Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
895
UXUS97 KGJT 231306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
606 AM MST Saturday, November 23, 2024
This forecast is for Saturday, November 23, 2024:
If the trigger temperature of 66.3 F/19.1 C is reached...then
Thermal Soaring Index....................... Fair
Maximum rate of lift........................ 207 ft/min (1.0 m/s)
Maximum height of thermals.................. 6947 ft MSL (2108 ft AGL)
Forecast maximum temperature................... 56.0 F/13.8 C
Time of trigger temperature.................... None
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................. 6704 ft MSL (1865 ft AGL)
Thermal soaring outlook for Sunday 11/24....... Fair
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:06:58 / 16:54:31 MST
Total possible sunshine........... 9 hr 47 min 33 sec (587 min 33 sec)
Altitude of sun at 12:00:44 MST... 30.32 degrees
Upper air data from rawinsonde observation taken on 11/23/2024 at 0500 MST
Freezing level.................. 4994 ft MSL (155 ft AGL)
Additional freezing level....... 12924 ft MSL (8085 ft AGL)
Convective condensation level... 26541 ft MSL (21702 ft AGL)
Lifted condensation level....... 17689 ft MSL (12850 ft AGL)
Lifted index.................... +16.3
K index......................... -49.5
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 -67.0 -88.6 265 66 34 -8.7 -4.8 88.8 191.8 43.0 M M
45000 -67.4 -89.3 290 79 41 4.3 2.3 63.0 145.4 30.4 M M
40000 -63.6 -82.5 280 69 36 3.1 1.7 45.9 114.6 21.4 M M
38000 -58.7 -73.7 285 65 34 8.5 4.6 44.4 111.9 21.0 M M
36000 -53.1 -63.6 280 66 34 8.8 4.8 43.0 109.3 20.6 M M
34000 -47.7 -53.9 275 66 34 8.8 4.8 42.3 108.2 20.7 M M
32000 -42.4 -44.3 280 61 31 8.9 4.9 41.6 106.8 20.7 M M
30000 -37.5 -35.5 275 50 26 8.5 4.6 40.3 104.6 20.3 M M
29000 -34.8 -30.6 275 50 26 8.8 4.8 39.9 103.8 20.2 M M
28000 -32.3 -26.1 265 46 24 7.9 4.4 39.4 103.0 20.1 M M
27000 -29.9 -21.8 255 42 22 8.4 4.6 38.8 101.8 19.8 M M
26000 -27.3 -17.1 250 47 24 8.5 4.6 38.3 100.9 19.7 M M
25000 -25.1 -13.2 255 48 25 5.1 2.8 37.5 99.4 19.2 M M
24000 -23.3 -9.9 260 51 26 7.4 4.1 36.0 96.9 18.3 M M
23000 -21.0 -5.8 260 49 25 7.7 4.2 35.2 95.4 17.8 M M
22000 -19.0 -2.2 265 49 25 6.9 3.8 34.2 93.5 17.1 M M
21000 -16.9 1.6 260 50 26 6.9 3.8 33.2 91.8 16.5 M M
20000 -14.5 5.9 255 47 24 6.8 3.7 32.5 90.5 16.1 M M
19500 -13.4 7.9 255 45 23 7.3 4.0 32.1 89.8 15.9 M M
19000 -11.7 10.9 255 43 22 8.6 4.7 31.5 88.6 15.5 M M
