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Soaring Guidance
Issued by NWS Grand Junction, CO
Issued by NWS Grand Junction, CO
000
UXUS97 KGJT 201307
SRGGJT
Soaring Forecast
National Weather Service Grand Junction, Colorado
707 AM MDT Saturday, April 20, 2024
This forecast is for Saturday, April 20, 2024:
If the trigger temperature of 62.5 F/17.0 C is reached...then
Thermal Soaring Index....................... Excellent
Maximum rate of lift........................ 1209 ft/min (6.1 m/s)
Maximum height of thermals.................. 18231 ft MSL (13392 ft AGL)
Forecast maximum temperature................... 74.0 F/23.8 C
Time of trigger temperature.................... 1000 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................. 14541 ft MSL (9702 ft AGL)
Thermal soaring outlook for Sunday 04/21....... Excellent
Wave Soaring Index............................. Not available
Remarks...
Sunrise/Sunset.................... 06:29:00 / 19:56:45 MDT
Total possible sunshine........... 13 hr 27 min 45 sec (807 min 45 sec)
Altitude of sun at 13:12:53 MDT... 62.62 degrees
Upper air data from rawinsonde observation taken on 04/20/2024 at 0600 MDT
Freezing level.................. 11112 ft MSL (6273 ft AGL)
Convective condensation level... 13541 ft MSL (8702 ft AGL)
Lifted condensation level....... 15115 ft MSL (10276 ft AGL)
Lifted index.................... -2.0
K index......................... +20.4
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 -55.7 -68.3 275 37 19 3.0 1.6 109.0 228.3 48.8 M M
45000 -54.5 -66.1 270 45 23 -4.3 -2.4 85.0 185.0 37.7 M M
40000 -59.6 -75.3 270 33 17 4.9 2.7 53.7 128.7 19.8 M M
38000 -57.5 -71.5 295 42 21 3.5 1.9 48.1 118.5 16.6 M M
36000 -55.4 -67.7 290 41 21 2.7 1.5 42.5 108.5 13.2 M M
34000 -54.1 -65.4 285 41 21 7.8 4.3 36.1 97.0 9.0 M M
32000 -49.0 -56.2 280 43 22 7.8 4.3 33.9 93.0 7.7 M M
30000 -44.2 -47.6 265 43 22 7.4 4.1 32.5 90.5 6.9 M M
29000 -41.9 -43.4 260 42 22 8.9 4.9 31.8 89.2 6.4 M M
28000 -39.2 -38.6 255 38 20 7.8 4.3 31.4 88.5 6.2 M M
27000 -36.9 -34.4 260 37 19 8.2 4.5 30.7 87.2 5.7 M M
26000 -34.4 -29.9 260 37 19 8.6 4.7 30.1 86.3 5.3 M M
