.8 91.0 -1.4 1335 6.8
18500 -8.8 16.2 215 43 22 6.6 3.6 32.2 90.0 -1.9 1292 6.6
18000 -7.7 18.1 210 36 19 8.9 4.9 31.9 89.4 -2.2 1242 6.3
17500 -6.4 20.5 210 33 17 9.1 5.0 31.7 89.1 -2.4 1189 6.0
17000 -5.0 23.0 215 29 15 9.3 5.1 31.7 89.1 -2.4 1133 5.8
16500 -3.6 25.5 215 26 14 9.4 5.1 31.7 89.1 -2.5 1076 5.5
16000 -2.2 28.0 215 29 15 9.4 5.1 31.7 89.0 -2.5 1020 5.2
15500 -0.8 30.6 215 28 14 9.4 5.1 31.6 88.9 -2.6 963 4.9
15000 0.6 33.1 210 30 15 9.4 5.1 31.6 88.9 -2.7 907 4.6
14500 2.0 35.6 210 26 13 9.4 5.1 31.5 88.8 -2.7 850 4.3
14000 3.4 38.1 210 25 13 9.4 5.1 31.5 88.7 -2.8 794 4.0
13500 4.8 40.6 210 23 12 9.4 5.1 31.4 88.5 -2.9 737 3.7
13000 6.1 43.0 215 23 12 9.4 5.1 31.3 88.4 -3.0 681 3.5
12500 7.5 45.5 210 23 12 9.4 5.1 31.2 88.2 -3.1 624 3.2
12000 8.9 48.0 205 25 13 9.4 5.1 31.2 88.1 -3.2 568 2.9
11500 10.3 50.5 205 27 14 9.4 5.1 31.1 87.9 -3.4 511 2.6
11000 11.7 53.1 210 29 15 9.4 5.1 31.0 87.7 -3.5 455 2.3
10500 13.1 55.6 210 29 15 11.0 6.0 30.9 87.6 -3.6 397 2.0
10250 13.8 56.8 210 31 16 5.4 2.9 30.9 87.6 -3.7 370 1.9
10000 13.8 56.8 195 31 16 -0.2 -0.1 30.2 86.4 -4.4 362 1.8
9750 13.8 56.8 195 31 16 2.7 1.5 29.5 85.2 -5.1 355 1.8
9500 14.0 57.2 190 30 15 7.2 3.9 29.1 84.4 -5.6 340 1.7
9250 14.6 58.3 190 29 15 9.7 5.3 29.1 84.3 -5.8 315 1.6
9000 15.3 59.5 185 28 14 9.3 5.1 29.0 84.3 -5.9 287 1.5
8750 16.0 60.8 185 28 14 9.5 5.2 29.0 84.2 -5.9 259 1.3
8500 16.7 62.1 180 27 14 9.0 5.0 29.0 84.2 -6.0 232 1.2
8250 17.3 63.1 180 27 14 7.8 4.3 28.9 84.0 -6.1 206 1.0
8000 17.8 64.0 185 28 15 7.4 4.1 28.7 83.7 -6.4 183 0.9
7750 18.3 64.9 180 28 14 7.5 4.1 28.5 83.4 -6.6 160 0.8
7500 18.9 66.0 175 26 14 7.6 4.2 28.4 83.1 -6.8 137 0.7
7250 19.5 67.1 170 25 13 7.8 4.3 28.2 82.8 -6.9 111 0.6
7000 20.1 68.2 170 23 12 7.7 4.2 28.1 82.5 -7.1 85 0.4
6750 20.7 69.3 165 24 12 7.8 4.3 27.9 82.2 -7.2 59 0.3
6500 21.3 70.3 155 24 13 7.8 4.3 27.8 82.0 -7.3 33 0.2
6250 21.9 71.4 150 25 13 7.7 4.2 27.6 81.7 -7.4 7 0.0
6000 22.6 72.7 145 24 12 8.2 4.5 27.5 81.4 -7.6 M M
5750 23.2 73.8 145 22 12 6.3 3.4 27.3 81.2 -7.7 M M
5500 23.5 74.3 135 21 11 -1.3 -0.7 26.8 80.2 -8.2 M M
5250 23.3 73.9 125 20 10 -5.7 -3.1 25.7 78.3 -9.1 M M
5000 22.8 73.0 120 21 11 -8.9 -4.9 24.5 76.1 -10.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
06/20/2024 at 0900 MDT | 06/20/2024 at 1200 MDT
|
CAPE... +538.4 LI... -3.8 | CAPE... +984.3 LI... -4.2
CINH... -53.5 K Index... +24.0 | CINH... -2.6 K Index... +31.5
|
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 -60.8 -77.4 235 60 31 0.5 0.3 | -61.1 -78.0 235 64 33 0.9 0.5