18500 -10.4 13.3 250 41 21 8.1 4.5 31.3 88.4 15.5 M M
18000 -9.1 15.6 250 43 22 7.8 4.3 31.0 87.8 15.3 M M
17500 -8.0 17.6 245 41 21 8.3 4.5 30.7 87.3 15.1 M M
17000 -7.6 18.3 240 40 21 0.6 0.3 29.4 85.0 14.1 M M
16500 -6.9 19.6 240 41 21 5.6 3.1 28.6 83.5 13.4 M M
16000 -6.0 21.2 240 39 20 6.2 3.4 28.0 82.4 13.0 M M
15500 -5.0 23.0 240 37 19 6.4 3.5 27.5 81.4 12.5 M M
15000 -4.0 24.8 240 36 19 6.4 3.5 26.9 80.4 12.1 M M
14500 -3.0 26.6 235 37 19 6.5 3.5 26.4 79.5 11.7 M M
14000 -2.1 28.2 240 35 18 6.5 3.6 25.8 78.5 11.3 M M
13500 -1.1 30.0 235 32 17 6.5 3.6 25.3 77.5 10.9 M M
13000 -0.1 31.8 235 29 15 6.5 3.6 24.7 76.5 10.4 M M
12500 0.9 33.6 235 32 16 6.8 3.8 24.2 75.5 10.0 M M
12000 1.6 34.9 225 34 18 2.9 1.6 23.4 74.1 9.3 M M
11500 2.2 36.0 230 35 18 4.3 2.4 22.4 72.4 8.5 M M
11000 2.8 37.0 235 34 17 3.9 2.2 21.6 70.8 7.7 M M
10500 3.7 38.7 230 30 15 8.2 4.5 21.0 69.7 7.1 M M
10250 4.3 39.7 225 28 14 7.8 4.3 20.8 69.5 7.0 M M
10000 4.9 40.8 220 26 13 7.9 4.3 20.7 69.2 6.9 M M
9750 5.5 41.9 220 26 13 6.0 3.3 20.5 68.8 6.7 M M
9500 5.8 42.4 220 26 13 5.3 2.9 20.1 68.2 6.4 M M
9250 6.3 43.3 225 24 13 6.9 3.8 19.8 67.7 6.2 M M
9000 6.8 44.2 210 23 12 4.9 2.7 19.6 67.2 5.9 M M
8750 6.9 44.4 210 22 11 -0.6 -0.3 19.0 66.2 5.4 M M
8500 6.8 44.2 215 18 9 0.8 0.4 18.1 64.6 4.5 M M
8250 7.1 44.8 210 17 9 5.5 3.0 17.7 63.8 4.1 M M
8000 7.5 45.5 195 18 10 5.8 3.2 17.3 63.2 3.8 M M
7750 7.9 46.2 185 18 9 5.3 2.9 17.0 62.6 3.5 M M
7500 8.4 47.1 175 19 10 7.2 3.9 16.7 62.1 3.2 M M
7250 8.8 47.8 165 20 10 0.2 0.1 16.4 61.5 2.9 M M
7000 8.0 46.4 155 22 11 -21.2 -11.6 14.9 58.8 1.3 M M
6750 5.7 42.3 155 20 10 -35.5 -19.5 11.8 53.3 -1.7 241 1.2
6500 3.4 38.1 145 15 8 -15.8 -8.7 8.8 47.8 -4.7 302 1.5
6250 3.2 37.8 130 10 5 4.1 2.3 7.9 46.2 -5.6 300 1.5
6000 3.5 38.3 130 8 4 5.6 3.1 7.5 45.4 -6.1 284 1.4
5750 3.8 38.8 135 7 4 -2.9 -1.6 7.0 44.6 -6.6 269 1.4
5500 3.0 37.4 150 7 4 -13.7 -7.5 5.5 41.9 -8.1 286 1.5
5250 2.0 35.6 130 10 5 -10.0 -5.5 3.8 38.9 -9.8 306 1.6
5000 1.1 34.0 120 14 7 -18.6 -10.2 2.2 35.9 -11.5 326 1.7
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
11/23/2024 at 0800 MST | 11/23/2024 at 1100 MST
|
CAPE... 0.0 LI... +7.2 | CAPE... 0.0 LI... +7.4
CINH... -0.1 K Index... -23.6 | CINH... -0.1 K Index... -20.0
|
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 -68.5 -91.3 275 64 33 1.6 0.9 | -68.2 -90.8 275 61 31 2.0 1.1
45000 -65.9 -86.6 280 78 40 2.6 1.4 | -65.0 -85.0 275 76 39 2.4 1.3
40000 -62.0 -79.6 275 81 42 2.7 1.5 | -61.5 -78.7 270 85 44 2.5 1.4
