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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 241220
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
0620 MDT Tuesday, April 24, 2018
This forecast is for Tuesday, April 24, 2018:
If the trigger temperature of 63.3 F/17.4 C is reached...then
Thermal Soaring Index....................... Good
Maximum rate of lift........................ 494 ft/min (2.5 m/s)
Maximum height of thermals.................. 11516 ft MSL (6677 ft AGL)
Forecast maximum temperature................... 69.0 F/21.0 C
Time of trigger temperature.................... 1145 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................. 8891 ft MSL (4052 ft AGL)
Thermal soaring outlook for Wednesday 04/25.... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:24:47 / 19:59:28 MDT
Total possible sunshine........... 13 hr 34 min 41 sec (814 min 41 sec)
Altitude of sun at 13:12:17 MDT... 63.92 degrees
Upper air data from rawinsonde observation taken on 04/24/2018 at 0600 MDT
Freezing level.................. 11681 ft MSL (6842 ft AGL)
Convective condensation level... 14965 ft MSL (10126 ft AGL)
Lifted condensation level....... 14523 ft MSL (9683 ft AGL)
Lifted index.................... +0.6
K index......................... +19.3
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 -60.3 -76.5 280 39 20 4.6 2.5 99.7 211.5 45.2 M M
45000 -59.1 -74.4 285 40 20 0.7 0.4 77.0 170.7 34.5 M M
40000 -61.7 -79.1 280 61 31 6.9 3.8 49.9 121.7 19.2 M M
38000 -57.5 -71.5 285 63 32 6.6 3.6 47.1 116.8 17.9 M M
36000 -53.5 -64.3 285 67 35 6.6 3.6 44.3 111.8 16.5 M M
34000 -49.1 -56.4 285 71 37 5.8 3.2 41.5 106.7 14.9 M M
32000 -45.0 -49.0 285 70 36 8.2 4.5 39.1 102.3 13.5 M M
30000 -40.0 -40.0 285 65 33 8.4 4.6 38.0 100.3 13.1 M M
29000 -37.5 -35.5 280 62 32 7.4 4.1 37.4 99.4 12.8 M M
28000 -35.6 -32.1 280 59 30 6.4 3.5 36.0 96.9 11.9 M M
27000 -33.7 -28.7 275 56 29 6.4 3.5 34.8 94.7 11.1 M M
26000 -32.0 -25.6 270 53 27 5.4 2.9 33.2 91.8 10.0 M M
25000 -30.8 -23.4 265 51 26 2.1 1.2 31.0 87.8 8.3 M M
24000 -29.6 -21.3 260 47 24 8.5 4.7 29.0 84.2 6.7 M M
23000 -26.9 -16.4 260 45 23 9.3 5.1 28.7 83.7 6.5 M M
22000 -24.6 -12.3 260 42 22 7.3 4.0 27.9 82.2 5.9 M M
21000 -22.5 -8.5 260 40 21 7.3 4.0 27.1 80.7 5.3 M M
20000 -20.1 -4.2 265 42 21 6.7 3.7 26.4 79.6 4.8 M M
19500 -19.2 -2.6 265 43 22 7.1 3.9 25.8 78.4 4.3 M M
19000 -17.4 0.7 270 44 23 7.6 4.2 25.3 77.6 3.9 M M
18500 -16.4 2.5 270 45 23 7.8 4.3 24.8 76.7 3.4 M M
18000 -15.1 4.8 270 44 23 8.9 4.9 24.7 76.5 3.3 M M
