Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
095
UXUS97 KGJT 241307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Friday, May 24, 2024
This forecast is for Friday, May 24, 2024:
If the trigger temperature of 58.6 F/14.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1072 ft/min (5.4 m/s)
Maximum height of thermals.................. 17596 ft MSL (12757 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 1000 MDT
Time of overdevelopment........................ 1700 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 12959 ft MSL (8120 ft AGL)
Thermal soaring outlook for Saturday 05/25..... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:53:36 / 20:28:32 MDT
Total possible sunshine........... 14 hr 34 min 56 sec (874 min 56 sec)
Altitude of sun at 13:11:04 MDT... 71.69 degrees
Upper air data from rawinsonde observation taken on 05/24/2024 at 0600 MDT
Freezing level.................. 10055 ft MSL (5216 ft AGL)
Convective condensation level... 17719 ft MSL (12880 ft AGL)
Lifted condensation level....... 17955 ft MSL (13116 ft AGL)
Lifted index.................... +1.6
K index......................... -12.2
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 -56.4 -69.5 265 50 26 3.8 2.1 106.6 223.9 47.5 M M
45000 -51.6 -60.9 270 64 33 1.4 0.8 88.7 191.7 40.0 M M
40000 -55.2 -67.4 260 76 39 -8.8 -4.8 60.1 140.1 24.0 M M
38000 -55.7 -68.3 265 77 40 2.6 1.4 50.4 122.8 18.2 M M
36000 -54.3 -65.7 265 70 36 5.0 2.8 43.9 110.9 14.2 M M
34000 -51.2 -60.2 265 72 37 7.0 3.8 39.9 103.9 11.8 M M
32000 -46.3 -51.3 270 68 35 7.7 4.2 37.7 99.9 10.5 M M
30000 -41.2 -42.2 265 68 35 8.1 4.4 36.8 98.2 10.0 M M
29000 -38.8 -37.8 265 69 35 8.0 4.4 36.1 97.0 9.7 M M
28000 -36.5 -33.7 265 63 32 6.7 3.7 35.2 95.3 9.1 M M
27000 -34.5 -30.1 260 57 29 6.6 3.6 34.0 93.2 8.3 M M
26000 -32.5 -26.5 260 55 28 6.6 3.6 32.8 91.0 7.4 M M
25000 -30.5 -22.9 265 50 26 6.7 3.6 31.7 89.0 6.6 M M
24000 -28.6 -19.5 265 51 26 6.6 3.6 30.5 86.8 5.7 M M
23000 -26.6 -15.9 270 47 24 6.6 3.6 29.2 84.6 4.7 M M
22000 -24.6 -12.3 270 44 23 6.7 3.7 28.2 82.7 3.9 M M
21000 -22.6 -8.7 265 47 24 6.8 3.7 27.1 80.8 3.1 M M
20000 -20.5 -4.9 275 40 20 6.8 3.7 26.0 78.8 2.2 M M
19500 -19.5 -3.1 275 35 18 6.8 3.7 25.5 77.8 1.8 M M
19000 -18.5 -1.3 280 30 15 6.6 3.6 24.9 76.9 1.4 M M
18500 -17.8 -0.0 270 26 13 5.2 2.9 23.9 75.1 0.5 M M
18000 -16.6 2.1 275 25 13 7.9 4.3 23.7 74.6 0.3 M M
17500 -14.8 5.4 275 25 13 8.2 4.5 23.3 73.9 -0.1 1049 5.3