45000 -58.5 -73.3 230 74 38 4.2 2.3 | -57.9 -72.2 235 81 42 4.3 2.4
40000 -51.4 -60.5 225 66 34 7.0 3.8 | -51.0 -59.8 230 71 37 6.6 3.6
38000 -47.2 -53.0 225 61 32 7.0 3.9 | -47.0 -52.6 230 66 34 6.7 3.7
36000 -42.9 -45.2 225 56 29 7.1 3.9 | -43.0 -45.4 230 60 31 6.7 3.7
34000 -39.1 -38.4 225 52 27 6.2 3.4 | -39.2 -38.6 230 56 29 6.3 3.4
32000 -35.4 -31.7 230 47 24 6.2 3.4 | -35.4 -31.7 225 51 26 6.2 3.4
30000 -31.4 -24.5 230 45 23 6.8 3.7 | -31.5 -24.7 225 46 24 6.6 3.6
29000 -29.4 -20.9 235 44 23 6.8 3.7 | -29.5 -21.1 225 44 22 6.6 3.6
28000 -27.4 -17.3 235 44 23 6.7 3.7 | -27.5 -17.5 225 41 21 6.8 3.7
27000 -25.4 -13.7 235 43 22 6.4 3.5 | -24.8 -12.6 225 39 20 7.3 4.0
26000 -23.5 -10.3 235 42 22 6.4 3.5 | -22.7 -8.9 225 37 19 7.3 4.0
25000 -21.1 -6.0 230 41 21 6.4 3.5 | -20.5 -4.9 225 35 18 7.2 4.0
24000 -19.3 -2.7 230 41 21 6.3 3.5 | -18.4 -1.1 220 34 18 7.1 3.9
23000 -17.4 0.7 230 40 21 6.3 3.5 | -16.2 2.8 220 34 18 7.1 3.9
22000 -15.5 4.1 225 40 21 6.7 3.7 | -14.1 6.6 220 34 18 6.7 3.7
21000 -13.5 7.7 225 40 21 7.1 3.9 | -12.3 9.9 215 34 18 6.2 3.4
20000 -11.4 11.5 225 41 21 7.2 3.9 | -10.5 13.1 215 34 17 6.3 3.4
19500 -10.4 13.3 220 41 21 7.2 3.9 | -9.6 14.7 215 34 17 6.3 3.5
19000 -9.3 15.3 220 41 21 7.9 4.4 | -8.7 16.3 215 34 17 6.6 3.6
18500 -8.1 17.4 220 41 21 7.9 4.3 | -7.7 18.1 215 33 17 6.7 3.7
18000 -7.0 19.4 220 41 21 8.1 4.5 | -6.8 19.8 215 33 17 7.6 4.2
17500 -5.8 21.6 220 40 21 8.3 4.5 | -5.6 21.9 215 33 17 8.2 4.5
17000 -4.6 23.7 220 40 21 8.3 4.6 | -4.5 23.9 215 32 17 8.3 4.5
16500 -3.3 26.1 215 39 20 8.8 4.8 | -3.2 26.2 215 32 16 8.7 4.8
16000 -2.0 28.4 215 38 20 8.8 4.8 | -1.9 28.6 215 31 16 8.7 4.8
15500 -0.7 30.7 215 37 19 8.9 4.9 | -0.7 30.7 215 30 16 8.8 4.8
15000 0.7 33.3 215 36 18 8.9 4.9 | 0.6 33.1 210 30 15 8.8 4.8
14500 2.0 35.6 215 35 18 8.9 4.9 | 1.9 35.4 210 29 15 8.8 4.9
14000 3.3 37.9 210 33 17 8.8 4.8 | 3.2 37.8 210 28 14 8.9 4.9
13500 4.6 40.3 210 32 16 8.8 4.8 | 4.5 40.1 210 27 14 8.9 4.9
13000 5.9 42.6 210 31 16 8.8 4.8 | 5.8 42.4 205 27 14 8.9 4.9
12500 7.2 45.0 210 30 15 8.8 4.8 | 7.1 44.8 205 26 14 8.9 4.9
12000 8.5 47.3 210 29 15 8.3 4.6 | 8.4 47.1 205 26 14 9.2 5.1
11500 9.7 49.5 205 28 14 8.4 4.6 | 9.7 49.5 205 26 14 9.2 5.1
11000 10.9 51.6 205 28 14 8.0 4.4 | 10.9 51.6 205 26 13 8.3 4.5
10500 12.0 53.6 205 28 14 8.5 4.7 | 12.1 53.8 205 25 13 10.1 5.5
10250 12.7 54.9 205 29 15 7.8 4.3 | 12.9 55.2 205 25 13 10.9 6.0
10000 13.1 55.6 200 29 15 6.8 3.7 | 13.6 56.5 205 25 13 9.1 5.0
9750 13.6 56.5 200 29 15 7.1 3.9 | 14.3 57.7 205 25 13 9.5 5.2
