Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
372
UXUS97 KGJT 011306
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
706 AM MDT Tuesday, October 1, 2024
This forecast is for Tuesday, October 1, 2024:
If the trigger temperature of 80.8 F/27.1 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 663 ft/min (3.4 m/s)
Maximum height of thermals.................. 13141 ft MSL (8302 ft AGL)
Forecast maximum temperature................... 88.0 F/31.6 C
Time of trigger temperature.................... 1245 MDT
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................. 9811 ft MSL (4972 ft AGL)
Thermal soaring outlook for Wednesday 10/02.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 07:10:59 / 18:56:07 MDT
Total possible sunshine........... 11 hr 45 min 8 sec (705 min 8 sec)
Altitude of sun at 13:03:33 MDT... 47.27 degrees
Upper air data from rawinsonde observation taken on 10/01/2024 at 0600 MDT
Freezing level.................. 16018 ft MSL (11179 ft AGL)
Convective condensation level... 22411 ft MSL (17572 ft AGL)
Lifted condensation level....... 19818 ft MSL (14979 ft AGL)
Lifted index.................... +4.3
K index......................... -9.1
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 -63.4 -82.1 300 29 15 -0.4 -0.2 90.7 195.3 34.4 M M
45000 -66.1 -87.0 290 26 13 6.6 3.6 60.5 140.9 18.2 M M
40000 -57.0 -70.6 320 28 14 8.5 4.7 51.9 125.4 13.8 M M
38000 -51.9 -61.4 315 23 12 8.4 4.6 50.8 123.4 13.4 M M
36000 -47.1 -52.8 325 27 14 8.7 4.8 49.3 120.8 12.8 M M
34000 -42.2 -44.0 320 27 14 8.8 4.8 47.9 118.3 12.1 M M
32000 -37.3 -35.1 325 30 16 9.4 5.2 46.7 116.1 11.5 M M
30000 -31.4 -24.5 320 25 13 7.9 4.4 45.8 114.4 11.1 M M
29000 -29.2 -20.6 320 26 13 7.5 4.1 44.9 112.8 10.5 M M
28000 -27.0 -16.6 330 22 11 7.6 4.1 44.0 111.2 10.0 M M
27000 -24.7 -12.5 325 19 10 7.9 4.3 43.2 109.8 9.4 M M
26000 -22.3 -8.1 330 23 12 7.8 4.3 42.5 108.5 9.0 M M
25000 -20.3 -4.5 320 20 10 5.8 3.2 41.4 106.6 8.2 M M
24000 -18.3 -0.9 310 17 9 7.9 4.4 40.3 104.5 7.3 M M
23000 -16.0 3.2 310 15 8 6.8 3.7 39.6 103.2 6.8 M M
22000 -13.7 7.3 320 13 7 8.1 4.5 38.8 101.8 6.2 M M
21000 -11.3 11.7 320 13 7 8.2 4.5 38.2 100.8 5.8 M M
20000 -8.8 16.2 320 15 8 8.1 4.5 37.6 99.7 5.4 M M
19500 -7.6 18.3 320 17 9 8.0 4.4 37.3 99.2 5.2 M M
19000 -6.5 20.3 310 21 11 7.1 3.9 36.9 98.5 4.9 M M
18500 -5.4 22.3 300 20 10 7.1 3.9 36.5 97.7 4.5 M M
18000 -4.4 24.1 310 21 11 7.1 3.9 36.0 96.8 4.1 M M
