Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
383
UXUS97 KGJT 201307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Monday, May 20, 2024
This forecast is for Monday, May 20, 2024:
If the trigger temperature of 72.7 F/22.6 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1670 ft/min (8.5 m/s)
Maximum height of thermals.................. 22517 ft MSL (17678 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 0845 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................. 20442 ft MSL (15602 ft AGL)
Thermal soaring outlook for Tuesday 05/21...... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:56:17 / 20:25:11 MDT
Total possible sunshine........... 14 hr 28 min 54 sec (868 min 54 sec)
Altitude of sun at 13:10:44 MDT... 70.94 degrees
Upper air data from rawinsonde observation taken on 05/20/2024 at 0600 MDT
Freezing level.................. 12927 ft MSL (8088 ft AGL)
Convective condensation level... 16729 ft MSL (11890 ft AGL)
Lifted condensation level....... 19143 ft MSL (14304 ft AGL)
Lifted index.................... -3.0
K index......................... +18.8
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 -53.0 -63.4 240 61 31 -1.8 -1.0 109.2 228.5 45.0 M M
45000 -52.6 -62.7 240 61 31 -7.8 -4.3 85.3 185.5 33.4 M M
40000 -54.7 -66.5 255 101 52 -0.1 -0.0 59.0 138.2 18.3 M M
38000 -53.1 -63.6 255 96 50 4.6 2.5 52.6 126.6 14.5 M M
36000 -50.3 -58.5 255 98 51 5.2 2.8 48.0 118.4 11.7 M M
34000 -46.6 -51.9 250 93 48 4.9 2.7 43.9 111.1 9.2 M M
32000 -43.0 -45.4 250 72 37 4.6 2.5 40.8 105.4 7.1 M M
30000 -39.9 -39.8 240 53 27 6.7 3.7 37.1 98.7 4.5 M M
29000 -37.9 -36.2 240 53 27 7.2 4.0 35.8 96.5 3.6 M M
28000 -35.8 -32.4 235 48 25 7.2 3.9 34.8 94.7 2.9 M M
27000 -33.6 -28.5 235 50 26 8.2 4.5 33.9 93.0 2.2 M M
26000 -31.0 -23.8 240 54 28 9.1 5.0 33.4 92.1 1.8 M M
25000 -28.7 -19.7 240 51 26 7.7 4.2 32.6 90.7 1.2 M M
24000 -26.2 -15.2 240 49 25 9.3 5.1 32.2 89.9 0.8 M M
23000 -23.6 -10.5 240 52 27 8.9 4.9 31.8 89.2 0.5 M M
22000 -21.9 -7.4 230 49 25 4.2 2.3 30.3 86.5 -0.8 1641 8.3
21000 -20.1 -4.2 230 49 25 6.8 3.7 28.9 84.1 -1.9 1556 7.9
20000 -18.7 -1.7 220 42 21 7.9 4.3 27.2 81.0 -3.5 1486 7.5
19500 -17.7 0.1 215 40 21 7.2 4.0 26.7 80.1 -3.9 1440 7.3
19000 -16.1 3.0 205 39 20 7.7 4.2 26.1 78.9 -4.6 1371 7.0
18500 -14.9 5.2 205 38 20 9.1 5.0 25.9 78.6 -4.8 1318 6.7
18000 -13.5 7.7 215 37 19 9.0 5.0 25.8 78.4 -4.9 1263 6.4
17500 -12.2 10.0 215 37 19 9.0 5.0 25.7 78.2 -5.1 1208 6.1
17000 -10.8 12.6 225 32 16 9.0 5.0 25.5 78.0 -5.2 1153 5.9