17500 -13.8 7.2 270 42 22 8.8 4.8 24.5 76.1 3.1 M M
17000 -12.9 8.8 270 40 20 4.1 2.3 24.0 75.1 2.6 M M
16500 -12.2 10.0 275 37 19 7.1 3.9 23.1 73.6 1.9 M M
16000 -10.8 12.6 275 35 18 8.8 4.8 22.9 73.3 1.8 M M
15500 -9.6 14.7 275 34 17 7.8 4.3 22.7 72.9 1.5 M M
15000 -8.4 16.9 275 32 17 7.8 4.3 22.4 72.3 1.3 M M
14500 -7.3 18.9 280 31 16 5.5 3.0 22.1 71.7 1.0 M M
14000 -6.2 20.8 280 30 15 9.6 5.3 21.6 70.9 0.6 M M
13500 -4.8 23.4 280 26 13 9.0 4.9 21.5 70.6 0.5 M M
13000 -3.5 25.7 285 23 12 8.9 4.9 21.3 70.4 0.4 M M
12500 -2.2 28.0 280 21 11 8.9 4.9 21.2 70.2 0.2 M M
12000 -0.8 30.6 275 19 10 8.9 4.9 21.1 69.9 0.1 M M
11500 0.5 32.9 270 14 7 8.7 4.8 20.9 69.7 -0.0 491 2.5
11000 1.3 34.3 265 10 5 2.9 1.6 20.2 68.3 -0.7 454 2.3
10500 1.7 35.1 255 6 3 4.6 2.5 19.2 66.5 -1.8 426 2.2
10250 2.1 35.8 235 4 2 7.5 4.1 18.9 66.0 -2.1 406 2.1
10000 2.7 36.9 225 4 2 8.0 4.4 18.8 65.8 -2.2 381 1.9
9750 3.3 37.9 205 5 3 7.8 4.3 18.6 65.5 -2.4 356 1.8
9500 3.9 39.0 190 6 3 7.8 4.3 18.4 65.2 -2.6 332 1.7
9250 4.4 39.9 180 8 4 7.9 4.3 18.3 64.9 -2.7 307 1.6
9000 5.0 41.0 175 10 5 7.6 4.2 18.2 64.7 -2.9 282 1.4
8750 5.5 41.9 170 12 6 6.9 3.3 17.9 64.3 -3.1 260 1.3
8500 5.9 42.6 165 14 7 5.0 2.7 17.6 63.6 -3.5 241 1.2
8250 6.3 43.3 160 16 8 5.4 3.0 17.2 63.0 -3.9 223 1.1
8000 6.6 43.9 155 18 9 4.7 2.6 16.9 62.4 -4.2 205 1.0
7750 7.0 44.6 150 17 9 7.2 4.0 16.5 61.7 -4.6 186 0.9
7500 7.7 45.9 145 16 8 9.8 5.4 16.5 61.7 -4.6 158 0.8
7250 8.4 47.1 140 16 8 9.2 5.0 16.4 61.6 -4.7 129 0.7
7000 9.1 48.4 135 15 8 9.3 5.1 16.4 61.6 -4.7 101 0.5
6750 9.8 49.6 135 13 7 9.3 5.1 16.4 61.5 -4.7 72 0.4
6500 10.5 50.9 130 11 6 9.3 5.1 16.3 61.4 -4.8 44 0.2
6250 11.2 52.2 125 9 5 9.4 5.2 16.3 61.3 -4.8 15 0.1
6000 11.9 53.4 120 8 4 8.9 4.9 16.3 61.3 -4.9 M M
5750 12.5 54.5 115 6 3 5.3 2.9 16.1 61.0 -5.0 M M
5500 12.8 55.0 120 6 3 3.2 1.7 15.6 60.1 -5.5 M M
5250 13.0 55.4 120 5 3 4.0 2.2 15.2 59.3 -6.0 M M
5000 13.3 55.9 125 4 2 2.8 1.5 14.7 58.5 -6.5 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/24/2018 at 0900 MDT | 04/24/2018 at 1200 MDT
|
K index... +19.2 LI... -0.3 | K index... +18.0 LI... +1.4
CAPE... +4.5 CIN... -40.9 | CAPE... 0.0 CIN... 0.0
|
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 -59.7 -75.5 295 33 17 1.2 0.6 | -59.7 -75.5 295 31 16 1.0 0.6
45000 -58.2 -72.8 290 46 24 -1.7 -1.0 | -58.3 -72.9 295 46 24 -0.7 -0.4
40000 -60.4 -76.7 285 57 29 -1.4 -0.8 | -59.1 -74.4 280 57 29 -0.5 -0.3
38000 -58.0 -72.4 285 60 31 6.9 3.8 | -56.7 -70.1 280 60 31 5.4 3.0
36000 -53.3 -63.9 285 63 32 6.9 3.8 | -53.4 -64.1 280 62 32 5.4 3.0