25000 -31.9 -25.4 250 37 19 8.6 4.7 29.7 85.5 5.0 M M
24000 -29.4 -20.9 250 37 19 8.7 4.8 29.2 84.5 4.6 M M
23000 -26.9 -16.4 250 34 18 8.1 4.4 28.7 83.6 4.3 M M
22000 -24.7 -12.5 255 34 18 7.2 3.9 27.8 82.0 3.5 M M
21000 -22.6 -8.7 260 35 18 7.5 4.1 26.9 80.3 2.8 M M
20000 -20.5 -4.9 270 34 17 6.6 3.6 25.8 78.5 1.9 M M
19500 -19.5 -3.1 270 34 17 7.2 4.0 25.3 77.6 1.5 M M
19000 -18.4 -1.1 270 34 18 7.5 4.1 24.9 76.8 1.1 M M
18500 -17.6 0.3 270 33 17 4.6 2.5 24.2 75.6 0.6 M M
18000 -16.8 1.8 275 31 16 4.6 2.5 23.4 74.1 -0.2 1201 6.1
17500 -15.9 3.4 275 27 14 7.7 4.2 22.8 73.0 -0.7 1158 5.9
17000 -14.3 6.3 275 25 13 7.4 4.0 22.2 71.9 -1.3 1087 5.5
16500 -13.2 8.2 285 23 12 7.6 4.2 21.8 71.2 -1.7 1040 5.3
16000 -12.0 10.4 290 26 13 7.7 4.2 21.4 70.6 -2.0 990 5.0
15500 -11.0 12.2 295 26 13 6.3 3.4 21.0 69.7 -2.4 945 4.8
15000 -9.9 14.2 295 25 13 8.4 4.6 20.6 69.0 -2.8 898 4.6
14500 -8.7 16.3 295 24 13 8.3 4.6 20.3 68.6 -3.1 845 4.3
14000 -7.4 18.7 300 20 10 8.3 4.6 20.1 68.2 -3.3 793 4.0
13500 -6.2 20.8 295 18 9 8.0 4.4 19.8 67.7 -3.6 742 3.8
13000 -5.1 22.8 280 15 8 9.0 5.0 19.6 67.3 -3.9 693 3.5
12500 -3.7 25.3 285 15 8 9.1 5.0 19.5 67.2 -4.0 637 3.2
12000 -2.4 27.7 275 13 7 9.1 5.0 19.4 67.0 -4.1 582 3.0
11500 -1.0 30.2 280 13 7 9.1 5.0 19.3 66.8 -4.2 526 2.7
11000 0.4 32.7 280 15 8 9.5 5.2 19.2 66.6 -4.4 471 2.4
10500 1.5 34.7 270 13 6 5.0 2.8 18.9 65.9 -4.7 422 2.1
10250 1.8 35.2 260 11 6 5.5 3.0 18.5 65.3 -5.1 404 2.1
10000 2.3 36.1 250 11 6 7.0 3.9 18.2 64.8 -5.4 383 1.9
9750 2.8 37.0 255 10 5 8.0 4.4 18.0 64.5 -5.6 360 1.8
9500 3.4 38.1 260 8 4 8.2 4.5 17.9 64.3 -5.8 335 1.7
9250 4.0 39.2 270 7 4 8.1 4.5 17.8 64.1 -5.9 309 1.6
9000 4.6 40.3 260 7 4 8.2 4.5 17.7 63.9 -6.0 284 1.4
8750 5.2 41.4 255 5 3 8.2 4.5 17.6 63.7 -6.2 258 1.3
8500 5.8 42.4 250 4 2 8.2 4.5 17.5 63.4 -6.3 233 1.2
8250 6.4 43.5 230 2 1 8.2 4.5 17.4 63.2 -6.4 207 1.1
8000 7.0 44.6 215 6 3 8.2 4.5 17.2 63.0 -6.6 182 0.9
7750 7.6 45.7 215 6 3 8.2 4.5 17.1 62.8 -6.7 156 0.8
7500 8.2 46.8 210 5 3 8.2 4.5 17.0 62.6 -6.8 131 0.7
7250 8.8 47.8 205 4 2 8.2 4.5 16.9 62.4 -7.0 105 0.5
7000 9.5 49.1 175 4 2 8.2 4.5 16.8 62.2 -7.1 80 0.4