17000 -13.6 7.5 270 24 13 8.4 4.6 23.0 73.5 -0.3 997 5.1
16500 -12.3 9.9 270 27 14 8.4 4.6 22.8 73.1 -0.5 945 4.8
16000 -11.0 12.2 270 29 15 8.4 4.6 22.6 72.7 -0.7 892 4.5
15500 -9.8 14.4 270 27 14 8.4 4.6 22.3 72.2 -0.9 840 4.3
15000 -8.5 16.7 275 26 13 8.4 4.6 22.1 71.8 -1.2 787 4.0
14500 -7.3 18.9 280 24 12 8.0 4.4 21.8 71.3 -1.4 736 3.7
14000 -6.1 21.0 280 25 13 8.1 4.4 21.6 70.8 -1.7 686 3.5
13500 -5.0 23.0 280 25 13 5.2 2.8 21.2 70.2 -2.1 638 3.2
13000 -4.5 23.9 275 23 12 3.8 2.1 20.2 68.3 -3.0 607 3.1
12500 -4.0 24.8 265 20 10 3.8 2.1 19.2 66.6 -4.0 577 2.9
12000 -3.4 25.9 255 18 9 4.3 2.3 18.3 64.9 -4.9 545 2.8
11500 -2.8 27.0 260 18 9 4.5 2.5 17.4 63.4 -5.7 511 2.6
11000 -2.1 28.2 255 15 8 4.8 2.6 16.6 61.9 -6.6 477 2.4
10500 -1.1 30.0 245 13 7 8.6 4.7 16.2 61.1 -7.0 431 2.2
10250 -0.5 31.1 235 12 6 8.2 4.5 16.0 60.9 -7.2 405 2.1
10000 0.1 32.2 230 11 6 7.8 4.3 15.9 60.6 -7.3 380 1.9
9750 0.7 33.3 230 10 5 7.3 4.0 15.7 60.3 -7.5 356 1.8
9500 1.3 34.3 225 8 4 7.5 4.1 15.5 60.0 -7.7 331 1.7
9250 1.8 35.2 225 7 4 7.4 4.1 15.4 59.7 -7.9 307 1.6
9000 2.4 36.3 220 6 3 7.5 4.1 15.2 59.3 -8.0 283 1.4
8750 2.9 37.2 220 5 3 7.3 4.0 15.0 59.0 -8.2 259 1.3
8500 3.5 38.3 230 5 2 8.2 4.5 14.8 58.7 -8.4 235 1.2
8250 4.0 39.2 245 4 2 5.1 2.8 14.7 58.4 -8.7 212 1.1
8000 4.1 39.4 085 2 1 -2.4 -1.3 14.0 57.2 -9.4 203 1.0
7750 3.8 38.8 075 3 2 0.9 0.5 13.1 55.5 -10.3 202 1.0
7500 4.2 39.6 065 4 2 7.3 4.0 12.7 54.9 -10.7 183 0.9
7250 4.8 40.6 060 5 3 7.2 4.0 12.5 54.5 -10.9 160 0.8
7000 5.3 41.5 065 6 3 7.2 4.0 12.3 54.2 -11.2 136 0.7
6750 5.8 42.4 065 6 3 7.3 4.0 12.1 53.8 -11.4 113 0.6
6500 6.4 43.5 060 5 3 7.2 3.9 11.9 53.5 -11.6 89 0.5
6250 6.9 44.4 055 5 2 7.6 4.2 11.8 53.2 -11.8 66 0.3
6000 7.4 45.3 055 4 2 6.0 3.3 11.6 52.8 -12.0 42 0.2
5750 7.8 46.0 090 4 2 3.6 2.0 11.2 52.1 -12.5 25 0.1
5500 8.0 46.4 130 3 1 3.2 1.7 10.7 51.2 -13.0 11 0.1
5250 8.2 46.8 170 4 2 4.3 2.3 10.2 50.4 -13.5 M M
5000 8.5 47.3 175 5 3 0.4 0.2 9.7 49.5 -14.1 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/24/2024 at 0900 MDT | 05/24/2024 at 1200 MDT
|
CAPE... 0.0 LI... +4.8 | CAPE... 0.0 LI... +3.4
CINH... -0.1 K Index... +0.7 | CINH... 0.0 K Index... +10.7
|
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 -55.1 -67.2 260 49 25 1.8 1.0 | -55.5 -67.9 260 55 28 1.2 0.6
45000 -52.7 -62.9 260 59 30 -2.0 -1.1 | -54.0 -65.2 260 71 37 -1.3 -0.7
40000 -55.4 -67.7 265 77 39 -1.8 -1.0 | -55.7 -68.3 265 81 42 -1.2 -0.7