38000 -58.0 -72.4 275 80 41 8.0 4.4 | -57.7 -71.9 270 84 43 7.9 4.3
36000 -53.3 -63.9 275 78 40 8.0 4.4 | -53.0 -63.4 270 81 42 7.9 4.3
34000 -47.7 -53.9 275 75 39 8.6 4.7 | -47.5 -53.5 270 78 40 8.5 4.6
32000 -42.5 -44.5 275 71 37 8.6 4.7 | -42.4 -44.3 265 75 39 8.5 4.6
30000 -37.6 -35.7 270 66 34 8.1 4.4 | -37.4 -35.3 265 71 37 8.2 4.5
29000 -35.2 -31.4 270 62 32 8.1 4.4 | -35.0 -31.0 265 69 36 8.2 4.5
28000 -32.8 -27.0 265 58 30 8.1 4.4 | -32.5 -26.5 260 67 35 8.2 4.5
27000 -30.5 -22.9 265 56 29 7.1 3.9 | -30.2 -22.4 260 65 34 7.4 4.1
26000 -28.3 -18.9 260 54 28 7.2 3.9 | -28.0 -18.4 255 63 33 7.5 4.1
25000 -26.2 -15.2 255 52 27 7.2 3.9 | -25.7 -14.3 250 62 32 7.5 4.1
24000 -24.0 -11.2 255 52 27 7.2 4.0 | -23.6 -10.5 250 60 31 6.7 3.7
23000 -21.9 -7.4 250 52 27 7.2 4.0 | -21.6 -6.9 250 60 31 6.7 3.7
22000 -19.7 -3.5 250 52 27 7.2 4.0 | -19.6 -3.3 250 60 31 6.7 3.6
21000 -16.9 1.6 250 52 27 7.6 4.2 | -17.0 1.4 245 60 31 7.2 4.0
20000 -14.7 5.5 250 50 26 7.7 4.2 | -14.8 5.4 245 58 30 7.2 4.0
19500 -13.5 7.7 250 50 26 7.6 4.2 | -13.7 7.3 245 57 29 7.2 4.0
19000 -12.4 9.7 250 49 25 7.5 4.1 | -12.6 9.3 245 56 29 7.2 4.0
18500 -11.3 11.7 250 48 25 7.0 3.8 | -11.6 11.1 245 55 28 6.8 3.7
18000 -10.2 13.6 250 46 24 7.0 3.9 | -10.6 12.9 245 54 28 6.8 3.7
17500 -9.2 15.4 250 45 23 6.9 3.8 | -9.6 14.7 245 53 27 6.6 3.6
17000 -8.2 17.2 250 44 23 6.9 3.8 | -8.6 16.5 245 52 27 6.6 3.6
16500 -7.1 19.2 245 44 22 7.0 3.8 | -7.6 18.3 245 51 26 6.6 3.6
16000 -6.1 21.0 245 43 22 7.0 3.9 | -6.6 20.1 245 50 26 6.8 3.7
15500 -5.0 23.0 245 42 22 7.0 3.9 | -5.6 21.9 245 49 25 6.8 3.7
15000 -4.0 24.8 245 41 21 7.0 3.8 | -4.6 23.7 245 48 25 6.9 3.8
14500 -2.9 26.8 245 40 21 7.0 3.9 | -3.5 25.7 245 47 24 6.9 3.8
14000 -1.9 28.6 245 40 20 6.2 3.4 | -2.5 27.5 245 46 24 6.5 3.6
13500 -1.0 30.2 245 39 20 6.1 3.4 | -1.5 29.3 245 45 23 6.4 3.5
13000 -0.0 32.0 245 38 20 5.6 3.1 | -0.6 30.9 245 44 23 5.9 3.2
12500 0.8 33.4 240 37 19 5.3 2.9 | 0.3 32.5 240 43 22 5.5 3.0
12000 1.6 34.9 240 36 19 4.9 2.7 | 1.1 34.0 240 42 22 5.1 2.8
11500 2.2 36.0 235 35 18 4.5 2.5 | 1.8 35.2 235 40 21 4.6 2.5
11000 2.9 37.2 235 34 17 3.8 2.1 | 2.5 36.5 235 38 20 3.9 2.1
10500 3.4 38.1 230 31 16 2.5 1.4 | 2.9 37.2 230 36 18 2.4 1.3
10250 3.6 38.5 230 30 16 5.5 3.0 | 3.2 37.8 230 34 18 4.7 2.6
10000 4.1 39.4 230 29 15 5.7 3.1 | 3.6 38.5 230 32 17 5.9 3.2
9750 4.4 39.9 225 27 14 2.6 1.4 | 3.9 39.0 225 30 15 3.9 2.1
9500 4.6 40.3 225 26 13 3.5 1.9 | 4.2 39.6 220 28 14 3.9 2.1