17500 -3.3 26.1 315 22 11 7.1 3.9 35.6 96.0 3.7 M M
17000 -2.3 27.9 305 20 10 6.9 3.8 35.1 95.2 3.3 M M
16500 -0.8 30.6 305 17 9 6.5 3.6 34.3 93.8 2.7 M M
16000 0.3 32.5 295 16 8 6.6 3.6 33.8 92.8 2.3 M M
15500 1.3 34.3 285 18 9 6.7 3.7 33.2 91.8 1.8 M M
15000 2.3 36.1 280 20 10 7.4 4.1 32.8 91.0 1.4 M M
14500 3.4 38.1 280 21 11 7.5 4.1 32.4 90.4 1.0 M M
14000 4.4 39.9 265 21 11 7.7 4.2 32.1 89.7 0.6 M M
13500 5.5 41.9 255 18 9 7.6 4.2 31.7 89.1 0.2 M M
13000 6.5 43.7 240 16 8 7.6 4.2 31.4 88.5 -0.2 645 3.3
12500 7.6 45.7 230 17 9 7.2 4.0 31.0 87.8 -0.5 598 3.0
12000 8.7 47.7 220 13 7 7.2 4.0 30.6 87.1 -0.9 550 2.8
11500 9.8 49.6 230 10 5 7.3 4.0 30.2 86.3 -1.2 502 2.5
11000 10.9 51.6 250 8 4 7.3 4.0 29.8 85.6 -1.6 454 2.3
10500 11.9 53.4 245 8 4 5.1 2.8 29.2 84.6 -2.1 411 2.1
10250 12.2 54.0 245 6 3 5.5 3.0 28.9 84.0 -2.5 393 2.0
10000 12.6 54.7 240 4 2 6.6 3.6 28.6 83.5 -2.8 373 1.9
9750 13.2 55.8 250 3 2 7.0 3.9 28.4 83.1 -3.1 350 1.8
9500 13.7 56.7 265 3 2 6.9 3.8 28.2 82.7 -3.3 327 1.7
9250 14.2 57.6 290 3 1 7.0 3.8 28.0 82.3 -3.5 305 1.5
9000 14.7 58.5 350 3 1 7.0 3.8 27.7 81.9 -3.7 282 1.4
8750 15.2 59.4 350 3 1 7.0 3.8 27.5 81.5 -3.9 259 1.3
8500 15.8 60.4 345 2 1 7.0 3.8 27.3 81.1 -4.1 236 1.2
8250 16.3 61.3 325 1 1 7.0 3.8 27.1 80.8 -4.4 213 1.1
8000 16.8 62.2 345 3 1 6.9 3.8 26.9 80.4 -4.6 190 1.0
7750 17.3 63.1 335 3 2 7.0 3.8 26.7 80.0 -4.8 167 0.8
7500 17.8 64.0 330 3 2 6.9 3.8 26.4 79.6 -5.0 144 0.7
7250 18.3 64.9 330 2 1 6.0 3.3 26.2 79.1 -5.3 122 0.6
7000 18.7 65.7 345 1 1 5.3 2.9 25.9 78.5 -5.6 103 0.5
6750 19.1 66.4 010 1 1 5.7 3.1 25.5 78.0 -6.0 84 0.4
6500 19.5 67.1 055 2 1 4.9 2.7 25.2 77.4 -6.3 64 0.3
6250 19.7 67.5 055 5 3 0.8 0.4 24.7 76.5 -6.8 50 0.3
6000 19.7 67.5 070 7 4 1.7 0.9 24.0 75.2 -7.6 42 0.2
5750 20.1 68.2 075 8 4 7.5 4.1 23.6 74.5 -8.0 25 0.1
5500 20.4 68.7 085 9 4 -2.1 -1.2 23.2 73.8 -8.4 7 0.0
5250 19.4 66.9 110 9 4 -24.2 -13.3 21.5 70.7 -10.2 30 0.2
5000 17.0 62.6 130 9 5 -35.0 -19.2 18.4 65.2 -13.3 94 0.5
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
10/01/2024 at 0900 MDT | 10/01/2024 at 1200 MDT
|
CAPE... 0.0 LI... +6.2 | CAPE... 0.0 LI... +6.1
CINH... -1.6 K Index... -2.5 | CINH... 0.0 K Index... -2.0
|
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 -65.3 -85.5 330 24 12 0.2 0.1 | -65.1 -85.2 360 18 9 0.0 0.0
45000 -63.5 -82.3 340 25 13 4.1 2.3 | -63.4 -82.1 020 26 14 4.2 2.3
40000 -56.4 -69.5 345 28 14 7.2 3.9 | -56.3 -69.3 030 33 17 7.2 4.0