6750 10.1 50.2 155 5 2 8.2 4.5 16.6 61.9 -7.3 54 0.3
6500 10.7 51.3 120 5 2 8.2 4.5 16.5 61.7 -7.4 29 0.1
6250 11.3 52.3 095 6 3 8.2 4.5 16.4 61.5 -7.6 4 0.0
6000 11.9 53.4 065 5 2 8.2 4.5 16.2 61.2 -7.7 M M
5750 12.5 54.5 060 4 2 8.2 4.5 16.1 61.0 -7.9 M M
5500 13.0 55.4 080 4 2 7.1 3.9 16.0 60.7 -8.1 M M
5250 13.4 56.1 100 4 2 2.4 1.3 15.6 60.1 -8.5 M M
5000 13.0 55.4 110 5 3 -14.0 -7.7 14.6 58.2 -9.6 M M
* * * * * * Numerical weather prediction model forecast data valid * * * * * *
04/20/2024 at 0900 MDT | 04/20/2024 at 1200 MDT
|
CAPE... +1.9 LI... +0.7 | CAPE... +19.0 LI... +0.5
CINH... -5.9 K Index... +21.5 | CINH... -8.6 K Index... +19.0
|
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 -56.4 -69.5 275 39 20 0.9 0.5 | -56.4 -69.5 275 39 20 0.6 0.3
45000 -55.1 -67.2 275 40 21 -2.1 -1.1 | -55.5 -67.9 275 40 21 -2.5 -1.4
40000 -59.7 -75.5 290 41 21 -3.1 -1.7 | -60.4 -76.7 290 44 23 -3.3 -1.8
38000 -59.1 -74.4 295 42 21 4.9 2.7 | -59.5 -75.1 290 46 24 5.4 3.0
36000 -56.1 -69.0 305 41 21 4.9 2.7 | -56.3 -69.3 295 47 24 5.4 3.0
34000 -52.3 -62.1 310 40 21 7.9 4.3 | -52.2 -62.0 295 47 24 7.8 4.3
32000 -47.6 -53.7 310 37 19 7.9 4.3 | -47.5 -53.5 295 46 24 7.8 4.3
30000 -42.9 -45.2 305 34 18 7.5 4.1 | -42.7 -44.9 295 44 23 8.4 4.6
29000 -40.7 -41.3 300 33 17 7.5 4.1 | -40.2 -40.4 295 43 22 8.4 4.6
28000 -38.4 -37.1 295 33 17 7.5 4.1 | -37.7 -35.9 290 41 21 8.4 4.6
27000 -36.2 -33.2 290 32 17 6.8 3.7 | -35.2 -31.4 290 40 20 7.1 3.9
26000 -34.3 -29.7 285 33 17 6.5 3.6 | -33.2 -27.8 290 39 20 6.9 3.8
25000 -32.3 -26.1 280 33 17 6.5 3.6 | -31.1 -24.0 285 38 20 6.9 3.8
24000 -30.4 -22.7 275 34 18 7.0 3.9 | -29.1 -20.4 285 38 19 6.4 3.5
23000 -28.1 -18.6 275 34 18 7.7 4.3 | -27.3 -17.1 285 37 19 5.9 3.2
22000 -25.8 -14.4 275 35 18 7.8 4.3 | -25.1 -13.2 280 35 18 6.0 3.3
21000 -23.0 -9.4 270 34 18 7.1 3.9 | -23.2 -9.8 280 35 18 7.5 4.1
20000 -20.9 -5.6 270 33 17 7.1 3.9 | -21.0 -5.8 275 34 18 7.5 4.1
19500 -19.9 -3.8 270 32 17 7.1 3.9 | -19.9 -3.8 275 34 17 7.5 4.1
19000 -18.8 -1.8 270 31 16 7.2 3.9 | -18.8 -1.8 275 34 17 7.6 4.1
18500 -17.8 -0.0 270 31 16 6.9 3.8 | -17.7 0.1 275 33 17 7.7 4.2