9500 14.1 57.4 195 29 15 7.2 3.9 | 15.0 59.0 205 25 13 9.6 5.3
9250 14.6 58.3 195 29 15 8.9 4.9 | 15.7 60.3 205 24 12 10.3 5.6
9000 15.5 59.9 195 28 15 4.9 2.7 | 17.2 63.0 205 24 12 9.6 5.3
8750 15.8 60.4 190 27 14 5.7 3.1 | 17.9 64.2 210 24 12 9.7 5.3
8500 16.2 61.2 190 26 13 6.0 3.3 | 18.6 65.5 210 23 12 8.9 4.9
8250 16.7 62.1 190 25 13 6.2 3.4 | 19.3 66.7 210 23 12 9.7 5.3
8000 17.1 62.8 185 23 12 6.0 3.3 | 20.1 68.2 210 23 12 11.0 6.1
7750 17.5 63.5 185 20 10 6.2 3.4 | 20.9 69.6 210 22 11 10.1 5.5
7500 18.0 64.4 180 19 10 6.3 3.4 | 21.6 70.9 210 22 11 8.6 4.7
7250 18.5 65.3 180 19 10 6.8 3.7 | 22.2 72.0 210 22 11 9.1 5.0
7000 19.0 66.2 180 17 9 9.0 4.9 | 23.0 73.4 210 21 11 11.9 6.5
6750 19.8 67.6 175 14 7 10.3 5.7 | 23.9 75.0 210 21 11 11.9 6.5
6500 20.5 68.9 175 14 7 10.4 5.7 | 24.7 76.5 210 20 10 11.0 6.0
6250 21.3 70.3 175 14 7 9.9 5.4 | 25.5 77.9 210 20 10 10.3 5.6
6000 22.0 71.6 175 13 7 10.7 5.9 | 26.3 79.3 210 19 10 12.8 7.0
5750 23.0 73.4 170 11 6 17.2 9.4 | 27.7 81.9 210 17 9 26.1 14.3
5500 24.7 76.5 170 10 5 28.6 15.7 | 30.2 86.4 210 16 8 42.0 23.0
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
06/20/2024 at 1500 MDT | 06/20/2024 at 1800 MDT
|
CAPE... +634.5 LI... -3.3 | CAPE... +576.2 LI... -2.1
CINH... -2.3 K Index... +31.5 | CINH... -81.8 K Index... +32.0
|
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 -61.3 -78.3 235 65 34 0.3 0.1 | -62.4 -80.3 235 66 34 1.5 0.8
45000 -58.2 -72.8 235 84 43 5.7 3.1 | -58.1 -72.6 235 80 41 5.6 3.1
40000 -49.8 -57.6 230 76 39 5.3 2.9 | -49.8 -57.6 225 80 41 5.3 2.9
38000 -46.6 -51.9 225 70 36 5.3 2.9 | -46.2 -51.2 220 70 36 5.3 2.9
36000 -43.1 -45.6 220 64 33 5.7 3.1 | -43.0 -45.4 215 60 31 5.8 3.2
34000 -38.7 -37.7 225 58 30 7.4 4.0 | -38.5 -37.3 215 55 28 7.8 4.3
32000 -34.3 -29.7 225 52 27 7.4 4.1 | -33.8 -28.8 220 50 26 7.8 4.3
30000 -30.4 -22.7 225 46 24 6.5 3.6 | -29.7 -21.5 220 46 24 6.6 3.6
29000 -28.4 -19.1 225 43 22 6.5 3.6 | -27.8 -18.0 220 45 23 6.6 3.6
28000 -26.5 -15.7 225 40 21 6.9 3.8 | -25.8 -14.4 220 43 22 6.5 3.6
27000 -24.4 -11.9 220 39 20 7.1 3.9 | -23.9 -11.0 220 42 21 6.5 3.5
26000 -22.2 -8.0 220 37 19 7.1 3.9 | -22.0 -7.6 220 40 21 6.5 3.6
25000 -20.1 -4.2 220 36 18 7.2 3.9 | -20.1 -4.2 215 39 20 6.4 3.5
24000 -18.3 -0.9 215 35 18 5.8 3.2 | -18.0 -0.4 215 37 19 7.0 3.9
23000 -16.6 2.1 215 34 18 5.9 3.2 | -15.5 4.1 215 34 18 7.1 3.9
22000 -14.5 5.9 215 33 17 7.1 3.9 | -13.4 7.9 215 32 16 7.5 4.1
21000 -12.3 9.9 210 33 17 7.7 4.2 | -11.2 11.8 215 29 15 7.7 4.2
20000 -10.0 14.0 210 32 16 7.7 4.2 | -8.9 16.0 215 27 14 7.8 4.3
