Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
877
UXUS97 KGJT 231307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Thursday, May 23, 2024
This forecast is for Thursday, May 23, 2024:
If the trigger temperature of 71.2 F/21.8 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1267 ft/min (6.4 m/s)
Maximum height of thermals.................. 17878 ft MSL (13039 ft AGL)
Forecast maximum temperature................... 76.0 F/24.9 C
Time of trigger temperature.................... 1045 MDT
Time of overdevelopment........................ 1400 MDT
Middle/high clouds during soaring window....... None
Surface winds during soaring window............ 20 mph or less
Height of the -3 thermal index................. 7748 ft MSL (2909 ft AGL)
Thermal soaring outlook for Friday 05/24....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 05:54:14 / 20:27:43 MDT
Total possible sunshine........... 14 hr 33 min 29 sec (873 min 29 sec)
Altitude of sun at 13:10:58 MDT... 71.51 degrees
Upper air data from rawinsonde observation taken on 05/23/2024 at 0600 MDT
Freezing level.................. 12420 ft MSL (7581 ft AGL)
Convective condensation level... 20863 ft MSL (16024 ft AGL)
Lifted condensation level....... 18806 ft MSL (13967 ft AGL)
Lifted index.................... +3.0
K index......................... +8.9
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 -55.3 -67.5 245 60 31 4.0 2.2 107.7 225.8 47.6 M M
45000 -55.6 -68.1 260 48 25 2.5 1.4 82.4 180.3 35.5 M M
40000 -56.3 -69.3 260 70 36 -5.1 -2.8 57.2 135.0 21.5 M M
38000 -57.6 -71.7 260 72 37 4.4 2.4 46.5 115.8 14.9 M M
36000 -54.8 -66.6 260 56 29 4.7 2.6 42.0 107.6 12.2 M M
34000 -50.9 -59.6 255 55 28 6.6 3.6 39.2 102.6 10.5 M M
32000 -47.0 -52.6 250 48 25 8.5 4.7 36.6 97.8 8.9 M M
30000 -42.1 -43.8 260 48 25 6.2 3.4 34.4 93.9 7.4 M M
29000 -39.6 -39.3 260 48 25 8.9 4.9 33.8 92.9 7.1 M M
28000 -37.0 -34.6 255 46 24 8.9 4.9 33.6 92.4 7.0 M M
27000 -34.3 -29.7 255 48 25 8.9 4.9 33.2 91.8 6.8 M M
26000 -31.6 -24.9 260 48 25 8.9 4.9 32.8 91.1 6.6 M M
25000 -29.1 -20.4 260 48 25 7.7 4.2 32.3 90.2 6.3 M M
24000 -26.8 -16.2 260 42 22 7.4 4.1 31.6 88.8 5.7 M M
23000 -24.2 -11.6 255 45 23 9.3 5.1 31.2 88.2 5.5 M M
22000 -21.4 -6.5 250 44 23 9.3 5.1 31.1 87.9 5.4 M M
21000 -18.6 -1.5 255 48 25 9.2 5.1 30.9 87.6 5.3 M M
20000 -16.6 2.1 255 51 26 4.3 2.3 29.7 85.5 4.4 M M
19500 -16.0 3.2 250 46 24 4.1 2.3 28.7 83.6 3.6 M M
19000 -15.4 4.3 250 42 21 4.2 2.3 27.7 81.9 2.7 M M
18500 -14.9 5.2 245 38 19 0.3 0.2 26.7 80.0 1.8 M M