34000 -49.0 -56.2 285 65 33 7.7 4.2 | -49.6 -57.3 280 63 33 8.0 4.4
32000 -44.4 -47.9 285 66 34 7.7 4.2 | -44.8 -48.6 280 63 33 7.9 4.4
30000 -39.7 -39.5 285 67 34 8.1 4.4 | -39.9 -39.8 280 64 33 8.3 4.5
29000 -37.3 -35.1 285 66 34 8.1 4.4 | -37.5 -35.5 280 65 33 8.3 4.5
28000 -34.8 -30.6 285 66 34 8.1 4.4 | -35.0 -31.0 280 66 34 8.3 4.5
27000 -32.6 -26.7 285 65 34 6.3 3.5 | -32.6 -26.7 280 66 34 6.7 3.7
26000 -30.6 -23.1 280 63 32 6.5 3.6 | -30.5 -22.9 280 65 33 6.8 3.7
25000 -28.7 -19.7 280 60 31 6.5 3.6 | -28.5 -19.3 280 63 33 6.8 3.7
24000 -26.7 -16.1 275 57 29 5.8 3.2 | -26.5 -15.7 280 62 32 6.2 3.4
23000 -25.1 -13.2 275 54 28 5.6 3.1 | -24.7 -12.5 280 59 31 6.0 3.3
22000 -23.4 -10.1 275 51 26 5.6 3.1 | -22.9 -9.2 275 57 29 6.0 3.3
21000 -21.8 -7.2 270 47 24 4.7 2.6 | -20.7 -5.3 275 53 27 5.4 3.0
20000 -20.1 -4.2 270 43 22 4.8 2.6 | -19.1 -2.4 275 50 26 5.4 3.0
19500 -19.4 -2.9 270 42 22 4.9 2.7 | -18.3 -0.9 275 48 25 5.4 3.0
19000 -18.6 -1.5 270 40 21 5.6 3.1 | -17.5 0.5 275 46 24 5.6 3.1
18500 -17.6 0.3 270 39 20 8.3 4.6 | -16.6 2.1 275 44 23 6.3 3.4
18000 -16.4 2.5 275 38 20 8.3 4.5 | -15.7 3.7 275 42 22 6.3 3.5
17500 -15.2 4.6 275 38 19 8.4 4.6 | -14.9 5.2 275 41 21 5.6 3.1
17000 -13.9 7.0 275 37 19 8.5 4.6 | -14.1 6.6 275 39 20 5.8 3.2
16500 -12.7 9.1 275 37 19 8.7 4.8 | -13.3 8.1 275 38 19 7.0 3.8
16000 -11.4 11.5 275 37 19 8.9 4.9 | -12.1 10.2 275 36 19 8.2 4.5
15500 -10.1 13.8 280 36 19 8.9 4.9 | -10.9 12.4 275 35 18 8.4 4.6
15000 -8.9 16.0 280 34 18 8.6 4.7 | -9.7 14.5 275 32 17 8.8 4.8
14500 -7.6 18.3 280 33 17 8.7 4.8 | -8.4 16.9 270 30 15 8.9 4.9
14000 -6.4 20.5 280 30 16 7.4 4.1 | -7.3 18.9 275 27 14 7.2 3.9
13500 -5.3 22.5 285 28 14 7.7 4.2 | -6.2 20.8 275 24 12 7.4 4.1
13000 -4.3 24.3 285 25 13 5.8 3.2 | -5.1 22.8 275 21 11 6.1 3.4
12500 -3.4 25.9 290 23 12 5.8 3.2 | -4.2 24.4 275 18 9 6.2 3.4
12000 -2.5 27.5 295 19 10 5.3 2.9 | -3.2 26.2 275 15 8 5.8 3.2
11500 -1.7 28.9 295 15 8 5.3 2.9 | -2.4 27.7 270 12 6 5.6 3.1
11000 -0.8 30.6 295 11 6 6.1 3.3 | -1.4 29.5 270 9 5 7.4 4.0
10500 0.0 32.0 285 7 4 6.8 3.7 | -0.4 31.3 280 7 4 8.5 4.7
10250 0.4 32.7 275 6 3 3.5 1.9 | 0.1 32.2 285 6 3 3.2 1.7
10000 0.6 33.1 275 5 2 3.1 1.7 | 0.1 32.2 300 5 3 1.8 1.0
9750 0.9 33.6 280 4 2 6.2 3.4 | 0.5 32.9 320 5 3 6.3 3.4
9500 1.2 34.2 290 3 1 5.9 3.2 | 0.8 33.4 340 5 3 5.3 2.9
9250 1.6 34.9 310 2 1 4.7 2.6 | 1.2 34.2 355 6 3 5.5 3.0
9000 1.8 35.2 330 2 1 3.7 2.0 | 1.6 34.9 355 6 3 6.6 3.6
8750 2.1 35.8 355 1 1 4.9 2.7 | 2.2 36.0 360 7 3 8.6 4.7
8500 2.5 36.5 020 2 1 5.0 2.8 | 2.8 37.0 005 7 4 9.2 5.1