19500 -8.9 16.0 210 32 16 7.9 4.3 | -7.8 18.0 210 26 14 7.7 4.2
19000 -7.8 18.0 210 32 16 8.2 4.5 | -6.7 19.9 210 25 13 7.4 4.0
18500 -6.6 20.1 210 31 16 8.2 4.5 | -5.7 21.7 210 24 13 7.4 4.1
18000 -5.4 22.3 210 31 16 8.3 4.6 | -4.6 23.7 210 23 12 7.4 4.1
17500 -4.2 24.4 210 30 16 8.4 4.6 | -3.5 25.7 210 22 12 7.4 4.1
17000 -3.0 26.6 210 30 15 8.5 4.7 | -2.5 27.5 210 22 11 7.5 4.1
16500 -1.7 28.9 210 29 15 8.9 4.9 | -1.3 29.7 210 21 11 8.1 4.5
16000 -0.5 31.1 210 29 15 8.9 4.9 | -0.1 31.8 210 20 10 8.1 4.4
15500 0.8 33.4 210 28 15 8.9 4.9 | 1.1 34.0 205 19 10 8.5 4.7
15000 2.1 35.8 210 28 14 9.0 4.9 | 2.3 36.1 205 19 10 8.6 4.7
14500 3.4 38.1 210 27 14 9.3 5.1 | 3.6 38.5 205 19 10 8.7 4.8
14000 4.8 40.6 210 26 14 9.4 5.2 | 4.8 40.6 200 18 9 8.7 4.8
13500 6.2 43.2 210 26 13 9.5 5.2 | 6.1 43.0 200 18 9 8.6 4.7
13000 7.6 45.7 210 25 13 9.6 5.3 | 7.3 45.1 200 18 9 8.2 4.5
12500 9.0 48.2 210 25 13 9.6 5.3 | 8.5 47.3 195 18 9 8.2 4.5
12000 10.4 50.7 210 24 13 9.6 5.3 | 9.7 49.5 195 17 9 8.0 4.4
11500 11.8 53.2 210 24 12 9.6 5.3 | 10.8 51.4 195 17 9 8.1 4.4
11000 13.2 55.8 210 24 12 9.0 4.9 | 11.9 53.4 195 16 8 6.6 3.6
10500 14.5 58.1 210 23 12 11.0 6.0 | 12.9 55.2 195 15 8 8.7 4.8
10250 15.4 59.7 210 23 12 11.4 6.3 | 13.6 56.5 190 15 8 9.1 5.0
10000 16.1 61.0 215 23 12 9.1 5.0 | 14.1 57.4 190 15 8 6.6 3.6
9750 16.8 62.2 215 22 11 9.7 5.3 | 14.6 58.3 190 15 8 7.3 4.0
9500 17.5 63.5 215 22 11 9.7 5.3 | 15.1 59.2 190 15 7 7.2 4.0
9250 18.3 64.9 215 22 11 10.0 5.5 | 15.6 60.1 190 14 7 6.5 3.6
9000 19.0 66.2 215 21 11 9.6 5.3 | 16.1 61.0 195 14 7 6.7 3.7
8750 19.7 67.5 215 21 11 9.3 5.1 | 17.1 62.8 200 13 7 7.3 4.0
8500 20.4 68.7 215 21 11 9.4 5.2 | 17.7 63.9 200 13 7 7.7 4.2
8250 21.7 71.1 215 20 10 9.7 5.3 | 18.2 64.8 200 13 7 7.9 4.3
8000 22.5 72.5 220 20 10 11.1 6.1 | 18.8 65.8 205 12 6 7.9 4.3
7750 23.3 73.9 220 19 10 10.2 5.6 | 19.4 66.9 205 12 6 7.8 4.3
7500 24.0 75.2 220 19 10 8.3 4.6 | 19.9 67.8 205 11 6 6.9 3.8
7250 24.6 76.3 220 19 10 8.7 4.8 | 20.4 68.7 205 11 6 7.0 3.8
7000 25.4 77.7 220 18 9 11.3 6.2 | 20.9 69.6 205 11 6 8.6 4.7
6750 26.2 79.2 220 17 9 11.5 6.3 | 21.6 70.9 205 9 5 9.1 5.0
6500 27.0 80.6 220 17 9 10.7 5.9 | 22.2 72.0 205 9 5 8.7 4.8
6250 27.8 82.0 220 17 9 10.7 5.9 | 22.8 73.0 200 9 5 8.7 4.8
6000 28.6 83.5 220 16 8 9.4 5.1 | 23.4 74.1 200 9 5 7.7 4.2
5750 29.4 84.9 225 14 7 16.0 8.8 | 24.0 75.2 195 7 3 11.5 6.3
5500 31.9 89.4 225 13 7 60.8 33.3 | 25.6 78.1 195 7 3 40.1 22.0
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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