18000 -16.8 1.8 270 29 15 6.9 3.8 | -16.5 2.3 275 32 17 7.7 4.2
17500 -15.8 3.6 270 28 15 7.1 3.9 | -15.4 4.3 270 32 16 7.5 4.1
17000 -14.8 5.4 270 27 14 7.1 3.9 | -14.3 6.3 270 30 16 7.4 4.0
16500 -13.7 7.3 275 26 13 7.2 3.9 | -13.3 8.1 270 29 15 7.3 4.0
16000 -12.7 9.1 275 25 13 7.3 4.0 | -12.2 10.0 270 28 14 6.8 3.8
15500 -11.6 11.1 275 24 12 7.2 4.0 | -11.2 11.8 270 26 14 6.8 3.8
15000 -10.5 13.1 275 23 12 7.5 4.1 | -10.2 13.6 270 25 13 7.2 4.0
14500 -9.4 15.1 280 21 11 7.5 4.1 | -9.2 15.4 270 23 12 7.1 3.9
14000 -8.2 17.2 280 20 10 8.1 4.4 | -8.1 17.4 275 22 11 7.9 4.3
13500 -7.0 19.4 285 19 10 8.2 4.5 | -6.9 19.6 275 20 10 8.0 4.4
13000 -5.8 21.6 285 18 9 8.4 4.6 | -5.7 21.7 275 19 10 8.3 4.6
12500 -4.5 23.9 290 17 9 8.5 4.6 | -4.4 24.1 275 18 9 8.5 4.6
12000 -3.3 26.1 290 16 8 8.7 4.8 | -3.2 26.2 280 17 9 8.8 4.8
11500 -1.9 28.6 290 15 8 8.8 4.8 | -1.8 28.8 280 16 8 9.0 4.9
11000 -0.7 30.7 290 14 7 8.1 4.5 | -0.5 31.1 285 15 8 8.6 4.7
10500 0.5 32.9 290 13 7 7.3 4.0 | 0.8 33.4 285 14 7 7.9 4.3
10250 1.1 34.0 285 12 6 9.7 5.3 | 1.4 34.5 285 14 7 10.3 5.7
10000 1.8 35.2 285 11 6 9.6 5.3 | 2.3 36.1 290 13 7 10.8 5.9
9750 2.4 36.3 280 10 5 7.1 3.9 | 3.0 37.4 290 13 6 8.7 4.8
9500 2.9 37.2 280 9 5 7.7 4.2 | 3.6 38.5 290 12 6 9.5 5.2
9250 3.5 38.3 275 8 4 7.7 4.2 | 4.3 39.7 290 12 6 8.4 4.6
9000 4.1 39.4 275 8 4 7.3 4.0 | 4.9 40.8 290 11 6 8.5 4.7
8750 4.6 40.3 275 7 4 6.6 3.6 | 5.6 42.1 290 11 6 9.4 5.1
8500 5.0 41.0 270 6 3 6.8 3.7 | 6.3 43.3 290 10 5 9.7 5.3
8250 5.5 41.9 265 5 3 6.2 3.4 | 7.5 45.5 295 9 5 7.2 3.9
8000 6.4 43.5 260 4 2 6.6 3.6 | 8.1 46.6 295 9 5 9.9 5.5
7750 6.9 44.4 250 3 2 6.9 3.8 | 8.9 48.0 295 8 4 10.7 5.9
7500 7.3 45.1 235 3 1 5.5 3.0 | 9.6 49.3 295 8 4 8.9 4.9
7250 7.7 45.9 215 3 1 4.3 2.4 | 10.2 50.4 295 8 4 7.9 4.3
7000 8.0 46.4 200 3 2 7.7 4.2 | 10.9 51.6 295 8 4 11.2 6.1
6750 8.7 47.7 180 3 1 9.2 5.0 | 11.8 53.2 295 7 4 12.2 6.7
6500 9.3 48.7 175 3 1 7.6 4.1 | 12.6 54.7 295 7 4 10.5 5.8
6250 9.8 49.6 175 3 1 7.1 3.9 | 13.4 56.1 300 7 4 10.2 5.6
6000 10.4 50.7 175 3 1 9.2 5.0 | 14.2 57.6 300 7 4 11.2 6.1
5750 11.3 52.3 165 2 1 17.0 9.3 | 15.3 59.5 295 6 3 20.5 11.3