16500 -9.5 14.9 225 32 16 9.0 5.0 25.4 77.8 -5.4 1098 5.6
16000 -8.1 17.4 225 32 16 9.2 5.0 25.3 77.5 -5.5 1043 5.3
15500 -6.9 19.6 235 29 15 7.3 4.0 25.0 77.0 -5.8 991 5.0
15000 -5.6 21.9 245 27 14 9.5 5.2 24.8 76.7 -6.0 938 4.8
14500 -4.3 24.3 240 26 13 9.4 5.1 24.8 76.6 -6.1 882 4.5
14000 -2.9 26.8 235 25 13 9.3 5.1 24.7 76.5 -6.2 826 4.2
13500 -1.5 29.3 240 23 12 9.4 5.1 24.6 76.3 -6.4 770 3.9
13000 -0.1 31.8 235 23 12 9.1 5.0 24.6 76.2 -6.5 713 3.6
12500 1.2 34.2 235 25 13 9.0 5.0 24.5 76.0 -6.6 658 3.3
12000 2.6 36.7 235 25 13 9.0 5.0 24.4 75.8 -6.8 603 3.1
11500 3.9 39.0 235 27 14 9.0 5.0 24.2 75.6 -6.9 548 2.8
11000 5.3 41.5 240 25 13 9.0 5.0 24.1 75.4 -7.1 492 2.5
10500 6.6 43.9 245 24 12 9.1 5.0 24.0 75.2 -7.2 437 2.2
10250 7.3 45.1 250 23 12 9.2 5.0 24.5 75.1 -7.3 410 2.1
10000 7.9 46.2 250 23 12 8.3 4.6 23.9 75.0 -7.4 384 2.0
9750 8.5 47.3 250 22 11 7.6 4.2 23.7 74.7 -7.6 359 1.8
9500 9.1 48.4 245 21 11 7.8 4.3 23.6 74.5 -7.8 334 1.7
9250 9.7 49.5 245 19 10 7.8 4.3 23.5 74.2 -7.9 309 1.6
9000 10.3 50.5 240 18 9 7.8 4.3 23.3 74.0 -8.0 284 1.4
8750 10.8 51.4 240 18 9 7.8 4.3 23.2 73.7 -8.2 259 1.3
8500 11.4 52.5 245 16 8 7.8 4.3 23.0 73.5 -8.4 234 1.2
8250 12.0 53.6 245 14 7 7.8 4.3 22.9 73.2 -8.5 209 1.1
8000 12.6 54.7 240 12 6 7.8 4.3 22.7 72.9 -8.7 184 0.9
7750 13.2 55.8 240 12 6 7.8 4.3 22.6 72.7 -8.8 159 0.8
7500 13.8 56.8 230 10 5 7.8 4.3 22.4 72.4 -9.0 134 0.7
7250 14.4 57.9 215 8 4 7.8 4.3 22.3 72.1 -9.2 109 0.6
7000 14.9 58.8 195 6 3 7.8 4.3 22.1 71.8 -9.3 84 0.4
6750 15.5 59.9 190 7 3 7.8 4.3 22.0 71.6 -9.5 59 0.3
6500 16.1 61.0 170 6 3 7.8 4.3 21.8 71.3 -9.7 34 0.2
6250 16.7 62.1 145 9 5 7.7 4.2 21.7 71.0 -9.9 10 0.0
6000 17.3 63.1 130 12 6 8.2 4.5 21.5 70.7 -10.0 M M
5750 17.8 64.0 130 13 7 2.1 1.2 21.3 70.3 -10.3 M M
5500 17.8 64.0 125 14 7 4.3 2.3 20.6 69.0 -11.1 M M
5250 18.3 64.9 120 15 8 8.5 4.6 20.5 68.9 -11.3 M M
5000 18.1 64.6 120 15 8 -19.7 -10.8 19.6 67.2 -12.3 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/20/2024 at 0900 MDT | 05/20/2024 at 1200 MDT
|
CAPE... 0.0 LI... +1.5 | CAPE... +25.6 LI... +0.5
CINH... 0.0 K Index... +15.2 | CINH... -2.7 K Index... +18.0
|
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 -54.0 -65.2 240 50 26 1.9 1.0 | -54.6 -66.3 235 54 28 1.9 1.0
45000 -51.7 -61.1 245 61 31 -1.0 -0.6 | -52.1 -61.8 235 64 33 -0.3 -0.2
40000 -53.4 -64.1 250 91 47 -1.1 -0.6 | -52.7 -62.9 245 88 45 -0.3 -0.2
38000 -52.2 -62.0 250 97 50 3.5 1.9 | -51.5 -60.7 245 96 49 3.1 1.7