8250 2.8 37.0 035 2 1 4.7 2.6 | 3.5 38.3 005 8 4 9.5 5.2
8000 3.2 37.8 045 2 1 4.6 2.5 | 4.2 39.6 005 8 4 9.8 5.4
7750 3.5 38.3 050 3 1 4.4 2.4 | 5.0 41.0 005 7 4 9.6 5.3
7500 3.9 39.0 060 3 2 5.3 2.9 | 5.7 42.3 005 7 4 10.2 5.6
7250 4.3 39.7 050 4 2 6.6 3.6 | 6.5 43.7 005 7 4 10.7 5.9
7000 4.8 40.6 045 5 2 6.4 3.5 | 7.3 45.1 005 7 4 10.7 5.9
6750 5.3 41.5 040 5 3 6.8 3.7 | 8.1 46.6 005 7 4 10.3 5.6
6500 5.9 42.6 035 6 3 9.2 5.0 | 8.8 47.8 005 7 4 10.2 5.6
6250 6.6 43.9 035 6 3 10.7 5.9 | 9.6 49.3 005 7 4 10.8 5.9
6000 7.4 45.3 035 5 3 9.8 5.4 | 10.4 50.7 005 7 4 10.1 5.5
5750 8.3 46.9 035 5 3 14.3 7.9 | 11.4 52.5 005 7 4 18.3 10.1
5500 9.6 49.3 035 5 3 22.5 12.4 | 13.3 55.9 005 7 4 33.4 18.3
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
04/24/2018 at 1500 MDT | 04/24/2018 at 1800 MDT
|
K index... +7.0 LI... +2.2 | K index... -7.0 LI... +2.6
CAPE... 0.0 CIN... -0.2 | CAPE... 0.0 CIN... 0.0
|
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 -59.6 -75.3 300 30 15 1.2 0.7 | -59.8 -75.6 300 29 15 1.0 0.6
45000 -57.9 -72.2 295 42 22 -0.9 -0.5 | -58.3 -72.9 295 43 22 -0.6 -0.3
40000 -59.0 -74.2 285 62 32 -0.5 -0.3 | -58.9 -74.0 290 64 33 -0.2 -0.1
38000 -56.7 -70.1 285 66 34 5.3 2.9 | -56.6 -69.9 290 69 36 5.5 3.0
36000 -53.6 -64.5 285 70 36 5.3 2.9 | -53.3 -63.9 290 74 38 5.5 3.0
34000 -49.9 -57.8 285 72 37 7.6 4.2 | -49.5 -57.1 285 77 40 7.7 4.2
32000 -45.3 -49.5 280 70 36 7.6 4.2 | -44.9 -48.8 285 77 40 7.7 4.2
30000 -40.5 -40.9 280 69 36 8.4 4.6 | -40.3 -40.5 285 76 39 8.1 4.4
29000 -38.0 -36.4 280 69 36 8.4 4.6 | -37.8 -36.0 285 75 39 8.1 4.4
28000 -35.5 -31.9 280 69 35 8.4 4.6 | -35.4 -31.7 285 74 38 8.1 4.4
27000 -32.5 -26.5 280 68 35 7.3 4.0 | -32.5 -26.5 285 73 37 7.0 3.8
26000 -30.3 -22.5 280 67 35 7.3 4.0 | -30.4 -22.7 285 71 37 7.0 3.8
25000 -28.2 -18.8 280 66 34 7.3 4.0 | -28.3 -18.9 285 70 36 7.0 3.9
24000 -26.1 -15.0 280 64 33 5.6 3.1 | -26.3 -15.3 285 68 35 5.6 3.1
23000 -24.3 -11.7 280 62 32 5.8 3.2 | -24.6 -12.3 285 65 33 5.7 3.2
22000 -22.6 -8.7 275 59 31 5.8 3.2 | -22.9 -9.2 285 61 32 5.7 3.1
21000 -20.9 -5.6 275 56 29 5.8 3.2 | -21.2 -6.2 285 56 29 4.9 2.7
20000 -19.1 -2.4 275 52 27 5.8 3.2 | -19.8 -3.6 290 49 25 4.9 2.7
19500 -18.3 -0.9 275 50 26 5.8 3.2 | -19.0 -2.2 290 46 23 4.9 2.7
19000 -17.4 0.7 275 48 25 5.8 3.2 | -18.3 -0.9 290 42 22 4.7 2.6
18500 -16.6 2.1 275 46 24 5.4 3.0 | -17.4 0.7 290 39 20 6.9 3.8
18000 -15.8 3.6 275 43 22 5.5 3.0 | -16.4 2.5 290 37 19 6.7 3.7
17500 -14.9 5.2 275 41 21 6.0 3.3 | -15.4 4.3 290 34 18 6.3 3.4