5500 12.8 55.0 170 2 1 21.4 11.7 | 17.7 63.9 300 7 3 48.5 26.6
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
04/20/2024 at 1500 MDT | 04/20/2024 at 1800 MDT
|
CAPE... +21.9 LI... +0.1 | CAPE... +24.0 LI... -0.5
CINH... -4.7 K Index... +20.4 | CINH... -6.1 K Index... +23.1
|
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 -56.7 -70.1 280 40 21 0.9 0.5 | -57.3 -71.1 290 42 22 0.5 0.3
45000 -55.5 -67.9 280 42 22 -2.7 -1.5 | -56.7 -70.1 285 48 25 -2.3 -1.3
40000 -60.4 -76.7 295 48 25 -3.3 -1.8 | -60.6 -77.1 295 50 26 -2.7 -1.5
38000 -59.5 -75.1 295 50 26 5.3 2.9 | -59.5 -75.1 295 50 26 5.2 2.8
36000 -56.0 -68.8 295 53 27 5.3 2.9 | -56.0 -68.8 290 51 26 5.2 2.8
34000 -52.1 -61.8 295 53 28 8.4 4.6 | -52.2 -62.0 290 51 26 8.6 4.7
32000 -47.1 -52.8 295 51 26 8.4 4.6 | -47.0 -52.6 295 48 25 8.6 4.7
30000 -42.2 -44.0 295 49 25 7.9 4.4 | -42.0 -43.6 295 46 24 8.2 4.5
29000 -39.8 -39.6 295 47 24 7.9 4.3 | -39.5 -39.1 295 45 23 8.2 4.5
28000 -37.4 -35.3 295 45 23 7.9 4.4 | -37.1 -34.8 300 44 23 8.2 4.5
27000 -35.1 -31.2 290 43 22 6.7 3.7 | -34.8 -30.6 300 43 22 6.5 3.6
26000 -33.1 -27.6 290 41 21 6.7 3.7 | -32.8 -27.0 300 42 22 6.5 3.6
25000 -31.1 -24.0 295 39 20 6.7 3.7 | -30.9 -23.6 300 41 21 6.5 3.6
24000 -29.1 -20.4 295 37 19 6.7 3.7 | -28.9 -20.0 300 40 20 6.7 3.7
23000 -27.1 -16.8 290 35 18 6.8 3.7 | -26.9 -16.4 300 38 19 6.8 3.8
22000 -24.6 -12.3 290 33 17 6.8 3.7 | -24.3 -11.7 300 36 18 6.8 3.8
21000 -22.6 -8.7 285 31 16 6.7 3.7 | -22.3 -8.1 295 34 17 6.7 3.7
20000 -20.6 -5.1 285 30 15 6.7 3.7 | -20.3 -4.5 295 31 16 6.7 3.7
19500 -19.6 -3.3 280 30 15 6.8 3.7 | -19.3 -2.7 295 30 15 6.8 3.7
19000 -18.6 -1.5 280 29 15 6.9 3.8 | -18.4 -1.1 295 29 15 6.9 3.8
18500 -17.6 0.3 280 28 14 7.7 4.2 | -17.3 0.9 290 27 14 7.3 4.0
18000 -16.4 2.5 280 27 14 7.7 4.2 | -16.3 2.7 290 26 14 7.2 4.0
17500 -15.3 4.5 280 26 13 7.7 4.2 | -15.2 4.6 285 25 13 8.5 4.6
17000 -14.2 6.4 280 25 13 7.7 4.2 | -13.9 7.0 285 24 12 8.7 4.8
16500 -13.1 8.4 280 24 12 7.8 4.3 | -12.6 9.3 285 22 11 8.5 4.7
16000 -11.9 10.6 280 23 12 8.0 4.4 | -11.4 11.5 285 20 11 8.3 4.5
15500 -10.7 12.7 280 22 11 8.1 4.4 | -10.2 13.6 285 19 10 8.3 4.5