36000 -49.8 -57.6 245 98 51 3.5 1.9 | -49.4 -56.9 240 103 53 3.1 1.7
34000 -47.1 -52.8 245 97 50 6.1 3.4 | -46.9 -52.4 240 105 54 5.7 3.1
32000 -43.4 -46.1 245 92 48 6.1 3.4 | -43.5 -46.3 240 101 52 5.7 3.1
30000 -39.7 -39.5 245 84 43 6.4 3.5 | -40.0 -40.0 240 93 48 6.4 3.5
29000 -37.8 -36.0 245 78 40 6.4 3.5 | -38.0 -36.4 235 85 44 6.4 3.5
28000 -35.9 -32.6 245 71 37 6.4 3.5 | -36.1 -33.0 235 77 40 6.4 3.5
27000 -34.0 -29.2 245 66 34 7.3 4.0 | -34.2 -29.6 235 69 36 7.1 3.9
26000 -31.8 -25.2 245 64 33 7.3 4.0 | -32.0 -25.6 235 65 34 7.3 4.0
25000 -29.6 -21.3 245 62 32 7.3 4.0 | -29.8 -21.6 230 61 32 7.3 4.0
24000 -27.4 -17.3 240 60 31 7.9 4.3 | -27.7 -17.9 230 58 30 7.9 4.3
23000 -24.3 -11.7 240 57 29 8.3 4.6 | -25.1 -13.2 230 57 29 8.5 4.7
22000 -21.8 -7.2 240 55 28 8.3 4.6 | -22.0 -7.6 230 55 28 8.5 4.7
21000 -19.5 -3.1 235 52 27 6.9 3.8 | -19.7 -3.5 230 53 27 6.2 3.4
20000 -17.4 0.7 235 48 25 7.0 3.8 | -17.8 -0.0 225 48 25 6.4 3.5
19500 -16.4 2.5 235 46 24 7.0 3.8 | -16.9 1.6 225 45 23 6.4 3.5
19000 -15.3 4.5 230 44 23 7.0 3.8 | -15.9 3.4 225 43 22 6.4 3.5
18500 -14.3 6.3 230 42 22 6.7 3.7 | -15.0 5.0 225 40 20 6.7 3.7
18000 -13.3 8.1 230 40 21 6.8 3.7 | -14.0 6.8 225 37 19 6.8 3.7
17500 -12.3 9.9 225 39 20 6.9 3.8 | -13.0 8.6 225 34 17 7.3 4.0
17000 -11.3 11.7 225 37 19 7.0 3.9 | -11.9 10.6 220 32 16 7.8 4.3
16500 -10.3 13.5 225 36 18 7.2 3.9 | -10.8 12.6 220 29 15 7.9 4.3
16000 -9.2 15.4 220 34 18 8.1 4.4 | -9.5 14.9 220 28 15 8.9 4.9
15500 -8.0 17.6 220 33 17 8.0 4.4 | -8.2 17.2 215 27 14 8.8 4.8
15000 -6.8 19.8 220 31 16 8.7 4.7 | -6.9 19.6 215 27 14 9.3 5.1
14500 -5.5 22.1 220 30 15 8.7 4.8 | -5.5 22.1 215 26 13 9.3 5.1
14000 -4.2 24.4 220 29 15 8.8 4.8 | -4.1 24.6 215 26 13 9.4 5.1
13500 -2.9 26.8 220 28 14 8.8 4.8 | -2.7 27.1 215 25 13 9.4 5.2
13000 -1.6 29.1 220 27 14 8.9 4.9 | -1.3 29.7 215 25 13 9.4 5.2
12500 -0.3 31.5 225 26 13 9.0 4.9 | 0.1 32.2 215 24 12 9.5 5.2
12000 1.0 33.8 225 25 13 9.0 4.9 | 1.6 34.9 215 23 12 9.5 5.2
11500 2.3 36.1 225 24 12 9.0 4.9 | 3.0 37.4 215 23 12 9.5 5.2
11000 3.7 38.7 225 23 12 8.4 4.6 | 4.4 39.9 215 22 12 9.2 5.0
10500 4.8 40.6 225 22 11 6.8 3.7 | 5.7 42.3 220 21 11 7.9 4.4
10250 5.4 41.7 230 21 11 10.2 5.6 | 6.3 43.3 220 21 11 10.4 5.7
10000 6.3 43.3 225 21 11 11.4 6.3 | 7.2 45.0 215 21 11 11.7 6.4
9750 6.9 44.4 230 20 10 8.3 4.6 | 8.0 46.4 215 21 11 9.9 5.4
9500 7.6 45.7 230 20 10 8.1 4.5 | 8.7 47.7 220 21 11 9.9 5.5
9250 8.2 46.8 230 19 10 9.4 5.2 | 9.5 49.1 220 21 11 9.9 5.4
9000 8.9 48.0 225 18 9 9.5 5.2 | 10.2 50.4 215 21 11 9.9 5.5