38000 -54.7 -66.5 265 81 41 3.0 1.6 | -54.8 -66.6 265 83 43 3.2 1.7
36000 -53.0 -63.4 265 82 42 3.0 1.6 | -52.9 -63.2 265 86 44 3.2 1.7
34000 -50.1 -58.2 270 82 42 7.4 4.1 | -49.7 -57.5 265 86 44 8.0 4.4
32000 -45.6 -50.1 270 78 40 7.4 4.1 | -44.9 -48.8 265 82 42 8.0 4.4
30000 -41.0 -41.8 265 74 38 8.1 4.5 | -40.2 -40.4 265 77 40 8.0 4.4
29000 -38.6 -37.5 265 71 37 8.1 4.5 | -37.8 -36.0 265 74 38 8.0 4.4
28000 -36.2 -33.2 265 69 36 8.1 4.5 | -35.4 -31.7 265 71 36 8.0 4.4
27000 -33.8 -28.8 265 67 34 7.2 3.9 | -33.1 -27.6 265 68 35 7.1 3.9
26000 -31.8 -25.2 265 62 32 6.9 3.8 | -31.0 -23.8 265 64 33 7.0 3.8
25000 -29.7 -21.5 265 58 30 6.9 3.8 | -28.9 -20.0 265 61 31 7.0 3.8
24000 -27.7 -17.9 265 54 28 6.6 3.6 | -26.9 -16.4 265 58 30 6.3 3.4
23000 -25.9 -14.6 265 50 26 5.9 3.2 | -25.3 -13.5 265 54 28 5.3 2.9
22000 -24.1 -11.4 265 47 24 5.9 3.3 | -23.7 -10.7 265 50 25 5.3 2.9
21000 -21.9 -7.4 270 43 22 6.4 3.5 | -21.6 -6.9 265 45 23 6.6 3.6
20000 -20.0 -4.0 270 41 21 6.4 3.5 | -19.7 -3.5 265 41 21 6.6 3.6
19500 -19.1 -2.4 270 40 21 6.4 3.5 | -18.7 -1.7 265 39 20 6.6 3.6
19000 -18.1 -0.6 275 39 20 6.4 3.5 | -17.7 0.1 265 38 19 6.5 3.5
18500 -17.2 1.0 275 38 20 6.5 3.6 | -16.7 1.9 265 36 19 7.7 4.2
18000 -16.2 2.8 275 37 19 6.6 3.6 | -15.6 3.9 265 36 18 7.6 4.2
17500 -15.2 4.6 275 36 18 6.9 3.8 | -14.5 5.9 265 35 18 7.6 4.2
17000 -14.1 6.6 275 35 18 7.3 4.0 | -13.4 7.9 265 34 18 7.5 4.1
16500 -13.1 8.4 275 33 17 7.3 4.0 | -12.3 9.9 265 33 17 7.5 4.1
16000 -11.9 10.6 275 33 17 8.1 4.5 | -11.2 11.8 265 33 17 7.3 4.0
15500 -10.7 12.7 275 32 16 8.0 4.4 | -10.1 13.8 265 32 16 7.3 4.0
15000 -9.5 14.9 275 31 16 8.3 4.5 | -9.0 15.8 265 30 16 7.6 4.2
14500 -8.2 17.2 275 30 15 8.3 4.6 | -7.9 17.8 265 29 15 7.6 4.2
14000 -7.0 19.4 275 29 15 8.1 4.4 | -6.7 19.9 265 27 14 7.9 4.3
13500 -5.8 21.6 275 28 14 7.9 4.4 | -5.5 22.1 265 26 13 8.0 4.4
13000 -4.5 23.9 275 26 14 7.6 4.2 | -4.3 24.3 265 24 12 7.8 4.3
12500 -3.5 25.7 275 24 12 7.2 3.9 | -3.1 26.4 265 22 11 7.7 4.2
12000 -2.4 27.7 275 22 11 6.7 3.7 | -1.9 28.6 265 20 10 7.6 4.2
11500 -1.5 29.3 275 20 10 6.1 3.3 | -0.8 30.6 265 18 9 7.4 4.1
11000 -0.6 30.9 275 17 9 5.5 3.0 | 0.3 32.5 265 16 8 6.7 3.7
10500 0.1 32.2 270 14 7 4.6 2.5 | 1.2 34.2 265 14 7 5.2 2.8
10250 0.4 32.7 270 13 7 4.3 2.4 | 1.7 35.1 265 14 7 8.6 4.7
10000 0.7 33.3 265 11 6 5.1 2.8 | 2.4 36.3 260 11 6 9.4 5.2
9750 1.1 34.0 260 10 5 5.9 3.2 | 3.0 37.4 260 10 5 6.4 3.5
9500 1.5 34.7 255 9 4 5.8 3.2 | 3.5 38.3 260 9 5 7.7 4.2