18000 -15.0 5.0 240 35 18 4.5 2.5 24.9 76.9 0.2 M M
17500 -14.1 6.6 240 31 16 6.1 3.3 24.4 75.9 -0.3 1244 6.3
17000 -13.0 8.6 245 30 16 8.9 4.9 24.0 75.1 -0.7 1198 6.1
16500 -11.0 12.2 250 29 15 9.1 5.0 23.9 75.0 -0.8 1114 5.7
16000 -9.6 14.7 255 29 15 9.1 5.0 23.8 74.9 -0.8 1059 5.4
15500 -8.3 17.1 255 29 15 9.1 5.0 23.8 74.8 -0.9 1003 5.1
15000 -6.9 19.6 255 29 15 9.1 5.0 23.7 74.6 -1.0 947 4.8
14500 -5.5 22.1 260 29 15 9.1 5.0 23.6 74.5 -1.1 892 4.5
14000 -4.2 24.4 255 26 13 9.1 5.0 23.5 74.3 -1.1 836 4.2
13500 -2.8 27.0 250 28 14 9.1 5.0 23.4 74.1 -1.3 780 4.0
13000 -1.5 29.3 255 31 16 9.1 5.0 23.3 73.9 -1.4 725 3.7
12500 -0.1 31.8 255 31 16 9.1 5.0 23.2 73.7 -1.5 669 3.4
12000 1.3 34.3 250 31 16 9.1 5.0 23.1 73.5 -1.6 613 3.1
11500 2.6 36.7 250 31 16 9.1 5.0 22.9 73.3 -1.7 558 2.8
11000 4.0 39.2 255 32 16 9.1 5.0 22.8 73.0 -1.9 502 2.6
10500 5.4 41.7 255 29 15 9.1 5.0 22.7 72.8 -2.0 447 2.3
10250 6.0 42.8 250 28 14 9.2 5.0 22.6 72.6 -2.1 419 2.1
10000 6.7 44.1 240 27 14 8.9 4.9 22.5 72.5 -2.2 391 2.0
9750 7.4 45.3 240 26 13 8.6 4.7 22.4 72.3 -2.3 364 1.8
9500 8.0 46.4 240 25 13 8.6 4.7 22.3 72.2 -2.4 337 1.7
9250 8.7 47.7 235 24 12 8.6 4.7 22.2 72.0 -2.4 311 1.6
9000 9.3 48.7 235 23 12 8.6 4.7 22.2 71.9 -2.5 284 1.4
8750 9.9 49.8 230 22 11 8.6 4.7 22.1 71.7 -2.6 257 1.3
8500 10.6 51.1 230 21 11 8.6 4.7 22.0 71.6 -2.7 231 1.2
8250 11.2 52.2 225 21 11 8.6 4.7 21.9 71.4 -2.8 204 1.0
8000 11.9 53.4 220 20 10 8.6 4.7 21.8 71.3 -2.9 177 0.9
7750 12.5 54.5 220 20 10 8.6 4.7 21.7 71.1 -3.0 151 0.8
7500 13.2 55.8 215 20 10 8.6 4.7 21.6 70.9 -3.1 124 0.6
7250 13.8 56.8 210 20 10 8.6 4.7 21.5 70.7 -3.2 97 0.5
7000 14.5 58.1 200 20 10 8.6 4.7 21.4 70.6 -3.3 71 0.4
6750 15.0 59.0 195 18 9 6.8 3.7 21.3 70.3 -3.4 46 0.2
6500 15.3 59.5 185 17 9 -1.6 -0.9 20.8 69.4 -3.9 31 0.2
6250 15.1 59.2 175 15 8 1.5 0.8 19.8 67.7 -4.9 30 0.2
6000 15.6 60.1 165 16 8 7.5 4.1 19.6 67.3 -5.1 8 0.0
5750 16.0 60.8 165 17 9 9.1 5.0 19.4 66.9 -5.4 M M
5500 16.5 61.7 160 18 9 -2.9 -1.6 19.2 66.5 -5.7 M M
5250 15.4 59.7 155 16 8 -21.2 -11.7 17.3 63.2 -7.6 M M
5000 13.9 57.0 145 9 5 -13.5 -7.4 15.1 59.3 -9.8 29 0.1
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
05/23/2024 at 0900 MDT | 05/23/2024 at 1200 MDT
|
CAPE... 0.0 LI... +2.5 | CAPE... +1.3 LI... +1.4
CINH... 0.0 K Index... +15.1 | CINH... -2.1 K Index... +19.6
|
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 -67.2 255 46 23 1.2 0.7 | -54.6 -66.3 255 48 25 1.0 0.6
45000 -53.3 -63.9 260 58 30 -1.2 -0.7 | -53.2 -63.8 255 57 30 -0.6 -0.3