8750 9.5 49.1 225 17 9 7.9 4.3 | 11.0 51.8 215 21 11 10.0 5.5
8500 10.7 51.3 225 16 8 7.8 4.3 | 11.7 53.1 215 21 11 10.0 5.5
8250 11.3 52.3 225 15 7 7.1 3.9 | 13.2 55.8 215 20 10 10.0 5.5
8000 11.8 53.2 225 13 7 7.5 4.1 | 14.0 57.2 220 20 10 10.1 5.5
7750 12.4 54.3 220 12 6 8.5 4.6 | 14.7 58.5 215 19 10 10.3 5.6
7500 13.0 55.4 215 11 6 7.2 4.0 | 15.5 59.9 215 19 10 9.8 5.4
7250 13.5 56.3 210 10 5 5.3 2.9 | 16.2 61.2 215 19 10 8.7 4.7
7000 13.9 57.0 210 9 5 7.5 4.1 | 16.8 62.2 220 19 10 9.9 5.4
6750 14.6 58.3 205 9 5 9.5 5.2 | 17.6 63.7 215 18 9 11.1 6.1
6500 15.3 59.5 200 9 5 9.2 5.0 | 18.4 65.1 215 18 9 10.9 6.0
6250 16.0 60.8 195 8 4 10.0 5.5 | 19.3 66.7 215 17 9 12.2 6.7
6000 16.7 62.1 195 7 4 8.4 4.6 | 20.2 68.4 220 17 9 8.7 4.8
5750 17.3 63.1 190 7 4 11.6 6.4 | 20.8 69.4 215 16 8 13.4 7.3
5500 19.3 66.7 185 5 3 49.9 27.4 | 23.9 75.0 220 14 7 89.0 48.8
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
05/20/2024 at 1500 MDT | 05/20/2024 at 1800 MDT
|
CAPE... +32.3 LI... -0.1 | CAPE... +5.7 LI... +0.2
CINH... -7.6 K Index... +10.5 | CINH... -12.5 K Index... +12.3
|
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 -54.0 -65.2 235 52 27 2.1 1.2 | -52.4 -62.3 240 44 23 2.2 1.2
45000 -51.2 -60.2 230 66 34 -0.4 -0.2 | -49.5 -57.1 240 60 31 -0.3 -0.2
40000 -52.0 -61.6 235 85 44 -0.5 -0.3 | -50.1 -58.2 235 73 38 -0.4 -0.2
38000 -51.1 -60.0 235 94 49 2.6 1.4 | -50.6 -59.1 230 78 40 -1.2 -0.6
36000 -49.4 -56.9 235 107 55 2.6 1.4 | -51.4 -60.5 230 82 42 -1.2 -0.6
34000 -47.3 -53.1 235 112 58 5.2 2.8 | -50.6 -59.1 230 84 43 7.0 3.8
32000 -44.2 -47.6 235 105 54 5.2 2.8 | -46.4 -51.5 225 83 43 7.1 3.9
30000 -40.8 -41.4 230 98 50 6.8 3.7 | -42.0 -43.6 225 80 41 7.9 4.3
29000 -38.7 -37.7 235 92 48 6.8 3.7 | -39.6 -39.3 225 77 39 7.9 4.3
28000 -36.7 -34.1 235 87 45 6.8 3.8 | -37.3 -35.1 230 73 38 7.9 4.3
27000 -34.7 -30.5 235 82 42 6.7 3.7 | -34.9 -30.8 230 69 36 7.4 4.1
26000 -32.7 -26.9 230 74 38 6.7 3.7 | -32.8 -27.0 230 63 32 7.2 4.0
25000 -30.7 -23.3 230 66 34 6.7 3.7 | -30.6 -23.1 230 57 29 7.3 4.0
24000 -28.7 -19.7 230 59 30 6.9 3.8 | -28.5 -19.3 230 51 26 7.4 4.1
23000 -26.6 -15.9 230 54 28 7.2 3.9 | -26.2 -15.2 230 47 24 7.7 4.2
22000 -23.9 -11.0 225 48 25 7.3 4.0 | -23.4 -10.1 225 42 22 7.7 4.2
21000 -21.6 -6.9 225 44 22 8.9 4.9 | -21.0 -5.8 225 39 20 8.0 4.4
20000 -19.0 -2.2 225 39 20 8.8 4.8 | -18.7 -1.7 225 36 19 8.0 4.4
19500 -17.7 0.1 225 37 19 8.8 4.8 | -17.5 0.5 225 35 18 8.0 4.4