9250 4.8 40.6 220 24 12 3.0 1.7 | 4.5 40.1 220 26 14 3.7 2.0
9000 5.0 41.0 215 22 12 1.2 0.7 | 4.7 40.5 215 25 13 2.6 1.5
8750 5.0 41.0 215 21 11 1.0 0.6 | 4.9 40.8 215 23 12 3.1 1.7
8500 5.2 41.4 210 20 10 2.0 1.1 | 5.2 41.4 210 21 11 4.1 2.2
8250 5.3 41.5 205 19 10 2.0 1.1 | 5.5 41.9 205 20 10 3.6 2.0
8000 5.6 42.1 195 16 8 1.5 0.8 | 5.7 42.3 200 19 10 3.1 1.7
7750 5.7 42.3 195 15 8 0.4 0.2 | 6.2 43.2 195 16 8 4.1 2.2
7500 5.7 42.3 190 14 7 1.5 0.8 | 6.5 43.7 195 15 8 2.9 1.6
7250 5.9 42.6 180 14 7 2.8 1.5 | 6.7 44.1 190 14 7 1.4 0.7
7000 6.0 42.8 175 14 7 0.9 0.5 | 6.8 44.2 185 13 7 3.2 1.7
6750 6.0 42.8 175 11 6 -1.5 -0.8 | 7.1 44.8 185 10 5 4.7 2.6
6500 5.8 42.4 170 10 5 -2.3 -1.3 | 7.4 45.3 180 8 4 4.8 2.6
6250 5.6 42.1 165 8 4 -4.3 -2.4 | 7.8 46.0 180 7 4 4.5 2.5
6000 5.3 41.5 160 8 4 0.2 0.1 | 8.2 46.8 175 6 3 6.5 3.5
5750 5.2 41.4 145 4 2 -11.2 -6.2 | 8.8 47.8 185 5 3 12.6 6.9
5500 0.8 33.4 085 2 1 -99.0 -54.3 | 9.8 49.6 185 3 2 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
11/23/2024 at 1400 MST | 11/23/2024 at 1700 MST
|
CAPE... 0.0 LI... +8.3 | CAPE... 0.0 LI... +8.6
CINH... 0.0 K Index... -14.9 | CINH... -0.0 K Index... -4.6
|
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 -67.4 -89.3 270 61 31 1.6 0.9 | -67.4 -89.3 265 58 30 2.0 1.1
45000 -64.8 -84.6 270 82 42 2.5 1.4 | -64.1 -83.4 265 83 43 2.6 1.4
40000 -61.1 -78.0 265 82 42 2.6 1.4 | -60.3 -76.5 260 81 42 2.7 1.5
38000 -57.4 -71.3 260 81 42 7.7 4.2 | -56.9 -70.4 255 78 40 6.7 3.7
36000 -52.8 -63.0 260 80 41 7.7 4.2 | -52.9 -63.2 245 76 39 6.7 3.7
34000 -47.4 -53.3 260 79 41 8.5 4.6 | -48.4 -55.1 245 76 39 8.8 4.8
32000 -42.3 -44.1 260 79 40 8.5 4.6 | -43.1 -45.6 245 77 39 8.8 4.8
30000 -37.4 -35.3 255 78 40 8.1 4.5 | -38.0 -36.4 250 77 39 8.1 4.4
29000 -34.9 -30.8 255 77 40 8.1 4.5 | -35.6 -32.1 250 76 39 8.1 4.4
28000 -32.5 -26.5 255 76 39 8.2 4.5 | -33.2 -27.8 250 76 39 8.1 4.4
27000 -30.1 -22.2 255 75 39 7.5 4.1 | -30.2 -22.4 250 75 39 7.4 4.1
26000 -27.8 -18.0 255 74 38 7.6 4.2 | -28.0 -18.4 250 75 38 7.5 4.1
25000 -25.6 -14.1 250 73 37 7.6 4.2 | -25.7 -14.3 250 74 38 7.5 4.1
24000 -23.3 -9.9 250 71 37 7.6 4.2 | -23.5 -10.3 250 73 38 7.5 4.1
23000 -21.1 -6.0 250 70 36 7.6 4.1 | -21.3 -6.3 250 72 37 7.5 4.1
22000 -18.8 -1.8 250 68 35 7.6 4.2 | -19.0 -2.2 250 71 36 7.5 4.1
21000 -16.2 2.8 250 66 34 6.1 3.4 | -16.9 1.6 250 69 36 6.6 3.6
20000 -14.4 6.1 250 64 33 6.1 3.4 | -14.9 5.2 250 67 34 6.7 3.7
19500 -13.5 7.7 250 63 32 6.1 3.4 | -13.9 7.0 250 65 34 6.8 3.7