15000 -9.5 14.9 280 20 10 8.5 4.7 | -9.0 15.8 285 17 9 8.5 4.6
14500 -8.3 17.1 280 19 10 8.5 4.7 | -7.7 18.1 290 16 8 8.4 4.6
14000 -7.0 19.4 280 18 9 8.6 4.7 | -6.5 20.3 290 15 8 8.9 4.9
13500 -5.7 21.7 280 18 9 8.6 4.7 | -5.1 22.8 290 15 8 8.8 4.9
13000 -4.4 24.1 280 17 9 9.0 4.9 | -3.8 25.2 290 14 7 9.2 5.0
12500 -3.1 26.4 280 16 8 9.0 4.9 | -2.4 27.7 295 14 7 9.2 5.1
12000 -1.7 28.9 280 16 8 9.0 5.0 | -1.0 30.2 295 14 7 9.4 5.1
11500 -0.4 31.3 285 15 8 9.1 5.0 | 0.4 32.7 295 14 7 9.4 5.2
11000 0.9 33.6 285 15 8 8.5 4.6 | 1.7 35.1 300 13 7 8.7 4.8
10500 2.2 36.0 285 14 7 7.8 4.3 | 3.0 37.4 300 13 7 8.0 4.4
10250 2.8 37.0 285 14 7 10.2 5.6 | 3.7 38.7 300 13 7 10.8 5.9
10000 3.7 38.7 285 14 7 10.9 6.0 | 4.6 40.3 305 13 7 11.3 6.2
9750 4.4 39.9 290 14 7 9.0 5.0 | 5.3 41.5 305 13 7 8.7 4.8
9500 5.1 41.2 290 14 7 9.7 5.3 | 6.0 42.8 305 13 7 9.4 5.2
9250 5.8 42.4 290 14 7 9.0 4.9 | 6.7 44.1 305 13 6 9.1 5.0
9000 6.4 43.5 290 13 7 9.3 5.1 | 7.3 45.1 305 12 6 9.2 5.1
8750 7.2 45.0 290 13 7 9.9 5.4 | 8.0 46.4 310 12 6 9.4 5.2
8500 7.9 46.2 290 13 7 10.0 5.5 | 8.7 47.7 310 12 6 9.6 5.3
8250 8.6 47.5 290 13 7 9.0 4.9 | 9.4 48.9 310 12 6 8.7 4.8
8000 10.0 50.0 295 13 7 10.9 6.0 | 10.8 51.4 310 12 6 10.1 5.5
7750 10.8 51.4 295 13 7 11.1 6.1 | 11.5 52.7 310 12 6 10.3 5.7
7500 11.6 52.9 295 13 7 8.8 4.8 | 12.3 54.1 310 11 6 8.9 4.9
7250 12.2 54.0 295 13 7 7.7 4.2 | 12.9 55.2 315 11 6 8.2 4.5
7000 12.9 55.2 295 13 6 11.4 6.3 | 13.6 56.5 315 11 6 10.6 5.8
6750 13.8 56.8 295 12 6 12.4 6.8 | 14.4 57.9 310 11 6 11.3 6.2
6500 14.7 58.5 295 12 6 10.5 5.8 | 15.2 59.4 315 11 6 10.0 5.5
6250 15.4 59.7 295 12 6 10.2 5.6 | 15.9 60.6 315 11 6 9.9 5.5
6000 16.2 61.2 300 12 6 11.4 6.2 | 16.7 62.1 315 11 6 9.6 5.3
5750 17.3 63.1 295 11 6 21.3 11.7 | 17.5 63.5 315 10 5 13.4 7.4
5500 19.8 67.6 300 10 5 49.4 27.1 | 19.1 66.4 320 9 5 35.8 19.6
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.
042613
- National Weather Service
- La Crosse, WI Weather Forecast Office
- N2788 County Road FA
- LaCrosse, WI 54601
- 608-784-7294
- Page Author: ARX Webmaster
- Web Master's E-mail: w-arx.webmaster@noaa.gov
- Page last modified: Sep 19th, 2023 19:10 UTC