17000 -14.0 6.8 275 38 20 6.2 3.4 | -14.5 5.9 290 32 17 6.0 3.3
16500 -13.1 8.4 275 36 18 6.3 3.4 | -13.6 7.5 290 31 16 6.1 3.4
16000 -12.1 10.2 275 34 17 6.5 3.6 | -12.6 9.3 290 29 15 7.0 3.9
15500 -11.2 11.8 275 32 16 6.5 3.6 | -11.6 11.1 290 28 14 7.0 3.9
15000 -10.2 13.6 270 30 15 7.3 4.0 | -10.6 12.9 290 27 14 6.7 3.7
14500 -9.2 15.4 270 29 15 7.4 4.1 | -9.6 14.7 290 26 13 6.7 3.7
14000 -8.1 17.4 270 27 14 8.3 4.5 | -8.6 16.5 290 24 13 7.7 4.2
13500 -6.9 19.6 270 25 13 8.5 4.7 | -7.4 18.7 295 23 12 7.9 4.3
13000 -5.2 22.6 270 22 11 7.2 3.9 | -5.7 21.7 300 19 10 7.2 4.0
12500 -4.1 24.6 275 19 10 7.3 4.0 | -4.7 23.5 305 16 8 7.3 4.0
12000 -3.1 26.4 280 15 8 6.3 3.5 | -3.7 25.3 315 14 7 6.8 3.7
11500 -2.2 28.0 300 11 6 6.4 3.5 | -2.7 27.1 335 12 6 6.9 3.8
11000 -1.2 29.8 320 9 5 6.3 3.5 | -1.6 29.1 350 12 6 8.4 4.6
10500 -0.3 31.5 345 10 5 5.2 2.9 | -0.4 31.3 360 13 6 6.8 3.7
10250 -0.0 32.0 350 10 5 4.5 2.4 | -0.0 32.0 005 13 7 5.1 2.8
10000 0.4 32.7 355 10 5 8.5 4.6 | 0.5 32.9 005 13 7 9.4 5.2
9750 1.1 34.0 355 10 5 10.6 5.8 | 1.3 34.3 005 13 7 12.2 6.7
9500 1.9 35.4 360 10 5 9.7 5.3 | 2.2 36.0 005 13 7 10.5 5.8
9250 2.6 36.7 360 10 5 8.9 4.9 | 2.8 37.0 005 13 7 8.1 4.4
9000 3.2 37.8 360 10 5 9.8 5.4 | 3.4 38.1 005 13 7 9.4 5.2
8750 4.0 39.2 360 10 5 11.2 6.1 | 4.3 39.7 010 13 6 11.5 6.3
8500 4.8 40.6 360 11 5 10.2 5.6 | 5.1 41.2 010 13 6 10.4 5.7
8250 5.6 42.1 360 10 5 9.5 5.2 | 5.8 42.4 010 13 6 9.7 5.3
8000 6.3 43.3 360 10 5 9.9 5.4 | 6.6 43.9 010 13 6 10.1 5.5
7750 7.1 44.8 360 10 5 10.4 5.7 | 7.3 45.1 010 12 6 10.5 5.8
7500 7.8 46.0 360 10 5 10.4 5.7 | 8.1 46.6 010 12 6 10.0 5.5
7250 8.6 47.5 360 10 5 10.6 5.8 | 8.8 47.8 010 12 6 9.7 5.3
7000 9.4 48.9 360 10 5 10.0 5.5 | 9.6 49.3 010 12 6 9.9 5.5
6750 10.1 50.2 360 10 5 10.0 5.5 | 10.3 50.5 010 12 6 10.3 5.7
6500 10.9 51.6 360 10 5 11.0 6.0 | 11.1 52.0 010 12 6 10.4 5.7
6250 11.7 53.1 360 10 5 11.2 6.1 | 11.9 53.4 010 12 6 10.6 5.8
6000 12.6 54.7 360 10 5 10.7 5.9 | 12.7 54.9 010 11 6 9.8 5.4
5750 13.4 56.1 360 9 5 14.2 7.8 | 13.4 56.1 010 11 6 10.4 5.7
5500 14.7 58.5 360 10 5 17.8 9.8 | 14.2 57.6 010 11 6 12.0 6.6
5250 15.9 60.6 360 10 5 15.0 8.2 | 15.1 59.2 010 11 6 10.7 5.9
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.
CIN (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.
042613
- National Weather Service
- Binghamton, NY Weather Forecast Office
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- Johnson City, NY 13790
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- Page last modified: Mar 8th, 2018 20:36 UTC