38000 -52.0 -61.6 345 28 14 7.2 4.0 | -51.9 -61.4 025 29 15 7.3 4.0
36000 -47.7 -53.9 350 28 14 7.3 4.0 | -47.6 -53.7 015 26 13 7.4 4.0
34000 -42.6 -44.7 355 26 14 8.6 4.7 | -42.5 -44.5 010 24 12 8.5 4.7
32000 -37.5 -35.5 360 26 13 8.5 4.7 | -37.4 -35.3 005 22 12 8.5 4.7
30000 -32.3 -26.1 355 24 12 8.6 4.7 | -32.2 -26.0 005 21 11 8.7 4.7
29000 -29.7 -21.5 350 22 12 8.6 4.7 | -29.6 -21.3 005 19 10 8.7 4.8
28000 -27.2 -17.0 350 21 11 7.8 4.3 | -27.0 -16.6 005 18 9 7.8 4.3
27000 -25.0 -13.0 345 20 11 7.5 4.1 | -24.8 -12.6 360 17 9 7.5 4.1
26000 -22.7 -8.9 340 20 10 7.5 4.1 | -21.9 -7.4 350 16 8 7.5 4.1
25000 -19.9 -3.8 335 19 10 7.2 4.0 | -19.7 -3.5 340 15 8 7.0 3.8
24000 -17.8 -0.0 330 18 9 7.2 3.9 | -17.7 0.1 335 14 7 6.8 3.7
23000 -15.7 3.7 325 17 9 7.2 4.0 | -15.7 3.7 325 14 7 6.9 3.8
22000 -13.5 7.7 325 17 9 7.9 4.3 | -13.6 7.5 315 14 7 7.8 4.3
21000 -11.1 12.0 320 16 8 7.9 4.4 | -11.3 11.7 315 14 7 7.9 4.3
20000 -8.8 16.2 320 16 8 7.9 4.4 | -9.0 15.8 310 13 7 7.9 4.3
19500 -7.6 18.3 315 16 8 7.8 4.3 | -7.8 18.0 310 13 7 7.9 4.3
19000 -6.4 20.5 315 16 8 7.7 4.2 | -6.6 20.1 305 13 7 7.8 4.3
18500 -5.3 22.5 315 15 8 7.8 4.3 | -5.4 22.3 305 12 6 7.9 4.3
18000 -4.2 24.4 315 15 8 6.5 3.6 | -4.3 24.3 305 12 6 6.9 3.8
17500 -3.2 26.2 310 15 8 6.5 3.6 | -3.3 26.1 300 12 6 6.9 3.8
17000 -2.2 28.0 305 15 8 6.4 3.5 | -2.2 28.0 295 11 6 6.7 3.7
16500 -1.3 29.7 300 15 8 6.3 3.4 | -1.3 29.7 290 12 6 6.3 3.5
16000 -0.3 31.5 295 15 7 6.3 3.4 | -0.3 31.5 285 12 6 6.3 3.5
15500 0.6 33.1 290 14 7 6.6 3.6 | 0.7 33.3 280 12 6 6.5 3.6
15000 1.6 34.9 280 14 7 6.5 3.6 | 1.6 34.9 275 13 7 6.4 3.5
14500 2.6 36.7 275 14 7 6.8 3.8 | 2.6 36.7 275 13 7 6.9 3.8
14000 3.6 38.5 270 14 7 6.9 3.8 | 3.7 38.7 270 13 7 6.9 3.8
13500 4.7 40.5 265 14 7 7.3 4.0 | 4.7 40.5 265 14 7 7.2 3.9
13000 5.8 42.4 260 14 7 7.6 4.2 | 5.8 42.4 260 14 7 7.3 4.0
12500 6.9 44.4 255 14 7 7.5 4.1 | 6.9 44.4 260 14 7 7.4 4.1
12000 7.9 46.2 250 14 7 7.4 4.1 | 8.0 46.4 255 13 7 7.5 4.1
11500 9.0 48.2 250 13 7 7.3 4.0 | 9.1 48.4 255 13 7 7.5 4.1
11000 10.1 50.2 250 12 6 7.1 3.9 | 10.2 50.4 255 12 6 7.3 4.0
10500 11.1 52.0 250 11 6 6.0 3.3 | 11.3 52.3 255 12 6 6.6 3.6
10250 11.5 52.7 245 10 5 5.3 2.9 | 11.7 53.1 255 12 6 6.4 3.5
10000 12.0 53.6 245 9 5 6.9 3.8 | 12.2 54.0 255 11 6 7.5 4.1
9750 12.5 54.5 245 8 4 7.2 4.0 | 12.8 55.0 255 10 5 7.6 4.2
9500 13.0 55.4 240 7 4 6.6 3.6 | 13.3 55.9 255 9 5 7.0 3.8