40000 -55.9 -68.6 260 70 36 -1.7 -0.9 | -54.5 -66.1 260 71 36 -0.9 -0.5
38000 -54.8 -66.6 255 72 37 3.8 2.1 | -54.0 -65.2 260 73 38 1.9 1.0
36000 -52.6 -62.7 255 73 37 3.8 2.1 | -52.9 -63.2 260 75 39 1.9 1.0
34000 -49.9 -57.8 255 72 37 6.4 3.5 | -50.9 -59.6 260 75 39 7.2 4.0
32000 -46.0 -50.8 255 68 35 6.5 3.6 | -46.5 -51.7 260 73 37 7.4 4.1
30000 -41.9 -43.4 255 65 33 7.5 4.1 | -42.0 -43.6 260 70 36 7.6 4.2
29000 -39.7 -39.5 255 63 32 7.6 4.2 | -39.7 -39.5 260 69 35 7.7 4.2
28000 -37.4 -35.3 255 61 32 7.6 4.2 | -37.4 -35.3 260 67 35 7.7 4.2
27000 -35.1 -31.2 255 60 31 7.8 4.3 | -35.1 -31.2 255 66 34 7.7 4.2
26000 -32.1 -25.8 255 57 29 8.0 4.4 | -32.2 -26.0 255 64 33 7.6 4.2
25000 -29.7 -21.5 255 55 28 8.0 4.4 | -30.0 -22.0 255 63 33 7.7 4.2
24000 -27.3 -17.1 255 53 27 7.6 4.2 | -27.7 -17.9 255 62 32 7.4 4.1
23000 -25.1 -13.2 250 51 26 7.4 4.1 | -25.5 -13.9 250 59 31 7.4 4.0
22000 -22.9 -9.2 250 49 25 7.4 4.1 | -23.3 -9.9 250 57 29 7.4 4.0
21000 -20.7 -5.3 250 47 24 6.7 3.7 | -21.1 -6.0 250 55 28 7.1 3.9
20000 -18.7 -1.7 245 45 23 6.8 3.7 | -19.0 -2.2 245 52 27 7.1 3.9
19500 -17.7 0.1 245 44 23 6.8 3.7 | -18.0 -0.4 245 51 26 7.1 3.9
19000 -16.7 1.9 245 43 22 6.8 3.7 | -16.9 1.6 245 50 26 7.1 3.9
18500 -15.7 3.7 245 42 22 6.8 3.7 | -15.9 3.4 245 48 25 7.1 3.9
18000 -14.7 5.5 245 42 21 6.9 3.8 | -14.8 5.4 245 48 25 7.1 3.9
17500 -13.7 7.3 240 41 21 7.1 3.9 | -13.8 7.2 245 47 24 7.2 3.9
17000 -12.6 9.3 240 40 21 7.8 4.3 | -12.7 9.1 240 46 24 7.5 4.1
16500 -11.5 11.3 240 39 20 7.7 4.2 | -11.6 11.1 240 45 23 7.4 4.1
16000 -10.3 13.5 240 38 20 8.2 4.5 | -10.5 13.1 240 43 22 8.2 4.5
15500 -9.1 15.6 240 38 19 8.2 4.5 | -9.3 15.3 240 42 21 8.1 4.5
15000 -7.9 17.8 240 37 19 8.2 4.5 | -8.1 17.4 240 40 21 7.9 4.4
14500 -6.7 19.9 240 36 19 8.2 4.5 | -6.9 19.6 240 38 20 7.8 4.3
14000 -5.4 22.3 240 36 18 8.1 4.5 | -5.7 21.7 240 37 19 7.8 4.3
13500 -4.2 24.4 245 35 18 8.0 4.4 | -4.6 23.7 240 35 18 7.8 4.3
13000 -3.0 26.6 245 34 17 8.0 4.4 | -3.4 25.9 240 33 17 7.8 4.3
12500 -1.8 28.8 245 33 17 8.0 4.4 | -2.3 27.9 240 32 17 7.9 4.3
12000 -0.6 30.9 245 32 16 7.9 4.4 | -1.1 30.0 245 32 16 7.9 4.3
11500 0.5 32.9 245 30 16 7.5 4.1 | 0.1 32.2 245 31 16 8.0 4.4
11000 1.6 34.9 250 29 15 7.4 4.1 | 1.3 34.3 245 29 15 7.8 4.3
10500 2.6 36.7 250 28 14 5.7 3.1 | 2.3 36.1 245 28 14 6.0 3.3
10250 3.1 37.6 250 27 14 7.6 4.2 | 2.8 37.0 245 28 14 8.8 4.8
10000 3.8 38.8 250 26 13 10.0 5.5 | 3.7 38.7 245 27 14 11.7 6.4
9750 4.5 40.1 250 24 12 8.3 4.6 | 4.4 39.9 245 26 13 9.4 5.1
9500 5.0 41.0 250 23 12 7.2 3.9 | 5.1 41.2 250 26 13 8.2 4.5