19000 -16.4 2.5 220 35 18 8.8 4.8 | -16.3 2.7 225 34 18 8.0 4.4
18500 -15.1 4.8 220 34 17 8.9 4.9 | -15.1 4.8 225 33 17 8.2 4.5
18000 -13.8 7.2 220 33 17 8.9 4.9 | -13.9 7.0 225 33 17 8.3 4.5
17500 -12.5 9.5 220 33 17 9.2 5.0 | -12.7 9.1 225 32 17 8.6 4.7
17000 -11.0 12.2 220 32 17 9.5 5.2 | -11.3 11.7 225 32 16 9.2 5.0
16500 -9.6 14.7 220 32 16 9.5 5.2 | -10.0 14.0 225 32 16 9.2 5.0
16000 -8.2 17.2 220 32 16 9.4 5.2 | -8.6 16.5 225 31 16 9.6 5.3
15500 -6.8 19.8 215 31 16 9.4 5.2 | -7.1 19.2 225 31 16 9.5 5.2
15000 -5.4 22.3 215 31 16 9.5 5.2 | -5.7 21.7 225 31 16 9.7 5.3
14500 -4.0 24.8 215 30 16 9.5 5.2 | -4.2 24.4 225 31 16 9.8 5.4
14000 -2.5 27.5 215 30 15 9.5 5.2 | -2.8 27.0 225 30 16 9.8 5.4
13500 -1.1 30.0 215 30 15 9.6 5.2 | -1.3 29.7 225 30 16 9.9 5.4
13000 0.3 32.5 215 29 15 9.6 5.3 | 0.2 32.4 225 30 15 9.8 5.4
12500 1.8 35.2 215 29 15 9.6 5.3 | 1.6 34.9 230 30 15 9.8 5.4
12000 3.2 37.8 215 29 15 9.6 5.3 | 3.1 37.6 230 29 15 9.8 5.4
11500 4.6 40.3 215 28 15 9.6 5.3 | 4.5 40.1 230 29 15 9.7 5.3
11000 6.1 43.0 215 28 14 9.4 5.2 | 6.0 42.8 230 28 14 9.6 5.3
10500 7.4 45.3 215 27 14 8.2 4.5 | 7.3 45.1 235 27 14 7.8 4.3
10250 8.0 46.4 215 26 14 10.7 5.9 | 7.9 46.2 235 27 14 10.4 5.7
10000 8.9 48.0 215 27 14 11.8 6.5 | 8.8 47.8 235 27 14 11.9 6.5
9750 9.7 49.5 215 27 14 9.9 5.5 | 9.6 49.3 235 27 14 10.0 5.5
9500 10.5 50.9 215 26 13 9.5 5.2 | 10.3 50.5 235 26 14 9.2 5.1
9250 11.2 52.2 215 26 13 9.7 5.3 | 11.0 51.8 235 26 13 9.7 5.3
9000 11.9 53.4 215 26 13 9.9 5.4 | 11.8 53.2 235 26 13 10.1 5.5
8750 12.7 54.9 215 26 13 10.2 5.6 | 12.5 54.5 235 26 13 9.8 5.4
8500 13.4 56.1 215 25 13 10.1 5.6 | 13.2 55.8 235 25 13 9.6 5.2
8250 14.9 58.8 215 24 13 9.6 5.3 | 14.7 58.5 235 25 13 9.8 5.4
8000 15.6 60.1 215 24 12 9.5 5.2 | 15.4 59.7 235 24 12 9.9 5.4
7750 16.4 61.5 215 24 12 10.1 5.5 | 16.1 61.0 235 23 12 9.5 5.2
7500 17.1 62.8 215 23 12 10.0 5.5 | 16.9 62.4 235 22 12 10.2 5.6
7250 17.8 64.0 215 23 12 8.8 4.8 | 17.6 63.7 235 22 11 7.9 4.3
7000 18.5 65.3 215 23 12 9.4 5.2 | 18.1 64.6 240 22 11 8.4 4.6
6750 19.3 66.7 215 22 11 10.9 6.0 | 18.9 66.0 240 21 11 11.1 6.1
6500 20.1 68.2 215 21 11 10.8 5.9 | 19.7 67.5 240 19 10 10.4 5.7
6250 20.9 69.6 215 21 11 11.2 6.2 | 20.5 68.9 240 19 10 10.2 5.6
6000 21.9 71.4 210 20 10 16.5 9.0 | 21.2 70.2 240 19 10 11.4 6.3
5750 23.4 74.1 210 18 10 25.4 13.9 | 22.2 72.0 240 17 9 14.5 8.0
5500 25.0 77.0 210 17 9 9.5 5.2 | 23.1 73.6 240 14 7 8.7 4.8
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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