9250 13.5 56.3 235 7 3 6.0 3.3 | 13.8 56.8 255 8 4 6.3 3.4
9000 13.9 57.0 230 6 3 6.0 3.3 | 14.3 57.7 255 8 4 7.0 3.8
8750 14.8 58.6 215 5 3 5.1 2.8 | 15.3 59.5 260 5 3 6.5 3.6
8500 15.2 59.4 205 5 2 4.2 2.3 | 15.8 60.4 255 5 2 5.2 2.9
8250 15.5 59.9 195 5 2 4.3 2.4 | 16.2 61.2 255 4 2 7.2 3.9
8000 15.8 60.4 185 4 2 4.0 2.2 | 16.8 62.2 255 3 2 9.1 5.0
7750 16.1 61.0 170 4 2 3.6 2.0 | 17.5 63.5 255 3 1 7.3 4.0
7500 16.3 61.3 165 4 2 3.4 1.9 | 17.9 64.2 255 2 1 5.5 3.0
7250 16.6 61.9 155 5 2 3.7 2.0 | 18.4 65.1 260 2 1 8.1 4.4
7000 16.8 62.2 145 4 2 3.8 2.1 | 19.1 66.4 255 2 1 11.8 6.5
6750 17.1 62.8 135 4 2 3.1 1.7 | 20.0 68.0 255 1 1 10.5 5.8
6500 17.3 63.1 125 3 2 3.8 2.1 | 20.7 69.3 255 1 1 9.8 5.3
6250 17.5 63.5 115 4 2 0.6 0.3 | 21.4 70.5 260 1 1 8.3 4.6
6000 17.4 63.3 110 4 2 -0.6 -0.3 | 22.1 71.8 270 2 1 13.1 7.2
5750 17.7 63.9 095 4 2 7.4 4.1 | 23.6 74.5 270 1 1 26.4 14.5
5500 17.9 64.2 080 3 2 -9.7 -5.3 | 25.1 77.2 275 1 1 1.1 0.6
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
10/01/2024 at 1500 MDT | 10/01/2024 at 1800 MDT
|
CAPE... 0.0 LI... +5.5 | CAPE... 0.0 LI... +4.7
CINH... -0.1 K Index... -1.4 | CINH... -1.7 K Index... -3.0
|
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 -66.2 -87.2 035 15 8 0.5 0.3 | -66.7 -88.1 035 10 5 0.3 0.2
45000 -63.6 -82.5 050 27 14 4.9 2.7 | -64.0 -83.2 060 23 12 5.6 3.1
40000 -55.5 -67.9 040 28 15 7.1 3.9 | -54.8 -66.6 050 31 16 7.2 4.0
38000 -51.2 -60.2 035 23 12 7.2 3.9 | -50.5 -58.9 045 25 13 7.2 4.0
36000 -46.9 -52.4 025 18 9 7.3 4.0 | -46.1 -51.0 035 20 10 7.4 4.1
34000 -42.0 -43.6 025 17 9 8.3 4.5 | -41.2 -42.2 040 17 9 8.2 4.5
32000 -37.0 -34.6 025 17 9 8.2 4.5 | -36.3 -33.3 050 14 7 8.2 4.5
30000 -31.9 -25.4 015 16 8 8.5 4.7 | -31.5 -24.7 035 13 6 7.9 4.4
29000 -29.4 -20.9 010 15 8 8.5 4.7 | -29.2 -20.6 025 12 6 7.9 4.4
28000 -26.8 -16.2 005 14 7 8.1 4.4 | -26.8 -16.2 015 12 6 8.0 4.4
27000 -24.5 -12.1 005 14 7 7.9 4.3 | -24.4 -11.9 015 10 5 8.0 4.4
26000 -22.1 -7.8 360 13 7 7.9 4.3 | -22.0 -7.6 010 9 5 8.0 4.4
25000 -19.2 -2.6 355 13 6 6.9 3.8 | -19.0 -2.2 360 8 4 6.8 3.7
24000 -17.2 1.0 340 12 6 6.5 3.6 | -17.1 1.2 335 8 4 6.4 3.5
23000 -15.3 4.5 330 12 6 6.5 3.6 | -15.2 4.6 315 9 5 6.4 3.5
22000 -13.3 8.1 315 12 6 7.5 4.1 | -13.3 8.1 300 11 6 7.4 4.0
21000 -11.0 12.2 310 13 7 7.6 4.2 | -11.1 12.0 295 12 6 7.5 4.1
20000 -8.8 16.2 305 13 7 7.7 4.2 | -8.8 16.2 290 13 7 7.6 4.2
19500 -7.7 18.1 305 14 7 7.7 4.2 | -7.7 18.1 290 13 7 7.6 4.2