9250 2.0 35.6 250 7 4 5.7 3.1 | 4.0 39.2 255 8 4 5.5 3.0
9000 2.4 36.3 245 7 3 5.3 2.9 | 4.4 39.9 255 7 4 5.9 3.3
8750 2.8 37.0 240 6 3 5.5 3.0 | 5.0 41.0 255 6 3 8.8 4.8
8500 3.2 37.8 230 5 3 5.9 3.3 | 5.6 42.1 255 5 3 9.2 5.0
8250 3.9 39.0 205 4 2 4.3 2.4 | 6.3 43.3 250 4 2 7.5 4.1
8000 4.3 39.7 195 3 2 5.7 3.1 | 7.3 45.1 255 3 2 9.3 5.1
7750 4.8 40.6 180 3 2 7.4 4.0 | 8.1 46.6 255 3 2 11.7 6.4
7500 5.3 41.5 165 3 1 5.2 2.9 | 8.9 48.0 255 3 1 8.9 4.9
7250 5.5 41.9 145 2 1 2.7 1.5 | 9.4 48.9 255 2 1 6.3 3.5
7000 5.8 42.4 120 2 1 7.5 4.1 | 10.0 50.0 260 2 1 10.8 5.9
6750 6.6 43.9 105 2 1 10.7 5.9 | 11.0 51.8 260 2 1 13.2 7.2
6500 7.3 45.1 095 2 1 8.7 4.8 | 11.8 53.2 260 2 1 10.4 5.7
6250 7.9 46.2 090 3 1 8.3 4.6 | 12.6 54.7 265 2 1 9.9 5.5
6000 8.5 47.3 085 3 1 9.3 5.1 | 13.3 55.9 270 2 1 8.9 4.9
5750 9.4 48.9 090 2 1 15.6 8.6 | 14.1 57.4 265 2 1 15.2 8.4
5500 11.1 52.0 085 3 1 34.2 18.7 | 16.8 62.2 280 2 1 71.3 39.1
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
05/24/2024 at 1500 MDT | 05/24/2024 at 1800 MDT
|
CAPE... 0.0 LI... +1.4 | CAPE... 0.0 LI... +1.0
CINH... -0.0 K Index... +17.7 | CINH... -0.3 K Index... +18.9
|
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 -56.1 -69.0 260 59 30 0.6 0.3 | -56.4 -69.5 260 60 31 1.3 0.7
45000 -55.4 -67.7 260 76 39 -0.8 -0.4 | -54.8 -66.6 260 76 39 -0.9 -0.5
40000 -56.5 -69.7 260 85 44 -0.7 -0.4 | -56.1 -69.0 260 84 43 -0.9 -0.5
38000 -55.0 -67.0 260 84 43 4.2 2.3 | -54.6 -66.3 255 81 42 4.0 2.2
36000 -52.2 -62.0 260 80 41 4.2 2.3 | -51.9 -61.4 255 73 38 4.0 2.2
34000 -48.8 -55.8 260 77 40 7.8 4.3 | -48.7 -55.7 255 68 35 7.3 4.0
32000 -44.1 -47.4 260 75 38 7.8 4.3 | -44.4 -47.9 255 64 33 7.3 4.0
30000 -39.4 -38.9 260 71 37 8.1 4.4 | -39.8 -39.6 260 61 31 8.2 4.5
29000 -37.0 -34.6 260 69 36 8.1 4.4 | -37.3 -35.1 260 61 31 8.2 4.5
28000 -34.6 -30.3 260 67 35 8.1 4.4 | -34.9 -30.8 260 60 31 8.3 4.5
27000 -32.2 -26.0 260 65 33 7.1 3.9 | -32.5 -26.5 260 59 31 7.4 4.1
26000 -30.1 -22.2 260 62 32 7.1 3.9 | -30.3 -22.5 260 59 30 7.4 4.1
25000 -28.0 -18.4 260 59 31 7.1 3.9 | -28.1 -18.6 260 58 30 7.4 4.1
24000 -25.9 -14.6 260 56 29 6.3 3.4 | -25.9 -14.6 255 57 29 7.0 3.8
23000 -24.3 -11.7 260 52 27 5.4 3.0 | -23.4 -10.1 255 52 27 6.6 3.6
22000 -22.3 -8.1 260 47 24 5.4 3.0 | -21.5 -6.7 255 49 25 6.6 3.6
21000 -20.6 -5.1 260 43 22 6.3 3.5 | -19.5 -3.1 250 46 24 6.3 3.5
20000 -18.7 -1.7 255 40 20 6.3 3.4 | -17.7 0.1 245 42 22 6.4 3.5
19500 -17.8 -0.0 255 38 19 6.3 3.4 | -16.7 1.9 245 40 21 6.4 3.5