19000 -12.6 9.3 250 62 32 6.2 3.4 | -12.9 8.8 250 64 33 6.8 3.7
18500 -11.7 10.9 250 61 31 5.8 3.2 | -11.9 10.6 250 63 32 5.9 3.2
18000 -10.8 12.6 250 59 31 5.9 3.2 | -11.1 12.0 250 61 32 5.8 3.2
17500 -9.9 14.2 250 58 30 5.9 3.3 | -10.3 13.5 250 60 31 5.8 3.2
17000 -9.0 15.8 250 56 29 6.0 3.3 | -9.4 15.1 250 58 30 6.0 3.3
16500 -8.1 17.4 250 55 28 6.0 3.3 | -8.5 16.7 250 56 29 6.0 3.3
16000 -7.2 19.0 250 53 27 6.1 3.4 | -7.7 18.1 250 53 27 5.3 2.9
15500 -6.2 20.8 250 52 27 6.1 3.4 | -6.9 19.6 250 51 26 5.3 2.9
15000 -5.3 22.5 250 50 26 6.1 3.3 | -6.1 21.0 250 48 25 5.5 3.0
14500 -4.4 24.1 250 48 25 6.0 3.3 | -5.2 22.6 250 46 23 5.6 3.1
14000 -3.5 25.7 245 47 24 6.0 3.3 | -4.3 24.3 250 43 22 5.7 3.1
13500 -2.6 27.3 245 45 23 5.9 3.2 | -3.4 25.9 245 41 21 5.8 3.2
13000 -1.7 28.9 245 43 22 5.7 3.2 | -2.5 27.5 245 39 20 5.8 3.2
12500 -0.9 30.4 240 42 22 5.5 3.0 | -1.7 28.9 240 39 20 5.6 3.1
12000 -0.1 31.8 240 40 21 5.4 3.0 | -0.8 30.6 240 38 20 5.6 3.1
11500 0.7 33.3 235 38 20 5.2 2.8 | 0.0 32.0 235 37 19 5.7 3.1
11000 1.5 34.7 235 36 19 4.9 2.7 | 0.9 33.6 235 36 19 5.6 3.1
10500 2.1 35.8 230 34 17 3.5 1.9 | 1.7 35.1 230 34 18 5.2 2.8
10250 2.4 36.3 230 32 17 5.3 2.9 | 2.1 35.8 230 33 17 6.0 3.3
10000 2.9 37.2 225 31 16 7.7 4.2 | 2.6 36.7 225 32 16 8.2 4.5
9750 3.4 38.1 225 29 15 6.2 3.4 | 3.3 37.9 220 30 16 7.4 4.0
9500 3.8 38.8 220 27 14 5.3 2.9 | 3.7 38.7 220 28 15 6.1 3.4
9250 4.2 39.6 220 25 13 5.0 2.8 | 4.7 40.5 215 24 13 7.7 4.2
9000 4.6 40.3 215 23 12 6.8 3.8 | 5.3 41.5 210 23 12 7.7 4.2
8750 5.2 41.4 210 22 11 7.3 4.0 | 5.8 42.4 210 22 11 6.0 3.3
8500 5.6 42.1 210 20 11 5.7 3.1 | 6.2 43.2 205 20 10 6.5 3.6
8250 6.5 43.7 200 17 9 5.0 2.7 | 6.7 44.1 200 19 10 6.4 3.5
8000 6.9 44.4 200 15 8 5.5 3.0 | 7.2 45.0 200 18 9 6.1 3.4
7750 7.3 45.1 200 13 7 6.8 3.8 | 7.6 45.7 200 16 8 5.9 3.2
7500 7.8 46.0 195 12 6 6.0 3.3 | 8.1 46.6 195 15 8 5.9 3.3
7250 8.2 46.8 195 10 5 4.7 2.6 | 8.5 47.3 195 13 7 5.8 3.2
7000 8.6 47.5 200 8 4 6.3 3.5 | 8.9 48.0 195 12 6 4.9 2.7
6750 9.2 48.6 200 7 4 8.0 4.4 | 9.2 48.6 195 10 5 4.2 2.3
6500 9.7 49.5 205 6 3 8.0 4.4 | 9.5 49.1 195 8 4 4.5 2.5
6250 10.4 50.7 215 5 3 8.7 4.8 | 9.9 49.8 200 6 3 4.2 2.3
6000 11.0 51.8 225 4 2 8.0 4.4 | 10.2 50.4 205 5 2 5.3 2.9
5750 11.7 53.1 220 4 2 10.8 5.9 | 10.3 50.5 210 3 2 -6.8 -3.7
5500 13.0 55.4 235 3 2 31.4 17.2 | 7.5 45.5 270 2 1 -85.0 -46.6
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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