19000 -6.5 20.3 300 13 7 7.7 4.2 | -6.6 20.1 285 13 7 7.7 4.2
18500 -5.4 22.3 295 13 7 7.7 4.2 | -5.4 22.3 285 13 7 7.8 4.3
18000 -4.3 24.3 290 12 6 6.9 3.8 | -4.3 24.3 280 13 6 7.5 4.1
17500 -3.2 26.2 285 12 6 6.9 3.8 | -3.2 26.2 280 12 6 7.4 4.1
17000 -2.2 28.0 280 12 6 6.8 3.7 | -2.0 28.4 275 12 6 7.3 4.0
16500 -1.2 29.8 275 12 6 6.7 3.7 | -1.0 30.2 275 12 6 7.2 3.9
16000 -0.2 31.6 270 12 6 6.7 3.7 | 0.1 32.2 270 12 6 7.2 3.9
15500 0.8 33.4 270 13 7 7.0 3.9 | 1.2 34.2 270 12 6 7.2 3.9
15000 1.9 35.4 265 13 7 7.0 3.8 | 2.3 36.1 270 12 6 7.2 3.9
14500 2.9 37.2 265 13 7 7.2 4.0 | 3.3 37.9 270 12 6 7.4 4.1
14000 4.0 39.2 260 14 7 7.2 4.0 | 4.5 40.1 270 12 6 7.5 4.1
13500 5.1 41.2 260 14 7 7.5 4.1 | 5.6 42.1 265 12 6 7.7 4.2
13000 6.3 43.3 260 14 7 7.7 4.2 | 6.7 44.1 270 11 6 7.8 4.3
12500 7.4 45.3 260 14 7 7.8 4.3 | 7.9 46.2 270 11 6 8.0 4.4
12000 8.6 47.5 260 13 7 8.0 4.4 | 9.1 48.4 270 11 5 8.3 4.5
11500 9.8 49.6 260 13 7 8.1 4.4 | 10.4 50.7 270 10 5 8.3 4.6
11000 11.0 51.8 260 13 7 8.1 4.4 | 11.6 52.9 270 10 5 8.4 4.6
10500 12.2 54.0 260 12 6 7.4 4.1 | 12.9 55.2 270 10 5 7.3 4.0
10250 12.8 55.0 260 13 7 8.0 4.4 | 13.4 56.1 270 11 5 7.6 4.2
10000 13.4 56.1 265 12 6 9.2 5.0 | 14.1 57.4 270 10 5 9.3 5.1
9750 14.1 57.4 265 12 6 8.9 4.9 | 14.7 58.5 270 10 5 8.8 4.8
9500 14.8 58.6 265 11 6 8.8 4.8 | 15.4 59.7 270 10 5 9.2 5.0
9250 15.4 59.7 270 11 6 8.4 4.6 | 16.1 61.0 270 10 5 9.4 5.2
9000 16.0 60.8 270 11 6 8.2 4.5 | 16.8 62.2 270 11 5 8.6 4.7
8750 17.2 63.0 270 10 5 7.6 4.2 | 18.0 64.4 270 10 5 7.8 4.3
8500 17.7 63.9 275 10 5 6.0 3.3 | 18.5 65.3 270 10 5 6.5 3.6
8250 18.2 64.8 280 10 5 8.4 4.6 | 19.1 66.4 275 10 5 8.0 4.4
8000 19.0 66.2 280 9 5 11.2 6.1 | 19.7 67.5 275 10 5 10.0 5.5
7750 19.7 67.5 280 8 4 9.2 5.1 | 20.4 68.7 275 9 5 8.2 4.5
7500 20.3 68.5 285 9 4 7.4 4.0 | 21.0 69.8 275 9 5 6.5 3.6
7250 20.9 69.6 285 9 4 9.4 5.2 | 21.5 70.7 280 9 5 7.7 4.2
7000 21.8 71.2 285 8 4 12.4 6.8 | 22.1 71.8 280 8 4 10.2 5.6
6750 22.7 72.9 285 8 4 11.0 6.1 | 22.9 73.2 275 8 4 10.4 5.7
6500 23.4 74.1 290 8 4 9.5 5.2 | 23.6 74.5 280 8 4 9.5 5.2
6250 24.1 75.4 290 8 4 9.6 5.3 | 24.4 75.9 280 8 4 9.3 5.1
6000 25.0 77.0 285 7 4 15.3 8.4 | 25.0 77.0 280 7 4 8.1 4.4
5750 26.5 79.7 295 7 4 25.8 14.2 | 25.6 78.1 285 6 3 8.0 4.4
5500 28.1 82.6 300 7 4 6.7 3.7 | 26.2 79.2 290 6 3 10.3 5.7
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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