19000 -16.8 1.8 255 36 19 6.2 3.4 | -15.8 3.6 240 39 20 6.3 3.4
18500 -15.9 3.4 255 34 18 7.2 4.0 | -14.8 5.4 235 37 19 7.5 4.1
18000 -14.8 5.4 255 33 17 7.2 3.9 | -13.7 7.3 235 36 19 7.4 4.1
17500 -13.8 7.2 250 32 16 7.3 4.0 | -12.6 9.3 230 35 18 7.7 4.2
17000 -12.7 9.1 250 31 16 7.5 4.1 | -11.4 11.5 225 34 17 7.9 4.3
16500 -11.6 11.1 250 30 16 7.5 4.1 | -10.3 13.5 225 32 16 7.9 4.4
16000 -10.4 13.3 245 29 15 7.7 4.2 | -9.1 15.6 220 30 15 8.0 4.4
15500 -9.3 15.3 245 28 14 7.6 4.2 | -7.9 17.8 220 27 14 8.0 4.4
15000 -8.2 17.2 245 27 14 8.2 4.5 | -6.7 19.9 220 25 13 8.1 4.4
14500 -6.9 19.6 245 26 13 8.2 4.5 | -5.5 22.1 220 23 12 8.1 4.4
14000 -5.7 21.7 240 24 12 8.7 4.8 | -4.3 24.3 215 21 11 8.5 4.7
13500 -4.4 24.1 240 23 12 8.8 4.8 | -3.0 26.6 215 19 10 8.7 4.8
13000 -3.0 26.6 240 21 11 8.8 4.8 | -1.7 28.9 215 18 9 8.6 4.7
12500 -1.7 28.9 240 20 10 8.8 4.8 | -0.4 31.3 215 16 8 8.6 4.7
12000 -0.4 31.3 240 18 9 8.8 4.9 | 0.8 33.4 215 14 7 8.7 4.8
11500 0.9 33.6 240 17 9 8.9 4.9 | 2.2 36.0 215 13 6 9.0 4.9
11000 2.3 36.1 240 15 8 8.1 4.4 | 3.5 38.3 220 11 6 8.5 4.6
10500 3.3 37.9 240 14 7 6.4 3.5 | 4.7 40.5 220 10 5 6.9 3.8
10250 3.9 39.0 245 13 7 10.1 5.5 | 5.2 41.4 220 9 5 9.4 5.2
10000 4.8 40.6 245 11 6 10.7 5.9 | 6.1 43.0 220 8 4 10.8 5.9
9750 5.4 41.7 245 10 5 7.3 4.0 | 6.8 44.2 225 7 4 8.8 4.8
9500 5.9 42.6 250 9 5 7.3 4.0 | 7.4 45.3 225 7 3 8.7 4.7
9250 6.5 43.7 255 9 4 9.4 5.1 | 8.1 46.6 230 6 3 9.2 5.0
9000 7.3 45.1 255 8 4 10.1 5.5 | 8.8 47.8 230 5 3 9.6 5.3
8750 8.0 46.4 255 7 4 8.3 4.5 | 9.5 49.1 235 5 2 9.2 5.0
8500 8.6 47.5 260 6 3 8.9 4.9 | 10.9 51.6 250 4 2 8.8 4.8
8250 9.9 49.8 275 6 3 8.4 4.6 | 11.5 52.7 260 3 2 7.8 4.3
8000 10.6 51.1 275 6 3 10.1 5.6 | 12.1 53.8 270 3 2 8.4 4.6
7750 11.4 52.5 275 5 3 11.2 6.1 | 12.8 55.0 275 3 2 9.5 5.2
7500 12.2 54.0 275 5 3 9.3 5.1 | 13.5 56.3 280 3 2 8.8 4.8
7250 12.8 55.0 285 5 3 7.2 3.9 | 14.1 57.4 290 4 2 8.1 4.5
7000 13.4 56.1 290 5 3 10.3 5.6 | 14.7 58.5 295 4 2 9.6 5.3
6750 14.3 57.7 285 5 2 12.5 6.9 | 15.5 59.9 295 4 2 10.9 6.0
6500 15.1 59.2 285 4 2 10.7 5.9 | 16.3 61.3 295 3 2 10.4 5.7
6250 15.9 60.6 295 5 2 10.5 5.8 | 17.1 62.8 300 4 2 10.9 6.0
6000 16.7 62.1 300 5 2 8.3 4.6 | 17.9 64.2 300 4 2 8.6 4.7
5750 17.3 63.1 290 4 2 13.6 7.4 | 18.5 65.3 300 4 2 10.0 5.5
5500 20.2 68.4 310 4 2 80.4 44.1 | 20.3 68.5 305 4 2 50.5 27.7
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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