9250 6.2 43.2 250 21 11 8.8 4.9 | 5.7 42.3 250 25 13 8.5 4.6
9000 6.9 44.4 250 19 10 9.0 4.9 | 6.4 43.5 250 25 13 10.4 5.7
8750 7.5 45.5 250 18 9 7.3 4.0 | 8.0 46.4 250 24 12 9.5 5.2
8500 8.0 46.4 250 17 9 8.1 4.5 | 8.7 47.7 255 23 12 10.2 5.6
8250 8.6 47.5 250 16 8 6.5 3.6 | 9.4 48.9 255 23 12 8.8 4.8
8000 9.0 48.2 255 15 8 6.9 3.8 | 10.1 50.2 255 24 12 9.3 5.1
7750 9.7 49.5 255 14 7 8.8 4.8 | 10.9 51.6 255 23 12 11.1 6.1
7500 10.3 50.5 250 12 6 8.1 4.4 | 11.7 53.1 255 23 12 10.2 5.6
7250 10.8 51.4 255 11 6 5.0 2.8 | 12.4 54.3 255 23 12 8.0 4.4
7000 11.2 52.2 260 10 5 7.1 3.9 | 13.0 55.4 255 23 12 9.6 5.3
6750 11.9 53.4 255 9 5 10.9 6.0 | 13.8 56.8 255 22 11 12.3 6.8
6500 12.6 54.7 250 8 4 9.5 5.2 | 14.7 58.5 255 21 11 10.9 6.0
6250 13.3 55.9 255 8 4 9.4 5.2 | 15.5 59.9 260 21 11 10.9 6.0
6000 14.0 57.2 260 8 4 8.6 4.7 | 16.3 61.3 260 22 11 8.7 4.8
5750 14.7 58.5 255 7 4 12.7 7.0 | 17.0 62.6 260 19 10 15.1 8.3
5500 16.6 61.9 260 6 3 44.9 24.6 | 20.0 68.0 260 17 9 82.0 45.0
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
05/23/2024 at 1500 MDT | 05/23/2024 at 1800 MDT
|
CAPE... +5.8 LI... +0.9 | CAPE... 0.0 LI... +3.8
CINH... -2.5 K Index... +21.7 | CINH... -0.1 K Index... +14.3
|
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 -54.2 -65.6 255 48 25 1.2 0.6 | -54.1 -65.4 260 46 23 1.1 0.6
45000 -52.6 -62.7 260 62 32 -1.8 -1.0 | -52.7 -62.9 265 59 31 -1.6 -0.9
40000 -55.0 -67.0 260 74 38 -1.6 -0.9 | -54.8 -66.6 265 75 39 -1.4 -0.8
38000 -54.7 -66.5 260 77 40 2.0 1.1 | -54.2 -65.6 265 79 41 2.7 1.5
36000 -53.5 -64.3 260 78 40 2.0 1.1 | -52.4 -62.3 265 81 42 2.7 1.5
34000 -51.0 -59.8 260 77 40 7.9 4.3 | -50.1 -58.2 265 80 41 6.8 3.8
32000 -46.2 -51.2 260 74 38 7.9 4.4 | -45.9 -50.6 265 76 39 6.9 3.8
30000 -41.5 -42.7 260 71 37 8.0 4.4 | -41.6 -42.9 265 72 37 8.0 4.4
29000 -39.1 -38.4 260 69 36 8.0 4.4 | -39.2 -38.6 260 71 37 8.0 4.4
28000 -36.7 -34.1 255 68 35 8.0 4.4 | -36.8 -34.2 260 69 36 8.0 4.4
27000 -34.4 -29.9 255 66 34 7.7 4.2 | -34.5 -30.1 260 68 35 7.6 4.2
26000 -32.1 -25.8 255 65 34 7.5 4.1 | -32.2 -26.0 260 67 34 7.5 4.1
25000 -29.9 -21.8 255 65 33 7.5 4.1 | -30.0 -22.0 260 65 34 7.5 4.1
24000 -27.6 -17.7 255 64 33 7.3 4.0 | -27.8 -18.0 255 64 33 7.3 4.0
23000 -25.6 -14.1 255 63 32 6.8 3.8 | -25.8 -14.4 255 63 32 6.7 3.7
22000 -23.6 -10.5 255 62 32 6.9 3.8 | -23.3 -9.9 255 61 31 6.7 3.7
21000 -21.1 -6.0 250 60 31 6.8 3.7 | -21.3 -6.3 255 60 31 7.5 4.1
20000 -19.1 -2.4 250 57 29 6.8 3.7 | -19.0 -2.2 250 58 30 7.5 4.1
19500 -18.1 -0.6 250 56 29 6.8 3.8 | -17.9 -0.2 250 58 30 7.5 4.1
19000 -17.1 1.2 250 55 28 6.8 3.7 | -16.8 1.8 250 57 29 7.5 4.1
18500 -16.0 3.2 245 54 28 7.6 4.2 | -15.7 3.7 250 56 29 7.2 4.0
18000 -14.9 5.2 245 52 27 7.6 4.2 | -14.7 5.5 250 55 28 7.2 4.0
17500 -13.8 7.2 245 50 26 7.4 4.1 | -13.6 7.5 250 53 27 7.1 3.9
17000 -12.8 9.0 245 48 25 7.1 3.9 | -12.6 9.3 250 51 26 7.0 3.9
16500 -11.7 10.9 245 45 23 7.1 3.9 | -11.6 11.1 250 49 25 7.1 3.9
16000 -10.7 12.7 245 42 22 7.3 4.0 | -10.6 12.9 250 47 24 6.2 3.4
15500 -9.6 14.7 245 39 20 7.3 4.0 | -9.7 14.5 250 44 22 6.3 3.5
15000 -8.5 16.7 245 36 19 7.9 4.3 | -8.7 16.3 250 40 21 6.5 3.6
14500 -7.3 18.9 250 35 18 8.1 4.4 | -7.7 18.1 255 37 19 6.6 3.6
14000 -6.1 21.0 250 34 17 8.2 4.5 | -6.7 19.9 255 34 18 7.2 3.9
13500 -4.9 23.2 250 32 17 8.3 4.5 | -5.6 21.9 260 32 16 7.7 4.2
13000 -3.6 25.5 250 31 16 8.3 4.5 | -4.4 24.1 260 29 15 7.8 4.3
12500 -2.4 27.7 255 31 16 8.2 4.5 | -3.2 26.2 265 28 14 8.0 4.4
12000 -1.2 29.8 255 31 16 8.2 4.5 | -2.0 28.4 270 26 14 8.0 4.4
11500 0.0 32.0 260 30 15 8.2 4.5 | -0.8 30.6 275 25 13 8.1 4.5
11000 1.3 34.3 260 29 15 7.9 4.3 | 0.5 32.9 280 24 12 7.9 4.3
10500 2.3 36.1 260 27 14 6.1 3.4 | 1.5 34.7 285 23 12 6.5 3.6
10250 2.9 37.2 260 27 14 9.6 5.3 | 2.1 35.8 285 22 11 8.9 4.9
10000 3.7 38.7 265 26 14 12.1 6.6 | 2.9 37.2 290 21 11 10.9 6.0
9750 4.5 40.1 265 26 13 8.9 4.9 | 3.6 38.5 290 21 11 9.0 4.9
9500 5.1 41.2 265 26 13 8.0 4.4 | 4.2 39.6 290 21 11 8.5 4.6
9250 5.7 42.3 265 26 13 8.7 4.8 | 4.9 40.8 295 21 11 8.6 4.7
9000 6.4 43.5 265 26 13 10.7 5.9 | 5.6 42.1 295 21 11 10.0 5.5
8750 7.3 45.1 270 25 13 10.7 5.9 | 6.3 43.3 295 21 11 10.2 5.6
8500 8.0 46.4 270 25 13 9.6 5.2 | 7.1 44.8 295 20 11 9.4 5.1
8250 8.7 47.7 270 25 13 9.9 5.4 | 8.5 47.3 300 20 10 9.3 5.1
8000 10.2 50.4 270 25 13 9.8 5.4 | 9.2 48.6 300 20 10 9.7 5.3
7750 10.9 51.6 270 24 13 10.5 5.8 | 9.9 49.8 300 20 10 10.3 5.7
7500 11.7 53.1 270 24 12 9.8 5.4 | 10.7 51.3 300 20 10 9.6 5.2
7250 12.4 54.3 270 24 12 8.3 4.6 | 11.3 52.3 300 20 10 8.2 4.5
7000 13.0 55.4 270 24 13 9.9 5.4 | 12.0 53.6 305 20 10 9.5 5.2
6750 13.9 57.0 270 23 12 11.7 6.4 | 12.8 55.0 305 19 10 10.8 5.9
6500 14.7 58.5 270 22 11 11.0 6.0 | 13.5 56.3 300 18 9 10.5 5.8
6250 15.5 59.9 270 22 11 11.8 6.5 | 14.4 57.9 305 18 10 11.6 6.3
6000 16.4 61.5 270 22 11 8.8 4.8 | 15.2 59.4 305 19 10 8.5 4.7
5750 17.0 62.6 270 20 10 13.6 7.5 | 15.7 60.3 305 17 9 8.9 4.9
5500 20.0 68.0 275 18 9 82.9 45.5 | 17.6 63.7 305 15 8 54.4 29.8
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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